Interference And Capacity Analysis In The New Generation Mobile Communication Systems

The rapid development of mobile Internet leads to an increasing demand formobile data bandwidth, brings unprecedented amount of pressure to the capacity ofmobile communication networks, and promotes the research and application of avariety of broadband wireless communication technologies. Capacity of the mobilecommunication network is not only affected by the radio frequency and networktechnology, but also significantly influenced by the network interference. Therefore,without supplying extra resources, how to reduce the network interference and how toimprove the overall capacity of the network become the mainfocus of this thesis. Thethesis investigates interference issues of typical cross-slot reuse and frequency reusewithin the network in the new generation of TD-SCDMA, multi-hop cellular systemsand cognitive spectrum sharing systems.Specific results are as follows:First, as to the cross-slot interference in TD-SCDMA systems, we analyze theinterference to the network caused by cross-slot reuse and propose a method ofreducing interference by controlling cross-slot coverage. Based on the networkcross-slot distribution, this method dynamically adjusts the radius of the coverage ofthe cross-slot, reducing the cross-slot interference and enhancing the network capacitywithout raising the level of intra-system interference conditions.Furthermore, analysis of a joint detection algorithm in TD-SCDMA networks forco-channel interference cancellation is provided, with the focus on assessment andanalysis of the practical application of joint detection algorithm in large-scalecommercial networks, and simulation results are given and compared. The evaluationresults show that the joint detection algorithm effectively inhibits the co-channelinterference, reduces network dropped call rate, and has the full application value inthe commercial TD-SCDMA network. In addition, to enhance the network utilizationunder the same network quality, we study the relationship of the network utilizationand the network quality of the current TD-SCDMA networks, and find the finalinflection point of the network quality. To practically implement it on the networktraffic, we can achieve the maximum point of the network utilization.As to the multi-hop cellular system composed of the self-organizing network andthe cellular network, we propose the joint algorithm of the space multiplexing and smart antenna technology to effectively control the co-channel interference within thesystem, enabling cellular system and multi-hop nodes to share radio resource. Inaddition, with the use of reasonable spacing and reuse factor for a multi-hop node, ourmethod can effectively improve the multi-hop cellular system capacity.To guarantee the quality of service, improving spectrum use demands the use ofspectrum sharing scheme. In order to achieve a reasonable reuse of the spectrum, basedon non-cooperative game theory, we design the typical utility function which is relatedonly to cognitive user’s SINR threshold and the current obtained SINR, and also takesinto account the user fairness. Furthermore, we propose a power control algorithm toeffectively improve the effectiveness of spectrum sharing.