| The mobile communication technology alters from day to day,users and terminal devices of the communication system are scattered all over like stars in the sky.Faced with the increasingly complex network transmission environment,it's urgent to apply effective technology to solve the problem of shortage of spectrum resources and cope with future communication network's demand for higher transmission rate,better coverage and lower transmission power.The current cellular systems mostly take the way of frequency reuse factor of 1to organize networks in order to improve the spectrum utilization efficiency.However,such reuse of frequency resources by cell and the user will inevitably bring strong inter-cell and inter-user interference,which extremely restricts the communication quality of cellular system.In addition,all kinds of new network architectures also bring new interference to the existing networks.In recent years,interference alignment(IA)as a kind of innovative coding technique to eliminate interference get more and more researchers' appreciation because of its advantage of effectively eliminating the interference in the network and improving the system transmission rate.In this paper,we mainly focus on the use of interference alignment technology in the downlink communication link of cellular systems.An interference management scheme which has wider applicability and higher system transmission rate is proposed aimed at the deficiency that among the available IA algorithms some merely suppress interference signal while ignoring the control of the useful signal,some of them although have a joint optimization of the disturbance signal and useful signal but neither require the communication channel to satisfy the reciprocity condition nor the nonlinearity of the algorithms are too high to be convergent.The main work of this paper is as follows:(1)Remodeling the user's received signal in cellular downlink communication considering inter-user interference in a cell to make a joint optimization of useful signal and all interference signals.(2)On the basis of model above,we propose a new interference alignmentalgorithm based on rank constrained inter-user and inter-cell interference matrix rank minimization(RCRM-UC)The scheme minimizes the space of the cell and user interference signal under the constraint that the useful signal occupies all available signal space to make a joint optimization of the useful signal and interference signal and takes the convex optimization method to seek for the precoding matrix and the receiver suppression matrix in the later stage of the algorithm.(3)Combined with the transmit antenna selection technology,this paper proposes an interference alignment algorithm based on norm antenna selection rank constrained inter-user and inter-cell interference matrix rank minimization(NBS-RCRM-UC)aimed at the imbalance between the number of antennas of the base stations and the number of the terminal users to further improve the system transmission rate.Firstly,all base stations select out the antennas subset with better performance to transmit data based on maximum F norm criterion,then eliminating the interference according to the RCRM-UC algorithm.(4)We carry out Monte Carlo emulation experiments of the two algorithms proposed above,and simulate the change of the system mean sum rate with the signal to noise ratio under the different antenna configurations and different transmit data flow numbers.Furthermore,we compare the rate performance of our strategies with the same type of other algorithms.The simulation results show that the proposed schemes can effectively improve the system transmission rate. |
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