Abstract:

Massive random access is one of the three major application scenarios of 5G. In this scenario, pilot sequences supporting a large number of users need to be constructed, and low-complexity detection algorithms should be designed. In this paper, some deterministic low correlation sequence sets are used as the pilot sequence set. The low complexity detection algorithm is realized by using the cyclic structure of the pilot sequence set and the discretefast Fourier transform (FFT).Research shows that, compared with the traditional random pilot sequence, the pilot sequence proposed in this paper has the advantages of simple implementation and small storage space. Furthermore, the block fast Fourier transform can greatly reduce the matrix multiplication operation and accelerate the detection speed for active users. Simulation results imply that the deterministic pilot sequence set constructed in this paper performs better than the gaussian random sequence set of the same size.

Key words: random access, pilot sequence set, approximate message passing algorithm, fast Fourier transform, device activity detection and channel estimation