Inter - Cell Interference Coordination Based On Partial Frequency Multiplexing

With the development trend of mobile, broadband and IP in LTE network, the macro cell, microcell, picocell and femtocell are all contained in the network. The capacity and coverage of cell are not the same. Due to the existence of the co-layer interference and cross-layer interference caused by the reuse of frequency, it is need to adopt effective interference suppression scheme in order to improve the and ameliorate the quality of service for cell edge users.The method to suppress inter-cell interference was studied in this paper using fractional frequency reuse(FFR) and soft frequency reuse(SFR). All of the macro cells are divided into the central area and the edge area. Divide the system total available frequency band into N+1 and N parts according to the frequency reuse factor N, respectively. In FFR, all of the macro cell center users are assigned the same frequency band period f0. Then divided the remaining band into N parts and assigned to the macro cell edge users, ensuring that all neighboring cell-edge user use different frequency bands during the allocation process. In SFR, firstly we divide the system’s total available frequency band into N parts. Then we allocate resources for macro cell edge users at first, which also ensures that bands used by adjacent cell edge users are all different. The difference with FFR is that the macro-cell center users can use the frequency band used by neighboring cell edge users in SFR, which improved the bandwidth efficiency. When the allocation of spectrum resources to macro cell users is completed, we divide the frequency band for microcell users according to the relative location of the microcell in the macro cell. If microcell located in the macrocell center area, the bands assigned to the microcell are the same as the band used by macrocell edge users. Otherwise, if microcell located in the edge region of the macrocell, the microcell users may use the same band assigned to macrocell center users, which suppressed the inter-cell co-layer interference during macrocells and the cross-layer within macrocells and microcell at the same time.A dynamic cell edge spectrum sharing method was proposed based on the study of FFR and SFR in the LTE wireless network. The density of cell edge users in macrocell are not the same in the LTE network. We can divide the idle frequency band in macrocell edge area and share for adjacent cell edge users when the traffic of neighboring cell edge region increases in order to relieve neighboring cell’s traffic pressure. As for the concrete spectrum allocation in LTE wireless network when using FFR, an allocation algorithm was proposed based on searching the neighboring cell idle spectrum resource, which suppressed the inter-cell interference combined with carrier power allocation method.