The secondary sidelink synchronization signal (SSSS) is transmitted in the
central 62 resource elements of two adjacent SC-FDMA symbols in a synchronization subframe.
The same sequence of 62 complex values is repeated in each of the symbols, resulting in a
124-by-1 element vector returned by the lteSSSS
function. The values of this sequence are ordered as they should be
mapped into the resource elements of the adjacent symbols using lteSSSSIndices
. If a terminal is transmitting SSSS then it should be sent
every 40 ms for D2D sidelink or every 160 ms for V2X sidelink, with the exact subframe
dependent on the RCC signaled subframe number offset
(syncOffsetIndicator-r12). The SSSS is sent on antenna port 1020,
along with the primary sidelink synchronization signal (PSSS). A synchronization subframe
also contains the PSBCH, which is sent on antenna port 1010. The transmission power of the
SSSS symbols should be the same as the PSBCH therefore they should be scaled by in a subframe. No PSCCH or PSSCH transmission will occur in a sidelink
subframe configured for synchronization purposes.
As specified in TS 36.211, Section 9.7, the SSSS identity assignment
depends on the network coverage. The set of all is
divided into two sets, id_net {0, ..., 167} and id_oon {168, ...,
335}, which are used by terminals that are in-network and out-of-network
coverage, respectively. The sidelink physical layer cell identity
number, ,
corresponds to the lteSSSS
input
UE settings structure field ue
.NSLID
.
Within each set, all identities result in the same SSSS. For an in-network
terminal, the ue
.NSLID
value
corresponds to the RRC sidelink synchronization signal identity (slssid-r12)
associated with the cell.