Research Of Systems Coexistence And Interference Mitigation In The Environment Of Multiple Wireless Communication Systems

With the rapid development of wireless mobile communication technology, in thesame wireless channel environment, multiple communication systems and multiplecommunication standards will be in long-term coexistence, as a result, inter-systemsinterference mitigation in the coexistence of multiple wireless communication systemsremains an important topic in the near and distant future. The systems will inevitablycause corresponding interference in a region of space, frequency band, time intervaland code section. It will seriously affect the quality of communication and rates ofdata transmission. So the research on inter-systems interference mitigation in thecoexistence of multiple wireless communication systems and standards has greattheoretical significance and practical value. In this thesis, taking the singleTD-SCDMA cell self interference system and the mutual interference system betweenTD-SCDMA and CDMA2000as study objects, the coexistence of multiple wirelesscommunication systems and standards is studied, base on which correspondinginterference mitigation strategies and power control strategies are put forward.First, in order to make the research route and technical method clearly, a newviewpoint of interference analysis is put forward. According to different subjects,different aspects and different methods, the interference analysis is derived into threeroutes. These three routes are respectively electromagnetic compatible route, networkplanning and signal processing route and stochastic geometry route.Second, taking different interference types as a main research line, the theory ofdifferent interference are discussed in corresponding chapters. The adjacent-channelinterference and co-channel interference are analyzed in chapter3by a model ofsingle TD-SCDMA cell interference in ideal power control scene. The deterministicmethod and Monte-Carlo simulation method are used to investigate the mutualinterference between TD-SCDMA and CDMA2000, respectively. From the theory andthe analysis of the simulation results, the layout and construction scheme ofinterference mitigation are suggested. Co-layer interference and cross-layerinterference that are two kinds of typical interference types in the two-tier networksare examined in detail in chapter4. Taking LTE-femtocell two-tier networks as theobject of study and taking auction theory as a research tool, Bayesian Nash equilibrium method is employed for optimal power control. Firstly, the optimal SNRthreshold can be found by using Bayesian Nash equilibrium method. Secondly, thegeneral utility function is constructed by that threshold and Nash equilibrium method.The simulation results show that the iteration numbers can be greatly reduced, thepower control time can be shortened, and the optimal control and co-layer interferencemitigation as well as cross-layer interference mitigation cab be achieved by usingproposed power control scheme.Finally, from the viewpoint of information theory, achievable rates of twointerference channels are studied in this thesis. Pareto optimality is applied to twocoupling interference channels to allocate transmission power. The results show thatwhen the system is in the Pareto optimality, using the minimum transmission powercan reach the maximum channel rate. In addition, achievable rates are equal in eachchannel and it is only related to the channel parameters in the state of Paretooptimality. Furthermore, it provides a theoretical tool to avoid using too muchcomplex interference mitigation method for achieving maximum rate of the channel.