Joint User Association and Data-Rate Allocation in Heterogeneous Wireless Networks

Abstract

In this paper, the problem of joint data-rate allocation and mobile terminal (MT) assignment is investigated in a heterogeneous wireless network (HetNet) environment that consists of wireless local area network (WLAN) access points (APs) and cellular base stations (BSs) for a best-effort service. MTs are equipped with multiple radio interfaces and have multihoming capabilities. As a result, MTs can connect simultaneously to more than one wireless network (e.g., cellular network BS and WLAN AP) and aggregate the offered bandwidths from these networks to support applications with high required data rates. Unlike the existing research, to account for the MT's limited number of radio interfaces and the abundant wireless network options, the joint MT assignment and data-rate allocation problem is formulated to select the optimal subset of networks for each MT and allocate the optimal data rate share from this subset to maximize the HetNet total utility. The problem is formulated as a mixed-integer nonlinear program (MINLP), and due to its intractability and computational complexity, we transform the problem into a convex optimization problem via a binary variable relaxation approach. Based on the mathematical analysis of the problem, we present a heuristic algorithm for joint MT assignment and data-rate allocation. Numerical results demonstrate that the proposed solution achieves a near-optimal MT assignment and data-rate allocation at reduced computational complexity.