Fair and Efficient Channel Observation-Based Listen-Before Talk (CoLBT) for LAA-WiFi Coexistence in Unlicensed LTE

Abstract

License Assisted Access-WiFi (LAA-WiFi) coexistence allows the operations on the unlicensed spectrum for Long Term Evolution (LTE) along with existing unlicensed wireless local area networks (WLANs). The current spectrum access process of legacy WLANs uses clear channel assessment (CCA) and carrier sense multiple access with collision avoidance (CSMA/CA), where the spectrum is sensed before use and a random binary exponential backoff (BEB) mechanism is employed for collision avoidance. While LAA uses a listen-before-talk (LBT) mechanism, moderately similar to the CCA CSMA/CA for channel access. However, there is a fairness issue when these two technologies coexist. In this paper, we propose a channel observation-based LBT (CoLBT) mechanism for fairness in LAA-Wi-Fi coexistence scenarios. Specifically, we introduce a more realistic practical channel observation-based collision probability observed by the LAA evolved Node B (eNB) to adaptively scale-up and scale-down the backoff contention window for channel contention, to reduce the waste of resources and improve LAA-WiFi coexistence performance. Simulation results validate that the proposed CoLBT mechanism is effective in LAA-WiFi coexistence scenario and can improve fairness performance, compared with the current mechanism of LBT.