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Machine-type communication services in mobile cellular systems are currently evolving with an aim to efficiently address a massive-scale user access to the system. One of the key problems in this respect is to efficiently identify active users in order to allocate them resources for the subsequent transmissions. In this paper, we examine two recently suggested approaches for user activity detection:...
Sparse regression codes (SPARCs) are a recent class of codes for reliable communication over the AWGN channel at rates approaching the channel capacity. Approximate message passing (AMP) decoding, a computationally efficient technique for decoding SPARCs, has been proven to be asymptotically capacity-achieving for the AWGN channel. In this paper, we refine the asymptotic results by deriving a large...
Three potential interference cancellation schemes are compared for the application to a non-orthogonal multiple access communication system. One is the conventional hard successive interference cancellation (SIC) scheme based on independent single-user decodings. The other two, proposed in this paper, are a soft-in soft-out parallel interference cancellation (SISO-PIC) and a hybrid interference cancellation...
Sparse superposition codes were recently introduced by Barron and Joseph for reliable communication over the AWGN channel at rates approaching the channel capacity. In this code, the codewords are sparse linear combinations of columns of a design matrix. In this paper, we propose an approximate message passing decoder for sparse superposition codes. The complexity of the decoder scales linearly with...
Cell-edge users inevitably experience strong interference from adjacent cells, and consequently suffer from performance degradation. Currently, Han-Kobayashi (HK) rate splitting scheme is viewed as the best strategy to cancel the interference and improve the performance. As a special superposition coding scheme, the HK rate splitting scheme has been shown to potentially achieve the channel capacity...
Hybrid automatic repeat request (HARQ) is a well-known technique for improving system throughput and link performance of wireless communication systems, including cooperative communication systems. In this paper, we exploit the limited feedback applied to the two-source turbo coded cooperation scheme to define a particular cooperative HARQ protocol, called two-level HARQ, where the decision on retransmission...
In this paper we investigate the effect of power allocation on the performance of the Distributed Turbo Product Code (DTPC) system. We study the error propagation on distributed coding systems when the relay makes erroneous decisions and present a simple power allocation method to alleviate the effect of relay decoding errors on the iterative decoding at the destination. We validate this method with...
This paper proposes an improved scheme for cooperative transmit diversity, which applies the Euclidean superposition of modulated signals. Assuming two sources cooperate in transmitting information to a single destination, each source divides its transmit power between locally generated information and relayed information that originated at the other source. This leads to an encoding scheme in which...
A multi-dimensional extrinsic information transfer analysis of multi-power level multi-user detectors is proposed as a tool to better understand the convergence behavior of iterative decoding schemes. We develop a K dimensional EXIT chart in order to analyze a system with K power levels. We state a conjecture that predicts the convergence point of the system. We show through simulation our analysis...
Fountain codes are a class of recently proposed efficient erasure error-control codes. However, the original design of fountain codes, despite being highly efficient for erasure channels, has very poor progressive decoding performance. The purpose of this paper is to design and optimize unequal error protection (UEP) fountain codes to maximize the throughput of multimedia communication systems while...
In this paper, we develop a rate allocation scheme for interleave-division multiple-access (IDMA) systems with iterative decoding. We use a fully-analytical approach to predict the performance of the scheme and propose a modified linear programming method to design the rate profile. Numerical results show that with just repetition coding and rate allocation, the performance of the scheme is only about...
Irregular LDPC codes can have capacity-approaching performance with an iterative BP decoder under AWGN channel with BPSK modulation. Generally in BPSK modulation, every bit within the block has the same power. In this paper, we investigate unequal power allocation (UPA) using BPSK modulation for irregular binary LDPC codes. We show that constant power modulation need not lead to the best performance...
In this contribution we jointly optimize the number of activated MIMO layers and the number of bits per symbol along with the appropriate allocation of the transmit power under the constraint of a given fixed data throughput and integrity. However, non-frequency selective MIMO links have attracted a lot of research and have reached a state of maturity. By contrast, frequency selective MIMO links require...
This paper considers a novel approach to multicarrier orthogonal frequency division multiplexing-based interleave-division multiple-access (OFDM-IDMA) that facilitates both channel estimation and multi-user detection. Specifically, users employ interleavers based upon their channel state information (CSI) to optimize pilot symbol locations, instead of random interleavers as in conventional IDMA. Two...
We propose a new superposition modulation-based cooperative diversity scheme and investigate receivers with iterative detection and decoding for the scheme, where we focus on a interference cancellation (IC) detector. We analyze the bit-error-probability (BEP) of the scheme and find the optimal power allocation. Simulation results are shown to be very close to the analytical results for a wide range...
The Bell labs layered space-time (BLAST) architecture pioneered by Foschini was found to achieve high spectral efficiency with moderate complexity. However, the redundancy in error correcting codes in BLAST receiver is not used in detection improvement, as detection and decoding are carried out separately. In this paper, we investigate a new approach for improved performance of BLAST based on multi-stage...
Performances of BICM-ID systems strongly depend on the matching between mapping rule and code structure. This paper proposes a combined use of extended mapping (EM) and simple repetition code. Even with such a simple structure, turbo cliff happens at a value range of signal-to-noise power ratio (SNR) 1~2 dB to the Shannon limit. This paper then introduces check node as well as irregular node degree...
Interleave-division multiple-access (IDMA) has recently been proposed as a multiuser scheme where users are separated by unique interleaver sequences. When used with low-complexity iterative receivers, IDMA has been shown to outperform coded CDMA. In this paper we consider a multi-rate system where high data- rate transmitters are constructed by combining several IDMA layers together, and transmitting...
In this paper, we study a distributed resource control problem achieving fairness and information theoretic capacity in an OFDMA system. For practicality, we consider an OFDMA system with incomplete information. The information theoretic MAC capacity region is known to be achieved by successive decoding schemes. Therefore, the problem can be formulated as a stackelberg optimization problem. As a solution...
In this contribution we present a decentralized power allocation algorithm for the uplink interleave division multiple access (IDMA) channel. Within the proposed optimal strategy for power allocation, each user aims at selfishly maximizing its own utility function. An iterative chip-by-chip (CBC) decoder at the receiver and a rational selfish behavior of all the users according to a classical game-theoretical...
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