為了滿足日漸增長流量需求，行動網路營運商將免執照頻段引入到LTE中，使其得到更大的頻寬。但若沒有公平的共存方法，將會嚴重危害目前在免執照頻段中Wi-Fi的效能。在本篇論文，我們提出一套利用Wi-Fi競爭視窗大小來分配占空比的共存方法。我們在LTE基地台中安裝虛擬Wi-Fi傳送節點，利用該節點來模擬分散式協調功能，得到目前網路中競爭視窗大小，根據平均競爭視窗大小估算目前Wi-Fi網路的流量，分配合適的占空比。我們提出的共存方法可以保證Wi-Fi與LTE之間的公平性，並提高頻譜使用效率。最後，我們利用NS3這套模擬軟體去評估我們與其他共存方法的效能。;In order to satisfy increasing traffic demands, LTE-U offloads its traffic on unlicensed channels by aggregating its licensed and unlicensed carriers. However, coexistence of LTE-U and unlicensed users such as WiFi causes significant interference, which degrades the throughput of WiFi systems. In this paper, we propose fair coexistence scheme that allocates LTE-off period (i.e., time for WiFi transmissions) according to Wi-Fi traffic volume. We can estimate Wi-Fi traffic level based on average contention window size. Simulation results show that our coexistence scheme outperforms state-of-the-art techniques in terms of fairness.
