Throughput–Power Tradeoff Association for User Equipment in WLAN/Cellular Integrated Networks

To meet the dramatic growth in mobile traffic, wireless local area networks (WLANs) have been integrated with cellular networks. We investigate the user equipment (UE) association problem in WLAN/cellular integrated networks from game-theoretic perspective by taking into account throughput and power consumption. In the case of WLAN offloading, random uplink traffic from UEs inevitably brings contention and collisions into WLANs; thus, the capacity of a WLAN system is decreased. To eliminate this side effect, UEs are encouraged to deliver uplink traffic over contention-free cellular networks. However, UEs will consume much more power when their uplink traffic is delivered over cellular networks instead of WLANs. Observing the above contradiction between throughput and power consumption, we define a utility function to reconcile the contradiction and formulate the UE association problem as a game. An incentive mechanism is involved to encourage UEs with enough energy to redirect their uplink traffic over cellular networks. We prove that this game is an exact potential game with at least one pure-strategy Nash equilibrium. Then, a distributed algorithm is proposed for each UE to determine its uplink association. Finally, extensive numerical simulations validate the feasibility and effectiveness of the proposed association strategy.