Research On Spatial Modulation Of 5G Communication Systems

The avaliable resources for wireless communication system includes: frequency domain, time domain, code domain and spatial domain resources. However, frequency, time and code have been exploited fully, and it is difficult to further exploit. Coding, modulation and other technical research results show that these techniques have been approaching the shannon capacity, and further improving its potential is very difficult. From the aspect of information theory, Multiple-input multiple-output(MIMO) technologies could improve the channel capacity significantly than the single-input single-output(SISO) system by introducing space resources. In the future 5G systems, MIMO technology will be essential for future mobile communication system which can greatly improve the spectrum efficiency.Traditional MIMO technology actives all of the transmit antennas simultaneously to convey more information bits. Space shift keying(SSK) modulation and spatial modulation(SM) have been emerged in recent years as new MIMO techniques. Compared with traditional MIMO technology, the difference between SSK, SM and traditional MIMO is that SSK and SM technology use the index of transmit antenna to convey part of data information, where traditional MIMO use APM(Amplitude/Phase Modulation) modulated symbols to convey all the data information. Different with traditional MIMO technology, these new technologies active only one or several antannas in each transmission and thus the radio frequency(RF) chain is reduced significantly. Therefore, the interchannel interference and the synchronization problem between multiple receive antenans are avoided. The new technology is especially suitable for the antenna unbalanced system, such as the massive MIMO system where the base station has massive transmit antennas but the user equipment has few receive antenas. But as a new technology of MIMO, SSK and SM both have the disadvantage of low spectrum efficiency and low utilization of the transmit antennas.This thesis has done a lot of work considering the disadvantage of low spectrum efficiency and low utilization of transmit antennas of SSK and SM, and two improved SSK technologies with high spectrum efficiency are proposed in this thesis: layered space shift keying(LSSK) modulation technology and multiple stream space shift keying(MSSK) modulation technology. These two methods both divide the data into multiple layers or multiple streams and modulate them on the transmit antennas simultaneously. The problem of multi-signal collision is avoided when transmitting multiple data streams in conventional SSK or SM system through the proposed LSSK and MSSK modulation schemes. The proposed LSSK and MSSK techniques both improve the spectrum efficiency of traditional SSK and SM technology significantly by transmitting multiple data streams simultaneously.The theoretical and simulation results are both given in this thesis. Simulation results show that LSSK and MSSK have the advantage of high spectrum efficiency and better bit error rate performance than some conventional schemes.The conventional antenna selection technique in spatial modulation system has the weakness in complexity and performance. We proposed an antenn selection based precoding scheme in SSK and SM system to improve the performance and reduce the computational complexity. The proposed scheme not only reduces the complexity of traditional antenna selection algorithm in SM system but also improves the performance of bit error rate of conventional SSK and SM technologies. We also extend the scheme to multi-user communication system and propose a feasible scheme as downlink multiple access technique in spatial modulation system. The proposed scheme in downlink multi-user system can eliminate multi-users interference of spatial modulation system through precoding on the transmitter and improves the performance through antenna selection algorithm.