Frequency-swapping aided femtocells in twin-layer cellular networks relying on fractional frequency reuse

Femtocells constitute an economical solution conceived for improving the indoor coverage, which are capable of achieving a high network capacity. In order to guarantee a high Area Spectral Efficiency (ASE), femtocells have to reuse the spectrum of macrocells. As a result, the performance of both the femtocells and macrocells may suffer owing to the near-far effects. In this paper, we investigate the Outage Probability (OP) of twin-layer cellular networks, where the Macrocell Base Stations (MBSs) employing Fractional Frequency Reuse (FFR) host the Femtocell Base Stations (FBSs). More explicitly, the frequency-swapping aided femtocell concept is proposed for overcoming the typical near-far problem. We derive the approximate closed-form expressions for the DownLink (DL) OP for both our benchmarker as well as for our proposed solution. Our analysis demonstrates that the OP of femtocell users in the Cell Centre Region (CCR) and that of the macrocell users in the Cell Edge Region (CER) will be reduced by the proposed swapped-spectrum access policy.