Download or read book Enhancing the Performance of Relay Networks with Network Coding written by Scott Harold Melvin and published by . This book was released on 2012 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT CONT'D : The motivation is that to improve the performance of communication systems, relay nodes will need to perform more intelligent processing of data units than traditional routing. The results presented in this work are applicable to both wireless and wired networks with real-time traffic which exist in such systems ranging from cellular and ad-hoc networks to fixed optical networks.
Download or read book Delay Performance of Hybrid Network Coding Based on Cooperative Relay Networks written by 歐恩廷 and published by . This book was released on 2010 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Network Coding in Relay Networks written by Eduardo Alban and published by VDM Publishing. This book was released on 2008 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transmission over wireless networks presents multiple technical challenges due to noise, interference, fading, power constraints and bandwidth limitation. Different solutions have been propposed to overcome these issues and some of them are treated here. Cooperative diversity has been proposed as an implementation for networks where terminals are restricted to using physical arrays; this technique implements space diversity by creating virtual antennas arrays with cooperating nodes in order to combat multipath fading. Network Coding recently has been presented as a technique to increase the throughput in multicast networks. Most of the work done on the topic considers an error free transmission and few works have taken into account the errors due to the nature of the wireless channel. This thesis proposes the use of network coding over some scenarios in relay networks, in order to obtain diversity. It also addresses some cooperative protocols and their performance in terms of bit error rate. Reliability criteria based on channel information are established for a practical network implementation. In short, we propose a scheme for a wireless network using ideas based on network coding.
Download or read book Performance Analysis of Relay Network Using Partial Compute and Forward Scheme and Physical layer Network Coding written by Navyatha Gavvala and published by . This book was released on 2011 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, the bit error rate (BER) performance of a relay network using both a partial compute-and-forward (PCF) strategy and a decode-and-forward (DF) strategy is studied. The system model considered is a relay network, which has multiple sources, multiple relay nodes, and one destination. First, in this thesis, BER performance of the relay network is analyzed using a decode-and-forward strategy. Second, another approach, called a partial compute-and-forward strategy, is proposed. The key idea here is to add dither, to the transmitted messages, then encode and forward the messages to the relay nodes like lattice codes. Once the relay nodes receive the linear combination of transmitted signals, they first remove the dithered signal and then map it to a linear combination of the transmitted message. This linear combination of the message is forwarded to the destination under a power constraint at the relay. Results show that the BER performance of the partial compute-and-forward strategy is better than the decode-and-forward strategy applied at the relay nodes. This thesis also analyzes the BER performance of a four-user physical-layer network coding (PNC), the implementation of which enhances the throughput and routing capabilities of a relay network.
Download or read book Parameter Estimation and Tracking in Physical Layer Network Coding written by Manish Jain and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently, there has been a growing interest in improving the performance of the wireless relay networks through the use of Physical Layer Network Coding (PLNC) techniques. The physical layer network coding technique allows two terminals to transmit simultaneously to a relay node and decode the modulo-2 sum of the transmitted bits at the relay. This technique considerably improves performance over Digital Network Coding technique. In this thesis, we will present an algorithm for joint decoding of the modulo-2 sum of bits transmitted from two unsynchronized transmitters at the relay. We shall also address the problems that arise when boundaries of the signals do not align with each other and when the channel parameters are slowly varying and are unknown to the receiver at the relay node. Our approach will first jointly estimate the timing o sets and fading gains of both signals using a known pilot sequence sent by both transmitters in the beginning of the packet and then perform Maximum Likelihood detection of data using a state-based Viterbi decoding scheme that takes into account the timing o sets between the interfering signals. We shall present an algorithm for simultaneously tracking the amplitude and phase of slowly varying wireless channel that will work in conjunction our Maximum Likelihood detection algorithm. Finally, we shall provide extension of our receiver to support antenna diversity. Our results show that the proposed detection algorithm works reasonably well, even with the assumption of timing misalignment. We also demonstrate that the performance of the algorithm is not degraded by amplitude and/or phase mismatch between the users. We further show that the performance of the channel tracking algorithm is close to the ideal case i.e. when the channel estimates are perfectly known. Finally, we demonstrate the performance boost provided by the receiver antenna diversity.
Download or read book Collaborative Coding Techniques with Analog Network Coding in Wireless Y Channel Relay Networks written by Issa Al-Fanek and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design of Network Coding Schemes in Wireless Networks written by Zihuai Lin and published by CRC Press. This book was released on 2022-06-23 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a consolidated view of the various network coding techniques to be implemented at the design of the wireless networks for improving its overall performance. It covers multiple sources communicating with multiple destinations via a common relay followed by network coded modulation schemes for multiple access relay channels. Performance of the distributed systems based on distributed convolutional codes with network coded modulation is covered including a two-way relay channel (TWRC). Two MIF protocols are proposed including derivation of signal-to-noise ratio (SNR) and development of threshold of the channel conditions of both. Features: Systematically investigates coding and modulation for wireless relay networks. Discusses how to apply lattice codes in implementing lossless communications and lossy source coding over a network. Focusses on theoretical approach for performance optimization. Includes various network coding strategies for different networks. Reviews relevant existing and ongoing research in optimization along with practical code design. This book aims at Researchers, Professionals and Graduate students in Networking, Communications, Information, Coding Theory, Theoretical Computer Science, Performance Analysis and Resource Optimization, Applied Discrete Mathematics, and Applied Probability.
Download or read book Security in Network Coding written by Peng Zhang and published by Springer. This book was released on 2016-05-26 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers a series of security and privacy issues in network coding, and introduces three concrete mechanisms to address them. These mechanisms leverage traditional cryptographic primitives and anonymous protocols, and are redesigned to fit into the new framework of network coding. These three mechanisms are MacSig, a new message authentication method for network-coded systems; P-Coding, a new encryption scheme to secure network-coding-based transmissions; and ANOC, a new anonymous routing protocol that seamlessly integrates anonymous routing with network coding. Along with these three mechanisms, the authors provide a review of network coding's benefits, applications, and security problems. Also included is a detailed overview of security issues in the field, with an explanation of how the security issues differ from those in traditional settings. While network coding can help improve network performance, the adoption of network coding can be greatly limited unless security and privacy threats are addressed. Designed for researchers and professionals, Security in Network Coding explores major challenges in network coding and offers practical solutions. Advanced-level students studying networking or system security will also find the content valuable.
Download or read book Joint Network written by Xuan Thang Vu and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Network coding (NC) has gained much research attention as a potential candidate to solve the demand for higher spectral efficiency of modern wireless communications. Many research papers have investigated the performance of NC-aided networks such as throughput and outage capacity. However, the analysis of NC in practical systems where NC is combined with other techniques such as channel coding is still immature to fully understand its potential performance. In this thesis, we aim to design high performance receivers and analyze its performance for network-coded cooperative networks in practical scenarios.Firstly, we propose two Iterative Network/Channel Decoding (INCD) algorithms for the Multiple-Access Relay Channel (MARC) with two notable relaying schemes named Decode-and-Forward (DF) and Demodulate-and-Forward (DMF). The INCD algorithm operates based on turbo-like decoding methods and reduces the impact of the error propagation problem with the aid of a channel-aware receiver design. Both perfect Channel State Information (CSI) and imperfect CSI at the receiver side are investigated. We propose a practical method that forwards the quantized version of the relay decoding errors to the destination. It is shown that the proposed algorithms achieve full diversity gain and significantly outperforms solutions which do not take care of error propagation. We also show that the number of pilot symbols affects only the coding gain but has a negligible impact on the diversity order, while the quantization level affects both the diversity and coding gain.Secondly, we propose a Near Optimal Joint Network/Channel Decoding (NOJNCD) algorithm for the MARC that allows to analyze the system Bit Error Rate (BER). The NOJNCD algorithm performs network decoding and channel decoding in one decoding step of the super code, which comprises of all trellis states of individual code at the sources via NC. Furthermore, NC combined with Relay Selection (RS) is considered and the achievable diversity order is studied with the aid of outage analysis. We analytically show that Single Relay Selection (SRS) always achieves a diversity order two and Multiple Relay Selection (MRS) can achieve full diversity gain only when the number of selected relays exceeds the number of the sources.Last but not least, we propose a so-called partial relaying protocol to improve the spectral efficiency for channel coding assisted relay networks. Closed-form expression of the BER and the system diversity order are computed for partial relaying. We show, by analysis and simulations, that with a proper Convolutional Code (CC), partial relaying can achieve full diversity gain and same coding gain as the classical (full) relaying protocol in finite signal-to-noise ratio region while it obtains a better spectrum usage. Moreover, we propose a new protocol based on partial relaying in opportunistic relaying cooperative networks and show that this protocol significantly outperforms the NC-based cooperation in some circumstances.
Download or read book Design and Implementation of Physical Layer Network Coding Protocols written by Dumezie K. Maduike and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: There has recently been growing interest in using physical layer network coding techniques to facilitate information transfer in wireless relay networks. The physical layer network coding technique takes advantage of the additive nature of wireless signals by allowing two terminals to transmit simultaneously to the relay node. This technique has several performance benefits, such as improving utilization and throughput of wireless channels and reducing delay. In this thesis, we present an algorithm for joint decoding of two unsynchronized transmitters to a modulo-2 sum of their transmitted messages. We address the problems that arise when the boundaries of the signals do not align with each other and when their phases are not identical. Our approach uses a state-based Viterbi decoding scheme that takes into account the timing offsets between the interfering signals. As a future research plan, we plan to utilize software-defined radios (SDRs) as a testbed to show the practicality of our approach and to verify its performance. Our simulation studies show that the decoder performs well with the only degrading factor being the noise level in the channel.
Download or read book Physical layer Network Coding in Multi way Relay Channels written by Hao Li and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Physical-layer network coding (PNC) is an attractive approach to increasing the network throughput by exploiting the broadcast nature of wireless channels. This thesis focuses on the application of PNC in a class of wireless networks known as multi-way relay channels (MRWC), where multiple users share information through a single relay. The primary objective of the thesis is to develop new uplink and downlink schemes for PNC in MWRC, with the main focus on signal detection and power allocation. First, we propose a novel signal detection scheme for PNC in MWRC from the perspective of sequential multi-user detection. The extraction of the network codes from the superimposed user signals at the relay node is formulated as an under-determined linear system. To solve this problem with low decoding complexity, the proposed method combines successive interference cancellation (SIC) with Babai estimation for regularized integer least squares (ILS). We develop a power allocation scheme to enhance the performance of both SIC and ILS steps, and discuss an optimal user pairing strategy based on the average decoding error probability. The performance of the proposed method improves the relay's capability of extracting network codes from multiple superimposed user signals, as demonstrated by the numerical results. Next, we address the design of power allocation schemes for PNC in downlink MWRC. The power allocation is formulated as a constrained optimization problem, where the aim is to maximize the probability of successfully decoding a chain of network codes, so-called success probability, under a total power constraint when using Babai estimation for signal detection. Three aggregate measures of success probability are considered over the participating user terminals, i.e., arithmetic mean, geometric mean, and maximin, and the solutions are obtained based on the concavity of the related problems. Results demonstrate the effectiveness of the proposed schemes in improving the success probability in the reception of a chain of network codes. Finally, we propose a new power allocation scheme based on the success probability of SIC detection for PNC in uplink MWRC. We develop a generalized expression for the closed-form success probability of the SIC detection at the relay in the case of pulse-amplitude modulation (PAM). A constraint optimization is formulated over this probability subject to the transmit power constraints at the user terminals. We develop an evolutionary particle swarm optimization (PSO) algorithm to solve the problem, whose cost function is relatively complex and not necessarily concave. Results show that the proposed method can improve the quality of network code extraction at the relay"--
Download or read book Network Coding written by Mohammad Matin and published by BoD – Books on Demand. This book was released on 2018-08-22 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: Network coding is an elegant and novel technique that allows nodes in the network to perform coding operations at the packet level. In particular, network coding represents a powerful approach to protect data from losses due to link disconnections and can also exploit the combination of multiple links to deliver data to users with the possibility of recoding at intermediate nodes. This phenomenon will reduce information congestion at some nodes or links, which will improve the network information flow such as to increase network throughput and robustness. This book is intended to provide the current R
Download or read book Design of Network Coding Schemes in Wireless Networks written by Zihuai Lin and published by CRC Press. This book was released on 2022-06-23 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a consolidated view of the various network coding techniques to be implemented at the design of the wireless networks for improving its overall performance. It covers multiple sources communicating with multiple destinations via a common relay followed by network coded modulation schemes for multiple access relay channels. Performance of the distributed systems based on distributed convolutional codes with network coded modulation is covered including a two-way relay channel (TWRC). Two MIF protocols are proposed including derivation of signal-to-noise ratio (SNR) and development of threshold of the channel conditions of both. Features: Systematically investigates coding and modulation for wireless relay networks. Discusses how to apply lattice codes in implementing lossless communications and lossy source coding over a network. Focusses on theoretical approach for performance optimization. Includes various network coding strategies for different networks. Reviews relevant existing and ongoing research in optimization along with practical code design. This book aims at Researchers, Professionals and Graduate students in Networking, Communications, Information, Coding Theory, Theoretical Computer Science, Performance Analysis and Resource Optimization, Applied Discrete Mathematics, and Applied Probability.
Download or read book Physical Layer Network Coding for the Multi way Relay Channel written by Behnam Hashemitabar and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless networks have received considerable attention recently due to the high user demand for wireless services and the emergence of new applications. This thesis focuses on the problem of information dissemination in a class of wireless networks known as the multi-way relay channel. Physical layer network coding is considered to increase the throughput in these networks. First, an algorithm is proposed that increases the full data exchange throughput by 33% compared to traditional routing. This gain arises from providing common knowledge to users and exploiting this knowledge to restrain some users from transmitting. Second, for complex field network coding, a transmission scheme is designed that ensures the receipt of a QAM constellation at the relay. This requires precoding the user symbols to make all possible combinations distinguishable at the relay. Using this approach, the throughput of data exchange is 1/2 symbol per user per channel use. The error performance of both schemes is derived analytically for AWGN channels.
Download or read book Soft Prioritized Network Coding in Multiple Access Relay Networks written by Navneet Malani and published by . This book was released on 2011 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Relay Selection in Two hop Wireless Communications written by MinChul Ju and published by . This book was released on 2010 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: Relay communication has been shown to be effective to extend service coverage and mitigate channel impairments. This thesis focuses on relay selection (RS) of both unidirectional and bidirectional relay networks employing the amplify-and-forward (AF) and decode-and-forward (DF) protocols. This thesis presents four works on RS in two-hop relay networks. In the first work, we study opportunistic relaying (OR) and selection cooperation (SC) in DF-based unidirectional multi-antennas relay networks. We first propose two joint relay-and-antenna selection schemes which combine OR and SC, respectively, with transmit antenna selection. For each joint selection scheme, a single best transmit antenna at the source, a single best relay, and a single best transmit antenna at this selected relay are jointly determined. Then we derive the outage probabilities, and show that the two schemes achieve the same outage performance. In the second work, we study RS with the physical-layer network coding (PNC) in DF-based bidirectional relay networks. By modifying the well-known SC and OR, we first propose two RS schemes for the PNC network: SC-PNC and OR-PNC. Then we derive the outage probability and diversity order of the SC-PNC. Finally, we show that the OR-PNC achieves the same outage performance as the SC-PNC. In the third work, we study RS with the analog network coding (ANC) and time division broadcast (TDBC), in AF-based bidirectional relay networks. We first consider RS schemes for the ANC and TDBC protocols based on a max-min criterion. Then we derive outage probabilities for the ANC and TDBC protocols. In the fourth work, we study joint relay-and-source selection in an AF-based bidirectional relay network. Since RS and opportunistic source selection (OSS) could individually improve performance of relay networks, we propose a joint RS-OSS protocol. In this network, a best source is selected to transmit data to the other source with the help of a selected best relay. Then, we derive the outage probability and average bit-error rate. The considered RS schemes and obtained outage probability expressions will help the design of two-hop wireless communications in determining the system parameters such as relay location and the transmission power at each terminal.
Download or read book Performance Analysis of Amplify and Forward Wireless Relay Networks written by Muhammad Khalil and published by . This book was released on 2017 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless relay technology plays an important role in the next-generation mobile and wireless networks. It has been proposed as a cost effective solution to addressing a growing demand for high data rates and low power consumption. In the relay communication model, a source communicates to a destination through a wireless node(s) called a relay. There are two main relaying techniques: Decode-and-Forward (DF) and Amplify-and-Forward (AF). AF is the focus of this thesis. The AF relay networks provide considerable performance improvement in link reliability, Spectral Efficiency (SE), Energy Efficiency (EE) and Bit Error Rate (BER) performance. They also offer a low-complexity solution for practical relay networks that have critical energy constraints, as they enable the received signal to be amplified without the decoding process at the relays. This thesis proposes new methods of reducing the energy consumption and evaluating the error performance of AF relay networks, when the relay is either one-way (unidirectional) or two-way (bidirectional). The analysis is commenced by formulating the actual Signals-to-Noise Ratio (SNR) level, which corresponds to a low SNR level, in order to calculate the Exact Bit Error Rate (EBER) performance. Then, the approximated SNR, which refers to a high SNR level, is expressed and adopted to evaluate the Asymptotic Bit Error Rate (ABER). Another SNR level is presented in this work and defined as an optimal SNR level, which is obtained by optimal balancing of the SE and EE. The optimal SNR level allows evaluation of the ABER and the EBER of AF relay networks under optimal SNR conditions. Accordingly, a unifying BER evaluation at low, high, and optimal levels of AF relay networks is provided in this study. This thesis focuses on a high SNR level to derive an effective method for evaluating the ABER and EBER, whether in optimal or sub-optimal AF relay networks. The effectiveness of such a BER evaluation method is demonstrated by enhancing the ABER of AF relay networks at all SNR levels (i.e., low, high, optimal SNR levels). This is shown when disparity between the ABER and the EBER at a low SNR level is reduced, and this helps to calculate the accurate BER of AF relay networks under any SNR levels using either the ABER or EBER. The proposed methods are examined under different channels environments, as in practice the channel of each hop of an AF relay network can be located in a different environment. When both hops are located in the same environment, the fading channels of the hops are equal, while for different environments, the fading channels of the hops are different. Furthermore, relay location is also investigated for the aforementioned ABER and EBER, and a new method for determining the relationship between the EE and EBER with relay location is derived.
