The Design Of The Transmitting Scheme In Novel Multiple Access

With the continuous development of wireless communication technology,high-speed data services and ubiquitous access requirements are showing an explosive growth,the fifth-generation(5G)of mobile communications has been proposed and developed.Novel multiple access(NMA)is one of the key technologies of 5G,which uses the non-orthogonal multi-user superposition transmission and the advanced detection algorithm,achieving a great improvement in terms of the spectral efficiency and user connections.In order to better realize the superposition of the user signal,it is necessary to design the transmitter scheme.At the same time,the energy efficiency(EE)has aroused more attention recently.Through previous research and study,this paper will focus on the EE of the NMA combined with multiple-input multiple-output(MIMO)technology,and the emphasis on the user pairing scheme and power allocation scheme.In the previous research,the base station(BS)needs to know the channel state information of all users.And also,the BS should deal with the information centrally to get the relevant pairing scheme.In order to reduce the complexity of the system,this paper puts forward a new user pairing scheme which is based on the guidance of signal space alignment(SSA).Firstly,propose the user pairing scheme based on the SSA.In the scheme,users can calculate the match parameter independently according to the reference signal space broadcasted by BS.Then,BS decides the user pairing results through the relevant matching information.Moreover,to avoid the influence of the reference signal space,this paper presents an improved user pairing scheme based on Max Collinearity,by selecting the users with the greatest collinearity.Finally,the simulation verification is performed in the downlink scenario.Simulation results show that the proposed user pairing scheme can not only improve the energy efficiency,but also increase the transmission rate of the user when the transmission power of the BS is small.In the NMA scenario,most of the power allocation schemes adopt the maximum SE to be the objective function,and there is little research on maximizing EE,especially in the uplink.Hence,the power allocation scheme in both uplink and downlink based on EE is proposed in this paper.First of all,we found that the original objective function which maximizes the system is not a concave function,and the optimal solution needs some design in order to maximize the system EE.On this basis,in the uplink and downlink,this paper utilizes the sequential convex approximation method to obtain the power allocation scheme.Finally,the simulation results show that,in the uplink,the proposed power allocation scheme can achieve more obvious performance improvement compared with the traditional partial transmission power allocation scheme.And more users,better performance.In the downlink,the proposed solution can significantly improve EE and rate.