Analysis On Spatial Modulation Based Orbital Angular Momentum Wireless Communication Systems

With the gradual puparlization of mobile electronic devices,such as mobile phones,mobile communication systems have already evolved from only needing to provide low-rate voice services into needing to provide high-rate and high-quality services,such as video services,etc.Furthermore,the fifth generation mobile communication system(5G)is in intense deployment and experimentation currently,and products supporting 5G,such as mobile phones,are being released one after another.In the future,more and more smart wearable devices will also be widely used in people's lives as mobile communication networks evolve.However,the avaliable resources for wireless communication systems,such as the frequency domain,time domain and spatial domain resources have been exploited fully.It is difficult to further exploit based on above resources.Therefore,increasing the capacity of wireless communication systems is a key issue that needs to be solved for future wireless communication systems.Orbital angular momentum waves,because of its spiral wavefront,its theoretically infinite state and natural orthogonality between different OAM states,have received a lot of attention and have been applied to the field of wireless communications in recent years.It may be a potential technology to provide a new degree of freedom for wireless communication systems and to obviously increase the capacity of commuicaiton systems.In this paper,based on the basic principle of orbital angular momentum,the unique energy spatial distribution characteristics of wireless OAM waves and the orthogonality between different OAM states are illustrated.Besides,the research status of OAM wireless communication systems is analysed.Then,combining wireless OAM waves with mutilple-input multiple-output system(MIMO)and using the energy spatial distribution characterstics of wireless OAM waves cleverly,an OAM-MIMO system is propsed.Based on the OAM-MIMO system model,the channel of wireless OAM communication system is modeled.Numerical simulations prove that the characteristics of wireless OAM channel and the utilization of OAM waves contributes to the improvement of the capacity of wireless communication systems.Besides,combining wireless OAM wave with generalised spatial modulation(GSM)technology,a new GSM communication system based OAM,namely OAM-GSM system is proposed.Numerical simulations demonstrate the capacity of OAM-GSM system is higher than the capacity of conventional GSM communication system.The channel model of OAM wireless communication system proposed in this paper has some guiding significance for the application of OAM waves.Meanwhile,based on the channel model of OAM wireless communication system,two novel wireless communication systems including OAM-MIMO system and OAM-GSM system are proposed and these two systems open up a new research idea for applying OAM to wireless communication field.