Research On Relay Selection And Performance Of Multi-relay Cooperative Spatial Modulation System

The requirement in terms of speed,accuracy,and complexity for communication is increasing with the development of communication and network technology,and the traditional multi-antenna system can no longer meet the growing usage demands of people.Spatial modulation technology has become one of the hotspots for technology because it can validly lower system complexity and power consumption,and avoid problems such as synchronization and interference that traditional technologies need to consider.Wireless communication technology has also received extensive attention due to its ability to reduce transmission power and improve signal transmission quality.Both it and spatial modulation technology have been used in the new generation of mobile communication systems.Therefore,this thesis applies the spatial modulation technique to the collaborative communication scheme to form a collaborative spatial modulation system,with the objective of evaluating and optimizing the false bit rate performance of the collaborative spatial modulation system,considering the application scenarios when multiple relays are used for collaboration.Three situations were studied,namely,the optimal relay location for multi-relay forwarding,the false bit rate of the system with incomplete channel state information,and the false bit rate of the system with additional spatially correlated channels.This thesis studies and analyzes details as follows:1.A three-node collaborative relay system is considered,and a relay selection method is proposed to maximize the signal-to-noise ratio at the receiving end by applying spatial modulation techniques to the source node with the geographic location of the relay as a reference factor.The optimal relay location in the three-node collaborative relay system module is first derived as the midpoint of the link between the transmitter and receiver,then a way to select the relay is given.The moment generating function is also used to transform the analysis of the system BER into the pairwise error probability.We used simulations to verify this method's effectiveness and compared with other schemes to show the improvement of the BER performance of the method.2.For spatially modulated systems using multi-amplified forwarding relay collaboration,the effect of incomplete channel state information on the system's false bit rate is considered.By deriving the moment generation function for each transmission link,the theoretical average BER and asymptotic BER of the system are calculated.The simulation verifies that the error generated by the incomplete channel estimation will have an impact on the false bit rate of the system,and the impact of different channel estimation errors is also different.And the proposed relay selection method outperforms the random selection or circular forwarding methods when the relays are in different positions,even the channel estimation mistakes exist.3.We study the error performance for the collaborative spatial modulation system with the existence of channel estimation mistakes in the relevant channel and a power allocation scheme is proposed to optimize the BER performance of the system.Both incomplete channel estimation and correlation between individual antennas have an impact when analyzing the BER of the system.The theoretical BER and asymptotic performance of the system are derived using the signal-to-noise moment generating function in the presence of estimation errors under correlated channels.In addition,we were given a power allocation scheme with the goal of reducing the false bit rate of the system.It constructs a Lagrangian function to calculate the best power for all transmitter nodes.The simulation verifies that the proposed scheme can further optimize the system's false bit rate.