Abstract
A novel random access scheme for M2M communication in crowded asynchronous massive MIMO systems
Highlights
The machine-to-machine (M2M) communication is centered on the intelligent interaction of user equipment (UEs) without human intervention, which is the enabler for the Internet of Things (IoT) to achieve the envision of the “Internet of Everything” [1], [2]
To further resolve the pilot collision for the M2M communication in crowded asynchronous massive multiple-input multiple-output (MIMO) systems, we propose a novel random access scheme, where the base station (BS) employs a proposed estimation of signal parameters via rotational invariance technique enhanced (ESPRIT-E) method to estimate the effective timing offsets of UEs, and UEs judge whether it is detected in a distributed manner
Since the value of wk is very small in general and its impact can reasonably be neglected if the pilot contains only a few consecutive orthogonal frequency division multiplexing (OFDM) symbols [19], [20], we only consider the timing error θk = 2Dk/(cTs) where Dk is the distance from UE k to the BS, c = 3 × 108m/s is the speed of light, Ts = 1/(∆f NFFT) is the sampling period where NFFT is the number of subcarriers with frequency spacing ∆f
Summary
The machine-to-machine (M2M) communication is centered on the intelligent interaction of user equipment (UEs) without human intervention, which is the enabler for the Internet of Things (IoT) to achieve the envision of the “Internet of Everything” [1], [2]. Liu et al proposed a approximate message passing (AMP) based grant-free scheme to achieve the joint activity detection and CSI estimation for massive MIMO systems [13] This AMP-based grant-free random access scheme requires long pilot sequence to achieve better performance, resulting in heavy pilot overhead. These grant-free random access schemes considers the single pilot structure, and Jiang et al proposed to concatenate several multiple orthogonal sub-pilots into one pilot sequence, where different UEs are allocated different pilot sequences and the pilot sequence is utilized for activity detection and CSI estimation [14]. We utilize arg(d) to denote the phase of the complex d
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