【请教】LTE如何区分某个service request是paging response还是mo-data/mo-signaling

hycl5410

如题。
W下service request是带service type的，可以区分该service request是哪种类型的。paging response，mo-data，mo-signaling...
但是到了EPC（24.301）service request就看不到这个指示了。那么MME如何来明确分辨某一个service request是哪种类型的呢？
个人觉得分辨这个还是有用的，因为是两种不同的触发条件（网络还是UE）。

admin

找到答案了！在TS24.301的附录D.1。主要原因是为了尽最大可能减少延迟还有就是减少空口的负担（省一个字节都能节省不少资源，LTE就这么抠），service request已经和RRC的连接建立消息合并在一起发送了，所以service request里的service type被取消了，因为RRC的连接建立也需要携带一个原因值来说明建立原因，这service type重复了。

附录D.1截取如下：

Service Request

If a SERVICE REQUEST is to request user plane radio resources, the RRC establishment cause shall be set to MO data. (See Note1)"originating calls"

If a SERVICE REQUEST is to request resources for UL signalling, the RRC establishment cause shall be set to MO data. (See Note 1)"originating calls"

If a SERVICE REQUEST is a response to paging where the CN domain indicator is set to "PS", the RRC establishment cause shall be set to MT access. (See Note 1)"terminating calls"。

hycl5410

admin 发表于 2012-8-6 21:33
找到答案了！在TS24.301的附录D.1。主要原因是为了尽最大可能减少延迟还有就是减少空口的负担（省一个字节都 ...

非常感谢！

hrbqby

同学同学!

hhyaya

学习了，谢谢！

hou3331

我在attach request消息中看到RRC-Establishment-Cause: mo-Signalling (3)，这个是什么意思哦？为什么发起UL signalling，消息类型也是MO-data？，If a SERVICE REQUEST is to request resources for UL signalling, the RRC establishment cause shall be set to MO data. (See Note 1)"originating calls"

wenliu

这是我的看法啊，规范暂时未找到。
1. Attach 时候， UE 的context还未激活，RRC目前的建立原因就是为了走通信令面的流程，激活context。所以选择mo-signalling
2.UE Attach 完成，并且default Bearer激活后，为了节省资源考虑，UE 释放了连接。但是Context还是激活状态。UE 要发送上行数据，发起 CM Service，是为了重新建立enobeB《-》SGW的用户面，所以填了 mo-data。

3. paging开始，区别于mo-data，这时候网络侧用户面数据要下发给UE。 UE 是被动的用CM-SERVICE 来建立用户面，所以用MT-DATA.

hycl5410

hou3331 发表于 2013-1-23 16:10
我在attach request消息中看到RRC-Establishment-Cause: mo-Signalling (3)，这个是什么意思哦？为什么发起 ...

我在attach request消息中看到RRC-Establishment-Cause: mo-Signalling (3)，这个是什么意思哦？为什么发起UL signalling，消息类型也是MO-data？，If a SERVICE REQUEST is to request resources for UL signalling, the RRC establishment cause shall be set to MO data. (See Note 1)"originating calls"

规范还在24.301 D.1。

Table D.1.1: Mapping of NAS procedure to establishment cause and call type

	NAS procedure	RRC establishment cause (according 3GPP TS 36.331 [22])	Call type
	Attach	MO signalling (See Note 1)	"originating signalling"
	Tracking Area Update	MO signalling (See Note 1)	"originating signalling"
	Detach	MO signalling (See Note 1)	"originating signalling"
	Service Request	If a SERVICE REQUEST is to request user plane radio resources, the RRC establishment cause shall be set to MO data. (See Note1)	"originating calls"
		If a SERVICE REQUEST is to request resources for UL signalling, the RRC establishment cause shall be set to MO data. (See Note 1)	"originating calls"
		If a SERVICE REQUEST is a response to paging where the CN domain indicator is set to "PS", the RRC establishment cause shall be set to MT access. (See Note 1)	"terminating calls"
		If a EXTENDED SERVICE REQUEST has service type set to "mobile originating CS fallback", the RRC establishment cause shall be set to MO data. (See Note1).	"originating calls"
		If a EXTENDED SERVICE REQUEST has service type set to "mobile terminating CS fallback", the RRC establishment cause shall be set to MT access. (See Note1).	"terminating calls"
		If a EXTENDED SERVICE REQUEST has service type set to "mobile originating CS fallback emergency call", the RRC establishment cause shall be set to Emergency call. (See Note1).	"emergency calls"
Note 1:      For these NAS procedures initiated by UEs of access class 12, 13 or 14 in their home country, the RRC establishment cause will be set to "High priority access AC 11 – 15". For this purpose the home country is defined as the country of the MCC part of the IMSI, see 3GPP TS 22.011 [1A]. For these NAS procedures initiated by UE of access class 11 or 15 in their HPLMN or EHPLMN, the RRC establishment cause will be set to "High priority access AC 11 – 15".

NOTE:      The RRC establishment cause can be used by the network to prioritise the connection establishment request from the UE at high load situations in the network.

为什么这么设计呢？个人理解是为了区分优先级。一般对信令的处理要比数据的优先级高那么一些。而且NOTE里也这么提了。对于EPC来说，EMM-REGISTERED之后才可能有后续的信令流程，那么对EMM处理应该会给予优先。当UE进入ECM-IDLE后，并不影响EMM状态，所以service request流程给予data级别，即使UE想发起某些信令。

chsh123

学习了~~~~~~~~~~

kongshiwen

学习了，之前一直没有深研究.