Efficient Transmission Techniques in Cooperative Networks: Forwarding Strategies and Distributed Coding Schemes PDF Download

Author: Xuanxuan Lu
Publisher:
ISBN: 9781369637298
Category :
Languages : en
Pages : 186

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Book Description
To circumvent the catastrophic error propagation in digital distributed coding scheme, a distributed soft coding scheme is proposed for the parallel relay networks. The key idea is the exploitation of a rate-1 soft convolutional encoder at each of the parallel relays, to collaboratively form a simple but powerful distributed analog coding scheme. Because of the linearity of the truncated LLR information, a nearly optimal ML decoder is derived for the distributed coding scheme.

Author: Atoosa Hatefi
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
With the rapid growth of wireless technologies, devices and mobile applications, the quest of high throughput and ubiquitous connectivity in wireless communications increases rapidly as well. Relaying is undoubtedly a key concept to provide coverage extension and capacity increase in wireless networks. Network coding, which allows the intermediate nodes to share their computation capabilities in addition to their resource and their power, has grabbed a significant research attention since its inception in information theory. It has become an attractive candidate to bring promising performance improvement, especially in terms of throughput, in relay-based cellular networks. Substantial research efforts are currently focused on theoretical analysis, implementation and evaluation of network coding from a physical layer perspective. The question is, what is the most efficient and practical way to use network coding in wireless relay-based networks, and whether it is beneficial to exploit the broadcast and multiple-access properties of the wireless medium to perform network coding. It is in such a context, that this thesis proceeds. In the first part of the thesis, the problem of Joint Network-Channel Coding (JNCC) for a Multiple Access Relay Channel (MARC) is investigated in the presence of multiple access interferences and for both of the relay operating modes, namely, half-duplex and full-duplex. To this end, three new classes of MARC, referred to as Half-Duplex Semi-Orthogonal MARC (HD-SOMARC), Half-Duplex Non-Orthogonal MARC (HD-NOMARC), and Full-Duplex Non-Orthogonal MARC (FD-NOMARC) have been introduced and studied. The relaying function in all of the classes is based on a Selective Decode-and-Forward (SDF) strategy, which is individually implemented for each source, i.e, the relay forwards only a deterministic function of the error-free decoded messages. For each class, an information-theoretic analysis is conducted, and practical coding and decoding techniques are proposed. The proposed coding schemes, perform very close to the outage limit for both cases of HD-SOMARC and HD-NOMARC. Besides, in the case of HD-NOMARC, the optimal allocation of the transmission time to the relay is considered. It is also verified that exploiting multiple access interferences, either partially or totally, results in considerable gains for MARC compared to the existing interference-avoiding structures, even in the case of single receive antenna. In the second part of the thesis, the network model is extended by considering multiple relays which help multiple sources to communicate with a destination. A new class of Multiple Access Multiple Relay Channel (MAMRC), referred to as Half-Duplex Semi-Orthogonal MAMRC (HD-SOMAMRC) is then proposed and analyzed from both information theoretic and code design perspective. New practical JNCC schemes are proposed, in which binary channel coding and non binary network coding are combined, and they are shown to perform very close to the outage limit. Moreover, the optimal allocation of the transmission time to the sources and relays is considered. Finally, in the third part of the thesis, different ways of implementing cooperation, including practical relaying protocols are investigated for the half-duplex MARC with semi-orthogonal transmission protocol and in the case of JNCC. The hard SDF approach is compared with two Soft Decode and Forward (SoDF) relaying functions: one based on log a posterior probability ratios (LAPPRs) and the other based on Mean Square Error (MSE) estimate. It is then shown that SDF works well in most of the configurations and just in some extreme cases, soft relaying functions (based on LAPPR or MSE estimate) can slightly outperform the hard selective one.

Author: Gbenga Adetokunbo Owojaiye
Publisher:
ISBN:
Category :
Languages : en
Pages :

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In this thesis, space-time block codes originally developed for multiple antenna systems are extended to cooperative multi-hop networks. The designs are applicable to any wireless network setting especially cellular, adhoc and sensor networks where space limitations preclude the use of multiple antennas. The thesis first investigates the design of distributed orthogonal and quasi-orthogonal space time block codes in cooperative networks with single and multiple antennas at the destination. Numerical and simulation results show that by employing multiple receive antennas the diversity performance of the network is further improved at the expense of slight modification of the detection scheme. The thesis then focuses on designing distributed space time block codes for cooperative networks in which the source node participates in cooperation. Based on this, a source-assisting strategy is proposed for distributed orthogonal and quasi-orthogonal space time block codes. Numerical and simulation results show that the source-assisting strategy exhibits improved diversity performance compared to the conventional distributed orthogonal and quasi-orthogonal designs. Motivated by the problem of channel state information acquisition in practical wireless network environments, the design of differential distributed space time block codes is investigated. Specifically, a co-efficient vector-based differential encoding and decoding scheme is proposed for cooperative networks. The thesis then explores the concatenation of differential strategies with several distributed space time block coding schemes namely; the Alamouti code, square-real orthogonal codes, complex-orthogonal codes, and quasiorthogonal codes, using cooperative networks with different number of relay nodes. In order to cater for high data rate transmission in non-coherent cooperative networks, differential distributed quasi-orthogonal space-time block codes which are capable of achieving full code-rate and full diversity are proposed. Simulation results demonstrate that the differential distributed quasi-orthogonal space-time block codes outperform existing distributed space time block coding schemes in terms of code rate and bit-error-rate performance. A multidifferential distributed quasi-orthogonal space-time block coding scheme is also proposed to exploit the additional diversity path provided by the source-destination link. A major challenge is how to construct full rate codes for non-coherent cooperative broadband networks with more than two relay nodes while exploiting the achievable spatial and frequency diversity. In this thesis, full rate quasi-orthogonal codes are designed for noncoherent cooperative broadband networks where channel state information is unavailable. From this, a generalized differential distributed quasi-orthogonal space-frequency coding scheme is proposed for cooperative broadband networks. The proposed scheme is able to achieve full rate and full spatial and frequency diversity in cooperative networks with any number of relays. Through pairwise error probability analysis we show that the diversity gain of the proposed scheme can be improved by appropriate code construction and sub-carrier allocation. Based on this, sufficient conditions are derived for the proposed code structure at the source node and relay nodes to achieve full spatial and frequency diversity. In order to exploit the additional diversity paths provided by the source-destination link, a novel multidifferential distributed quasi-orthogonal space-frequency coding scheme is proposed. The overall objective of the new scheme is to improve the quality of the detected signal at the destination with negligible increase in the computational complexity of the detector. Finally, a differential distributed quasi-orthogonal space-time-frequency coding scheme is proposed to cater for high data rate transmission and improve the performance of noncoherent cooperative broadband networks operating in highly mobile environments. The approach is to integrate the concept of distributed space-time-frequency coding with differential modulation, and employ rotated constellation quasi-orthogonal codes. From this, we design a scheme which is able to address the problem of performance degradation in highly selective fading environments while guaranteeing non-coherent signal recovery and full code rate in cooperative broadband networks. The coding scheme employed in this thesis relaxes the assumption of constant channel variation in the temporal and frequency dimensions over long symbol periods, thus performance degradation is reduced in frequencyselective and time-selective fading environments. Simulation results illustrate the performance of the proposed differential distributed quasi-orthogonal space-time-frequency coding scheme under different channel conditions.

Author: Uysal, Murat
Publisher: IGI Global
ISBN: 1605666661
Category : Computers
Languages : en
Pages : 632

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Book Description
Offers practitioners, researchers, and academicians with fundamental principles of cooperative communication. This book provides readers diverse findings and exposes underlying issues in the analysis, design, and optimization of wireless systems.

Author: Azzam Al-Nahari
Publisher: LAP Lambert Academic Publishing
ISBN: 9783659176753
Category :
Languages : en
Pages : 184

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Book Description
Cooperative communications is a new paradigm in the wireless communications area that allows geographically distributed nodes, terminals or sensors in a wireless network to share resources or to cooperate by means of distributed processing. The main goal of cooperative communications is to attain space diversity for suppressing the effects of small or large scale fading channels. In this book, we consider the design of distributed coding schemes and protocols for wireless relay networks in which users cooperate to send their data to the destination, which results in increasing the system reliability via achieving the cooperative diversity.

Author: Mohammed Taha El Astal
Publisher: LAP Lambert Academic Publishing
ISBN: 9783844392685
Category :
Languages : en
Pages : 100

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Book Description
Space- Time Block Coding (STBC) are used to improve the transmission reliably and spectral efficiency of MIMO systems. The cooperative communication techniques can avoid the difficulties of implementing actual antennas array by converting the single-input single-output (SISO) system into a virtual multiple-input multiple-output (MIMO) system. When STBC applied to cooperative diversity the system termed as Distributed Space Time Block Code (D-STBC). Most of the existing research assumes perfect synchronization among cooperative users in D-STBC. Unfortunately, perfect synchronization is almost impossible to be achieved. Therefore, most of the designed space-time codes are no longer valid. There are different research efforts to overcome this problem; most of which has high decoding complexity. In this research, two low decoding complexity schemes for imperfect synchronized D-STBC have been proposed. The first scheme is based on the principle of parallel interference cancellation (PIC), whereas the other is based on successive interference cancellation (SIC). These approaches have been proved to be a very effective in suppressing the impact of imperfect synchronization.

Author: Kien Trung Nguyen
Publisher:
ISBN:
Category :
Languages : en
Pages : 211

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Book Description
The classical store-and-forward routing has and will continue to be the most important routing architecture in many modern packet-switched communication networks. In a packet-switched network, data is sent in the form of discrete packets that traverse hop-by-hop from a source to a destination. At each intermediate hop, the router stores and examines the packets it receives then forwards them to the next hop until they reach the correct destinations according to some pre-defined routing algorithms. Importantly, the intermediate routers do not modify but simply store and forward the contents of the packets. In contrast, a new generalized approach to routing called Network Coding (NC) allows the intermediate routers to modify and combine packets from different sources and destinations in such a way that increases the overall throughput. The core idea of NC allowing the intermediate nodes in a network to perform data processing has a wide range of applications well beyond its initial application to routing, impacting different disciplines from distributed data storage and security to energy efficient sensor networks and Internet media streaming. To that end, this dissertation aims to develop the theories and applications of NC via four main thrusts: 1) Energy efficient NC techniques for sensor networks, 2) Novel NC techniques and protocols for Internet video streaming, 3) Stochastic data replenishment for large scale NC-based distributed storage systems, 4) Real-world implementation of NC-based distributed video streaming system. In thrust one, we describe a novel cross-sensor coding technique that combines network topology and coding techniques to maximize the life-time of a sensor network, by addressing the uneven energy consumption problem in data gathering sensor networks where the nodes closer to the sink tend to consume more energy than those of the farther nodes. Our approach is based on the following observation from the sensor networks using On-Off Keying and digital transmission: transmitting bit "1" consumes much more energy than bit "0". Our proposed coding technique exploits this difference to reduce the communication energy by limiting the number of bits "1" in the output codeword (low-weight codeword) and to use NC-based cross-sensor coding technique to equalize the communication energy among the nodes. This cross-sensor coding scheme can significantly extend the network lifetime as compared with traditional (binary) coding by solving the energy-consumption unfairness problem. The theoretical and experimental results confirm that transmission energy can be reduced substantially (e.g., a factor of 15) and the unequal energy consumption among nodes can be practically eliminated. In thrust two, we describe a rate distortion aware hierarchical NC technique and transport protocol for Internet video streaming. We begin by proposing a NC-based multi-sender streaming framework that reduces the overall storage, eliminates the complexity of sender synchronization, and enables TCP streaming. Furthermore, we propose a Hierarchical Network Coding (HNC) technique that facilitates scalable video streaming to combat bandwidth fluctuation on the Internet. This HNC technique enables receiver to recover the important data gracefully in the presence of limited bandwidth which causes an increase in decoding delay. Simulations demonstrate that under certain scenarios, our proposed NC techniques can result in bandwidth saving up to 60% over the traditional schemes. In thrust three, we present a theory of NC-based data replenishment to automate the process of data maintenance for large scale distributed storage systems. The data replenishment mechanism is the core of these systems that promises to reduce the coordination complexity and increases performance scalability. The data replenishment automates the process of maintaining a sufficient level of data redundancy to ensure the availability of data in presence of peer departures and failures. The dynamics of peers entering and leaving the network is modeled as a stochastic process. We propose a novel analytical time-backward technique to bound the expected time, the longer the better, for a piece of data to remain in P2P systems. Both theoretical and simulation results are in agreement, indicating that our proposed data replenishment via random linear network coding (RLNC) outperforms other popular strategies that employ repetition and channel coding techniques. Specifically, we show that the expected time for a piece of data to remain in a P2P system is exponential in the number of peers used to store the data for the RLNC-based strategy, while they are quadratic for other strategies. Furthermore, the time-backward technique can be applied to problems in other disciplines such as gene population modeling in theoretical biology. Finally in thrust four, we present the architecture, design, and experimental results of an actual NC-based distributed video streaming system. We first implement random linear network coding (RLNC) library and show the feasibility of using RLNC in P2P video streaming applications. Then we design, implement and analyze RESnc - a resilient P2P video storage and streaming over the Internet using network coding. RESnc increases the streaming throughput and data resiliency against peer departures and failures using peer diversity. These improvements are based on three architectural elements: 1) The RLNC scheme that breaks a video stream into multiple smaller pieces, codes, and disperses them throughout peers in the network, in such a way to maximize the probability of recovering the original video under peer departures and failures; 2) The scalable mechanism for automating the data replenishment process using RLNC to maintain a sufficient level of redundancy for video stored in the system; 3) The path-diversity streaming protocol for a client to simultaneously stream a video from multiple peers with minimal coordination. Experimental results demonstrated that our system adapts well with bandwidth fluctuation, provides significant playback quality improvement and bandwidth saving.

Author: Renqiu Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 284

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Author: Yanru Tang
Publisher:
ISBN: 9781680834697
Category : Coding theory
Languages : en
Pages : 153

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Book Description
With the fast expansion of communication networks and the increasing dynamic of wireless communication activities, a significant proportion of messages in wireless networks are being transmitted using distributed protocols that feature opportunistic channel access without full user coordination. This challenges the basic assumption of long message transmissions among coordinated users in classical channel coding theory. In this monograph, we introduce channel coding theorems for the distributed communication model where users choose their channel codes individually. We show that, although reliable message recovery is not always guaranteed in distributed communication systems, the notion of fundamental limit still exists, and can indeed be viewed as an extension to its classical correspondence. Due to historical priority of developing wireline networks, network architectures tend to achieve system modularity by compromising communication and energy efficiency. Such a choice is reasonable for wireline systems but can be disastrous for wireless radio networks. Therefore, to reduce efficiency loss, large scale communication networks often adopt wireless communication only at the last hop. Because of such a special structure, architectural inefficiency in wireless part of the network can be mitigated by enhancing the interface between the physical and the data link layers. The enhanced interface, to be proposed, provides each link layer user with multiple transmission options, and supports efficient distributed networking by enabling advanced communication adaptation at the data link layer. In this monograph, we focus on the introduction of distributed channel coding theory, which serves as the physical layer foundation for the enhanced physical-link layer interface. Nevertheless, early research results at the data link layer for the enhanced interface are also presented and discussed.

Author: Xingang Liu
Publisher: Springer
ISBN: 3030061612
Category : Computers
Languages : en
Pages : 743

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Book Description
The book constitutes the refereed proceedings of the 13th EAI International Conference on Communications and Networking, held in October 2018 in Chengdu, China. The 71 papers presented were carefully selected from 114 submissions. The papers are organized in topical sections on wireless communications and networking, next generation WLAN, big data networks, cloud communications and networking, ad hoc and sensor networks, satellite and space communications and networking, optical communications and networking, information and coding theory, multimedia communications and smart networking, green communications and computing, signal processing for communications, network and information security, machine-to-machine and IoT, communication QoS, reliability and modeling, cognitive radio and networks, smart internet of things modeling, pattern recognition and image signal processing, digital audio and video signal processing, antenna and microwave communications, radar imaging and target recognition, and video coding and image signal processing.