14.2.4 UE procedure for determining resource block pool for PSCCH in sidelink transmission mode 3 and 4
36.2133GPPEvolved Universal Terrestrial Radio Access (E-UTRA)Physical layer proceduresRelease 17TS
The following procedure is used for sidelink transmission mode 3 and 4.
If a pool is (pre)configured such that a UE always transmits PSCCH and the corresponding PSSCH in adjacent resource blocks in a subframe, the PSCCH resource m is the set of two contiguous resource blocks with the physical resource block number 
for j=0 and 1 where 
and 
are given by higher layer parameters startRBSubchannel and sizeSubchannel, respectively.
If a pool is (pre)configured such that a UE may transmit PSCCH and the corresponding PSSCH in non-adjacent resource blocks in a subframe, the PSCCH resource m is the set of two contiguous resource blocks with the physical resource block number 
for j=0 and 1 where 
is given by higher layer parameter startRBPSCCHPool.
14.3 Physical Sidelink Discovery Channel related procedures
14.3.1 UE procedure for transmitting the PSDCH
If a UE is configured by higher layers to transmit PSDCH according to a PSDCH resource configuration, in a PSDCH period 
,
– the number of transmissions for a transport block on PSDCH is 
where 
is given by the higher layer parameter numRetx-r12, and each transmission corresponds to one subframe belonging to a set of subframes, and in each subframe, the PSDCH is transmitted on two physical resource blocks per slot.
– for sidelink discovery type 1,
– the allowed values for PSDCH resource selection are given by 0,1… 
, where
and 
, and
– the j-th transmission (
) for the transport block occurs in contiguous resource blocks 
and 
of subframe 
of the PSDCH period, where
– 
and 
and using selected resource value 
(described in [8]).
– 
,
,
and
are described in Clause 14.3.3.
– for sidelink discovery type 2B,
– The j-th transmission (
) for the transport block occurs in contiguous resource blocks 
and 
of subframe 
of the PSDCH period, where
– 
– 
– 
for 
– 
and 
, and
,
,
and
are described in Clause 14.3.3.
– 
and 
are given by higher layer parameters discPRB-Index and discSF-Index, respectively and that associated with the PSDCH resource configuration.
– 
,
and
are given by higher layer parameters a-r12, b-r12, and c-r12, repectively and that are associated with the PSDCH resource configuration.
– 
is the number of PSDCH periods since 
was received.
– the transport block size is 232
For sidelink discovery, the UE transmit power 
for PSDCH transmission is given by the following
[dBm]
where 
is defined in [6], and 
=2 and 
where
is defined in Clause 5.1.1.1 where 
is the serving cell if the sidelink discovery transmission occurs on the uplink carrier frequency of a serving cell, or
is the cell indicated by higher layers on downlink carrier frequency indicated by discCarrierRef-r13[11] if sidelink discovery transmission does not occur on the uplink carrier frequency of a serving cell.
and 
are provided by higher layer parameters p0-r12 and alpha-r12, respectively and are associated with the corresponding PSDCH resource configuration.
A UE shall drop any PSDCH transmissions that are associated with sidelink discovery type 1 in a sidelink subframe if the UE has a PSDCH transmission associated with sidelink discovery type 2B in that subframe.
14.3.2 UE procedure for receiving the PSDCH
For sidelink discovery type 1, for each PSDCH resource configuration associated with reception of PSDCH, a UE configured by higher layers to detect a transport block on PSDCH can decode the PSDCH according to the PSDCH resource configuration.
For sidelink discovery type 2B, for each PSDCH resource configuration associated with reception of PSDCH, a UE configured by higher layers to detect a transport block on PSDCH can decode the PSDCH according to the PSDCH resource configuration.
14.3.3 UE procedure for determining resource block pool and subframe pool for sidelink discovery
A PSDCH resource configuration for transmission/reception is associated with a set of periodically occurring time-domain periods (known as PSDCH periods). The i-th PSDCH period begins at subframe with subframe index
and ends in subframe with subframe index 
, where
– 
,
– the subframe index is relative to subframe#0 of a radio frame corresponding to SFN 0 of the serving cell or DFN 0 (described in [11]),
– 
is the offsetIndicator-r12 indicated by the PSDCH resource configuration
– 
is the discPeriod-r12 indicated by the PSDCH resource configuration.
For a PSDCH period, the UE determines a discovery pool consisting of a subframe pool and a resource block pool for PSDCH as follows.
– For TDD, if the parameter tdd-Config-r12 is indicated by the PSDCH resource configuration, the TDD UL/DL configuration used for determining the subframe pool is given by the parameter tdd-Config-r12, otherwise, the TDD UL/DL configuration used for determining the subframe pool is given by the UL/DL configuration (i.e. parameter subframeAssignment) for the serving cell.
– A bitmap 
is obtained using
, for 
, where 
and 
are the bitmap and the length of the bitmap indicated by subframeBitmap-r12, respectively, and 
, where 
is the numRepetition-r12 indicated by the PSDCH resource configuration.
– The first 
uplink subframes are denoted by 
arranged in increasing order of subframe index.
– A subframe 
(
) belongs to the subframe pool if 
. The subframes in the subframe pool are denoted by
arranged in increasing order of subframe index and 
denotes the number of subframes in the subframe pool.
– A PRB with index 
(
) belongs to the resource block pool if
or if 
, where S1, S2, and M denote the prb-Start-r12, prb-End-r12 and prb-Num-r12 indicated by the PSDCH resource configuration respectively.
– The resource blocks in the resource block pool are denoted by
arranged in increasing order of resource block indices and 
is the number of resource blocks in the resource block pool.
14.4 Physical Sidelink Synchronization related procedures
The synchronization resource configuration(s) for the UE are given by the higher layer parameter SL-SyncConfig-r12 or v2x-SyncConfig.
A UE shall transmit sidelink synchronisation signals according to Clause 5.10.7 in [11].
A UE may assume that sidelink synchronization signals are signals transmitted by an eNB as described in Clause 6.11 of [3] or are signals transmitted by a UE as described in [11].
A UE is not expected to blindly detect the cyclic prefix length of sidelink synchronization signals transmitted by another UE.
For a sidelink synchronization resource configuration associated with PSDCH reception, if cell c is indicated by the parameter physCellId-r12 and if the parameter discSyncWindow-r12 is configured with value w1 for cell c, the UE may assume that sidelink synchronization signals are transmitted in cell c and that they are received within a reference synchronization window of size +/-w1 ms with respect to the sidelink synchronization resource of cell c indicated by higher layers. The sidelink synchronization identity associated with the sidelink synchronization resource is indicated by higher layers.
For PSDCH reception, if cell c is indicated by the parameter physCellId-r12 and if the parameter discSyncWindow-r12 is configured with value w2 for cell c, the UE may assume that PSDCH of UE in cell c is received within a reference synchronization window of size +/-w2 ms with respect to the discovery resource of cell c indicated by higher layers.
The UE transmit power of primary sidelink synchronization signal 
and the UE transmit power of secondary synchronization signal 
are given by
– If the UE is configured with sidelink transmission mode 1, and if the UE transmits sidelink synchronization signals in PSCCH period i, and if the TPC command field in the configured sidelink grant (described in [8]) for the PSCCH period i is set to 0
– 
– 
– otherwise
– 
[dBm] ,
– 
[dBm] ,
where 
and 
are defined in [6]. 
and 
where
is defined in Clause 5.1.1.1. 
and 
are provided by higher layer parameters associated with the corresponding sidelink synchronization signal resource configuration.
If sidelink synchronization signals are transmitted for PSDCH, and if the PSDCH transmission does not occur on any serving cell configured for the UE, 
is the cell indicated by higher layers on downlink carrier frequency indicated by discCarrierRef [11]. Otherwise, 
is the serving cell on which the sidelink synchronization signals are transmitted. If sidelink synchronization signals are transmitted for PSDCH, then PSDCH and sidelink synchronization signal transmission occur on the same carrier frequency.