3GPP TSG RAN1#45 meeting
`Shanghai, China, 8th–12th May, 2006
`Agenda Item:
`11.3.2
`Source:
`CATT
`Title:
`Paging control and paging channels
`Document for:
`Discussion and decision
`
`R1-061537
`
`1(cid:714)Introduction
`This document discusses the paging control and paging channels. It is presented that the PCH is mapped to the
`downlink physical shared channel, and the page indicator info is carried on DSCCH. The DSCCH carrying paging
`indicators is distinguished with normal DSCCH by special UE ID such as C-RNTI. The working procedure of paging is
`also discussed in this document.
`
`2(cid:714)Discussion
`1. The Mapping of PCH and Page indicator
`
`In the TR25.813, the Paging channel is characterised by:
`
`support of UE power saving (DRX cycle is indicated by the network to the UE);
`-
`requirement to be broadcast in the entire coverage area of the cell;
`-
`- mapped to physical resources which can be also used dynamically for traffic/other control channels.
`So, PCH can be mapped to the downlink physical shared channel (DPSCH). When no paging, the downlink physical
`shared channel can carry DL-SCH to increase the efficiency of the radio resource. To enable UE power saving, there
`should be a paging indicator to indicate PCH information and UEs can listen to it in DRX pattern. Because PCH is
`mapped on DPSCH the schedule information (control signalling) of DPSCH is carried on the downlink shared control
`channel (DSCCH). We can use the DSCCH to carry the Page indicator. The page indicator should be sent in DTX mode
`(periodically), so the DSCCH carry the page indicator periodically.
`It is broadcasted on the BCH that which DSCCHs
`carry the paging indicators and what the DTX period and position is. The mapping is shown in the figure 1.
`
`PCH
`
`Transport channel
`
`DSCCH(Paging indicators)
`
`DPSCH
`
`Physical channel
`
`DPSCH
`
`DSCCH
`SFN
`
`UEx
`Data
`UEx
`1
`
`UEx
`Data
`UEx
`2
`
`UEx
`Data
`UEx
`3
`
`UEx
`Data
`UEx
`4
`
`UEx
`Data
`UEx
`5
`
`UEx
`Data
`UEx
`6
`
`UEx
`Data
`UEx
`7
`
`UEx
`Data
`UEx
`8
`
`UEx
`Data
`UEx
`9
`
`UEx
`Data
`PI
`10
`
`PCH
`Data
`UEx
`11
`
`UE1
`Data
`UEx
`12
`
`Paging DTX (no paging)
`
`Paging DTX
`
`Figure 1. PCH mapping and PI mapping
`(cid:44)(cid:81)(cid:87)(cid:72)(cid:79)(cid:79)(cid:72)(cid:70)(cid:87)(cid:88)(cid:68)(cid:79)(cid:3)(cid:57)(cid:72)(cid:81)(cid:87)(cid:88)(cid:85)(cid:72)(cid:86)(cid:3)(cid:44)(cid:44)(cid:3)(cid:47)(cid:47)(cid:38)(cid:3)(cid:40)(cid:91)(cid:17)(cid:3)(cid:21)(cid:19)(cid:19)(cid:25)(cid:3)
`(cid:40)(cid:85)(cid:76)(cid:70)(cid:86)(cid:86)(cid:82)(cid:81)(cid:3)(cid:44)(cid:81)(cid:70)(cid:17)(cid:3)(cid:89)(cid:17)(cid:3)(cid:44)(cid:81)(cid:87)(cid:72)(cid:79)(cid:79)(cid:72)(cid:70)(cid:87)(cid:88)(cid:68)(cid:79)(cid:3)(cid:57)(cid:72)(cid:81)(cid:87)(cid:88)(cid:85)(cid:72)(cid:86)(cid:3)
`(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:3)(cid:44)(cid:51)(cid:53)(cid:21)(cid:19)(cid:20)(cid:27)(cid:16)(cid:19)(cid:20)(cid:22)(cid:27)(cid:19)(cid:3)
`
`0001
`
`

`

`2. The page indicator and resource indicator for PCH
`Because the DSCCH carries both the normal control signalling and page indicators (not simultaneously, may be TDM
`mode), a method is needed for UE to identity whether it was normal control signalling or page indicator. By assigning a
`special UE-id (C-RNTI) for DSCCH carried page indicator, UE can identify the information carried on DSCCH. The
`special C-RNTI can not be assigned to UE for transferring normal data.
`
`When there is no paging information, eNB do not need to send any page indicator on DSCCH. Instead, it can be used
`for transferring scheduling information for UE in RRC_connected state.
`
`In LTE, the system is based on the shared channel. So mapping the PCH on the shared physical channel dynamically
`which also carried SCH data (not simultaneously) is a promising solution to increase the efficiency of radio resource. In
`addition, the resource info of DPSCH which carried PCH is informed to UE on the DSCCH.
`
`3. Paging control procedure
`The paging control procedure is depicted as following:
`
`If the scheduler decides to transmit a paging message, the eNB first sets the special UE-id for paging together with page
`indicator and resource indicator of the DPSCH which will carry the paging message of the DPCCH and sends it at DTX
`occasion. Then it maps the paging message on the DPSCH and sends it at the scheduled position. If scheduler decides to
`transfer a user service data or has no paging message to transfer, eNB setups the scheduled ACTIVE UE’s id and
`corresponding control signalling info and sends it at the occasion which is originally used to send page indicator. And
`then the eNB transfers service data to the ACTIVE UE.
`
`UEs in RRC_IDLE state get the information of paging channel from BCH. Then monitor the DSCCHs which carry
`page indicator periodically.
`
`When the DSCCH was received, the UE should judge the UE_ID at first. If the UE_ID is not the special C-RNTI for
`paging, it means there is no paging information and then the UE should return to sleep mode and monitor the DSCCH at
`the next DRX occasion; If the UE_ID is the special C-RNTI, it indicates there is a paging message. If the paging
`indicator indicates the message belong to their own group, the UEs will receive the DPSCH which carry the paging
`message according to the resource indicator on the DPCCH. Then MAC will judge whether the paging message is for
`itself. The whole paging procedure for Idle UE is shown in figure 2.
`
`If UEs in RRC_CONNECTION state receive the DSCCH at the page indicator occasion, they will not treat it. If the
`occasion is used by normal control signalling when no paging messages or there are higher priority service data to send,
`UEs deal it as a normal control signalling.
`
`0002
`
`

`

`IDLE UE read DSCCH in DRX
`
`Is it Special C-RNTI?
`
`Yes
`
`IDLE UE read paging indicator in DSCCH
`
`Is it our Paging?
`
`No
`
`No
`
`Go to sleep
`
`Yes
`IDLE UE read resource indicator of DPSCH in DSCCH
`
`Read PCH data in DPSCH and deal with it
`
`Figure 2. The paging procedure for Idle UE
`
`3(cid:714)Conclusion
`In this document we present a solution for paging control and paging channels. The PCH is mapped to the downlink
`physical shared channel, and the paging indicator info(cid:708)including resource indicator(cid:709) is mapped on the DSCCH in
`TDM mode. From the above depicting, it can increase the efficiency of radio resource and make the scheduling of radio
`resource very flexible. Using special C-RNTI to indicate DSCCH carrying paging indicators can make the paging
`control procedure very easily and have no impacts on ACTIVE UEs’ scheduling.
`
`4(cid:714)References
`[1]
`TR25.813 v0.8.4, Radio interface protocol aspects 2006-04
`
`[2]
`
`[3]
`
`TR25.814 v1.2.2, Physical Layer Aspects for Evolved UTRA 2006-04
`
`R2-060988, PCH mapping and Paging control, CATT RAN2#52 Athens 27-31 March, 2006
`
`0003
`
`