Design And Study Of Constellation Of GSM System Based On Multiple Constellation Patterns

With the rapid development and maturity of the fifth-generation（5G）mobile cellular network technology,the application of 5G in the field of intelligent driving will become a research hotspot.The openness of wireless transmission and the mobility of vehicles are bottlenecks in the application of internet of vehicles.In view of this situation,the combination of vehicle-mounted network and 5G technology will provide strong technical support for traffic and road management and improving user experience.However,in the process of vehicle-mounted network communication,massive data will be transmitted,so a novel network architecture is needed to support big data transmission scenarios.Massive multiple input multiple output（Massive MIMO）,one of the multiple antenna technologies,makes full use of all antennas to simultaneously transmit independent or related information to obtain multiplexing and diversity gain.It has become one of the powerful technologies to solve the problem of bit data transmission.However,due to the simultaneous active state of multiple antennas and the time-varying of the channel,it inevitably brings some problems such as interantenna interference,increased deployment cost and poor performance.But,the transmission rate of spatial modulation（SM）is too low.In order to improve the transmission rate of the system and avoid the deterioration of system performance,researchers increase the number of activated antennas and select non-adjacent antennas to transmit information,so as to improve the transmission rate as much as possible on the premise of less loss of performance.This is generalized spatial modulation（GSM）.This paper takes the GSM system as the research object,focusing on how to modify the GSM system to improve the transmission rate and how to improve the performance of the GSM system after the modification to carry out reliable data transmission.The main work and innovations are as follows:1.To solve the problem of low transmission rate of GSM system with diversity gain,a dual constellation mode GSM（DM-GSM）system is proposed.In the GSM system,where the antennas are activated to transmit the same information,the problem of low transmission rate of the system will be caused.In response to the above problems,this article proposes dual constellation mode GSM（DM-GSM）system.DM-GSM is different from GSM in that it uses all antennas to transmit information.Compared with the multiple-input multiple-output（MIMO）system,DM-GSM uses different power constellation patterns at the transmitter to correspond to different antenna combinations.Therefore,the system uses the power index to detect antennas at the receiving end.The combination index further improves the performance of the system to achieve the combination of GSM and MIMO technology.2.Based on the DM-GSM system,a GSM system based on multiple constellation modes（MM-GSM）is proposed.The main difference between this system and the DM-GSM system is that the transmitter uses more constellation patterns.Although the MM-GSM system uses multiple constellation modes to increase the invisible bits carried by the antenna combination during transmission,due to the limitation of the total power of the system,it is necessary to allocate the power of multiple constellation modes reasonably.3.Aiming at the problem of difficulty in detection at the receiving end and deterioration of system performance caused by the excessively complex work of the transmitting end in the MM-GSM system,this paper proposes an antenna combination selection algorithm.This algorithm comprehensively considers the correlation between the channels and the channel gain,and optimizes the antenna combination allocation under the relevant channel to correspond to the multiple constellation modes of the MM-GSM system.When the bit error rate（BER）is 10^-3and the spectrum efficiency is same,compared with the GSM system of proposed antenna combination algorithm,GSM system with random antenna combination algorithm and GSM system using antenna combination algorithm,MM-GSM using proposed antenna combination algorithm can get channel gain about 1d B,2d B and 1.3db respectively.4.Aiming at the problem that the more constellation modes at the transmitting end of the MM-GSM system due to the limitation of the total power,the less obvious the difference between the constellation modes,resulting in poor performance of the MM-GSM system,this article proposes an application constellation diagram for MM-GSM system.The constellation diagram of the system is a ring structure,which can maximize the Euclidean distance between constellation points.At the same time,the initial phase difference of the constellation points is increased between different constellation modes,which is not only distinguished by the amplitude of the constellation diagram,but also increases the difference between multiple constellation modes.When BER is 10^-4,the MM-GSM system with optimized multiple constellation modes will obtain a channel gain of about 1.8d B compared to the MM-GSM system with traditional multiple constellation modes.