Network operators are looking toward LTE License Assisted Access (LAA) as a means of extending capacity by offloading traffic to unlicensed bands. However, operation in these bands requires abiding by certain coexistence rules in terms of channel access. The description of these rules in the existing literature is not always in line with the latest standards. Therefore, in this article, we clarify the operation of LAA, focusing on channel access and methods of providing quality of service (QoS) support. In terms of coexistence, we evaluate the impact of LAA under its various QoS settings on WiFi performance in an experimental testbed. Finally, we describe the upcoming research challenges for LTE-based technologies in unlicensed bands considering the latest developments.

中文翻译：

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重访LTE LAA：通道访问，QoS和WiFi共存

网络运营商正在寻求LTE许可辅助访问（LAA），以通过将流量卸载到非许可频段来扩展容量。然而，在这些频带中的操作需要在信道访问方面遵守某些共存规则。现有文献中对这些规则的描述并不总是与最新标准一致。因此，在本文中，我们将重点介绍通道访问和提供服务质量（QoS）支持的方法，从而阐明LAA的操作。在共存方面，我们在实验性测试平台上评估了LAA在其各种QoS设置下对WiFi性能的影响。最后，我们结合最新发展情况，描述了在免许可频段中基于LTE的技术所面临的研究挑战。