光纤通信课程设计课件Class5-03.pptx

《光纤通信课程设计课件Class5-03.pptx》由会员分享，可在线阅读，更多相关《光纤通信课程设计课件Class5-03.pptx（52页珍藏版）》请在淘文阁 - 分享文档赚钱的网站上搜索。

1、Class 5Class 5Motivation and BackgroundFTTx approachesPoint-to-pointAONTDM-PON(BPON,EPON,GPON)WDM-PONExerciseFTTx=Fiber-to-the-xFTTH-HomeFTTC-CurbFTTN-Node or NeighborhoodFTTP-PremiseFTTB-Building or BusinessFTTU-UserFTTZ-ZoneFTTO-OfficeFTTD-Deskmany types of PONs have been defined APONATM PON BPONB

2、roadband PON GPONGigabit PON EPONEthernet PON GEPONGigabit Ethernet PON CPONCDMA PON WPONWDM PONin this course we will focus on GPON and EPON(including GEPON)with a touch of BPON thrown in for the flavorPON Technologies:OCDMAOCDMA(Optical Code Division Multiple Access)Data Data sourcesourceData Data

3、 recoveryrecoveryC1-Spread spectrum Spread spectrum-Frequency hopping Frequency hopping-OOC(Optical Orthogonal Coding)OOC(Optical Orthogonal Coding)-OBI OBI CiCnC1CiCnOpt encOpt decG.984.5 publishedG.984.1,G.984.3G.984.4 Rev2 publishedG.984.2 amd2,G.984.6 publishedGPON Specs focused&enhanced:3Q07-1Q

4、08x-PON Technology Time Line19952000FSANfounded98990204050601BPON(ITU G.983.1)publishedBPON OMCI(G.983.2)publishedIEEEEPONbeginsFSAN begins GPON03BPON OMCI(G.983.2)RevisedGPON OMCI(G.984.4)publishedGPON TC(G.984.3)publishedIEEE 802.3ah(EPON)published1st GPON Interop EventFSAN begins NG-PONFSAN GPON

5、CTSBPON Completed:April 2000BPON 1st Interop Event:March 2004 BPON 1st wide-scale deployment:May 2004GPON Completed:June 2004GPON 1st Interop Event:Jan 2006GPON 1st wide-scale deployment:4Q 200707IEEE begins 10GEPON087th GPON Interop Event09TDM PON ExampleDownstream TDM transmission with multiple“li

6、steners”(encryption to insure privacy)Upstream TDMA transmission with upstream transmissions(bursts)scheduled to prevent overlapPONs are(in some sense)like HFC systems shared mediumDownstream(single-fiber systems):1490 nm Upstream:1310 nm RF video(if present)1555 nm TDM Time Division Multiplex TDMA

7、Time Division Multiple Access CC Cross Connect NB Narrow Band BB Broadband OLT Optical Line Termination ONT Optical Network Termination TDM ONT2 ONT321:32 Optical splitter(or 1:64 for shorter reaches or with Reach Extender)OLT Access Node NB BB CC Video Data E1/T1/Telephony Data E1/DS1 GbE STMn/OCn

8、ONT1 E1/DS1/Telephony POTSVOIP(and/or)TDMAUp to 60 km*physical reach(*with G.984.6 Reach Extender)Example of WDM-PONAccess nodeOLTSNIwavelength splitter 1 to N ls on single fiberWavelength selection herededicated l1 pairdedicated l2 pairONTBitrate 1ONTBitrate 2Feeder FiberColorless ONTs:Transmitter

9、and Receiver front-end filter characteristics are wavelength adaptableFixed*or adaptable opticspower splitterTDMAONT(Fixed Optics)TDMAONT(Fixed Optics)power splitterHybrid WDM-PON example*“Fixed”optics might be a cost reduced version of convention DWDM long-haul optics NOTE:Most believe adaptable op

10、tics will be required for a practical WDM-PON systemNew Features/Functions:Enhancement Band G.984.5 Wavelength Plan1260128013001320134013601380140014201460148015001520154015601580160016201640166014401680O-bandE-bandS-bandC-bandL-bandU-bandG.984.2Legend:GPON UpGPON DnRF OverlayPresentFuture*Requires

11、the use of reduce water peak fiber(G.652.C/D)*the upper-limit value is determined as an operator choice from 1580 to 1625 nm G.984.5ororNG-PONRegular(FP)Reduce(DFB)Narrow(CWDM)NG-PON(G.9xx)ABNG-PON Option 1*CNG-PON Option 2*DTDM PON Architecture and TechnologiesOLTFiberBPONGPONMax 32 way split(may b

12、e cascaded)OLT implementations may not necessarily support all PON technologies indicatedTypically:622 Mbps/155 Mbps(down/up)ATM-based transportLU#1LU#N,N 32FiberMax 64 way split constrained by PMD attenuation limitsTypically:2488/1244 MbpsGFP-like transports(Ethernet,and/or TDM)LU#1LU#N,N 64EPONFib

13、er1250 Mbps/1250 Mbps 850 Mbps effective payload rate)Ethernet-based transportLU#1LU#N,N 3220 km Maximum Reach20 km ONU differential rangeB-PONG-PONE-PONMax 32 way split(16-way specified in standard)splittersplittersplitterITU-T G.983.xITU-T G.984.x1000BASE-PX20 per IEEE 802.3ahNetwork optical trans

14、ceiver(TXR)shared by“N”subscribersTXRTXRTXRLU#N,N 32ONTONTONTTypical PON Configuration and Optical PacketsTypical PON Configuration and Optical PacketsEye diagram of ONU transceiver Eye diagram of ONU transceiver in burst mode operationin burst mode operationBurst-Mode Transmitter in ONUBurst-Mode T

15、ransmitter in ONUOLT Burst-Mode ReceiverOLT Burst-Mode Receiver Burst-Mode CDRBurst-Mode CDRIdeal,error-free transmissionSuperimposed interferenceHysteresisIdeal sampling instantSamplingSamplingTransceiver Block DiagramTransceiver Block DiagramOptical SplittersOptical SplittersOptical Protection Swi

16、tchOptical Protection SwitchOptical SplitterOptical SplitterLB =PS -PO LB =Link BudgetPS =SensitivityPO=Output Power Example:GPON 1310nm Power:0dbm Single-mode fiberSensitivity:-23dbmLink Budget:23dbBudget Calculations Budget Calculations Assume:Optical loss=0.35 db/kmConnector Loss=2dBSplitter Inse

17、rtion Loss 1X32=17dBRange Budget:11KmTypical Range CalculationTypical Range Calculation Relationship between transmission distance Relationship between transmission distance and number of splitsand number of splitsPON physical layerl allocations-G.983.1Upstream and downstream directions need about t

18、he same bandwidthUS serves N customers,so it needs N times the BW of each customerbut each customer can only transmit 1/N of the timeIn APON and early BPON work it was decided that 100 nm was neededWhere should these bands be placed for best results?In the second and third windows!Upstream 1260-1360

19、 nm (1310 50)secondwindowDownstream 1480-1580 nm(1530 50)thirdwindow1200 nm1300 nm1400 nm1500 nm1600 nmUSDSl allocations-G.983.3Afterwards it became clear that there was a need for additional DS bandsPressing needs were broadcast video and dataWhere could these new DS bands be placed?At about the sa

20、me time G.694.2 defined 20 nm CWDM bandsthese were made possible because of new inexpensive hardware(uncooled Distributed Feedback Lasers)One of the CWDM bands was 1490 10 nm same bottom l as the G.983.1 DSSo it was decided to use this band as the G.983.3 DSand leave the US unchanged1270163014901200

21、 nm1300 nm1400 nm1500 nm1600 nmUSDSavailable guard l allocations-finalThe G.983.3 band-plan was incorporated into GPONand via liaison activity into EPON and is now the universally accepted xPON band-planUS 1260-1360 nm(1310 50)DS 1480-1500 nm(1490 10)enhancement bands:video 1550-1560 nm(see ITU-T J.

22、185/J.186)digital 1539-1565 nm1200 nm1300 nm1400 nm1500 nm1600 nmUSDSData rates(for now)PONDS(Mbps)US(Mbps)BPON155.52155.52622.08155.52622.08622.081244.16155.521244.16622.081244.16155.521244.16622.081244.161244.162488.32155.522488.32622.082488.321244.162488.322488.32EPON1250*1250*10GEPON10312.5*1031

23、2.5*only 1G/10G usable due to linecode work in progressAmd 1Amd 2GPONReach and splitsReach and the number of ONUs supported are contradictory design goalsIn addition to physical reach derived from optical budgetthere is logical reach limited by protocol concerns(e.g.ranging protocol)and differential

24、 reach(distance between nearest and farthest ONUs)The number of ONUs supported depends not only on the number of splitsbut also on the addressing schemeBPON called for 20 km and 32-64 ONUsGPON allows 64-128 splits and the reach is usually 20 kmbut there is a low-cost 10 km mode(using Fabry-Perot las

25、er diodes in ONUs)and a long physical reach 60 km mode with 20 km differential reachEPON allows 16-256 splits(originally designed for link budget of 24 dB,but now 30 dB)and has 10 km and 20 km Physical Media Dependent sublayersLine codesBPON and GPON use a simple NRZ linecode(high is 1 and low is 0)

26、An I.432-style scrambling operation is applied to payload(not to PON overhead)Preferable to conventional scrambler because no error propagationeach standard and each direction use different LFSRsLFSR initialized with all onesLFSR sequence is XORed with data before transmissionEPON uses the 802.3z(10

27、00BASE-X)line code-8B/10BEvery 8 data bits are converted into 10 bits before transmissionDC removal and timing recovery ensured by mappingSpecial function codes(e.g.idle,start_of_packet,end_of_packet,etc)However,1000 Mbps is expanded to 1250 Mbps10GbE uses a different linecode-64B/66BFECG984.3 claus

28、e 13 and 802.3-2005 subclause 65.2.3define an optional G.709-style Reed-Solomon codeUse(255,239,8)systematic RS code designed for submarine fiber(G.975)to every 239 data bytes add 16 parity bytes to make 255 byte FEC blockUp to 8 byte errors can be correctedImproves power budget by over 3 dB,allowin

29、g increased reach or additional splitsUse of FEC is negotiated between OLT and ONUSince code is systematic can use in environment where some ONUs do not support FECIn GPON FEC frames are aligned with PON framesIn EPON FEC frames are marked using K-codes(and need 8B10B decode-FEC-8B10B encode)More ph

30、ysical layer problemsNear-far problemOLT needs to know signal strength to set decision thresholdIf large distance between near/far ONUs,then very different attenuationsIf radically different received signal strength cant use a single thresholdEPON:measure received power of ONU at beginning of burstG

31、PON:OLT feedback to ONUs to properly set transmit power Burst laser problemSpontaneous emission noise from nearby ONU lasers causes interference Electrically shut ONU laser off when not transmittingBut lasers have long warm-up timeand ONU lasers must stabilize quickly after being turned onUpStream t

32、iming diagramHow does the ONU US transmission appear to the OLT?grantgrantlaser turn-onlaser turn-offdatalocklaser turn-onlaser turn-offdatalockinter-ONUguardNotes:GPON-ONU reports turn-on and turn-off times to OLT ONU preamble length set by OLTEPON-long lock time as need to Automatic Gain Control a

33、nd Clock/Data Recovery long inter-ONU guard due to AGC-reset Ethernet preamble is part of dataPON User planeHow does it work?ONU stores client data in large buffers(ingress queues)ONU sends a high-speed burst upon receiving a grant/allocation Ranging must be performed for ONU to transmit at the righ

34、t timeDBA-OLT allocates BW according to ONU queue levelsOLT identifies ONU traffic by labelOLT extracts traffic units and passes to networkOLT receives traffic from network and encapsulates into PON framesOLT prefixes with ONU label and broadcastsONU receives all packets and filters according to lab

35、elONU extracts traffic units and passes to clientLabelsIn an ODN there is 1 OLT,but many ONUsONUs must somehow be labeled forOLT to identify the destination ONUONU to identify itself as the sourceEPON assigns a single label Logical Link ID to each ONU(15b)GPON has several levels of labelsONU_ID(1B)(

36、1B)Transmission-CONTainer(AKA Alloc_ID)(12b)(can be 1 T-CONT per ONU)For ATM modeVPIVCIFor GEM modePort_ID(12b)(12b)PONONUONUT-CONTT-CONTPortPortVPVPVCVCVCVCDS GPON formatGPON Transmission Convergence frames are always 125 msec long19440 bytes/frame for 1244.16 rate38880 bytes/frame for 2488.32 rate

37、Each GTC frame consists of Physical Control Block downstream+payloadPCBd contains sync,OAM,DBA info,etc.payload may have ATM and GEM partitions(either one or both)payloadPCBdpayloadPCBdpayloadPCBdGTC framePSync(4B)Ident(4B)PLOAMd(13B)BIP(1B)PLend(4B)PLend(4B)US BW map(N*8B)ATM partitionGEM partitionscrambled125 msecReference:Survivable Network Architectures for WDM PON