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
excel标准偏差excel标准偏差函数exl标准差函数国标检验抽样标准表免费下载红头文件格式标准下载
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
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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
设计
领导形象设计圆作业设计ao工艺污水处理厂设计附属工程施工组织设计清扫机器人结构设计
: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
综治信访维稳工作要点综治信访维稳工作要点2018综治平安建设工作要点新学期教学工作要点医院纪检监察工作要点
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 BitsnullR-DCCHI - dataQ - datanullCDMA2000 1x 原理
增强型软切换nullCell
ACell
BSoft
HandoffSignal StrengthABT1T2M1M2nullCDMA2000 1x 原理
CDMA2000 OSI结构nullSignaling
ServicesIP
P
ppt
关于艾滋病ppt课件精益管理ppt下载地图下载ppt可编辑假如ppt教学课件下载triz基础知识ppt
CPUDPPacket 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!