| Massive multi-user multiple-input multiple-output?MU-MIMO?technology explores the degree of freedom by implementing large scale of antennas array,which can greatly improve the transmission rate and energy efficiency.However,the multi-user interference?MUI?will degrade the system performance.The symbol level precoding?SLP?is designed based on the channel state information and the modulated symbols,in which the MUI is converted into constructive interference?CI?.It can improve the system performance effectively.However,the SLP generally requires fully digital beamforming architectures,which contains a large number of radio frequency?RF?chains,leading to high cost and power consumption.The antenna selection?AS?technology selects part of the antennas for transmission via the switch structure while maintaining the overall system performance.Therefore,we propose a SLP and AS algorithm by eliminating the MUI and reducing the hardware complexity in this work.First,we constructed the optimization function according to the AS-SLP system objective by minimizing the Euclidean distance between the received signal and the input signal and selecting the optimal antenna subset.However,due to the non-convexity of the constraint on antenna subset,the optimization problem is NP-hard and cannot be solved directly.By approximating?0-norm into?1-norm,the underlying problem is converted to regularization problem.Furthermore,the convex optimization function is constructed by introducing variables which can solved via alternating direction method of multiplier?ADMM?,and the optimum antenna subset can be obtained by extending the algorithm from the real domain to the complex domain.Finally,the zero forcing?ZF?SLP is achieved based on the selected antenna subset.Simulation results demonstrate that the proposed design can effectively reduce the symbol error rate?SER?and improve the system performance effectively,which is more suitable for massive MU-MIMO. |
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