On the performance of multiple region reverse frequency allocation scheme in a single cell downlink heterogeneous networks

The need for small-sized and low-powered home base stations such as femtocells has increased with an escalated data demand. Since the downlink traffic is larger in magnitude than the uplink, use of femtocells provides a good solution. Femto-cells not only increase the throughput but also the overall capacity of the system while operating in the same licensed spectrum. Because of their operation in the same spectrum, interference becomes a major problem. In this paper, we study the downlink performance of a heterogeneous network by proposing a Reverse frequency allocation (RFA) scheme by dividing the cell service area into multiple regions and assign frequencies to various cell entities in such a way that the major interference is avoided. RFA scheme not only improves the spectral efficiency by utilizing the complete spectrum within one cell but also eliminates the strong interference due to macro base station on femto users.We analyze and evaluate the achievable performance of this technique for the downlink scenario. Using simulations, we show that under reasonable signal-to-interference plus noise ratio (SINR) values, multiple regions enhance the performance of users by decreasing the overall system outage probability. It is shown that a 4-region RFA scheme provides almost double performance gain over a 2-region RFA scheme for the same set of parameters.