Research On Fast Interference Coordination Scheme Based On Wavelet Transform

With the explosive growth in the number of communication devices and their traffic demands,the system spectrum efficiency of cellular networks must be increased to meet the increasing traffic demands of terminals and better terminal experiences.Spectrum scarcity has always been a key problem in wireless mobile communications,and due to recent development of wireless mobile communications,the problem of spectrum scarcity has become more serious.Frequency reuse technology allows devices in adjacent cells to simultaneously transmit data in the same frequency band,which significantly increases spectrum utilization,but also introduces inter-cell interference and limits the spectral efficiency of the system.Dynamic interference coordination is deeply studied because of its high flexibility,rapid response,and obvious coordination effect.It reduces the mutual interference between cells by scheduling resource blocks in the cell,thereby improving the spectrum efficiency of the system.In the future dense terminal network scenario,the traditional dynamic interference coordination optimization scheme has a high time complexity and a long operation time,which is not applicable in actual scenarios.Therefore,it is especially necessary to find a fast interference coordination scheme.This dissertation mainly studies the interference coordination problem in ultra-dense network scenarios.For two-cell scenarios,fast interference coordination schemes for single-cell performance optimization and two-cell performance optimization are proposed.According to our experience,the interference coordination time is too long in ultra-dense network scenarios when the scale of the coordination problem is large.The single-cell performance optimization fast interference coordination scheme mainly reduces the problem scale hence reduces the coordination time cost.The terminals in each cell are first sorted to increase the redundancies of useful signals and interference parameters.Then,the parameters are transformed into wavelet domain by discrete wavelet transform,and the low-frequency information is extracted from the wavelet-transformed signal,while only scale coefficients are retained.After this step,the length of the original signal is reduced,thereby reducing the problem scale.Finally,interference coordination is completed in wavelet domain,and the obtained coordination strategy is converted back to the original domain by discrete wavelet inverse transform,and the final interference coordination strategy is obtained by an inter-domain conversion.In addition,we have further studies the fast interference coordination scheme for performance optimization of two cells,which mainly proposes a grouping and sorting method.First,terminals are sorted according to the useful signal values,then terminals are grouped and sorted so that the interference values of the terminals in adjacent groups alternately appears in descending order and descending order.This method simultaneously increases the redundancies of the useful signals and interferences,so that the scheme can optimize the performance of two cells.Coordination results obtained by these schemes are compared with the optimal coordination strategy obtained by the Hungarian algorithm,demonstrating that the proposed schemes reduce the time cost while keeping other performance metrics still close to the optima.