An efficient location aware distributed physical resource block assignment for dense closed access femtocell networks

Abstract

The demand for higher data-rate in the indoor environment is unrelenting, and has triggered a huge deployment of Femto Base Stations (FBSs) in such environments. A large portion of these FBSs are privately owned and operate in closed access mode. However, due to aggressive spectrum reuse among these FBSs, co-tier interference is very high. Techniques relying on Fractional Frequency Reuse (FFR) will not scale in these dense FBS networks as the effective available spectrum per FBSs will be a little to support any meaningful data-rate at any FBS. Moreover, the techniques that use both power control and sub-channel allocation usually operate in a centralized fashion. Hence, these are a huge burden to the entire system. To handle this additional interference without significantly affecting spectrum efficiency, efficient location aware Physical Resource Block (PRB) assignment among interfering FBSs is necessary. In this paper, we formulate the PRB assignment problem as a Mixed Integer Non-Linear Program (MINLP) that exploits User Equipment (UE) location with respect to its interfering FBSs. Since the optimization problem is NP-hard, we propose a twofold solution which can efficiently reuse the PRBs while maintaining the interference below a threshold. First, an iterative elimination algorithm for PRB allocation and second, an adaptive PRB power control to find the required transmission power which minimizes interference. The proposed technique operates in a distributed manner and improves per FBS PRB reuse, energy efficiency, system blocking. Obtained results are verified using extensive simulations.