The Experts below are selected from a list of 27615 Experts worldwide ranked by ideXlab platform
Chang Wen Chen - One of the best experts on this subject based on the ideXlab platform.
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a cross layer approach to multichannel mac protocol design for video streaming over wireless ad hoc networks
IEEE Transactions on Multimedia, 2009Co-Authors: Chang Wen ChenAbstract:This paper presents a cross-layer design for a reliable video transmission over wireless ad hoc networks based on multichannel MAC protocol with TDMA. First, we conduct a study of the multichannel MAC protocol through Markov chain model. Based on this study, two novel cross-layer modules are adopted for the design of multichannel MAC protocol. First, we adopt maximum latency rate (MLR) as the channel quality metric. Unlike the traditional MAC design based on network allocation vector (NAV), MLR is implemented to provide differentiated Traffic so that the channel with smaller MLR time is initiated for higher Priority Traffic. Second, we adopt two congestion-aware metrics, namely MAC utilization and queue length of MAC layer, to improve the congestion-aware routing protocols with AODV and DSR. These two novel modules allow the proposed MAC protocol design to achieve high performance video transmission over wireless ad hoc networks. Experimental results show that the proposed scheme outperforms the state-of-the-art schemes under multichannel environments in wireless ad hoc networks for as much as 3.6 dB in PSNR. Such significant performance enhancement confirms that the cross-layer approach is very effective for multichannel MAC protocol design.
T. Agarwal - One of the best experts on this subject based on the ideXlab platform.
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Dynamic tuning of the maximum contention window (CWmax) for enhanced service differentiation in IEEE 802.11 wireless ad-hoc networks
IEEE 60th Vehicular Technology Conference 2004. VTC2004-Fall. 2004, 2024Co-Authors: L. Gannoune, Stephan Robert, N. Tomar, T. AgarwalAbstract:The proposed IEEE 802.11e draft standard defines new MAC protocols for QoS in wireless networks, mainly EDCF and HCF. In this paper, we propose to extend EDCF with a dynamic adaptation algorithm of the maximum contention window (CWmax) that enables each station to tune the size of the CWmax used in its back-off algorithm at run time. The purpose of our scheme is to reduce delay and jitter and increases the efficiency of the transmission channel. Priorities between access categories are provisioned by updating the size of the CWmax according to application requirements and channel conditions. The performance of the enhanced EDCF are extensively investigated by simulation. Results obtained indicate that the delay and jitter for high Priority Traffic, i.e., audio Traffic, improve and delay decreases by up to 43%. Furthermore, delay for lower Priority Traffic, e.g., video Traffic, remains stable. Throughput in CWmax adaptation, compared to EDCF, is stable in light and medium system load and increases by up to 7% especially at high system load.
Mustafa Mehmetali - One of the best experts on this subject based on the ideXlab platform.
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performance modeling of message dissemination in vehicular ad hoc networks with Priority
IEEE Journal on Selected Areas in Communications, 2011Co-Authors: Mehdi Khabazian, Sonia Aissa, Mustafa MehmetaliAbstract:In this paper, we present an analytical study for the performance of message dissemination in vehicular ad hoc networks (VANETs) with two Priority classes. It is assumed that the message Traffic generated by event-driven safety applications has higher Priority compared to the remaining network Traffic. First, we derive the distribution of the number of concurrent transmissions of lower Priority messages in the system at the steady state, through a birth-death process analysis. The distribution has a simple product form solution. We also derive the percentage of destination node population which cannot receive the message error free due to interference. Subsequently, we determine the average forwarding distance and the number of nodes which receive a high-Priority message in the presence of low-Priority Traffic. Numerical results are provided along with simulation results that confirm the accuracy of the proposed analysis. The distribution of the number of concurrent transmissions is shown to have a bell-shape curve. Results also show that larger transmission ranges do not necessarily improve the per hop safety-message forwarding distance as more nodes may be exposed to interference, especially in networks with higher node densities.
L. Gannoune - One of the best experts on this subject based on the ideXlab platform.
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Dynamic tuning of the maximum contention window (CWmax) for enhanced service differentiation in IEEE 802.11 wireless ad-hoc networks
IEEE 60th Vehicular Technology Conference 2004. VTC2004-Fall. 2004, 2024Co-Authors: L. Gannoune, Stephan Robert, N. Tomar, T. AgarwalAbstract:The proposed IEEE 802.11e draft standard defines new MAC protocols for QoS in wireless networks, mainly EDCF and HCF. In this paper, we propose to extend EDCF with a dynamic adaptation algorithm of the maximum contention window (CWmax) that enables each station to tune the size of the CWmax used in its back-off algorithm at run time. The purpose of our scheme is to reduce delay and jitter and increases the efficiency of the transmission channel. Priorities between access categories are provisioned by updating the size of the CWmax according to application requirements and channel conditions. The performance of the enhanced EDCF are extensively investigated by simulation. Results obtained indicate that the delay and jitter for high Priority Traffic, i.e., audio Traffic, improve and delay decreases by up to 43%. Furthermore, delay for lower Priority Traffic, e.g., video Traffic, remains stable. Throughput in CWmax adaptation, compared to EDCF, is stable in light and medium system load and increases by up to 7% especially at high system load.
Mehdi Khabazian - One of the best experts on this subject based on the ideXlab platform.
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performance modeling of message dissemination in vehicular ad hoc networks with Priority
IEEE Journal on Selected Areas in Communications, 2011Co-Authors: Mehdi Khabazian, Sonia Aissa, Mustafa MehmetaliAbstract:In this paper, we present an analytical study for the performance of message dissemination in vehicular ad hoc networks (VANETs) with two Priority classes. It is assumed that the message Traffic generated by event-driven safety applications has higher Priority compared to the remaining network Traffic. First, we derive the distribution of the number of concurrent transmissions of lower Priority messages in the system at the steady state, through a birth-death process analysis. The distribution has a simple product form solution. We also derive the percentage of destination node population which cannot receive the message error free due to interference. Subsequently, we determine the average forwarding distance and the number of nodes which receive a high-Priority message in the presence of low-Priority Traffic. Numerical results are provided along with simulation results that confirm the accuracy of the proposed analysis. The distribution of the number of concurrent transmissions is shown to have a bell-shape curve. Results also show that larger transmission ranges do not necessarily improve the per hop safety-message forwarding distance as more nodes may be exposed to interference, especially in networks with higher node densities.
