Slepian–Wolf Coding Over Cooperative Relay Networks

In this paper, we examine and investigate the effects of noise-induced transmission errors on the performance of image transmission over cooperative relay networks with various error-correction capabilities. MAP decoder is used to decode the data sent across the cooperative network. First, the relationships between lengths of the code, peak signal-to-noise ratio, and signal-to-noise ratio are analyzed. Second, the comparison between the performances of different channel coding is introduced in conjunction with the set partitioning in hierarchical trees algorithm as a source code. The genetic algorithm, as an efficient optimization technique, is applied for solving the problem of optimal unequal error protection method to reduce the transmission rate and to improve the transmitted image quality. Many useful and significant results that are introduced in this paper can be used in the enhancement of image transmission over the cooperative networks. Compared to traditional methods, the suggested method is more practical for the transmission of images with high-quality via smart devices.

Cooperative communication combats the effects offadingwithoutthe need for multiple antennas.The cooperative networks use multiple distributed nodes that virtually behave like multiple antennas each having their own local oscillators. But the oscillators cause multiple Carrier Frequency Offsets (CFO), unknown channel gains and Multiple Timing Offsets (MTO). For a good performance of the system perfect synchronization is needed which is achieved by estimation and compensation of multiple offsets. Also, the coverage and capacity can be improved by employing intermediate nodes called relays within cooperative networks. These cooperative relay networks can perform in a better manner even when considering MCFOs, MTOs and unknown channel gains by having more computationally efficient decoders that can use Maximum Likelihood (ML) estimation subject to the Cramer-Rao Lower Bound (CRLB) on the variance of any impartial estimate. The simulation results show that frequency offset still exist after Amplify and Forward (AF) relaying. The performance of a conventional cooperative network seems to have improved with respect to Bit Error Rate of the system when an AF relay is hosted. The estimate of the frequency offset is chosen such that it gives the signal, a high probability of occurrence using ML estimator. In ML estimate, since the bias and variance is difficult to compute, a lower bound called the CRLB on the variance of any unbiased estimate is derived which is satisfied by the ML estimator.Keywords: AF, Cooperative Communication, CFO, ML Estimation and Compensation, OFDM

In this paper, we propose a joint resource allocation, routing, and connection admission control (CAC) scheme for uplink transmission in orthogonal frequency division multiple access (OFDMA) relay networks with cooperative relaying. For cooperative relaying, relay station can relay uplink data from mobile station (MS) to base station with cooperation of the MS using transmit diversity. Transmit diversity can be achieved by virtual MISO via distributed space---time coding. The proposed scheme jointly allocates OFDMA resources and selects path for each user with CAC to maximize the upink throughput of cooperative OFDMA relay networks. The basic OFDMA resource unit is considered as a resource element which is one subcarrier over one OFDMA symbol. An efficient multi-choice multi-dimensional knapsack (MMKP) algorithm is presented for the proposed scheme. The proposed MMKP algorithm provides a unified framework which is applicable to OFDMA networks with and without cooperative relaying. We evaluate the performance of the proposed scheme with and without cooperative relaying in a hilly terrain with heavy tree density by using OPNET-based simulation. We show that the cooperative relaying improve the uplink system throughput compared with non-cooperative relaying, and the proposed scheme outperforms the conventional link quality-based scheme in both cooperative and non-cooperative relay networks.

MIMO system makes full use of the space dimension, in the era of increasingly tense spectrum resources, which greatly improves the spectrum efficiency and is one of the future communication support technologies. At the same time, considering the high cost of direct communication between the two parties in a long distance, the relay communication mode has been paid more and more attention. In relay communication network, each node connected by relay has different security levels. In order to forward the information of all nodes, the relay node has the lowest security permission level. Therefore, it is meaningful to study the physical layer security problem in MIMO two-way relay system with relay as the eavesdropper. In view of the above situation, this paper proposes the physical layer security model of MIMO two-way relay cooperative communication network, designs a communication matching grouping algorithm with low complexity and a two-step carrier allocation optimization algorithm, which improves the total security capacity of the system. At the same time, theoretical analysis and simulation verify the effectiveness of the proposed algorithm.

Optimization scheme with pre-processing for cooperative relay multicast networks in cellular system

In a cooperative communication relay network, secure data transmission from source to the intended destination via relay nodes is an important issue. The eavesdropper or an adversary could tap the information from the link and hence maintaining secrecy is crucial. For confidential communication, we have taken into account the degree of trust, which would indeed help the source to select the best relay for forwarding data more efficiently and reliably without concerning on the eavesdropping attack. Also, unlike other works till date, we have developed duopoly game secure models to corroborate that the relay's profit gets higher with higher degree of trust in cooperative relay network. The utility of relays is evaluated for various duopoly-economic game modelling schemes and it is shown that there is decrease in the profit of relays with higher relay to eavesdropper SNR. We have demonstrated that the strategic variable choice as price or output in an oligopoly market theory, can dramatically impact the Nash outcome.

In this paper, a new relay selection scheme for decode-and-forward (DF) relay cooperative network with multiple antennas is proposed based on both channel state information (CSI) and transmission scheme by deriving the upper bound on the pairwise error probability (PEP) of the near-maximum-likelihood (near-ML) decoder. It is also proved that the proposed relay selection which selects m (1≤ m≤ N) relays from N relays achieves full diversity M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</sub> M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> +N M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</sub> min[M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</sub> , M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> ] regardless of the value of m in the DF relay network consisting of one source, one destination, and N relays with M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</sub> , M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> , and M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</sub> antennas, respectively. Through Monte Carlo simulation, the error correction performance of the proposed relay selection for various m is shown for the uncoded single-antenna, Alamouti coded, and multiple-input multiple-output (MIMO) DF relay networks.

Network coding is seen as a promising technique to improve network throughput. In this paper, network coding in cooperative relay networks and user cooperative networks is investigated and an optimized power allocation scheme is provided. By comparing with traditional relay forwarding in a simple two-user scenario, network coding shows a better system performance with a lower hardware cost and higher spectral efficiency, and this scenario can be extended to general multi-user environment without much cost.

In this study, we investigate the fundamental limits for time delay based location estimation in decode-andforward (DF) relaying strategy based cooperative relay networks considering multipath environments. The limits are presented by obtaining Cramer-Rao Lower Bounds (CRLBs) expressions. Simulations are performed to verify the CRLB expressions and show the effects of the node topology of the network, number of relay nodes, and number of multipath components (MPCs) on the location estimation accuracy of source node. According to the results, the placement of the relay nodes is very important to lower the location estimation error. Furthermore, using more relay nodes decreases the location estimation error, dramatically. Finally, processing more MPCs at the destination node is crucial to improve the estimation accuracy in the cooperative relay networks.

The outage behavior of decode-and-forward (DF) relaying protocol over an asynchronous cooperative network is examined when orthogonal frequency division multiplexing (OFDM) is used to combat synchronization error among the transmitting nodes. We consider non-orthogonal selection DF (NSDF) and orthogonal selection DF (OSDF) protocols, respectively, over a single relay and a two relay cooperative network and analyze the diversity multiplexing gain Tradeoff (DMT) in both scenarios. It is proved that asynchronous protocols provide diversity gains greater than or equal to the one of synchronous counterparts in the limit of code word length and throughout the range of multiplexing gain.

We study the following natural question: Which cryptographic primitives (if any) can be realized by functions with constant input locality, namely functions in which every bit of the input influences only a constant number of bits of the output? This continues the study of cryptography in low complexity classes. It was recently shown by Applebaum et al. (FOCS 2004) that, under standard cryptographic assumptions, most cryptographic primitives can be realized by functions with constant output locality, namely ones in which every bit of the output is influenced by a constant number of bits from the input. We (almost) characterize what cryptographic tasks can be performed with constant input locality. On the negative side, we show that primitives which require some form of non-malleability (such as digital signatures, message authentication, or non-malleable encryption) cannot be realized with constant input locality. On the positive side, assuming the intractability of certain problems from the domain of error correcting codes (namely, hardness of decoding a random binary linear code or the security of the McEliece cryptosystem), we obtain new constructions of one-way functions, pseudorandom generators, commitments, and semantically-secure public-key encryption schemes whose input locality is constant. Moreover, these constructions also enjoy constant output locality and thus they give rise to cryptographic hardware that has constant-depth, constant fan-in and constant fan-out. As a byproduct, we obtain a pseudorandom generator whose output and input locality are both optimal (namely, 3).

Conventional designs on two-way relay networks mainly focus on the spectral efficiency (SE) rather than energy efficiency (EE). In this paper, we consider a system where two source nodes communicate with each other via an amplify-and-forward (AF) relay node and study the power allocation schemes to maximize EE while ensuring a certain data rate. We propose an optimal energy-efficient power allocation algorithm based on iterative search technique. In addition, a closed-form suboptimal solution is derived with reduced complexity and negligible performance degradation. Numerical results show that the proposed schemes can achieve considerable EE improvement compared with conventional designs.

Optimal power allocation (OPA) schemes for amplify-and-forward (AAF) relay networks have been widely investigated in recent years, usually under the assumption of readily known channel state information (CSI). This paper proposes a semi-blind iterative relay node selection (SBIRS) scheme to carry out the OPA procedure when the CSI are entirely unknown at the destination. We first develop a semi-blindly weighted multiple-eigenvector (SBWMEV) solution for optimally allocating power among all the relay nodes in the network. Aided by the intrinsic salient feature of the SBWMEV eigenvector structure, we further propose an iterative relay selection algorithm to simplify the SBWMEV solution with enhanced performance. In an iterative relay node selection manner, the proposed SBIRS scheme is capable of potentially allocating more power to the relay nodes with better channel conditions. Simulations verify that the SBIRS schemes outperform the SBWMEV scheme in terms of throughput and outage probability.

In this paper, we investigate the performance of a cooperative relay network performing location estimation through time of arrival (TOA). We derive Cramer-Rao lower bound (CRLB) for the location estimates using the relay network. The analysis is extended to obtain average CRLB considering the signal fluctuations in both relay and direct links. The effects of the channel fading of both relay and direct links and amplification factor and location of the relay node on average CRLB are investigated. Simulation results show that the channel fading of both relay and direct links and amplification factor and location of relay node affect the accuracy of TOA based location estimation. ©2010 IEEE.

This paper investigates simple means of analyzing the error rate performance of a general q-ary Galois Field network coded detect-and-forward cooperative relay network with known relay error statistics at the destination. Equivalent relay channels are used in obtaining an approximate error rate of the relay network, from which the diversity order is found. Error rate analyses using equivalent relay channel models are shown to be closely matched with simulation results. Using the equivalent relay channels, low complexity receivers are developed whose performances are close to that of the optimal maximum likelihood receiver.