Power-Aware Coexistence of Wi-Fi and LTE in the Unlicensed Band Using Time-Domain Virtualization

Abstract

The rapid increase of mobile devices requires more network capacity as limited licensed spectrum is diminishing access to long-term evolution (LTE) users. As increasing licensed spectrum becomes costly, a cost-effective solution that improves network capacity is needed. Another overlooked issue is spectrum efficiency, where unused resources could be allocated to more LTE users. This article proposes two solutions to address network capacity and spectrum efficiency: moving into unlicensed spectrum and implementing wireless resource virtualization. In addition, as these solutions enhance data rate, thus increasing power consumption, this article includes power-aware optimization as a solution. Operating in the unlicensed band poses a challenge as 5-GHz bands are predominately used by Wi-Fi systems. Based on this challenge, we are proposing a time-sharing wireless resource virtualization (WRV)-based LTE/Wi-Fi coexistence solution that considers joint resource/access point (AP) allocation and power control problems for both technologies. Accordingly, we formulate a mixed-integer nonlinear programming problem and solve using the Lagrangian dual decomposition. We also propose low-complexity heuristics to solve these problems. Results show that the coexistence of Wi-Fi and LTE can be achieved in the unlicensed band with improved power savings using virtualization. Moreover, there is little to no difference in power savings in heterogeneous-traffic scenarios as the algorithm prioritizes maximizing rate to minimizing power.