Abstract:

In 3G evolution systems, it’s an important inter-cell interference mitigation scheme for inter-cell interference coordination, which includes various frequency reuse methods. At the same time, the concept of available frequency sets is proposed for frequency reuse, which not only enables to mitigate inter-cell interference, but also enables to improve frequency utilization. On this basis, how to allocate the sub-carriers in available frequency sets is a critical problem, which directly relates with the strength of interference. But on the other hand, the existing methods are usually on the state of current channel, which easily causes extra interference due to time delay. In this situation, an adaptive subcarriers allocation method is proposed, which is based on the forecast by Kalman filter. In this method, the gain interference ratio (GIR) among users and available subcarriers are got by measurement. Then the GIR in the next time is forecasted by Kalman filter, and the subcarriers are allocated according to such forecasted GIR. The simulation results show that compared with fixed subcarriers allocation and subcarriers allocation based on current GIR, the proposed method can effectively reduce inter-cell interference under different frequency reuse methods, and improve the performance. Specially, the throughput is raised, and the blocking rate and the bit loss rate in cell-edge are also reduced too.

Key words: inter-cell interference (ICI), Kalman filter, subcarriers allocation, gain interference ratio (GIR)