信息与通信cdmaX基础知识.pptx

单击以编辑,母版标题样式,单击以编辑母版文本样式,第二级,第三级,第四级,第五级,#,1,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,2,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,3,码分多址的基本原理,码分多址的关键技术,CDMA,同,GSM,的比较,4,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 filtering,1,2,3,1,TDMA,(3,timeslots shown),30,kHz,Frequency,Time,1,User/Narrowband Channel,C/I is negative prior to I.F.filtering and,positive after filtering,FDMA,30,kHz,Frequency,Time,DS-CDMA,1.23,MHz,Frequency,Time,CDMA,CDMA,基本原理,Walsh Code,5,IS-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,:,T,elecommunications,I,ndustries,A,ssociation/,E,lectronics,I,ndustries,A,ssociation,ANSI,:,A,merican,N,ational,S,tandards,I,nstitute,IS-95,接口标准,6,MSC,CBSC,PSTN,BTS,CDMA,系统网络结构,7,BTS,CBSC,CDMA,IS-95,A+系统结构实例,开放的网结构,Opening Network Architecture,CDG IOS,Cell Site,Voice,Control,L,Interface,UNO,OMC-R,BTS,BTS,XC,IWU,MM,MSC/VLR,CDG IOS,PSTN,PSTN,IN,Application,HLR,MSC,SMS,VMS,ANSI-41,8,CDMA,物理信道,Tx:870-880MHz,Rx:825-835MHz,9,CDMA,首选载波分配,System Designator,Preferred Set Channel Numbers,A,283(,Primary),691(Secondary),B,384(,Primary),777(Secondary),10,联通拥有的频率资源,825,835,845,CDMA Tx,870,880,CDMA Rx,960,CDMA/AMPS,UC,CDMA,Spectrum Allocation,GSM Rx,915,GSM Tx,Freq,(MHz),CMCC,GSM,935,890,909,UC,GSM,UC,UC,954,A Band,B Band,A Band,B Band,CMCC,894,CMCC,939,11,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,12,伪随机码,(,PN CODE),的生成,0,1,0,001,1,100,4,010,2,101,5,110,6,111,7,011,3,001,1,1,4,2,5,6,7,3,13,0,1,0,0011,1004,1106,1117,0113,1015,0102,0011,1,4,6,7,3,5,2,伪随机码,(,PN CODE),14,Walsh,码递归公式,15,8,阶,Walsh,码,W,0,0 0 0 0 0 0 0 0,W,1,0 1 0 1 0 1 0 1,W,2,0 0 1 1 0 0 1 1,W,3,0 1 1 0 0 1 1 0,W,4,0 0 0 0 1 1 1 1,W,5,0 1 0 1 1 0 1 0,W,6,0 0 1 1 1 1 0 0,W,7,0 1 1 0 1 0 0 1,16,CDMA Codes,PN short code,Length,2,15,1 1,2,15,32，768 chips,Walsh code,64,PN long code,Length,2,42,-1,4.4 10,12,chips,17,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,18,PN,短码,区分不同扇区或小区,伪随机序列,2,15,=32,768 unit (period 26.67ms),用于前向及反向物理信道扩频,CDMA,系统中采用的编码,19,64,chips,32,768,chips/64=512 PN offsets,.,.,.,PN chips,PN,短码偏置,20,长码,用于反向逻辑信道区分不同用户,伪随机序列,2,42,-1 unit,在前向链路上对业务及寻呼信道进行扰码,CDMA,系统中采用的编码,21,CDMA,前向信道结构,22,CDMA,反向信道结构,23,CDMA,前向信道结构,24,CDMA,前向信道结构,25,CDMA,反向信道结构,26,CDMA,反向信道结构,27,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,SyncForward,Forward Traffic,Paging,AccessReverse Reverse Traffic,CDMA,基本原理,28,Pilot,Sync,Paging,Traffic,DSS by Walsh 0,DSS by Walsh 32,DSS by Walsh 1-7,64,logical,channels,are combined,Then quadrature,spread using pilot,PN code,CDMA,基本原理,29,Spread by long code,(offset),Spread by long code,(offset),Access,Traffic,Quadrature spread using,pilot PN code without,any offset,CDMA,基本原理,30,码分多址的基本原理,码分多址的关键技术,CDMA,同,GSM,的比较,31,码激励线性预测编码,(,CELP),功率控制,软切换,CDMA,关键技术,32,CELP,Code Excited Linear Predictive,Compressed digital voice between XC and MS,Uses much less data to approximate the original signal,8K or 13K,33,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,34,功率控制的重要性,35,Forward,Reverse,远近效应,功率控制,Based on:,power measurement(Eb/No),frame error rate(FER),36,Time,Access Probes,Initial,Power,Initial Power+open loop correction,Tx Power(dbm),开环功率控制,37,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,38,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,39,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,40,FDMA&TDMA,切换,Break-before-make,41,CDMA,软切换,Make-before-break,42,CDMA,软切换,更软切换,软切换,CBSC,间软切换,43,Narrow Band,Cells,Compete,Hard,Hand-Off,Mobile Position,Cell,A,Cell,B,Soft,Handoff,Signal Strength,A,B,CDMA,Cells,Team up,Soft,Hand-Off,Break Before Make,Make Before Break,软切换,44,软切换导频集,Active,Active,Active,Neighbor,Neighbor,Neighbor,Neighbor,Neighbor,Neighbor,Neighbor,Remaining,Remaining,有效导频集,相邻导频集,剩余导频集,候选导频集,45,软切换,Threshold&,Timer,T-Add,T-Comp,T-Drop,T-Tdrop,Search,compare,combine,then Soft handoff,46,软切换参数,Pilot Strength,T-Comp,T-Add,T-drop,T-Tdrop,Time,Active Pilot,Neighbor or,Remaining,Neighbor,Active,Candidate,47,分集技术：,信号元素合并,(,Rake,接收机),帧选择,48,Rake,接收机,49,Path Diversity Improves Voice Quality,Receiver,Receiver,Receiver,Mobile Rake Receiver,Analog,TDMA,Calls,Fading,D/A,Audio,Fading,D/A,Mobile,Receiver,CDMA Calls,Effects of fading are mitigated through use of,multiple receivers that sum radio signals from,different cells and from reflected rays.,Fading is more likely to cause loss of information=,lower speech quality,50,Soft Handoff Improves Voice Quality,Multiple receive paths,Switch,Frame Quality Indicator,Quality,Frames,Frame Quality Indicator,Quality,Frames,Quality,Frames,Improved Speech Quality,Transcoder picks best,frame from up to three soft,handoff cells.,CDMA Soft Handoff Improves Frame Quality,4,3,2,1,4,3,2,1,seven frames shown,in this example,1,2,3,4,5,6,7,1,1,2,2,3,3,4,4,5,5,6,6,7,7,Chosen frames of Transcoder,51,Frequency Diversity Improves Voice Quality,Outgoing Waveform,-80 dB,-90 db,-110 db,-120 db,1.25 Mhz,1.25 Mhz,This 400 Khz fade of 12 db only affects 1/3 of CDMA bandwidth.,Therefore,total fade to CDMA user is 2 db,The 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 Fading,Received Waveform,-80 db,-90 db,-110 db,-120 db,30 Khz,Outgoing Waveform,-80 db,-90 db,-110 db,-120 db,30 Khz,Received Waveform,-80 db,-90 db,-110 db,-120 db,12 dB Fade,2 dB Loss,12 dB Fade,12 dB Loss!,CDMA,TDMA,52,码分多址的基本原理,码分多址的关键技术,CDMA,同,GSM,的比较,53,CDMA 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 =480,CDMA,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(10,MHz/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,54,CDMA,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5,dB,反向链路预算比较,在相同覆盖条件下，,基站数量减少,55,1,1,1,1,1,4,1,1,1,1,1,1,1,1,CDMA：N=1,频率复用,GSM：N=4,频率复用,2,3,4,4,4,3,2,4,3,CELL,1,CELL,1,CELL,1,2,频率规划,工程设计：,GSM,频率规划,CDMA PN Offset,规划,56,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,H,A,N,D,O,F,F,Cell,Site,B,MAKE,AMPS,GSM,B,R,E,A,K,Cell,Site,B,Cell,Site,B,CDMA,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,57,CDMA,特点：,技术,特点,技术特点,58,Cdma2000 1X,技术特点,cdma2000 1X,网络结构,59,cdma20001X,技术特点,60,Performance Enhancements,Reverse 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-Antenna,cdma,2000,61,Reuse of TIA/EIA-95-B,cdma2000 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 Sooner,62,cdma2000 Terms&Definitions,Chip,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 Rates,63,cdma2000 SR1,Is 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 Capacity,64,cdma2000 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153.6,k 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,65,CDMA2000 1x,原理,可变长度的,Walsh Code,码,66,Walsh Code Length v.s Data Rate,Encoder,Rate=r,Interleaver,Repetition,Factor=R,+,A(t),Walsh code(Length W,L,),at 1.2288mcps,Data Rate,Coded Symbols,Repeated Symbols,Modulation Symbols,A(t)=d(t)/r*R*W,L,W,L,=1228800*r/d(t)/R,67,W,0,8,0 0 0 0 0 0 0 0,W,1,8,0 1 0 1 0 1 0 1,W,2,8,0 0 1 1 0 0 1 1,W,3,8,0 1 1 0 0 1 1 0,W,4,8,0 0 0 0 1 1 1 1,W,5,8,0 1 0 1 1 0 1 0,W,6,8,0 0 1 1 1 1 0 0,W,7,8,0 1 1 0 1 0 0 1,Walsh Code:Generation&Use in 95A/B,68,Walsh Code:Generation&Use in CDMA2000,W,0,1,=0,W,0,2,=00,W,1,2,=01,W,0,4,=0000,W,2,4,=0011,W,1,4,=0101,W,3,4,=0110,W,0,8,=00000000,W,4,8,=00001111,W,2,8,=00110011,W,6,8,=00111100,W,1,8,=01010101,W,5,8,=01011010,W,3,8,=01100110,W,7,8,=01101001,(,W,0,16,W,8,16,),(,W,4,16,W,12,16,),(,W,2,16,W,14,16,),(,W,6,16,W,14,16,),(,W,1,16,W,9,16,),(,W,5,16,W,13,16,),(,W,3,16,W,11,16,),(,W,7,16,W,15,16,),SF=1,SF=2,SF=4,SF=8,SF=16,69,Effects of Using Variable Length Walsh Codes for Spreading,SF=16,SF=2,SF=4,SF=8,1 1 1 1 1 1 1 1,1 1 1 1-1-1-1-1,1 1-1-1,1 1 1 1,1 1,1-1,1-1 1-1,1-1-1 1,1,1-1 1-1 1-1 1-1,1-1 1-1-1 1-1 1,1-1-1 1 1-1-1 1,1-1-1 1-1 1 1-1,1 1-1-1-1-1 1 1,1 1-1-1 1 1-1-1,1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1,1 1 1 1 1 1 1 1-1-1-1-1-1-1-1-1,1 1 1 1-1-1-1-1 1 1 1 1-1-1-1-1,1 1 1 1-1-1-1-1-1-1-1-1 1 1 1 1,Using Shorter Walsh Codes Precludes Using all Longer Codes Derived from the Original,Shorter Codes on a Branch map into Longer Codes,1 1-1-1 1 1-1-1 1 1-1-1 1 1-1-1,1 1-1-1 1 1-1-1-1-1 1 1-1-1 1 1,1 1-1-1-1-1 1 1 1 1-1-1-1-1 1 1,1 1-1-1-1-1 1 1-1-1 1 1 1 1-1-1,1-1 1-1 1-1 1-1 1-1 1-1 1-1 1-1,1-1 1-1 1-1 1-1-1 1-1 1-1 1-1 1,1-1 1-1-1 1-1 1 1-1 1-1-1 1-1 1,1-1 1-1-1 1-1 1-1 1-1 1 1-1 1-1,1-1-1 1 1-1-1 1 1-1-1 1 1-1-1 1,1-1-1 1 1-1-1 1-1 1 1-1-1 1 1-1,1-1-1 1-1 1 1-1 1-1-1 1-1 1 1-1,1-1-1 1-1 1 1-1-1 1 1-1 1-1-1 1,70,64,4,8,16,32,1,2,9600,19200,38400,76800,153600,307200,614400,Data rate-bps-,Walsh Code Length-chips-,Walsh Code Length v.s Data Rate,71,Long Code,Generator,Bit,Selector,(Decimator),MUX,and,Signal,Point,Mapping,0-+1,1-1,PC,Channel,Gain,Data,Channel,Gain,Data,Channel,Gain,Puncture,PC Sym.,(optional),Puncture,PC Sym.,(optional),Walsh,Code,Y,q,Y,i,MUX Control,I,Q,A,d,s,(t),d,s1,(t)W,i,(t),d,s2,(t)j W,i,(t),d,s1,(t),d,s2,(t),PC Bits,800 bps,+or-,Values,From Interleaver,Complex Walsh Covering,72,X,Y,Complex PN Code,PN(t)1+j,X.PN,i,(t),PN,i,(t),jPNq(t),X.j.PN q(t),=,d,s1,(t)W,i,(t).PN,i,(t),=,d,s1,(t)W,i,(t).j.PNq(t),Complex PN Code,PN(t)1+j,S2,Z1,Y.j.PN q(t),=,d,s2,(t)j W,i,(t).j.PNq(t),jPNq(t),S3,S0,S1,Y.PN,i,(t),=,d,s2,(t)j W,i,(t).PN,i,(t),PN,i,(t),S2,S0,S3,S1,Complex PN Spreading and Mapping,Real,Sum,Imag,Sum,Zo,73,CDMA2000 1x,原理,CDMA2000 1x,前反向信道结构,74,FL,SR1/3,Common,Assignment,Common,Power Control,Pilot,Common,Control,Sync,Traffic,Broadcast,Paging,(SR1),Quick,Paging,F-Pilot,Transmit,Diversity Pilot,Auxiliary,Pilot,Auxiliary Transmit,Diversity Pilot,0-1,Dedicated,Control,0-1,Fundamental,Power Control,/Reverse Pilot,0-7,Supplemental Code,RC 1-2,0-2,Supplemental Code,RC 3-9,CDMA2000 Forward Link Channels,75,Tx Data Rates(bps),20,ms,Frame,RC1,RC2,RC3,RC4,RC5,1200,307200,153600,76800,38400,19200,9600,4800,2400,Rate Set 1“derived”,Walsh Codes,W,n,256,W,n,04,W,n,08,W,n,16,W,n,32,W,n,64,W,n,128,W,n,128,W,n,128,r=1/2,r=1/2,r=1/2,r=1/4,r=1/4,F-SCH Walsh Codes vs Data Rates for,Radio Configuration 3,76,Tx Data Rates(bps),20,ms,Frame,RC1,RC2,RC3,RC4,RC5,1200,307200,153600,76800,38400,19200,9600,4800,2400,Rate Set 1“derived”,Walsh Codes,W,n,256,W,n,04,W,n,08,W,n,16,W,n,32,W,n,64,W,n,128,W,n,128,W,n,128,r=1/2,r=1/2,r=1/2,r=1/4,r=1/4,F-SCH Walsh Codes vs Data Rates for,Radio Configuration 4,77,RL,SR1/3,Access,R-TCH,RC 1/2,Enhanced Access,Ch Operation,R-Common Control,Ch Operation,R-TCH Operation,RC 3-6,R-FCH,0-7,R-SCCH,R-Pilot Ch,Enhanced Access,R-Pilot Ch,R-CCCH,R-Pilot Ch,0-1,R-DCCH,0-1,R-FCH,0-2,R-SCH,R-Power Control,SubCh,CDMA2000 Reverse Link Channels,78,MUX,Pilot(all 0s),PC Bits,PC Bits,Pilot(all 0s),384,chips,1,PCG=4x384 chips=1536 chips,A,PC Bits,Pilot(all 0s),Reverse Pilot Channel with Reverse,PC subchannel,79,Reverse Link Frame=20ms=16PCGs,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,1,PCG,PC sub-channel,Reverse Pilot CH,Structure of Pilot Symbols and,Power Control Bits,80,+,+,PN,Q,PN,I,+,+,PN,I,PN,Q,Walsh Codes-Variable Length,R-DCCH,A,R-PICH,X,C,Relative,Gain,R-SCH2,Relative,Gain,X,B,I-data,Q-data,X,Sin(2,ft+),BBF,Cos(2,ft+),BBF,X,Walsh Codes-Variable Length,Relative,Gain,X,C,R-FCH,Relative,Gain,X,C,R-SCH1,R-EACH,R-CCCH,81,CDMA2000 1x,原理,增强型软切换,82,Cell,A,Cell,B,Soft,Handoff,Signal Strength,A,B,T1,T2,M1,M2,83,CDMA2000 1x,原理,CDMA2000 OSI,结构,84,Signaling,Services,IP,PPP,TCP,UDP,Packet Data,Application,High-Speed,Circuit Network,Layer Services,Voice,Services,Circuit Data,Application,MAC,LAC,LAC Protocol,Null LAC,Multiplexing,MAC,Control,State,Best Effort Delivery RLP,QoS Control,Physical Layer,Link,Layer(OSI 2,),Upper,Layers(OSI 3-7),Physical,Layer(OSI 1),Unique to cdma2000,85,LAC function,Length and CRC Fields,Encapsulated LAC-PDU,LAC-PDU Fragments,SAR,SAR,SAR,9,10,8,Fields,LAC-PDU(Non-encapsulated),Sub-Layers,Illustration,Message type Fields,Utility,5,ARQ Fields,ARQ,3,Addressing Fields,Addressing,4,Authentication Fields,Authentication,2,SDU BODY Fields+MCSB,Layer 3 SDU,1,Pilot Measurement Report Fields,Utility,6,LAC-PDU Padding Fields,Utility,7,86,CDMA Technology Evolution,IS-95A,IS-95B,cdma2000 1X,Voice Cap=15.5E/sector,100%8k voice,Avg sect throughput=75 Kbps,Peak Data Rate=14.4 Kbps,Voice Cap=15.5E/sector,100%8k EVRC voice,Avg sect through