Research On Interference Mitigation Based On Resource Allocation In High-Density802.11Ac Networks

As2.4GHz frequency band has become so crowded that the new generation WLAN protocol IEEE802.1lac is shifting to the wider5GHz band. With more and more terminals supporting the WLAN technique, the customer and business demand is growing rapidly. Meanwhile, the rapid development of mobile Internet services urgently needs WLAN network streaming3G/4G mobile Internet network to carry the data traffic pressure. Besides, on college campuses, companies, families and other public or private places, users can also set up AP points according to their needs. This leads to the WLAN deployed in a high-density environment in the future, causing serious Overlapping BSS interference problem, which will bring bad impact on the network throughput and user communication quality. Furthermore, the most notable feature of802.11ac is the extended bandwidth of the wireless channels, which will lead to more prevalent overlapping BSS problem. Thus, for high-density deployed WLAN networks based on802.11ac, how to mitigate the overlapping interference between BSS by interference management is a very important issue.Meanwhile, for the limited frequency resources, in high-dense deployment network environment, the utilization of the frequency band and the overlapping channel interference is contradictory. The frequency reuse factor is higher, the smaller the overlapping channel interference, but the spectral efficiency will be low, and vice versa. Taking the characteristics of high-density802.11ac network system into account, we introduce the conception of cell division and fractional frequency reuse, research the performance of downlink interference management mechanism based on fractional frequency reuse (FFR) in the objective network environment.For the downlink interference in high-density802.11ac network, this paper presents a detailed model of the objective network based on the network scenarios and related parameters suggested by the IEEE HEW Study Group, and the interference model is formulated. We propose two interference management schemes called w-FFR-I and w-FFR-II respectively in the objective network environment based on the idea of FFR and introduce the implementation algorithms. Through the MATLAB simulation, we compare the two proposed mechanisms with the reuse-1and reuse-3schemes in frequency utilization efficiency, user performance and cell throughput. Two w-FFR schemes reach an excellent trade-off between throughput and frequency efficiency in simulation, comparing with the reuse-1and reuse-3scheme.Moreover, according to the characteristics of w-FFR-I scheme, to ensure the fairness between users, this paper also presents a dynamic channel cutting and allocating methods. When conducting channel cutting and allocation in fixed way, we compare the influence on cell-center and cell-edge user performance with the change of the cell division threshold respectively in w-FFR-I and w-FFR-II schemes. In addition, in the w-FFR-I scheme, the user performance in fixed and dynamic channel cutting method are compared and analyzed. According to the cell division threshold adopted by the network system or some certain need in actual situation, the analysis of the obtained results in this paper can be used as reference to select channel cutting and allocation method.