Link adaptation for downlink 5G ultra-reliable low latency communication (URLLC) is quite challenging. While reduced feedback schemes for link adaptation are crucial to achieve high spectral efficiency, accuracy of sub-band channel quality indicator (CQI) reports is more critical in 5G URLLC because of the ultra-high reliability and efficient resource utilization requirements. The existing differential feedback mechanism cannot reconstruct sub-band CQIs at the BS exactly. In this paper, existing differential feedback mechanism for link adaptation is first investigated using analytical and simulation models to verify its limitations in reconstructing the sub-band CQIs and to study its impact on URLLC reliability and resource utilization efficiency. Then a cognitive link adaptation using a controlled differential feedback scheme for sub-band CQIs is proposed based on the investigations. Extensive simulation results are provided to show the superior performance of the proposed cognitive solution and to illustrate the theoretical analysis.

中文翻译：

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5G URLLC 的认知子带调度和链路自适应


下行5G超可靠低时延通信（URLLC）的链路适配相当具有挑战性。虽然减少链路自适应反馈方案对于实现高频谱效率至关重要，但由于超高可靠性和高效资源利用的要求，子带信道质量指示符 (CQI) 报告的准确性在 5G URLLC 中更为关键。现有的差分反馈机制无法准确地重建BS处的子带CQI。本文首先利用分析和仿真模型研究了现有的链路自适应差分反馈机制，以验证其在重建子带CQI方面的局限性，并研究其对URLLC可靠性和资源利用效率的影响。然后基于研究提出了一种针对子带 CQI 使用受控差分反馈方案的认知链路自适应方法。提供了大量的模拟结果来显示所提出的认知解决方案的优越性能并说明理论分析。