Broadband Access Technologies

K K Singh DGM(DX) ALTTC Ghaziabad

What is Broadband Access ? Any data access rate more than 2Mbps is considered as broadband access. As per the recent broadband policy of Govt. of India, access rate over 256 Kbps will come under category of broadband access.

Why Broadband ? Fast development in information technology field has yielded in applications which are bandwidth hungry. Inclusion of more and more graphics and video content in applications require high speed access to network. Network operators are trying to carry realtime traffic like voice and live video over data infrastructure to facilitate a unified network for all type of traffic.

Where to deploy ? Broadcaster

Service provisioning

Broadcast Network

Internet / Telecom Provider

Pac ket Cor e Netwo rk IP, AT M, MPLS

High speed Core transport Node

Headend LMDS WiMAX MMDS WiFi, GSM GPRS UMT S

Access

User Terminal

POT S I SDN xDSL fibr e HF C FTT H

Broadband Access Options Different Broadband access technologies can deployed by a network operator depending resources, infrastructure and availability technologies 

Wireline Access DSL Technology Cable Modem (DOCSIS) Power line broadband access (BPL)



Optical fiber based solutions Metroethernet, RPR, EPON, Ethernet over SDH



Wireless Broadband Access solutions Bluetooth, WiFi, WiMAX, FSO, LMDS, MMDS, VSAT/DTH

be on of

Digital Subscriber Line (DSL) There are various flavors of DSL access over twisted copper (telephone) line.    

ADSL HDSL VDSL IDSL

Asymmetric DSL (ADSL) Allows simultaneous access to the line by the telephone and the computer In case of power/ADSL failure, data transmission is lost but basic telephone service will be operational Provides  

16-640 kbps upstream 1.5-8 mbps downstream

Can work up to a distance of 2.7 to 5.5 kms depending upon the speed required

ADSL Family Asymmetric Digital Subscriber Line ADSL Family Family

Description

Upstream Rate

Downstream Rate

Maximum range

ADSL

G,992.1 / G.DMT

640 KBps

6-8 Mbps

5.5 Km

ADSL Lite

G.992.2 / G.Lite

384 KBps

2 Mbps

6-7 Km

ADSL2

G.992.3 / G.dmt.bis

1 MBps

12 Mbps

5.7 Km

ADSL2 Lite

G.992.4 / G.lite.bis

ADSL2 +

G.992.5 / ADSL 2 plus

1 MBps

24 Mbps

5.5 Km

ADSL2 RE

G.992.3 Reach Extended

1MBps

12 Mbps

6 Km

ADSL Data Rate - Wire Size – Distance Data Rate

Wire Size

Distance

1.5-2.0 Mbps

0.5 mm

18000 Feet

5.5 Kms

1.5-2.0 Mbps

0.4 mm

15000 Feet

4.6 Kms

6.1 Mbps

0.5 mm

12000 Feet

3.7 Kms

6.1 Mbps

0.4 mm

9000 Feet

2.7 Kms

ADSL Home/Office

Curb

Central Office

ADSL CPE ADSL up to 5.5 Km

Data switch

Splitter Twisted Copper Pair

DSLAM

Splitter SHDSL

T SPLI

Internet

TERS PSTN

Voice Switch

Customer can have down load speed Upto 6 MB (3.5 KM) and upload speed 640 Kbps. Telephone works even in Case of power failure.

NIB-II Broadband DSL Deployment Core Network

SSSS

FE

Core router

•

FE

Broadband GigE RAS

GigE

BB GigE

FE

• •

igE

Tier2 LAN Switch

G KM 40 re x Ma k Fib r Da

FE GE

480 Port DSLAM

Gig E & FE

ADM ADM

Tier1 Layer2 GigE Aggregation Switch

ADM

SDH RING ADM B1

city

FE

ADM

FE

B2 city

From MDF FE

FE 240 Port DSLAM

ADSL terminals ADSL terminals

Content Server

FE

GigE

Max 10/20 KM Dark fiber

NOTE: Items indicated in dotted line boxes are not part of Project 2.2

ADSL

120 Port DSLAM

60 Port DSLAM

ADSL terminals Splitter

48 Port DSLAM

24 Port DSLAM

ADSL terminals

NIB-II Broadband DSL Deployment Ex Side

Telco Switch

MDF

Line Side

Normal Line Normal Line DSL Line Normal Line Normal Line DSL Line

DSL Line Normal Line

POTS

Internet

GE/FE

Line

DSLAM

ADSL Services Present and Future Telco Switch

MDF

POTS only

LEX

DSL + POTS

Internet POTS Splitter

ConventionalDSLAMs MultiService Access DSLAMs/DLC Legacy POTS only

Internet

Data

V 5.2

DSL + POTS

POTS Splitter

Telco Switch

HDSL High bit/data rate DSL Can be viewed as equivalent of PCM stream Offers the same bandwidth both upstream and downstream Can work up to a distance of 3.66 to 4.57 kms depending upon the speed required Can deliver 2048 kbps  

On 2 phone lines, each line carrying 1168 kbps On 3 phone lines, each line carrying 784 kbps

HDSL No provision exists for voice because it uses the voice band HDSL-2 is proposed as next generation HDSL over single phone line 

Requires more aggressive modulation, shorter distance and better phone line

SDSL Symmetric Digital Subscriber Line Rate adaptive version of HDSL Does not support analog calls Works up to 3.7 kms on 0.5 mm dia cable Affordable alternative to dedicated leased lines SHDSL-Symmetric High-bit-rate Digital Subscriber Line is an further improvement over HDSL/SDSL and uses single phone line

VDSL Very-high Data-rate DSL Also known as BDSL Originally named VADSL (A –Asymmetric) but was later extended to support both symmetric & asymmetric Requires one phone line Supports voice & data Works between 0.3-1.37 kms depending on speed

VDSL Upstream data rate of 1.6-2.3 mbps Downstream data rate of 13-52 mbps Data Rate - Wire Size – Distance Downstream

Upstream

Distance

12.96 Mbps

1.6-2.3 mbps

4500 Feet

1.37 Kms

25.82 Mbps

1.6-2.3 mbps

3000 Feet

0.91 Kms

51.84 Mbps

1.6-2.3 mbps

1000 Feet

0.30 Kms

IDSL ISDN DSL-a hybrid DSL/ISDN solution Works over existing ISDN connection Increases ISDN speed from 128 kbps to 144 kbps

xDSL Modulation Two types of modulation techniques are used in xDSL Technologies  

CAP - Carrierless Amplitude and Phase DMT - Discrete Multi-Tone modulation

CAP Modulation Carrierless Amplitude and Phase 





Closely related to QAM (Quadrature Amplitude Modulation) QAM generates a DSSC (Double Sideband Suppressed Carrier) signal constructed from two multi-level PAM (Pulse Amplitude Modulated) signals applied in phase quadrature to one another CAP modulation produces the same form of signal as QAM without requiring in-phase and quadrature components of the carrier to first be generated

DMT Modulation Discrete Multi-Tone modulation 





Evolved from the concept of operating an array of N relatively low-rate transceivers in parallel to achieve an overall high rate on one line The N low-rate information streams are kept separated from one another by sending them over N separate frequency sub-bands or subchannels DMT achieves this sub-channel arraying by utilising the IFFT (Inverse Fast Fourier Transform) and it counterpart, the FFT (Fast Fourier Transform)

ADSL DMT Modulation 256 frequency bands of sub-carriers of 4 KHz bandwidth and spacing of 4.3 KHz. Each sub carrier can support maximum 15 no of bit/sec/Hz. Depending on signal to noise Ratio for that sub carrier a decision is taken How many bits that particular sub carrier can Support. Each carrier can carry 0-15 bits/sec/Hz Carriers 1-6 for voice and guardband Upstream

No of Bits

Voice

Downstream

16 7

15

0

4

25

64 31

255

32

1104

138 139

69 kHz Frequency (KHz) Upstream Pilot Tone

276 kHz Downstream Pilot Tone

ADSL DMT Modulation

dB Voice

Upstream

Downstream

Signal to noise ratio

No of Bits

15 Downstream

0

4 25

138 139

Frequency (KHz)

1104

ADSL2+ DMT Modulation ADSL2+ Doubles the bandwidth used to Carry data

No of Bits

Voice

Upstream

Downstream

ADSL2+ 7

15

31

255

32

512

ADSL2 0

4

0.14MHz Frequency

1.1MHz

2.2MHz

Cable Modem The cable network was designed to deliver TV signals in one direction from the Head-End to the subscribers homes Operators had to upgrade the cable network so that signals could flow in both directions One spectrum is used for the signals that move from the Head-End towards the cable subscriber

Cable Modem Another spectrum of signal frequencies are used for the signals that move from the cable subscriber towards the HeadEnd By replacing existing one way amplifiers with two way amplifiers Cable Operators are able to separate the upstream and downstream signals and amplify each direction separately in the right frequency range

Cable Modem In the downstream direction (from the network to the computer), network speeds can be up to 27 Mbps In the upstream direction (from computer to network), speeds can be up to 10 Mbps. 



most modem (DOCSIS) producers have selected a more optimum speed between 500 Kbps and 10 Mbps many cable operators limit the upstream bandwidth to 128 or 384kbs

What is a Cable Modem

Broadband Wireless Access (BWA) Various Technologies are broadband wireless access        

available

in

Personal Area Network (PAN), IEEE 802.15 Wireless LAN, IEEE 802.11 Metropolital Area Network, WiMAX, IEEE 802.16 Wide Area Network, IEEE 802.20 LMDS, MMDS 3G Cellular Mibile network Free Space Optics (FSO) VSAT and DTH based satellite access

Wireless Personal Area Network Bluetooth, IEEE 802.15 What is Bluetooth ?    





Wireless LAN technology (10 meters) PAN 2.4 Ghz band with 20+ Mbps speed Spread spectrum frequency hopping “Always on “ user transparent cable replacement Combination of circuit switching and packet switching (good for voice and data) 3 Voice channels of 64 Kbps each

Bluetooth  A new short-range wireless technology.

 It’s designed for:  Interconnecting computer and peripherals.  Interconnecting various handhelds.

Wireless LAN/WiFi, IEEE 802.11

WiFi Wireless Ethernet standards 

IEEE 802.11 The Initial release of the standard capable of transmissions of 1 to 2 Mbps and operates in 2.4 GHz band using either frequency hopping spread spectrum (FHSS) or direct sequence spread spectrum (DSSS).



IEEE 802.11a Capable of transmissions upto 54 Mbps and operates in 5 GHz band and uses an orthogonal frequency division multiplexing OFDM encoding scheme .



IEEE 802.11b Capable of transmissions of upto 11 Mbps and operates in 2.4 GHz band and uses only DSSS encoding scheme.



IEEE 802.11g Capable of transmissions upto 20+ Mbps and operates in 2.4 GHz band

WiFi in metro Access Wifi was originally designed to replace wired last mile (Indoor Ethernet). However operators are trying to use Wi-Fi in Metro Access environment (Outdoor Ethernet). Although not designed for outdoor use, operators are deploying two different approaches to use Wi-Fi as Broadband Metro Access.  

Wi-Fi with directional antenna Wi-Fi with a mesh-network topology

Increasing 802.11 Range Using Directional Antennas 802.11 Last Mile Networks Proprietary Solutions Wi-Fi Subscriber Station With High-Gain Antenna

Internet

Ethernet

Wi-Fi Telco core network Or private (fiber) network

Wi-Fi

Internal Access Point with hub

Ethernet

Customer Premise (Home, Business or HOTSPOT)

Wi-Fi Access Point With High-Gain antenna

WiFi as Metro Access Mesh Networking Meshing allows wireless connectivity between access points Proprietary  

Lower implementation cost Fault tolerance

AP to AP Communication is not Standardized and hence are not interoperable, The ratification of 802.11s will standardize the Wi-Fi Mesh-network topology. The 802.11s standard is estimated To be ratified in 2007.

Solutions

WiMAX, IEEE 802.16 Worldwide Interoperability for microwave access (WiMAX) It was designed to develop an air interface based on a common MAC protocol Designed a flexible MAC layer and accompanying physical (PHY) layer for 10-60 GHz and 2-11 GHz It will provide fixed, portable, and eventually mobile wireless broadband connectivity Data rate at the rates up to 75 Mb/s per 20 MHz Carrier

WiMAX 802.16 802.16 Last Mile Networks ul a h ck int a B po X A to iM oint W P

WiMAX Subscriber Station

Internet

POTS

Wi-Fi

WiMAX Access Pt to Multipt.

Internal Access Point with hub

Ethernet

Customer Premise (Home, Business or HOTSPOT)

PSTN

WiMAX Base Station

Telco core network Or private (fiber) network

WiMAX, Last Mile Wireless Video Broadband PSTN

Cellular Mobile Telephony BTS Enterprise Customer

Internet

Cellular backhaul

High Speed Core Network Mobile Broadband User

EnterpriseCustomer /Fixed outdoor

Content &  Application  Providers

BBRAS

Home User / SOHO

WiMAX Applications

3

2 FR ACT IONA L E1 for SM ALL BUS INE SS

BA CKH AU L for HOTSP OT S

RESI DENT IAL & SoH o DSL

E1 L EVE L SE RV ICE EN TE RP RIS E

ALW AYS BES T CO NN ECT ED

BA CKH AUL

1

802.16 802.11

Mul ti-Po int BAC KH AU L

802.11 802.11

Mobile Internet User POTS/Internet Services

4

IEEE 802.16 Standards P802.16a — 2.5, 3.5 GHz licensed bands  Point-to-multipoint BWA system  OFDM and single-carrier system  Near LOS operation and fixed outdoor antenna  Max. Range 50 KMs with typical coverage will be around 15 km with outdoor fixed antenna 802.16-Revd 2004 – 2.5, 3.5 GHz licensed band  Non Line of sight operation, OFDM  5 KMs range with indoor antenna attached with modem providing portability within the house 802.16 b – 5.8 GHz license exempt band  Problem of line of sight operation

IEEE 802.16 Standards 802.16e – 2.5, 3.5 GHz Licensed band  



CPE Native in mobile PC It will offer Mobility within a fixed service area of the service provider at varying speed The standard is expected to be ratified in later part of 2005

802.20 - ? 



Complete mobility with roaming from one network to other network. Work under progress

Other Land Based Fixed Wireless Broadband Several different technologies   

transmission

Free Space Optics Local Multipoint Distribution Service Multichannel Multipoint Distribution Service

Free Space Optics (FSO) FSO is optical, wireless, point-to-point, line-of-sight broadband technology that is an alternative to fiber optic cable systems without expense of fiber  Speed is comparable to fiber optic transmissions Transmits up to 1.25 Gbps at distance of 4 miles (6.4 kilometers) in full-duplex mode  Uses low-powered infrared (IR) beam sent through open air by transceivers  Uses unlicensed higher frequency  Currently FSO uses two different wavelengths, but expect worldwide standard in near future

FSO Transmitter

FSO Applications Variety of FSO applications    

Last mile connection LAN connections Fiber optic backup Backhaul

In next few years, FSO is expected to become major player in wireless world

Local Multipoint Distribution System LMDS (Local System) 

   

Multipoint

Distribution

Broadband wireless technology operating in the 28-GHz and 31-GHz ranges. Now systems are available in 11 GHz range also to increase the coverage area Voice, data and video Data rate in the range of 100s of Mbps Available 2001? Line-of-sight technology

LMDS Applications Central Office

Video PSTN

Content &  Application  Providers

Internet

Backhaul for Hotspots

Data,PSTN Video Access

LMDS Cell Site

Data,PSTN Video Access

LMDS Architecture LMDS network is composed of cells Many differences between LMDS cells and cellular telephone system 



Cellular telephone system has mobile users, while LMDS has fixed users Variety of factors affect size of LMDS cells while cells in telephone system are about same size and are based on RF signal traveling from tower to user

LMDS Hub and Remote Unit 28-31 GHz, 11 GHz PMP and PP systems Multiple Mbps to 100’s of Mbps

LMDS Hub Unit

LMDS Remote Unit

LMDS Access And Modulation LMDS uses two access methods to share frequency  

Time Division Multiple Access (TDMA) Frequency division multiple access (FDMA)

Modulation carriers 

techniques

vary

among

Most use a form of quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM), 4-QAM, 16-QAM or 64QAM

Multichannel Multipoint Distribution System In 1998, FCC allowed MMDS frequency to provide two-way services such as wireless Internet access along with voice and video transmissions Similar to LMDS, MMDS can transmit video, voice, or data signals at 1.5 Mbps downstream and 300 Kbps upstream at distances up to 35 miles

MMDS Layout Mounted MMDS hub uses point-to-multipoint architecture By using lower frequencies, MMDS signals travel longer distances and provide service to cells that are up to 35 miles across Pizza box (13 x 13 inch) directional antennas are mounted at receiving location Cable runs from antenna to MMDS wireless modem  Converts analog signal to digital and may be attached to single computer or LAN

MMDS Pizza Box Antenna

Second Generation MMDS Work is underway for Second Generation MMDS 





Will use Orthogonal Frequency Division Multiplexing (OFDM) Stronger signal will eliminate line-of-sight requirement, increase coverage in cell, and simplify antenna installation Speeds may reach up to 9 Mbps downstream and 2.0 Mbps upstream

Fiber Based Access Technologies Ethernet over Dark fibers Ethernet over Sonet/SDH Ethernet over DWDM Ethernet over RPR Ring Ethernet over Passive Optical networks (EPONS)

Optical Implementations Internet Data Center

Ethernet over RPR

Data Center

Ethernet over SDH/DWDM

Ethernet over Fiber Data Center Internet

Ethernet over Dark Fiber Ethernet in the First Mile over Fiber standards- pt-to-pt (EFMF): 100BASE-LX10

Duplex fiber physical, Distance 10 km on 1310nm laser

100BASE-BX10-D

Single Fiber Bi-Directional 1550nm downstream laser (provider side)

100BASE-BX10-U

Single Fiber Bi-Directional 1310nm upstream laser (customer side)

1000BASE-LX10

Duplex Fiber Extended (10 km) 1310nm long wavelength laser

1000BASE-BX10-D

Single Fiber Bi-Directional 1550nm downstream laser (provider side)

1000BASE-BX10-U

Single Fiber Bi-Directional 1310nm upstream laser (customer side)

Ethernet over SDH

Advantages of Ethernet over SDH Common platform to carry TDM and Ethernet services End to end performance monitoring with guaranteed QoS for both TDM and Data traffic. Full fault management SDH resiliency <50 ms switching time for both data and TDM traffic End to End management, provisioning and billing Long Distance Coverage

SONET/SDH Digital Hierarchy Optical Level

Electrical Level

Line Rate (Mbps)

Payload Rate (Mbps)

Overhead (Mbps)

SDH Equivalent

OC-1

STS-1

51.840

50.112

1.728

-

OC-3

STS-3

155.520

150.336

5.184

STM-1

OC-12

STS-12

622.080

601.344

20.736

STM-4

OC-48

STS-48

2488.320

2405.376

82.944

STM-16

OC-192

STS-192

9953.280

9621.504

331.776

STM-64

OC-768

STS-768

39813.120

38486.016

1327.104

STM-256

Ethernet over SDH (Efficiency) Frame relay cannot scale beyond DS3 (44.736 mbps) ATM cannot scale beyond STM-4 (622.080 mbps) due to SAR speed limitations Ethernet rates are 10 mbps, 100 mbps 1000 mbps (1 gbps) & 10000 mbps (10 gbps)– Scaling is not a problem !! Ethernet over SDH on long haul networks is inefficient (see table below) Ethernet Rates

SONET/SDH

SONET/SDH Rates

Effective Payload

Bandwidth Efficiency

10 mbps

OC-1/STS-1

51.840 mbps

50.112 mbps

~ 20 %

100 mbps

OC-3/STM-1

155.520 mbps

150.336 mbps

~ 67 %

1 gbps

OC-48/STM-16

2448.320 mbps

2405.376 mbps

~ 42 %

10 gbps

OC-192/STM-64

9953.280 mbps

9621.504 mbps

~ 104 %

Optimization of Ethernet over SDH To optimize the transport of Ethernet over SONET/SDH links, two new technologies have been standardized.  

Virtual Concatenation (VCAT) Generic Framing Procedure (GFP)

Virtual Concatenation allows for nonstandard SONET/SDH multiplexing to increase bandwidth efficiency Generic Framing Procedure (GFP) provides encapsulation efficiency and eliminates inter-working Functions if any.

Virtual Concatenation (VCAT) Virtual concatenation is valid for STS-1 rates (51.84 mbps) as well as the lower tributaries (1.544 mbps/2.048 mbps) Virtually concatenated channels may be deployed on the existing SONET/SDH network with a simple endpoint upgrade. All the equipment currently in the center of the network need not be aware of the virtual concatenation.

Virtual Concatenation (VCAT) CPE

CPE

10/100

10/100 GbE GbE 802.1q VLAN tag

SDH Ring (OC-48c/STM-16)

STS-3-7v (155.520 x 7 = 1088.640 mbps)

Gigabit Ethernet (1000 mbps)

802.1q VLAN tag

1 Gbps 7 STM 1 Pipes

Gigabit Ethernet (1000 mbps)

Virtual Concatenation (VCAT) The Virtual SONET pipe size may be :  Multiple of STS-1 (51.84 mbps) for high-order VCAT VCAT rates are designated by STS-m-nv for high-order (e.g. STS-1-2v for 100mbps Fast Ethernet) Note: “nv” indicates a multiple n of the STS-m base rate  Multiple of 1.544 mbps (VT1.5) or 2.048 mbps (VT2) for low-order VCAT VCAT rates for lower order are designated by VTm-nv (e.g. VT-2-5v for 10 mbps Ethernet) Note: “nv” indicates a multiple n of the VT-m base rate

Ethernet over SDH (optimization)

Ethernet Rates

Virtual SONET/SDH SONET pipe Rates

Effective Payload

Bandwidth Efficiency

10 mbps

VT-2-5v

2.048 mbps

1.984 mbps

100 %

100 mbps

STS-1-2v

51.84 mbps

50.112 mbps

99.7 %

1 gbps

STS-3-7v

155.520 mbps

150.336 mbps

95 %

Virtual Concatenation (VCAT) Fas t Ether net (1 00 m bps)

Ro uter -A

Fro m OC- 48c/ ST M- 16

ADM OC- 48c/ STM- 16

DWDM MUX

Fast Et herne t (10 0 mb ps)

Ro uter -C

ADM

OC-4 8c/ST M- 16 Rin g

2xSTS1 pipe

ADM

DWDM MUX

DWDM Ring

DWDM MUX

ADM

Fast E the rne t (1 00 mb ps) Ro uter -B

OC- 48c/ ST M- 16

Differential Delay in VCAT Individual STS-1’s or STS-3c’s sub-channels can take different paths through the SONET network. This can introduce differential delay. Buffering at the far end is required to align the sub- channels and extract the original frames. The receiving end-point is then responsible for reassembling the original byte stream after compensating the differential delay if any

Link Capacity Adjustment Scheme LCAS is also useful for fault tolerance and protection LCAS has the ability to remove failed pipes from the VCG (Virtual Concatenation Group) The VCG ends up operating at a reduced bandwidth, but the VCG still continues to carry data that is error-free. LCAS also can add an additional tributary to the VCG when the demand increases

Generic Framing Procedure (GFP) Frame-mapped Need to know the client protocol  Associate a length to each higher frame  Efficient: eliminate the need for stuffing or for block encoding 8B/10B) 

level byte (e.g.,

Transparent No need to know the client protocol  Less efficient; can transmit signal even when the client is idle 

Generic Framing Procedure GFP payload area

2

2

2

2

0-60

PLI

cHEC

Type

tHEC

GEH

Payload length indicator

Core header error checking

Payload type

GFP Type header extension headers error checking

GFP payload GFP payload

GFP combines frame length indication with CRC  

PLI indicated length of frame, then simply count characters cHEC (CRC-16) protects against errors in count field (single-bit error correction + error detection)

GFP designed to operate over octet-synchronous physical layers (e.g. SONET)  

Frame-mapped mode for variable-length payloads: Ethernet Transparent mode carries fixed-length payload: storage devices

Resilient Packet Ring (RPR) IEEE 802.17

Resilient Packet Ring - IEEE 802.17 A New Ring MAC Protocol (IEEE 802.17) 



Unlike Ethernet over SDH no reservation of resources like (STS-1-5v) etc., Allows Packet Add/Drop & Pass through In Ethernet over SDH streams are added/dropped & pass through

Effective Use of Bandwidth Ring Protection  Fast and reliable layer2 protection Control Access Protocol  Fair access to ring BW using Cisco’s Dynamic Packet Transport (DPT) Protocol

RPR

RPR Both rings are used to transport  

User data (traffic) between nodes Control (topology updates, protection and bandwidth control) messages Control messages flow in the opposite direction of the traffic they represent

RPR has the ability to differentiate between low and high priority packets RPR node has the ability to transmit high priority packets while temporarily holding the lower priority packets in the transit buffer

RPR Inner Ring Control

Inner Ring Data

Outer Ring Data

Outer Ring Control

RPR Protection

FAULT

Ethernet over Passive Optical Networks (EPON)

Ethernet over Passive Optical Networks (EPON) Pt-to-M-Pt Ethernet in the First Mile over Passive Optical Networks (EPON) Pt-to-M-Pt Two interfaces to cover a distance of minimum 10 & 20 kms over 16:1 split ratio are developed by IETF P802.3ah. New standards has also come regarding 32:1 splits. 



1000 BASE-PX 10: PHY for PON >= single SM fiber and >=16:1 split ratio 1000 BASE-PX 20: PHY for PON >= single SM fiber and >=16:1 split ratio

10 km over 20 km over

EFM Fiber Point-to-Multipoint 1000BASE-PX 10 & 1000BASE-PX 20 1 Gbps, 1:16 split ratio 10 km single mode fiber

Business and Residential access over SMF Reach for Ethernet over fiber increased up to 10/20km. 1Gbps – Available bandwidth shared by up to 64 users An Ethernet based alternative for Passive Optical Networks.

Passive Optical Network (PON) Passive Optical Networks (PONs)      

Shares fiber optic strands for a portion of the networks distribution Uses optical splitters to separate and aggregate the signal Power required only at the ends ATM PON – APON Ethernet PON – EPON (Pt to M-Pt) Gigabit Ethernet PON – GPON ( Pt to M-Pt)

Hybrid (Active/PON) 

Uses Active Node (powered) and PON to cover larger distances

Fiber loss in PON •

Fi ber lo ss per km is 0. 25 dB for1550 nm an d 0. 4 dB 1260 - 1360 nm

•

Wh en t he sig nal is s pl it two wa ys, hal f the power goes one way an d h alf g oes the other .

•

So ea ch dire ction get s hal f the power , or t he si gn al is red uced by 10lo g( 0. 5) =3 dB . f

al H

//

//

Ha l

f

PON link budgets Link budget (Maximum loss planned) is 21 dB maximum distance without amplification is about 80 km 



At 1550 nm, fiber exhibits loss of about 0.25 dB/km & at 1310 nm loss is 0.4 db/km 80km x 0.25 db/km = 20 db

Each two-way split results in a loss of nominally ~3.5 dB of level, assume 4 dB worst case. 

Thus, each two-way split costs about 16 km distance for 1550 nm & 10 km for 1310 nm

PON Link Budget Split

Loss dB

Loss Km

1:2

4

16

End to End Range 80-16=64

1:4

8

32

80-32=48

1:8

12

48

80-48=32

1:16

16

64

80-64=16

1:32

20

80

80-80=0

1:64

24

96

80-96=-16

APON, EPON or GPON Usually 10-20 km OLT

// //

//

ONU

Op tical s plitter (Passiv e No de – power is not req ui red ) 1x1 6 ( 1x2 , 1x 8)

OLT : Optical Line Terminal

1x3 2 ( 1x4 , 1x 8)

ONU: Optical Network Unit

Architectures – PON 1550 nm video broadcast (if used) OLT 1490* nm data //

//

//

ONU

1310 nm data

* Data may be transmitted at 1550 nm if not used for video

Architecture – Active Node Up to 70 km

Up to 16 km for 1:16 split //

OLT // //

ONU

// //

Active Node with processing (powered)

//

Architectures – Active Node OLT

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1550 nm broadcast (if used) //

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ONU

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Data, 1310 & 1550 or 1490 nm

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Architecture – Hybrid PON Up to 70 km

Up to 10 km (Min)

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OLT Optical splitter

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ONU

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Active Node (powered)

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// Optical splitter

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Architectures – Hybrid PON Single fiber, 1550 broadcast, 1310,1490 bidirectional data OLT

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// 1550 nm broadcast

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ONU

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Data, 1310 & 1550 or 1490 nm

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Downstream Traffic in EPON 802.3x frame FCS

4

Payload Header

2

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1

ONU 1

3

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3

2

1

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//

//

4

3

2

1

2

4 3

4

2

Maximum 64 ONUs can be configured

ONU 2

4

4

1

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2

1

OLT

3

1

Every ONU receives the original Frame which was sent from OLT

3

2

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1

// ONU 3

ONU filters only the traffic meant for that site with the help of an ID Downstream traffic is normally encrypted to avoid security breach

3

ONU 4

// 4

3

2

1

4

Upstream Traffic in EPON (TDMA) 802.3x frame Header Payload

1

FCS

OLT

1

// 1

2

// ONU 1 ONU 2

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1

2

3

//

4

//

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ONUs share the bandwidth in TDMA Fashion when sending the traffic to OLT (upstream) 3 Sufficient gap ( laser off) is maintained between frames from ONUs to avoid overlapping Upstream traffic from one ONU cannot be seen by other ONUs by the Physics of Splitter/coupler

2

2

3 4

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3

// ONU 3 ONU 4

// 4

4