Optical packet switching (OPS) is a promising technology to enable next-generation high-speed IP ... more Optical packet switching (OPS) is a promising technology to enable next-generation high-speed IP networks. A major issue in OPS is packet contention that occurs when two or more packets attempt to access the same output fiber. In such a case, packets may be dropped, leading to degraded overall switching performance. Several contention resolution techniques have been investigated in the literature including the use of fiber delay lines (FDLs), wavelength converters (WCs), and deflection routing. These solution typically induce extra complexity to the switch design. Accordingly, a key design objective for OPS is to reduce packet loss without increasing switching complexity and delay. In this paper, we investigate the performance of contention resolution in asynchronous OPS architectures with shared FDLs and WCs in terms of packet loss and average switching delay. In particular, an enhanced FDL-based and a novel Hybrid architecture with shared FLDs and WCs are proposed, and their packet scheduling algorithms are presented and evaluated. Extensive simulation studies show that the performance of proposed FDL-based architecture outperforms typical OPS architectures reported in the literature. In addition, it shown that, for the same packet loss ratio, the proposed hybrid architecture can achieve up to 30% reduction in the total number of ports and around 80% reduction in the overall length of fiber as compared to the FDL-based architectures.
Directional antennas are well known for being capable of performance improvement in wireless ad-h... more Directional antennas are well known for being capable of performance improvement in wireless ad-hoc networks. In the IEEE 802.11 MAC protocol when two nodes are communicating with each other, all other nodes in the transmission zone are required to remain idle. With the use of directional antennas, it is possible to have two pairs of nodes located in each other's transmission range to communicate simultaneously; this increases the spatial reuse of the wireless channel. However, directional antennas suffer from deafness and hidden terminal problems and therefore new mechanisms are required for exploitation of the directional antennas in an intelligent manner. In this paper we present a scheme based on switched beam directional antenna with busy tone for controlling the directional antenna beams for maximum spatial reuse and saving in energy consumption. The purpose of the busy tone signal is to inform nodes in the transmission zone about the current transmission which helps solving hidden terminal and deafness problems. We present performance evaluation results which confirm the significant improvement in both throughput and energy consumption. We also study the effect of the number of beams on the throughput and energy consumption.
Page 1. Parallel Algorithms for the Orthogonal Multiprocessor Khaled MF Elsayed Department of Com... more Page 1. Parallel Algorithms for the Orthogonal Multiprocessor Khaled MF Elsayed Department of Computer Science North Carolina State University, Raleigh, NC 27695-8207 khaled@zeus.csc.ncsu.edu Abstract The orthogonal ...
Earliest deadline first (EDF) schedulers are known to be optimal with respect to achieving delay ... more Earliest deadline first (EDF) schedulers are known to be optimal with respect to achieving delay bounds in the single node case. For a session traversing a multi-node network, applying EDF schedulability condition at each node separately leads to very restrictive admission control policy for delay sensitive applications. Other scheduling disciplines such as PGPS, that take into account the delay dependency in the network, outperform EDF in such situations. We present a heuristic method to enhance the schedulability condition for EDF schedulers as compared to PGPS. The method is based on matching the delay bound obtained by EDF schedulers and PGPS schedulers in a homogeneous network of nodes where all sessions traverse the same number of hops and require the same maximum delay. The method leads to enhancing the performance of the EDF schedulers in a multi-node network. Our simulation results show that the method works well in practice
Page 1. Dimensioning of Communication Links for Base-station and MSC Interconnection in CDMA Mobi... more Page 1. Dimensioning of Communication Links for Base-station and MSC Interconnection in CDMA Mobile Communication Systems Khaled M. F. Elsayed, Member IEEE Faculty of Engineering, Cairo University Department of ...
Connection Admission Control (CAC) is one of the primary mechanisms for preventive congestion con... more Connection Admission Control (CAC) is one of the primary mechanisms for preventive congestion control and bandwidth allocation in ATM networks. A substantial number of CAC schemes have been proposed. In this paper, we review the salient features of some of these algorithms. We also provide a comparative study of the performance of CAC schemes devised to meet certain quality of
Page 1. Analysis of a Statistical Multiplexer with Heterogenous Markovian On/Off Sources and Appl... more Page 1. Analysis of a Statistical Multiplexer with Heterogenous Markovian On/Off Sources and Applications to Call Admission Control in ATM Networks а Khaled M. Elsayed Harry G. Perros Department of Computer Science and ...
Page 1. Multi-objective Resource Allocation for the band-AMC IEEE 802.16 Downlink with Proportion... more Page 1. Multi-objective Resource Allocation for the band-AMC IEEE 802.16 Downlink with Proportional Rate Constraints Mina AA Sokar Electronics and Communications Engineering Dept. Cairo University Giza, Egypt m.sokar@ieee.org ...
Page 1. A Steiner-Tree Based Information-Directed Routing Scheme for Tracking Multiple Moving Tar... more Page 1. A Steiner-Tree Based Information-Directed Routing Scheme for Tracking Multiple Moving Targets Dina Reda Salem Department of Geomatics Engineering University of Calgary Calgary, AB, Canada dina.salem@ucalgary.ca ...
Optical packet switching (OPS) is a promising technology to enable next-generation high-speed IP ... more Optical packet switching (OPS) is a promising technology to enable next-generation high-speed IP networks. A major issue in OPS is packet contention that occurs when two or more packets attempt to access the same output fiber. In such a case, packets may be dropped, leading to degraded overall switching performance. Several contention resolution techniques have been investigated in the literature including the use of fiber delay lines (FDLs), wavelength converters (WCs), and deflection routing. These solution typically induce extra complexity to the switch design. Accordingly, a key design objective for OPS is to reduce packet loss without increasing switching complexity and delay. In this paper, we investigate the performance of contention resolution in asynchronous OPS architectures with shared FDLs and WCs in terms of packet loss and average switching delay. In particular, an enhanced FDL-based and a novel Hybrid architecture with shared FLDs and WCs are proposed, and their packet scheduling algorithms are presented and evaluated. Extensive simulation studies show that the performance of proposed FDL-based architecture outperforms typical OPS architectures reported in the literature. In addition, it shown that, for the same packet loss ratio, the proposed hybrid architecture can achieve up to 30% reduction in the total number of ports and around 80% reduction in the overall length of fiber as compared to the FDL-based architectures.
Directional antennas are well known for being capable of performance improvement in wireless ad-h... more Directional antennas are well known for being capable of performance improvement in wireless ad-hoc networks. In the IEEE 802.11 MAC protocol when two nodes are communicating with each other, all other nodes in the transmission zone are required to remain idle. With the use of directional antennas, it is possible to have two pairs of nodes located in each other's transmission range to communicate simultaneously; this increases the spatial reuse of the wireless channel. However, directional antennas suffer from deafness and hidden terminal problems and therefore new mechanisms are required for exploitation of the directional antennas in an intelligent manner. In this paper we present a scheme based on switched beam directional antenna with busy tone for controlling the directional antenna beams for maximum spatial reuse and saving in energy consumption. The purpose of the busy tone signal is to inform nodes in the transmission zone about the current transmission which helps solving hidden terminal and deafness problems. We present performance evaluation results which confirm the significant improvement in both throughput and energy consumption. We also study the effect of the number of beams on the throughput and energy consumption.
Page 1. Parallel Algorithms for the Orthogonal Multiprocessor Khaled MF Elsayed Department of Com... more Page 1. Parallel Algorithms for the Orthogonal Multiprocessor Khaled MF Elsayed Department of Computer Science North Carolina State University, Raleigh, NC 27695-8207 khaled@zeus.csc.ncsu.edu Abstract The orthogonal ...
Earliest deadline first (EDF) schedulers are known to be optimal with respect to achieving delay ... more Earliest deadline first (EDF) schedulers are known to be optimal with respect to achieving delay bounds in the single node case. For a session traversing a multi-node network, applying EDF schedulability condition at each node separately leads to very restrictive admission control policy for delay sensitive applications. Other scheduling disciplines such as PGPS, that take into account the delay dependency in the network, outperform EDF in such situations. We present a heuristic method to enhance the schedulability condition for EDF schedulers as compared to PGPS. The method is based on matching the delay bound obtained by EDF schedulers and PGPS schedulers in a homogeneous network of nodes where all sessions traverse the same number of hops and require the same maximum delay. The method leads to enhancing the performance of the EDF schedulers in a multi-node network. Our simulation results show that the method works well in practice
Page 1. Dimensioning of Communication Links for Base-station and MSC Interconnection in CDMA Mobi... more Page 1. Dimensioning of Communication Links for Base-station and MSC Interconnection in CDMA Mobile Communication Systems Khaled M. F. Elsayed, Member IEEE Faculty of Engineering, Cairo University Department of ...
Connection Admission Control (CAC) is one of the primary mechanisms for preventive congestion con... more Connection Admission Control (CAC) is one of the primary mechanisms for preventive congestion control and bandwidth allocation in ATM networks. A substantial number of CAC schemes have been proposed. In this paper, we review the salient features of some of these algorithms. We also provide a comparative study of the performance of CAC schemes devised to meet certain quality of
Page 1. Analysis of a Statistical Multiplexer with Heterogenous Markovian On/Off Sources and Appl... more Page 1. Analysis of a Statistical Multiplexer with Heterogenous Markovian On/Off Sources and Applications to Call Admission Control in ATM Networks а Khaled M. Elsayed Harry G. Perros Department of Computer Science and ...
Page 1. Multi-objective Resource Allocation for the band-AMC IEEE 802.16 Downlink with Proportion... more Page 1. Multi-objective Resource Allocation for the band-AMC IEEE 802.16 Downlink with Proportional Rate Constraints Mina AA Sokar Electronics and Communications Engineering Dept. Cairo University Giza, Egypt m.sokar@ieee.org ...
Page 1. A Steiner-Tree Based Information-Directed Routing Scheme for Tracking Multiple Moving Tar... more Page 1. A Steiner-Tree Based Information-Directed Routing Scheme for Tracking Multiple Moving Targets Dina Reda Salem Department of Geomatics Engineering University of Calgary Calgary, AB, Canada dina.salem@ucalgary.ca ...
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