Pre-coding Processing In Spatial Modulation System

As a novel multiple-input multiple-output(MIMO)transmission technology,Spatial Modulation(SM)technology has received extensive attention since its introduction.In addition to using traditional modulation symbols as a carrier for transmitting information,spatial modulation additionally uses the antenna index.It effectively simplify the MIMO system interference between the antennas,RF expense and other synchronization problems.In order to make spatial modulation used better in practice,pre-coding has been a hot topic.This paper focuses on the pre-coding of spatial modulation systems.First,we considered a two-point communication system.Since SSK is a special form of spatial modulation,we only use SSK at the receiver.In order to harvest more energy while correctly decoding information,a beamforming scheme has been designed at the transmitter.Since the proposed problem is a non-convex problem that is difficult to solve,two sub-optimal optimization solutions are given.One is to maximize the harvested energy and the other is to maximize the correct detection probability.Second,based on the MIMO eavesdropping model,pre-coding spatial modulation has been used.In order to improve security performance of the system,two situations have been considered.1)When the eavesdropper is active,the pre-coding matrix is designed to maximize the power received at Bob while simultaneously minimizing the power received at Eve.2)When the eavesdropper is under passive,we proposed a disturbance pre-coding design scheme that the pre-coding matrix is time-varying.Finally,we proposed a new antenna symbol mapping method.Using this method,the detection of antenna symbol at the Eve can be effectively suppressed.At the same time,we proposed a power allocation scheme to maximize the security rate of the system.