A dynamic subcarrier exchange scheme for SFR-aided LTE networks

In the orthogonal frequency division multiplexing (OFDM) aided long term evolution (LTE) system, the intra-cell interference can be effectively suppressed by excellent orthogonality between the subcarriers within the same serving cell. However, the inter-cell interferences (ICI) still exist, since the neighbor cells employ the same frequency bands as the serving cell does, deteriorating the system performance especially at the cell edge. Soft frequency reuse (SFR) schemes have therefore been proposed to mitigate the ICI issue for capacity improvements at cell edge. Nonetheless, the allocation of subcarriers in SFR reduces spectral efficiency in specific cell areas, for both cell center and cell edge scenarios, resulting in the decrease of the system throughput. In this paper, we propose to improve the system throughput by dynamically allocating and exchanging the subcarriers among different cells. In the proposed dynamic subcarrier exchange (DSE) scheme, the same major subcarriers are not allowed to be used by the adjacent cell edge for ICI suppression purpose. In each scheduling period, each cell dynamically determines its own major subcarriers based on the available spectrum usage information. Thus, the spectrum bands are allocated distributedly and the multiple cells share the spectrum bands in a cooperative way. Simulation results demonstrate that the proposed DSE scheme significantly improves the spectrum utilization and achieves higher system throughput than its SFR counterpart.