Coordinated Tethering for Multi-RAT Cellular Networks: An Algorithmic Solution and Performance Analysis

Abstract

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 beyond 4G wireless networks. In this paper, we propose a novel communication paradigm to satisfy the performance demands of future wireless networks: a hybrid Cellular/WLAN network architecture with wireless offloading. In contrast to the commonly adopted practice of 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 eNodeB or a WLAN AP, based on a certain selection criterion. Thus a challenging research field is originated, where interfering effects and wireless resources limitations play a dominant role. Important performance metrics of the proposed hybrid scheme, including the bit error probability, the ergodic capacity and the average signal-to-interference-plus noise ratio, are theoretically studied and closed form expressions are derived for the single-user case with multiple interferers, for both identical and non-identical fading conditions. Also, based on the general multi-cellular hybrid WLAN-Cellular concept, we first propose a intercell interference minimization approach. Then we present a novel scheme for achieving frequency reuse equal to one within a single macro-cell, under specific performance criteria and constraints, that guarantee the overall cell or the individual user QoS requirements.