Research On Cross Link Interference Suppression In Dynamic TDD Networks

The dynamic time division duplex technology allows each base station to set the uplink and downlink time slot ratio according to its own actual uplink and downlink traffic conditions,instead of using the uplink and downlink time slot ratio obtained from the average traffic statistics.This,to a certain extent,solves the problem that the uplink and downlink time slot ratio set in the static time division duplex network does not match the actual required uplink and downlink time slot ratio.However,because the uplink and downlink time slot ratios of each cell using the dynamic time division duplex technology are not necessarily the same,a new interference that does not appear in the static time division duplex network appears in the dynamic time division duplex network—cross link interference.That is,the interference from the downlink station to the uplink station,and the interference from the uplink user to the downlink user.Thesis conducts research on cross-link interference suppression,and the main work is as follows:1.A cross link interference suppression algorithm based on group sparsity is proposed.The principle of the algorithm is to make the downlink station and uplink station use different subcarriers,and through sparse optimization,the number of subcarriers used by the downlink station is minimized when the performance loss of the downlink station is limited.Simulation results show that the algorithm can completely suppress cross link interference.2.A cross link interference suppression algorithm based on downlink interference sorting is proposed.The algorithm realizes the pre-classification of the downlink stations through the ranking of the maximum interference.The downlink stations that cause strong interference to the uplink stations are classified into one category,and the downlink stations that cause weak interference to the uplink stations are classified into another category.Spectrum compression is only performed on downlink stations with strong interference,thereby reducing the number of subcarriers assigned to downlink stations,and increasing the number of subcarriers available to uplink stations.Simulation results show that the algorithm increases the number of subcarriers available to the uplink station while suppressing cross link interference.Combining the downlink interference sorting operation with group sparseness and clustering,a cross link interference suppression algorithm that integrates clustering and group sparseness is obtained.The algorithm suppresses the cross link interference by clustering the base stations and spectrum segmentation based on downlink interference sorting and group sparseness.The simulation results show that the algorithm can reduce the average interference received by the uplink station from the downlink station by 99.51%.3.A cross link interference suppression algorithm based on maximizing the channel capacity of the downlink station is proposed.The principle of the algorithm is to maximize the channel capacity of the downlink station when the number of subcarriers available to the downlink station is limited.Simulation results show that the algorithm can suppress cross-link interference and control the number of subcarriers assigned to the downlink station more accurately.