Research On New Technologies Of Signal Space Diversity

In wireless communication systems, channel fading is one of the great challenges to transmission rate improvement and system reliability. In order to combat fading effects, Signal Space Diversity (SSD) technique is invented. In this thesis, in-depth researches are conducted concentrated in this key technique and its application in traditional BICM systems, OFDM systems and relay networks. The goal is to enable this bandwidth-efficient technology to properly combine with techniques such as channel coding, spatical diversity, time diversity and path diversity to aid different fading senarios. The system performance should be improved in this way.The contribution of this thesis is concluded as follow. Firstly, we conduted detailed analysis and research on Joint Coding Moduation Diveristy (JCMD) system, which is based on Signal Space Diversity. We found that by applying constellation phase rotation to tranditional BICM signal and including corresponding component interleaver, the system’s fading-resisting ability is significantly improved. Then the BICM-ID system is further modified by effective constellation map and soft information iteration. The study proved that SSD signal can better exploit the extrinsic information and attain relative advantage against BICM-ID scheme.Besides, because of the expansion of tranditional QAM signal, every single component of a constellation point is blessed with the ability to present one or a set of symbols. According to this principle, the resulted component demodulation enables relays to recover the complete message by overhearing only an incomplete transmission from the source. This research further exploited the idea, extended SSD to cooperation communications and obtained efficient distributed algorithm. Finally, SSD-based JCMD system is implemented on LTE eNodeB hardware. Through the tests on system constructed from DSP devices and channel simulator, this thesis validated that Signal Space Diversity not only reveals potential in theoretical exploration, but also be able to play a role in practical systems.