4757444 Wireless Training Site Survey

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Many people think that there is a science behind installing a Wireless LAN (WLAN). While there is certainly a lot of science behind the technology, performing a site survey may be thought of more as an art. Scientists are traditionally thought of as stringent and unable to operate "outside the box." Artists are bold and creative. As a WLAN site survey engineer, you will have to be knowledgeable on both the wireless equipment you are installing, as well as the wired equipment with which you may be interfacing. You will often have to be creative in the design and implementation of the WLAN equipment. A good site survey engineer will be able to think "outside the box," allowing him to overcome limitations presented by the facility as well as the equipment.

• A site survey will help the customer determine how many access points (APs) will be needed throughout the facility to provide the desired coverage. It will also determine the placement of those APs as well as detail the necessary information for installation. • A site survey will also determine the feasibility of the desired coverage in the face of obstacles such as wired connectivity limitations, radio hazards, and application requirements. This will allow the customer to properly install the WLAN and have consistent, reliable wireless access. • In this class we will provide you with all of the necessary tools and knowledge needed to perform a site survey. While this is certainly the place to start, it must

be combined with experience. The more experienced and knowledgeable the site survey engineer, the better the survey.

• In this class we will educate you on the processes of performing a site survey. We will show the tools and how to configure and use them. We will give you an idea of the many different industries where you may be required to perform site surveys. • You will be given a list of recommended equipment for a site survey kit that should get you through almost any site survey. • We will discuss techniques for performing a site survey. And we will try and make you aware of many of the "gotcha's," pointing out some of the concerns that you may not even think to consider when performing a site

survey. • In short, we will try to share our many years' of experience in the field performing site surveys and installations.

• The Open Systems Interconnection (OSI) reference model provides a useful structure for defining and describing the various processes in open systems networking. The OSI model may be thought of as a blueprint for developers to use when designing protocol implementations. • There are seven layers to the OSI model, each dealing with a portion of the communication processes. Although we will explain the function of each level, our primary concern will be the lower two levels of the model. Cisco's

Aironet APs operate at these levels. An AP is referred to as a "Layer 2 Device". • The seven layers of the OSI model are: Application, Presentation, Session, Transport, Network, Data Link, and Physical

• The Physical layer deals with issues concerning transmitting and receiving data across a network, regardless of the media type used. This layer is specifically concerned with the physical structure of the network (or topology), bit transmission and timing, and specifications for interfacing with the media.

• The Data Link layer is actually divided into two sublayers, the Media Access Control (MAC) layer, and the Logical Link Control (LLC) layer. The primary focus of the Data Link layer is the conversion of bits into packets (or packets into bits). • The MAC sub-layer provides addressing information for network device communication as well as information allowing multiple devices to share the same media. • The LLC sub-layer is responsible for establishing and maintaining links between network devices.

• The MAC layer is particularly important because wireless devices require their own MAC layer. They are not communicating via cables and, therefore, cannot use the MAC layer developed for cabled media. Cisco's Aironet products were first to market with the MAC layer for the high speed products, and first with an 802.11 b compliant MAC layer.

• The Network layer deals with network addresses, addressing and delivering packets, and communication between devices on different logical networks. • The Transport layer interacts with the network layer to provide quality control and some connection services.

• The Session layer is responsible for communication dialogs (simplex, half duplex, full duplex) between two devices. This includes the establishment, management, and termination of the dialogs. • The Presentation layer handles data encryption, data compression, and converting system data to a machine independent common format.

• The Application layer provides services on the network. Some of these are file, print, e-mail, and database services. This layer provides the interface to the network for applications. However, this layer is not the actual application.

• The Institute of Electrical and Electronics Engineers (IEEE) is one of the largest and most influential bodies in the world for setting global standards. The IEEE is made of committees. We will only be concerned with the 802 committee, which develops standards that govern lowerlayer protocols and interactions with transmission medias. • we will specifically be concerned with the 802.11 standards. Many of you may be familiar with the 802.3 standard or the 802.5 standard. Just as these standards define characteristics related to Ethernet or Token-Ring networks, 802.11 defines characteristics of WLANs.

• 802.11 is a standard that ensures interoperability between WLAN equipment from different manufacturers. The standard specifies three different methods for transmission -Infrared (IR), Frequency Hopping Spread Spectrum (FHSS) or Direct Sequence Spread Spectrum (DSSS). Cisco's Aironet 340 series equipment uses DSSS. • Two of the subsets of the 802.11 standard are 802.11 a and 802.11b. 802.11a covers equipment in the 5GHz range, while 802.11 b covers higher speeds (currently up to 11 Mbps) in the 2.4GHz range. Cisco's Aironet 340 series of products adhere to the 802.11 b standard.

• Under the 802.11 standard you should be able to use any 802.11 wireless client with any 802.11 wireless backbone. This is possible because 802.11 covers the transmission between the client and the AP, association processes, and modulation schemes. However the 802.11 standard does not cover communication between APs across the wired backbone, roaming, wireless links over 1 mile, load balancing, wireless repeaters, etc. Further cooperation from the WLAN vendors will be required before many of these features can be implemented into the standard.

• You need to be aware of these standards, as well as the limitations of 802.11 while designing a WLAN. Because the standard does not cover communication between APs across the wired backbone, it is recommended that the WLAN backbone consist of a single manufacturer's product. Cisco's Aironet products offer superior roaming, load balancing, wireless repeaters, throughput and 11 Mbps (among other functionality above and beyond 802.11). This makes the 340 series an ideal choice for the WLAN backbone. • If the customer desires to use a specific client card adapter, or a data collection terminal (some of which are not equipped with Cisco 340 series radios), it is possible to install an all-Cisco WLAN backbone that will communicate with a number of non-Cisco products. • This will allow the customer a robust, reliable WLAN connection while still remaining 802.11 compliant.

• Just as with wired networks, the topology of your WLAN may take many forms. But in reference to a WLAN, the term "topology" does not refer to architectures such as bus or ring. Instead it refers to the BSA (Basic Service Area) which is comprised of "microcells”. • Each AP has an area of coverage referred to as a "microcell”, or "cell." In an installation comprised of a single AP this is a very simple concept. When multiple APs are installed, the cells must overlap so that the wireless connection is never interrupted while roaming from AP-to-AP. • This is the main purpose of a site survey - to place APs and survey the cells to allow for proper overlap. Too much or too little overlap can cause disruption of the wireless connection to the client.

• Sometimes the topology of the WLAN will be dictated by the layout of the wired LAN to which the WLAN will be connected. If wired connectivity is only available along one side of a 100,000 sq. ft. warehouse, for example, the distance limitations of a Cat 5 cable run (328') may not be sufficient to reach the recommended location of the AP. • This is where the site survey engineer will have to be creative. There are many possible solutions - a wireless hop using a repeater talking back to a wired AP, a repeater or a hub to extend the Cat 5 cable run, or installing a fiber link to provide connectivity on the other side of the warehouse. • As a site survey engineer you are responsible for not

only finding the best locations for the APs, but also finding ways to connect the APs to the wired network.

• It is therefore crucial that the engineer have an understanding of wired networks. This understanding should cover wired LAN topologies, standards, and components. • The understanding of components must include functionality of repeaters, hubs, switches, and routers. Attaching an AP to a hub has very different implications than attaching an AP to a switch, for example. • By understanding the components, you will be able to design a WLAN that meets all specifications for the existing wired LAN topology. You must also be aware of

the media being installed and be sure that the WLAN you design will meet all requirements for that media type as well as state and local building codes.

• As wireless technology continues to evolve, data rates and interference immunity are improving. These improvements make wireless a viable technology for use in most applications. As the acceptance of wireless technologies continues to grow, the advantages of a mobile workforce and a flexible network become more and more clear to network managers.

• As a site survey engineer you need to be aware of specific issues that surround many of the various industries you may come into contact with. • Often IT mangers, upper management, or board members may want to discuss the implementation of wireless equipment in their facility. • All site survey engineers expect that these issues have been worked through with a salesman or SE prior to his arrival. But this is not always the case. • You need to be aware of the many issues so that you can appear intelligent and informed while meeting with these individuals. If you appear incompetent or misinformed they may cancel the site survey or the

implementation altogether. • The customer wants to know that the WLAN installation will provide a reliable link to the network for the wireless clients.

• Early adopters of wireless technology were in vertical markets. • These users were more concerned with mobility than ^ standards or throughput. • Users today are moving into more horizontal markets where mobility may be less of a concern than interoperability and throughput. • With the Cisco Aironet 340 series of products, we do I have to sacrifice mobility and roaming to gain through

and interoperability.

• One of the early adopters of wireless technology was the retail industry. • Data collection devices are extremely valuable tools for checking stock, receiving, and point of sale. • Wireless data collection devices offer the retail industry real time updates to their databases and the ability to place registers and printers throughout the store for special events (such as a sidewalk or tent sale) without

having to worry about cabling.

• Retail implementations often involve a large number of users sending data very frequently. Stores are likely to do their inventorying at night. This can mean that there will be a limited number of users during the normal store hours, which does not tax the WLAN. • But when the inventory crew comes in at night, the customer expects that the WLAN will be able to handle the demand. You need to work with the store manager to determine how often they do inventory, how many data

collection devices will be used, and what requirements are for their particular application.

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• Also ask if they will require coverage on the loading docks or inside the trucks at the loading docks. Depending on the WLAN design there may be enough RF coverage bleeding through to the outside of the buildings to accommodate this, but you should not depend upon this unless you have factored it into your design.

• Other concerns within the retail industry include the close proximity of the store to other RF devices. Some stores may stock and demo RF devices in their store. • These may include satellite systems, baby monitors, or cordless phones. Many of these may be 900MHz, but some ^ may also be2.4GHz. In any case, it is not recommended that you install Aps next to this type of equipment.

• Typically these devices have a higher output than the Aps. Also be aware that many stores use internal cordless phone systems. Encourage them to use a system that operates on a different frequency (900MHz). It is far less expensive to replace a few cordless phones than to try and design a WLAN around an existing phone system that interferes. • Retail stores may also be located in malls or strip malls where there may be other users operating 2.4GHz equipment. Examine this possibility before starting the site survey. Talk with surrounding store managers about their systems. If there are other systems in the area you will have to try and separate the stores by channel, ESSID, etc.

• Warehouse implementations present many of the same problems as we discussed in the retail market. There may be a limited number of users during the day, but when a shipment comes in, or if multiple shipments come in at the same time, many or all users may be operating at the same time.

• Stock levels in warehouses can vary on a monthly, weekly, or daily business. • Talk with the warehouse manager about when stock levels are at their highest and try to perform your site survey during this period. • If this is not possible, do your best to compensate for the potential increase in stock or put a statement into your documentation that indemnifies you if the physical layout of the site changes, to include stock levels.

• Always try to talk with the people who work in the warehouse. A forklift driver may actually have a more accurate opinion of current stock levels and when stock levels may be at their high or low points, as well as when stock levels will be at their highest. Do not assume that just because people do not work directly with the network

that they do not have information that may be relevant to your survey. • Talking to a single individual may lead you down the wrong path. Making inquiries of numerous people will hopefully give you more accurate detail. Talk with as many people as you can throughout the warehouse and inquire about stock levels and periods of high usage.

• Warehouses or distribution centers are typically dirty and have maximum exposure to the elements. Here are a few questions to keep in mind while performing the survey: -Will the APs need to mounted in sealed boxes?

-Are there freezer areas (which are difficult to cover and hard on electrical equipment)? -Do you need heated enclosures? Is there extreme humidity? -How much clearance do you have above the shelving? Will it be sufficient to mount an antenna? Or will the antenna be crushed by a forklift or the inventory that the forklift is loading onto the top shelf? .

• Healthcare site surveys are some of the most restricting, time consuming, and difficult site surveys you will ever perform.

• The primary reason for this is that almost every hospital is a multi-story building with numerous small rooms. • Beyond this there are a number of devices that may interfere with your AP, or vice-versa. • Hospitals are also prime candidates for wanting to "grill" the engineer before he can start surveying.

• The hospital staff will have many questions regarding the equipment, the frequencies used, the potential interference, and whether testing that has been done

with the products. • Never forget - hospitals are full of people whose lives depend upon the machines that are helping them survive. • Cisco's equipment has been tested with numerous pieces of hospital equipment. Contact your Cisco representative to obtain a list of the equipment. • In the event that it has not been tested against a specific piece of equipment, offer to test the AP with the equipment. • DO NOT TEST THE EQUIPMENT WHILE IT IS SERVICING A PATIENT!

• Hospitals will expect to see a competent individual who

is appropriately dressed in their facility. They are not very accepting of an individual in jeans and workboots. To help ease these concerns, many engineers even go so far as to wear a shirt and tie while surveying a hospital. • Remember, you may be required to enter many of the patient's rooms. There are large numbers of elderly people in hospitals who are concerned or even scared of your equipment. • The engineer will need to have excellent customer service skills, patience, and even kindness in order to put these people at ease. Some of these patients may have been restricted to their beds for a number of weeks or even months. They will be eager to talk to anyone who enters the room. And often the engineer in a tie is mistaken for a doctor.

• Hospital surveys also require engineers with a certain

amount of mettle. It is not unheard of to have to survey the Intensive Care Units, Infant Intensive Care Units, Birthing Units, Surgery Units, Burn Victim Units, Morgues, Emergency Room and Trauma Units. The sight of patients in this condition sometimes has a very profound effect on individuals. The engineer needs to be able to handle all of this with grace. More than one engineer has been caught in the Trauma Unit when a critically injured patient is being wheeled in. • Most hospitals can not afford to have an individual escort the engineer all day while he surveys. Most engineers are given a visitor badge and a "25 cent" tour, where they are shown specific areas where they will not be allowed without an escort, if at all. In the surgery area of hospital the engineer may be required to gown up to survey the area. And almost no engineers are allowed in the psychiatric ward or the criminal ward without a security escort.

• Because of the multi-floor configuration of hospitals, the survey must be thought of as a three dimensional

survey. While marking site maps (which are two dimensional) many engineers start to think of the survey as two dimensional. But the RF signal needs to be thought of as three dimensional, covering not only the floor the AP is mounted on but the floors above and below as well. • A hospital is a good example of a 3-D site survey, but 3D site surveys are not specific to hospitals. • Every multi-floor survey needs to be thought of as three dimensional, but this is especially the case in hospitals as they typically require a large number of APs. Because there are only three non-overlapping channels, special care needs to be taken when locating APs so you eliminate interference from other APs as much as possible. Take advantage of the non-overlapping channels when you can. • Watch out for trauma and x-ray areas where the walls may be lead-lined. Locate elevator shafts, which are usually co-located in hospitals and may be detrimental to your RF signal.

• Hospitals are also very concerned with aesthetics. Large antennae hanging from the ceiling tiles generally are not a good idea. • Patch antennae are a good choice for hospitals. They are strong antennae with good coverage patterns, allowing for fewer APs. They can be inconspicuously mounted and can even be painted (DO NOT USE A LEAD BASED PAINT!) to make them even less obvious. • Ground plane antennae are also an excellent choice. APs are usually mounted above the ceiling tiles.

• Watch out for the many devices in hospitals that can be detrimental to your signal. • Some hospitals use Spectral-ink phone systems. Most of these are 900MHz but that technology is changing. They may also have existing WLAN equipment. • Telemetry equipment is often an excellent source of interference. (Should you have to survey near telemetry equipment, consider leaving the wallet behind. Credit cards seem to be adversely affected by the equipment). • There are many, many sources of interference in hospitals. Learn to locate and work around them.

• Hotels are much like hospitals in their building construction and configuration (multi-floor with many rooms). • Hotels have started using the WLANs to support data collection devices for taking inventory of things such as mini-bars. But with the popularity of the Internet and the demand for Internet connectivity, WLANs are being installed into more and more hotels to provide Internet connectivity to hotel guests. • Beyond requiring the engineer to look at the survey three dimensionally, datarates/throughput, and security are some of the issues presented by a hotel implementation. • Hotels want to offer their guests fast, reliable internet access . This means fewer users per AP .

• Most business travelers will want to know that the data they are sending is secure and the hotel will want to know that not just anyone with an 802.11 card can access their network. • One possible solution is WEP encryption. The overhead WEP adds is minimal. • Depending on the age of the hotel, building construction may become a factor. Newer hotels will have drop tile ceilings. Older hotels will often have "hard cap" ceilings. These are ceilings that are poured concrete. There is no real, effective way to run cable across a hard cap ceiling. Keep this in mind when you are deciding where to mount APs. Older hotels may also have walls of poured concrete instead of sheetrock. This presents the same problems as hard cap ceilings. • Hotels will also have many of the same concerns as hospitals do regarding aesthetics.

• The primary concern when implementing a WLAN in an educational facility is the persons that are being educated. • More and more WLANs are being installed in grade schools, middle schools, and high schools. Students at this age have a tendency to be curious and sometimes destructive. • An antenna mounted to the ceiling in a hallway will likely not stay mounted for long. • APs have flashing lights that seem to draw in curious children. • Educational facilities, more so than any other implementation, MUST have the equipment installed in the most inconspicuous manner possible. This is the only way to insure that the equipment will be safe.

• Another problem facing the education market is that numerous schools still utilize Apple computers. • Cisco does not have a driver for the Macintosh at this point in time. • Schools with Macintosh computers may require creative solutions like the Workgroup Bridge (WGB), which allows Macs to access the network via a hub connected to the WGB. • The challenge with these solutions is that the associated cabling and/or the Workgroup Bridge may still be exposed.

• The Wireless Office presents a tremendous opportunity today. t • On the average, large offices change configurations at least twice a year. This may involve new additions or expansions, or it may involve relocating individuals or entire departments. In either case, a WLAN makes these types of moves much easier. Whether the employee is using a desktop or a laptop, all that needs to be done is to move the PC and ensure that it is within a WLAN coverage area. • This ease of use means countless hours saved for the IT department, and dollars saved on cabling or re-cabling expenses.

• Rail yards can be difficult to survey and install for many reasons. The cars themselves are very large and may be constructed of wood or metal. • Cars may be filled with a variety of materials which can limit your signal. These may include livestock, wood, metals, or perishable materials in wooden or cardboard boxes. • Inside the yard the tall cars on parallel tracks forms narrow pathways for the signal. Yagi antennae mounted on poles above the cars at either end of the yard often are the best solution, allowing you to shoot down the narrow pathways.

• Airports tend be very large single story structures. This makes the survey simpler for the engineer because the survey becomes two-dimensional. The long, open pathways also make for easy coverage. • One difficulty in covering airports is when coverage is needed outside the facility; in the baggage areas, for example. Much like warehouse installations, these APs may be subjected to extreme weather conditions and may require weatherproof enclosures.

• Another difficulty in surveying airports is the high traffic and security in airports. • While people are certainly used to seeing work crews roaming throughout an airport, it does not mean that they will be cautious around you while you are surveying. Take care not to leave materials lying about that may be stolen or may injure people running from gate to gate. A misplaced cable that a traveler trips over could result in a crippling lawsuit. • Airports are also very security conscious. Aps and battery packs, with their flashing lights and wires wrapped around them, can easily be mistaken for a bomb. This is certainly not a situation that any engineer wants to find himself in.

• Like airports, government facilities are secure facilities. Being in the wrong place at the wrong time with something that may be mistaken for a bomb could result in a spread eagle position, nose to the asphalt with an M16 pointed at the back of your head. • You may be required to obtain security clearances or may require escorts. Your vehicle may be subject to search as you enter and/or leave the facility. You may be required to submit an equipment list and have your equipment checked on a daily basis. • Beyond the security issues you will find facilities of every type at government locations, particularly military facilities. Many military bases may have one of every facility we have discussed here and you may be required to survey them.

• The single fastest growing market is the ISP market. ISPs are finding new and more effective ways to implement WLAN technology and are helping to drive some of the technology developments. Unfortunately, ISPs have unique needs that cannot always be met by the equipment. • The difficulty with ISPs is that they are trying to use equipment that is intended to be used in a LAN in a Metropolitan Area Network (MAN) environment, and sometimes even a WAN environment. They see this technology as a cheap replacement for Telco service or microwave technology. • Far too often a misinformed ISP thinks that installing a single AP on a mountaintop with a powerful omni antenna is sufficient to provide coverage for the entire city located in the valley below.

• ISPs tend to be in a hurry to install the equipment and start providing service without doing the proper research. They try to link clients and APs at distances over a mile (this requires a bridge, not an AP). They are not aware of the implications of installing an 802.11 compliant AP. They do not understand that certain parameters need to be changed to avoid having anyone with an 802.11 client attach to their AP and access their service. • You may be required to give the ISP a "dose of reality" and make recommendations on which equipment to use, how to implement the technology, and the limitations of the technology. It may not be what they want to hear, but better they know upfront than after they have promised service that they can not deliver.

• What we have presented here are some of the concerns you may face while surveying certain types of facilities. We have tried to make you aware of some of the pitfalls associated with each of these. We hope that challenges that we have listed will help to prepare you for others that you may encounter.

• One of the factors affecting your WLAN design should be the particular type of client that the customer will be using. • Some may choose to use PC cards in laptops to provide mobility to their internal staff and easy connectivity for remote users when they are in the facility. • Some may want to use PCI cards, giving users the freedom to occasionally move desktop PCs without having to worry about installing cable. • Some may use a repeater or a workgroup bridge to provide connectivity to remote users without using standard leased lines or having to worry about attempting to run fiber. Others may want to use data collection terminals. • And some may use a combination of these options.

• In an environment where the PCs will remain stationary most of the time, providing wireless connectivity is a fairly easy task. For installations of this type, users typically need "pools" of 11 Mbps coverage and will not be overly concerned with their link speed while moving. • Many customers do not fully understand the equipment that will be installed or what to expect. Some people believe that it will be a full 11 Mbps link for every user. Some question the reliability of the RF link and intend to use the wireless link on a limited basis. The truth is that most users will fall somewhere between these two.

• Remember, 11 Mbps of throughput does not mean an 11 Mbps data rate. • There are many factors that limit the link speed. Overhead, operating system, and number of users are examples. • There is more overhead associated with the RF link than there is on the wired link. Realistically, the maximum link speed will be around 7Mbps. • The Operating System will be part of this limitation as well. File transfer soeeds for a Microsoft ooeratina system are about 5.5 Mbps. Linux speeds are closer to 7 Mbps. The 11Mbps wireless link can be thought of as a 10 Mbps wired Ethernet segment when deciding how many users it can handle.

• Let's consider a typical wireless office. Most users will have an office, desk, or cube where they spend most of their day. They may have to occasionally attend a meeting, conference, or class. • For this type of application, APs need to be placed to provide 11 Mbps coverage at the desks or in the conference room. Link speeds as low as 2Mb may be sufficient everywhere else. • It is not uncommon for the user to tell you he wants 11 Mbps coverage everywhere. But after he has seen how many APs this will require, he may change his mind, at which time you may need to redo your survey. Avoid this by talking with your customer up front and addressing the issues. Find out where he thinks he needs 11 Mbps coverage and why. • Chances are that the user needs coverage at his desk, or in a conference room, but will not likely be trying to surf the web or check e-mail while he is walking between the two.

• You will need to ask the customer exactly where he needs the 11 Mbps coverage. • In the example above, the customer may think he needs APs in the corners of the office. If you do this, a large percentage of the coverage cells will be covering outside the building. • He may have a single user who he feels needs to have 11 Mbps coverage (maybe a V.P. or director). But if he has a large number of users on a lOOMbps backbone with a T-1 connection, the V.P. or director never sees 11 Mb via the wired connection anyway. So he is not gaining anything by your providing him with an 11 Mbps wireless connection. A better focus for the 11 Mbps coverage would be an area with a larger number of wireless users. •A better solution might be to move the two APs to the center of the building. This provides 11 Mbps coverage for high usage areas like the conference room and the users in "cubicle land," and provides for load balancing. Users around the perimeter get 5.5 Mbps coverage.

• Be aware of the applications that users may by utilizing. Someone who performs the occasional file transfer and checks e-mail has very different needs from someone using a CAD application across the network. •Most offices today use a client/server model frequently used applications loaded on each terminal.

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• Some companies are moving to thin clients and may have much greater bandwidth requirements. This type of setup requires a very reliable connection to the network, as an interruption of network service renders the user helpless.

• There will be "pools" of coverage at each data rate. • If the customer wants to provide certain area with coverage at a specific data rate, you may have to perform multiple site surveys. • You may have to survey at each data rate and find out where the coverage pool is for each data rate. The Cisco Site Survey Utility surveys at a given rate and does not rate shift. • You will need to map out the higher data rate cells so they can be shifted to the proper areas. You will need to map out the lower data rate coverage cells with an eye on the overlap of these cells and on frequency selection. This can be time consuming but may well be necessary, depending on your customer's needs. • Finding out ahead of time how much throughput the users will require should be something you do before you start surveying. This will be one of the factors that will help you determine where you need to place the APs.

• Copper installations can still provide higher data rates, but price is no longer a factor. A WLAN can be installed for roughly the same price as a copper-based network, and provides many benefits over a wired network. • As prices continue to come down on wireless products and throughput speeds continue to increase, wireless will continue to increase in popularity. • This may also be a factor in your design. If the customer wants to start by using a few wireless clients, and then increase the number once he is sure of the reliability, you will need to design his WLAN to accommodate this future expansion.

• If the customer intends to use data collection devices exclusively, this will change the way you perform your survey. • Most data collection devices today operate at 2Mbps Most data collection devices do not require 11 Mbps. • If the customer is using a 2Mbps data collection device with no intention of adding other wireless clients that may operate at 11 Mpbs, then perform the site survey at 2Mbps. • Make sure that all areas where the data collection devices will be used have a 2Mbps link. • Some data collection devices have the ability to rate shift Discuss the devices that your customer will be using, what abilities these devices have, and how your customer intends to use them.

• As we discussed earlier, retail or warehousing sites may have areas where large numbers of very busy users will be located. A receiving area may be one such area. As equipment is unloaded off trailers, it is unboxed and bar codes are scanned in rapid succession. The bandwidth needs are again going to be determined by the application. A screen scraping emulation sends large packets containing a lot of data, for example. If there are 20-30 users scanning barcodes and entering keystrokes in rapid succession, a single AP may not be enough. • If, for example, all of the data collection devices are talking at 2Mbps, realistically the AP is only operating at 2Mbps. This is not to say that the AP is limited to 2Mbps, but all clients are communicating at with the AP at 2Mbps. While the 11 Mbps connection might be sufficient to handle the 20-30 users, the 2Mbps may not. You will have to examine the packet size of the application and the number of users to determine if you will need extra AP's in this area.

• Data collection users are also highly mobile users. That is the advantage of the wireless data collection device. It enables the end user to freely roam throughout the facility and scan items instead of having to carry the item to a scanner which is attached to a fixed terminal. •Coverage must not have holes and must have enough overlap between APs to offer truly transparent roaming.

• Some data collection devices are mounted to forklifts, which can move throughout the facility very quickly. • A driver may scan a barcode and then enter the quantity as he is driving away. Take into consideration that the forklift driver does not understand the technology, and usually doesn't want to. He simply wants a system that works. It is your job to provide him with this system. • Part of this will be the application's ability to handle a mobile user and the occasionally dropped packets that go along with that mobile user. But by providing the most seamless coverage possible, you will ensure that the application will have fewer problems and work successfully.

• What we have presented are two of the most common implementations of WLAN's, the Wireless office and Data Collection. The principles involved center around whether the user will be stationary most of the time and occasionally mobile, or a highly mobile user who is constantly on the go. • Understanding how the customer intends to use the WLAN is very important to understanding how you will need to survey. • Some of this information can be obtained through the presite survey form. But a good site survey engineer realizes that the best way to understand what the customer needs is to interface with the customer.

• A survey kit should contain at least one of each type of PCMCIA card. • Survey with the card that the client intends on using. If the client is planning on mounting a terminal inside of a crane and attaching it via an LM card with a 5.2 dBi omni, you do not want to survey using the attached end cap antenna on the PC Card. • Make sure that your kit includes the adapters for the LM card (MMCX – RP-TNC). This way you will be able to attach a variety of antennae to the LM card and emulate your client’s desired installation.

• It is always a good idea to carry more than one AP. • Many are the engineers who have had a mishap with their only AP (AP's do not usually perform very well after being dropped form a lift or ladder). • An extra AP allows the survey to continue without having to wait for a spare to be shipped.

• AP's require power to operate. There will not always be power available nearby while performing a site survey. A good battery pack will last for at least 8 hours, allowing the engineer to survey all day without having to recharge. • Also recommended is a fast charger for the site survey tool. If a laptop is used, spare battery packs that can be charged separate from the laptop are always recommended. Wireless PC Cards require a constant source of power while surveying and may reduce battery life to less than two hours. Li-on batteries power the unit longer, charge more efficiently, and are lightweight.

• There is no single antenna that is perfect for all applications. A variety of antennae are offered because they are needed. Antenna choice and placement is, in many cases, dictated by the customer. A customer may not want the antenna to be visible, or it may be located in a high traffic area. By carrying a variety of antennae you will be prepared for any situation. The minimum collection of antennae should include (but is not limited to): 2.2 dBi "Rubber Duckies" 5.2 dBi Mast Mount 6.0 dBi Patch 13.5 dBi Yagi

5.2 dBi Ceiling Mount 5.2 dBi Ground Plane 8.5 dBi Patch 5.2 dBi Diversity Pillar Mount

• If you will be performing site surveys where you are aware that you will be using an antenna that is not in you kit, carry that antenna as well. Always survey with the antenna you intend to use. Do not use a different antenna and attempt to "guesstimate" the coverage. You are performing the site survey to take the guesswork

out of the installation.

• You should always carry an AP mounting bracket (when available). The kit should also contain various mounting solutions for the bracket (beam clamps, C-clamps) as well as mounting brackets for each antenna (when available). Beyond this you must again be creative. Zip ties, duct tape, bailing wire, electrical tape, two sided tape, velcro and paper clips are common components in a good engineer's kit. • During a survey there is no bad mounting solution except the solution that does not properly secure the AP, battery pack, and antenna. Not only might you damage your equipment, but you risk injuring yourself or others when the equipment comes crashing down. (This also fails to instill any measure of confidence in the customer as he watches the "trained professional's" expensive equipment shatter to pieces on his warehouse floor).

• Once the AP placement is determined, it will be necessary to mark the location. • Location markers should be very bright and resistant to dust, grease, and water. • Surveyor's tape works very well and comes in a variety of bright colors. • Brightly colored signs allow you to not only mark the location of an AP, but give some detail as to how the AP is to be configured and mounted, and can give a point of reference to anyone reading the site survey report. • Markers should be sturdy but temporary.

• In order to provide the customer with the details needed to bid for the installation, you will have to provide many measurements in the site survey report. And these measurements need to be as accurate as possible. • If you guess the Cat 5 run to be 300' and it turns out to be 380', the customer will be very unsatisfied. • Your kit should include a measuring wheel (for measuring cable distances). Many people include more advanced equipment, such as laser measuring devices and range finders. These are all viable options, but a measuring wheel will get you what you need. For measuring vertical distances, a rope marked in 10' increments will allow you to accurately judge distances floor to ceiling. • Counting floor tiles and/or ceiling tiles is not a good measurement of distance!

• Surveys should always be performed equipment that will eventually be installed.

using

the

• This can sometimes be difficult with splitters, lightning arresters, and extension cables. • Instead of carrying one of every length of cable, lightning arresters, splitters, and other accessories, some engineers outfit the site survey kit with an antenna attenuator. The antenna attenuator allows you to inject varying amounts of loss without needing the actual accessories.

• The most important part of a site survey is the site survey kit. No matter how talented the engineer may be, it is impossible to perform a site survey without the proper tools. • It is recommended that a site survey kit be a portable unit. For ease of use, a hard plastic case that rolls and can be checked as luggage is the best and most common package. • Often site surveys are requested on very short notice, and the ability to carry the carry the case in the trunk or backseat of a car, or check it as luggage allows the engineer to travel with his equipment and solves the problem of the kit being lost or detained when shipped. It also allows for quick deployment of an engineer.

• Today's IT professionals are generally already overworked, and do not want any project that may increase their workload. • They want a site survey that provides in detail where the AP's are to be located, how they will be mounted, how they will be connected to the network, and where any cabling or power may need to be installed. • By providing the customer with a detailed site survey report, the IT manager can turn the necessary portions over to a local contractor who can install the cabling that may be needed to provide the WLAN connectivity to the network. At the same time, preparations can be made on the customer's network for the upcoming installation. • The IT manager's part is limited to turning over the work to a trusted local contractor. You have saved him a lot of work. He will remember this in the future when he needs another site survey.

• In order to generate a detailed site survey report, you will need to get to know your customer's wired network. We will list some of the areas of the network you should investigate. The customer wants to be confident that the SE is capable and knowledgeable. LAN Infrastructure • You will need to work with someone in the customer's IT department to discover the layout of the customer's network. Generally, it is a good idea to start with a discovery of the LAN topology. It will be helpful if they can provide you with logical drawings of the network. • Know your topologies - There are many different topologies but most companies today use some sort of star topology for their network. It may be a clustered or distributed star. Understand where the components of the network are located. Have the IT representative show you where the servers are located, where the connectivity points are (cabling closets with hubs, switches, routers, etc.), and where the cabling is run throughout the building.

• Look into the media types that make up the network. The customer will most likely use some type of copper UTP cabling for most of the runs. Copper can be run to a maximum distance of 328 feet without a repeater or hub. Fiber can be run for miles if necessary. • Some facilities use fiber cabling. Most of these sites use a combination of fiber and copper, with the fiber acting as the main backbone of the network and copper runs to the desktop. • In the event that the facility uses fiber cabling throughout, make sure to advise the customer that the AP's only provide RJ-45 connections and that a media transceiver will be needed for each of the AP's. This can be a significant cost.

• Ask the IT representative about the operating systems for the clients and servers and ask which protocols are being used on the network. • Ask specifically which protocols will be sent over the WLAN. You may need to filter out all protocols that will not be used on the WLAN to cut down on unnecessary wireless traffic. • Make sure that the customer is aware that not all operating systems are supported (drivers are not available from Cisco for Linux or Macintosh systems yet).

• Once you understand the topology and the media, look into the network components. • Hubs may be 10Mbps, lOOMbps, or 10/100 hubs. The Cisco AironetAP's have 10/100 auto-sensing ports, and will work on either port, but whenever possible you should try and connect via a lOOMbps capable port.

• If the customer uses switches you will need to find out how these switches are set up. • Switches have the ability for each port to represent a "virtual LAN" (VLAN). Ports may be grouped together to form VLANs. • Many people today are not aware of these abilities and try and use switches just as they would hubs. They think that all devices plugged into the switch will be able to communicate. • This may or may not be the case depending on the default settings of the switch. • Switches can stop broadcast packets.

• Switches are designed for wired networks with stationary users. Switches are not set up to handle mobile users. • If the switch sees each port as a VLAN and there are AP's on each port, the switch is not set up to handle users moving from one VLAN to another. • Cisco Aironet AP's are set up to get around the shortcomings of a switch. When a client roams from AP1 to AP2, AP2 sends a directed packet to AP1 letting it know that the client is now registered to AP2. AP1 can then forward any packets that it has for the client to AP2. • You may also want to consider the need for a design using a single VLAN spanning multiple switches as your roaming area with multiple APs. This allows the best continuum of uninterrupted connectivity to allow almost all applications to work seamlessly. This requires that you be careful about the overall amount of ambient broadcast/multicast traffic in the same area, and the effect this may have on all nodes. • Another solution is to use MobilelP. This allows the VLAN sizes to be smaller as Mobile IP will take care of maintaining connectivity as the node(s) cross IP subnet boundaries.

• The customer's application may not be set up to handle anon-contiguous broadcast domain, i.e. one separated by IP routers.

• One potential solution to this problem is to group the ports with AP's connected to them and the port the host is using into a single VLAN. This may or may not work for your customer, depending on many factors such as topology and application needs.

• Another potential solution is to network all of the AP's to the same hub that the host uses. Cable distance limitations may make this difficult. • Still another solution may be to network all of the AP's together via hubs and have them connect to same hub the host uses. This is not a viable option if the host is remote. Note: This solution may present problems for some people. Under the 802.3 standard, when using a switch, you should not extend beyond two hops. (Remember, the wireless link between client and AP is not considered a hop.) This would be three hops. You may be required to remind (or explain) to your customer how his switch works and inquire if this will present a problem for his WLAN. • These problems are seen most frequently in installation using data collection terminals, where a user may scan a bar code while standing in one cell and then wander into another cell while keying in the

quantity and pressing Enter.

• Sometimes problems arise with switches because of the tables they build. • Some switches drop addresses from their tables after a period of inactivity. When the client tries to connect, the AP is no longer in the switch tables and can not pass traffic to the network. • Typically, this is not a concern. AP's are generally not installed and used infrequently enough for this problem to appear. But in some installations, an AP may be installed in a back corner of a warehouse or retail store and only used during certain times of the year. In this case, it may be necessary to lengthen the timeout values on the switch or add a static entry. • If the customer decides to use DHCP the switch will have be set to handle the DHCP requests. DHCP requests are a type of broadcast packet and can be stopped by the switch. If the switch is not configured properly, the clients will be unable to obtain an IP address.

• Routers present internetworking considerations similar to switches. Like switches, routers do not pass broadcast packets. Again, this may present a problem for the application or for clients trying to use DHCP. • A router may also indicate that they intend to use a remote host. If this is the case, it may be necessary to enter a static route in the router.

• Bridges can also present challenges because of their tables. Most bridges used today build dynamic tables. • Some facilities may need to build their tables manually, sometimes by choice or sometimes because they are using older bridges. • Most IT personnel are not eager to have to work with these tables. It may be necessary in order for the WLAN application to work properly, especially if they will be accessing a remote host. • Most modern day bridges support dynamic learning with support for static filtering. If the customer is still using equipment that requires the manual building of tables, it may be time for him to consider upgrading the equipment.

• Remember that there is the possibility of running out of DHCP addresses in mobile VLANs. To accommodate this, keep lease times low to prevent address depletion. • Make sure to take into account the least common denominator that the application (s) may demand in terms on network bandwidth. This will allow you to provision the infrastructure and the AP cell sizes and datarates. • For example: If you have an application that is sending out a multicast stream at 1.5 Mbps, a 1Mbps WLAN connection would be insufficient. The minimum datarate for such an application would have to be 2Mbps. This would ultimately mean surveying at 2Mbps and smaller cell sizes.

• Try to identify potential problems up front and discuss how these issues will be handled. This will potentially save the customer a lot of time and trouble during the installation. • If the customer is aware of these issues, they can be handled before the installation. These are not issues the customer wants to find during the installation, or during the "go live" period. • By addressing potential problems and being proactive instead of reactive, you and your survey appear as the strong, reliable source during installation, instead of the weak link. • Your firm's reputation for site surveys is one of your strongest assets and should always be protected. One bad site survey can hurt your business for months or years to come.

• As you are surveying a facility and deciding on location for the APs, you should also be looking for ways to connect the APs to the network. • By now you should be aware of the network layout and components and have a good idea of where and how you can interface with the network. • Most SEs are not experts on cabling. Your job is to perform the survey and make recommendations. These recommendations need to cover the cable associated with the APs. • Because of this, you will have to have some knowledge of cabling. Here we will address some of the issues surrounding cabling and make you aware of the items you should be concerned with during the survey.

• The most frequently used cable for today's networks is Category 5 (Cat 5) unshielded twisted pair (UTP). • Cat 5 cable consists of eight strands of copper, grouped in pairs. Each pair is twisted to help avoid cross-talk. The four pairs of wires are housed in a PVC sheath. • Most networks use two of the four pair of wires. All four pairs are punched down onto the connector, but only two are actually used. • UTP means that there is no additional shielding for the pair of wires inside the PVC sheath. Cat 5 UTP cable can be run a maximum distance of 328 feet or 100 meters.

• Cat 5 is also available in Shielded Twisted Pair (STP). • This cable has an extra layer of shielding inside the sheath, The reason that Cat 5 UTP cable cannot be run over 328' is because of attenuation (signal on the wire becomes weak or distorted). Part of the reason for the distortion is interference. By using a shielded cable, there is less interference and less attenuation, allowing you to run longer distances. • STP is generally not as widely used as the UTP. Instead, Cat 5 UTP cable is run to its maximum distance and then plugged into a repeater, hub, or switch, where the signal is then rebroadcast down the next length of Cat 5 UTP. • Another option is to use Fiber Optic cabling for distances that exceed 328'.

• Cat 5 cable is available in plenum and non-plenum. Building construction, as well as local and state building codes, will determine which type of cabling must be used. • The plenum is the space between the drop tile ceiling and the true ceiling. • In a plenum environment, this space is used for air return. In the event of a fire, the PVC sheath can melt and give off toxic fumes. • Since network cables are traditionally run in the plenum, toxic fumes will then be circulated throughout the building. Therefore, plenum cable must be used in these facilities. All other equipment installed (APs) must also be plenum rated. Currently Cisco's 340 series APs are not plenum rated. • Plenum cables have a different sheath that will not melt as easily and will not give off toxic fumes. Plenum cable is easily identified. • The sheath of plenum cable is much stiffer and harder to work with than standard Cat 5 cable. The cable will also be marked with a code (CMP, for example, indicates a plenum rated, unshielded cable).

• Some easy ways to identify a plenum environment are "egg crate" ceiling tiles, a lack of insulation above the ceiling tiles, and firewalls. Some local and state building codes require plenum cable regardless of the environment. • A non-plenum environment is one where the air return is ducted. When the air return is ducted there is very little chance that the toxic fumes could spread in the event of a fire. • In this type of environment it may be suitable to use a general purpose (PVC) type cabling. • Some indications of a non-plenum environment are an abundance of duct work above the ceiling tiles, a lack of firewalls, and insulation above the ceiling tiles. • These cables will also have identifying codes (CM, for example, indicates a non-plenum unshielded cable).

• Firewalls are usually easily identified. • They will be concrete, cinderblock, or brick structures that extend the full width of a room or passageway, and extend from floor to ceiling. • There are no breaks in firewalls. Firewalls are designed to contain a fire to a specific area by acting as a barrier. • It may sometimes be necessary to go through a firewall. In this event there are procedures for penetrating the wall. These procedures must be compliant with the National Electrical Code. You can obtain a copy of the NEC from local electrical suppliers. • For this reason you should make a note in your survey report of any area where your design will have to penetrate a firewall.

• Another reason to make note of firewalls is that they will affect your RF signal. • Many facilities have firewalls with doorways. The doors are specially constructed and sealed to withstand a fire. Other than their heavy construction, these doors are not easily identified. • If you think that a set of doors may be part of a firewall, check and make sure. If they are, survey with the doors closed. • Closing the doors will have an effect on your coverage. Just because the doors are open when you are in the facility, do not assume they will always be left open.

• Risers are often referred to as "wiring closets". • Risers are areas of the building where cabling, conduits, and plumbing may be run from floor-to-floor. • Most often, risers are stacked on top of one another, making it easy to run the height of the building. • All four walls of a riser act as firewalls, as well as the floor and ceiling. And like firewalls, there are standards for penetration. • Make a note of risers for the same reasons that you would firewalls. It will require penetrations that meet NEC standards and will require plenum-rated equipment.

• Always design and measure cable runs in straight paths. • If a cable running north-south needs to be run in a different d^recjion, make a 90 degree turn. Do not run the cable at an • Never measure the distance from the point of network connectivity to the AP as "the crow flies". • If you do and the customer gives your report to a local contractor for an estimate, the estimate could be wrong. • Also, the cable run may be too long and require a different type of cabling.

• Always calculate for a "service loop" on either end of the cable run. Service loops are usually 10 feet. • This gives the contractor some "play" in the cable in case the cable has to run around some unforeseen object, or in case the cable has to be terminated numerous times. • Runs that are measured at anything over 300 feet should be carefully examined. From the floor, it is difficult to judge the exact distance. • Also calculate a "fudge factor." Different SEs have a different percentage that they use here. Adding 15% is usually enough to insure that there will be enough cable to get around unforeseen objects. • Make a note of your estimated "fudge factor" percentage in your report. Otherwise, the contractor may add his own and decide the run will be out of specification.

• The number one rule when designing the cable portion of your WLAN is to avoid fire hazards and to avoid creating a fire hazard. • Design your cable runs properly. If the customer chooses to ignore your recommendations, that is his prerogative. This is why accurate documentation is necessary. In the future you may have to prove that the installed cabling is not what you recommended. Without proper documentation, this will be very hard to do. • But if you design a faulty system and he installs according to your recommendations, you could find yourself in a lot of hot water. • We have given you a very brief idea of some of the questions and concerns you should have in your mind while performing a site survey. By keeping these things in mind while you survey, you will be able to design a WLAN that will not only be reliable, but also easy to install as well. A few extra minutes as you are doing your survey can save your customer hours of work.

• When you have decided where the APs will be mounted, you will then have to decide how the APs will be mounted. • Much like mounting the AP for a site survey, there are an infinite number of ways to hang the AP using a variety of resources. • Here we will look at some of the most common methods for mounting Aps and some of the general concerns associated with mounting an AP and the antenna.

• Cisco 340 series APs do not ship with a mounting bracket. • The APs have two slide-mount holes for mounting. These holes can be used for any surface where it is possible to mount two mounting screws. • Screws drilled into concrete will be fairly stable and should provide a secure mount for the AP if done properly. Drywall or wood may be less secure. • It is recommended that all APs be mounted with extra measures to ensure the safety and continued operation of the AP. • A proper mount for the AP means less chance of down time. Loss of connectivity means lost time to the workers.

• Mounting brackets are available from third parties. • A simpler, but less secure solution, is to fashion some sort of mount. This can be done using many of the same items you carry in your site survey kit. Here are some ideas: • When mounted on a pole or column, the AP can be zip tied to the pole or column. Use heavy-duty zip ties. Heavy-duty zip ties can be as wide as half an inch. If using these zip-ties, make sure not to cover up the indicator lights on the AP. • In the diagram above, the AP is mounted in what appears to be an upside-down position. This position allows the indicator lights for the Ethernet port to be seen from the floor. • Whenever possible, Aps should be labeled with the Name, IP address, Channel and SSID. The letters need to be easily readable from the floor in the event that the AP

requires troubleshooting.

• If the column is too large for zip-ties, another option is to mount a piece of a 2x4 to the column. • This can be done by using screws or bolt to attach the wood to the column. Another option is to use a silicone or glue to mount the board to the column, like Liquid Nails. DO NOT USE THE LIQUID NAILS TO MOUNT THE AP DIRECTLY TO THE COLUMNI In the event that the AP needs to be removed or replaced, it will typically be destroyed. • The AP is then mounted to the wood using screws and secured using zip-ties. If the piece of wood extends beyond the width of the column, the zip ties can be wrapped around the ends of the wood and across the face of the AP. • Otherwise it may be necessary to attach a mounting base for the zip tie on the board. If you use the mounting bases, be sure to secure them to the board using a screw. Do not depend on the sticky tape on the bottom of the mount. The AP will probably outlast the sticky tape. • The use of a piece of 2x4 is also good for concrete ceilings

and walls.

• When mounting to a rafter or beam, the AP may be zip tied to the rafter or beam. • In some cases, it is not possible to wrap a zip tie around the rafter or beam. If this is the case, you may use the piece of 2x4, secured to the beam with beam clamps. • You may also use a beam clamp to secure a mounting plate to the beam and then attach the AP to the mounting plate. • Always make sure that the 2x4 is securely mounted to the structure before mounting the AP.

• If surveying with the "rubber ducky" antennae, make sure to survey with them in the position they will be mounted. In the examples shown on this page and the prior two pages, the antennae would be pointing straight down. There are different coverage patterns above and below the antenna. If you survey with the antenna in one position and mount it in another position, your coverage may be different than what you

expect.

• Every AP will have an antenna attached to it.

• Most antennae are either shipped with a mounting bracket or a mounting bracket is available as an option. The challenge is that most antennae are designed to be mounted in a certain way. • A 5.2 dBi mast mount antenna is designed to mounted to a mast and is shipped with the hardware to mount the antenna to a mast. • In order to mount the antenna to an I-beam, you may need some ingenuity. Standoff brackets are available, but these are not designed to be mounted to an I -beam, either. Some installers use zip ties, beam clamps, or bolts to attach the standoff brackets to I-beams and then mount the antenna to the bracket. • If you intend to use a mast mount antenna indoors, make sure it is mounted as shown above. The antenna is intended for outdoor use and designed to be mounted with the metal sleeve on the bottom. For indoor use, invert the antenna. • Be creative. Modified brackets can be used for a variety of antennae.

• Just as with the APs, always make sure that your antenna has a secure, solid mount. • Make sure that the antenna will hang properly when mounted to the base. If you surveyed with the antenna in a vertical orientation and it is mounted to an insecure base, it may hang at a 45° angle, changing the coverage pattern. • Do not hang antennae by their cables. The cable is not designed for this and may eventually break or suffer internal damage that cannot be seen. • Another reason not to hang antennae by cables is that this would change the coverage cell. Also, the antennae may sway when the air conditioning comes on, providing a moving coverage cell.

• Sometimes antennae may be used or mounted in an unusual way. • In some circumstances, a Yagi or Patch antenna mounted very high and pointed straight down at the floor is the best solution. • If you intend for the antenna to be mounted in an unusual way, make a note of it in your report. The installer may not understand your intent and mount the antenna per its specifications, changing the coverage pattern.

• All APs require power to operate. You should provide details in your report about how and where the APs will tap into the electrical system. • APs should be powered from a 24 hour, input power source breaker. This may be shared, but a dedicated source is preferred.

• Familiarize yourself with various types and brands of electrical equipment. You do not need to be an expert on these, but should be able to identify them. This will allow you to be very specific in your report when detailing where the AP will get it's power from. For example, you report may state that "AP #4 will receive power from the Square D box on the North wall of the Shipping Area. Distance from the Square D box to the AP was estimated at 145 feet." • By defining the location and brand of the breaker box, the electrician will be able to easily identify the box and install the associated wiring. • Also be familiar enough with the breaker panels to identify if there are available breakers or if the breaker is full. If you specify a specific box to be used and there are no available breakers, this could present a problem, especially if your report is used to generate a quote for the electrical work.

• Electrical workboxes should be mounted face up such that the weight of the AP transformer can rest on the faceplate. The transformer should then be secured to the faceplate or workbox using zip ties. • Do not mount equipment to electrical conduit, plumbing, or ceiling supports. This is usually a code violation. • There could also be a leak in the plumbing, or extreme temperatures in the pipe. • Conduit could become electrified in the event of an electrical short, and the electrical wiring in the conduit is a good source of EMF. • Mount the equipment as far away from these as possible.

• Sometimes APs may be located in areas where they are subject to extreme moisture, temperatures, dust and particles. These APs may need to be mounted inside a sealed enclosure. These enclosure are generally referred to as "NEMA enclosures". NEMA stands for National Electronics Manufacturers Association. NEMA has a rating system for these enclosures. The ratings are as follows:

• Type 1 - Intended for indoor use primarily to

provide a degree of protection against (hand) contact with enclosed equipment. Usually, a low cost enclosure but suitable for clean and dry environments. • Type 2 - Intended for indoor use primarily to provide a degree of protection against limited amounts of falling dirt and water. • Type 3 - Intended for outdoor use primarily to

provide a degree of protection against windblown dust, rain, and sleet; undamaged by ice which forms on the enclosure. • Type 3R - Intended for outdoor use primarily to provide a degree of protection against falling rain and sleet; undamaged by ice which forms on the enclosure. • Type 4 - Intended for indoor use primarily to

provide a degree of protection against windblown dust and rain, splashing water, and hose directed water; undamaged by ice which forms on the enclosure. • Type 4X - Intended for indoor or outdoor use primarily to provide a degree of protection against corrosion, windblown dust and rain, splashing water, and

hose directed water; undamaged by ice which forms on the enclosure.

• Type 6 - Intended for indoor or outdoors which occasional temporary submersion is enclosed.

• Type 6P - Intended for indoor or outdoors which occasional prolonged submersion is encountered. Corrosion protection. • Type 12 - Intended for indoor use to provide a degree of protection against dust, falling dirt, and dripping non-corrosive liquids. • Type 13 - Intended for indoor use primarily to provide a degree of protection dust, spraying of water, oil, and non-corrosive coolant.

• The NEMA enclosures most often used for wireless

networking products are Type 2, 4, and 4X. Some specific requirements might require Type 12 or 13.

• These types of enclosures can be purchased through local hardware and electrical supply stores. Unfortunately, when purchased through these type of supply stores, the NEMA enclosure is little more than a sealed box. There are no external antenna connectors, no internal mounting standoffs, and no internal power supply.

• Almost no NEMA enclosure is available off the shelf with an internal power supply. • Mounting for the AP inside the enclosure can be fashioned just as you would when mounting an AP without an enclosure. • Power will have to run to the enclosure and an electrical workbox (plug) installed inside the enclosure. • In order to attach an external antenna (an antenna mounted inside the box is not very effective), a bulkhead extender will need to be installed. This is a simple connector that connects to the AP inside the enclosure and provides an antenna connector on the outside of the enclosure. • Make sure that any holes drilled into the box are sealed. If even one hole is left unsealed then the integrity of the enclosure has been compromised. Antenna connectors should be mounted to the bottom of the enclosure to provide as much protection from dripping condensation as possible. It is also a good idea to seal the antenna connection with a product like Coax Seal.

• Pre-fabricated NEMA enclosures with antenna connectors, standoff brackets, and surge protectors are available from third parties. They are more expensive than a standard NEMA enclosure, but provide better protection for the AP and can save either you, your customer, or the installer a great deal of time and trouble. • Special NEMA enclosures are also available that are temperature controlled and make use of solar panels to power the equipment. • Make sure that if you use a NEMA enclosure it is securely mounted. A NEMA enclosure that measures two cubic feet can weigh as much as thirty pounds. If the enclosure is not properly secured it could fall, injuring someone, damaging equipment, or destroying the connected conduit for the power. Exposing the wiring creates a potential fire hazard.

• In this section we have made you aware of some of the issues surrounding mounting and powering the APs. • You are not expected to be an electrician or to know all of the local, state, or federal codes. You do need to be aware of the ones that apply to you and can affect your survey. • Keep all of these issues in mind as you survey. It will save both you and the customer time in the long run. You will make better decisions when surveying the first time, instead of having to re-survey because you were not paying attention to potential mounting or power problems.

• Sometimes you may not be able to mount an antenna to the AP using the existing connecting cable. • Use of these extension cables will result in signal loss. You suffer a loss of about .5dB for every connection. • For example, an antenna extension cable will have to be connected to the AP (.5dB loss) and to the antenna (.5dB loss). This results in 1dB of loss without even considering the cable itself. • Current extension cables available from Cisco have approximately 4.7dB of loss per 100 feet. • These cables are 9913 style, and the total loss for a 100 foot extension cable is estimated at 6.7dB, including cable loss and connector loss.

• Keep this loss in mind if you are considering using an extension cable. • It is not recommended that you use the 100 foot extension cable with the 340 series products. The reason is that there are virtually no antennae that would be used indoors that could suffer this amount of loss and still be effective. Any antennae with less than 7dB of gain would be completely ineffective if used with the 100 foot cable. • A better idea is to run the Cat 5 cable to the antenna location and mount the AP as close to the antenna as possible. In the event that you must use an antenna extension cable, use only as much extension cable as you need. • The cables are available in 25, 50, 75, and 100 foot lengths. These cables fit most needs.

• If you need a specific size cable you can order custom made cables from cable manufacturers. • For very long distances (in excess of 75 feet), you may want to consider a different type of cable with a lower loss. One such cable would be LMR600. This has a much lower loss than the 9913 (4.2 dB vs. 6.7dB) and can still use the 9913 style connectors available through Cisco. • Cisco does not offer an LMR600 extension cable (yet).

• Cisco offers the RPTNC connectors for 9913 and RG-58 cables. Do not attempt to use RG-58 cable for an extension cable. The amount of loss in this type of cables renders it useless as an extension cable. • The RG-58 connectors are available in case the original connector on an antenna is damaged and needs to be replaced. Most Cisco antenna connection cables are RG58. • Some installers try to substitute extension cables with an N-style connector. These are widely available. An RG58 "jumper" is used to connect to the AP and antenna. • Although the extension cables with the N-style connectors are more widely available, and possibly less expensive, this solution would not be worthwhile in the long run. • The jumper cables will have an RPTNC connector on one end and an N-style connector on the other. One jumper is needed for connection to the AP, and another

for the antenna. This results in a loss of as much as 3.5dB or more.

• Earlier we discussed the use of a splitter for certain applications.

• Splitters certainly have their place and can be very useful if installed properly. But you need to understand the ramifications of installing a splitter. • Most splitters use N-style connectors. This is because very few splitters are designed for WLAN equipment. • Most splitters available today are for use with broadband equipment, much of which uses N-style connectors. • N-style splitters are implemented with WLAN equipment by making use of jumper cables. These jumper cables are 9913,notRG-58. • Three jumpers are used with the splitter. A three foot jumper connects the AP to the splitter. Then two longer jumpers (usually 15-20 foot) are used to connect the

antennae to the splitter.

• The splitter will add about 4db of loss. • If you manufacture your own cables and they are longer than the supplied cables, then the loss will increase (depending on what type of cable you use). • We mention 4dB loss as a general guideline when deciding if the use of a splitter will be appropriate. See the technical specifications of your specific splitter for exact measurements. • Each antenna connected to the splitter suffers the 4dB loss. This means that while the use of a splitter and a second antenna may allow you to cover more area, it will not double your coverage area.

• Here we have discussed some of the accessories that are available for use with the Cisco 340 series products. • These accessories are designed to be used for special applications and are not meant for general use. Again, in an in-building LAN, installing another AP is often the best solution. • Know how these accessories are intended to be used, and understand their limitations. This will allow you to decide, when, if, and where you may want to use them.

• Once the customer has decided to have a site survey done, you will need to have him fill out a pre-site survey form. • The pre-site survey form will help you determine what type of survey you will be conducting, how many days it will take, what equipment you will need to bring, and what questions you will need to ask during your walkthrough. • A pre-site survey form is your introduction to the customer's facility, so make sure that you gather all of the information you need in the form. This is a general information gathering form. • We have provided you with a sample form. You will have to create a form unique to your company that fits your needs.

• The product that you will be producing is the site survey report. • All of the work that you have put into surveying is meaningless without the site survey report. This is what the customer is truly paying for. • The report is what the customer needs to move forward in installing his WLAN. He is depending on you to provide him with all of the information he needs to be able to gather the materials and make the necessary adjustments to his network. • Make sure that your report includes all of the information that you have gathered.

• Be as specific as possible in your report. Chances are that you will not be doing the installation. • Keep this in mind as you are writing your report. It should be clear, concise, and easy to understand. • You should think of the report as protection for both you and the customer. In the event of a disagreement or problem, a good site survey report can prove that you completed the site survey per the customer's requirements at the time of the survey. • Put the date of the site survey on your report. • An installer may be handed a site survey report and asked to install the equipment. If there is a date on the survey that is a number of months or years old he may question the survey's integrity.

• When describing AP locations, be as specific as possible. • Use objects and identifiers to explain exactly where the AP is to be located. If the AP is to be located in an aisle, specify which aisle, and where that area is located in the facility. Specify exactly how the AP is to be mounted.

• If you have marked the location, explain what you used to mark the location. This way the installer knows what he is looking for and does not have to guess. • Even more important than the AP location, specify with as much exactitude as you can where the antenna is to be located. • "On the wall above the doorway" is not enough. • "On the wall above the doorway, two feet left of EXIT sign" might be a better explanation. • Do not use objects that may be temporary as markers. If the object has moved before the installer arrives, he may not be able to find your location and may mount the antenna in the wrong

location.

• Describe how the antenna is to be orientated. • If the antenna is omni-directional, you might mention that the antenna is to be mounted vertically, with the cable at the top. Not all installers will be familiar with the equipment and how it is designed to be mounted. • If the antenna is directional, describe the direction in which the antenna should be orientated. A patch antenna might be described as "facing north" or "directed at the nursing station at the end of the hall". • The more directional the antenna, the more important your description.

• Describe the facility, its construction, and its contents. Make mention of the square footage. • Discuss the tools you used to survey and how you performed the survey. • Describe the settings that you used in the survey, to include datarates, channels, packet size, and thresholds. • Talk about the coverage for each access point and detail the coverage in an included diagram. • Also mark areas where there is no coverage needed. The customer could come back later and tell you he wanted coverage in an area where he previously claimed he did not. • If you do not mark the areas where coverage is not needed (or describe them in the report) you have no way of proving that you were instructed not to survey the areas for coverage. • Have the customer sign and return a copy of the report for your records.

• Add sections that discuss proper mounting of the APs and antennae. Detail the specifications for providing power to the APs and how the electrical workboxes should be mounted. • Discuss the proposed cabling runs (power and networking) including where and how they will attach to each system. • List the system components. List the network media type and components that you suggest connecting to. List the WLAN components that you are proposing for installation. Discuss the network topology and planned implementation of the WLAN topology. • If the customer discusses future expansions or WLAN client upgrades with you, explain his intent in your report, and any problems that the upgrades may propose. • Explain your objective for the site survey. What are the customer's needs and expectations?

• Include a list of the parts that will be needed. • Include the total number of APs for the install and recommend that a spare be kept on hand in case of emergency. • List the total number of antennae needed. • If possible, list network components that you have proposed. • Some SEs go as far as to list the amount of network and power cabling that will be needed for the job and make recommendations on the type of cabling to be used. • Include diagrams showing the facility, AP locations, and proposed cable runs. • Whenever possible, include photos. Today's digital cameras are relatively inexpensive. A photo of the AP location or proposed antenna installation makes it very clear how and where the equipment should be installed.

• List the contacts for each of the companies involved. These may include manufacturer, reseller, customer, and services companies. List names, addresses, phone and fax number, and e-mail addresses. • In this section we have made suggestions on some of the items that should be included in you site survey report. Each report you will do will be different based upon your survey and your customer's needs. Included is a site survey report of an imaginary facility. This should give you a good idea of how a site survey report should look and what kind of documentation you will be expected to produce.

• When a radio wave strikes a solid surface, it is reflected in the same way that a light wave would be. • The reflected waves may have a different polarization depending upon the angle at which the waves are reflected. • Directional antennae can be used to reduce the amount of reflected waves. A directional antenna will focus the RF energy in a single direction, leaving less radio waves to be reflected from objects to the side or behind the antenna.

• When a radio wave bounces back on itself 180° degrees out out phase, it creates a "null" or dead spot, where the combined siognals virtually cancel each other out. • Nulls are a fact of life with RF. Nulls will be all around you, but their positions may be constantly changing. As a forklift drives through a warehouse, or a person walks through an office, radio waves may be reflected off of these moving surfaces. As the location of the forklift changes, so do the nulls. • A problem can occur when a null is stationary (RF wave reflected back on itself by a stationary object). If the antenna is located in a null, their will be poor reception. Use diversity antennae to overcome nulls. • When a single antenna is used, the AP may have to be relocated to overcome the null.

• If the RF wave is unable to penetrate an object it will suffer from what is called diffraction. • The RF waves may pass over, under, or around the object, still providing coverage on the other side of the object, but there will be an area directly behind the object where there is no coverage. • This area is most commonly known as an "RF shadow". If there are other objects nearby, reflected RF waves may fill in the the area behind the object, eliminating the shadow. • The only way to know for sure is to survey the area.

• After you have discovered possible trouble areas, examined your customer's application needs, and talked with the IT staff concerning their network, it will be time for you to start the survey. • Make sure prior to arriving on site that all of your equipment is operational. Your equipment should be configured and ready to survey before your arrival at the customer's site. By doing these two things, you will be ready to get started with the survey when you arrive. • Call ahead and find out if a manlift will be needed to reach the ceiling. If so, find out if the customer will provide the lift or if he expects you to provide the lift. Make sure that you have the proper equipment, and if necessary, a license to operate the lift. • Charge all batteries and battery packs the night before you are scheduled to survey.

• The easiest way to start a site survey is to pick one area of the facility that needs coverage. • Choose a corner and place the AP in the corner. Survey the coverage of that AP and make a note of where the furthest point of coverage is from that AP. • Then move the AP to that point. If you were to place the AP in the corner, as much as 75% of your coverage cell might be wasted covering an area outside the building that does not need coverage. • Once you have moved the AP, then survey the coverage of the AP. • It maybe necessary to move the AP several times in order to find best placement. • Once you have decided on the best location for that AP, then move to a different corner of the facility and repeat the process. In a simple warehouse like the one shown above, you would repeat the process four times. The survey of the RF coverage would then be complete.

• In a more advanced survey, repeating the process four times might only provide coverage around the perimeter of the facility. You would then need to fill in the holes. This is where experience and judgment will come into play. Some engineers might elect to survey the perimeter and then fill in the center. • Remember, if you need seamless coverage, the coverage cells must overlap. • For a standard survey, 15% overlap is usually sufficient to provide for smooth, transparent handoffs. If you intend to use repeaters, then the repeaters will need to have a 50% overlap with a wired AP.

• Another approach is to survey the first two APs and find the coverage areas. Then place an AP at the edge of the first AP's cell, survey the coverage, and then move the AP out further to utilize it's entire cell. This allows you to roughly judge the size of the cell and then move the cell. Survey the new location to determine feasibility and adjust as necessary. • Once the AP location has been decided, the SE would continue this process until the entire facility is covered.

• When you are surveying, take into account the fact that there are only three non-overlapping channels. In order to maximize your data rate, use these channels. By using the non-overlapping channels you insure that the APs will not interfere with each other. • As you design the WLAN, survey using the channel that you intend that AP to operate on. • Part of your survey duty is to test for interference. If you survey every AP using the same channel, and not the actual channel the AP will be using, you cannot be certain that no interference exists on the channel that the AP will actually be using.

• Once you know the minimum data rate your customer will be using, survey at that data rate. • The data rate you choose will drastically effect the results of your site survey. • In the example above, we see the same warehouse surveyed at two different datarates. •If at 2Mb it takes six APs to cover the facility... •At 5.5Mb it might take twelve APs to cover the facility. • Know what your customer needs. If you survey at the wrong data rate and the customer installs the WLAN, he may be able to only connect in certain areas, or unable to connect at all!

• What if there is too much overlap? • The engineer might find himself in a situation where one more AP may provide too much coverage, but the current number of APs provides too little coverage. • At this point the SE has some options. He may elect to use a different antenna to obtain more coverage from the APs. • Or he may elect to use smaller antennas and add more APs. • Still another possibility is changing the power levels on one or more of the APs to change the size of the coverage cell(s). • Or he may elect to use a combination of these options to get the coverage he needs.

• The process is one of trial and error. Again, experience will play a vital role here. • Site surveys can often be like puzzles. And sometimes individuals can become so sure that they know THE solution they fail to see other solutions. • Whenever possible, take the time to talk with other SEs about their surveys. They may have come up with very creative solutions that you can implement in your future designs. • More times than not this conundrum presents itself because the SE has surveyed a few APs only to find out that ultimately his plan will not work. • Instead of wiping the slate clean, an SE may try option after option to force the last piece of the puzzle to fit.

• What if there is too much overlap? • The engineer might find himself in a situation where one more AP may provide too much coverage, but the current number of APs provides too little coverage. • At this point the SE has some options. He may elect to use a different antenna to obtain more coverage from the APs. • Or he may elect to use smaller antennas and add more APs. • Still another possibility is changing the power levels on one or more of the APs to change the size of the coverage cell(s). • Or he may elect to use a combination of these options to get the coverage he needs.

• The process is one of trial and error. Again, experience will play a vital role here. • Site surveys can often be like puzzles. And sometimes individuals can become so sure that they know THE solution they fail to see other solutions. • Whenever possible, take the time to talk with other SEs about their surveys. They may have come up with very creative solutions that you can implement in your future designs. • More times than not this conundrum presents itself because the SE has surveyed a few APs only to find out that ultimately his plan will not work. • Instead of wiping the slate clean, an SE may try option after option to force the last piece of the puzzle to fit.

• Sometimes site survey problems are due to frustration, and sometimes laziness. • An engineer's mind might become "single track" because he doesn't want to start the survey over again. • If you find yourself in this situation it is best to take a break from the work. Go for a cup of coffee, check voicemail, or take a lunch break to let your mind rest. Upon your return you may find that the best solution presents itself. • If not, it may be necessary to wipe the slate clean and start over. You may have found trouble spots that you had not anticipated. • By starting the survey over you will be aware of these trouble spots and can factor in this knowledge when planning the layout of the APs again. • It is always better to start the survey over and design the WLAN properly than to try and force a solution or use a solution that may not provide the best coverage.

• There may be times when the location of the APs may be dictated by available network connectivity. Copper has a length limit of 328 feet, for example. But no matter what the problem, there is almost always a way around it. • Take the warehouse shown above, for example. Network connectivity is only available along one wall. The warehouse is filled with shelving that creates long, narrow aisles. • A good solution for this warehouse may be to locate APs along the wall where they can be connected to the network. Using Yagi antennae you could shoot down the aisles, covering an aisle and a portion of two other aisles. • Overlap the coverage such that the entire warehouse is covered. The signal may bounce off the metal walls at the far end of the warehouse and fill in the dead spots created by the shelving.

• In the example above, we are looking at a distribution center. The DC stores perishable items. Different areas of the DC are kept at different temperatures. Some of the areas are freezers with temperatures as low as -20°. • Installing APs in areas with temperatures this low may require expensive heated enclosures to protect the APs. • An alternative may be to use an antenna splitter. By using a splitter, the AP can be mounted outside the freezer with one antenna providing an area of coverage outside the freezer and the other antenna providing coverage inside the freezer. • Beyond the savings to the customer from not having to buy the expensive heated enclosure, you save him having to pay for the extensive time it would take to install cable and power inside the freezer. Installing this type of equipment while wearing a sub-zero suit and heavy gloves can take a quite a bit of time and be very expensive.

an • Remember that the APs can use antenna diversity. • While using antenna diversity the AP uses one antenna or the other, but never both ! • Do not try an attach one antenna to each connector and place one inside the freezer and the other outside the freezer. This would not be an effective solution. • In the example above, using the antenna splitter, the diversity antenna feature might be disabled. Otherwise, two splitters and four antennae would be needed.

• Special caution needs to be taken when surveying multi-floor facilities. APs on different floors may be able to interfere with each other as easily as APs located on the same floor. • It is possible to use this to your advantage during a survey. Using larger antennae, it may be possible to penetrate floors and ceilings and provide coverage to floors above as well as below the floor where the AP is mounted. • In the example above, a four story office complex needed to be covered. A single AP would not cover an entire floor. Mounting two APs on each floor would be expensive and might present a problem with APs on the same channel overlapping. • The problem was solved by using patch antennae on the APs. Because the patch antenna is semi-directional, there was enough coverage from each AP to cover most of one floor and a portion of the floors above and below it. By mounting APs on alternating floors and at opposite ends of the building, the SE was able to achieve the desired

coverage with only four APs.

• Sometimes there will be areas within a site that cannot be covered. In the example shown here, we are looking at a trauma room in a hospital. The surrounding Emergency room is covered. The Emergency room has drop tile ceilings, sheetrock walls, a tiled linoleum floor, and presents very little challenge. • A patient may be brought into the trauma room and xrays taken there. However, the trauma room has heavy wooden doors, a hard cap ceiling, concrete walls, and a poured concrete floor which are lead-lined to protect the surrounding ER. • In this example, there is no coverage whatsoever in the trauma room. The trauma room is designed to be extremely sterile and the hospital did not want exposed wiring and APs in the trauma room. Because of this, the hospital's application was redesigned to accommodate the occasional disconnect. The application was changed such that during periods of disconnect, the node would store all the data as a batch unit, and then send the data once connectivity was reestablished.

• During your survey you may find that the coverage from an AP is not be what you expect. • You may have surveyed a number of APs already in the facility and have some idea of the average size of an AP's cell. But for some reason, the cell you are currently surveying seems small. • Always try and mount the antennae in an open area for best signal propagation. • Look for objects that may be affecting the RF signal. There are a number of objects that can cause interference.

• Some of the objects that may have a detrimental effect on your signal are: - Cardboard, wood, or paper (which may contain a lot of moisture) - Walls fabricated from "chicken wire" and stucco - Filing cabinets - Firewalls - Metal - Concrete - Transformers - Refrigerators - Heavy-duty motors • Also watch out for sources of Electromagnetic Interference (EMF): - Fluorescent lights (FUSION 2.4 GHz lighting systems) - Microwave ovens - Air conditioning ductwork - Other radio equipment • Always attempt to mount the AP as far away from these items as possible.

• In this section, we have shown you how to get started performing a site survey. We have pointed out some of the areas that may give you trouble and introduced various methods and approaches for surveying different types of facilities • Now it is up to you to work with the equipment and gain the experience you need to become a professional site survey engineer. You will start this process in the next section. • You will be given the opportunity to survey the facility around you. While doing this, remember, there are always going to be others around you, going about their day-to-day business while you are trying to survey. Do your best not to disturb these people while you do your work. This applies here in this facility as well as every other facility you will ever survey.

• From the ACU Menu Bar, choose Commands>Site Survey. You should see the Site Survey Screen. • The current Status is read from the Cisco Wireless LAN Adapter four times per second to quickly gauge the Signal Strength, Beacons, Overall Link Quality, and Associated Access Point. The Site Survey screen includes bar graphs for Signal Strength, Beacons Received, and Link Speed as well as line charts for each to show trends over time. • Besides showing the associated AP and the IP address of the associated AP, the ACU shows the channel the client is using to communicate with associated AP.

• Note that the ACU is in Passive Mode. The ACU has two modes while running a site survey - Passive and Active. • In Passive Mode, the ACU does not initiate any RF Network traffic, it only listens to any other RF network traffic that the Cisco Wireless LAN Adapter hears (from the associated AP). • To set up active mode, press the Setup button at the bottom of the screen. If the Setup button is grayed out, it indicates that the client is using a version of firmware that does not support active mode. Upgrade the firmware.

• After clicking the Setup button, you should see the Site Survey Setup Screen. This screen allows you to customize the site survey parameters. • Destination MAC Address - Specifies the MAC address of the device on which the site survey will be performed. This should be the MAC address of the AP that you will be using during the site survey. • Destination Is Another Cisco/Aironet Device - Check this box if the device you are connecting to is either a Cisco device or an older legacy Aironet device. • Continuous Linktest - Check this box if you want the site survey to run continuously. The survey will run continuously until it is stopped by clicking the Stop or OK button.

• Number of Packets - Number of packets that will be sent during the site survey. This value is adjustable from 1 -999 and may be adjusted using the slider bar or by entering a numeric value in the box. • Packet Size - Adjust the packet size. This value can be set using the slider bar or by entering a numeric value in the box. Packet size should normally match the maximum packet size that will be sent using the WLAN. • Data Retries - The number of times to retry a transmission if an ACK is not received from the destination. • Data Rates - Sets the bit rate at which the packet will be transmitted. No rate shifting will be performed.

• Delay Between Packets - Sets the delay (in milliseconds) between successive transmissions. Set this to a low rate to watch the information scroll across the screen as the site survey is performed. Setting this to a higher value will give you time to examine each packet's transmission. • Packet TX Type - Unicast- expects an ACK back from the destination and retries can occur. Multicast- No packet retries. • Packet Success Threshold - The percentage of packets that are not lost. This parameter controls the red line on the "Percent Successful" histogram. Percentages greater than or equal to this value will show up as green bars, while percentages below this value will show up as yellow bars on the Percent Successful histogram.

• Once you are satisfied with the settings, click the OK button to return to the Site Survey screen. Now click the Start button to start the site survey in active mode. • Percent Complete - shows the percentage of the packets that have been sent. If continuous linktest has been selected, it shows the percentage of packets that have been sent until it reaches 100%, then starts over again. • Percent Successful - shows the number of packets the have been successfully sent and received. Notice the red threshold line. If the percentage drops below this line, the bars will become yellow. • To stop the survey click Stop or OK.

• Click the Status tab. You should see the Status screen. • The status screen on all Cisco Aironet products are very useful screens that provide a substantial amount of information about the device. These screens provide a quick, easy way to find out some of the details about the device. Here we will highlight some of the fields. • Device -This tells you specifically what type of device you are looking at (PC4800, PCM340, etc.) • Firmware Version - Version of firmware currently loaded on the card. • NDIS Driver Version - Version of NDIS driver currently in use.

• Network Type - Indicates if the card is in Infrastructure Mode (connected to an AP), or Ad Hoc Mode (peer-to-peer). • Associated Access Point - Lists the AP that the card is connected to. • Associated Access Point IP Address - List the IP address of the AP the card is connected to. • Up Time - Shows the length of time that the card has been live in hours, minutes, and seconds.

• Current Signal Strength - Bar graph that represents the strength of the signal received from the AP. • Current Beacons Received - Bar graph that represents the percentage of the beacons successfully received from the AP. • Overall Link Quality - Representation of the link quality between the card and the AP, based upon the signal quality and the beacons received. Possible representations are Excellent: Both values greater than 75%; Good: Both values greater than 40% but one (or both) less than 75%; Fair: Both values greater than 20% but one (or both) less than 40%; Poor: One or both values less than 20%.

• From the ACU menu bar choose Commands>Linktest. You should see the Linktest Screen. • IP Address of Access Point - Set this to match the IP Address of the AP you are using to perform a linktest. For a site survey, this will be the AP that you are using for the survey. An IP address must be specified in order to perform a linktest. • Number of Packets - Total number of packets to be sent during the linktest. This setting can be adjusted by moving the slider bar or by entering a numeric value in the box.

• Packet Size – Size of packets to be used during the linktest. This should match the maximum size packets the customer will be trying to send via the WLAN. We will discuss this further in later sections. This setting can be adjusted by moving the slider bar or by entering a numeric value in the box. Be aware that the TCP/IP stack that comes with Windows 95 will fragment packets into 512 byte frames, so specifying a packet size greater than 512 bytes will cause the linktest packets to be fragmented. • Continuous Linktest – Checking this box will allow you to run a continuous linktest. The ACU will ignore the number of packets specified, but not the size. During most site surveys, this box will be checked.

• Click the Start button to start the linktest. More information will be shown on the screen as the ACU starts the linktest. • Statistics for both the current and cumulative number of packets will be shown. These statistics are shown for both Transmit and Receive. These values are periodically updated as the linktest runs. • Also shown is the status of the client (Associated/Not Associated) and, if applicable, the AP Name and MAC Address.