近年來因為長期演進技術(Long Term Evolution, LTE)網路中流量使用量遽增，導致授權頻譜(Licensed spectrum)吃緊，第三代合作夥伴計畫(The Third Generation Partnership Project, 3GPP)提出使用免執照頻段(Unlicensed spectrum)來減輕這方面的負擔，但這會造成LTE訊號影響WiFi傳輸效能。為了達到兩者公平使用免授權頻譜的目的，3GPP提出免執照LTE(LTE-Unlicensed band, LTE-U)與授權輔助接取(License Assisted Access, LAA)兩種LTE免授權頻段接取技術。
在本論文中，根據探討ETSI、3GPP與IEEE之標準現況，除了簡單分類WiFi與LTE於免執照頻段的技術之外，提出模擬WiFi與LTE(LTE-U、LAA)於免執照頻段共存時的方法，相關的模擬結果除了可以了解到WiFi與LTE(LTE-U、LAA)於免執照頻段共存時各自的系統表現外，亦可提供給設計LTE使用未授權頻譜技術者參考進而改進處於此情境時的WiFi系統表現。

In recent years, Long Term Evolution (LTE) network traffic is dramatic growing so that licensed spectrum will be no longer enough to be used. The third Generation Partnership Project(3GPP) proposes that enabling LTE to operate in unlicensed spectrum in order to offload data traffic from licensed band, however, it will cause LTE signal influences effectiveness of WiFi transmission. So as to achieve the purpose of the fair sharing of unlicensed spectrum, 3GPP provides two kinds of LTE accessing unlicensed band technologies, LTE in Unlicensed band(LTE-U) and License Assisted Access (LAA).
In this paper, according to the result of studying of the status of ETSI, 3GPP and IEEE standards, there is not only simple categorizing the technologies which WiFi and LTE used in unlicensed spectrum but also proposing the method of simulation for studying the coexistence between WiFi and LTE (LTE-U, LAA) in unlicensed spectrum. The simulation result not only shows the performances of WiFi and LTE(LTE-U、LAA) but also provides the reference to the designer of LTE accessing unlicensed spectrum technologies to improve the WiFi system performance in this architecture.

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