he Internet Technology series published three articles in the January and February 2001 issues on... more he Internet Technology series published three articles in the January and February 2001 issues on optical and wireless Internet. Continuing with this topic, the current issue contains three timely articles on optical transport and supporting technologies.
s Scrics Editors of the Internet Technology Series of IEEE Communications Magazille, we publ ishe... more s Scrics Editors of the Internet Technology Series of IEEE Communications Magazille, we publ ished a Call for Papers requcst for original tutorial papers on "IP in 2005 -Directions in Wireless and Optical Transport."
his issue brings to our readers two articles of consider-U able relevance to the changing face of... more his issue brings to our readers two articles of consider-U able relevance to the changing face of telecommunications. The article "Scalability Implications of Virtual Private Networks" by Jeremy D e Clercq and Olivier Paradiens addresses the scalability and security of virtual private networks (VPNs). The article "COPS-SLS: A Service Level Negotiation Protocol for Internet'' by Thi Mai Trang Nguyen, Nadia Boukhatem, Yacine Gharmi Doudane, and Guy Pujolle, discusses protocols, models, and architectures for the negotiation and enforcement of service levels and quality of service (00s). The reader of these articles may wish to consider their potential performance under various conditions, including extreme circumstances as well as the more ordinary negotiation of service level or establishment of a VPN. For example, events of the last year demonstrate the degree of dependence on open communications and the importance of survivable design over the entire spectrum of networking. New Internet protocols clearly must ensure the levels of robust communications that were understood by the designers of the original Internet. There has been substantial work in multiprotocol label switching (MPLS) reliability, and certainly the robustness of MPLS and policy protocols will be central to future work in these areas. Indeed, it should he noted that unmanaged voice over IP (VolP) can provision new service on an ad-hoc basis within roughly the same timcframe as recovery of highly managed PSTN services, and this suggests a greater robustness of the IP-based services.
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.
The effective bandwidth approximation is an attractive mechanism for performing call admission co... more The effective bandwidth approximation is an attractive mechanism for performing call admission control in ATM networks. We present a methodology for evaluating the effective bandwidth of arbitrary on/off sources. An arbitrary on/off source is described by a stochastic process which alternates between on and off periods that have arbitrary probability density functions. We present two approximate methods for evaluating the effective bandwidth of an arbitrary on/off source. The first method is based on moment matching of the on and off periods. The second method is called the bandwidth matching procedure and is considerably more efficient than the moment matching procedure.
We present an overview of the IEEE 802.17 Resilient Packet Ring (RPR) protocol standard for metro... more We present an overview of the IEEE 802.17 Resilient Packet Ring (RPR) protocol standard for metropolitan area networks. We discuss the main characteristics of the protocol and the main drivers for its development. We outline various aspects of the protocol: architecture and operation principles, physical layer, packet formats, the MAC protocol and its fairness, protection switching and topology discovery. We also discuss possible ways and technologies that could be used by a carrier to evolve its services and network architecture to meet the everincreasing demand for bandwidth in the metropolitan area.
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 ...
CDMA Mobile Radio Design CDMA Mobile Radio Design, J.B. Gore, L.E. Larson; Artech House Publisher... more CDMA Mobile Radio Design CDMA Mobile Radio Design, J.B. Gore, L.E. Larson; Artech House Publishers, 2000, ISBN 1580530591 This book is one of the most thorough books on CDMA technology as applied to mobile communications. It covers both the 2nd generation CDMA-based IS-95 standard as well as the 3rd generation W-CDMA (UMTS) and multicarrier CDMA (CDMA-2000). The main focus of the book is on the physical layer and communication transceiver design. The book does not address issues such as capacity planning and mobile system deployment issues (such as cell design, coverage, handoff handling etc). This does not represent any problem since the book is quite comprehensive in its category and in what it covers.
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 ...
We address the issue of reserving resources at packet switches along the path of connections requ... more We address the issue of reserving resources at packet switches along the path of connections requiring a deterministic end-to-end delay bound. The switches are assumed to schedule outgoing packets using either the Packet-by-Packet Generalized Processor Sharing (PGPS) or the Rate-Controlled Earliest-Deadline First (RC-EDF) scheduling disciplines. We propose a set of resource reservation policies that are used to map the end-to-end delay requirement into a local rate or local deadline to be reserved at each switch. We present simulation results to evaluate the performance of these resource allocation policies. For PGPS it is found that in general network topologies when shortest-path first routing is used, that uniform allocation performs better than other policies. In the case of RC-EDF, it is shown that non-uniform delay allocation policies provide resilient and superior performance over uniform allocation of resources. This is especially clear in networks with improper capacity planning or heterogeneous links.
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 ...
he Internet Technology series published three articles in the January and February 2001 issues on... more he Internet Technology series published three articles in the January and February 2001 issues on optical and wireless Internet. Continuing with this topic, the current issue contains three timely articles on optical transport and supporting technologies.
s Scrics Editors of the Internet Technology Series of IEEE Communications Magazille, we publ ishe... more s Scrics Editors of the Internet Technology Series of IEEE Communications Magazille, we publ ished a Call for Papers requcst for original tutorial papers on "IP in 2005 -Directions in Wireless and Optical Transport."
his issue brings to our readers two articles of consider-U able relevance to the changing face of... more his issue brings to our readers two articles of consider-U able relevance to the changing face of telecommunications. The article "Scalability Implications of Virtual Private Networks" by Jeremy D e Clercq and Olivier Paradiens addresses the scalability and security of virtual private networks (VPNs). The article "COPS-SLS: A Service Level Negotiation Protocol for Internet'' by Thi Mai Trang Nguyen, Nadia Boukhatem, Yacine Gharmi Doudane, and Guy Pujolle, discusses protocols, models, and architectures for the negotiation and enforcement of service levels and quality of service (00s). The reader of these articles may wish to consider their potential performance under various conditions, including extreme circumstances as well as the more ordinary negotiation of service level or establishment of a VPN. For example, events of the last year demonstrate the degree of dependence on open communications and the importance of survivable design over the entire spectrum of networking. New Internet protocols clearly must ensure the levels of robust communications that were understood by the designers of the original Internet. There has been substantial work in multiprotocol label switching (MPLS) reliability, and certainly the robustness of MPLS and policy protocols will be central to future work in these areas. Indeed, it should he noted that unmanaged voice over IP (VolP) can provision new service on an ad-hoc basis within roughly the same timcframe as recovery of highly managed PSTN services, and this suggests a greater robustness of the IP-based services.
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.
The effective bandwidth approximation is an attractive mechanism for performing call admission co... more The effective bandwidth approximation is an attractive mechanism for performing call admission control in ATM networks. We present a methodology for evaluating the effective bandwidth of arbitrary on/off sources. An arbitrary on/off source is described by a stochastic process which alternates between on and off periods that have arbitrary probability density functions. We present two approximate methods for evaluating the effective bandwidth of an arbitrary on/off source. The first method is based on moment matching of the on and off periods. The second method is called the bandwidth matching procedure and is considerably more efficient than the moment matching procedure.
We present an overview of the IEEE 802.17 Resilient Packet Ring (RPR) protocol standard for metro... more We present an overview of the IEEE 802.17 Resilient Packet Ring (RPR) protocol standard for metropolitan area networks. We discuss the main characteristics of the protocol and the main drivers for its development. We outline various aspects of the protocol: architecture and operation principles, physical layer, packet formats, the MAC protocol and its fairness, protection switching and topology discovery. We also discuss possible ways and technologies that could be used by a carrier to evolve its services and network architecture to meet the everincreasing demand for bandwidth in the metropolitan area.
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 ...
CDMA Mobile Radio Design CDMA Mobile Radio Design, J.B. Gore, L.E. Larson; Artech House Publisher... more CDMA Mobile Radio Design CDMA Mobile Radio Design, J.B. Gore, L.E. Larson; Artech House Publishers, 2000, ISBN 1580530591 This book is one of the most thorough books on CDMA technology as applied to mobile communications. It covers both the 2nd generation CDMA-based IS-95 standard as well as the 3rd generation W-CDMA (UMTS) and multicarrier CDMA (CDMA-2000). The main focus of the book is on the physical layer and communication transceiver design. The book does not address issues such as capacity planning and mobile system deployment issues (such as cell design, coverage, handoff handling etc). This does not represent any problem since the book is quite comprehensive in its category and in what it covers.
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 ...
We address the issue of reserving resources at packet switches along the path of connections requ... more We address the issue of reserving resources at packet switches along the path of connections requiring a deterministic end-to-end delay bound. The switches are assumed to schedule outgoing packets using either the Packet-by-Packet Generalized Processor Sharing (PGPS) or the Rate-Controlled Earliest-Deadline First (RC-EDF) scheduling disciplines. We propose a set of resource reservation policies that are used to map the end-to-end delay requirement into a local rate or local deadline to be reserved at each switch. We present simulation results to evaluate the performance of these resource allocation policies. For PGPS it is found that in general network topologies when shortest-path first routing is used, that uniform allocation performs better than other policies. In the case of RC-EDF, it is shown that non-uniform delay allocation policies provide resilient and superior performance over uniform allocation of resources. This is especially clear in networks with improper capacity planning or heterogeneous links.
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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