Coexistence Performance and Limits of Frame-Based Listen-Before-Talk

Frame-based listen-before-talk (FB-LBT) has been adopted as one of the channel access mechanism for Wi-Fi/LTE coexistence. We aim to explore the limits of FB-LBT by developing theoretical models to characterize the FB-LBT channel access performance under the coexistence of LTE and Wi-Fi. We first derive a steady-state model to calculate the spectrum share occupied by LTE under the assumption that the Wi-Fi transmissions have stationary distributions. The assumption does not hold when the time between two LTE transmissions is short, where the system is dominated by a dynamic phenomenon. A second model is developed that accounts for the dynamics of the Wi-Fi channel access mechanism. Our models, validated by simulation results, accurately calculate the spectrum share occupied by LTE over a range of FB-LBT frame periods and Wi-Fi traffic loads. We obtain upper bounds on the FB-LBT spectrum share when competing with heavy Wi-Fi traffic, which confirm the weakness of FB-LBT. Moreover, we demonstrate that our models can be used to control the FB-LBT spectrum share within a modest range.