Resource Allocation For Layered Broadcast Over Relay Assisted Channels
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Resource Allocation For Layered Broadcast Over Relay Assisted Channels
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Author : Mohamed Adel Attia
language : en
Publisher:
Release Date : 2015
Resource Allocation For Layered Broadcast Over Relay Assisted Channels written by Mohamed Adel Attia and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Broadcast data systems categories.
Abstract: The topic of this thesis is on the application of "multilayer transmission" using the broadcast approach on a "relay-assisted" channel. Unlike single layer transmission, where all transmitted information bits have the same protection level by the channel coding scheme, multilayer transmission schemes combine successive refinement layered source coding with ordered protection levels of the source layers. Consequently, the receiver will be able to decode "some" information when the channel is faded and "all" information when the channel is good. The multilayer transmission schemes have gained a lot of interest in the information theory and the communication theory literature, where most researchers are interested in the "broadcast approach" since it is the optimal transmission strategy. In this thesis, we consider a fading relay channel where the source uses layered source coding with successive refinement. The source layers are transmitted using superposition coding at the source with optimal resource allocation. The destination applies successive interference cancellation after optimally combining the direct and relayed signals. The resource allocation for the layers is subject to optimization in order to maximize the expected user satisfaction that is usually defined by a differentiable concave increasing utility function of the total decoded rate at the destination. As special cases, we consider two utility functions; namely, the expected total decoded rate at the receiver and the expected rate distortion of a Gaussian source. We also assume that only the channel statistics are known at the receiver. The relay is half-duplex and applies different relaying strategies, and we have investigated the Amplify-and-Forward, and Decode-and-Forward strategies in particular. First, we consider the case of Decode-and-Forward relays where we consider two layers only with predetermined rates for simplicity, and we solve the problem of optimal power allocation among the two layers at the source and the relay using random search methods. After that, we solve the optimal power allocation problem for any number of layers with fixed rates over an Amplify-and-Forward relays. An approximation for the end-to-end channel quality is presented in terms of the statistics of the three links of the channel model. Furthermore, we obtain that for some conditions, it is optimal to send only one layer. Finally, we solve the joint optimal power and rate allocation problem for any number of layers over an Amplify-and-Forward relays. We also consider the theoretical case of infinite number of layers representing an upper bound for the performance. Moreover, we show that with a small number of layers, we can approach the performance upper bound. We provide many numerical examples for the three cases above to show the prospected gains of using the relays on the expected utility for different channel conditions.
Channel Estimation And Optimal Resource Allocation Of Relay Assisted Communication Systems
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Author : Yupeng Jia
language : en
Publisher:
Release Date : 2012
Channel Estimation And Optimal Resource Allocation Of Relay Assisted Communication Systems written by Yupeng Jia and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
"Exploding demand for various wireless services has fueled significant development of wireless communication systems and networks in the past few decades. Wireless service providers are continuously striving to improve the design of communication systems and to enable higher data rate and more reliable wireless transmission. A major challenge in designing these systems is the random nature of the wireless transmission media due to the fading process. A recent paradigm shift from the conventional point-to-point communications is relay assisted communications. Motivated by the great success of multiple-input multiple-output (MIMO) wireless communication systems, with multiple transmit and receive antennas, researchers have considered relay assisted communications. Relying on the broadcast nature of the wireless media, a relay assisted communication system emulates a virtual MIMO system and exploits the spatial diversity, also known as cooperative diversity. Cooperative diversity increases the transmission reliability and coverage, without expanding the expenditure of the scarce transmission resources (power and bandwidth). Recently, the research community has witnessed an increasing interest in studying relay assisted communication systems. These studies include proposing novel relaying schemes, exploring ways to maximize the cooperative gain, and investigating the fundamental performance limits of these systems. The bulk of the literature is based on the main assumption that the effect of fading channels (commonly referred to as channel state information) is perfectly known at the destination. In practical communication systems, however, the unknown fading channels are first estimated and the channel estimates are used for decoding the message transmitted by the source. In order to have a more realistic and accurate understanding of the benefits of relay assisted systems, one needs to study the effect of uncertainty, imposed by channel estimation error, on the fundamental performance limits. Such study can guide to a more efficient system design and provide optimal resource allocation between data and training (required for channel estimation). Two widely used relay assisted wireless communication systems are: 1) a one-way relay assisted system, in which there is a source, a relay and a destination, and the relay helps the source by forwarding the overheard message to the destination; 2) a two-way relay assisted system, in which two sources are interested in mutual communication, i.e., one source is the destination of the other source. In this system the relay helps both users by forwarding the overheard messages to the intended destinations. For each system, one can envision different system designs, depending on the specific relaying scheme and the specific signal processing algorithm adopted at the relay. The most commonly used relaying schemes are Amplify-and-Forward (AF) and Decodeand- Forward (DF), where in the former the relay amplifies and forwards the overheard messages, while in the latter, the relay decodes the overheard messages and then forwards them. In this thesis, we consider one-way and two-way AF relay assisted systems with a half-duplex relay. We study the impact of uncertainty, due to channel estimation errors, on the fundamental performance limits. In particular, we consider mean squared error (MSE) and the Bayesian Cramer -Rao lower bound (CRLB) for channel estimation as the estimation theoretic optimality criteria and channel mutual information lower bound and outage probability upper bound as the information theoretic optimality criteria. We explore how the negative effect of channel uncertainty can be mitigated, via optimal transmission resource allocation that maximizes or minimizes a specific optimality criteria. We also compare the bidirectional mutual information lower bounds of direct transmission without the relay, one-way AF relay and two-way AF relay systems. Furthermore, we examine the effect of joint optimization of the media access control and physical layers on the system throughput for one-way AF and DF relay assisted systems"--Abstract.
Cross Layer Resource Allocation For Multiple User Video Communication Systems
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Author : Dawei Wang
language : en
Publisher:
Release Date : 2013
Cross Layer Resource Allocation For Multiple User Video Communication Systems written by Dawei Wang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
In this dissertation, we investigate problems of resource allocation for uplink multiuser wireless communication channels. The users want to upload compressed video streams with different rate-distortion (RD) characteristics to a base station via a multi-carrier channel. The video is organized in groups of pictures (GOP), and the base station makes resource allocation decisions based jointly on the channel state information (CSI) and the RD information to minimize the average video distortion across all users. We first study the case where the channel is slowly varying. With the assumption of the channel staying constant over the duration of a GOP, we derive an optimal condition for minimizing the sum of distortions in a setting of continuous frequency channel response. Our result shows that for a specific band to be assigned to a particular user, the product of the slope of the RD curve of that user and a marginal rate increment corresponding to that band should be maximized. We then design an algorithm which iteratively calculates the status of the RD information and the CSI in a block fading setting. Compared to two baseline resource allocation algorithms that use only a single layer of information, the simulation results show that the cross layer scheme can consistently improve the performance of the system. We then focus on the case of a channel with arbitrary mobility. To better utilize the time varying channel, we design a pilot symbol assisted modulation (PSAM) system which periodically adapts the modulation format according to the instantaneous CSI. We show that the two baseline algorithms with single layer information behave quite differently as the Doppler spread changes, but the cross layer algorithm performs robustly across all different mobile speeds. We further characterize the capacity gain of using the cross layer scheme.
Resource Allocation In Relay Networks
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Author : Anahid Attarkashani
language : en
Publisher:
Release Date : 2018
Resource Allocation In Relay Networks written by Anahid Attarkashani and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
Demand for high data rates is increasing rapidly, due to the rapid rise of mobile data traffic volume. In order to meet the demands, the future generation of wireless communication systems has to support higher data rates and quality of service. The inherent unreliable and unpredictable nature of wireless medium provides a challenge for increasing the data rate. Cooperative communications, is a prominent technique to combat the detrimental fading effect in wireless communications. Adding relay nodes to the network, and creating s virtual multiple-input multiple-output (MIMO) antenna array is proven to be an efficient method to mitigate the multipath fading and expand the network coverage. Therefore, cooperative relaying is considered as a fundamental element in the Long Term Evolution (LTE)-Advanced standard. In this thesis, we address the problem of resource allocation in cooperative networks. We provide a detailed review on the resource allocation problem. We look at the joint subcarrier-relay assignment and power allocation. The objective of this optimization problem is to allocate the resources fairly, so even the cell-edge users with weakest communication links receive a fair share of resources. We propose a simple and practical algorithm to find the optimal solution. We assess the performance of the proposed algorithm by providing simulations. Furthermore, we investigate the optimality and complexity of the proposed algorithm. Due to the layered architecture of the wireless networks, to achieve the optimal performance it is necessary that the design of the algorithms be based on the underlying physical and link layers. For a cooperative network with correlated channels, we propose a cross-layer algorithm for relay selection, based on both the physical and link-layer characteristics, in order to maximize the linklayer throughput. The performance of the proposed algorithm is studied in different network models. Furthermore, we investigate the optimum number of relays required for cooperation in order to achieve maximum throughput. Buffering has proven to improve the performance of the cooperative network. In light of this, we study the performance of buffer-aided relay selection. In order to move one step closer to the practical applications, we consider a system with coded transmissions. We study three different coding schemes: convolutional code, Turbo code, and distributed Turbo code (DTC). For each scheme, the performance of the system is simulated and assessed analytically. We derive a closed form expression of the average throughput. Using the analysis results, we investigate the diversity gain of the system in asymptotic conditions. Further, we investigate the average transmission delay for different schemes.
Introduction To Cognitive Radio Networks And Applications
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Author : Geetam Tomar
language : en
Publisher: CRC Press
Release Date : 2016-10-03
Introduction To Cognitive Radio Networks And Applications written by Geetam Tomar and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-10-03 with Computers categories.
Cognitive radio is 5-G technology, comes under IEEE 802.22 WRAN (Wireless Regional Area Network) standards. It is currently experiencing rapid growth due to its potential to solve many of the problems affecting present-day wireless systems. The foremost objective of "Introduction to Cognitive Radio Networks and Applications" is to educate wireless communication generalists about cognitive radio communication networks. Written by international leading experts in the field, this book caters to the needs of researchers in the field who require a basis in the principles and the challenges of cognitive radio networks.
Channel Coding Theory Algorithms And Applications
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Author :
language : en
Publisher: Academic Press
Release Date : 2014-07-29
Channel Coding Theory Algorithms And Applications written by and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-07-29 with Technology & Engineering categories.
This book gives a review of the principles, methods and techniques of important and emerging research topics and technologies in Channel Coding, including theory, algorithms, and applications. Edited by leading people in the field who, through their reputation, have been able to commission experts to write on a particular topic. With this reference source you will: Quickly grasp a new area of research Understand the underlying principles of a topic and its applications Ascertain how a topic relates to other areas and learn of the research issues yet to be resolved Quick tutorial reviews of important and emerging topics of research in Channel Coding Presents core principles in Channel Coding theory and shows their applications Reference content on core principles, technologies, algorithms and applications Comprehensive references to journal articles and other literature on which to build further, more specific and detailed knowledge
Radio Resource Allocation Over Fading Channels Under Statistical Delay Constraints
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Author : Tho Le-Ngoc
language : en
Publisher:
Release Date : 2017
Radio Resource Allocation Over Fading Channels Under Statistical Delay Constraints written by Tho Le-Ngoc and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Computer Communication Networks categories.
Channel Aware Scheduling And Resource Allocation With Cross Layer Optimization In Wireless Networks
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Author : Sheu-Sheu Tan
language : en
Publisher:
Release Date : 2013
Channel Aware Scheduling And Resource Allocation With Cross Layer Optimization In Wireless Networks written by Sheu-Sheu Tan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
We develop channel aware scheduling and resource allocation schemes with cross-layer optimization for several problems in multiuser wireless networks. We consider problems of distributed opportunistic scheduling, where multiple users contend to access the same set of channels. Instead of scheduling users to the earliest available idle channels, we also take the instantaneous channel quality into consideration and schedule the users only when the channel quality is sufficiently high. This can lead to significant gains in throughput compared to system where PHY and MAC layers are designed separately and the wireless fading channels are abstracted as time invariant, fixed rate channels for scheduling purposes. We first consider opportunistic spectrum access in a cognitive radio network, where a secondary user (SU) share the spectrum opportunistically with incumbent primary users (PUs). Similar to earlier works on distributed opportunistic scheduling (DOS), we maximize the throughput of SU by formulating the channel access problem as a maximum rate-of-return problem in the optimal stopping theory framework. We show that the optimal channel access strategy is a pure threshold policy, namely the SU decides to use or skip transmission opportunities by comparing the channel qualities to a fixed threshold. We further increase the spectrum utilization by interleaving SU's packets with periodic sensing to detect PU's return. We jointly optimize the rate threshold and the packet transmission time to maximize the average throughput of SU, while limiting interference to PU. Next, we develop channel-aware opportunistic spectrum access strategies in a more general cognitive radio network with multiple SUs. Here, we additionally take into account the collisions and complex interaction between SUs and sharing of resources between them. We derive strategies for both cooperative settings where SUs maximize their sum total of throughputs, as well as non-cooperative game theoretic settings, where each SU tries to maximize its own throughput. We show that the optimal schemes for both scenarios are pure threshold policies. In the non-cooperative case, we establish the existence of Nash equilibrium and develop best response strategies that can converge to equilibria, with SUs relying only on their local observations. We study the trade-off between maximal throughput in the cooperative setting and fairness in the non-cooperative setting, and schemes based on utility functions and pricing that mitigate this tradeoff. In addition to maximizing throughput and fair sharing of resources, it is important to consider network/scheduling delays for QoS performance of delay-sensitive applications. We study DOS under both network-wide and user-specific average delay constraints. We take a stochastic Lagrangian approach and characterize the corresponding optimal scheduling policies accordingly, and show that they have a pure threshold structure. Next, we consider the use of different types of channel quality information, i.e., channel state information (CSI) and channel distribution information (CDI) in the opportunistic scheduling design for MIMO ad hoc networks. CSI is highly dynamic in nature and provides time diversity in the wireless channel, but is difficult to track. CDI offers temporal stability, but is incapable of capturing the instantaneous channel conditions. We design a new class of cross-layer opportunistic channel access scheduling framework for MIMO networks where CDI is used in the network context to group the simultaneous transmission links for spatial channel access and CSI is used in the link context to decide when and which link group should transmit based on a pre designed threshold. We thereby reap the benefits of both the temporal stability of CDI and the time diversity of CSI. Finally, we consider a novel application of cross layer optimization for communication of progressive coded images over OFDM wireless fading channels. We first consider adaptive modulation based on the instantaneous channel state information. An algorithm is proposed to allocate power and constellation size at each subchannel by maximizing the throughput. We next consider both the variance and the average of the throughput when deciding the constellation size for adaptive modulation. Simulation results confirm that cross-layer optimization with adaptive modulation enhances system performance.
Optimal Power Allocation For A Successive Refinable Source With Multiple Descriptions Over A Fading Relay Channel Using Broadcast Multicast Strategies
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Author : Kun Shi
language : en
Publisher:
Release Date : 2009
Optimal Power Allocation For A Successive Refinable Source With Multiple Descriptions Over A Fading Relay Channel Using Broadcast Multicast Strategies written by Kun Shi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
Security Privacy Trust And Resource Management In Mobile And Wireless Communications
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Author : Rawat, Danda B.
language : en
Publisher: IGI Global
Release Date : 2013-10-31
Security Privacy Trust And Resource Management In Mobile And Wireless Communications written by Rawat, Danda B. and has been published by IGI Global this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-10-31 with Computers categories.
"This book examines the current scope of theoretical and practical applications on the security of mobile and wireless communications, covering fundamental concepts of current issues, challenges, and solutions in wireless and mobile networks"--Provided by publisher.