This letter aims to analyze and optimize the status update performance in a grant-free random access system with massive multiple-input multiple-output. We analyze the status update process, and derive a closed-form approximate expression of the average age of information (AoI). Then, in the asymptotic case where the large number of antennas at the base station causes the packet error rate to approach zero, we jointly optimize access control and pilot length to reduce the average AoI. Simulation and numerical results verify the correctness of the theoretical analysis, and show that the proposed scheme can achieve the same performance as the exhaustive search scheme and outperforms the benchmark ones.

中文翻译：

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具有大规模 MIMO 的免授权随机接入中的信息时代

这封信旨在分析和优化具有海量多输入多输出的无授权随机访问系统中的状态更新性能。我们分析状态更新过程，并推导出平均信息年龄（AoI）的封闭形式近似表达式。然后，在基站大量天线导致误包率接近零的渐近情况下，我们联合优化接入控制和导频长度以降低平均AoI。仿真和数值结果验证了理论分析的正确性，表明所提出的方案可以达到与穷举搜索方案相同的性能，并优于基准方案。