Uplink Performance Improvement by Frequency Allocation and Power Control in Heterogeneous Networks

The cell association based on the maximum downlink received power is optimal in a conventional homogeneous network, but this association is not particularly suitable for heterogeneous networks (HetNets). Therefore, the concept of downlink and uplink decoupling (DUDE) is proposed for improving uplink performances of HetNets. However, in DUDE association scheme, macro user equipment (MUE) will suffer more interference from the offloaded users in uplink. In this paper, we investigate uplink interference mitigation through frequency reuse and power control schemes. The reverse frequency allocation (RFA) scheme is adopted to alleviate the cross-tier interference by increasing the distance between users of the same frequency. Then, a dynamic distributed power control (DDPC) with user admission control is proposed to further improve the uplink users performance and system spectrum utilization. The DDPC mitigates co-channel interference by dynamically updating transmitting power of active users and new access users, meanwhile it can maintain the link quality of active users above given signal to interference plus noise ratio (SINR) thresholds at all times. The dynamics and performance of the network are investigated through simulation experiments in terms of average SINR, evolution of uplink transmitting power, uplink SINR, and dynamic adjusting factor. The simulation results show that, in comparison with the DUDE scheme and DUDE with RFA scheme, DUDE with RFA and DDPC scheme can achieve a better quality of service (QoS) and uplink data rate performance.