Research Of Cellular Colaborative Comunications And The Relative Techniques

With the continuous development of wireless communication systems, the new requirements for the user throughput, up-downlink transmission rate, system coverage and QoS needs in cellular communication system are proposed.There are several new techniques such as frequency aggregation technique, MIMO technique, collaboration communication technique are continuously being developed into modern communications systems to meet the new requirements.Collaborative communication technique fully utilizes the omni-directional characteristics of radio waves,through the virtual and quasi-parallel distributed MIMO links, achieves spatial diversity gain and improves the system throughput. Meanwhile, the cooperative communication nodes'deployment is flexible, which can expand the system coverage region, provide signal coverage services for the serious shadowing areas and the signal blind area, and meet the system requirements of the local hot spots to enhance the robustness of the communication system. Based on the traditional cellular structure, the development and research of cooperative communication are undergoing.In this paper, based on the cooperative transmission embedded in cellular system, the collaboration communication theoretical performance, system resource allocation and adaptive MAC, cellular user collaboration communications network system evaluation were studied.Main researches and innovations summarized as follows:Cellular network deployment structure changes from the traditional model to a broader category, including two typical patterns:one is a multi-hop cellular network, which allowing the mobile terminal multi-hop transmission, expanding the system transmission links, while the other is multi-BS joint decoding cellular network, which allowing collaboration between different base stations to finish the uplink decoder/downlink equalization and get the macro diversity gain.However, the performance of joint collaboration between base stations collaboration and the user's cooperation is still to be studied. This paper studies the per-cell achievable uplink sum-rate and minimum Eb/N0 of hybrid cooperative method and the interplay between the two collaborations in single link and MIMO channels under a linear cellular model.A computational method for the achievable rate and closed-form expression of minimum Eb/N0 of AF and DF combine with multi-cell processing is derived. Moreover, the simulation results in fading channels are presented, and the results show that the macro-diversity gain from multi-BS decoding is independent with MTs collaboration but can be linear superposition, and hybrid collaboration significantly improve the system performance.However, high interference from adjacent cells weakens effect of MTs cooperation in hybrid collaboration system.In time division cellular collaborative networks, the physical frame of transmission data is allocated in time slot. However, due to the dynamics of the network accession and the multivariate heterogeneous services,fixed assignment mode of the physical frame is not optimal in resource utilization. Therefore, this paper study and resolve when and how to allocate the up-down link time resource in TDD OFDMA wireless network. Between the traditional cellular networks and mesh structure cellular network, according to dynamics of the uplink and downlink heterogeneous services,the dynamic non-symmetric proportion uplink-downlink resources allocation algorithm was proposed based on the basic user capacity access control.Numerical simulation shows that performance in resource utilization of the dynamic resource allocation algorithm is superior to the scheme of fixed proportion resource allocation.Adaptive techniques in physical layer has been extensive applied in wireless communication systems, adaptive MAC packet technique based on cross-layer design can also improve system resource utilization.According to the dynamic system transmission channel, APS_MRU method based on the channel aware and adaptive data packet size that maximized resource utility was proposed through analyzing and constructing the practical Markov channel model,which in other words is new ARQ protocol integrated physical layer adaptive modem and MAC layer frame.And the closed form solution of adaptive packet length has been also derived.Simulation results show that the dynamic packet size algorithm according to time-varying channel and modulation coding mode improves the data transmission rate and resource utilization in each round.Cellular cooperative transmission system performance evaluation is also need to be studied. The new generation wireless communications systems focus more on the performance of the worst service users.Therefore, the performance of cellular collaborative network systems after utilizing different frequency reuse factor is necessary. Around the collaboration SFR location, through investigating these two properties of per sub-carrier achievable transmission rate and the base station transmit power with SFR cooperative users in the traditional cellular network using statistical average, the inevitable result of SFR cooperative users enhance system performance was shown compare to the traditional cellular networks.In the simulation, the relation between the system BER, base station transmission power, the user deploying density, service range of SFR collaborative users and the system transmission rate were verified and compared.Also the relations between base station transmission power and BER, system requiring transmission rate, service range of SFR collaborative users is verified.