Research On Interference Coordination And Cell Selection Based On Power Allocation In Cellular Networks

With the rapid development of the mobile Internet and the explosive growth of data service demand,we must improve the system spectral efficiency to meet the user's increasing traffic demand and a better user experience.Static interference coordination can improve the system spectral efficiency,but it brings about serious inter-cell interference.Dynamic interference coordination is an effective method to deal with cellular interference and improve system spectral efficiency thanks to its strong flexibility.Power allocation is also a useful method of interference management in cellular networks,so combining it with dynamic interference coordination may be a promising idea,but the combination of these two techniques still needs further study.In this dissertation,we study the joint optimization of dynamic interference coordination and power allocation in cellular networks.For the uplink transmissions of a two-cell scenario,we theoretically obtain the closed-form expression of the near-optimal power allocation ratio for terminals in adjacent cells paired in the same resource block,which assigns power to the terminal according to its channel condition.Then the power allocation ratio is directly applied to the dynamic interference coordination scheme,which gives the optimal matching result.Finally the derived near-optimal power allocation ratio is applied for the scenario with seven adjacent cells.Considering that the central cell is used as the reference cell,the other cells are matched with the central cell in the same way as in the two-cell case,which gives the optimal matching result.Numerical results show that,our scheme can significantly improve user fairness and packet receiving rate,without obviously degrading the system's average spectral efficiency.Heterogeneity is a widely considered effective way to improve cellular network's coverage and system spectral efficiency.In heterogeneous cellular networks,by deploying low-power cells with traditional macrocells,i.e.,picocells and femtocells,seamless and ubiquitous access service can be provided at any time anywhere and each terminal may be covered by multiple cells.Heterogeneous cell selection has significant influence on the whole network's performance.If each terminal selects its appropriate cell to access,the best performance of the whole network may be achieved.In this dissertation,stochastic geometry is used to model densely deployed heterogeneous cells,and cell selection optimization in a two-tier heterogeneous cellular network is studied.To maximize the total utility of the system,we propose a sectorized network-side cell selection algorithm.Besides,due to the existence of shadowing in wireless channels,and the shadowing follows logarithmic normal distribution.The received power of terminal accessing a cell is random,so we theoretically obtain the probability of each terminal accessing a cell.Finally,we study the joint optimization of power allocation and cell selection,which reaches the near-optimal cell selection result.Simulation results show that the proposed scheme out-performs the traditional scheme with constant power.