A frequency allocation strategy combined with subcarrier and power allocation scheme in two-layer Femtocell-Macrocell networks

Embedding Femtocells in a Macro cellular network is a breakthrough to the traditional network, which can improve the spectral utility greatly. However, in two-layer Femtocell-Macrocell networks, exclusive channel assignment can avoid Co-Channel Interference (CCI), but the Frequency utilization rate is very low; common channel assignment can improve the frequency utilization rate but exacerbating the inter-layer interference. This paper presents a frequency assignment based on multiuser subcarrier and power allocation scheme in two-layer in two-layer Femtocell-Macrocell networks, which divide the cell into inner region and outer region by setting coverage area (FCA) threshold of a co-channel Femtocell base station (FBS), to reduce the interference between the layers through allocating different frequency to inter region and outer region. To further enhance performance of the mobile station served by MBS (MMS) in outer region, allocating subcarrier and power for MMSs within the cell, MMSs of the outer region have preference to gain better subcarriers, combined with WSA algorithm to maximize throughput; in power allocation, a hybrid power allocation is adopted for MMSs. Simulation results show that the proposed algorithm reduces the inter-layer interference and improves system throughput.