Load balancing with transmission power control in femtocell networks

Femtocells applied in many existing systems, such as HSPA, 3GPP LTE, WiMAX, and etc, which cover a short range and offer an economically viable way to improve cellular system capacity, have caught world-wide researching interest nowadays. The primary purpose of femtocell solutions has been to improve indoor coverage in current cellular systems. Here, users that are moved to femtocells experience increased throughput due to shorter ranges, while using the cable backhaul to reach the network gateway. However, more importantly, the smaller size of femtocells increases the system capacity by enabling spatial reuse, whereby multiple femtocell transmissions can be executed on the same channel in a macro cell. But existing femtocell solutions only increase the network capacity without considerations of fairness of per femtocell user equipment (FUE) capacity. In this paper, we propose a load balancing scheme with the optimal fairness of per FUE capacity on 3GPP systems, which is split into two steps named interference recognition and femtocell load balancing, respectively. In interference recognition step, the interference graph is created on the basis of the interference detection mechanisms consisting of user equipment measurement (UMR) and femtocell cooperation message (FCM). In femtocell load balancing step, we reallocate femtocell user equipments (FUE) to FAPs based on the interference relationship. By extensive simulations, it has been proved that the proposed scheme can effectively allocate FUEs to FAPs to increase the minimum capacity of FUE. This means that the proposed scheme leads the optimal FUE allocation in terms of fairness of per UE capacity.