Abstract:

The massive multiple input multiple output technology becomes one of the key technologies of mobile systems at present and even in the future due to its high spectrum efficiency and energy efficiency.However,as the number of user antennas increases,the complexity of the detection algorithm will increase sharply,which makes the algorithm difficult to implement quickly and effectively in the actual system.An improved conjugate gradient iterative algorithm is proposed to solve the problems of high computational complexity and slow convergence.Under the condition of channel hardening,in this algorithm the initial matrix of the Richardson iterative algorithm is used as the initial matrix of the Newton iterative algorithm for one iteration,and the result of the Newton iterative algorithm is used as the initial matrix of the Conjugate Gradient iterative algorithm for further iteration.Through these steps,the algorithm not only keeps the computational complexity low,but also accelerates the convergence speed.The computational complexity of the algorithm is quantitatively analyzed by theory,and the bit error rate performance and convergence speed of the algorithm are compared with other typical detection algorithms through simulation experiments.Simulation results show that the proposed algorithm has a lower computational complexity and faster convergence speed compared with other schemes.When the modulation mode is 64QAM and the antenna size is 32×256 or 64×1 024,the detection performance is close to the minimum mean square error algorithm only after 3 iterations.

Key words: massive multiple input multiple output, signal detection, iterative algorithm, the initial matrix