Distributed Cooperative Transmission Technology Based On CPM Signal

In order to expand the communication coverage and improve the reliability of communication,collaborative communication technology came into being.It takes sharing as the idea,and obtains spatial diversity gain by sharing the antennas of users with each other to transmit signals.Nowadays,collaborative communication technology is widely used in mobile ad hoc networks.However,in this scenario,terminal devices are often powered by batteries,which are limited by energy and cost,and have certain requirements for power consumption.Continuous phase modulation(CPM)due to its continuous phase and constant envelope characteristics,low-cost nonlinear power amplifiers can be used and energy consumption is small,so it is very suitable for use in conjunction with collaborative communication technology.In addition,the common methods for coordinated transmission between devices include distributed space-time coding and distributed beamforming.Although the performance is superior in mobile ad hoc networks,these two methods require too much coordination between nodes and it is difficult to obtain timely feedback among the constantly moving cooperative nodes.In this context,this paper studies the cooperative transmission technology in the mobile ad hoc network represented by barrage relay networks,and avoids the complicated coordination processing with a small performance loss.The main research contents are as follows:Firstly,the characteristics and basic principles of CPM are comprehensively explained,including the definition of the signal,the phase state of the signal,and the mode of modulation and demodulation.Then it introduces the key technology in cooperative communication,and gives the performance simulation comparison under different forwarding and merging modes.Then,the power spectral density(PSD)and channel capacity of the CPM signal are studied.Two methods for calculating the power spectral density of the CPM signal are introduced.The influence of the modulation parameters on the PSD is simulated and studied,and the channel capacity of CPM in AWGN channel and Rayleigh channel are deduced and simulated.Then,the highly reliable LDPC code is introduced,combined with the high efficiency of the CPM spectrum,the continuous phase modulation and the LDPC code are formed into a coded modulation system and the comprehensive performance of the LDPC-CPM system under different parameters is simulated in order to select the best parameters that take into account spectrum efficiency and power efficiency.Finally,this article introduces the background of barrage relay networks,and introduces its concepts and key technologies in detail.Aiming at the problem of excessive system overhead caused by multi-relay cooperation in barrage relay networks,a multirelay selection scheme based on residual energy and channel state information is proposed.By setting the weight function,the information can be transmitted normally.Under the premise,the network survival time is improved,and it is proved by simulation comparison with the traditional CSI-based relay selection method.Then,in order to reduce the coordination required for cooperative transmission between nodes in the barrage relay networks,a cooperative transmission method based on LDPC-CPM and random phase rotation is designed,and its channel capacity and performance are simulated and analyzed,which did not require too many relay coordination processes can quickly transmit messages,which is very suitable for barrage relay networks.