目录
小区广播概念
小区广播短消息业务是移动通信系统提供的一项重要业务，通过小区广播信道（CBCH）将信息（如地理位置、天气状况等信息）传到手机，再由用户选择接收的一种功能，主要用于将信息分发到特定地理位置区域内的移动用户。GSM/UMTS支持小区广播业务，小区广播是向客户按区域、按频道发送各种实时、动态的分类信息（如登机信息、天气状况等信息）的业务。
小区广播是短信的一种类型，但有别于普通的点对点短信。
一般的点对点短消息(Short Message Service - Point to Point, SMS-PP)只能传送短消息给一个或少数几个收件人，但是小区广播技术则是被设计为能够在特定区域中，按照指定的频道(Channel)来广播消息，让许多使用者同时接收到同样的消息。因此手机仅是开启CB功能，开启Channel，被动接收来自相应Channel的小区广播消息。
小区广播特点
1、免费资讯：客户通过小区广播接收到的信息全部免费。
2、自主性：您可自主选择频道，设置不同频道的开关，接收您需要的信息。
3、区域性：可在不同的小区内接收到不同的信息。
4、覆盖范围灵活，小到一个蜂窝小区（Cell），大到整个陆地移动通信网（PLMN），覆盖范围都能够灵活调整。
5、时效快，对事故发生地点或一个城市的信息发布仅需要几秒钟。
6、接收方便，手机成为基本通信工具，提供有效的载体。
7、利用专用的广播信道进行广播，确保广播信息的迅速发布。
8、采用数字化频道划分，最大可以划分65535个频道。
GSM/UMTS 网络架构
GSM网络小区广播短消息业务基本网络结构由小区广播设备（Cell Broadcast Service Equipment，CBE）、小区广播中心（Cell Broadcast Centre，CBC）、基站控制器（BSC）、基站收发器（BTS）和移动台（MS）（即手机）共6部分构成。
UMTS网络小区广播短消息业务基本网络结构由小区广播设备（Cell Broadcast Service Equipment，CBE）、小区广播中心（Cell Broadcast Centre，CBC）、UMTS无线接入网（UTRAN）、和用户设备（UE）共4部分构成。
小区广播的分类
一般主要分为紧急小区广播和普通小区广播两种。小区广播频道总范围为 0-65535 (0x0000-0xFFFF)。
紧急小区广播
其中紧急小区广播范围如下：
PWS(Public Warning System) as defined in 3GPP TS 22.268 : 4352-6399 (0x1100-0x18FF)。
ETWS(Earthquake and Tsunami Warning System) 范围4352-4359(0x1100-0x1107), 其中4357-4359 (0x1105-0x1107) for future extension,
因此有效频道范围为4352-4356 (0x1100-0x1104)
CMAS(Commercial Mobile Alert System) 范围4370-4399 (0x1112-0x112F), 其中4396-4399 (0x112C-0x112F) for future versions,
因此有效频道范围为4370-4395(0x1112-0x112B)
PWS范围内除ETWS和CMAS以外, 4400-6399 (0x1130-0x18FF) for future versions, 目前没有被使用。
普通小区广播
其他的我们都叫普通小区广播，也就是normal cellbroadcast，具体的每个信道如下：
0 - 999:
To be allocated by GSMA(see GSMA PRD SE.15 [25]). If a Message Identifier from this range is in the "search list", the ME shall attempt to receive such CBS message.
This version of 3GPP TS 23.041 does not prohibit networks from using Message Identifiers in the range 0000 - 03E7 (hex) for Cell Broadcast Data Download to the SIM.
1000: LCS CBS Message Identifier for E-OTD Assistance Data message.
1001: LCS CBS Message Identifier for DGPS Correction Data message.
1002: LCS CBS Message Identifier for GPS Ephemeris and Clock Correction Data message.
1003: LCS CBS Message Identifier for GPS Almanac and Other Data message.
1004 - 4095:
Intended for standardization in future versions of 3GPP TS 23.041. These values shall not be transmitted by networks that are compliant to this version of 3GPP TS 23.041. If a Message Identifier from this range is in the "search list", the ME shall attempt to receive this CBS message.
4096 - 4223:
Networks shall only use Message Identifiers from this range for Cell Broadcast Data Download in "clear" (i.e. unsecured) to the SIM (see 3GPP TS 11.14). If a message Identifier from this range is in the "search list", the ME shall attempt to receive this CBS message.
(Not settable by MMI)
4224 - 4351:
Networks shall only use Message Identifiers from this range for Cell Broadcast Data Download secured according to 3GPP TS 23.048 [15] to the SIM (see 3GPP TS 11.14). If a message Identifier from this range is in the "search list", the ME shall attempt to receive this CBS message.
(Not settable by MMI)
4352:
ETWS CBS Message Identifier for earthquake warning message.
4353:
ETWS CBS Message Identifier for tsunami warning message.
4354:
ETWS CBS Message Identifier for earthquake and tsunami combined warning message.
4355:
ETWS CBS Message Identifier for test message.
The UE silently discards this message. A UE specially designed for testing purposes may display its contents.
4356:
ETWS CBS Message Identifier for messages related to other emergency types.
4357 - 4359:
ETWS CBS Message Identifier for future extension.
4360 - 40959:
Intended for standardization in future versions of 3GPP TS 23.041. These values shall not be transmitted by networks that are compliant to this version of 3GPP TS 23.041. If a Message Identifier from this range is in the "search list", the ME shall attempt to receive this CBS message.
40960 - 45055:
PLMN operator specific range. The type of information provided by PLMN operators using these Message Identifiers is not guaranteed to be the same across different PLMNs. If a Message Identifier from this range is in the "search list", the ME shall attempt to receive this CBS message.
45056 - 61439:
Intended as PLMN operator specific range in future versions of 3GPP TS 23.041. These values shall not be transmitted by networks that are compliant to this version of 3GPP TS 23.041. If a Message Identifier from this range is in the "search list", then the ME shall attempt to receive this CBS message.
61440 65534:
Intended as PLMN operator specific range in future versions of 3GPP TS 23.041. These values shall not be transmitted by networks that are compliant to this version of 3GPP TS 23.041. If a Message Identifier from this range is in the "search list", then the ME shall attempt to receive this CBS message.
(Not settable by MMI.)
65535:
Reserved, and should not be used for new services, as this value is used on the SIM to indicate that no Message Identifier is stored in those two octets of the SIM. If this Message Identifier is in the "search list", the ME shall attempt to receive this CBS message.
(Not settable by MMI.)
一般可自由定制使用的channel是在1000以下的。
