Abstract
For the uplink multicell massive multiple-input multiple-output (MIMO) block fading systems, a two-dimensional smoothed l0 channel estimation method (2D-SL0-CE) with the aid of virtual channel representation is firstly exploited in this paper, which can jointly estimate the desired multiuser channels of the target cell and the interference links from neighbor cells without inducing pilot contamination. Then, a 2D-SL0 signal detection method (2D-SL0-SD) with the aid of sparse decomposing and the modified 2D sl0 recovery algorithm is proposed, which can jointly decode M-ary phase-shift keying (MPSK) signal block for whole desired users. Moreover, an improved 2D-SL0-SD is also proposed to remove multiuser interference of neighbor cells in high SNR scenario. Simulation results show that the 2D-SL0-CE method can remove performance floor induced by pilot contamination and need less pilot overhead than the conventional least square (LS) method. When detecting QPSK signal blocks at 12 dB SNR, the 2D-SL0-SD method with perfect channel state information (CSI) can obtain 10−2 BER. Moreover, in the case of 8PSK signals, the 2D-SL0-SD joining with the 2D-SL0-CE can obtain 10−2 BER at 20 dB SNR.
Highlights
1 Introduction The high energy and spectrum efficiency of massive multiple-input multiple-output (MIMO) systems heavily build on the premise that the base stations (BS) obtain channel state information (CSI) with reasonable quality, which is generally estimated via pilot sequences [1]
I=1 where Ptr denotes the training signal-to-noise ratio (SNR), the rows of Xtir ∈ CK×Ttr are the pilot sequences of ith cell, and Ntjr is the noise with i.i.d. elements distributed as CN(0, 1)
Using the CSI estimated through the Two-dimensional smoothed l0 (2D-SL0)-CE, where each user applies random non-orthogonal pilot sequence with length being 32, the obtained bit error rate (BER) of 2D-SL0-SD at 15 dB SNR is slightly better than 10−2, which shows joint the 2D-SL0-CE with 2D-SL0-SD for channel estimation and decoding Quadrature phase-shift keying (QPSK) signals is a feasible scheme
Summary
The high energy and spectrum efficiency of massive multiple-input multiple-output (MIMO) systems heavily build on the premise that the base stations (BS) obtain channel state information (CSI) with reasonable quality, which is generally estimated via pilot sequences [1]. The multiuser channel estimation problem and the multiuser signal decoding problem in uplink massive MIMO systems are modelled as two-dimensional sparse signal recovery problems in compressed sensing, respectively. We propose a channel estimation method named as 2D-SL0-CE applying the two-dimensional smoothed l0-norm compressed sensing recovery algorithm [37, 38], which are able to jointly estimate multiuser CSI. In a block fading channel, the training signal received at the jth BS becomes: L. i=1 where Ptr denotes the training signal-to-noise ratio (SNR), the rows of Xtir ∈ CK×Ttr are the pilot sequences of ith cell, and Ntjr is the noise with i.i.d. elements distributed as CN(0, 1). Such ruler requires that the elements of s in (12) have the same modulus
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