| CPC H04B 7/0413 (2013.01) [H04L 25/0204 (2013.01); H04L 25/022 (2013.01); H04L 25/024 (2013.01)] | 7 Claims |

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1. An asymmetric massive MIMO (Multiple Input Multiple Output) channel estimation method based on a co-prime array, comprising:
S1: establishing an uplink and downlink asymmetric massive MIMO system based on the co-prime array, wherein the uplink and downlink asymmetric massive MIMO system comprises a base station provided with ultra-large-scale antennas and users, the number of users is K, each user has a single antenna of K antennas, the number of the ultra-large-scale antennas of the base station is M, all the ultra-large-scale antennas of the base station have transmitting radio-frequency links, only N receiving radio-frequency links are available to be connected to N antennas within the ultra-large-scale antennas to receive uplink signals, and the users communicate with the base station by means of Q frequency points; M=mn+1, and N=m+n−1, where m<n, and m and n are co-prime; selecting uplink receiving antennas according to the co-prime array, and connecting the selected uplink receiving antennas to the receiving radio-frequency links;
S2: receiving and estimating, by the base station, uplink channel information of part of the ultra-large-scale antennas, and constructing, after the uplink channel information is transformed to a frequency domain and is screened and rearranged, a virtual linear uniform array;
S3: stretching virtual array information in the virtual linear uniform array to construct an observation matrix, then according to the observation matrix, constructing a group least absolute shrinkage and selection operator based on compressive sensing by means of spatial sparse characteristics to estimate a direction of arrival;
S4: reconstructing a partial array manifold matrix according to the estimated direction of arrival, and estimating path gain according to instantaneous channel information observed in the frequency domain later; and
S5: reconstructing a complete uplink channel according to the estimated path gain and direction of arrival, and reconstructing a downlink channel based on reciprocity.
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