Learning-Assisted Clustered Access of 5G/B5G Networks to Unlicensed Spectrum

License-assisted access (LAA) to unlicensed spectrum is a potential solution to improve the resource availability and system scalability of 5G/ B5G networks. Challenges arise from coexistence between LAA and incumbent systems, especially the ubiquitous IEEE 802.11 WiFi systems. This article demonstrates that the coexistence can be substantially improved by leveraging learning-based clustering of small base stations (SBSs), referred to as learning-assisted clustered access (LACA), and improving the interoperability between licensed and unlicensed access. Fast signaling and a centralized control plane of licensed access can facilitate clustering SBSs for coordinated access to the unlicensed spectrum, hence reducing the number of parties contending for access and alleviating contention. Appropriate clustering of SBSs is important to the efficiency of LACA in 5G/B5G networks. LACA can quickly converge with strong locality, facilitating the coordination of the SBSs, for example, cooperatively connecting multiple users and conducting beamforming. Analytic evaluation and numerical tests confirm the improved coexistence through enlarged LAA-WiFi capacity regions, as well as reduced transmission delays.

Introduction

Current wireless networks are undergoing unprecedented explosive growth in mobile data traffic. It is predicted that mobile data traffic will reach 30.6 EB per month by 2020 [1]. Given the scarcity of radio spectrum that is suitable for wireless communication, conventional approaches of increasing the spectral efficiency in the licensed bands (including multi-antenna techniques and ultra-dense deployment of small base stations [SBSs] [2]–[4]) are becoming less effective in coping with this dramatic growth of mobile data. A new and increasingly accepted approach to meeting the explosive growth of mobile data traffic is to exploit the unlicensed bands, such as the 2.4 GHz and 5.8 GHz industrial, scientific, and medical (ISM) bands, to increase the capacity of cellular systems [5]. License-assisted access (LAA) has recently been proposed by the Third Generation Partnership Project (3GPP) to extend long-term evolution (LTE) systems to the unlicensed bands [6]. LAA is anticipated to be a significant solution to improve the resource availability and system scalability in future 5G/B5G networks [7].