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The rise of machine-to-machine communications has rekindled interest in random access protocols as a support for a massive number of uncoordinatedly transmitting devices. The legacy ALOHA approach is developed under a collision model, where slots containing collided packets are considered as waste. However, if the common receiver (e.g. base station) is able to store the collision slots and use them in a transmission recovery process based on successive interference cancellation, the design space for access protocols is radically expanded. We present the paradigm of coded random access, in which the structure of the access protocol can be mapped to a structure of an erasure-correcting code defined on a graph. This opens the possibility to use coding theory and tools for designing efficient random access protocols, offering markedly better performance than ALOHA. Several instances of coded random access protocols are described, as well as a case study on how to upgrade a legacy ALOHA system using the ideas of coded random access. [ABSTRACT FROM PUBLISHER]

In this article we illustrate the performance of Transmission Control Protocol in an overlay cognitive radio network under dynamic spectrum access. We show that the performance of TCP in overlay CR networks that implement DSA to be quite different from its performance in conventional networks, which do not allow DSA. The key difference is that secondary users in an overlay CR network have to cope with a new type of loss called service interruption loss, due to the existence of primary users. We demonstrate on an NS2 simulation testbed the surprising result: Excessive radio resource usage leads to a decrease in aggregate TCP throughput. This behavior is in contrast to the behavior of TCP in conventional networks, where throughput increases monotonically with the available radio resource. [ABSTRACT FROM AUTHOR]

Modeling and simulation methods are employed by scientists and engineers to gain insight into system behavior that can lead to faster product time-to-market and more robust designs. These advantages come at the cost of model development time and the potential for questionable results because the model represents limited attributes of the actual system. M&S techniques are used to characterize complex interactions and performance at various layers of the protocol stack. This article provides a discussion of M&S for wireless network designers and developers, with particular attention paid to the architectural issues, as well as a discussion of the various communication M&S tools available today. The topics presented span the protocol stack, including radio-frequency-propagation M&S tools, physical-layer and waveform M&S, network-layer M&S, and distributed simulation, as well as waveform generation for test and evaluation. [ABSTRACT FROM AUTHOR]

Ethernet technologies are rapidly gaining importance as a prevailing solution for carrier networks. Ethernet ring protection switching, defined in ITU-T Recommendation G.8032, provides a means of achieving carrier network requirements for ring network topologies. This article outlines the novel concepts in this Ethernet ring protection switching mechanism and discusses the fundamental operating principles by which the automatic protection switching (APS) protocol works. In addition, several feature enhancements in protection behavior and solutions being considered for the next phase of standardization are discussed. [ABSTRACT FROM AUTHOR]

As data rates outpace the capabilities of electronic encryption schemes, photonic layer security may fill the gap in providing a communication security solution at high data rates. In this article we review and highlight the advantages of our proposed optical code-division multiplexed (OCDM)-based photonic layer security (PLS) system based on high-resolution control of the optical phase of tightly spaced phase locked laser lines. Such a PLS system is scaleable to 100 Gb/s and provides a protocol independent security solution. We review the use of high-resolution control of the optical phase of mode-locked laser frequency combs as an enabling technology for a new class of OCDM systems. A network based on such systems is compatible with and can have comparable spectral efficiency to existing DWDM networks. Through inverse multiplexing of 10 Gb/s tributaries, we have already demonstrated optical transmission of a 40 Gb/s aggregate OCDM signal over 400 km. Such a PLS solution is achieved through shared phase scrambling of the individual OCDM codes assigned to each of the tributaries using an integrated micro-ring resonator-based phase coder/scrambler. The confidentiality of OCDM-based PLS is robust against exhaustive, known plain text, and archival/forensic attacks, and can complement digital encryption operating at higher layers. Moreover, the integrity of the PLS solution is ensured through the inherent coupling to confidentiality, since knowledge of the key is needed in order to easily alter the transmitted data stream without introducing observable errors. This system can leverage advances in optical integration to support new applications where electronic encryption is impractical because of space, weight, power, availability, and cost requirements. Such applications range from timely security support for the emerging 100 GbE standards to all-optical multilevel security offered through the compatibility of PLS with transparent DWDM networks. [ABSTRACT FROM AUTHOR]

The article examines a possible way of improving the performance of the presence service within IMS networks without modifying the presence and group management enabler. This can be achieved by means of a presence network agent (PNA). The PNA has been defined by 3GPP in [1]; it is a new logic entity within the IMS core network that is able to publish the presence information on behalf of the presentity user agent. The PNA improves performance because it reduces the presence signaling load within the radio access network without downgrading the freshness and richness of the presence information. The article's goal is to provide the reader with useful information about the PNA and our experience with PNA implementation and deployment. We first describe the PNA concept as defined by 3GPP, highlighting the open issues still present in the standardization and the possible optimizations, subsequently we present an actual implementation of a PNA handling busy/idle states for IMS calls. [ABSTRACT FROM AUTHOR]

In this article, a new Internet broadcasting scheme that combines the existing network-wide unicast protocol and a subnet-wide broadcast protocol is proposed. The proposed broadcasting scheme is appropriate for location-based push services and requires only a minor functional addition to the existing edge routers, base stations, or access points. To eliminate unnecessary broadcasting traffic, an efficient terminal-originated triggering algorithm for broadcast initiation is introduced. The scheme provides location-based information to mobile users without the need for protocol reconfigurations or prior knowledge of a user's location. We also discuss some potential applications of the scheme. Performance of the proposed scheme has been evaluated and selected results are presented in this article. The evaluation shows that the broadcasting scheme significantly reduces the network traffic and the server load. [ABSTRACT FROM AUTHOR]

For label switched networks, such as MPLS and GMPLS, most existing traffic engineering solutions work in a single routing domain. These solutions do not work when a route from the ingress node to the egress node leaves the routing area or autonomous system of the ingress node. In such cases, the path computation problem becomes complicated because of the unavailability of the complete routing information throughout the network. This is because service providers usually choose not to leak routing information beyond the routing area or AS for scalability constraints and confidentiality concerns. This article serves two purposes. First, it provides a description of the existing and ongoing work in interdomain TE within the IETF. This information is currently found in various Internet drafts and has not yet been collectively presented in a single document. To this end, a summary of both existing path computation architectures — PCE-based and per-domain — is provided. Second, it compares two per-domain path computation schemes in terms of the total number of LSPs successfully placed and average number of domains crossed, without assuming availability of complete topology information. We notice that the two per-domain path computation schemes, proposed in [1, 2], have comparable path computation complexities and setup latencies. [ABSTRACT FROM AUTHOR]

Automatic resource discovery plays a significant role in next-generation optical networks, where nodes can maintain a large number of input/output ports (fibers, wavelengths, time slots, etc.). This automation avoids long and tedious manual node configurations and minimizes resource misconfiguration probability, which can result in high cost savings for network operators. The generalized multiprotocol label sswitching (GMPLS) Link Management Protocol (LMP) has been defined to provide such functionalities. However, it requires optical nodes to transmit in-band information, thus requesting link termination on each incoming port. This issue, in transparent optical networks, implies additional hardware, high complexities, or even signal losses. This article proposes and evaluates novel extensions to standard LMP that cope with the discovery of all-optical transport planes. In addition, playing a crucial role in ASON/GMPLS networks, this article also generically covers the automatic discovery of the control plane. [ABSTRACT FROM AUTHOR]

Two articles under the same title, "Telecommunications in Russia," were published in IEEE Communications Magazine in 1992 and 2000, respectively [1, 2]. From the beginning of this century Russian telecommunications has undergone significant changes. Some of them related to mobile networks and Internet are briefly described in this article. [ABSTRACT FROM AUTHOR]

This article presents the technical details of the Extensible Authentication Protocol (EAP) and IEEE 802.1x by using WIRE1x, an open-source implementation of IEEE 802.1x client (supplicant) and various EAP-based authentication mechanisms. By using a real implementation, 802.1x and EAP should be easily understood. [ABSTRACT FROM AUTHOR]

Configuration management is critical to correct and efficient operation of large networks. Where the users and networks are dynamic and ad hoc, manual configuration quickly becomes too complex. The combination of the sheer number of nodes with heterogeneity and dynamics makes it almost impossible for the system administrator to ensure good configuration or even correct operation. To achieve the vision of pervasive computing, nodes must automatically discover their environment and self-configure, then automatically reconfigure to adapt to changes. Protocols such as DHCP, DDNS, and mDNS provide some degree of host autoconfiguration, but network administrators must still configure information such as address pools, routing protocols, and OSPF routing areas. Only limited progress has been made in automating the configuration of routers, servers, and network topology. We propose the first unified attempt to combine both self-configuration of much of the host, router, and server information with automatic generation and maintenance of hierarchy under the same algorithmic framework. Testbed implementations show the approach is practical, while simulations reveal its scalability, rapidity, and efficiency with respect to network performance. [ABSTRACT FROM AUTHOR]

This article describes a recent R&D result in supporting secure and dynamic coalition inter-networking scenarios, where a number of military and civil subnetworks are combined using IPsec in a higher-level IP secure military network. It is part of the work undertaken in the VPN Workshop initiative, where a set of national defense and research organizations are meeting together to align their vision and requirements on what an IPv4 or IPv6 secure and dynamic IPsec-based virtual private network should be, and how to deploy it in an international multidomain scenario. [ABSTRACT FROM AUTHOR]

IPv6 extends capabilities of legacy IPv4 networks. The advantages of IPv6, however, come at the cost of increased operational overhead. As government networks providing services to the global information grid (GIG) migrate toward an IPv6-based infrastructure, the implications of an expanded packet header must be analyzed. This article describes two IPv6 applicable header compression schemes developed by the IETF, and how networks across the GIG infrastructure can adopt them in an effort to reduce IPv6 expanded overhead requirements. [ABSTRACT FROM AUTHOR]

In the migration toward network-centric warfare, the NATO STANAG 4406 for Military Message Handling Systems (MMHS) may be used for direct information exchange between high-data-rate strategic users and low-data-rate tactical users by utilizing its new tactical protocol profile. In this article the protocol profiles are tested across a "worst case" tactical HF link providing IP services. There are considerable throughput gains available using the tactical pro- file. Among the various automated HF technologies tested, the new HDL+ data link protocol, suggested for standardization within NATO, shows the best throughput capabilities for short to medium-size messages on typical HF channels. 3G HF is the most robust technology at low signal-to-noise ratios. The 2G HF throughput performance suffers from inefficient linking procedures. There are optimization issues at different levels of the protocol stack, and implementation choices have great impact on overall performance. [ABSTRACT FROM AUTHOR]

The high demand for wireless Internet Connectivity has driven the development of highly efficient radio link technologies. However, their performance can be compromised by inadvertent interactions with the higher-layer TCP flow Control protocol. Maximizing the performance of wireless links requires that mechanisms operating at every layer of the protocol stack interact efficiently. This article provides a brief tutorial of some of these radio link enhancements. It then outlines how higher-layer flow control protocols should behave, and provides techniques for taming the behavior of TCP, to ensure that the performance of lower-layer enhancements is not compromised. [ABSTRACT FROM AUTHOR]

Discusses several modifications to the core congestion control algorithms in transmission control protocol (TCP). Changes to the congestion control mechanisms of TCP; Components of TCP congestion control; Impact of explicit congestion notification on TCP congestion control.

Explains how optimizations below and above the transmission control protocol (TCP) stack can allow hosts to run TCP at gigabit speed. Techniques in low-overhead networking; Role of the network interface; Experimental system for high-speed TCP.

Identifies the fundamental reasons for transmission control protocol performance degradation over asymmetric computer networks. Forms of network asymmetry; Information on uplink bandwidth management; How to handle infrequent acknowledgement packets.

Describes an approach to the design of control planes for optical crossconnects (OXC) based on the multiprotocol label switching (MPLS) traffic engineering control plane. Advantages of the proposed approach; Requirements for the OXC control plane; Extremal architectural options for the deployment of the proposed control plane.

Proposes a single-server-view network paradigm for 21st century communications networks. Description of the network architecture; Information on photonic network; Key agent technology functions of the proposed network.

Describes a quality of service (QoS) network that combines RSVP signaling protocol and differentiated services. Taxonomy for QoS mechanisms; Reasons for the previous failure of the application of RSVP and Intserv in QoS networks; Evolution of several major QoS mechanisms.

Describes the approaches used to improve the performance of STREAMS-based networking protocol stacks. Discussion on the architecture of STREAMS; Inefficiencies of STREAMS mechanisms; Evaluation on the outcome of the approaches.

Focuses on the characteristics of transmission media carrying Internet traffic. Importance of Transmission Control Protocol (TCP); Characteristics of TCP degradation; Discussion on the problems on Internet transmission media; Suggestions on how to solve the problems.

Presents information on a programmable architecture for the provision of hybrid communication services. Background on hybrid services; Principles of the service architecture and its advantages; Generic service components for the creation of sophisticated services; Presentation of a hybrid closed user group design.

Gives a glimpse of the topics in focus and technology on exhibit at SUPERCOMM '99, a communications exhibition and conference. Guests and speakers; Ideas on network migration technology from AT&T's Michael Gerwirtz; Hugh Bradlow's views on Internet Protocol (IP) and changes in the existing infrastructures' processes and systems.

Discusses a research project conducted by the French National Telecommunications Research Network that defined and developed the traffic handling and dimensioning rules needed to optimize traffic engineering or data flows in Internet Protocol (IP) networks as of May 2002. IP network services being defined by the project; Tasks involved in characterizing the different traffic categories to be found in a multimedia network.

Presents news briefs from the telecommunication industry in the United States as of March 2000. Features of eLink Agent, a wireless device from American Mobile; Information on Internet Protocol Network Configurator, an Internet protocol from Lucent Technologies; Offerings of Gig E service, a Gigabit Ethernet-based data service from Exodus Communications.