Hybrid Cellular/WLAN Networks with Wireless Offloading: A Novel Communication Paradigm

The exploitation of already deployed wireless local area networks (WLAN)s (e.g., WiFi access points (AP)s) has attracted considerable attention, as an efficient and practical method to improve the performance of wireless networks. In this paper, we propose a novel communication paradigm to satisfy the performance demands of the future wireless networks: a hybrid Cellular-WLAN network architecture with wireless offloading. In contrast to the commonly adopted practice of the WiFi offloading, where the WLAN APs have a wired backhaul (e.g., Digital Subscriber Line), we propose a wireless offloading approach, where the WLAN APs will share their wireless cellular broadband connection with other users. These users will select their serving node, i.e., the macro-cell base station or a WLAN AP, based on a certain selection criterion, originating a challenging research field, where interfering effects and wireless resources limitations play a dominant role. Important performance metrics of the proposed hybrid scheme -as the outage probability and the average signal-to-interference-plus noise ratio (SINR)are theoretically studied and closed form expressions are derived for the singleuser case with multiple interferers, considering both identical and non-identical fading channels. Furthermore, considering a multicell network scenario the proposed hybrid scheme is optimized for minimizing the intercell interference. Moreover, based on the general multi-cellular hybrid WLAN/Celullar concept, we present a novel scheme for achieving frequency reuse one within a single macro-cell, under specific performance criteria and constraints, that guarantee the overall cell’s or the individual user’s quality-of-service requirements. We consider two optimization problems that aim at the overall cell’s SINR maximization or at the minimum user’s SINR maximization and we propose a fast greedy solution for both of them. Numerical results and simulations showed that the proposed wireless architecture may offer significant performance gains in the presence of multiple interferers, compared to a conventional cellular network.