CDMA原理及硬件结构.ppt

1、CDMA原理及硬件结构,OUTLINE,一、信道结构 二、呼叫过程 MS初始化状态 MS空闲状态 系统接入状态 MS控制业务信道状态 三、MOTOROLA BSS系统结构,信道结构,Forward CDMA ChannelStructure 1、Pilot Channel,导频不含信息，只是用来搜索Pilot PN offset.,2、Sync Channel,用来完成MS的时钟同步和长码同步。Walsh 32 同步信道1帧=26.67ms,3、Paging Channel,寻呼信道1帧=20ms 寻呼模式： 非时隙寻呼模式：移动台在所有的时间内监视寻呼信道 时隙寻呼模式：移动台仅在配置的寻呼

2、信道时隙中监视寻呼信道。由于移动台没有必须在所有的时间内监视寻呼信道，所以在时隙模式内操作的移动台能够保留电池能量。,Paging Channel 中有关长码掩码(LCM)的消息,41-29 28-24 23-21 20-9 8-0 11000110001101 00000 PCN 000000000000 pilot pn offset,PCN:paging channel number(共三位walsh1-walsh7),在长码掩码中包含有两个未知项，PCN和pilot pn offset。所以在手机接受的寻呼信道信息中知道了PCN和pilot pn offset ，手机即可产生相同的长码

3、掩码。,4、Forward Traffic Channel,语音编码1帧=20ms。（话音功率普密度为20-40ms）,功率控制比特（800bps）在前向业务信道通过打孔方式加入，即把一个话音比特用一个功率控制比特来代替。功率控制比特由BTS的MCC板产生。,前向业务信道的长码掩码结构,41-32 | 31-0 1100011000 | ESN,与反向业务信道的长码掩码结构相同,在IS-95A RATE SET 1:9.6K 4.8K 2.4K 1.2K 数字基带信号的速率与功率成正比 Rate X Eb = Power,Reverse CDMA ChannelStructure,1、ACCE

4、SS CHANNEL,对应每一个前向Paging信道，反向可以有32个Access Channel ,即每个小区最多可以由32*7个Access Channel。 接入信道1帧=20ms 接入信道的传输速率固定在4800bps,2、 Reverse Traffic Channel,所有反向信道所加的短码片直为0，反向信道中加短码的目的只是为了扩频,呼叫过程,Power up,Mobile station initilization state,Mobile station idle state,Mobile station idle handoff operation with NGHBR_C

5、ONFIG equal to 011 or unable to receive paging channel message,Ends use of the traffic channel,Mobile station has fully acquired system timing,Initialization task,System Access State,Mobile station Control on the Traffic channel,Receive an acknowledgment to an access channel transmission other than

6、an origination message or a page response message,Directed to a traffic channel,Receives a paging channel message requiring an acknowledgment or response originates a call or partners registration,移动台初始化状态,Power up or any other state,System determination substate,Pilot channel acquisition substate,S

7、ync channel Acquisition substate,Thinking change substate,Ms idle state,CDMA system select,Acquires pilot channel,Recieves sync channel message,在移动台初始化状态，移动台完成系统选择、导频信道捕获、同步信道捕获、计时变化等工作 移动台从同步信道消息中提取并存储系统的基本参数消息，包括系统标识（SID）、网络标识(NID)、导频PN序列偏置索引、寻呼信道速率等，以及定时信息，包括长码状态值、系统时间、出现闰秒的时间、夏令时指示灯 在计时变化子状态，移动台

8、完成： 1、长码同步 2、时钟同步,Sync Channel Message,移动台空闲子状态,Idle Procedures Paging Channel Monitoring Acknowledgement Procedures Registration = GOTO System Access State Idle Handoff Address Recognition for Other than Page Messages Authentication, Encryption, Privacy,在寻呼信道上发给移动台的总共有6条开销消息 系统参数消息 相邻列表消息 CDMA信道列表信

9、息 扩展的系统参数信息 全球服务该导信息 接入参数信息 以上前五个信息是配置信息，移动台连续地接受在寻呼信道上的这些不同的信息，并且将这些信息放到那些需要更新和加载进入移动台的内存中。,系统参数消息 在系统参数消息中主要包含：登记消息、寻呼模式消息、切换消息和功率控制消息等。 有关登记消息 区域登记：REG_ZONE;TOTAL_ZONE;ZONE_TIMER等 开机登记： POWER_UP_REG 关机登记：POWER_DOWN_REG 参数变化登记：PARAMETER_REG 周期性登记：REG_PRD 距离登记：REG_DIST,接入参数消息 在此消息中包含有系统接入时所需 的参数： I

10、NIT_PWR;NOM_PWR;PWR_STEP; NUM_STEP;ACC_CHAN； PROBE_BKOFF;BKOFF等,系统接入子状态 The MS transmits on the Access Channel using a random access procedure. Many parameters of the random access procedure are supplied by the BS in the Access Parameters Message. Power (EDIT SECTOR MSRPC) IP = -73 - Mean Input Powe

11、r (dBm) + NOM_PWR + INIT_PWR NOM_PWR: Nominal transmit power offset (-8 to +7 dB) INIT_PWR: Initial power offset for access (-16 to +15 dB) PWR_STEP: Power increment (0 to 7 dB) 以上参数由数据库定义，IP的大小影响手机的接入速度。 Number (EDIT SECTOR MACC) NUM_STEP: Number of access probes (1 to 16). MAX_REQ_SEQ: Maximum num

12、ber of access probe sequences for an Access Channel request (1 to 15). MAX_RSP_SEQ: Maximum number of access probe sequences for an Access Channel response (1 to 15).,PAM_SZ:Access Channel Preamble length, less 1,in frames. MAX_CAP_SZ: Maximum Access Channel message capsule size, less 3, in frames.,

13、移动台控制业务信道子状态,Traffic Channel initilization Substate,Waiting for Order Substate,Waiting for Mobile Station Answer Substate,Mobile station terminated call and mobile station receive a Base Station Acknowledgment Order on the Forward Traffic Channel,Enter from system access state,Receive a maintenance

14、order or an alert with information message,MS user answers call,MS originated call and ms receive a Base Station Acknowledgment Order on the Forward Traffic Channel,Receive Release Order,Receive Release Order,Release substate,Conversation substate,Receive maintenance order,MS user initiates disconne

15、ct or ms receive Release Order,Receive Alert with information Message,功率控制及功率参数定义,MCC: Eb/No(Eb/No)set PCB=1 降功率 XC: Fer (Fer)target， (Eb/No)set 减小 Fer (Fer)target， (Eb/No)set 增加,MOTOROLA BSS 系统结构,BSS System System Interconnection Signal Flow,BSS System,MM,MSC,BTS,BTS,BTS,OMCR,UNO,XC,CBSC,MM,MSC Int

16、erworking H/O Arbitration Central BSS FM Channel Allocation Page Distribution BSS Init. 2、系统正常工作时，可telnet 到SP平台上作操作维护和故障诊断。,XC,XC Functions,The Transcoder (XC) provides: Speech transcoding (PCM CELP) Span line interfaces supporting EI, TI and JT1 Span line grooming with subrate multiplexing on BTS c

17、onnections BTS link termination Switching of signaling links - MM and MSC - BTSandMM - XCandMM Optional echo cancellation,协议转换功能,BSAP,BSAP,Physical interface (Toking Ring Fiber and E1 Span line),TCP/IP,LAPD,BSAP,BSAP,LAPD,TCP/IP,MM,FEP,BTS,FEP:完成联路层协议转换TCP/IPLAPD,LAPD:Link Access Protocol D (LAPD) i

18、s the transport software used to insure application data sent and received reliably.,OMCR &UNO,OMC-R The OMC-R provides maintenance and control for 1 to 8 BSSs. Operations and maintenance functions: - Database management BSS configuration database control for the Transcoder and BTS devices - Fault management Monitor and/or filter system events Produce event logs and call detail logs Command line interface for event management - Performance management Usage measurement Performance reports,UNO The UNO provides a Graphical User Interface (GUI) for system maintenance. - Terminals provide mult