Download or read book Data Rate Optimization for Two way Relay Channel with Physical layer Network Coding written by Shanshan Huang and published by . This book was released on 2013 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Analysis and Design of Communication Techniques in Spectrally Efficient Wireless Relaying Systems written by Jian Zhao and published by Logos Verlag Berlin GmbH. This book was released on 2010 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation studies the communication technologies in relaying systems with multiple antennas, especially in the multiple-input multiple-output (MIMO) two-way relaying systems. Both information-theoretic aspects and practical communication strategies are considered and analyzed. For the information-theoretic analysis, an analytical framework for the coverage of MIMO relaying systems based on an outage capacity criterion is proposed. For MIMO two-way relaying systems, different data combining schemes at the relay are compared based on their achievable rates. In addition, optimal time-division (TD) strategies for MIMO two-way decode-and-forward (DF) relaying systems are proposed and analyzed. When the optimal TD strategies are applied, the increase of the achievable rate regions in the system is significant compared to those using the equal TD strategy. For the practical transmission schemes, we propose the self-interference (SI) aided channel estimation and data detection schemes for the broadcast phase of two-way DF relaying systems. Such schemes exploit the SI in two-way DF relaying systems when the superposition coding (SPC) scheme is applied. When the network coding scheme is applied in two-way DF relaying systems, we propose an asymmetric data rate transmission scheme that utilizes the known data bits at the receivers. Such a scheme exploits the a priori known bits at the weak link receiver in the broadcast phase of two-way relaying systems.

Download or read book Coding Schemes for Physical Layer Network Coding Over a Two Way Relay Channel written by Brett Michael Hern and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We consider a two-way relay channel in which two transmitters want to exchange information through a central relay. The relay observes a superposition of the trans- mitted signals from which a function of the transmitted messages is computed for broadcast. We consider the design of codebooks which permit the recovery of a function at the relay and derive information-theoretic bounds on the rates for reliable decoding at the relay. In the spirit of compute-and-forward, we present a multilevel coding scheme that permits reliable computation (or, decoding) of a class of functions at the relay. The function to be decoded is chosen at the relay depending on the channel realization. We define such a class of reliably computable functions for the proposed coding scheme and derive rates that are universally achievable over a set of channel gains when this class of functions is used at the relay. We develop our framework with general modulation formats in mind, but numerical results are presented for the case where each node transmits using 4-ary and 8-ary modulation schemes. Numerical results demonstrate that the flexibility afforded by our proposed scheme permits substantially higher rates than those achievable by always using a fixed function or considering only linear functions over higher order fields. Our numerical results indicate that it is favorable to allow the relay to attempt both compute-and-forward and decode-and-forward decoding. Indeed, either method considered separately is suboptimal for computation over general channels. However, we obtain a converse result when the transmitters are restricted to using identical binary linear codebooks generated uniformly at random. We show that it is impossible for this code ensemble to achieve any rate higher than the maximum of the rates achieved using compute-and-forward and decode-and-forward decoding. Finally, we turn our attention to the design of low density parity check (LDPC) ensembles which can practically achieve these information rates with joint-compute- and-forward message passing decoding. To this end, we construct a class of two-way erasure multiple access channels for which we can exactly characterize the performance of joint-compute-and-forward message passing decoding. We derive the processing rules and a density evolution like analysis for several classes of LDPC ensembles. Utilizing the universally optimal performance of spatially coupled LDPC ensembles with message passing decoding, we show that a single encoder and de- coder with puncturing can achieve the optimal rate region for a range of channel parameters. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151149

Download or read book Cross layer Design for Multi hop Two way Relay Network written by Haoyuan Zhang and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Physical layer network coding (PNC) was proposed under the two-way relay hannel (TWRC) scenario, where two sources exchange information aided by a relay. PNC allows the two sources to transmit to the relay simultaneously, where superimposed signals at the relay can be mapped to network-coded symbols and then be broadcast to both sources instead of being treated as interference. Concurrent transmissions using PNC achieve a higher spectrum efficiency compared to time division and network coding solutions. Existing research mainly focused on the symmetric PNC designs, where the same channel coding and modulation configurations are applied by both sources. When the channel conditions of the two source-relay links are asymmetric or unequal amount of data are exchanged, heterogeneous modulation PNC designs are necessary. In additional, the design and optimization of multi-hop PNC, where multiple relays forming a multi-hop path between the two sources, remains an open issue. The above issues motivate the study of this dissertation.This dissertation investigates the design of heterogeneous modulation physicallayer network coding (HePNC), the integration of channel error control coding into HePNC, the combination of HePNC with hierarchical modulation, and the design and generalization of multi-hop PNC. The contributions of this dissertation are four-fold.First, under the asymmetric TWRC scenario, where the channel conditions ofthe two source-relay links are asymmetric, we designed a HePNC protocol, including the optimization of the adaptive mapping functions and the bit-symbol labeling, to minimize the end-to-end BER. In addition, we developed an analytical framework to derive the BER of HePNC. HePNC can substantially enhance the throughput compared to the existing symmetric PNC under the asymmetric TWRC scenario.Second, we investigated channel coded HePNC and integrated the channel errorcontrol coding into HePNC in a link-to-link coding, where the relay tries to decode the superimposed codewords in the multi-access stage. A full-state sum-product decoding algorithm is proposed at the relay based on the repeat-accumulate codes to guarantee reliable end-to-end communication.Third, we proposed hierarchical modulation PNC (H-PNC) under asymmetric TWRC, where additional data exchange between the relay and the source with the relatively better channel condition is achieved in addition to that between the two end sources, benefiting from superimposing the additional data flow on the PNC transmission. When the relay also has the data exchange requirement with the source with a better source-relay channel, H-PNC outperforms HePNC and PNC in terms of the system sum throughput.Fourth, we designed and generalized multi-hop PNC, where multiple relays located in a linear topology are scheduled to support the data exchange between two end sources. The impact of error propagation and mutual interference among the nodes are addressed and optimized. The proposed designs outperform the existing ones in terms of end-to-end BER and end-to-end throughout.

Download or read book Nature Inspired Algorithms and Applied Optimization written by Xin-She Yang and published by Springer. This book was released on 2017-10-08 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews the state-of-the-art developments in nature-inspired algorithms and their applications in various disciplines, ranging from feature selection and engineering design optimization to scheduling and vehicle routing. It introduces each algorithm and its implementation with case studies as well as extensive literature reviews, and also includes self-contained chapters featuring theoretical analyses, such as convergence analysis and no-free-lunch theorems so as to provide insights into the current nature-inspired optimization algorithms. Topics include ant colony optimization, the bat algorithm, B-spline curve fitting, cuckoo search, feature selection, economic load dispatch, the firefly algorithm, the flower pollination algorithm, knapsack problem, octonian and quaternion representations, particle swarm optimization, scheduling, wireless networks, vehicle routing with time windows, and maximally different alternatives. This timely book serves as a practical guide and reference resource for students, researchers and professionals.

Download or read book Computational Data and Social Networks written by Minh Hoàng Hà and published by Springer Nature. This book was released on with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 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 Channel Coded Physical layer Network Coding in Wireless Relay Networks written by Xiaokang Wang and published by . This book was released on 2018 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Coding for Relay Networks with Parallel Gaussian Channels written by Yu-Chih Huang and published by . This book was released on 2013 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: A wireless relay network consists of multiple source nodes, multiple destination nodes, and possibly many relay nodes in between to facilitate its transmission. It is clear that the performance of such networks highly depends on information forwarding strategies adopted at the relay nodes. This dissertation studies a particular information forwarding strategy called compute-and-forward. Compute-and-forward is a novel paradigm that tries to incorporate the idea of network coding within the physical layer and hence is often referred to as physical layer network coding. The main idea is to exploit the superposition nature of the wireless medium to directly compute or decode functions of transmitted signals at intermediate relays in a network. Thus, the coding performed at the physical layer serves the purpose of error correction as well as permits recovery of functions of transmitted signals. For the bidirectional relaying problem with Gaussian channels, it has been shown by Wilson et al. and Nam et al. that the compute-and-forward paradigm is asymptotically optimal and achieves the capacity region to within 1 bit; however, similar results beyond the memoryless case are still lacking. This is mainly because channels with memory would destroy the lattice structure that is most crucial for the compute-and-forward paradigm. Hence, how to extend compute-and-forward to such channels has been a challenging issue. This motivates this study of the extension of compute-and-forward to channels with memory, such as inter-symbol interference. The bidirectional relaying problem with parallel Gaussian channels is also studied, which is a relevant model for the Gaussian bidirectional channel with inter-symbol interference and that with multiple-input multiple-output channels. Motivated by the recent success of linear finite-field deterministic model, we first investigate the corresponding deterministic parallel bidirectional relay channel and fully characterize its capacity region. Two compute-and-forward schemes are then proposed for the Gaussian model and the capacity region is approximately characterized to within a constant gap. The design of coding schemes for the compute-and-forward paradigm with low decoding complexity is then considered. Based on the separation-based framework proposed previously by Tunali et al., this study proposes a family of constellations that are suitable for the compute-and-forward paradigm. Moreover, by using Chinese remainder theorem, it is shown that the proposed constellations are isomorphic to product fields and therefore can be put into a multilevel coding framework. This study then proposes multilevel coding for the proposed constellations and uses multistage decoding to further reduce decoding complexity. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149620

Download or read book Timing Synchronization at the Relay Node in Physical Layer Network Coding written by Ashish Basireddy and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent times, there has been an increased focus on the problem of information exchange between two nodes using a relay node. The introduction of physical layer network coding has improved the throughput efficiency of such an exchange. In practice, the reliability of information exchange using this scheme is reduced due to synchronization issues at the relay node. In this thesis, we deal with timing synchronization of the signals received at the relay node. The timing offsets of the signals received at the relay node are computed based on the propagation delays in the transmitted signals. However, due to the random attenuation of signals in a fading channel, the near far problem is inherent in this situation. Hence, we aim to design near far resistant delay estimators for this system. We put forth four algorithms in this regard. In all the algorithms, propagation delay of each signal is estimated using a known preamble sent by the respective node at the beginning of the data packet. In the first algorithm, we carefully construct the preamble of each data packet and apply the MUSIC algorithm to overcome the near far problem. The eigenstructure of the correlation matrix is exploited to estimate propagation delay. Secondly, the idea of interference cancellation is implemented to remove the near far problem and delay is estimated using a correlator. Thirdly, a modified decorrelating technique is presented to negate the near far problem. Using this technique we aim to obtain an estimate of the weak user's delay that is more robust to errors in the strong user's delay estimate. In the last algorithm, pilot signals with desired autocorrelation and cross correlation functions are designed and a sliding correlator is used to estimate delay. Even though this approach is not near far resistant, performance results demonstrate that for the length's of preamble considered, this algorithm performs similar to the other algorithms.

Download or read book Interference Alignment written by Syed A. Jafar and published by Now Publishers Inc. This book was released on 2011 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interference Alignment: A New Look at Signal Dimensions in a Communication Network provides both a tutorial and a survey of the state-of-art on the topic.

Download or read book Developments in Wireless Network Prototyping Design and Deployment Future Generations written by Matin, Mohammad A. and published by IGI Global. This book was released on 2012-06-30 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This book highlights the current design issues in wireless networks, informing scholars and practitioners about advanced prototyping innovations in this field"--

Download or read book IT Policy and Ethics Concepts Methodologies Tools and Applications written by Management Association, Information Resources and published by IGI Global. This book was released on 2013-02-28 with total page 1940 pages. Available in PDF, EPUB and Kindle. Book excerpt: IT policies are set in place to streamline the preparation and development of information communication technologies in a particular setting. IT Policy and Ethics: Concepts, Methodologies, Tools, and Applications is a comprehensive collection of research on the features of modern organizations in order to advance the understanding of IT standards. This is an essential reference source for researchers, scholars, policymakers, and IT managers as well as organizations interested in carrying out research in IT policies.

Download or read book Design and Performance Optimization of Wireless Network Coding for Delay Sensitive Applications written by Mohammad Esmaeilzadeh Fereydani and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade, network coding (NC) has emerged as a new paradigm for data communications and has attracted much popularity and research interest in information and coding theory, networking, wireless communications and data storage. Random linear NC (RLNC) is a subclass of NC that has shown to be suitable for a wide range of applications thanks to its desirable properties, namely throughput-optimality, simple encoder design and efficient operation with minimum feedback requirements. However, for delay-sensitive applications, the mentioned advantages come with two main issues that may restrict RLNC usage in practice. First is the trade-off between the delay and throughput performances of RLNC, which can adversely affect the throughput-optimality of RLNC and hence the overall performance of RLNC. Second is the usage of feedback, where even if feedback is kept at minimum it can still incur large amount of delay and thus degrade the RLNC performance, if not optimized properly. In this thesis, we aim to investigate these issues under two broad headings: RLNC for applications over time division duplexing (TDD) channels and RLNC for layered video streaming. For the first class of problems, we start with the reliable broadcast communication over TDD wireless channels with memory, in the presence of large latency. Considering TDD channels with large latency, excessive use of feedback could be costly. Therefore, joint optimization of feedback rate and RLNC parameters has been studied previously for memoryless channels to minimize the average transmission time for such settings. Here, we extend the methodology to the case of channels with memory by benefiting from a Gilbert-Elliot channel model. It is demonstrated that significant improvement in the performance could be achieved compared to the scheme which is oblivious to the temporal correlations in the erasure channels. Then, keeping our focus on network coded TDD broadcast systems with large latency, we consider delay sensitive applications and study the issue of throughput and packet drop rate (PDR) optimization as two performance metrics when the transmission time is considered fixed. We propose a systematic framework to investigate the advantage of using feedback by comparing feedback-free and feedback schemes. Furthermore, the complicated interplay of the mean throughputs and PDRs of users with different packet erasure conditions is discussed. Then, to better analyze the throughput performance of the proposed feedback-free scheme, we formulate the probability and cumulative density functions of users' throughputs and utilize them to investigate the problem of guaranteeing the quality of service. Finally, it is shown that the optimized feedback-free RLNC broadcast scheme works close enough to an idealistic RLNC scheme, where an omniscient sender is assumed to know the reception status of all users immediately after each transmission. For the second class of problems, we consider transmitting layered video streams over heterogeneous single-hop wireless networks using feedback-free RLNC. For the case of broadcasting single video stream, we combine RLNC with unequal error protection and our main purpose is twofold. First, to systematically investigate the benefits of the layered approach in servicing users with different reception capabilities. Second, to study the effect of not using feedback, by comparing feedback-free schemes with idealistic full-feedback schemes. To this end, we consider a content-independent performance metric and propose a general framework for calculation of this metric, which can highlight the effect of key parameters of the system, video and channel. We study the effect of number of layers and propose a scheme that selects the optimum number of layers adaptively to achieve the highest performance. Assessing the proposed schemes with real H.264 test streams, the trade-offs among the users' performances are discussed and the gain of adaptive selection of number of layers to improve the trade-offs is shown. Furthermore, it is observed that the performance gap between the proposed feedback-free scheme and the idealistic scheme is small and the adaptive selection of number of video layers further closes the gap. Finally, we extend the problem of layered video streaming to the case of transmitting multiple independent layered video streams and demonstrate the gain of coding across streams (i.e., inter-session RLNC) over coding only within streams (i.e., intra-session RLNC).