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In this article, a novel low-complexity block-processing sparse system estimation method, based on least squares (LS), ℓ1-norm minimization and support shrinkage, is proposed. The proposed method can be seen as a counterpart for the Least Absolute Shrinkage and Selection Operator (LASSO), in the sense that the proposed method aims to find the vector that minimizes its ℓ1-norm subject to a maximum...
An adaptive delay-tolerant distributed space-time coding (DSTC) scheme with feedback is proposed for two-hop cooperative multiple-input multiple-output (MIMO) networks using an amplify-and-forward strategy and opportunistic relaying algorithms. Maximum likelihood receivers and adjustable code matrices are considered subject to a power constraint. In the proposed delay-tolerant DSTC scheme, an adjustable...
In this paper, we propose a new detection technique for multiuser multiple-input multiple-output (MU-MIMO) systems. The proposed scheme combines a lattice reduction (LR) transformation, which makes the channel matrix nearly orthogonal, and then employs a multi-branch (MB) technique with successive interference cancellation (SIC). A single LR transformation is required for the receive filters of all...
We present reduced-rank widely linear precoding algorithms for Massive MIMO systems with I/Q imbalance (IQI). With a large number of transmit antennas, the imperfection I/Q branches at the transmitter has a significant impact on the downlink performance. We develop linear precoding techniques using an equivalent real-valued model to mitigate IQI and multiuser interference. In order to reduce the computational...
In this work, we propose a cross-layer design strategy based on a joint successive interference cancellation (SIC) detection technique and a multi-relay selection algorithm for the uplink of cooperative direct-sequence code-division multiple access (DS-CDMA) systems. We devise a low-cost greedy list-based SIC (GL-SIC) strategy with RAKE receivers as the front-end that can approach the maximum likelihood...
This paper presents a low-complexity robust data-dependent dimensionality reduction based on a modified joint iterative optimization (MJIO) algorithm for reduced-rank beamforming and steering vector estimation. The proposed robust optimization procedure jointly adjusts the parameters of a rank-reduction matrix and an adaptive beamformer. The optimized rank-reduction matrix projects the received signal...
This paper presents new dynamic topology adaptation strategies for distributed estimation in smart grids. A dynamic exhaustive search-based topology adaptation algorithm and a dynamic sparsity-inspired topology adaptation algorithm, which can exploit the topology of smart grids with poor-quality links and obtain performance gains, are proposed. An optimized combining rule, named the Hastings rule,...
In this work, we propose a minimum mean squared error (MMSE) robust base station (BS) precoding strategy based on switched relaying (SR) processing and limited transmission of side information for interference suppression in the downlink of multiuser multiple-input multiple-output (MIMO) relay systems. The BS and the MIMO relay station (RS) are both equipped with a codebook of interleaving matrices...
In this work, we propose a low-complexity adaptive transceiver algorithm for the K-pair multiple-input multiple-output (MIMO) interference channels. The proposed algorithm is based on the joint optimization of transmit and receive vectors using the constrained constant modulus (CCM) criterion. We firstly derive CCM-based expressions for the transmit and receiver vectors. Then, we develop recursive...
Generalised Quasi-Cyclic Root-Check LDPC codes based on Progressive Edge Growth (PEG) techniques for block-fading channels are proposed. The proposed Root-Check LDPC codes are suitable for channels under F= 3, 4 independent fadings per codeword which is a scenario that has not been previously considered. A generalised Quasi-Cyclic Root-Check structure is devised for F= 3, 4 independent fadings. The...
In this paper, we consider a multihop wireless sensor network (WSN) with multiple relay nodes for each hop where the amplify-and-forward (AF) scheme is employed. We present a strategy to jointly design the linear receiver and the power allocation parameters via an alternating optimization approach that maximizes the sum-rate of the WSN. We derive constrained maximum sum-rate (MSR) expressions along...
In this paper, cross-layer design methods are proposed for jointly detecting data streams and dynamically allocating power within a multiple-input multiple-output two-phase cooperative wireless communication system operating in a spatial multiplexing configuration and with single and multiple decode-and-forward (DF) relays. The proposed joint detection and power allocation schemes employ a maximum...
An adaptive iterative decision multi-feedback detection algorithm with constellation constraints is proposed for multiuser multi-cantenna systems. An enhanced detection and interference cancellation is performed by introducing multiple constellation points as decision candidates. A complexity reduction strategy is developed to avoid redundant processing with reliable decisions along with an adaptive...
In this work a low-complexity strategy for accelerating the convergence of convex combinations of adaptive filters is proposed. The idea is based on an instantaneous transfer of coefficients from a fast adaptive filter to a slow adaptive filter, which is performed according to a pre-defined window length. A theoretical model that is capable of predicting the excess mean squared error (EMSE) of the...
In this work, we propose a low-complexity variable forgetting factor (VFF) mechanism for blind adaptive constrained constant modulus (CCM) recursive least square (RLS) algorithms applied to linear interference suppression in direct-sequence code division multiple access (DS-CDMA) systems. The proposed VFF mechanism employs an updated component relating to the time average of the constant modulus (CM)...
An adaptive joint power allocation (JPA) and linear receiver design algorithm using the minimum bit error rate (MBER) criterion for a cooperative Multiple-Input Multiple-Output (MIMO) network is proposed. The system employs multiple relays with Distributed Space-Time Coding (DSTC) schemes and an Amplify-and-Forward (AF) strategy. It is designed according to a joint constrained optimization algorithm...
A novel cooperative interference mitigation strategy for an uplink cellular network with high frequency reuse factor is proposed in this paper. The cooperative base stations iteratively exchange their information among the neighbours while performing distributed signal processing. The base stations improve the estimate of the desired signal with each iteration and the exchanged information is used...
We propose a non-data-aided adaptive beamforming algorithm based on Widely Linear (WL) processing techniques and the Auxiliary Vector Filtering (AVF) algorithm for non-circular signals, where only the steering vector of the desired user is known. The proposed Widely Linear Auxiliary Vector Filtering (WL-AVF) algorithm recursively updates the filter weights by a sequence of auxiliary vectors that are...
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