Load Balancing in Two-Tier Cellular Networks With Open and Hybrid Access Femtocells

Femtocell base station (BS) is a low-power, low-price BS based on the cellular communication technology. It is expected to become a cost-effective solution for improving the communication performance of indoor users, whose traffic demands are large in general. We propose long-term parameter optimization schemes for open and hybrid femtocells, which maximize the average throughput of macrocell users by offloading the macro users' downlink traffic to femtocells. To achieve this goal, load balancing between femtocells and macrocells is needed, and hence, we jointly optimize the ratio of dedicated resources for femtocells as well as the femtocell service area in open access femtocell networks by numerical analysis. Then, we extend our algorithm to hybrid access femtocells, where some intra-femtocell resources are dedicated only for femtocell owners, while remaining resources are shared with foreign macrocell users. Our evaluation results show that the proposed parameter optimization schemes significantly enhance the performance of macrocell users because of the large offloading gain. The benefits provided to femtocell users are also adaptively maintained according to the femtocell users' requirements. The results in this paper also provide insights about the situations where femtocell deployment on dedicated channels is preferred to the cochannel deployment.