本帖最后由 爱卫生 于 2011-4-16 10:32 编辑
When the 3G SGSN receives a downlink packet (e.g. Request PDP Context Activation, Mobile-terminated SMS, user data) for an MS in PMM IDLE state, the 3G SGSN sends a paging request to RAN. The paging request triggers the Service Request procedure in the MS.
当3G SGSN接收到下行数据包(例如请求PDP上下文激活、手机接收的短信、用户数据),要发送给PMM-IDLE状态的MS,3G SGSN发送寻呼请求给RAN.寻呼请求将出发MS的Service Request流程。
Figure 51: Network Initiated Service Request Procedure NOTE 1: All steps in figure 51, except Procedure steps (A) and (B), are common for architecture variants using Gn/Gp based interaction with GGSN and using S4 based interaction with S GW and P GW.
NOTE 2: Procedure steps B (step 7) in figure 51 above are common for MS and Network initiated service request using S4 and are described in clause 6.12.1A. Procedure steps (A) are defined in clause 8.2.4.1A when S4 is used.
注释1:所有在图例51的步骤,除了A和B以外,对于基于Gn/Gp接口和GGSN的交互的架构,还是对于基于S4接口和SGW/PGW的交互的架构,都是公共的步骤流程。 注释2:图例51中的流程步骤B,对于在章节6.12.1A描述的使用S4接口的MS和网络侧发起的service request也是公共的。流程步骤A当使用S4接口时的说明,在章节8.2.4.1A中定义。 If a LIPA PDP context exists, when the L-GW receives the downlink data for an MS in PMM-IDLE state, the L GW sends the first downlink user packet to the SGSN and buffers all other downlink user packets. When S4 is used, the L-GW sends the first downlink user packet to Serving GW and the Serving GW will trigger the SGSN to page the UE.
如果一个LIPA PDP上下文存在,当LGW接收到PMM-IDLE状态MS的下行数据,LGW发送一个下行用户数据报文给SGSN并且缓存其他的下行用户数据。当使用S4接口时,LGW发送第一个下行用户数据给SGW并且SGW将出发SGSN去寻呼UE。 1) The SGSN receives a downlink PDP PDU for an MS in PMM IDLE state.
2) The SGSN sends a Paging message to the RNC. The RNC pages the MS by sending a Paging message to the MS. See clause "PS Paging Initiated by 3G SGSN without RRC Connection for CS" for details.
3) The MS establishes an RRC connection if none exists for CS traffic. 1)SGSN接收到一个PMM-IDLE状态的MS的一个下行PDP PDU。 2)SGSN发送一个寻呼消息给RNC。RNC发送寻呼消息给MS来寻呼这个MS。参考章节"PS Paging Initiated by 3G SGSN without RRC Connection for CS"得到细节描述。 3)MS上,如果不存在为CS流量的RRC连接的话,则建立一个RRC连接。
4) The MS sends a Service Request (P TMSI, RAI, CKSN, Service Type) message to the SGSN. Service Type specifies Paging Response. The Service Request is carried over the radio in an RRC Direct Transfer message and over the Iu interface in the RANAP Initial MS message. At this point, the SGSN may perform the authentication procedure. The SGSN knows whether the downlink packet requires RAB establishment (e.g. downlink PDU) or not (e.g. Request PDP Context Activation or Mobile-terminated SMS).
CSG ID is provided if the MS attaches via a CSG cell or hybrid cell. CSG access mode is provided if the MS sends the Service Request message via a hybrid cell. If the CSG access mode is not provided but the CSG ID is provided, the SGSN shall consider the cell as a CSG cell.
If a CSG ID is indicated and CSG access mode is "closed" or CSG access mode is not provided, and there is no subscription data for this CSG ID or the CSG subscription is expired, the SGSN rejects the Service Request with an appropriate cause. The MS shall remove the CSG ID of the cell where the MS has initiated the service request procedure from the Allowed CSG list, if present.
For MSs with emergency PDP contexts, i.e. at least one PDP Context has an ARP value reserved for emergency services, and if CSG access restrictions do not allow the MS to get normal services, the SGSN shall deactivate all non-emergency PDP contexts and accept the Service Request.
4)MS发送Service Request(P-TMSI,RAI,CKSN,Service Type)消息给SGSN.Service Type指明了这是一个寻呼响应。Service Request通过空中接口承载,并封装到RRC Direct Transfer消息中,并做为Iu接口的RANAP协议的RANNAP PDU,做为初始MS消息来传送。在这个点上,SGSN可以执行鉴权流程。SGSN知道是否这个下行数据报文需要RAB建立(例如下行PDU)或不需要建立(例如请求PDP上下文建立或MS接收的短信). CSG ID当MS通过一个CSG小区或混杂小区附着时则应提供。CSG接入模式是当MS在一个混杂小区内发送service request消息时则应提供。如果CSG接入模式没有提供,但提供了CSG ID,SGSN应认为这个小区是一个CSG小区。 如果指示了CSG ID并且CSG接入模式是"closed"或者CSG接入模式未提供,并且没有它的签约数据或CSG相关的签约数据超时,SGSN应拒绝service request并带上合适的原因。UE应在允许的CSG列表中移除这个小区的CSG ID。 对于带有紧急PDP上下文的MS,也就是至少有一个PDP上下文带有为紧急业务预留的ARP值,并且CSG接入限制不允许MS来得到正常服务,SGSN应将所有非紧急PDP上下文去激活并接受这个service request。 5) The SGSN shall perform the security mode procedure. 5)SGSN应执行安全模式流程。
6) If resources for the PDP contexts are re-established, the SGSN sends a Radio Access Bearer Assignment Request (RAB ID(s), TEID(s), QoS Profile(s), SGSN IP Address(es), UE-AMBR, CSG Membership Indication, MSISDN, APN, Charging characteristics) message to the RNC. If Direct Tunnel is established the SGSN provides to the RNC the GGSN's User Plane Address and TEID for uplink data. The RNC sends a Radio Bearer Setup (RAB ID(s)) to the MS. The MS responds by returning a Radio Bearer Setup Complete message to the RNC. The RNC sends a Radio Access Bearer Assignment Response (RAB ID(s), TEID(s), RNC IP Address(es)) message to the SGSN in order to indicate that GTP tunnels are established on the Iu interface and radio access bearers are established between the RNC and the MS. If the RNC returns a Radio Access Bearer Assignment Response message with a cause indicating that the requested QoS profile(s) can not be provided, e.g. "Requested Maximum Bit Rate not Available", the SGSN may send a new Radio Access Bearer Assignment Request message with different QoS profile(s). The number of re-attempts, if any, as well as how the new QoS profile(s) values are determined is implementation dependent. MSISDN, APN and Charging characteristics are optional parameters and only transferred if SGSN supports SIPTO at Iu-ps.
If the Service Request is performed via a hybrid cell, the CSG Membership Indication indicating whether the UE is a CSG member shall be included. Based on this information the RAN can perform differentiated treatment for CSG and non-CSG members.
If the MS is not allowed to access the cell where the MS initiated the service request due to CSG access restriction, the SGSN shall only request to establish radio access bearers for Emergency PDP contexts.
6)如果这个PDP上下文的资源需要重建,SGSN发送RAB Assignment Request(RAB ID、TEID、QOS Profile、SGSN地址、UE-AMBR、CSG成员指示、MSISDN、APN、计费特征)消息给RNC。如果要建立直接隧道,SGSN则给RNC提供GGSN用户面地址和TEID用于上行数据。RNC发送Radio Bearer Setup(RAB ID)消息给MS。MS发送一个Radio Bearer Setup Complete消息给RNC做为响应。RNC发送RAB Assignment Response(RAB ID、TEID、RNC地址)消息给SGSN,用于指示这个GTP隧道已经在Iu接口建立,并且RAB也已经在RNC和MS之间建立。如果RNC返回了一个RAB Assignment消息并带有一个原因值说明请求的QOS profile不能提供,例如"请求的MBR不可用",SGSN可以发送一个新的带有不同QOS profile值的RAB Assignment请求消息给RNC。重试的次数,以及新的QOS profile的值怎样取值,取决于具体的实现。MSISDN、APN和计费特征是只有在Iu-PS下,SGSN支持SIPTO时,才带的可选字段。 如果Service Request是通过一个混杂小区执行的,"CSG Membership Indication"指示UE是否是一个CSG成员将被包含在消息中。根据这个信息,RAN可以执行CSG和非CSG成员的不同QOS待遇。
如果MS因为CSG接入限制不允许接入这个它发起service request的小区,SGSN应只请求为紧急PDP上下文建立RAB。 7) For each RAB re-established with a modified QoS profile, the SGSN initiates a PDP Context Modification procedure to inform the MS and the GGSN of the new negotiated QoS profile for the corresponding PDP context. If SGSN established Direct Tunnel in step 6) it shall initiate a PDP Context Update procedure to the GGSN and provide to the GGSN the RNC's Address for User Plane and TEID for Downlink data and shall include the DTI to instruct the GGSN to apply Direct Tunnel specific error handling procedure as described in clause 13.8.
7)对于每一个带有修改的QOS profile要求重建的RAB,SGSN发起一个PDP Context Modification流程来通知MS和GGSN关于相应的PDP上下文的新的协商的QOS profile。如果SGSN在第6步建立了直接隧道,它将发起PDP Context Update流程到GGSN,并给GGSN提供RNC上用户下行数据的用户面地址和TEID,并应包含DTI来指示GGSN要应用直接隧道。相关错误处理流程在章节13.8描述。 8) The SGSN sends the downlink packet. For a LIPA PDP context, after the MS enters connected mode, the packet buffered in SGSN/Serving GW is forwarded to the HNB if it is the same cell where the L-GW is collocated and the packets buffered in the L-GW are forwarded to the HNB on the direct path. If the MS enters connected mode at a different cell than the one where the L-GW is collocated, the SGSN shall deactivate the LIPA PDP context and the packet buffered in the SGSN/Serving GW is dropped.
For Service Type = Page Response, the MS knows that the Service Request message was successfully received in the SGSN when the MS receives the RRC Security Mode Control Command message.
If the SGSN fails to re-establish RAB(s) for the PDP context(s), the SGSN determines if an SM procedure, such as SGSN-Initiated PDP Context Modification or PDP Context Deactivation, should be initiated. The appropriate action depends on the QoS profile of the PDP context and is an operator choice.
8)SGSN发送下行数据报文。对于一个LIPA PDP上下文,在MS进入连接状态之后,如果LGW所在的小区和缓存在LGW上的数据包到将转发给HNB的直接路径在相同小区的话,缓存在SGSN/SGW中的数据包将转发给HNB(Home NodeB)。如果MS进入连接状态,但和LGW所在的小区不同,SGSN应去激活LIPA PDP上下文,并且缓存在SGSN/SGW的数据报文将被丢弃。 对于Service Type=寻呼响应,当MS收到RRC Serurity Mode Control Command消息时,MS就知道Service Request消息成功的被SGSN收到了。 如果SGSN为这个PDP上下文重建RAB失败,SGSN决定一个SM(会话管理)流程,例如SGSN发起的PDP Context Modification或PDP Context Deactivation应被触发。适当的行动取决于PDP上下文的QOS profile并且这个是一个运营商的选择。 |