Contention window adaptation of listen-before-talk scheme for LTE and Wi-Fi coexistence in unlicensed spectrum

Harmonious coexistence between LTE with Licensed-Assisted Access (LTE-LAA) and WIFI is a research issue due to deploying LTE to unlicensed spectrum 5GHz. Listen-before-talk (LBT) scheme works as a requisite in unlicensed spectrum to ensure the fairness among different radio access technologies (RATs). To reduce the collision caused by relatively fixed contention window (CW) of LBT scheme and ensure the fairness between LTE and WIFI, in this paper, we propose an enhanced LBT scheme which adjusts CW based on LTE small cell medium sensing the state of channel. Besides, the enhanced LBT scheme is modeled as one-dimensional Markov chain to analyze the behavior of LTE small cell and calculate the expected throughput. Simulation results indicate that the proposed LBT scheme can let WIFI and LTE gain nearly equal throughput and reduce the collision probability in LTE-WIFI coexistence scenario, besides, the total throughput also promotes.