Research On Downlink Interference Suppression Strategy In Heterogeneous Networks

With the sharp development of computer technology and the increasing requirements of human beings for communication networks,the wireless mobile communication networks are also changing with each passing day.In the wireless heterogeneous network communication system,the service area of macro base stations are often accompanied by the random distribution of the low-power small base stations.While these small base stations bring a large number of users,they also overload the number of macro users of macro base stations and gradually aggravate the interference of edge users by adjacent micro areas,resulting in the reduction of the communication service quality of the whole cell.The existing power allocation algorithms mainly consider how to improve the spectrum efficiency,throughput and how to ensure the quality of service of a single service.They do not consider meeting the transmission rate requirements of users and reducing the interference of users as much as possible.Therefore,there is no way to ensure whether the actual transmission rate of users can reach the expected transmission rate of users and whether the interference problem in the system can be improved.Therefore,in the heterogeneous networks,how to reduce the interference of users,improve the signal-to-interference noise ratio of users and meet the transmission rate of users’ needs has become very important.That is,designing a practical interference suppression strategy is one of the key technologies of the heterogeneous networks.In view of the above problems,the research contents of this dissertation are as follows:(1)Aiming at the scenario of two-tier wireless heterogeneous networks,the method of combining the particle swarm optimization algorithm with the dynamic cell range expansion offset selection technology is used in the research of interference suppression in the downlink of the heterogeneous networks.Considering the actual performance requirements of base stations and users with different coverage in the heterogeneous networks,the complex interference suppression in the downlink of heterogeneous networks is studied.Combined with the particle swarm optimization algorithm and the cell range expansion technology,the micro cell service area is dynamically adjusted to find the optimal offset value of cell range expansion,in order to decrease the load pressure in the dense area of the macro base station and improve the average data transmission rate of system users,and solve the interference of users..The results demonstrate that the number of macro base station users,who use the dynamic cell range expansion bias selected,declined by nearly 10%,that is,uninstalling some macro users to access the micro base station reaching the effect of unloading macro users for the macro base station.And the SINR of the micro-cell edge user has increased by about 2 d B.The average transmission rate of system users is improved in order to reducing interference for users.(2)For the two-tier heterogeneous cellular network of microcell-femtocell covered by the multiple macro base stations,with the rapid development of multi services,the proportion of real-time multimedia services in mobile communication services is increasing.Through the research on power allocation methods,the performance of system users is improved and the interference of users is reduced.Considering both the power allocation and the interference suppression to meet the user’s expected rate,an expected rate proportional allocation algorithm is proposed.The proposed algorithm is a proportional allocation algorithm,that is,the ratio of the required transmission rate of a user to the total required transmission rate of the base station to determine the transmission power of the base station to the user,so as to minimize the waste of bandwidth resources,meet the user’s transmission rate requirements and reduce the interference to the user.The simulation results show that the proposed algorithm has good convergence,which not only improves the system transmission rate,but also improves the average signal-to-interference noise ratio of users,indirectly reduces the interference of system,and improves the service quality of the whole cell.