Transmission Performance Analysis Of Non-Orthogonal Multiple Access System Based On Short Packet Communication

The popularity of the fifth-generation(5G)mobile communication technology and the Internet of things(Io T)leads to the large-scale access of terminal equipment and the rapid increase of data services.Traditional communication techniques have been unable to meet the requirements of high speed,low delay,and high reliability,which has brought huge challenges to the development of wireless communication.As a promising technology,short packet communication(SPC)can effectively reduce the system transmission delay in the form of short data packet transmission and plays an important role in the scenarios of massive machine-type communications(m MTC)and ultra-reliable and low-latency communications(u RLLC),which has become one of the key technologies of beyond 5G(B5G)and future mobile communication network.In addition,non-orthogonal multiple access(NOMA)technology can effectively solve the current shortage of mobile network spectrum resources and significantly improve the system spectrum efficiency.In recent years,it has gradually attracted the attention of academia and industries.Therefore,this paper takes the SPC-based NOMA communication system in the Io T scenario as the main research object and analyzes the performance of the system from two perspectives.The details are as follows:(1)First,this paper studies the uplink transmission performance of a two-user NOMA system based on SPC.Taking the average throughput of each user at the base station as the performance index,under the constraint of fixed power allocation,the closed expression of the average transmission error probability of each user is derived,and then the calculation of average throughput of users is obtained.On this basis,the internal relationship between the amount of transmitted information,packet length,user transmission power,and user average throughput is analyzed through experimental simulation.An uplink transmission performance of orthogonal multiple access(OMA)two-user system based on SPC is established as a comparison scheme.The simulation and analysis results show that compared with the uplink of the OMA two-user system,the NOMA scheme combined with SPC can effectively improve the transmission performance of two users in the system and achieve higher throughput than the traditional OMA scheme.(2)Then,this paper studies the downlink physical layer security(PLS)transmission performance of a two-user NOMA system based on SPC,and builds a system model with an eavesdropper.Aiming at maximizing the security throughput of the weak user,a problem of maximizing the security throughput of the weak user is established under the conditions of meeting the total power constraints of base stations,the power allocation constraints of base stations,and the maximum transmission error probability constraints of strong users.A power allocation scheme with low computational complexity is proposed to optimize the transmission power of the base station,which maximizes the security throughput of the weak user on the basis of guaranteeing strong user performance and ensuring the transmission security of system information.The simulation and analysis results show that compared with the traditional OMA scheme,the SPC-based NOMA scheme can effectively increase the security throughput of weak users in the communication system and reduce the transmission delay.