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40
Optimization framework and graph-based approach for relay-assisted bidirectional OFDMA cellular networks
- IEEE Trans. Wireless Commun
, 2010
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Distributed Scheduling Scheme for Video Streaming over Multi-Channel Multi-Radio Multi-Hop Wireless Networks
- IEEE J. Select. Areas Commun
, 2010
"... Abstract—An important issue of supporting multi-user video streaming over wireless networks is how to optimize the system-atic scheduling by intelligently utilizing the available network resources while, at the same time, to meet each video’s Quality of Service (QoS) requirement. In this work, we st ..."
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Abstract—An important issue of supporting multi-user video streaming over wireless networks is how to optimize the system-atic scheduling by intelligently utilizing the available network resources while, at the same time, to meet each video’s Quality of Service (QoS) requirement. In this work, we study the problem of video streaming over multi-channel multi-radio multi-hop wireless networks, and develop fully distributed scheduling schemes with the goals of minimizing the video distortion and achieving certain fairness. We first construct a general distortion model according to the network’s transmission mechanism, as well as the rate distortion characteristics of the video. Then, we formulate the scheduling as a convex optimization problem, and propose a distributed solution by jointly considering channel assignment, rate allocation, and routing. Specifically, each stream strikes a balance between the selfish motivation of minimizing video distortion and the global performance of minimizing network congestions. Furthermore, we extend the proposed scheduling scheme by addressing the fairness problem. Unlike prior works that target at users ’ bandwidth or demand fairness, we propose a media-aware distortion-fairness strategy which is aware of the characteristics of video frames and ensures max-min distortion-fairness sharing among multiple video streams. We provide extensive simulation results which demonstrate the effectiveness of our proposed schemes. Index Terms—multi-channel multi-radio; video transmission; distributed scheduling; QoS; fairness. I.
XOR-Assisted Cooperative Diversity in OFDMA Wireless Networks: Optimization Framework and Approximation Algorithms
- IEEE INFOCOM 2009
, 2009
"... Abstract—Network coding has been leveraged with cooperative diversity to improve performance in single channel wireless networks. However, it is not clear how network coding based cooperative diversity can be exploited effectively in multi-channel networks where overhearing is not readily available. ..."
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Abstract—Network coding has been leveraged with cooperative diversity to improve performance in single channel wireless networks. However, it is not clear how network coding based cooperative diversity can be exploited effectively in multi-channel networks where overhearing is not readily available. Moreover, the question of how to practically realize the promising gains available, including multi-user diversity, cooperative diversity and network coding in multi-channel networks, also remains unexplored. This work represents the first attempt to unravel these two questions. In this paper, we propose XOR-CD, a novel XOR-assisted cooperative diversity scheme in OFDMA wireless networks. It can greatly improve the relay efficiency by over 100 % mostly, thus uplifting the throughput performance by over 30 % compared to conventional cooperative diversity scheme. In addition, we formulate a unifying optimization framework that jointly considers relay assignment, relay strategy selection, channel assignment and power allocation to reap different forms of gains. We design efficient polynomial time algorithms to solve the NP-hard problem with provably the best approximation factor, and verify their effectiveness using realistic simulations. I.
Effective Capacity of a Correlated Rayleigh Fading Channel
"... The next generation wireless networks call for quality of service (QoS) support. The effective capacity (EC) proposed by Wu and Negi provides a powerful tool for the design of QoS provisioning mechanisms. In their previous work, Wu and Negi derived a formula for effective capacity of a Rayleigh fadi ..."
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Cited by 6 (1 self)
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The next generation wireless networks call for quality of service (QoS) support. The effective capacity (EC) proposed by Wu and Negi provides a powerful tool for the design of QoS provisioning mechanisms. In their previous work, Wu and Negi derived a formula for effective capacity of a Rayleigh fading channel with arbitrary Doppler spectrum. However, their paper did not provide simulation results to verify the accuracy of the EC formula derived in their paper. This is due to difficulty in simulating a Rayleigh fading channel with a Doppler spectrum of continuous frequency, required by the EC formula. To address this difficulty, we develop a verification methodology based on a new discrete-frequency EC formula; different from the EC formula developed by Wu and Negi, our new discrete-frequency EC formula can be used in practice. Through simulation, we verify that the EC formula developed by Wu and Negi is accurate. Furthermore, to facilitate the application of the EC theory to the design of practical QoS provisioning mechanisms in wireless networks, we propose a spectral-estimation-based algorithm to estimate the EC function, given channel measurements; we also analyze the effect of spectral estimation error on the accuracy of EC estimation. Simulation results show that our proposed spectral-estimation-based EC estimation algorithm is accurate, indicating the excellent practicality of our algorithm.
Effective Capacity of a Correlated Nakagami-m Fading Channel
"... The grail of next-generation wireless networks is providing real-time services for delay-sensitive applications, which require that the wireless networks provide QoS guarantees. The effective capacity (EC) proposed by Wu and Negi provides a powerful tool for design of QoS provisioning mechanisms. In ..."
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Cited by 4 (1 self)
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The grail of next-generation wireless networks is providing real-time services for delay-sensitive applications, which require that the wireless networks provide QoS guarantees. The effective capacity (EC) proposed by Wu and Negi provides a powerful tool for design of QoS provisioning mechanisms. In this paper, we intend to generalize their formula for the effective capacity of a correlated Rayleigh fading channel; specifically, we derive a closed form approximate EC formula for a special correlated Nakagami-m fading channel, for which the inverse of the correlation coefficient matrix is tridiagonal. To verify its accuracy via simulation, we develop a Green-matrix based approach, which allows us to analytically obtain the effective capacity (given the joint probability density function of a correlated Nakagami-m fading channel) while being able to simulate the corresponding channel gain process. Simulation results show that our EC formula is accurate. Furthermore, to facilitate the application of the EC theory to the design of practical QoS provisioning mechanisms, we propose a simple algorithm for estimating the EC of an arbitrary correlated Nakagami-m fading channel, given channel measurements; simulation results demonstrate the accuracy of our proposed EC estimation algorithm, showing its suitability in practice.
On-demand based wireless resources trading for green communications
- IEEE INFOCOM 2011 Workshop on Green Communications and Networking
"... Abstract-The purpose of Green Communications is to reduce the energy consumption of the communication system as much as possible without compromising the quality of service (QoS) for users. An effective approach for Green Wireless Communications is On-Demand strategy, which scales power consumption ..."
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Abstract-The purpose of Green Communications is to reduce the energy consumption of the communication system as much as possible without compromising the quality of service (QoS) for users. An effective approach for Green Wireless Communications is On-Demand strategy, which scales power consumption with the volume and location of user demand. Applying the OnDemand Communications model, we propose a novel scheme -Wireless Resource Trading, which characterizes the trading relationship among different wireless resources for a given number of performance metrics. According to wireless resource trading relationship, different wireless resources can be consumed for the same set of performance metrics. Therefore, to minimize the energy consumption for given performance metrics, we can trade the other type of wireless resources for the energy resource under the demanded performance metrics. Based on the wireless resource trading relationship, we derive the optimal energy-bandwidth and energy-time wireless resource trading relationship for green wireless communications. We also develop an adaptive trading strategy by using different bandwidths or different delays for different transmission distances with available bandwidths and acceptable delay bounds in wireless networks. Our conducted simulations show that the energy consumption of wireless networks can be significantly reduced with our proposed wireless resources trading scheme.
Quality of Service in mobile ad hoc networks: a survey
"... Abstract: To support multimedia applications, it is desirable that an ad hoc network has a provision of Quality of Service (QoS). However, the provision of QoS in a mobile ad hoc network is a challenging task. In this paper, we present a review of the current research related to the provision of QoS ..."
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Abstract: To support multimedia applications, it is desirable that an ad hoc network has a provision of Quality of Service (QoS). However, the provision of QoS in a mobile ad hoc network is a challenging task. In this paper, we present a review of the current research related to the provision of QoS in an ad hoc environment. We examine issues and challenges involved in providing QoS in an ad hoc network. We discuss methods of QoS provisioning at different levels including those at the levels of routing, Medium Access Control (MAC), and cross layer. Also, we discuss schemes for admission control and scheduling that are proposed in the literature for the provision of QoS. We compare salient features of various solutions and approaches and point out directions for future work.
1Cross-Layer Optimization of Two-Way Relaying for Statistical QoS Guarantees
"... Abstract—Two-way relaying promises considerable improve-ments on spectral efficiency in wireless relay networks. While most existing works focus on physical layer approaches to exploit its capacity gain, the benefits of two-way relaying on upper layers are much less investigated. In this paper, we s ..."
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Abstract—Two-way relaying promises considerable improve-ments on spectral efficiency in wireless relay networks. While most existing works focus on physical layer approaches to exploit its capacity gain, the benefits of two-way relaying on upper layers are much less investigated. In this paper, we study the cross-layer design and optimization for delay quality-of-service (QoS) provisioning in two-way relay systems. Our goal is to find the optimal transmission policy to maximize the weighted sum throughput of the two users in the physical layer while guaranteeing the individual statistical delay-QoS requirement for each user in the datalink layer. This statistical delay-QoS requirement is characterized by the QoS exponent. By integrating the concept of effective capacity, the cross-layer optimization problem is equivalent to a weighted sum effective capacity maximization problem. We derive the jointly optimal power and rate adaptation policies for both three-phase and two-phase two-way relay protocols. Numerical results show that the proposed adaptive transmission policies can efficiently provide QoS guarantees and improve the performance. In addition, the throughput gain obtained by the considered three-phase and two-phase protocols over direct transmission is significant when the delay-QoS requirements are loose, but the gain diminishes at tight delay requirements. It is also found that, in the two-phase protocol, the relay node should be placed closer to the source with more stringent delay requirement. Index Terms—Cross-layer optimization, two-way relaying, quality-of-service (QoS), delay-bound violation probability, ef-
A Network Flow Approach to Throughput Maximization in Cooperative OFDMA Networks
, 2012
"... In wireless cooperative orthogonal frequency-division multiple-access (OFDMA) networks, it is important to adapt the transmission strategies for each user according to the network channel dynamics in order to optimize the overall system performance. The adaption involves transmission mode selection ..."
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In wireless cooperative orthogonal frequency-division multiple-access (OFDMA) networks, it is important to adapt the transmission strategies for each user according to the network channel dynamics in order to optimize the overall system performance. The adaption involves transmission mode selection (a user can choose from direct or cooperative transmission), subcarrier assignment, subcarrier pairing (the incoming and outgoing subcarriers at the relay for cooperative transmission need to be matched), relay selection, as well as power allocation and hence is highly challenging. Many previous works only consider a subset of the adaptation. In this paper, we tackle the joint optimization problem using a network flow approach. Specifically, we first show that for given power allocation, the combinatorial optimization problem of transmission mode selection, subcarrier assignment, relay selection and subcarrier pairing for the system total throughput maximization can be transformed into a minimum cost network flow (MCNF) problem with integer solutions. The linear optimal distribution (LOD) algorithm is applied to find the optimal solution in polynomial time. We then solve the mixed integer programming problem of the joint assignment and power allocation in an asymptotically optimal way in the dual domain. Simulation results show that the proposed algorithms can significantly enhance the overall system throughput.
QoS-Aware Power Allocations for Maximizing Effective Capacity Over Virtual-MIMO Wireless Networks
"... Abstract—To enable multiple mobile users to transmit their signals simultaneously over the same sub-channels, the virtual multiple-input multiple-output (V-MIMO) techniques can exploit the multiple-input multiple-output (MIMO) spectrum efficiency gain. Traditional V-MIMO transmission schemes mainly ..."
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Abstract—To enable multiple mobile users to transmit their signals simultaneously over the same sub-channels, the virtual multiple-input multiple-output (V-MIMO) techniques can exploit the multiple-input multiple-output (MIMO) spectrum efficiency gain. Traditional V-MIMO transmission schemes mainly focus on maximizing the throughput of grouped mobile users without taking into account the quality-of-service (QoS) provisionings. In this paper, we propose the optimal power allocation schemes with statistical QoS provisionings to maximize the effective capacity of non-collaborative/collaborative V-MIMO wireless networks, respectively. For non-collaborative V-MIMO wireless networks, the mobile users in one V-MIMO group transmit signals in-dependently over the same sub-channels. In the view point of existing mobile users, they solely occupy the sub-channels. Thus, the existing mobile users employ the QoS-driven single-user
