A Pseudo-Random Subchannel Selection scheme for downlink interference mitigation in two-tier cellular networks

Femtocell technology, which is adopted in broadband communication systems, has become an economical way to improve cellular coverage and system capacity. However, it is difficult to exploit the advantages of femtocells in two-tier OFDMA networks because of the interference among the macrocell and femtocells. In this paper, a Pseudo-Random Subchannel Selection (PRSS) scheme is proposed with hybrid frequency allocation for downlink transmission to mitigate the interference. Firstly, the PRSS scheme is performed to randomize the cross-tier interference by aggressor femtocells selecting subchannels pseudo-randomly. Then the proposed scheme utilizes Neighbor Relation Matrix, which could be simplified as the neighbor relationships of adjacent femtocells, to mitigate the co-tier interference. The simulation results showed that the PRSS scheme keeps interference lower while obtains better throughput compared to co-channel frequency allocation (CFA), dedicated frequency allocation (DFA), partial frequency allocation (PFA) and stochastic subchannel allocation (SSA).