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CDMA Technology Information

CDMA技术信息


CDMA技术信息

Author: 原著： John Danahy

Translated by: 翻译：Cui Yuguang

Checked by: 校对： Cheng Yan

Change History: REV DATE AUTHOR DESC. OF CHANGE

0 11/08/1999 John Danahy Draft 1 08/22/2002 John Danahy CDMA2000 Update 2 Oct 4/2003 Cui Yuguang Start Translate to Chinese 3 Mar 8-11/2004 Cui Yuguang Complete translation 4 Mar 25/2004 Cheng Yan Start checking 5 Apr 05/2004 Cheng Yan Finish checking 6 Apr 06/2004 Cui Yuguang Final Check, Release

********************************************************* NOTE: It is the responsibility of the user of this document to insure it is the most current information available. This document is created and controlled by the Training Department for training purposes only. *********************************************************


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CDMA技术信息

Contents: 目录 SECTION..................................................................................................................................................................... PAGE

1.0 CDMA Standards History ....................................................................................................................3 2.0 Reverse/Forward Channels ..................................................................................................................3 3.0 Cell Plan .......................................................................................................................................................5

3.1 Omni-directional Cell Sites. ............................................................................................................5 3.2 Sectored Cell Sites.................................................................................................................................6

4.0 AMPS and CDMA coexistence ...........................................................................................................6 5.0 Forward Channels ..................................................................................................................................6

5.1 Pilot Channels.........................................................................................................................................6 5.1.2 Walsh Codes .....................................................................................................................................8

5.2 Synchronization Channel ....................................................................................................................9 5.3 Paging Channel ..................................................................................................................................10 5.4 Traffic Channel ..................................................................................................................................12

5.4.1 Forward Vocoder..........................................................................................................................12 5.4.2 Forward Error Protection.........................................................................................................12 5.4.3 Interleaving .....................................................................................................................................12 5.4.4 Long Code Generation ...............................................................................................................13 5.4.5 Closed Loop Power ......................................................................................................................13 5.4.6 Walsh code spreading .................................................................................................................13 5.4.7 Short Code spreading..................................................................................................................14

6.0 Reverse Channels ...................................................................................................................................14 6.1 Access Channel: .........................................................................................................................................14 6.2 Traffic Channel ..................................................................................................................................15

6.2.1 Reverse Vocoder ...........................................................................................................................15 6.2.2 CDMA Frames...............................................................................................................................16 6.2.3 Reverse Traffic Link ...................................................................................................................19 6.2.4 Open Loop Power .........................................................................................................................19 6.2.5 Rake Receiver.................................................................................................................................19

7.0 HandOffs ...................................................................................................................................................20 7.1 Soft Handoff ........................................................................................................................................20 7.2 Hard Handoff......................................................................................................................................21

8.0 Orthogonal Spreading..........................................................................................................................22 9.0 Differences between IS200 and IS95B ...........................................................................................23


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CDMA技术信息 1.0 CDMA Standards History CDMA标准历史 May 1995 IS95-A was introduced as the dual mode cellular band interim standard for CDMA. 1995年 5月 IS95A 成为 CDMA Cell频段过渡标准。 June 1996 J-STD-008 was introduced as the CDMA PCS band interim standard. 1996年 6月 J-STD-008被引入成为 PCS频段过渡标准。 June 1997 IS95-B standard which combine the other two mentioned above with higher voice data rates, also referenced as TSB74 1997年 IS95-B标准, 也称为 TSB74结合了上述两种标准，同时提供了更高的话音编码速率，。 March 2000 CDMA 2000 introduced as the 3G replaces IS95B as new standard. 2000年 3月推出的 CDMA 2000作为 3G标准，取代了 IS95B成为新的标准。

2.0 Reverse/Forward Channels 反向/前向信道 Reverse Link is from Mobile to Base Station and the forward link is from base station to mobile. 反向链路是从手机到基站，前向链路是从基站到手机。 All communication in the CDMA system takes place over a single 1.25 MHz frequency block. The maximum capacity for a CDMA cell is 42 users but typically about 20 subscribers share the same channel, simultaneously. There are approximately 42 AMPS channels per CDMA channel. CDMA系统所有的通信都是在一个 1.25MHz的频段内发生的。一个 CDMA小区的理论最大容量是 42个用户，但是一般情况下，是 20个用户同时共享同一个信道。在一个 CDMA信道内大约可以容纳 42个 AMPS信道。


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CDMA技术信息

ch. 283 ch. 384 ch. 691 ch. 777

Cellular Band CDMA Channels Cell频段 CDMA信道

ch. 25 ch. 50 ch. 75 ch. 1125 ch. 1150 ch. 1175

BW 1.25 MHz

625 kHz

PCS Band CDMA Channels PCS频段 CDMA信道

Every channel is 50 kHz wide and CDMA channels are in multiples of 25 starting with Ch.25 ending at Ch.1175.

625 kHz

BW 1.25 MHz


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CDMA技术信息 3.0 Cell Plan: 小区规划 In the CDMA network adjacent cells can and do use the same frequencies. Shown in the diagram below. The reason that this is possible is because CDMA is designed to decode signals correctly in the presence of high levels of interference. By reusing the same CDMA channel in each and every sector and cell in the system there is a lot less frequency planning compared to the other protocols. 在 CDMA网络中，相邻的小区可以同频复用，如下图所示。这是因为 CDMA可以在较强干扰情况下正确解调信号而使频率复用成为可能。每个蜂窝小区和扇区使用同一个 CDMA信道，使得 CDMA的频谱规划与其它协议相比相对简单。

1

23

45

6

7

7

6

3

7

1

61

2

4

23

45

5

61

23

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7

Analog & TDMA Cell Structure

CDMA Cell Structure

11

11

1

1

11

1

1

1

1

1

1

1

11

1

1

11

1

1

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Transmission range of any given celll

Transmission range ofany given cell

CDMA03.DRW

3.1 Omni-directional Cell Sites.单向蜂窝基站 In an omni cell a single antenna radiates power though out cell and all users will be put on the same channel. Adjacent cells will also have the same channel but will be separated by a different PN (Pseudorandom Noise) offset or code. Different cells are identified by a time delay in their signals. There are 512 PN OFFSETS.


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CDMA技术信息在单向蜂窝中，一个单独的天线在整个蜂窝内发射功率时，所有的用户都被放在同一个信道内。相邻小区

的信道号虽然一样，但是由于 PN码（伪随机噪声码）或 PN码偏移量不一样，所以不会相互影响。不同的小区通过信号的时间延迟来区分。总共可以有 512个 PN偏移。 3.2 Sectored Cell Sites分扇区蜂窝基站 In a sectored cell the antenna transmits and receives energy in a specific direction. Typically they are sectored as 120° or sectored in three. They use this sectorazation because it increases the capacity of the cell. In the cell each sector will have different PN offset. 在分扇区小区内，天线只在特定的方向上发送和接收的能量。典型的情况是间隔 120° 分成 3个扇区。这样做可以增加小区容量。在小区内，每个扇区的 PN码偏移不同。理论上最多可以有 512个 PN码偏移，所以最多有 512个扇区。 4.0 AMPS and CDMA coexistence: AMPS和 CDMA共存 If CDMA and AMPS cells are coexisting, then there has to be a guard zone of approximately 900 kHz from CDMA channel center frequency on each end. The guard zone ensures that there is no interference to CDMA cells from neighboring AMPS frequencies. 如果 CDMA和 AMPS小区共存，那么必须有一个距离 CDMA信道的中心频率大概 900kHz的保护区。保护区可以避免相邻的 CDMA小区与 AMPS频段互相干扰。

900 kHz 900 kHz

CDMA Channel AMPS ChannelAMPS Channel

5.0 Forward Channels 前向信道 BS->MS There are 4 separate signals that are transmitted by the BS: 基站发送 4个不同的信道： • Pilot Channel (Walsh 0). 导频信道 • Synch Channel (Walsh 32). 同步信道 • Paging Channel (Walsh 1-7). 寻呼信道 • Traffic Channel 业务信道 The first three are transmitted continuously by the BS. The Traffic Channel is only transmitted when a call has been established. 基站始终在前三个信道发送信息。业务信道仅当通话建立起来后才有。 5.1 Pilot Channels 导频信道 The CDMA system has a Pilot Channel, which will be the first channel the mobile will try to tune to when it is first power-up. The Pilot is only used to locate the strongest network this is only present in the forward direction. The system information is provided from another channel called the Synchronization Channel. Remember that all these channels are present in the same 1.25 MHz block which is not frequency divided. The key to understanding is to think about what is going on inside the frequency block, instead of taking them as individual channels. The pilot


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CDMA技术信息 channel is always channelized by Walsh Code 0 Xor'ed with the Short code. Short codes are the same for all base stations but a specific mask will shift the PN code to a unique delay with respect to the system time in each base station, thus a unique code. The Short Code is 215 (32768) Bits long and at 1.2288 Mbps (system clock) takes 26.27 ms before repeating itself. Each base station incorporates a GPS receiver to provide exact system timing information for the cell. 导频信道是手机开机后搜寻的第一个信道，它只在前向信道中有，仅用来寻找信号最强的网络或基站。系

统信息存放在同步信道。注意这里所说的信道都是逻辑信道，存在于同一个不可分割的 1.25MHz的物理信道中。理解这个概念的关键是要把频率看成一个整体，考虑在其内部发生了什么，而不是把它看成独立的

信道。导频信道的信道化总是通过Walsh码 0与短码异或得到。短码对于各个基站是一样的，但是当遇到掩码时, PN码相对每个基站的系统时间会产生时间延迟，因而它是唯一的码。短码是 215（32768）比特长度，在 1.2288Mbps系统时钟下每隔 26.27秒重复一次。每个基站都有 GPS接收机用来为小区提供准确的系统时间。

• Base station uses Walsh code 0. 基站使用Walsh码 0, 64位全 0，进入 I/Q调制器 0,输出也是 0. * All 64 bits are 0. • All data into Walsh modulator is 0. * So all outputs are 0's. • Pilot channel is therefore just the PN offset short code. 导频信道输出的只是短码的 PN位移。 • There are 512 different offsets each offset by 64 chips in time. 共有 512个不同位移，每个位移 64个码片时间。

• While scanning for PN offsets at base station once one is found it easy to find others because of the 64 offset in time. 在寻找基站的 PN偏移的过程中，只要找到其中一个，其余的就很容易找到。因为是固定的 64个码片时间偏移。

• All signal strengths of these offset are stored and strongest one used by phone. 所有偏移的信号强度被测量和储存下来，手机选择最强的信号。

• Once strongest pilot signal is found it aligns itself to that particular short code offset, then applies Walsh code 32 in order to demodulate the Synch. Channel. 一旦最强的导频信道发现后，手机就调谐到对应的特定的短码偏移，然后用Walsh码 32来解调同步信道。


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CDMA技术信息

• ? What is Walsh Codes? 什么是Walsh码？ • We use Walsh code set 64 (see chart below). This Walsh set has 64 unique codes containing 64 bits

each. 我们使用下表所表示的 64个 64位Walsh码。 • On the Forward channels different Walsh codes separate different users. 在前向信道中Walsh码用来区分不同用户。

• The reason we use different Walsh codes is because they are orthogonal to each other. 使用不同的Walsh码的原因是因为Walsh码之间是互相正交的。

* Orthogonal means there is an equal number of matches and mismatches. 正交意味着相匹配和不相匹配的码字数目是一样的。 • What makes them ideal is when transmitted simultaneously the produce minimal interference with each

other. Walsh码作为理想的码是因为在同时传输过程中相互的干扰最小。

Walsh Code Generator

Walsh Modulator

1.2288 Mbps

Dataall 0'sinput

Walsh Code 0

Short Code PN Offset


FIR

FIR Phas

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odul

ator

Q

I

1.2288 Mbps

1.2288 Mbps

Short Code Scambler

FIR: Finite Impulse Filter 有限响应滤波器，基带的数字滤波器。FIR之后是中频部分，中频之后是模

拟滤波器。CDMA功能部分尽量在数字部分完成，因为模拟滤波

器既贵又不容易实现。

射频部分

基带部分 5.1.2 Walsh Codes Walsh码

0 1 2 3

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1111101011001001

1111101011001001

1111101011001001


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CDMA技术信息 20212223

0000010100110110

1111101011001001

0000010100110110

1111101011001001

1111101011001001

0000010100110110

1111101011001001

0000010100110110

0000010100110110

1111101011001001

0000010100110110

1111101011001001

1111101011001001

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1111101011001001

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28293031

0000010100110110

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1111101011001001

0000010100110110

1111101011001001

0000010100110110

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1111101011001001

0000010100110110

1111101011001001

1111101011001001

0000010100110110

1111101011001001

0000010100110110

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32333435

0000010100110110

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0000010100110110

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1111101011001001

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Figure 36 Walsh Code Set 64

5.2 Synchronization Channel 同步信道 Basically the Synch Channel carries all the necessary information that the mobile needs to register with the system.从根本上说，同步信道包含了手机登录到系统之前要注册时所需要的所有必要信息。 The Synch Channel is always channelized by Walsh code 32. 同步信道总是使用Walsh码 32信道化。 Pilot PN offset of base station 包含：基站的导频 PN偏移； System Time: The master start time 系统时间：主系统启动时间。（实际是 GPS时间） Local time offset from system time: 本地时间对系统时间的偏移。 Long Code State: Gives the state of the "Long Code" 320 ms in the future. Takes 41 days to repeat itself. Must know the "Code State" 长码状态：长码在 320ms之后的状态。长码每 41天重复一次，必须知道长码状态。 SID, NID 系统 ID，网络 ID (System ID and Network ID) Paging Channel Data Rate: 0, 9600: 1, 4800 寻呼信道数据速率：0，9600：1，4800； Base stations Protocol or Interim Standard 基站的协议或过渡标准。


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CDMA技术信息

Walsh Modulator

1.2288 Mbps


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1.2288 Mbps

Short Code Scrambler

Synch ChannelMessage Data

System Time

Long Code Status

SID

NID

Paging ChannelData Rate

System InterimStandard

Local Time Offset

1/2 rateConvolutional Encoder

2x SymbolRepetition Interleaver

1.2 kbps 2.4 kbps 4.8 kbps

4.8 kbps

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to the Walsh modulator. 交织后进入Walsh调制器（扩频）使用Walsh码 32来扩频 PN offset. 用带 PN偏移的短码扰码

other protocols. When Mobile demodulates the paging channel and lied on the paging channel it will try and register with the base

解调出寻呼信道并解码出其中所包含的各种信息数据后，就

DMA base station. 寻呼信道是 CDMA基站的核心； ary for operation of CDMA cell site are handled on paging channel.的参数和信令都在寻呼信道中处理；

e mobile with system information such as: 基站提供给手机的系统

ation numbers. 系统和基站标志号； orted. 系统支持的寻呼信道的数量；息；阈值。

information for mobile on how to contact access channels when 手机发起首次呼叫时如何联系接入信道的信息。

number of CDMA frequencies supported by the cell site and also lar area. CDMA信道表列出了本地和邻近基站支持的频率列表.

municate the information needed to get the mobile onto a traffic 登录到业务信道所需信息。

ge sends out the preferred mobile station id types and base station's 统参数信息包含首选的移动台类型和基站的国家及网络号。

e tells the mobile the PN offsets of surrounding base station that 扩展邻道列表信息通知了手机附近可以用来进行软切换的基站


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CDMA技术信息

• Service redirection is available so that the base station can redirect a CDMA mobile to other systems (analog). 服务重定向是否存在，因此基站是否可以重定向 CDMA手机到其它类型系统（比如模拟系统）的信息。

• General page message allows the cell site to page CDMA phones for incoming calls 通用寻呼信息允许当有来电时使基站呼叫 CDMA手机。

Always has a Walsh Code between 1 and 7. Any Walsh Codes not used for paging can be assigned as Traffic Channels. After information is gathered by mobile and is registered on the paging channel it can request to go into a standby mode (sleep mode). Proper term is slotted mode which is programmable by the BS in multiples of 1.28 seconds. When in slotted mode, phone powers down all circuitry in RF section and uses sleep clock to track time intervals. When MS wakes up, it must synchronize system time and check for any paging messages, if their is no activity, phone goes back to slotted mode. This cycle is repeated until paged or caller initiates a call. Propose of slot mode is to save considerable energy in battery and get longer standby times. 寻呼信道总是使用Walsh码 1到 7。寻呼信道未使用的Walsh码还可以分配给业务信道。当手机将信息搜集完毕，登记到寻呼信道后，可以请求进入睡眠模式。正确的称呼是 slotted mode，它可由基站在 1.28秒的整倍数的时间间隔上编程定义。当进入睡眠模式后，手机关闭所有的射频电路，使用睡眠时钟跟踪系统时

钟。当手机结束睡眠状态后，必须首先同步系统时间，然后检查寻呼信息。如果没有类如通话等活动，手

机又回到睡眠模式。这个过程会不断重复，直到被呼叫或者主动发起呼叫。睡眠模式的主要目的是节约能

源，延长待机时间。


Walsh Modulator

1.2288 Mbps

Walsh Code 1-7



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1.2288 Mbps


Paging ChannelMessage Data

System Parameters

AccessParameters

Channel Assignment

Extended SystemParameters

Service Redirection

Pilot's PN Offset

General Page Messages




19.2 kbps

Paging Channel Long Code 1/64

Decimator19.2 kbps

1.2288 Mbps

Long CodeScrambling

• Paging channel message data runs at either 4.8 kbps or 9.6 kbps (1/2 or full rate operation). Normally half rate is used because it produces 3dB of processing gain. 寻呼信道信息数据速率 4.8kbps或9.6kbps (1/2或全速率模式)。通常使用半速率因为它能够产生 3dB处理器增益。

• Convolutional encoded to a rate of 9.6kbps. 卷积编码到 9.6kbps。 • Symbol repetition to 19.2 kbps (redundancy). 符号重复到 19.2kbps。 • Interleaved to combat fading, basically by shuffling the data around so it does not occur continuously. 交织以抗衰落，基本上采用把数据打乱的方式。

• This data is then scrambled against the special long code. 数据用用特定的长码扰码，其中包含： * Derived from a pre-determined bit pattern. 预先定义的比特模式； * Paging channel number. 寻呼信道号码； * Pilot's channel's PN Offset. 导频信道的 PN偏移；

• Then Walsh code modulated or spread at 1.2288 Mbps with Walsh code 1 for the first paging channel or Walsh code 2 for the second and so forth up to Walsh code 7. 用Walsh码调制和扩频到1.2288Mbps，使用Walsh码 1~7对应于第一到第七个寻呼信道。

• Scrambled then with the Short code or PN offset. 使用短码或 PN偏移扰码。


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CDMA技术信息 5.4 Traffic Channel 业务信道 The Traffic Channel is the equivalent to the analog voice channel. The remaining Walsh codes are assigned to the traffic channels as required (Walsh codes 8-31, 33-63). At least 55 Walsh codes are available and the actual number depends on the total interference levels (soft limit rule) of all users in a given cell site. Typically full loading would be around 30 traffic channels. 业务信道就像模拟话音信道。所有其余的Walsh码（Walsh 码 8-31, 33-63）都可以赋予业务信道。所以至少有 55个Walsh码可以使用，而实际的数目取决于所有位于同一小区的用户总的干扰水平(软容量规则)。通常满负荷大概只有 30个业务信道。


Walsh Modulator

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Walsh Code 8-31, 33-63



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19.2 kbps

19.2 kbps

Long Code1/64

Decimator19.2 kbps

1.2288 Mbps

Long CodeScrambling

Vocoder

9600

4800

2400

1200

Rate set 1

Decimator1/24 800 bps

MUX

PowerControl Bit

800 bps

19.2 kbps 19.2 kbps 1.2288 Mbps

Xor

5.4.1 Forward Vocoder: 前向话音编码器 Used to convert analog voice signals to and from a digital format. The vocoder for CDMA is a variable rate with a high degree of data compression. The data rate is based on speech activity, normal telephone speech has about a 40% activity factor. When the user is talking the vocoder rate is at 9600bps and when user is pausing or listening the amount of speech data is reduced. The forward vocoder wants to always keep it's output rate at 9600bps so it just repeats voice bits to fill a frame. To keep the speech in neat little packets, CDMA uses 20ms frames each containing up to 192 bits of information (9600 bps/ 50). Running at full rate, each frame contains a mixed mode bit (indicates if the frame is pure channel data or contains some signaling bits), 171 coded speech bits, 12 bits of CRC(correction bits for frame), 8 encoder tail bits (all 0's in a row to flush the contents of convolutional coder in preparation for processing the next frame). 用来将模拟的话音信号同数字格式互相转化。CDMA的声码器是变速率、高数据压缩率的声码器。数据速率基于话音状态。通常电话语音有 40%的激活因子。当用户讲话时，声码器速率是 9600bps，当用户停顿或听的时候，话音数据较少。前向声码器总是要保持其输出速率在 9600bps，于是它重复话音数据比特来填充帧。为保持话音的很小的简洁帧结构，CDMA使用 20ms帧包含最多 192比特信息(9600bps/50)。当运行在全速率时，每个帧包含一个混合模式比特（指示这个帧是纯信道数据还是包含一些信令比特），171个编码话音比特，12个 CRC校验比特，8个尾比特（一行全零，用来给卷积编码器清零，以便处理下一个帧）。 5.4.2 Forward Error Protection: 前向纠错 For forward error correction CDMA uses a half-rate convolutional encoder. This encoder produces two output bits for every input bit. The result is a redundant digital data at a rate of 19.2 kbps. CDMA使用半速率卷积编码器前向纠错。每输入一个比特，输出两个。结果是带冗余数据速率 19.2kbps。 Ex. HELLO CLASS = HHEELLLLOO CCLLAASSSS 5.4.3 Interleaving:交织


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CDMA技术信息 Interleaving adds protection to the data by rearranging the order in which speech data is transmitted. It is like shuffling a deck of cards where you know the order of the shuffle. The data is put into matrix in rows but read out in columns. This makes it less susceptible to interference and fading. 交织通过重新安排话音数据传输的顺序从而对数据加以保护。就象洗牌的时候你已经知道洗牌的顺序。数

据按照行写入，列读出。使得它不易受到干扰和衰落的影响。 Ex. HHEELLLLOO CCLLAASSSS = HLOLSHLOLSELCASELCAS

HHEE HHEE LLLL LLLL OOCC OOCC LLAA LLAA SSSS SSSS

5.4.4 Long Code Generation:长码生成 The long code is generated using a 42-bit linear feedback shift register. The data pattern that it generates repeats every 41.43 days. CDMA uses the system clock to drive the long code sequence generator. A user specific data (ESN) at 42 bits is AND'ed with the Long Code making it unique. Because we do not want to use the long code to spread the signal bandwidth we decimate down from 1.2288 Mbps to 19.2 kbps. In other words we use every 64th bit which matches the voice data and then provide privacy by exclusive OR'ing together. 长码是通过一个 42位的线性反馈移位寄存器生成的。数据长达 41.43天才重复一次。CDMA使用系统时钟来驱动长码生成器。一个特定的用户相关的 42比特数据(ESN)同长码“与”产生一个独特的序列。因为我们不想用长码来扩展信号带宽，所以我们通过抽取使之从 1.2288 Mbps降到 19.2bps。换句话说，我们抽取每第 64个长码比特使得其速率与话音数据速率匹配，然后通过两者异或操作进行加密保护。 5.4.5 Closed Loop Power: 闭环功率控制 Every mobile user's transmitted output must reach the base station at the same signal level of power, in order not to interfere with each other. In other words one persons’ mobile cannot be shouting when everybody else is whispering. The base station monitors the power received from each mobile and commands the mobile to either raise or lower power by a fixed step of 1 dB. This process is done 800 times per second or every 1.25msec. The mobiles power is constantly increasing or decreasing and will never stay the same. This power control data is added to the data steam by replacing the encoded voice data. This is also called puncturing, since the power control data is written or replacing a voice data bit. The time that this power control bit is punctured in the data steam is controlled by the long code decimated down to 800 bps. Now that we replaced voice bits the receiver views these as holes (missing data), but the mobiles Viterbi decoder can recover this missing voice data. 为了不干扰其它用户，每个移动用户的发送功率必须以同样的信号功率水平到达基站。换句话说，当其他

用户都在低声细语的时候，不允许某一个用户大声喊叫。基站会持续监测收到的来自各个手机的功率，然

后命令手机以固定的 1dB步长增加或降低功率。这个过程每秒 800次或者说是每 1.25毫秒一次。这样手机的发射功率总是在上升或下降的变化中，而不会保持不变。功率控制数据通过替换已编码的话音数据加入

到数据流中。由于功率控制数据插入并取代了话音数据比特，这个过程也叫做“凿孔”。功率控制比特凿

入数据流中的时间是由抽取到 800bps的长码控制。由于我们替换了话音比特，虽然接收机会将此看作是缺口（数据缺失），但是手机的 Viterbi解码器可以恢复这些丢失的话音数据。 5.4.6 Walsh code spreading: Walsh码扩频 The 19.2 kbps data steam is now modified by a Walsh code. By taking one of the Walsh code channels (usually W8 – W63 ), and exclusively OR'ing with the data stream we end up with a uniquely scrambled pattern used to identify each user. The ratio of the voice data steam is exactly 64 so when XOR'ed together with the 64 bit Walsh code we end up with a data rate of 1.2288 Mbps thus spreading the data over the bandwidth.


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CDMA技术信息接下来 19.2kbps的数据流被Walsh码改变。通过使用其余的Walsh码信道(通常是W8-W63)，然后同数据流异或，我们得到了惟一的加扰数据模式可以区分不同用户。话音数据流的速率正好是 64，因此当同 64位Walsh码异或后，我们得到了 1.2288Mbps速率的数据，这样就扩展了数据的频谱。 5.4.7 Short Code spreading: 短码扩频 Next the data is scrambled with the Short code. Remember the Short codes are the same for all base stations but a specific mask will shift the PN code to a unique delay with respect to the system time in each base station, thus a unique code. In other words it is the specific base station identifier thus allowing each base station to reuse all 64 Walsh codes differentiating from adjacent cells using the same frequency. 接下来数据用短码扰码。记住对于所有的基站来说，短码是一样的，但是遇到特定的掩码会使 PN码产生相对每个基站的系统时间的一个唯一的时间延迟，因此成为一个唯一的码。换句话说，这样就标识了特定的

基站，因而允许每个基站都可以复用所有 64个Walsh码，即使相邻小区也可以使用同一个频率。 5.4.8 Idle State Handoff空闲状态时切换 While on paging channel mobile has been told that other Pilot channels are available for service. The mobile scans for alternative Pilot channels at all times. The mobile can listen to two pilot channels at one time and decide using it's rake receiver which signal has the stronger field strength. The mobile will then ask system for a soft handoff to new cell site (frequency is the same but different PN short code). 在寻呼信道上，手机被告知在服务区内的可用的其它导频信道。手机总是在扫描可供选择的导频信道。手

机能同时侦听两个基站的导频信道，然后使用 Rake接收机判断哪个基站信号强度大，而决定是否切换。如果需要，手机向将向系统请求软切换到新的小区（频率相同，PN短码不同）。 6.0 Reverse Channels 反向信道

• Access Channel 接入信道 • Traffic Channel 业务信道

6.1 Access Channel:接入信道 The reverse link does not support a Pilot channel like the base station because that would mean that every mobile would need its' own Pilot and this would be impossible. Walsh codes also can not be used for channelization since the varying time delays from each mobile to BS would destroy orthogonality of the Walsh Codes. 反向链路不能象基站（前向链路）那样使用导频信道，因为那样就意味着每一个手机都需要自己的导频信

道，而这是不可能实现的。而且Walsh码也不能用来实现信道化，由于每个手机到基站的时间延迟不同，这样做会破坏Walsh码之间的正交性。 The Access channel is used by the mobile to initiate calls. Access channel messages consist of registration, order, data burst, origination, page response, authentication response, and status response. When user decides to make a call, the number is keyed in and the talk key is depressed. This initiate an Access Probe. The Access channel is a special code used to make contact with the cell site. This code was obtained from information the BS gave in the Synch and paging channel. This is really a masked long code that contains access channel number, base station ID, and pilot ON offset. Since a call still has not been established the closed loop power control is not active. The mobile will use the open loop power control to estimate the initial level. The formula for open loop power: Txpower = (-73) – (Rx'edpower) in Cell Band. In PCS band, the constant is (-76) instead. 手机使用接入信道来发起呼叫。接入信道信息包括登记、顺序、数据脉冲、发起、寻呼响应、鉴权响应和

状态响应。当用户按下通话键，决定发起呼叫时，就发起了接入探测。接入信道是一个特殊的码用来与基

站取得联系。这个码是从基站的同步和寻呼信道中发出的信息中得到的。它是一个带掩码的长码，包含了

接入信道号、基站号和导频偏移。由于通话尚未建立，还没有闭环功率控制，手机将使用开换功率控制来

估计初始发射功率值。开环功率控制的公式为：Cell频段下，发射功率 = (-73) – (接收功率)； PCS频段下，此常数是(-76)。 Each cell site has a limited # of access channel receivers available and it may be necessary for mobile to try and access a random multiple of times. The Coding for the Access channel is shown below. The Access channel message


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CDMA技术信息 data runs at 4,800 bps. This data is passed through a 3

1 rate convolutional encoder that triples the data rate to

14,400 bps. The data is then just repeated to produce a data stream of 28,800 bps and is passed through the interleaver and then sent to a 64-ary modulator. Walsh codes are not used in the reverse direction for channelization but rather to randomize data with a modulation format that is easy to recover, hence the 64-ary modulator. The data coming from the interleaver is input 6 bits at a time (6-bit word) which can have one of 64 value (1 32 1 16 1 8 1 1 1 1 ). Coincidentally there are 64 Walsh codes each being 64 bits long. So in other words it points to

one of the Walsh codes, thus increasing the data rate by ~10

4 2

× 64

6800,28 or to 307,000 bps. Since this type of

modulation can output one of 64 possible codes it is referred to as 64-ary. Next we Xor in the special Access channel long code spreading the data rate to 1.2288 Mbps which is scrambled then with the Short code or PN offset. 每个基站都包含有限数目的接入信道接收机，手机可能需要随机地尝试和接入许多次。接入信道的编码如

下图所示。接入信道信息速率是 4800bps，经过一个 1/3速率的卷积编码器后数据速率 3倍到 14,400bps。然后数据重复产生 28,800bps的数据流，经过交织器后进入 64列调制器。Walsh码在反向信道不是用来实现信道化，而是通过一种易于恢复的调制格式使数据随机化，这就是 64列调制器。从交织器出来的数据按 6比特为单位（6比特字）输入，这样得到 64个可能值。碰巧的是，正好有 64个Walsh码，每个码是 64位长

度。因此每个 6比特字正好对应一个Walsh码，这样就扩展数据速率到大约 10

× 64

6800,28

，即

307,000bps。由于这种调制器能够输出 64个不同的码其中之一，所以它被称为 64列。接下来我们同这个特定的接入信道的长码进行异或，从而将数据扩展到 1.2288Mbps，然后使用短码或 PN偏移扰码。



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Access Channel Long Code

1.2288 Mbps

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Access ChannelMessageData

28.8 kbps

WalshCode 63

WalshCode 62

WalshCode 61

WalshCode 2

WalshCode 1

WalshCode 0

6-bitword

307.2 kbps1.2288 Mbps

t/2

6-bitword6-bitword6-bitword6-bitword

After each access attempt, the mobile listens to the Paging Channel for a response from the base station. Once the base station detects the access probe from the mobile, it counters with channel assignment message. This message includes all the information for the mobile to access a traffic channel. Examples of traffic channel message from BS would be the Walsh code channel that will be used on the forward link channel, the frequency that will be used, and the frame offset which supplies the time delay between the forward and reverse link. Once the mobile acknowledges the channel assignment, BS and mobile now should be in traffic channel link and conversation taking place. If there is any information data that needs to be sent it will be done on the traffic channel from this point on. 每一次接入尝试之后，手机就在寻呼信道上倾听基站的响应。一旦基站检测到手机接入请求，就回应业务

信道配置信息。这个信息包含了手机访问业务信道的所有必要信息。比如前向链路Walsh码信道信息，频率信息，帧偏移信息提供了前向和反向链路的时间延迟。一旦手机响应了信道配置信息，基站和手机就开

始转到业务信道链路上开始对话。如果还需要交换其它的信息，从这个时候起就通过业务信道传输。 6.2 Traffic Channel业务信道 6.2.1 Reverse Vocoder 反向话音编码器 Used to convert analog voice signals to and from a digital format. The vocoder for CDMA is a variable rate with a high degree of data compression. The data rate is based on speech activity, normal telephone speech has about a 40% activity factor. When the user is talking the vocoder rate is at 9600bps and when user is pausing or listening the


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CDMA技术信息 amount of speech data is reduced to 1200 bps. The reverse vocoder will vary in output rate depending on the speech activity. To keep the speech in neat little packets, CDMA uses 20ms frames each containing up to 192 bits of information (9600 bps/ 50). Depending on the speech activity the vocoder rate will vary frame-to-frame. The mobile Vocoder recognizes four different degrees of voice content on a frame-to-frame basis and outputs sets of digitized voice parameters of four different sizes. When vocoder is running at less than 9600 bps the mobile will burst it's transmitter inconjuction with the vocoder rate. 用来将模拟的话音信号同数字格式互相转化。CDMA的声码器是变速率、高数据压缩率的声码器。数据速率基于话音状态。通常电话语音有 40%的激活因子。当用户讲话时，声码器速率是 9600bps，当用户停顿或倾听的时候，话音数据减少到 1200bps。反向声码器会根据话音状态改变输出速率。为保持话音有小而简洁的帧结构，CDMA使用 20ms帧，每个帧包含最多 192比特信息(9600bps/50)。根据话音状态，声码器的速率将会每帧每帧变化。手机的声码器认可 4种不同程度的话音内容，基于帧到帧的基础，同时输出 4种不同大小的数字话音参数组。当声码器运行速率小于 9600bps时，手机将以非连续模式脉冲地发射信号以适应声码器的速率。 6.2.2 CDMA Frames CDMA帧结构 A CDMA frame is 20ms long in duration regardless of the data rate used, and contains vocoded voice bits and some additional data. Since the vocoder is variable and can run at different rates, we will look at the different rates and how it affects transmitted output. 无论使用的数据速率是多少，一个 CDMA帧的时长是 20毫秒，其中包含了编码的话音数据和一些附加数据。由于声码器是变速率的，因此可以运行在不同的速率下。下面我们将看看不同的速率对于传输的输出

有什么影响。

1 12 8171

192 bits in a 20 ms Frame

9600 bpsFrameFull Rate

Mixed Mode bit Information bits CRCEncodertail bits

This frame contains a mixed mode bit (indicates if the frame is pure channel data or contains some signaling bits), 171 coded speech bits, 12 bits of CRC (correction bits for frame), 8 encoder tail bits (all 0's in a row to flush the contents of convolutional coder in preparation for processing the next frame). 这个帧包含一个混合模式比特（指示这个帧是纯数据信道还是包含了一些信令比特），171个编码话音比特，12个 CRC(帧纠错)比特，8个尾比特（一行全 0比特，用来给卷积编码器清零，以便为处理下一个帧做准备）。 If we take the 20 ms frame and partitioned it into 16 groups (power control groups) in full rate vocoder mode you would have 12 bits per 1.25 ms equaling 192 bits, thus transmitting continuously. 在全速率编码器模式下，如果我们把一个 20毫秒帧分成 16组（功率控制组），就可以得到每 1.25毫秒传送 12比特，相当于每 20ms传送总共 192个比特，这样就可以保证数据的连续传送。


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CDMA技术信息

12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12

192 bits in a 20 ms Frame1.25 ms 1.25 ms

Full Rate9600 bps

When in ½ rate mode we will only outputting 4800 bps from the vocoder which will result in 96 bits per frame. 当 1/2速率模式下，声码器输出 4800bps，这样每帧 96比特。

1 879


4800 bpsFrameHalf Rate

Mixed Mode bit Information bits CRC Encodertail bits

8

If you take a ½ rate vocoder and break it down into the 16 groups and instead of spreading the data evenly over the frame, say 6 bits per 1.25 ms, we will still output 12 bits per 1.25 ms thus only transmitting 50% of the time 如果使用 1/2速率声码器，也把数据分成 16组，我们仍然能够输出 12比特/1.25毫秒，而非 6比特每 1.25毫秒的平均分布，因而只有 50%的时间在传输数据。

12 12 12 12 12 12 12 12

1.25 ms 1.25 ms96 bits in a 20 ms Frame

4800 bpsHalf Rate

When in ¼ rate mode we will only outputting 2400 bps from the vocoder which will result in 48 bits per frame There is no CRC bits provided when below ½ rate frame. 当使用 1/4速率模式时，声码器输出只有 2400bps，这样每帧就只有 48比特。当速率低于 1/2时，帧内没有CRC校验位。


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CDMA技术信息

1 839


2400 bpsFrame

Quarter Rate

Mixed Mode bit Information bits Encodertail bits

Notice that the data is randomly placed within the frame. 注意此时数据放入帧内的位置是随机的。

12 12 12 12 2400 bpsQuarter Rate

1.25 ms 1.25 ms48 bits in a 20 ms Frame

When in 1/8 rate mode we will only outputting 1200 bps from the vocoder which will result in 24 bits per frame There is no CRC bits provided when below ½ rate frame. 当使用 1/8速率模式时，声码器输出只有 1200bps，这样每帧就只有 24比特。当速率低于 1/2时，帧内没有CRC校验位。

1 815


1200 bpsFrame

Eighth Rate

Mixed Mode bit Information bits Encodertail bits

12 12 1200 bpsEighth Rate

24 bits in a 20 ms Frame1.25 ms 1.25 ms


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CDMA技术信息 6.2.3 Reverse Traffic Link反向业务链路 The data rate coming from the Vocoder has a direct bearing on the transmission rate as stated above. A quick look at traffic channel reveals that it is basically formatted the same as the Access channel except we are transmitting digital voice bits and unique user masked long code. 从上面的可见，声码器输出的数据速率同传输速率有直接的关系。业务信道基本上和接入信导的格式是一

样的，除了传输的是数字话音比特和唯一的用户掩码的长码。



FIR

FIR Phas

eM

odul

ator

Q

I

1.2288 Mbps

1.2288 Mbps




14.4 kbps 28.8 kbps

User Masked Long Code

1.2288 Mbps

Long CodeScrambling28.8 kbps

WalshCode 63

WalshCode 62

WalshCode 61

WalshCode 2

WalshCode 1

WalshCode 0

6-bitword

307.2 kbps1.2288 Mbps

t/2

6-bitword6-bitword6-bitword6-bitword

Vocoder Data

9600bps

4800bps

2400bps

1200bps

6.2.4 Open Loop Power开环功率控制 When on traffic channel in call mode we use Closed Loop power control which is controlled by the BS. Open loop power control works independent of the base station. When mobile is not in a call it is constantly monitoring the BS Pilot Channel for signal strength. To achieve maximum capacity of the CDMA system it is critical to control power of every mobile to limit overall interference. Since the loss in the forward path is usually equal to the loss in the reverse path we use an open loop formula to establish a preliminary transmitting level. This level is established by the formula [-73] – [Rx power] = Tx power. An example would be if the received signal power from the BS was –85 dBm ∴ so the initial Tx for mobile would be +12dBm. In PCS band the constant is [-76] instead.

[ ] [ ] dBmdBm 128573 +=−−−

当通话时，在业务信道上我们使用由基站控制的闭环功率控制。而开环功率控制独立于基站。当手机不在

通话状态时，手机持续监测基站导频信道上的信号强度。为了获得 CDMA系统最大的系统容量，对于每个手机进行功率控制以限制整体干扰水平是非常关键的。由于在前向链路上的功率损耗通常等于反向链路的

损耗，我们可以通过开环功率控制公式建立初始的发送功率水平。这个公式是：[-73]-[接收功率]=发送功率。一个例子是如果基站接收到的信号功率是-85dBm，所以 [-73]-[-85dBm]=+12dBm，因此手机初始的发送功率应该是+12dBm。在 PCS频段，这个常量是[-76]。 6.2.5 Rake Receiver Rake接收机 CDMA takes advantage of the multipath signals by using four receiving elements to search and recombine the received signals to make a more robust version. This receiver technique is called a rake receiver correlator. One more advantage of CDMA mobiles is utilized when a hand-off to another base station is necessary, a make-before-break soft hand-off is used. The rake receiver constantly searches for and measures multi-path and neighboring signals. The multi-path signals are time adjusted then combined for a stronger total signal. The neighboring cell site signals are used to determine the best choice when a handoff when necessary. CDMA充分利用了多径信号的优点。通过使用 4个接收单元来寻找和重构接收到的信号，从而形成一个更强大的接收信号。这种接收的技术叫做 Rake接收相关器。此外 CDMA手机还用到了它的另外一个优点就是当需要切换到其它小区的时候，使用了一种先连接后切断的软切换技术。Rake接收机不断地寻找和测量多径及相邻小区的信号。多径信号在调整时间偏移后合并为一个总的较强信号。相邻小区的信号用来决定进

行切换的最佳时机。


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CDMA技术信息 7.0 HandOffs 切换 7.1 Soft Handoff 软切换

Normally CDMA hand-offs are make-before-break and either “Soft” or “Softer”. A Soft hand-off is between base stations at two different locations. A Softer hand-off is between two sectors at the same base station Figure 42, CDMA Hand-off will help explain how soft, make-before-break hand-offs are accomplished.

通常 CDMA的切换采用建立先连接后切断的方式，是“软切换”或“更软切换”。软切换是在不同位置的两个基站之间。更软切换是在同一个基站的两个扇区之间。下图，CDMA切换帮助解释了软切换的原理。

Add Threshold

Drop Threshold

E /NC OSignalMargin

Time

CDMA20.DRW

Signal ASignal B

Signal C

Once a call is established, the mobile is constantly searching for other possible cell sites that might be good candidate for soft hand-offs. A search list of neighboring base stations from the base station in use is used to look for hand-off candidates.

一旦呼叫建立起来，手机就在不断地搜寻其它可以用于软切换的候选基站。建立一个临近基站的搜

索列表，然后从中搜寻候选基站。

CDMA Soft Hand-off Initiation The following scenario describes what has to happen to get a soft hand-off. A mobile with an established call using signal A starts receiving signal B. When signal B exceeds the Add Threshold level as defined by B’s cell site, a pilot strength message is sent to cell site A from the mobile. The pilot strength message is sent on the traffic channel using either dim and burst or blank and burst signaling. The pilot strength message starts a soft hand-off. When the pilot strength message is received; base station A passes this request to the MSC (Mobile Switching Center). The MSC passes the request to station B to see if a traffic channel is available for the soft hand-off request.

CDMA软切换的发起：

下面的情形描述了如何发起一次软切换。一个手机正在使用来自信号 A的连接同时开始接收来自 B的信号。当信号 B超过由 B基站定义的“加入阈值”水平时，一个导频强度信号从手机发送到基站A。导频强度信息通过业务信道发送，使用暗淡-突发或者空白-突发信令模式。导频强度信息发起了软切换的过程。当基站 A接收到导频强度信息后，就向MSC(移动交换中心)发送请求。MSC将此请求发送到基站 B，看看 B基站是否有空闲的业务信到来接受软切换的请求。


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CDMA技术信息 CDMA Soft Hand-off

If a channel is available, cell site B sends the Walsh Code that will be assigned for the soft hand-off to the MSC. At this point base station A orders the soft hand-off by sending a hand-off direction message to the mobile using the traffic channel. When the hand-off message is acknowledged, the MSC sends the land link to base station B who then begins to send information on the assigned Walsh code traffic channel to the mobile. The mobile then receives both signals from the two cell sites, each operating on different PN offsets and Walsh coded traffic channels. The two signals are then combined by using the two pilot signals as coherent phase references. In a two way soft hand-off, two of the mobile’s rakes are used: one for each received base station At the same time both base stations are independently receiving the mobile’s signal. The demodulated signal is sent to the MSC where the two signals are compared on a frame-by-frame bases. The MSC selects the better of the two signals and sends that signal to the CODEC where it is passed to the public telephone network.

CDMA软切换的过程：

如果有空闲信道，基站 B就把需要用来赋予软切换的Walsh码发送到MSC。同时基站 A通过业务信道发出一个切换方向信息给手机以发起软切换。当切换信息得到确认后，MSC就发送陆地链路给基站 B，基站 B开始在指定的Walsh码的业务信道上发送信息给手机。此时手机会同时接收到两个基站的信号，彼此运行在不同的 PN偏移和Walsh码业务信道上。通过使用两个导频信号作为相干参考相位将两个信号合并起来。在双向软切换过程中，要使用手机的两个 Rake接收机：分别用来接收来自各自的基站信号。同时两个基站都在独立地接来自收手机的信号。经解调后的信号送到

MSC，在这里两个信号进行以帧对帧为基础的比较。MSC将选择其中一个较好的信号，将它发送到 CODEC（编解码器），从这里进入公共电话网络。

CDMA Hand-off Completion When the signal from station A degrades and goes below “Drop Threshold” the mobile sends another pilot strength message to base station B indicating that base station A’s link should be terminated. At this point the mobile is being power controlled by base station B. The mobiles' request is passed by the MSC to cell site A to terminate transmission and reception of the mobile’s signal. The mobile is now exclusively terminated with base station B.

CDMA软切换的结束：

当基站 A的信号衰落并下降到低于“取出阈值”的时候，手机就发出另一个导频强度信息给基站B，指示基站 A的链路将要终止。此时手机的功率控制将完全由基站 B进行。手机的请求通过MSC发送给基站 A，以终止基站 A同手机之间的发送和接收。此时手机已经完全切换到基站 B。

If the hand-offs are between sectors on a base station the same routine applies. It makes no difference to the mobile whether the hand-off is between sectors or cell sites.

如果切换是在同一个基站的不同扇区之间，也适用同样的规程。对于手机来说，在扇区之间或在基

站之间切换是没有什么区别的。

7.2 Hard Handoff 硬切换 Most CDMA handoffs are soft, that is make before break however some types of handoffs are break before make. An example of a hard handoff would be from CDMA to analog, the CDMA link would have to be broken before the analog link is made. A mobile can not run in CDMA and analog mode at the same time. Another type of hard handoff would be a change of CDMA channels. At present 800 Mhz cellular providers have two CDMA channels per provider.

大多数的 CDMA切换都是软切换，即先连接后切断；然而有一些切换却是先切断后连接，这就是硬切换。硬切换的一个例子是从 CDMA系统切换到模拟系统，此时 CDMA的链路必须先切断然后模拟的链路才能建立起来。手机不能够同时工作在 CDMA和模拟模式下。另外一种硬切换是切换到不同的 CDMA物理信道。由于目前的 800兆赫蜂窝系统给每个运营商分配了两个 CDMA物理信道，这种切换理论上是可以发生的。


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CDMA技术信息 8.0 Orthogonal Spreading 正交扩频

Truth Table for Exclusive -or

Input X Input Y Output

1 1 01 0 10 0 00 1 1

Orthogonal Speading at Base Station

Input Data

1 0

0000111100001111111100001111000000001111000011111111000011110000 0000111100001111111100001111000000001111000011111111000011110000

Each data bit is X'ored with a 64-bit.

Each data bit is X'ored with a 64-bitWalsh Code 20.

Walsh Code 20 Walsh Code 20

1111000011110000000011110000111111110000111100000000111100001111 0000111100001111111100001111000000001111000011111111000011110000

Pattern transmitted by the Base Station Pattern transmitted by the Base Station

Despreading of the received pattern at the Mobile Station

0000111100001111111100001111000000001111000011111111000011110000 0000111100001111111100001111000000001111000011111111000011110000

Each 64 bit block of thereceived pattern is X'ored withWalsh Code 20

1111111111111111111111111111111111111111111111111111111111111111

Each 64 bit block of thereceived pattern is X'ored withWalsh Code 20

0000000000000000000000000000000000000000000000000000000000000000

If we despead this same received pattern at the mobile but with an incorrect walsh function.

1111000011110000000011110000111111110000111100000000111100001111 0000111100001111111100001111000000001111000011111111000011110000

Despreading of the received pattern at the Mobile Station

0000000011111111000000001111111111111111000000001111111100000000

Each 64 bit block of thereceived pattern is X'ored withWalsh Code 40 which is not the same as Code used to spead at the Base Station.

1111000000001111000011111111000000001111111100001111000000001111 0000111111110000111100000000111111110000000011110000111111110000

Each 64 bit block of thereceived pattern is X'ored withWalsh Code 40 which is not the same as Code used to spead at the Base Station.

Walsh Code 40 Walsh Code 40

0000000011111111000000001111111111111111000000001111111100000000


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CDMA技术信息 9.0 Differences between IS2000 and IS95B IS2000与 IS95B的区别 CDMA2000 is also referred to as IS200, C2K and 1XRTT. This is the evolution from 2nd to 3rd generation services. The CDMA2000 networks are backwards compadible with IS95B(combintion of IS95 and J-STD-008) The motive to go to 3G networks is to deliver better performance, greater cost-effectiveness and significantly more voice and data content. CDMA2000有时也称为 IS2000，C2K或 1XRTT。这是从第二代到第三代业务的演进。CDMA2000网络向后兼容 IS95B（IS95和 J-STD-008的合并）。3G演进的动力是提供更好的服务，更高的成本效率，更高效的语音和数据业务。 This is one solution for wireless operators to take advantage of the changing markets, focusing on delivering air interface for mobile Internet access. CDMA 2000 will deliver peak data rates of 144 kbps(compared to 9.6/14.4 kbps in older standard), in the standard 1.25 MHz channel bandwidth. 这是无线运营商可以选择的一个利用变化中的市场的演进方案，专注于提供空中接口来支持移动英特网业

务。CDMA2000将可以提供峰值 144kbps的速率（相比于 GSM的 9.6/14.4kbps）在一个标准的 1.25MHz的信道带宽上。 CDMA2000 uses Radio Configuration (RC1 – RC5) intead of Rate Sets (RS1, RS2). The difference is Radio Configuration is a set of forward and reverse channels instead of single channel Rate Sets. This allows for almost twice as much voice capacity as before. CDMA2000使用无线电配置(RC1-RC5)代替了速率集(RS1, RS2)。其中的区别是无线电配置是一组前向和反向信道而速率集是单一信道。这样提供了几乎是以前 2倍的话音容量。 There are new signaling channels, and are listed below: 新的信令信道如下： Forward Link Channels 前向链路信道：

• IS-95 • Sync Channel (SYNCH) 同步信道 • Paging Channel (PCH) 寻呼信道 • Traffic Channel (TCH) 业务信道 • Pilot Channe l(PiCH) 导频信道

• CDMA2000 • Sync Channel (SYNCH) 同步信道 • Paging Channel (PCH) 寻呼信道 • Quick Paging Channel (QPCH) 快速寻呼信道

• Common Power Control Channel (CPCCH) 通用功率控制信道 • Broadcast Channel (BCH) 广播信道 • Common Control Channel (CCCH) 通用控制信道 • Dedicated Control Channel (DCCH) 专用控制信道 • Traffic Channel (TCH) 业务信道

• Fundamental Channel (FCH) 基本信道 • Supplemental Channels (SCH) 补充信道 • Supplemental Code Channels (SCCH) 补充码信道

• Pilot Channel (PiCH) 导频信道 • Auxiliary Pilot Channel (ApiCH) 辅助导频信道 • Auxiliary Transmit Diversity Pilot Channel (ATDPiCH) 辅助发送分集导频信道 • Orthogonal Transmit Diversity Pilot Channel (OTDPiCH) 正交发送分集到频信道

Reverse Link Channels 反向链路信道： • IS-95 • Acces Channel (ACH) 接入信道 • Traffic Channel (TCH) 业务信道 • CDMA2000 • Access Channel (ACH) 接入信道 • Enhanced Access Channel (EACH) 增强接入信道 • Traffic Channel (TCH) 业务信道


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CDMA技术信息 • Pilot Channel (PiCH) with Power Control Subchannel(PCsch) 导频信道包含功率控制子信道 • Fundamental Channel (FCH) 基本信道 • Supplemental Channels (SCH) 补充信道

• Supplemental Code Channels (SCCH) 补充码信道

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