On the SINR Distribution of Grant-Free Random Access With Moderate MIMO
Jinho Choi · IEEE Wireless Communications Letters · 2020
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.