Future unlicensed spectrum sharing scenarios involve multi-cell, multi-tier access of incumbent and emerging wireless systems, such as wireless local area network (WLAN), new-radio unlicensed (NR-U), and long-term evolution (LTE)with licensed assisted access (LAA). Listen-before-talk (LBT) medium access control (MAC) is a common technique used for channel sensing and access control. Despite intense research effort, the majority of available results have not accurately analyzed imperfect spectrum sensing and multi-cell LBT. Furthermore, while past works involved two major spectrum sharing strategies - shared cell access (SCA) and exclusive cell access (ECA), there lacked a systematic comparison between the two. In this paper, we develop a unified analytical approach which maps the effects of imperfect spectrum sensing and multi- cell, multi-tier LBT to the achieved key performance indicators (KPIs) of LAA and WLAN cells. We provide an analytical comparison between the SCA and ECA schemes, and show that the SCA can provide a significantly higher system throughput than the ECA as a function of sensing thresholds. By developing a new simulation method, we program the SCA and ECA algorithms and implement Monte Carlo simulations, which verify our analytical results. Numerical results provide insightful observations on effects of various parameters. This result provides powerful analytical and simulation tools to evaluate the performance of multi-tier LBT coexistence systems with imperfect sensing, and effectively supports coexistence system optimization.
The 2020 IEEE 91st Vehicular Technology Conference: VTC2020-Spring
May 25-28, 2020
Imperfect spectrum sensing, LTE-LAA, Multi-cell LBT, Multi-tier coexistence, WLAN