Fast Synchronization and Cell Identification via the Overlapped Fast Fourier Transform for the 5G New Radio and V2X Communications

Abstract

Currently, the fifth generation (5G) new radio (NR) wireless system has been widely deployed due to its higher throughput, lower latency and massive machine communications abilities compared with the conventional fourth generation (4G) system. To achieve these features, 5G systems can be either operated at sub-6G frequency, or millimeter wave band for the available bandwidth resources. It is well-known that the channel attenuation degradation at millimeter wave band is more seriously than the sub-6G frequency. Therefore, to facilitate the coverage requirement, the physical cell identification (PCI) number of 5G was doubled from 4G to support the small cell architecture. Besides, a vehicle to everything (V2X) sidelink communication is also supported by 5G to achieve higher throughput and lower latency capabilities. For both the NR and V2X, the functions of cell identification and the signal synchronization are conducted via the same Primary Synchronization Signal (PSS) and the Secondary Synchronization Signal (SSS). Therefore, how to fast and accurate achieve the signal synchronization and acquire the cell identification to facilitate the low latency requirement become serious issues. In this paper, a fast signal synchronization and cell identification method is proposed via using the well-known Fast Fourier Transform (FFT). Combined with the overlapped FFT signal processing and the features of m-sequence, the required computational complexity of signal synchronization and cell identification of the proposed method can be greatly reduced more than 92% compared with the correlation-based method and can be applied directly to both NR downlink and V2X sidelink scenarios.