In the legacy LTE network, the Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS) are transmitted once (each of them) every 5ms i.e. in subframe 0 and subframe 5 . But a pair of Primary Side link Synchronization Signal (PSSS) and a pair of Secondary Side link Synchronization Signal (SSSS) are transmitted in the sidelink synchronization subframe in case of D2D or v2x communication. But I am not clear why.
Thanks in advance.
Dear Merkebu,
welcome!
I would expect that the channel conditions D2D and V2X is more serve than the channel conditions in conventional mobile communication systems. The multipath fading and the fast fading due to doppler effect may be more pronounced in such communication channel. Which means higher rate change of the channle with time. Consequently the frequency of the synchronization signal must be increased.
Best wishes
