Coexistence analysis of LTE and WLAN systems with heterogenous backoff slot durations

To enable constructive coexistence with wireless local area networks (WLANs), unlicensed long-term evolution (LTE) systems use listen before talk (LBT) as a major candidate technique. The LBT has a flexible backoff idle slot duration, which can be significantly larger than the WLAN counterpart. To our knowledge, however, available analytical results on the LTE and WLAN coexistence have considered only identical idle backoff slot durations. There is a formidable technical difficulty to coexistence analysis for different backoff slot durations. In this paper, we develop a new technical approach to address this open issue. First, we point out an LBT backoff slot jamming effect, and propose a modified LBT backoff scheme to address this problem. Second, for our proposed LBT scheme, we develop a new analytical framework to address system interactions with non-equal backoff slot durations, model the LTE backoff process as super-counters, and provide a thorough analysis on the throughput, backoff counter hold time, and successful transmission probabilities of LTE-LBT and WLAN systems. Finally, we program the algorithms and use computer simulation to validate the analysis. This result fills a major gap and provides practical value for LTE-LBT and WLAN coexistence performance analysis with heterogeneous sensing and backoff slot durations.