cdma2000_1X基础知识

null CDMA 原理 主要内容 主要内容 码分多址的基本原理 码分多址的关键技术 CDMA同GSM的比较 目标目标 不同用户是如何用码区分出来的 三种CDMA码的用途 CDMA逻辑信道的划分 编码，软切换和功率控制null 码分多址的基本原理 码分多址的关键技术 CDMA同GSM的比较 null• N Users / Wideband Channel • C/I is still negative after I.F. filtering but positive after despreading process • Can consider despreading as the last "filtering" stage• 3 Users / Narrowband Channel • C/I is negative prior to I.F. filtering and positive after filtering1231TDMA (3 timeslots shown)30 kHzFrequencyTime• 1 User/ Narrowband Channel • C/I is negative prior to I.F. filtering and positive after filteringFDMA30 kHzFrequencyTimeDS-CDMA1.23 MHzFrequencyTime CDMACDMA基本原理Walsh CodenullIS-95 was an interim standard developed by TIA/EIA. IS-95 defined mobile station and base station compatibility for the first application of CDMA technology in cellular systems. TIA/EIA is an accredited standards development organization through the ANSI TIA/EIA: Telecommunications Industries Association/ Electronics Industries Association ANSI: American National Standards InstituteIS-95接口标准 MSCCBSCPSTNBTSCDMA系统网络结构 CDMA IS-95A+系统结构实例 CDMA IS-95A+系统结构实例 BTSCBSC 开放的网结构Opening Network Architecture CDG IOSCell SiteVoiceControlL InterfaceUNOOMC- RBTSBTSXCIWUMMMSC/VLR CDG IOSIN ApplicationHLRANSI-41 CDMA 物理信道 CDMA 物理信道 Tx: 870--880MHz Rx: 825--835MHzCDMA 首选载波分配CDMA 首选载波分配联通拥有的频率资源联通拥有的频率资源825835845CDMA Tx870880CDMA Rx960 CDMA/AMPSUC CDMASpectrum Allocation GSM Rx915 GSM TxFreq (MHz)CMCC GSM935890909UC GSMUCUC954A BandB BandA BandB BandCMCC894CMCC939CDMA的基本原理：CDMA码CDMA的基本原理：CDMA码PN码 （伪随机噪声序列） 貌似随机，实际上是有规律的周期性二进制序列。在CDMA中用到两个伪随机序列，长码和短码。 Walsh Code 具有正交特性伪随机码 (PN CODE) 的生成伪随机码 (PN CODE) 的生成 010 0 0 1 1 1 0 0 4 0 1 0 2 1 0 1 5 1 1 0 6 1 1 1 7 0 1 1 3 0 0 1 11425673伪随机码 (PN CODE)伪随机码 (PN CODE) 010 0 0 1 1 1 0 0 4 1 1 0 6 1 1 1 7 0 1 1 3 1 0 1 5 0 1 0 2 0 0 1 11467352Walsh码递归公式Walsh码递归公式8阶Walsh码8阶Walsh码W0 0 0 0 0 0 0 0 0 W1 0 1 0 1 0 1 0 1 W2 0 0 1 1 0 0 1 1 W3 0 1 1 0 0 1 1 0 W4 0 0 0 0 1 1 1 1 W5 0 1 0 1 1 0 1 0 W6 0 0 1 1 1 1 0 0 W7 0 1 1 0 1 0 0 1 CDMA Codes CDMA CodesPN short code Length＝215 －1 ＋1＝ 215 ＝32，768 chips Walsh code 64 PN long code Length＝242-1 4.4× 1012 chipsCDMA系统中采用的编码CDMA系统中采用的编码Walsh 码 在CDMA前向逻辑信道中使用,以区分同一小区或扇区 用户CDMA系统中采用的编码CDMA系统中采用的编码 PN 短码 区分不同扇区或小区 伪随机序列 215 = 32,768 unit (period 26.67ms) 用于前向及反向物理信道扩频PN短码偏置PN短码偏置64 chips32,768 chips / 64 = 512 PN offsets......PN chipsCDMA系统中采用的编码CDMA系统中采用的编码长码 用于反向逻辑信道区分不同用户 伪随机序列 242-1 unit 在前向链路上对业务及寻呼信道进行扰码CDMA前向信道结构CDMA前向信道结构 nullCDMA反向信道结构 nullCDMA前向信道结构nullCDMA前向信道结构nullCDMA反向信道结构nullCDMA反向信道结构null Overhead Channels Traffic Channels Carry messaging,Identification and Primarily carry voice and user data timing information traffic Carry some signaling information used to control MS Pilot Sync Forward Forward Traffic Paging Access Reverse Reverse Traffic CDMA基本原理nullPilot Sync Paging Traffic DSS by Walsh 0DSS by Walsh 32DSS by Walsh 1-7DSS by remaining 55 Walsh codes64 logical channels are combined Then quadrature spread using pilot PN codeCDMA基本原理nullSpread by long code (offset)Spread by long code (offset)Access TrafficQuadrature spread using pilot PN code without any offsetCDMA基本原理null 码分多址的基本原理 码分多址的关键技术 CDMA同GSM的比较 null码激励线性预测编码(CELP) 功率控制 软切换CDMA关键技术CELPCELPCode Excited Linear Predictive Compressed digital voice between XC and MS Uses much less data to approximate the original signal 8K or 13K 功率控制功率控制反向开环功率控制 反向闭环功率控制 前向闭环功率控制null功率控制的重要性nullForwardReverse远近效应功率控制Based on: power measurement (Eb/No) frame error rate(FER)nullTimeAccess ProbesInitial PowerInitial Power+open loop correctionTx Power(dbm)开环功率控制开环功率控制：开环功率控制：Assumes Loss is Similar on Forward and Reverse Paths Receive Power+Transmit Power = -73 All powers in dBm Example: For a Received Power of -85 dBm Transmit Power = (-73) - (-85) Transmit Power = +12 dBm Provides an Estimate of Reverse TX Power for Given Propagation Conditions反向功率控制： 反向功率控制： Maximum System Capacity is Achieved if: All Mobiles are Powered Controlled to the Minimum Power for Acceptable Signal Quality As a result, all Mobiles are Received at About Equal Power at the Base Station Independent of Their Location There are Two Types of Reverse Control: Open Loop Power Control Closed Loop Power Control Open & Closed Loop Power Control are Always Both Active 闭环功率控制：闭环功率控制：Directed by Base Station Updated Every 1.25 msec Commands Mobile to Change TX Power in +/-1 dB Step Size Fine Tunes Open Loop Power Estimate Power Control Bits are "Punctured" over the Encoded Voice Data Puncture Period is two 19.2 kbps Symbol Periods = 103.6 usec nullFDMA & TDMA 切换Break-before-makenullCDMA软切换Make-before-breakCDMA软切换CDMA软切换更软切换 软切换 CBSC 间软切换nullNarrow BandCells CompeteMobile PositionCell ACell BSoft HandoffSignal StrengthABCDMACells Team upBreak Before MakeMake Before Break 软切换null软切换导频集ActiveActiveActiveNeighborNeighborNeighborNeighborNeighborNeighborNeighborRemainingRemaining 有效导频集 相邻导频集 剩余导频集 候选导频集null软切换Threshold & Timer T-Add T-Comp T-Drop T-Tdrop Search, compare, combine, then Soft handoffnull软切换参数Pilot StrengthT-CompT-AddT-dropT-TdropTimeActive PilotNeighbor or RemainingNeighborActiveCandidate分集技术：分集技术：信号元素合并(Rake 接收机) 帧选择nullRake接收机Path Diversity Improves Voice QualityPath Diversity Improves Voice QualityReceiverReceiverReceiverMobile Rake ReceiverAnalog TDMA Calls FadingD/AAudio FadingD/A Mobile ReceiverCDMA CallsEffects of fading are mitigated through use of multiple receivers that sum radio signals from different cells and from reflected rays. Soft Handoff Improves Voice QualitySoft Handoff Improves Voice QualityFrequency Diversity Improves Voice QualityFrequency Diversity Improves Voice QualityOutgoing Waveform 1.25 Mhz1.25 MhzThis 400 Khz fade of 12 db only affects 1/3 of CDMA bandwidth. Therefore, total fade to CDMA user is 2 dbThe entire 30 KHz Channel of TDMA is affected by this same fade. Therefore, total fade to end user is 12 db.CDMA Offers More Protection Against Frequency Selective Fading30 KhzOutgoing Waveform-80 db-90 db-110 db-120 db30 KhzReceived Waveform12 dB Fade2 dB Loss12 dB Fade12 dB Loss!CDMATDMAnull 码分多址的基本原理 码分多址的关键技术 CDMA同GSM的比较 nullCDMA 10 MHz 8个CDMA载波 每载波、每扇区20个话音信道 每小区3个扇区 频率复用系数=1 支持有效话音信道数=8 * 20 * 3 = 480CDMA和GSM技术的比较：CDMA与GSM的小区容量对比：GSM 10 MHz 50个GSM载波(10MHz/200KHz) 每载波8个时隙(包括控制信道和业务信道) 每小区3个扇区 频率复用系数(通常)=4 可配置的站型为S444 支持有效话音信道数 =48 * 8 * /4 = 96-------------->87去除BCCH在相同频谱利用度的情况下，CDMA的容量是GSM的5.5倍nullCDMA 小区覆盖随负载的变化而变化 在无负载的情况下，小区半径是标准GSM的3倍 在每扇区20信道的负载条件下，半径是标准GSM的2倍 GSM 小区在加载的情况下，覆盖保持不变 与GSM相比：在反向链路预算上，CDMA比GSM高5dB反向链路预算比较在相同覆盖条件下， 基站数量减少nullCDMA： N=1 频率复用GSM： N=4 频率复用 2 3 4 4 43 2 4 3 CELL 1 CELL 1 CELL 1 2 频率规划工程：GSM 频率规划 CDMA PN Offset 规划null减少由于切换产生的掉话CDMA 小区/扇区切换采用软/更软切换 切换是先接续再中断 服务质量高，有效减低掉话Cell Site AH A N D O F FCell Site BMAKEAMPS GSMB R E A KCell Site ACell Site BCell Site ACell Site BCDMA中断减低掉话，提高服务质量其它无线系统 小区/扇区切换采用硬切换 切换是先中断再接续 容易产生掉话 nullCDMA特点：技术特点技术特点nullCdma2000 1X 技术特点 cdma2000 1X 网络结构 nullcdma20001X 技术特点Performance EnhancementsPerformance EnhancementsReverse Link Pilot for Each Mobile True QPSK Modulation Continuous Reverse Link Waveform Improved Convolutional Encoding for 14.4 kbps Voice Channels Fast Forward & Reverse Link Power Control Supports Auxiliary Pilots for Beam Forming Forward Link Transmit Diversity - OTD, Multi-Antennacdma 2000 Reuse of TIA/EIA-95-BReuse of TIA/EIA-95-Bcdma2000 is Fully Backwards Compatible with TIA/EIA-95-B Reused Aspects of TIA/EIA-95-B: TIA/EIA-95-B Radio Interface IS-707 Data Services IS-127 EVRC 8 kbps Vocoder and IS-733 13 kbps Vocoder IS-637 SMS & IS-683 Over the Air Activation IS-98 and IS-97 Minimum Performance Standards Common Broadcast Channels (Pilot, Sync Paging) Allows cdma2000 to be Deployed Soonercdma2000 Terms & Definitionscdma2000 Terms & DefinitionsChip A chip is a data bit at the final spreading rate SR - Spreading Rate Defines the final spreading rate in terms of 1.2288 Mcps. So a 3.6864 Mcps system is called a SR3 system. RC - Radio Configuration Defines the physical channel configuration based upon a base channel data rate. RCs contain rates derived from their base rate. For example, RC3 is based on 9.6 kbps and includes 1.5, 2.7, 4.8, 9.6, 19.2, 38.4, 76.8, 153.6, and 307.200 kbps. RCs are coupled to specific Spreading Ratescdma2000 SR1cdma2000 SR1Is an Improved TIA/EIA-95-B Narrowband System Occupies the Same 1.23 MHz Bandwidth as TIA/EIA-95-B Forward Link: Adds Fast Power Control Uses QPSK Modulation Rather than Dual BPSK to: Use 3/8 Rate Convolutional Encoder instead of 3/4 for 14.4 Service (improves error correction) 128 Walsh Codes to Handle More Soft Handoffs for 9.6 service Reverse Link: Uses Pilot Aided BPSK to Allow Coherent Demodulation Uses 1/4 Rate Convolutional Encode Instead of 1/2 or 1/3 Uses HPSK Spreading Enhance System Capacitynullcdma2000 1X 要点技术改善 对数据应用支持 MAC, QoS, 和turbo码 快速前后向功率控制 反向信道相干解调 后向兼容 IS-95A/B Operator Benefits 可支持高达153.6k bps数据速率 与IS-95A/B相比，数据应用能力有4-6倍的提高 与IS-95A/B相比， 话音容量有1.5-1.8倍的提高，减小了运营成本 在保护IS-95A/B投资的前提下，提供了经济有效的过渡策略nullCDMA2000 1x 原理 可变长度的 Walsh Code 码nullWalsh Code Length v.s Data RateEncoder Rate = rInterleaverRepetition Factor = R+A(t)Walsh code (Length WL) at 1.2288mcpsData RateCoded SymbolsRepeated SymbolsModulation SymbolsA(t)=[d(t)/r]*R*WLWL=[1228800*r]/d(t)/RnullW08 0 0 0 0 0 0 0 0 W18 0 1 0 1 0 1 0 1 W28 0 0 1 1 0 0 1 1 W38 0 1 1 0 0 1 1 0 W48 0 0 0 0 1 1 1 1 W58 0 1 0 1 1 0 1 0 W68 0 0 1 1 1 1 0 0 W78 0 1 1 0 1 0 0 1Walsh Code:Generation & Use in 95A/BnullWalsh Code:Generation & Use in CDMA2000W01 =0W02 =00W12 =01W04 =0000W24 =0011W14 =0101W34 =0110W08 =00000000W48 =00001111W28 =00110011W68 =00111100W18 =01010101W58 =01011010W38 =01100110W78 =01101001( W016 ,W816)( W416 ,W1216 )( W216 ,W1416 )( W616 ,W1416 )( W116 ,W916 )( W516 ,W1316 )( W316 ,W1116 )( W716 ,W1516 )SF=1SF=2SF=4SF=8SF=16Effects of Using Variable Length Walsh Codes for SpreadingEffects of Using Variable Length Walsh Codes for SpreadingUsing Shorter Walsh Codes Precludes Using all Longer Codes Derived from the Original Shorter Codes on a Branch map into Longer CodesSF=16SF=2SF=4SF=81 1 1 1 1 1 1 11 1 1 1 -1 -1 -1 -11 1 -1 -11 1 1 11 1 1 -1 1 -1 1 -11 -1 -1 11 1 -1 1 -1 1 -1 1 -11 -1 1 -1 -1 1 -1 11 -1 -1 1 1 -1 -1 11 -1 -1 1 -1 1 1 -11 1 -1 -1 -1 -1 1 11 1 -1 -1 1 1 -1 -11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 -1 -1 -1 -1 -1 -1 -1 -11 1 1 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -11 1 1 1 -1 -1 -1 -1 -1 -1 -1 -1 1 1 1 11 1 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -11 1 -1 -1 1 1 -1 -1 -1 -1 1 1 -1 -1 1 11 1 -1 -1 -1 -1 1 1 1 1 -1 -1 -1 -1 1 11 1 -1 -1 -1 -1 1 1 -1 -1 1 1 1 1 -1 -11 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -1 1 -11 -1 1 -1 1 -1 1 -1 -1 1 -1 1 -1 1 -1 11 -1 1 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 11 -1 1 -1 -1 1 -1 1 -1 1 -1 1 1 -1 1 -11 -1 -1 1 1 -1 -1 1 1 -1 -1 1 1 -1 -1 11 -1 -1 1 1 -1 -1 1 -1 1 1 -1 -1 1 1 -11 -1 -1 1 -1 1 1 -1 1 -1 -1 1 -1 1 1 -11 -1 -1 1 -1 1 1 -1 -1 1 1 -1 1 -1 -1 1null64481632129600192003840076800153600307200614400Data rate -bps-Walsh Code Length -chips-Walsh Code Length v.s Data RatenullLong Code GeneratorBit Selector (Decimator)MUX and Signal Point Mapping 0 --> +1 1 --> -1PC Channel GainData Channel GainData Channel GainPuncture PC Sym. (optional)Puncture PC Sym. (optional)Walsh CodeYqYiMUX ControlIQds1 (t) Wi (t) ds2 (t) j Wi (t) ds1 (t) ds2 (t) PC Bits 800 bps + or - ValuesComplex Walsh CoveringnullX .PN i(t)X . j .PN q(t)= ds1 (t) Wi (t). PN i(t) = ds1 (t) Wi (t). j .PNq(t) S2Z1Y . j .PN q(t)= ds2 (t) j Wi (t). j .PNq(t) jPNq (t)S3S0S1Y .PN i(t)= ds2 (t) j Wi (t). PN i(t) PNi (t)]S2S0S3S1Complex PN Spreading and MappingReal SumImag Sum ZonullCDMA2000 1x 原理 CDMA2000 1x 前反向信道结构nullFL SR1/3Common AssignmentCommon Power ControlPilotCommon ControlSyncTrafficBroadcastPaging (SR1)Quick PagingF- PilotTransmit Diversity PilotAuxiliary PilotAuxiliary Transmit Diversity Pilot0-1 Dedicated Control0-1 FundamentalPower Control /Reverse Pilot0-7 Supplemental Code RC 1-20-2 Supplemental Code RC 3-9CDMA2000 Forward Link ChannelsnullTx Data Rates (bps)20ms FrameRC1RC2RC3RC4RC51200307200153600768003840019200960048002400Rate Set 1 “derived”F-SCH Walsh Codes vs Data Rates for Radio Configuration 3nullTx Data Rates (bps)20ms FrameRC1RC2RC3RC4RC51200307200153600768003840019200960048002400Rate Set 1 “derived”F-SCH Walsh Codes vs Data Rates for Radio Configuration 4nullRL SR1/3AccessR-TCH RC 1/2Enhanced Access Ch OperationR-Common Control Ch OperationR-TCH Operation RC 3-6R-FCH0-7 R-SCCHR-Pilot ChEnhanced AccessR-Pilot ChR-CCCHR-Pilot Ch0-1 R-DCCH0-1 R-FCH0-2 R-SCHR-Power Control SubChCDMA2000 Reverse Link ChannelsnullMUXPilot (all 0s)PC BitsPC BitsPilot (all 0s)384 chipsAPC BitsPilot (all 0s)Reverse Pilot Channel with Reverse PC subchannelnullReverse Link Frame =20ms=16PCGs01234567891011121314151 PCG PC sub-channel Reverse Pilot CHStructure of Pilot Symbols and Power Control BitsnullR-DCCHI - dataQ - datanullCDMA2000 1x 原理 增强型软切换nullCell ACell BSoft HandoffSignal StrengthABT1T2M1M2nullCDMA2000 1x 原理 CDMA2000 OSI结构nullSignaling ServicesIP PCPUDPPacket Data ApplicationHigh - Speed Circuit Network Layer Services Voice ServicesCircuit Data Application MAC LACLAC ProtocolNull LAC MultiplexingMAC Control StateBest Effort Delivery RLPQoS ControlPhysical LayerLink Layer (OSI 2)Upper Layers (OSI 3-7)Physical Layer (OSI 1)Unique to cdma2000LAC functionLAC functionLength and CRC FieldsEncapsulated LAC-PDULAC-PDU FragmentsSARSARSAR9108FieldsLAC-PDU (Non-encapsulated)Sub-LayersIllustrationnullCDMA Technology EvolutionIS-95AIS-95Bcdma2000 1XVoice Cap=15..5E/sector 100% 8k voice Avg sect throughput=75 Kbps Peak Data Rate=14.4 KbpsVoice Cap=15.5E/sector 100% 8k EVRC voice Avg sect throughput=75 Kbps Peak Data Rate=64 Kbps1xEV-DO 1xEV-DV Voice Cap=23.3E/sector w/TD 100% 8k EVRC voice Avg sect throughput=340 Kbps w/TD Peak Data Rate=614 KbpsNo Voice Avg sect throughput=620 Kbps Peak Data Rate=2.4 MbpsVoice Cap=23.3E/sector w/TD 100% 8k EVRC voice Avg sect throughput=1.2 Mbps w/TD Peak Data Rate=5 Mbpsnullcdma2000 1X 网络结构 nullAAAPDSN1X BTS1X BTS To PSTN HAMSC/HLRTo Packet Data NetworkCBSC/AN cdma2000 1X系统功能框图IPnullcost savings% of system using 1X 中低速数据的部署: 低话务区 (郊县/农村) 中低速数据的要求 (14.4 - 64kbps)优势: 在低话务区经济地支持分组数据 提高业务质量 全面支持分组数据IS-95A/Bcdma2000Cdma2000高速数据的部署: 高话务区 (密集城区) 高速数据的要求 (14.4k – 144k – 307k bps)CDMA 95+ 和1X 共存nullcdma20001X 分组接入网nullMobile Station Mobile ClientVLRVisited AAASS7 NetworkAccess Network PCFR-P InterfaceFAPDSNR-P interface A10/A11 MIP/GREcdma2000 1x的数据网络结构nullPacket Data Serving Node (PDSN): 桥接无线接入网（Radio Access Network）和公众数据网（Packet Data Network） 终结PPP会话 协助分组数据计费 FA功能，支持移动IPnull Authentication, Authorization, Accounting Server (AAA) 鉴权 Authentication of profile information 授权 Authorization of data services 计费 Collects billing information from PDSNnullHome Agent (HA) 维护用户登录信息，重定向分组包到PDSN 利用AAA执行鉴权和认证 作为可选功能, 将数据包通过安全隧道转发到PDSNThank You!Thank You!