On the Fundamental Limits of MIMO Massive Multiple Access Channels
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In this paper, we study multiple-antenna wireless communication networks where a large number of devices simultaneously communicating with an access point. The capacity region of multiple-input multiple-output massive multiple access channels (MIMO mMAC) is investigated. While the joint typicality decoding is utilized to establish the achievability of capacity region for conventional multiple access channel with fixed number of users, the technique is not directly applicable for MIMO mMAC [4]. Instead, an information-theoretic approach based on Gallager's error exponent analysis is exploited to characterize the capacity region of MIMO mMAC. Theoretical results reveal that the capacity region of MIMO mMAC is dominated by the sum rate constraint only and the individual user rate is determined by a specific factor that corresponds to the allocation of sum rate. The individual user rate in conventional MAC is not achievable with massive multiple access and the successive interference cancellation cannot guarantee an arbitrary small decoding error probability for MIMO mMAC. The capacity region of MIMO mMAC is a generalization of the symmetric rate in [5].
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