Joint resource block assignment and power control in macro-pico heterogeneous networks

In macro-pico heterogeneous networks, Cell Range Expansion (CRE) is introduced to perform load balance between macrocell and picocell. However, the cross-tier interference from Macro Base Station (MBS) severely degrades the performance of pico CRE User Equipments (UEs) and total system throughput. Therefore, a joint Resource Block (RB) assignment and power control algorithm is proposed to alleviate this influence. In pico layer, all RBs are assigned to the pico UEs (PUEs) in Round-Robin (RR) manner, and CRE UEs of several picocells in certain range reuse the same RBs as much as possible. In macro layer, these overlapping RBs are assigned to the Macro UEs (MUEs) who have a better experience in turn. Then a utility function combining interference and throughput is calculated to find the optimal transmission power of each MBS in overlapping RBs for throughput enhancement by using Differential Evolution (DE) theory. Simulation results show that our algorithm could significantly improve the performance of pico CRE UEs as well as total system throughput.