3GPP TSG-RAN WG1 Meeting #54bis
`Prague, Czech Republic
`29 September - 3 October 2008
`
`R1-083718
`
`Agenda item: 6.2
`
`Source:
`
`Nokia, Nokia Siemens Networks
`
`Title:
`
`Missing details of semi-persistent scheduling
`
`Document for: Discussion and Decision
`
`1
`
`Introduction
`
`This contribution discusses some further details of semi-persistent DL and UL scheduling and contains several
`proposals to complete the specification of semi-persistent scheduling.
`
`2
`
`Details of DL persistent scheduling
`
`As agreed, the persistent scheduling is configured by RRC signalling, i.e., the feature is turned on/off by RRC
`signalling, and the periodicity of the persistent allocation (PS_Period) is given by RRC signalling. The exact timing as
`well as the resources and transport format parameters are sent on L1/L2 control channel (PDCCH). The persistent
`allocation sent on PDCCH using a Semi-persistent scheduling C-RNTI (SPS C-RNTI). If the persistent DL assignment
`is missed (there is no ACK or NAK), eNB can send it again.
`
`At the beginning of the talk spurt eNB gives the UE a persistent downlink assignment for a VoIP packet by sending
`L1/L2 DL assignment which indicates that it should be stored. In other words, the PDCCH indicates whether a DL
`assigment is a persistent one or not. As agreed, the UE monitors the L1/L2 control channel in preconfigured TTIs
`(DRX). If no valid DL assignment is given to the UE, the UE is required to blindly detect whether there is an initial data
`transmission to it on the persistent resource (using the stored transport format). The retransmissions are always allocated
`using the L1/L2 control channel with SPS C-RNTI.
`
`RAN2 decided that semi-persistent resources are released explicitly by PDCCH. The details of PDCCH signalling are
`FFS.
`
`We propose that SPS release is sent on PDCCH using SPS C-RNTI and by setting the content of PDCCH into a known
`code word, e.g. all bits set to zero. Furthermore, the explicit release sent on PDCCH should be acknowledged by the UE
`by sending an ACK on UL control channel corresponding to the PDCCH.
`
`Proposal 1: SPS release is sent on PDCCH using SPS C-RNTI and by setting the contents of PDCCH (except the CRC)
`into a known code word which does not give a valid allocation. For Format 1A the following fields are set to zero:
`Distributed flag, Resource block assignment, MCS, HARQ process number, NDI, DAI (for TDD).
`
`Proposal 2: The SPS release sent on PDCCH should be acknowledged by the UE by sending normal ACK on
`PUCCH/PUSCH corresponding to the CCEs used for PDCCH.
`
`RV is signalled explicitly on PDCCH for DL allocation. For persistent allocations without PDCCH (new transmission),
`some value for RV has to be defined. RV=0 is proposed for persistent allocation. Then also RV bits can be used for
`‘virtual CRC’ on PDCCH.
`
`Proposal 3: When the UE receives a persistent (first) transmission without PDCCH, the RV is assumed to be RV=0.
`
`Ex. 1004 - TCT Mobile (US) Inc.
`TCT Mobile (US) Inc. v. Sisvel S.P.A., IPR2021-00678
`Page 1 of 2
`
`

`

`3
`
`Details of UL persistent scheduling
`
`.As agreed, the persistent scheduling is configured by RRC signalling, i.e., the feature is turned on/off by RRC
`signalling and the periodicity of the persistent scheduling is given by RRC signalling. The exact timing as well as the
`resources and transport format parameters are sent on L1/L2 control channel (PDCCH) as normal UL grant (with SPS
`C-RNTI). If the UL grant is missed (there is no UL transmission), eNB can send it again.
`
`At the beginning of the talk spurt (UE MAC notices that there is speech packet coming) UE should send an uplink
`scheduling request (SR) to the eNode B. The SR is sent on a dedicated resource. For VoIP we assume that SR resource
`is available at least every 10 ms. Then eNB gives the UE a dynamic uplink grant by sending L1/L2 UL grant. The UE
`sends the VoIP packet. After receiving the first packet and a possible BSR, the eNB knows that semi-persistent
`allocation is needed and can send a persistent UL grant. When the UE receives the persistent UL grant, then the UE
`stores the parameters and is allowed to use these parameters persistently.
`
`We propose that SPS release is sent on PDCCH using SPS C-RNTI and by setting the content of PDCCH into a known
`code word, e.g. all bits set to zero. Furthermore, the explicit release sent on PDCCH should be acknowledged by the UE
`by sending an ACK on UL control channel corresponding to the PDCCH. If the release of the SPS allocation is not
`acknowledged, eNB cannot allocate the resource to some other user since eNB cannot be sure that UE has released the
`resource. Instead eNB has to wait and see that nothing is sent by the UE on the persistent resource, i.e., DTX detection
`is needed.
`
`Proposal 4: SPS release is sent on PDCCH using SPS C-RNTI and by setting the content of PDCCH (except the CRC)
`into a known code word which does not give a valid allocation. For Format 0 the following fields are set to zero:
`Hopping flag, Resource block assignment, MCS & RV, NDI, Cyclic shift for DM RS, UL index (for TDD), CQI
`request.
`
`Proposal 5: The SPS release sent on PDCCH should be acknowledged by the UE by sending ACK on PUCCH
`corresponding to the CCEs used for PDCCH. (Notice that normally UL grants sent on PDCCH are not acknowledged.)
`
`3
`
`Conclusion
`
`Missing details for the DL persistent scheduling were described in this contribution. The following is proposed:
`
`Proposal 1: DL SPS release is sent on PDCCH using SPS C-RNTI and by setting the content of PDCCH (except the
`CRC) into a known code word which does not give a valid allocation. For Format 1A the following fields are set to
`zero: Distributed flag, Resource block assignment, MCS, HARQ process number, NDI, DAI (for TDD).
`
`Proposal 2: The DL SPS release sent on PDCCH should be acknowledged by the UE by sending normal ACK on
`PUCCH/PUSCH corresponding to the CCEs used for PDCCH.
`
`Proposal 3: When the UE receives a persistent (first) transmission without PDCCH, the RV is assumed to be RV=0.
`
`Proposal 4: UL SPS release is sent on PDCCH using SPS C-RNTI and by setting the content of PDCCH (except the
`CRC) into a known code word which does not give a valid allocation. For Format 0 the following fields are set to zero:
`Hopping flag, Resource block assignment, MCS & RV, NDI, Cyclic shift for DM RS, UL index (for TDD), CQI
`request.
`
`Proposal 5: The UL SPS release sent on PDCCH should be acknowledged by the UE by sending ACK on PUCCH
`corresponding to the CCEs used for PDCCH. (Notice that normally UL grants sent on PDCCH are not acknowledged.
`
`References
`
`[1]
`
`Ex. 1004 - TCT Mobile (US) Inc.
`TCT Mobile (US) Inc. v. Sisvel S.P.A., IPR2021-00678
`Page 2 of 2
`
`