With a limited bandwidth to support massive connectivity in machine-type communication (MTC), various massive multiple-input multiple-output (MIMO) based random access schemes have been studied. Among those, in particular, grant-free random access with massive MIMO for short message delivery from devices and sensors is promising thanks to low signaling overhead. While asymptotic analysis becomes straightforward with the number of antennas approaching infinity, in practice, the number of antennas is limited, making asymptotic analysis useless. For non-asymptotic analysis, in this letter, we derive an approximate closed-form expression for the distribution of the signal-to-interference-plus-noise ratio (SINR) in grant-free random access with moderate (not massive) MIMO.

中文翻译：

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具有中等MIMO的无授权随机接入的SINR分布

由于在机器类型通信 (MTC) 中支持大规模连接的带宽有限，已经研究了各种基于大规模多输入多输出 (MIMO) 的随机接入方案。其中，尤其是具有大规模 MIMO 的免授权随机访问用于从设备和传感器传输短消息，由于信令开销低，因此很有前景。虽然随着天线数量接近无穷大，渐近分析变得简单，但在实践中，天线数量是有限的，使得渐近分析变得无用。对于非渐近分析，在这封信中，我们推导出了具有中等（非大规模）MIMO 的免授权随机接入中信干噪比 (SINR) 分布的近似封闭形式表达式。