Performance Improvement of Heterogeneous Networks with Backhaul Constraint through Decoupled Uplink and Downlink Access Policy

One of the major challenges in the heterogeneous networks, where different base stations with different capabilities serve users, is the access policy for establishing a communication link between the user and its serving node. To overcome this challenge in a heterogeneous network which also suffers from the backhaul constraint, a special kind of “decoupled uplink and downlink access” policy is proposed in this paper, which let users to be served by different base stations in uplink and downlink communications. More precisely, in order to efficiently utilize the system resources, increase the users’ throughput, and guarantee the users’ fairness, a special load balancing association policy is considered in the uplink transmission and a problem which maximizes the weighted sum of users’ effective rates is solved. Simulation results show that using this association policy for the considered scenario, significantly improves the load balancing index, energy efficiency, and also users’ effective rate compared to the scenario which considers the criterion of the maximum received power of the downlink connection for both uplink and downlink transmissions. In addition we propose an algorithm which further improves the load balancing considering the backhaul constraint of the base stations and evaluate its efficiency.