B.1.17 MME对于UE Radio Capability的管理

爱卫生

B.1.17 MME对于UE Radio Capability的管理

B.1.17.1 测试目的
验证MME在附着流程中通过eNodeB获取UE Radio Capability能力。

B.1.17.2 测试结果及分析
1) MME在Initial Context Setup Request不会携带UE Radio Capability。
2) 用户EMM状态为ECM-REGISTERED，保存的UE Radio Capability与eNodeB发送上来的一致。
（注：当UE发起Service Request时，MME会将其存储的UE radio capability通过“Initial Context Setup”发给eNodeB。通过对Attach和Service Request信令流程中的该值进行比较，可以验证此检查点。）
3) 消息跟踪能够跟踪到相应的消息，流程正确，符合详细消息流程图及其描述。

liuchaohappy

请教下楼主，为何attach的时候Initial Context Setup Request没有无线能力，而service req的时候Initial Context Setup Request有无线能力呢？不知协议这样设计是基于什么考虑

爱卫生

liuchaohappy 发表于 2013-11-14 14:15
请教下楼主，为何attach的时候Initial Context Setup Request没有无线能力，而service req的时候Initial Co ...

规范里的原文是这样说的：“

The UE Radio Capability information contains information on RATs that the UE supports (e.g. power class, frequency bands, etc). Consequently, this information can be sufficiently large (e.g. >50 octets) that it is undesirable to send it across the radio interface at every transition from ECM IDLE to ECM CONNECTED. To avoid this radio overhead, the MME stores the UE Capability information during ECM IDLE state and the MME shall, if it is available, send its most up to date UE Radio Capability information to the E-UTRAN in the S1 interface INITIAL CONTEXT SETUP REQUEST message unless the UE is performing an Attach procedure or a Tracking Area Update procedure for the "first TAU following GERAN/UTRAN Attach" or for a "UE radio capability update".

这段提到了UE Radio capability主要携带了UE所支持的无线能力比如功率级别，频率波段等等。但通常会很大，比如超过50个字节。所以该字段并不是在每次ECM-IDLE到ECM-CONNECTED的转换过程中都要传递，而MME只需要将最新的UE Radio capability信息通过S1接口的initial context setup equest消息发送下去就可以了。当然有例外，除非是针对"first TAU following GERAN/UTRAN Attach"的附着或TAU流程，又或者是一个UE radio capability update流程。

If the UE is performing an Attach procedure or a Tracking Area Update procedure for the "first TAU following GERAN/UTRAN Attach" or for "UE radio capability update", the MME shall delete (or mark as deleted) any UE Radio Capability information that it has stored, and, if the MME sends an S1 interface INITIAL CONTEXT SETUP REQUEST message during that procedure, the MME shall not send any UE Radio Capability information to the E UTRAN in that message. This triggers the E UTRAN to request the UE Radio Capability from the UE and upload it to the MME in the S1 interface UE CAPABILITY INFO INDICATION message.

这段提到了其中两个特例，针对"first TAU following GERAN/UTRAN Attach"的附着或TAU流程或UE radio capability update流程，MME应该将之前存储的UE radio capability信息删除，然后如果MME通过S1接口发送initial context setup request消息给eNodeB，那将不在该消息中携带UE Radio Capability信息。这会触发让eNodeB去向UE去要UE Radio Capability，并且将该信息通过S1接口的”UE Capability info indication"消息通知MME。

If the UE is performing a Service Request (or other) procedure and the MME does not have UE Radio Capability information available (or it is available, but marked as "deleted"), then the MME sends an S1 interface INITIAL CONTEXT SETUP REQUEST message to the E UTRAN without any UE Radio Capability information in it. This triggers the E UTRAN to request the UE Radio Capability from the UE and upload it to the MME in the S1 interface UE CAPABILITY INFO INDICATION message.”

最后提到了service request流程中是否应该携带该信息。当然，不限定service request流程，括号里还提到了包括其他的流程。

当UE发起service reuest流程时，如果MME没有UE Radio Capability信息可用（或者可用，但标记为"deleted"状态），那么MME就不会在S1接口的initial context setup request消息中偶汗UE Radio Capability信息了。这将触发让eNodeB去向UE去要UE Radio Capability，并且将该信息通过S1接口的”UE Capability info indication"消息通知MME。

paul

爱总，这个pcap报文能不能附上来学习一下，谢谢。