8.2 Radio Resource Functionality (Iu mode)

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8.2.1 Radio Resource Management
  UTRAN functions are defined in TS 25.401 [53]. The radio interface protocol architecture is specified in TS 25.301 [50], and the Radio Resource Control protocol is specified in TS 25.331 [52]. TS 43.051 [74] contains an overall description of GSM/EDGE Radio Access Network.
  In the context of this specification, the term URA refers also to GRA (GERAN Registration Area) when the RAN serving an MS in Iu mode is a GERAN.
  UTRAN的功能在TS25.401定义。空中接口协议架构在TS25.301定义。TS43.051包含了整个关于GSM/EDGE RAN的描述。
  在本规范的上下文中，术语URA也可以参照为Iu模式MS提供服务的GRRAN的GRA（GERAN注册区域）。
  
8.2.2 RRC State Machine
  The RRC state machine is a description model of how the MS and the Iu mode RAN co-operate regarding RRC functionality. The RRC state describes the MS state in the Iu mode RAN. This clause contains a brief description of the RRC state machine, for more information see TS 25.303 [51].
  The RRC state machine exists as two peer entities, one in the MS and one in the Iu mode RAN. Apart from transient situations and error cases the two peer entities are synchronised. Figure 57 illustrates the main modes and states of the RRC state machine.
  RRC的状态机描述了MS和Iu模式的RAN之间关于RRC层功能的互操作。RRC状态描述了Iu模式RAN的MS状态。这个章节包含了一个关于RRC状态机的简明描述，更详细信息请参考TS25.303.
  RRC状态机存在于两个对等实体间，一个是MS另一个是Iu模式的RAN。除了传递状态和错误场景，这两个对等实体都是同步的。图例57展示了RRC状态机的主要模式和状态。

Figure 57: RRC Modes, Main RRC States and Main Mode and State Transition

  RRC Idle mode: In the Idle mode there is no connection established between the MS and the Iu mode RAN. There is no signalling between RAN and the MS except for system information that is sent from RAN on a broadcast channel to the MS. The MS can also receive paging messages with a CN identity on the PCH. There is no information of the MS stored in RAN in this mode.
  RRC Idle模式;在Idle模式下，在MS和Iu模式RAN之间没有连接建立。在RAN通过广播信道发给MS的信息中只有系统信息而没有别的信令。MS也可以通过一个PCH接收一个带有寻呼消息的核心网ID。在这个模式，没有关于MS的信息存储在RAN节点。

  RRC Connected mode: In the Connected mode the main states are Cell Connected state and URA Connected state. In this mode there is one RNC/BSC that is acting as serving RNC/BSC, and an RRC connection is established between the MS and this SRNC/SBSC.
- When the MS position is known at the cell level, the MS is in the Cell Connected state. When in Cell Connected state, the RRC connection mobility is handled by handover and cell update procedures.
- When the MS position is known at the URA level, the MS is in the URA Connected state. URA updating procedures provide the mobility functionality in this state. No dedicated radio resources are used in the URA Connected state.
  RRC连接模式：在连接模式，主要的状态是小区连接状态和URA连接状态。在这个模式，有一个RNC/BSC被担当为服务RNC/BSC，并且在MS和这个SRNC/SBSC之间建立了一个RRC连接。

- 当MS的位置精确到小区级别，MS则处于小区连接状态。当在小区连接状态，RRC连接的移动性由切换和小区更新流程来处理。

- 当MS的位置精确到URA级别，MS则处于URA连接状态。URA更新流程提供了在这个状态的移动性功能。没有专门的空口资源需要在URA连接状态下使用。

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  An MS can set the DRX cycle length that is specific to the PS domain. TS 25.304 [51b] describes how the MS shall select which DRX cycle length to use with respect to DRX cycle length requirements set by the RAN, CN PS domain and CN CS domain.
  一个MS可以设置PS域的DRX周期长度。TS25.304描述了MS应怎样选择DRX周期长度来匹配在RAN/PS域/CS域中设置的DRX周期长度要求。
  The DRX parameter information shall be indicated by the MS in the attach procedure and when changing from A/Gb mode to Iu mode also in the routeing area update procedure. The SGSN shall then in each page request send these parameters to the RNC/BSC that uses this information, and the IMSI, to calculate the correct paging group.
  DRX参数信息应由MS在附着流程以及当发生A/Gb模式到Iu模式变化的时候在RAU流程中指示。SGSN应接下来在每个寻呼请求消息中发送这些信息给RNC/BSC，来告知RNC/BSC去使用这些信息，并且携带IMSI，来计算正确的寻呼组。
  At inter SGSN change (either RA update or SRNS relocation), the DRX parameters are sent from the old SGSN to the new SGSN as part of the MM context information. Hence, unless the DRX parameters have been altered, the UE should not include the DRX parameters in the Routing Area Update message. There is one other exception to this: in order to support mobility from pre-Release 99 SGSNs, the MS shall include the DRX Parameter IE in a Routing Area Update Request message sent at RA update from GERAN to UTRAN.
  在Inter-SGSN变化时（或者是RAU或者是SRNS重选），DRX参数做为MM上下文信息的一部分由old SGSN发送给new SGSN。因此，除非DRX参数发生了变化，UE不应在RAU消息中包含DRX参数。仅仅有一个例外：为了支持R99之前的SGSN的移动性，MS应在从GERAN到UTRAN的变化中的RAU流程的RAU请求消息里包含DRX参数这个信息元素。
  At inter-SGSN RA update (e.g. from GERAN), if the network receives a DRX parameters IE from the MS in the routeing area update request message, the new SGSN shall use the information provided by the MS and shall ignore the same IE received in MM Context from the old SGSN.
  在inter-SGSN RAU(例如GERAN中的)，如果网络侧接收到MS发来的RAU请求消息如果包含了DRX参数IE，则new SGSN应使用这个信息。而应忽略从old SGSN传过来的MM上下文中相同信息元素所包含的信息。
  If the UE wishes to alter its GERAN or UTRAN/E-UTRAN DRX Parameters while in Iu mode, then it shall send a Routing Area Update Request message to the SGSN containing its new DRX Parameters. If ISR had been activated for the MS, then the MS shall deactivate ISR by setting its TIN to "P-TMSI" so that the MS performs a Tracking Area Update when it next enters E-UTRAN coverage. When the UE performs that Tracking Area Update, the MME will receive the updated DRX parameters within the MM context information sent by the old SGSN and hence the UE should not include them again in the Tracking Area Update.
  如果UE期望改变它的GERAN或Iu模式的UTRAN/E-UTRAN DRX参数，那么它应发送一个RAU请求消息给SGSN并包含它的新的DRX参数。如果ISR为这个MS激活了，那么MS应将它的TIN设置为"P-TMSI"来将ISR功能暂时去激活，这样MS在它下一次进入E-UTRAN覆盖区的时候就可以执行一个TAU。当UE执行了TAU，MME将收到从old SGSN发过来的MM上下文信息中包含的更新的DRX参数，并且UE不应再一次在TAU中包含这个值。

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   A CN node requests paging only for MSs in CMM IDLE state or PMM IDLE state. In the separate CN architecture, paging from a CN node is done independently from the state of the MS in the other CN service domain.
   一个核心网节点请求的寻呼仅针对CMM-IDLE或PMM-IDLE状态的MS。在分离的核心网架构中，一个核心网节点（例如PS）发起的寻呼和另外一个核心网域（例如CS）里面核心网节点中MS的状态无关。

   In the context of this specification, the terms RNS or RNC refer also to a GERAN BSS or BSC (respectively) when serving an MS in Iu mode.
   在本规范的上下文中，为Iu模式提供服务的RNS和RNC可以分别对应GERAN中的BSS或BSC。

   In this alternative with paging co-ordination in the RAN, the MS does not need to listen to the PCH (Paging Channel) in the RRC Connected mode, at least not when MS is allocated a dedicated channel.
   For each paging request received from a CN node, the RNC determines whether the MS has an established RRC connection or not. In order to achieve this, the context that is prepared within the SRNC for MS in RRC Connected mode must contain the IMSI, which is the common MS identity for the two CN domains.
   If no context is found for the MS, "normal PCH paging" is performed. The paging message is transferred on the paging channel, and it includes the MS paging identity received from the CN and a CN service domain type indication.
   In this alternative with paging co-ordination in the RAN, the MS does not need to listen to the PCH (Paging Channel) in the RRC Connected mode, at least not when MS is allocated a dedicated channel.（请高手翻译）
  对于从一个核心网节点来的每个寻呼请求，RNC来决定MS是否有一个已经建立的RRC连接。为了实现这个目的，在SRNC中为RRC连接模式的MS准备的上下文中一定要包含IMSI，因为这对两个核心网域来说是公共的MS 身份标识。
  如果没有找到关于MS的上下文，将执行"normal PCH paging"。寻呼消息通过寻呼信道传递，并且包含从核心网收到的关于MS的寻呼ID，以及一个CN服务域类型指示。

   If a context is found, a "CN paging message" is transferred using the existing RRC connection. This message includes a CN service domain type indication. If, potentially after repetition, this transfer is unsuccessful and if the CS domain originally triggered the paging, the RNC should decide whether to attempt "normal PCH paging" as described in clause "Unsynchronous states in the UE and the UTRAN".
  如果找到了这个上下文，将使用已经存在的RRC连接来传递一个"CN Paging消息"。这个消息包含了一个核心网服务域类型指示。如果有以后有可能重复，这个传递是不成功的，并且如果是CS域发起的这个呼叫，那RNC将决定是否按照“Unsynchronous states in the UE and the UTRAN”描述的那样尝试执行"normal PCH Paging"。

8.2.4.1 PS Paging Initiated by SGSN (Iu mode) without RRC Connection for CS

Figure 58- PS Paging by SGSN (Iu mode) Without RRC Connection for CS

   NOTE 1: Steps 2 4 are common for architecture variants using Gn/Gp based interaction with GGSN. For an S4 based interaction with S GW and P GW, procedure steps (A) are defined in clause 8.2.4.1A.
1) The 3G SGSN receives a DL PDU or downlink signalling for an MS in PMM Idle state.
   注释1：步骤2，4对于使用基于Gn/Gp接口和GGSN交互的架构是公共的。对于基于S4接口的和SGW/PGW的交互，流程步骤A在章节8.2.4.1A中定义。

1）3G SGSN收到了一个下行PDU或下行信令，要发给的对象是一个处于PMM-IDLE状态的MS。

2) The 3G SGSN sends a RANAP Paging (IMSI, P TMSI, Area, CN Domain Indicator, DRX parameters, list of CSG IDs for paging) message to each RNS belonging to the routeing area in which the MS is located. IMSI is needed by the RNS in order to calculate the MS paging group, and to identify the paged MS. If 3G SGSN assigned the P TMSI to the MS, P TMSI is also included. Area indicates the routeing area in which the MS is paged. CN Domain Indicator indicates which domain (MSC or 3G SGSN) initiated the paging message, and it represents "SGSN" in this case. DRX Parameters indicates the MS's preferred DRX cycle length. The list of CSG IDs for paging is included when the 3G SGSN is configured to support paging optimisation described in clause 5.3.9. For paging optimisation, the CSG IDs of expired CSG subscriptions and valid CSG subscriptions are both included in the list. If the MS has emergency bearer service the 3G SGSN shall not perform paging optimization.
2）3G SGSN发送一个 RANAP寻呼(IMSI、P-TMSI、区域、CN域指示符、DRX参数、用于寻呼的CSG ID列表）消息给MS所在位置RA的每个RNS。需要包含IMSI来计算MS寻呼组，并且来识别寻呼的MS。如果3G-SGSN给MS分配了P-TMSI，那应包含P-TMSI。区域指示了寻呼MS的路由区。CN域指示符指示是哪个域（MSC或3G SGSN）发起的寻呼消息，并且在这个例子里是“SGSN”。DRX参数指示了MS期望的DRX循环长度。当3G SGSN按章节5.3.9的要求配置了支持寻呼优化，则用于寻呼的CSG ID列表也要被包含。对于寻呼优化，超期的CSG签约的CSG ID以及有效的CSG签约的CSG ID都包含在列表中。如果MS有一个紧急承载业务，则3G SGSN不应执行寻呼优化。

   NOTE 2: An expired CSG subscription indicates that the MS is not allowed service in the CSG. However, since the removal of the CSG from the MS is pending, it is possible the MS will camp on that CSG and therefore the MS is still paged for the CSG.

3) The RNS controls whether the MS has an established RRC connection or not. In this case, MS has no RRC connection, so a "normal PCH paging" is performed. Paging Type 1(IMSI or P TMSI, Paging originator, CN domain ID) is transferred on the Paging channel, IMSI or P TMSI identifies the MS. Paging originator indicates whether this is core network originated paging or RAN originated paging, so it represents "CN" in this case. And CN domain ID indicates whether this paging message is for CS service or PS service, so it represents "PS" in this case.

4) The paging request triggers the Service Request procedures in the MS. The service request procedures are described in clause "Service Request Procedure (Iu mode)".
Optionally, 3G SGSN may include "Non Searching Indication" in RANAP Paging message in this case. If a "Non Searching Indication" parameter is present, the RNC will not search the established RRC connection, and just initiate "normal PCH paging".
  注释2：一个超期的CSG签约信息指示这个MS不允许在CSG中使用业务。然而，因为从MS移除CSG是挂起的，因此MS重新回到CSG来使用业务也是可能的，并且因此MS仍然为CSG寻呼。

3）RNS控制MS是否有已经建立的RRC连接。在这个例子中,MS没有RRC连接，因此将执行一个"normal PCH paging"。寻呼类型1(IMSI或P-TMSI）寻呼发起者，CN域ID）将通过寻呼信道传递，IMSI或P-TMSI识别出MS。寻呼发起者指明了是核心网发起还是RAN发起的寻呼。在这个例子里是核心网发起的。并且CN域ID指示了这个寻呼消息来自CS还是PS业务。在这个例子中是PS。

4）寻呼请求将触发MS发起Service Request流程。Service Request流程在章节"Service Request Procedure(Iu mode)"中描述。

8.2.4.1A Serving GW Triggered Paging (Iu mode) with S4

Figure 58a- Serving GW triggered paging with S4

A) If the S GW has no downlink user plane TEIDs for S4 and S12, the S GW buffers the DL PDUs and identifies which SGSN is serving that UE.
   If that SGSN has requested the S-GW to throttle downlink low priority traffic and if the downlink data packet is received on a low priority bearer to be throttled (see clause 5.3.6.5), the S GW drops the downlink data packet and may send an ICMP packet to signal to the source that there is no use in repeating the packet. The steps below are not executed.
  Otherwise the S GW sends a Downlink Data Notification to the SGSN.
  If the S GW has downlink user plane TEIDs for S4 the DL PDUs are transferred to SGSN.

A)如果SGW没有S4和S12接口的下行用户面TEID，SGW将缓存下行PDU并且识别出是哪个SGSN为这个UE服务。

  如果SGSN请求SGW将那些信令数据中具有低优先级的流量扼杀掉，并且将通过一个低优先级的承载收到的数据流量扼杀掉（参考章节5.3.6.5），SGW将丢弃下行数据报文并且返回一个ICMP报文来告诉源端。下面的步骤将不被执行。

  否则的话SGW发送一个下行数据通知给SGSN。

  如果SGW有S4接口下行数据用户面的TEID，则下行PDU将传递给SGSN。

8.2.4.2 PS Paging Initiated by 3G SGSN With RRC Connection for CS

Figure 59- PS Paging by SGSN (Iu mode) With RRC Connection for CS

  NOTE 1: Steps 2 4 are common for architecture variants using Gn/Gp based interaction with GGSN and using S4 based interaction with S GW and P GW. For an S4 based interaction with S GW and P GW, procedure steps (A) are defined in clause 8.2.4.1A.
1) The 3G SGSN receives a DL PDU or downlink signalling for an MS in PMM Idle state.
2) The 3G SGSN sends a RANAP Paging (IMSI, P TMSI, Area, CN Domain Indicator, DRX parameters, list of CSG IDs for paging) message to each RNS belonging to the routeing area in which the MS is located. IMSI is needed by the RNS in order to calculate the MS paging group. If 3G SGSN assigned the P TMSI to the MS, P TMSI is included, and it identifies the MS is paged. Area indicates the routeing area in which the MS is paged. CN Domain Indicator indicates to which domain (MSC or 3G SGSN) the paging was initiated, and it represents "3G SGSN" in this case. DRX Parameters indicates whether or not the MS uses discontinuous reception and the DRX cycle length. The list of CSG IDs for paging is included when the 3G SGSN is configured to support paging optimisation described in clause 5.3.9. For paging optimisation, the CSG IDs of expired CSG subscriptions and valid CSG subscriptions are both included in the list. If the MS has emergency bearer service the 3G SGSN shall not perform paging optimization.
  注释1：步骤2，4对于使用基于Gn/Gp接口和GGSN交互的架构是公共的。对于基于S4接口的和SGW/PGW的交互，流程步骤A在章节8.2.4.1A中定义。

1）3G SGSN收到了一个下行PDU或信令要发给一个PMM-IDLE状态的MS。

2）3G SGSN发送一个RANAP寻呼（IMSI、P-TMSI、区域、CN域指示符、DRX参数、用于寻呼的CSG ID列表）消息给MS所在位置RA的每个RNS。需要包含IMSI来计算MS寻呼组，并且来识别寻呼的MS。如果3G-SGSN给MS分配了P-TMSI，那应包含P-TMSI。区域指示了寻呼MS的路由区。CN域指示符指示是哪个域（MSC或3G SGSN）发起的寻呼消息，并且在这个例子里是“SGSN”。DRX参数指示了MS期望的DRX循环长度。当3G SGSN按章节5.3.9的要求配置了支持寻呼优化，则用于寻呼的CSG ID列表也要被包含。对于寻呼优化，超期的CSG签约的CSG ID以及有效的CSG签约的CSG ID都包含在列表中。如果MS有一个紧急承载业务，则3G SGSN不应执行寻呼优化。

NOTE 2: An expired CSG subscription indicates that the MS is not allowed service in the CSG. However, since the removal of the CSG from the MS is pending, it is possible the MS will camp on that CSG and therefore the MS is still paged for the CSG.
3) The RNS controls whether the MS has an established RRC connection or not. In this case, MS has an established RRC connection for CS service, so RNS sends an RRC Paging Type 2 (CN domain ID) message to the MS on established RRC connection. CN Domain ID indicates to which domain (CS or PS) the paging shall be directed, so it represents "PS" in this case.
4) The paging request triggers the Service Request procedures in the MS. The service request procedures are described in clause "Service Request Procedure (Iu mode)".
   注释2：一个超期的CSG签约信息指示这个MS不允许在CSG中使用业务。然而，因为从MS移除CSG是挂起的，因此MS重新回到CSG来使用业务也是可能的，并且因此MS仍然为CSG寻呼。

3）RNS控制MS是否有已经建立的RRC连接。在这个例子中,MS有一个已经建立的RRC连接用于CS业务，因此RNS发送一个RRC寻呼类型2（CN域ID）消息通过已经建立的RRC连接发给MS。CN域ID指示了这个寻呼消息来自CS还是PS业务。在这个例子中是PS。

4）寻呼请求将触发MS发起Service Request流程。Service Request流程在章节"Service Request Procedure(Iu mode)"中描述。

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   An MS in RRC URA/GRA connected state is paged by the RAN before a downlink transfer to that MS. The URA/GRA paging procedure shall move the RRC state to Cell Connected to allow the RAN to forward downlink data or signalling message to the radio resource. Therefore, the RRC: Cell Update message from the MS that moves the RRC State at the RAN to Cell Connected state is a valid response to URA/GRA paging.
   The RAN supervises the paging procedure with a timer. If the RAN receives no response from the MS to the URA or GRA Paging Request message, it shall repeat the paging. The repetition strategy is implementation dependent. If it is unsuccessful and if the paging was originally triggered by the CS domain, it is the RNC's responsibility to recover this situation by following the "normal PCH paging" mechanism (see clause "Paging Initiated by CN"). For more information see TS 25.303 [51].
   The URA/GRA Paging procedure is illustrated in Figure 60.
   RAN将在把下行数据传递给MS之前，对一个URA/GRA连接状态的MS发起寻呼。URA/GRA寻呼流程将RRC状态切换到"Cell Connected"来允许RAN转发下行数据或信令消息给空口的资源。因此，RRC:从MS来的小区更新消息将作为一个有效的对URA/GRA寻呼的响应，并将把RAN侧的RRC状态切换到"Cell Connected"状态。
   RAN通过一个计时器来监管寻呼流程。如果RAN没有收到MS对URA或GRA寻呼请求消息的响应，它将重复寻呼MS。重复的策略是由具体的实现决定的。如果不成功并且如果寻呼是由CS域发起的，这将是RNC的职责，通过"normal PCH paging"机制来恢复（参考章节“核心网发起的寻呼”）。更多信息参考TS25.303.
  URA/GRA寻呼流程在图例60描述。

Figure 60- URA_GRA Paging Procedure

1) The RAN receives a downlink PDP PDU for an MS in RRC URA/GRA connected state. Downlink signalling to an MS in RRC URA/GRA connected state initiates URA/GRA paging as well.
2) The RAN pages the MS with one Paging Type 1 (RNTI, Paging originator) message in each cell belonging to the URA/GRA where the MS exists. RNTI is the identifier by which the MS is paged. Paging originator indicates whether this is the core network originated paging or RAN originated paging, so it represents "RAN" in this case.
3) The paging request triggers the Cell Update procedures in the MS. The Cell Update procedures are described in TS 25.331 [52].

1）RAN侧接收到一个下行方向的PDP PDU要发送给一个RRC URA/GRA连接状态的MS，或者是发给RRC URA/GRA连接模式状态的MS的下行信令消息都会发起一个URA/GRA的寻呼。

  2）RAN发送一个Paging类型1(RNTI、寻呼发起者）的寻呼消息，这个消息在MS所在的URA/GRA并且是属于这个URA/GRA每个小区中发送。RNTI是用于寻呼时对MS的标识。寻呼发起者指示了是由核心网发起的还是RAN侧发起的寻呼，在本例中为“RAN”。

  3）寻呼请求触发MS执行一个小区更新流程。小区更新流程在TS25.331中描述。

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