R2-072183
`
`3GPP TSG RAN WG2#58
`Kobe, Japan, 07-11 May 2007
`
`Title:
`Response to:
`
`Source:
`To:
`Cc:
`WI:
`
`System Information
`
`Samsung
`TSG RAN1
`
`SAE/LTE
`
`Contact Person:
`Name:
`Gert-Jan van Lieshout
`Phone:
`+31 (0) 570615651
`E-mail Address: gert.vanlieshout@samsung.com
`Attachments:
`—
`
`Introduction
`During RAN2#58 RAN2 has taken several decisions w.r.t. the provisioning of system information in LTE. With
`this liaison we would like to inform RAN1 about this progress and request RAN1 to look into several questions
`that came up during these discussions.
`Decisions made in RAN2#58
`For the questions in this liaison, the following RAN2 decisions are relevant:
`
`1. RAN2 confirmed the approach of having information on the P-BCH transport channel periodically. The
`information content of the P-BCH is now called “MIB”, and a periodicity/TTI of 40ms is currently
`assumed.
`
`2. RAN2 also confirmed the approach that the remaining broadcast system information is provided on
`BCCH over DL-SCH. On the BCCH over DL-SCH, the information is structured in “Scheduling Units”
`(SU), where an SU consists of one or more System Information Blocks (SIBs).
`
`3. One complete SU may be sent in one DL-SCH transmission (1 TB in 1 subframe), or an SU can be
`segmented in which case one segment is sent in 1 TB in a subframe, with different segments provided
`in consecutive subframe’s.
`
`4. For the BCCH over DL-SCH, there will be 1 PDCCH allocation per SU or SU-segment in a subframe
`(using the BCCH RNTI). Further optimisations can be considered later.
`
`For information, in the end of this liaison, the remaining RAN2 decisions made during RAN2#58 w.r.t. system
`information are indicated.
`
`Questions
`RAN2 assumes that it should be possible for an eNB to schedule BCCH over DL-SCH and DL-SCH-unicast
`transmissions in the same TTI. This will allow unicast transmissions to continue relatively normally even while
`BCCH over DL-SCH transmissions are provided during potentially quite many consecutive TTI’s.
`
`Question 1:
`
`RAN2 was wondering whether it would be possible for a UE to receive in parallel a BCCH over
`DL-SCH transmission and a DL-SCH-unicast transmission provided in the same TTI ?
`
`RAN2 assumes that when the situation arises that one SU (e.g. a last segment of an SU) is not completely
`filling a subframe, it might be preferable to schedule one or more other SU’s (or SU-segment) in the same
`subframe.
`
`Question 2:
`
`RAN2 was wondering whether it would be possible for a UE to receive more than 1 SU (or SU-
`segment) i.e. different TB transmissions, if multiple SU (or SU-segments) are scheduled in the
`
`1
`
`APPLE 1005
`
`

`

`Question 3:
`
`same subframe ? If the answer is “yes”, how many SU’s (or SU-segments) could be received
`by a UE in parallel ?
`If the answers to the above questions 1) and 2) is “yes”, how many SU’s (or SU-segments)
`would a UE be able to receive in addition to a DL-SCH unicast transmission ?
`
`
`Then w.r.t. the P-BCH:
`
`Question 4: RAN2 was wondering whether it would be possible for a UE to receive in parallel a P-BCH
`transmission and a DL-SCH-unicast transmission provided in the same subframe (in the
`serving cell) ?
`
`Actions
`To RAN1: RAN2 would kindly like to ask RAN1 to answer the indicated questions.
`
`Furthermore, RAN2 has realised that since the BCCH over DL-SCH transmissions have to be receivable for all
`UE classes, these transmissions should not exceed the minimum UE capabilities in this respect. RAN2
`assumes it is the responsibility of RAN1 to define the minimum UE capability in this respect, and thus e.g.
`determine what can be the maximum rate on BCCH over DL-SCH ?
`
`Dates of Next TSG-RAN2 Meetings:
`25th – 29th June 2007
`TSG-RAN2 Meeting #58bis
`20th – 24th August 2007
`TSG-RAN2 Meeting #59
`
`BCCH over DL-SCH
`
`Orlando, USA
`Athens, Greece
`
`2
`
`

`

`Other RAN2 decisions made during RAN2#58 w.r.t. System Information
` The P-BCH is sent every 40ms (working assumption). If later studies show that this is too long, this will
`be revisited towards 20ms. The PLMN list is sent on D-BCH every 80ms. This will be captured in the
`stage 2
` SU1 is sent on the D-BCH
` No need for secondary BCH
` Periodicity of SU-1 is 80ms; it contains the PLMN list.
` SU1 contains a scheduling block providing the periodicity for all the SU-n>1.
` SU1 contains the mapping of SIBs into SUs, dynamic, or mapping of SIBs into SUs is fixed in the
`standard. This is FFS.
` SU1 contains a value tag for each individual SU or (MIB or SU1) contains a value tag for all the SUs
`(FFS which of the solutions is selected).
` SU-1 is in the following sub-frame of P-BCH.
` Unicast DL-SCH transmissions can take place in parallel to SUs transmission, using L1/L2 control
`channel.
` Maximum D-BCH rate = minimum UE capability; Maximum D-BCH rate has to be studied. => RAN1
` SUs can be segmented, in which case each segment is sent in the next sub-frame as the previous one
`i.e. continuous time transmission (RB can vary using L1/L2 control channel)
` Whether SUs are contiguous (in a row) is FFS (benefit of continuous transmission is UE battery
`saving)
`Information on P-BCH is called MIB
`
`
`
`
`
`3
`
`