Performance evaluation of frequency planning schemes in OFDMA-based networks

In this paper, we study the performance of frequency allocation schemes in forthcoming OFDMA-based systems. These systems include WiMAX and 3G long term evolution. We first develop an analytical model for the collisions for an arbitrary number of users in the different cells. We then calculate the capacity of the system using a Markov model and taking into account the inter-cell interference and its impact on the adaptive modulation. We apply this model to compare four frequency allocation schemes, namely reuse 1, reuse 3, and static and dynamic mixes of reuse 1 and 3. We also considered a fifth scheme, called partial isolation and proposed for 3G LTE systems, that uses different transmission powers in the different frequency bands, in order to reduce interference at cell edge. Our results show that the partial isolation scheme outperforms all the others, especially in the downlink, as it combines the advantage of the reuse 1 scheme (large overall throughput) with that of the mix of reuses 1 and 3 (good cell-edge performance).