This work proposes a novel linear programming approach for the joint detection and decoding of LDPC-based space-time (ST) coded signals in multi-antenna orthogonal frequency division multiplexing (OFDM) systems. While...
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This work proposes a novel linear programming approach for the joint detection and decoding of LDPC-based space-time (ST) coded signals in multi-antenna orthogonal frequency division multiplexing (OFDM) systems. While traditional receivers typically decouple the detection and decoding processes as two disjunctive blocks or require iterative turbo exchange of extrinsic information between the soft detector and decoder, we formulate a joint linear program (LP) by exploiting the constraints imposed on the data symbols, training symbols, noise subspace as well as channel code. In consideration of the vast amount of LDPC parity check inequalities, we further present an adaptive procedure to significantly reduce the complexity of the joint LP receiver. Our LP-based receivers outperform existing receivers with substantial performance gains. Moreover, the proposed joint LP receiver demonstrates strong robustness when pilot symbols are sparsely arranged on subcarriers.
In this paper, we present a novel approach to perform joint detection and decoding for spatial multiplexing multiple-input multiple-output (MIMO) systems which utilize convolutional codes. The bit error rate (BER) per...
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In this paper, we present a novel approach to perform joint detection and decoding for spatial multiplexing multiple-input multiple-output (MIMO) systems which utilize convolutional codes. The bit error rate (BER) performance of the proposed approach is significantly better than that of systems which utilize separate detection and decoding blocks. Formal algorithms with two possible system setups are presented and their performance documented. In particular, for a reference 4 x 4, 16-QAM system using a rate 1/2 convolutional code with generator polynomial [247, 371] and a constraint length of 8, improvements in signal-to-noise ratio (SNR) of 2.5 dB and 3 dB are achieved over conventional soft decoding at a BER of 10(-5). The proof of concept VLSI architecture for one algorithm is provided and a novel way to reduce memory usage is demonstrated. Results indicate that better performance over conventional systems is achievable with comparable hardware complexity. The proposed design was synthesized and layout with 65-nm CMOS technology at 181-MHz clock frequency. An average throughput of 216.9 Mbps at a SNR of 13 dB with area equivalent to 553 Kgates was achieved.
Due to its outstanding spectral efficiency,multipleinput and multiple-output(MIMO) technology has been developed and drawn increasing attentions for recent *** balancing complexity and performance,K-best algorithm has...
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ISBN:
(纸本)9781509066261;9781509066254
Due to its outstanding spectral efficiency,multipleinput and multiple-output(MIMO) technology has been developed and drawn increasing attentions for recent *** balancing complexity and performance,K-best algorithm has become one of the most favorable MIMO *** this paper,a joint detection and decoding(JDD) for non-binary LDPC(NB-LDPC) coded MIMO systems has been proposed with better performance compared to the existing K-best detection,which prunes the tree-search with NB-LDPC coding *** results have demonstrated that the JDD system with8 × 8 MIMO and GF(4)(8,2) NB-LDPC code can achieve up to4 d B gain at BER = 2 × 10-2 compared to the state-of-the-art(SOA) *** architecture and schedule analysis have shown the advantages and feasibility of proposed JDD.
Sparse code multiple access (SCMA) is a research hotspot in recent years. In this paper, we proposed a joint SCMA detection and Turbo decoding (JDD) scheme for the SCMA system. The proposed method integrates the messa...
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ISBN:
(纸本)9781509024827
Sparse code multiple access (SCMA) is a research hotspot in recent years. In this paper, we proposed a joint SCMA detection and Turbo decoding (JDD) scheme for the SCMA system. The proposed method integrates the message passing between SCMA detector and turbo decoder into the factor graph of the SCMA detector to construct a joint factor graph. Simulation results show the JDD scheme has 1.6 dB performance gain compared to the iterative detection and decoding (IDD) scheme. Moreover, it has only 0.2 dB performance loss compared to the single user QPSK system. To further reduce the computational complexity of the JDD scheme, we implement the JDD scheme in the logarithm domain (LOG-JDD) with the same performance compared with the IDD scheme. A technology that can improve the convergence is used to improve the bit error rate (BER) performance. Simulation results show that a suitable damping factor can obtain about 1dB performance gain compared with the IDD scheme.
We develop a linear programming based approach for the joint detection and decoding of LDPC coded distributed space-time signaling transmitted in a wireless relay network. Traditional receivers typically decouple the ...
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ISBN:
(纸本)9781479928934
We develop a linear programming based approach for the joint detection and decoding of LDPC coded distributed space-time signaling transmitted in a wireless relay network. Traditional receivers typically decouple the detection and decoding processes as two separate blocks or require iterative turbo exchange of extrinsic information between the soft detector and decoder. We exploit the constraints imposed on the channel input signals and jointly consider the training symbols as well as the LDPC code information by formulating a unified linear programming (LP) receiver. Moreover, in consideration of the vast amount of LDPC parity check inequalities, we present an adaptive procedure to significantly reduce the complexity of the proposed LP receiver.
Sparse-code multiple-access (SCMA) is a novel multiplexing method to increase the capacity of wireless communication systems. By giving users non-orthogonal codebook with few non-zero entries, the SCMA approach can hi...
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ISBN:
(纸本)9781538620625
Sparse-code multiple-access (SCMA) is a novel multiplexing method to increase the capacity of wireless communication systems. By giving users non-orthogonal codebook with few non-zero entries, the SCMA approach can highly improve the spectral efficiency, compared with traditional orthogonal ones such as CDMA, with tolerable detection complexity. Therefore, it has been considered as an option for 5G air-interface technique. Also essential in 5G, polar code has already been adopted by 5G eMBB control channel, for its capacity-achieving capability. In this work, a joint detection and decoding (JDD) method of polar-coded SCMA system is proposed for the first time, which can highly improve the performance of the polar-SCMA systems. By merging two factor graphs together, the intrinsic messages can be exchanged iteratively to help the likelihood messages converge. Numerical results have shown that, compared to separated detection and decoding (SDD), JDD can achieve remarkable performance gain little complexity overhead. Hardware architecture is also presented in this paper to demonstrate the feasibility of the proposed JDD scheme.
Optimal receivers recovering signals transmitted across noisy communication channels employ a maximum-likelihood (ML) criterion to minimize the probability of error. The problem of finding the most likely transmitted ...
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Optimal receivers recovering signals transmitted across noisy communication channels employ a maximum-likelihood (ML) criterion to minimize the probability of error. The problem of finding the most likely transmitted symbol is often equivalent to finding the closest lattice point to a given point and is known to be NP-hard. In systems that employ error-correcting coding for data protection, the symbol space forms a sparse lattice, where the sparsity structure is determined by the code. In such systems, NIL data recovery may be geometrically interpreted as a search for the closest point in the sparse lattice. In this paper, motivated by the idea of the "sphere decoding" algorithm of Fincke and Pohst, we propose an algorithm that finds the closest point in the sparse lattice to the given vector. This given vector is not arbitrary, but rather is an unknown sparse lattice point that has been perturbed by an additive noise vector whose statistical properties are known. The complexity of the proposed algorithm is thus a random variable. We study its expected value, averaged over the noise and over the lattice. For binary linear block codes, we find the expected complexity in closed form. Simulation results indicate significant performance gains over systems employing separate detection and decoding, yet are obtained at a complexity that is practically feasible over a wide range of system parameters.
We design a low-density parity-check (LDPC) coded multi-user massive multiple-input multiple-output (MIMO) system to achieve a high error correcting capability with a fast convergence speed of iterative joint detectio...
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We design a low-density parity-check (LDPC) coded multi-user massive multiple-input multiple-output (MIMO) system to achieve a high error correcting capability with a fast convergence speed of iterative joint detection and decoding (JDD) process employing a low-complexity detection. Minimum mean squared error detection with parallel interference cancellation (MMSE-PIC) and its variations are considered as low-complexity linear detection algorithms. We provide a factor graph representation of LDPC coded multi-user massive MIMO system using JDD algorithm employing MMSE-PIC detection, and we formulate updating rules of messages flowing in the JDD process. We propose a practical and efficient tool for analyzing the extrinsic information transfer (EXIT) characteristics of messages exchanged between detector and decoder, based on which LDPC codes and JDD strategy are jointly designed to result in a low bit error rate (BER) and a fast convergence speed of JDD mechanism. It is observed that the error correcting capability and JDD convergence behavior predicted by the proposed analysis tool match well the actual performances obtained by simulations. It is also observed that LDPC coded multi-user massive MIMO system employing LDPC codes and JDD strategy designed optimally by the proposed EXIT analysis tool achieves a lower BER with a faster convergence speed.
Soft iterative detection and decoding techniques have been shown to achieve near-capacity performance in multiple antenna systems. In most cases, obtaining optimal soft information in a joint detection and decoding al...
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Soft iterative detection and decoding techniques have been shown to achieve near-capacity performance in multiple antenna systems. In most cases, obtaining optimal soft information in a joint detection and decoding algorithm by marginalizing over the entire observation space is prohibitively complex. In this paper, an improved scheme adaptable to various list-type detectors providing superior performance is proposed.
Soft iterative detection and decoding techniques have been shown to be able to achieve near-capacity performance in multiple-antenna systems. To obtain the optimal soft information by marginalizing over the entire obs...
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Soft iterative detection and decoding techniques have been shown to be able to achieve near-capacity performance in multiple-antenna systems. To obtain the optimal soft information by marginalizing over the entire observation space is intractable: one must resort to suboptimal methods to implement such receivers. Although list-type detectors such as those founded upon the sphere decoding algorithm provide outstanding error performance, issues such as the optimal initial sphere radius, optimal radius update strategy, and their highly variable computational complexity are still unresolved. In this paper, a new detection scheme is proposed addressing the above issues. Our simulation results show that by sacrificing less than 2 dB at error rate of 10(-5), we are able to gain up to 38.6% complexity reduction as well as a detector structure that is more suitable for practical system implementation.
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