Energy-Efficient WiFi Offloading and Network Management in Heterogeneous Wireless Networks

We consider the joint WiFi offloading, admission control, and network management for the integrated WiFi and OFDMA-based cellular network. Specifically, we propose a quality-of-service (QoS) and mobility-aware admission control scheme that efficiently offloads macrocell traffic to WiFi and integrates a novel bandwidth borrow-return strategy while guaranteeing QoS requirements for users. These QoS constraints are explicitly modeled considering the throughput performance of carrier sense multiple access with collision avoidance scheme in the IEEE 802.11 WLAN and the fractional frequency reuse in the downlink cellular network. Then, we develop an analytical model to derive the blocking probabilities for calls in different service areas of a cell. Based on this analysis, we study the joint base station switching, power control, and traffic offloading problem for energy minimization under QoS constraints. We consider the time-varying call traffic and develop an algorithm to find the optimal solution of the problem. Numerical results are presented to demonstrate the performance of the proposed cross-layer resource management framework in the integrated network.