QoS Constrained Optimization of Cell Association and Resource Allocation for Load Balancing in Downlink Heterogeneous Cellular Networks

• Gongchao Su,
• Bin Chen,
• Xiaohui Lin,
• Hui Wang,
• Lemin Li,

Vol. 9, No. 5, May 30, 2015
10.3837/tiis.2015.05.001, Download Paper (Free):

• load balancing
• heterogeneous cellular networks
• Optimization
• regularization

Abstract

This paper considers the optimal cell association and resource allocation for load balancing in a heterogeneous cellular network subject to users quality-of-service (QoS) constraints. We adopt the proportional fairness (PF) utility maximization formulation which also accommodates the QoS constraints in terms of minimum rate requirements. With equal resource allocation this joint optimization problem is either infeasible or requires relaxation that yields a solution which is difficult to implement. Nevertheless, we show that this joint optimization problem can be effectively solved without any priori assumption on resource allocation and yields a cell association scheme which enforces single BS association for each user. We re-formulated the joint optimization problem as a network-wide resource allocation problem with cardinality constraints. A reweighted heuristic l1-norm regularization method is used to obtain a sparse solution to the re-formulated problem. The cell association scheme is then derived from the sparsity pattern of the solution, which guarantees a single BS association for each user. Compared with the previously proposed method based on equal resource allocation, the proposed framework results in a feasible cell association scheme and yields a robust solution on resource allocation that satisfies the QoS constraints. Our simulations illustrate the impact of user’s minimum rate requirements on cell association and demonstrate that the proposed approach achieves load balancing and enforces single BS association for users.

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