A Delay Balanced Adaptive Channel Allocation Mechanism for LTE-U and WiFi Coexistence Systems

This paper proposes a delay-balanced adaptive channel allocation (DB-ACA) mechanism for improving the channel access performance of an LTE-U and WiFi coexistence system. To support the DB-ACA mechanism, an integrated network architecture is introduced for coordinating the channel access in the coexistence system. Based on the integrated network architecture, the coexistence system is able to adaptively adjust the number of unlicensed channels allocated to the LTE-U system and WiFi system, respectively, according to the current traffic load status of the coexistence system. To ensure the access fairness of the LTE-U and WiFi systems, the DB-ACA mechanism introduces a fairness criterion, which requires that the channel access delay be balanced on the unlicensed band between the LTE-U and WiFi systems. Theoretical models are developed to determine the number of unlicensed channels that need to be adjusted, and performance models are derived to analyze the blocking probability and access delay of the LTE-U system and WiFi system, respectively. The effectiveness of the performance models is validated through simulation results. It is demonstrated through numerical results that the proposed DB-ACA mechanism can effectively ensure access fairness of the coexistence system, and significantly improve the system performance in terms of the blocking probability and access delay.