Wimax 143

WIMAX BY SHASHI JAKKU

Contents          

Introduction Working of WIMAX IEEE 802.16 standard 802.16 Architecture IEEE 802.16 Specifications Features of WIMAX Advantages of WIMAX over WIFI WIMAX vs. 3G ISSUES in WIMAX vs. 3G FUTURE OF WIMAX

What is WIMAX? 

WIMAX stands for Worldwide Interoperability for Microwave Access



WiMAX refers to broadband wireless networks that are based on the IEEE 802.16 standard, which ensures compatibility and interoperability between broadband wireless access equipment



WiMAX, which will have a range of up to 31 miles, is primarily aimed at making broadband network access widely available without the expense of stringing wires (as in cable-access broadband) or the distance limitations of Digital Subscriber Line.

A WIMAX system consists of 

A WiMAX tower, similar in concept to a cell-phone tower - A single WiMAX tower can provide coverage to a very large area as big as 3,000 square miles (~8,000 square km).



A

WiMAX receiver - The receiver and antenna could be a small box or Personal Computer Memory card, or they could be built into a laptop the way WiFi access is today

WIMAX TOWER

WIMAX RECEIVER

HOW WIMAX works?

WIMAX CHIPS WiMAX Mini-PCI Reference Design

Intel’s first WIMAX chip

802.16 Architecture 

P2MP Architecture BS connected to Public Networks BS serves Subscriber Stations (SS) Provides SS with first mile access to Public Networks



Mesh Architecture Optional architecture for WiMAX

P2MP Architecture

FEATURES OF WIMAX 

Scalability



Quality of Service



Range



Coverage

Scalability 

The 802.16 standard supports flexible radio frequency (RF) channel bandwidths.



The standard supports hundreds or even thousands of users within one RF channel



As the number of subscribers grow the spectrum can be reallocated with process of sectoring.

Quality of Service 

Primary purpose of QoS feature is to define transmission ordering and scheduling on the air interface



These features often need to work in conjunction with mechanisms beyond the air interface in order to provide end to end QoS or to police the behaviour or SS.

Requirements for QoS 







A configuration and registration function to pre configure SS based QoS service flows and traffic parameters A signalling function for dynamically establishing QoS enabled service flows and traffic parameters Utilization of MAC scheduling and QoS traffic parameters for uplink service flows Utilization of QoS traffic parameters for downlink service flows

RANGE  





Optimized for up to 50 Km Designed to handle many users spread out over kilometres Designed to tolerate greater multipath delay spread (signal reflections) up to 10.0μ seconds PHY and MAC designed with multimile range in mind

Coverage 

Standard supports mesh network topology



Optimized for outdoor NLOS performance



Standard supports advanced antenna techniques

BENEFITS OF WIMAX 

Speed 



Wireless  



Faster than broadband service Not having to lay cables reduces cost Easier to extend to suburban and rural areas

Broad Coverage 

Much wider coverage than WiFi hotspots

Benefits to Service Providers 

 



Allow service providers to deliver high throughput broadband based services like VoIP, high-speed Internet and Video Facilitate equipment compatibility Reduce the capital expenditures required for network expansion Provide improved performance and extended range

Benefits to Customers 



 

Range of technology and service level choices from both fixed and wireless broadband operators DSL-like services at DSL prices but with portability Rapidly declining fixed broadband prices No more DSL “installation” fees from incumbent

Why not WIFI      

Scalability Relative Performance Quality of Service Range Coverage Security

Scalability 802.11 •

•

Wide (20MHz) frequency channels

MAC designed to support 10’s of users

802.16a Channel bandwidths can be chosen by operator (e.g. for sectorization) • 1.5 MHz to 20 MHz width channels. MAC designed for scalability. independent of channel bandwidth •

•

MAC designed to support thousands of users.

RELATIVE PERFORMANCE Channel Bandwidth

Maximum Data Rate

Maximum bps/Hz

802.11

20 MHz

54 Mbps

2.7 bps/Hz

802.16a

1.5 – 20 MHz

100 Mbps

5.0 bps/Hz

Quality of Service 802.11 •

•

•

•

Contention-based MAC (CSMA/CA) => no guaranteed QoS Standard cannot currently guarantee latency for Voice, Video Standard does not allow for differentiated levels of service on a per-user basis

802.11e (proposed) QoS is prioritization only

802.16a •

•

•

•

Grant-request MAC

Designed to support Voice and Video from ground up Supports differentiated service levels: e.g. T1 for business customers; best effort for residential. Centrally-enforced QoS

Range 802.11

802.16a

•

Optimized for ~100 meters

•

•

No “near-far” compensation

•

•

•

Designed to handle indoor multipath delay spread of 0.8μ seconds Optimization centers around PHY and MAC layer for 100m range

•

•

Optimized for up to 50 Km Designed to handle many users spread out over kilometers Designed to tolerate greater multi-path delay spread (signal reflections) up to 10.0μ seconds PHY and MAC designed with multimile range in mind

Coverage 802.11 •

Optimized for indoor performance

802.16a •

• •

No mesh topology support within ratified standards •

Optimized for outdoor NLOS performance Standard supports mesh network topology Standard supports advanced antenna techniques

Security 802.11

•

•

Existing standard is WPA + WEP 802.11i in process of addressing security

802.16a

•

Existing standard is PKM - EAP

Advantages of WiMax over 3G 



Using an assortment of proprietary and standards-based technologies, such as OFDM and W-CDMA ,WiMax has a clear advantage over 3G The advantages include   

Higher Throughput Low Cost Lower Latency

Advantages of WiMax over 3G

Advantages of WiMax over 3G 

WiMax spectrum is more economical than 3G. 

The price paid per Hz is as much as 1000 times lower than for 3G spectrum



The low cost is a clear driver for service providers to enter the field of wireless services with WiMax

Advantages of WiMax over 3G 

WiMAX is important for mobile broadband wireless, as it completes 3G by providing higher performance for data with more than 1 Mbps downstream to allow connection of laptops and PDAs



WiMAX technology is the solution for many types of high-bandwidth applications at the same time across long distances and will enable service carriers to converge the all-IPbased network for triple-play services data, voice, and video

Advantages of WiMax over 3G 

WiMAX interoperable solutions enable economies of scale through integration of standard chipsets, making WiMAX Forum Certified products cost-effective at delivering high-capacity broadband services at large coverage distances in Line Of Sight and Non Line Of Sight conditions

USES OF WIMAX

More ……

FUTURE 

WiMax will be deployed in three stages 





In the first phase WiMaX technology (based on IEEE 802.16-2004) provides fixed wireless connections In the second phase WiMaX will be available as a cheap and self-installing Subscriber Terminal (ST), linked to PC and to antenna The third phase enables portability, thus WiMAX (based on IEEE 802.16e) will be integrated into commercial laptops

Promises

ISSUES in 3G vs. WIMAX 

Deployment of the network 



WIMAX deployment is in the planning stages and it might take 3-5 years in providing reasonable coverage in well populated areas WiMax may initially be relegated to college campuses and larger corporate campuses where people are less mobile and costs containment is important

ISSUES in 3G vs. WIMAX 

Quality of Service 

To provide quality of service by deploying WIMAX networks and to facilitate the continuous availability of service, careful planning is required at the edge of the network to manage network monitoring, availability, failover, routing etc



This can actually be done using outsourced services in cheap labor markets like India and China via the public Internet

ISSUES in 3G vs. WIMAX 

Cost Issue 

The main reason to opt for WIMAX is its low cost.



The price paid per Hz for WIMAX spectrum is as much as 1000 times lower than for 3G spectrum



The low cost of WIMAX spectrum compared to 3G is a clear driver for service providers to enter the field of wireless services with WIMAX

The WIMAX Forum 

Founded in April 2001



No Profit organization comprised of wireless access system manufacturers, component suppliers, software developers and carriers



A wireless industry consortium that supports and promotes WiMAX’s commercial usage



Comply with the WiMAX standard and focus on the interoperability



Members include Intel, AT&T, Siemens Mobile, British Telecommunications, etc

Conclusion (The Final Issue) 

Will WIMAX replace 3G? 

Along with the forthcoming standardization, WiMAX has the potential to substitute 3G and become a promising 4G



WiMAX has its distinct identity as either a stand-alone solution for incumbent and competitive fixed network operators or as complementary radio access solution for established 2G and 3G cellular network operators



Fixed-line operators, on the one hand, may consider WiMAX as a viable alternative to add mobility to the service portfolio, leveraging their huge subscriber base, in particular in countries where 3G licensing is delayed or not affordable

References 

www.ewh.ieee.org/r4/chicago/Yu-WiMAX.pdf



http://computer.howstuffworks.com/wimax.htm





www.wimaxforum.org http://standards.ieee.org/catalog/olis/lanman.html

Questions?