Dynamic spectrum allocation for cell range extension in tiered Macro-Pico heterogeneous networks

Heterogeneous networks are employed in the next generation communication systems to enhance the area spectral efficiency (ASE), where cell range extension (CRE) is a promising technique to improve the cell edge performance and utilize the low power node (LPN) resources more effectively. In this paper we propose a dynamic spectrum allocation scheme for Macro-Pico scenario to mitigate both the co-tier and cross-tier interferences. The available system spectrum is divided into different parts by four steps, i.e. user set partition, service request collection, cross-tier occupation and CRE occupation decision, while the service request of each user is taken into consideration. During the process implementation, the reference signal receiving power (RSRP) threshold is derived by mathematical means to judge cell edge macro users when a predefined ratio is given. Simulation results show that the proposed scheme reaches almost the same cell edge performance with the best existing option, meanwhile provides higher overall system throughput and better spectral efficiency. Therefore, much better balance is achieved.