Semidefinite Relaxation Based Uplink Signal Reconstruction in Uplink Massive MIMO Systems

In this paper, we consider a single group massive MIMO system, which consists of one receiver (base station) deployed with large number of antennas and multiple users with each having single antenna. In the uplink transmissions from users to base station, we focus on the efficient signal reconstruction of all the users' transmitted symbols at receiver without any channel state information (CSI) estimation procedures in advance. To achieve this objective, a statistic decision matrix is firstly built based on the received signals, whose eigenvectors and eigenvalues constitute the key components of our signal reconstruction algorithm without using CSI. Then, an optimization problem is refined to reconstruct one user's transmitted signals. We convert this problem to obtaining the optimal weights by solving Semidefinite Relexation (SDR) optimization subproblem and obtaining the optimal rotation phases. Finally, the iterative algorithm framework is proposed for multi-user signal reconstruction. Numerical results are finally carried out to reveal a competitive reconstruction bit-error-ratio (BER) performance compared with the noncoherent transmission schemes and the channel-estimation-based coherent signal detection schemes.