Search

Policy-based management allows the deployment of networks offering quality services in environments beyond the reach of real-time human control. A policy-based protocol stack middleware, the context-aware broker, has been developed by the authors to autonomically manage the remote deep space network. In this article example policy rules demonstrate the concept, and prototype results from ns-2.30 show the overall positive costbenefit impact in an example scenario. [ABSTRACT FROM AUTHOR]

This article investigates distributed cooperative medium access control protocol design for multihop wireless networks. Cooperative communication has been proposed recently as an effective way to mitigate channel impairments. With cooperation, single-antenna mobile terminals in a multi-user environment share antennas from other mobiles to generate a virtual multiple-antenna system that achieves more reliable communication with a higher diversity gain. However, more mobiles conscribed for one communication inevitably induces complex medium access interactions, especially in multihop wireless ad hoc networks. To improve the network throughput and diversity gain simultaneously, we investigate the issues and challenges in designing an efficient MAC scheme for such networks. Furthermore, based on the IEEE 802.11 DCF, a cross-layer designed cooperative MAC protocol is proposed. The MAC scheme adapts to the channel condition and payload length. [ABSTRACT FROM AUTHOR]

Recent studies demonstrated that dynamic spectrum access can improve spectrum utilization significantly by allowing secondary unlicensed users to dynamically share the spectrum that is not used by the primary licensed users. Cognitive radio was proposed to promote the spectrum utilization by opportunistically exploiting the existence of spectrum "holes." Meanwhile, cooperative relay technology is regarded widely as a key technology for increasing transmission diversity gain in various types of wireless networks, including cognitive radio networks. In this article, we first give a brief overview of the envisioned applications of: cooperative relay technology to CRNs, cooperative transmission of primary traffic by secondary users, cooperative transmission between secondary nodes to improve spatial diversity, and cooperative relay between secondary nodes to improve spectrum diversity. As the latter is a new direction, in this article we focus on this scenario and investigate a simple wireless network, where a spectrum-rich node is selected as the relay node to improve the performance between the source and the destination. With the introduction of cooperative relay, many unique problems should be considered, especially the issue for relay selection and spectrum allocation. To demonstrate the feasibility and performance of cooperative relay for cognitive radio, a new MAC protocol was proposed and implemented in a universal software radio peripheral-based testbed. Experimental results show that the throughput of the whole system is greatly increased by exploiting the benefit of cooperative relay. [ABSTRACT FROM AUTHOR]

As Ethernet traffic increases rapidly in carrier networks, service providers have an increasing need for Ethernet infrastructure networking in order to scale their Ethernet services. Ethernet infrastructure transports Ethernet traffic over distance, protects the traffic from link and nodal failures, and aggregates Ethernet connections from a large number of low-speed ports onto a much smaller number of high-speed ports. An Ethernet infrastructure allows service providers to inexpensively interconnect end user locations with one another for private line services, and to interconnect end users with the VPLS and IP/MPLS service edges for enterprise, residential, and mobility services. OAM and protection capabilities are critical to enable Ethernet to be deployed as an infrastructure technology. This article reviews several important developments in Ethernet OAM and protection standards, and discusses how those capabilities are vital for the creation of an effective Ethernet infrastructure. [ABSTRACT FROM AUTHOR]

In this article, a novel network architecture called resilient burst ring is proposed to implement the next-generation WDM-supported ultrahigh-speed (100 gigabit or higher) carrier Ethernet. This architecture inherits all the best features of resilient packet ring (IEEE 802.17), provides a burst-mode data transmission scheme through a two-sublayer (optical and electronic) hierarchy, and realizes the WDM-supported ultra-high-speed Ethernet with scalability and reliability. RBR adopts a two-layer buffering scheme to resolve the contentions of optical burst packets and provides three different data transmission modes. With the proposed PriorityOnly-Destination-Delay resource reservation control protocol, RBR can provide a flexible Q0S strategy to implement the transmission of all of the applications and services in existing networks. [ABSTRACT FROM AUTHOR]

In this article we study two representative mobility management schemes for mobile hotspots with heterogeneous multihop wireless links: the NEMO basic support protocol at the network layer and the SIP-based network mobility support protocol at the application layer. We evaluate their salient features and quantify their handoff latency. It is shown that the SIP-based network mobility support protocol can easily be deployed and reduce the tunneling overhead incurred in the NEMO basic support protocol. However, it increases handoff latency due to longer message length. We also discuss several open research issues for seamless mobility support in mobile hotspots. [ABSTRACT FROM AUTHOR]

The present view of medical environments, where isolated networks are used for IT and medical applications, is changing toward an integrated heterogeneous network scenario that can support a wide range of applications. WPAN and WLAN technologies will play a fundamental role in enabling such integrated environment that is expected to support both medical and nonmedical applications. The ultimate goal is to exploit WPAN and WLAN technologies, as well as other wireless networks, such as 3G cellular systems and satellite networks, to support highly efficient medical care delivery, anytime and anywhere. However, the life-critical nature of some medical applications imposes additional challenges that have not been considered in nonmedical scenarios. This article discusses some future scenarios where WLAN and WPAN technologies can be used to provide an integrated and ubiquitous network in medical environments, and identifies the main issues to be addressed in order to meet the QoS requirements of different medical applications when operating in integrated environment. [ABSTRACT FROM AUTHOR]

With the Information Age in full and rapid development, users are becoming accustomed to having immediate access to information. Users demand more capabilities from every kind of electronic device: more processing power, more features, and better connectivity. Users are also realizing the benefits of collaborating with others in their communities to help expand the body of knowledge. One user that understands the benefits of information sharing is the United States Department of Defense. The DoD's Network-Centric Enterprise Services initiative, along with the concept of pushing the ‘power to the edge,’ aims to enable end users with maximum situational awareness and the most comprehensive battlespace, all in a secure networking environment. Providing so much data and capabilities to the end user, however, will require an increase in communications capability and efficiency. To address increased capability needs, the DoD is continually developing and enhancing the Global Information Grid (GIG) throughout its various ‘layers’ of communication infrastructure. One such layer of infrastructure involves the use of cooperative low Earth orbiting satellites for efficient multicasting communications. In this article we review the network-centric concept and the GIG infrastructure. We then discuss the potential benefits to adding a low Earth orbit satellite communications infrastructure to the GIG model. Finally, we show how multicasting protocols can enhance the efficiency within the GIG and reduce some of the long-haul communications burdens. [ABSTRACT FROM AUTHOR]

This article reports the latest results of an R&D effort to develop a prototype implementation of a dynamic policy-based network management (PBNM) system that can be used to configure and manage a secure network for a coalition environment across an unsecured wide area network. The prototype, based on a distributed architecture, includes capabilities for policy creation and management, dynamic policy negotiation, and dynamic policy provisioning. The policy negotiation facilitates the rapid deployment of a coalition network while the dynamic policy provisioning automates the configuration and management of network services including firewalls, virtual private network connections, routing, quality of service (QoS), and domain name services. Such a PBNM system enhances an organization's ability to react to network incidents identified by a network situational awareness assessment. Although the focus of the current research is a military coalition environment, the system can be used in any distributed enterprise or collaborative environment. [ABSTRACT FROM AUTHOR]

This article presents a brief overview, state of the art, and taxonomy of optical WDM testbeds, and outlines the differences between them and the ADRENALINE testbed. ADRENALINE is an optical circuit-switched WDM testbed that deploys reconfigurable OADMs based on various technologies (e.g., AWO and tunable lasers). In ADRENALINE, end-to-end lightpaths are set up and torn down dynamically and in real time by means of a GMPLS-based control plane (switched connections) and a distributed management plane (soft-permanent connections). ADRENALINE supports the request of SPCs under user initiative by combining GMPLS, SNMP, and XML. ADRENALINE allows both the topology and major characteristics of the data communications network to be modified, enabling control and management related experiments with varying DCN. In our experiments we investigate user management of lightpaths and address its performance in terms of basic SLA parameters related to connection establishment (delay and availability). Finally, we address remaining challenges and outline exciting avenues of future work on ADRENALINE. [ABSTRACT FROM AUTHOR]

The emerging next-generation networking environment presents an IP-based core interconnecting many wireless radio access networks, providing ubiquitous access to end users through a vast variety of wireless devices. Although the IP protocol will be the common denominator, the new environment brings together many different interconnecting domains, each following different QoS models, complicating the overall end-to-end QoS process. This article discusses the need to standardize an end-to-end QoS protocol. It does not, however, focus on the signaling mechanism, since there is currently a relevant ongoing activity in IETF. Instead, it concentrates on the formulation of the QoS information describing the QoS requirements of the session to be established. It presents the Generic Service Specification Framework that not only enables the QoS requirements of a specific session to be captured (like a generic QoS template), but also the QoS classes of each IP domain can be described according to it. Through the systematic specification of a domain's QoS classes, an intelligent automatic mapping algorithm can be applied during an end-to-end QoS request, in order to select the most appropriate service class in each domain, as well as to extract the required traffic-related parameters to perform traffic con- trol operations, such as admission control, policing, and scheduling. [ABSTRACT FROM AUTHOR]