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.

本文提出了一种延迟均衡的自适应信道分配（DB-ACA）机制，以提高LTE-U和WiFi共存系统的信道访问性能。为了支持DB-ACA机制，引入了一个集成的网络体系结构来协调共存系统中的通道访问。基于集成网络体系结构，共存系统能够根据共存系统的当前业务负载状况，分别自适应地调整分配给LTE-U系统和WiFi系统的未许可信道的数量。为了确保LTE-U和WiFi系统的访问公平性，DB-ACA机制引入了公平性标准，要求在LTE-U和WiFi系统之间的非许可频段上平衡信道访问延迟。开发了理论模型来确定需要调整的未许可信道的数量，并推导了性能模型来分别分析LTE-U系统和WiFi系统的阻塞概率和访问延迟。通过仿真结果验证了性能模型的有效性。数值结果表明，所提出的DB-ACA机制可以有效地保证共存系统的访问公平性，并在阻塞概率和访问延迟方面显着提高系统性能。