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We focus on the optimization of real-time multimedia transmission over 802.11-based ad hoc networks. In particular, we propose a simple and efficient cross-layer mechanism that considers both the channel conditions and characteristics of the media for dynamically selecting the transmission mode. This mechanism called media-oriented rate selection algorithm (MORSA) targets loss-tolerant applications...
We investigate the resource allocation problem for the downlink of a multiple-input multiple-output orthogonal frequency division multiple access (MIMO-OFDMA) system. The sum rate maximization itself cannot cope with fairness among users. Hence, we address this problem in the context of the utility-based resource allocation presented in earlier papers. This resource allocation method allows to enhance...
This article introduces a method for efficiently transmitting medium grain scalable video packets over a transmission path consisting of multiple wireless links. Medium grain scalability provides bit rate adaptation according to the available bit rate by dropping a number of video packets in the compressed bit stream. In other words, rate-distortion control can be achieved by means of packet transmission...
The prime focus of this study is in developing distributed algorithms for cognitive relaying with time incentive for multiple primary users (CRTI-M). CRTI-M is a symbiotic paradigm in which the incumbent primary users (PUs) of the spectrum, with weak transmission links, seek cooperation from the cognitive secondary user (SU) nodes in their vicinity, and in return reward them with an incentive time...
The purpose of this article is to analyze the impact of network coding in wireless networks. We consider a network coded ALOHA that performs bi-directional network coding over the ALOHA MAC protocol in a star topology network. The transmission probabilities of each outer node and the center node, and the target signal-to-interference-plus-noise ratio (SINR) are jointly optimized to achieve the maximum...
This paper considers a transmission control problem in network-coded two-way relay channels (NC-TWRC), where the relay buffers randomly arrived packets from two users, and the channels are assumed to be fading. The problem is modeled by a discounted infinite horizon Markov decision process (MDP). The objective is to find an adaptive transmission control policy that minimizes the packet delay, buffer...
EA-MAC protocol is proposed on the basis of SMAC protocol to remedy the shortcomings of SMAC. In the EA-MAC, node correlation analysis algorithm and traffic adaptive duty cycle mechanism are added. Meanwhile, the residual energy is introduced into the existing traffic adaptive back-off mechanism to measure the saving efficiency. In the node correlation algorithm, all network nodes are divided...
One fundamental tradeoff in the cross-layer design of a communications system is delay allocation. We study delay budget partitioning in a wireless multimedia system between two of the main components of delay: the queuing delay in the source encoder output buffer and the delay caused by the interleaver. In particular, we discuss how to apportion the fixed delay budget between the source encoder and...
In this paper, we investigate the cross-layer optimization problem of congestion and power control in cognitive radio ad hoc networks (CRANETs) under predictable contact constraint. To measure the uncertainty of contact between any pair of secondary users (SUs), we construct the predictable contact model by attaining the probability distribution of contact. In particular, we propose a distributed...
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