Mahmoud Naghshineh

Equivalent capacity and its application to bandwidth allocation in high-speed networks

The authors propose a computationally simple approximate expression for the equivalent capacity or bandwidth requirement of both individual and multiplexed connections, based on their statistical characteristics and the desired grade-of-service (GOS). The purpose of such an expression is to provide a unified metric to represent the effective bandwidth used by connections and the corresponding effective load of network links. These link metrics can then be used for efficient bandwidth management, routing, and call control procedures aimed at optimizing network usage. While the methodology proposed can provide an exact approach to the computation of the equivalent capacity, the associated complexity makes it infeasible for real-time network traffic control applications. Hence, an approximation is required. The validity of the approximation developed is verified by comparison to both exact computations and simulation results. >

Channel assignment schemes for cellular mobile telecommunication systems: a comprehensive survey

This article provides a detailed discussion of wireless resource and channel allocation schemes. The authors provide a survey of a large number of published papers in the area of fixed, dynamic, and hybrid allocation schemes and compare their trade-offs in terms of complexity and performance. We also investigate these channel allocation schemes based on other factors such as distributed⁄centralized control and adaptability to traffic conditions. Moreover, we provide a detailed discussion on reuse partitioning schemes, the effect of handoffs, and prioritization schemes. Finally, we discuss other important issues in resource allocation such as overlay cells, frequency planning, and power control.

An architecture and methodology for mobile-executed handoff in cellular ATM networks

An architecture is presented for a high-speed cellular radio access network based on ATM transport technology. Central to this approach is a new concept known as the virtual connection tree which avoids the need to involve the network call processor for every cell handoff attempt. Such an approach can readily support a very high rate of handoffs, thereby enabling use of physically small radio cells to provide very high system capacity, but may occasionally cause the volume of traffic to be handled by one cell site to exceed that cell sites capacity. A simple analytical methodology is developed which can be used for admission control, the purpose of which is to limit the number of in-progress calls such that two new quality of service metrics (overload probability and average time in overload) can be kept suitably low. Finally, a general framework is presented for overall system organization and signaling. >

Bluetooth: vision, goals, and architecture

A few years ago it was recognized that the vision of a truly low-cost, low-power radio-based cable replacement was feasible. Such a ubiquitous link would provide the basis for portable devices to communicate together in an ad hoc fashion by creating personal area networks which have similar advantages to their office environment counterpart - the local area network (LAN). Bluetooth is an effort by a consortium of companies to design a royalty free technology specification enabling this vision. This article describes the vision and goals of the Bluetooth program and introduces the radio-based technology.

WebSplitter: a unified XML framework for multi-device collaborative Web browsing

WebSplitter symbolizes the union of pervasive multi-device computing and collaborative multi-user computing. WebSplitter provides a unified XML framework that enables multi-device and multi-user Web browsing. WebSplitter splits a requested Web page and delivers the appropriate partial view of each page to each user, or more accurately to each users set of devices. Multiple users can participate in the same browsing session, as in traditional conferencing groupware. Depending on the access privileges of the user to the different components of content on each page, WebSplitter generates a personalized partial view. WebSplitter further splits the partial view among the devices available to each user, e.g. laptop, wireless PDA, projection display, stereo speakers, orchestrating a composite presentation across the devices. A wireless PDA can browse while remotely controlling the multimedia capabilities of nearby devices. The architecture consists of an XML metadata policy file defining access privileges to XML tags on a Web page, a middleware proxy that splits XML Web content to create partial views, and a client-side component, e.g. applet, enabling user login and reception of pushed browsing data. Service discovery finds and registers proxies, browsing sessions, and device capabilities. We demonstrate the feasibility of splitting the different tags in an XML Web page to different end users browsers, and of pushing updates from the browsing session to heterogeneous devices, including a laptop and a PDA.

Control and quality-of-service provisioning in high-speed microcellular networks

esign and implementation of broadband networks is one of the major focal areas in modern telecommunications. With recent developments in the field of wireless, hand-held terminals, as well as in personal communications services (PCS) [l-61, integration of mobile, wireless connections in a backbone broadband network is an essential and challenging task since mobile users may need to access the communication services offered by the fixed broadband network. This implies that wireless networks must provide packetbased t ransport and bandwidth-upon-demand, as well as support multimedia applications. Since the radio spectrum is limited, future wireless systems will have micro/picocellular architectures in order to provide the higher capacity needed to support broadband services [7-91. Due to the small coverage area of micro/picocells and characteristics of the multipath and shadow fading radio environment, hand-off events in future microcellular systemswill occur at a much higher rate as compared to today’s macrocellular systems, and control of such systems will introduce a new set of challenges. We canviewwirelessimobile connections as consisting of paths (or routes) through the broadband backbone network; and radio links between the mobile, wireless terminals and base stations (or access points) which are the interface of mobile users to the fixed backbone network. When the quality of a radio link between a wireless terminal and its access point degrades, a new access point with acceptable quality must be found (hand-off), and network control functions of both the fixed and wireless network need to be invoked. In the backbone network, hand-off requires the establishment of a new route, which transports the packets destined to (or originated from) the wireless terminal to (or from) the new access point. Here, network call processing functions need to be invoked in order to set up such a route and ensure that the newly established route maintains acceptable quality-of-service (QOS) to both the wireless connection and to pre-existing calls sharing links of the new route. Furthermore, to execute hand-off, the network call controller must first ensure that the new wireless connection does not overload the new access point and then create a radio link between the mobile terminal and the new access point. As one can see, a substantial number of call processing and control functions of the fixed and wireless network must be invoked to complete a hand-off event. If such control functions are performed in a centralized fashion, call processing of handoff events would impose a bottleneck on the capacity of future microcellular networks. In this article, we propose and study distributed control methodologies for high-speed microcellular networks based on a hierarchical grouping of backbone and wireless network resources. With our approach, a number of adjacent cells are grouped into a cell-cluster that is used for call setup and control of the radio links, and all access points in a cell-cluster belong to the same backbone network connection tree, to be used for call setup and control of the backbone portion of wireless connections.

PARO: supporting dynamic power controlled routing in wireless ad hoc networks

This paper introduces PARO, a dynamic power controlled routing scheme that helps to minimize the transmission power needed to forward packets between wireless devices in ad hoc networks. Using PARO, one or more intermediate nodes called “redirectors” elects to forward packets on behalf of source–destination pairs thus reducing the aggregate transmission power consumed by wireless devices. PARO is applicable to a number of networking environments including wireless sensor networks, home networks and mobile ad hoc networks. In this paper, we present the detailed design of PARO and evaluate the protocol using simulation and experimentation. We show through simulation that PARO is capable of outperforming traditional broadcast-based routing protocols (e.g., MANET routing protocols) due to its energy conserving point-to-point on-demand design. We discuss our experiences from an implementation of the protocol in an experimental wireless testbed using off-the-shelf radio technology. We also evaluate the impact of dynamic power controlled routing on traditional network performance metrics such as end-to-end delay and throughput.

Balanced media access methods for wireless networks

Fairness algorithms and access methods enable non-zero channel access for wireless communication systems operating in a random access channel environment. Fair access to a random access channel for each station in a wireless network is assured by each station calculating a priority or probability for accessing the channel based on logical connections among certain stations, based on other stations perception of the channel and based on each calculating stations own perception of the channel properties.

QoS provisioning in wireless/mobile multimedia networks using an adaptive framework

Recently there is a growing interest in the adaptive multimedia networking where the bandwidth of an ongoing multimedia call can be dynamically adjusted. In the wireless/mobile multimedia networks using the adaptive framework, the existing QoS provisioning focused on the call blocking probability and the forced termination probability should be modified. We, therefore, redefine a QoS parameter – the cell overload probability – from the viewpoint of the adaptive multimedia networking. Then, we propose a distributed call admission control (CAC) algorithm that guarantees the upper bound of the cell overload probability. Also, a bandwidth adaptation algorithm which seeks to minimize the cell overload probability is also presented. Simulation experiments are carried out to verify the performance of the proposed CAC algorithm. Furthermore, the performance of the adaptive wireless/mobile network is compared to that of the existing non-adaptive wireless/mobile networks. As a further step in QoS provisioning, we propose another QoS parameter, the degradation period ratio, and discuss analytically how the CAC algorithm guarantees the upper bound of the degradation period ratio.

QoS provisioning in micro-cellular networks supporting multiple classes of traffic

We introduce an adaptive call admission control mechanism for wireless/mobile networks supporting multiple classes of traffic, and discuss a number of resource sharing schemes which can be used to allocate wireless bandwidth to different classes of traffic. The adaptive call admission control reacts to changing new call arrival rates, and the resource sharing mechanism reacts to rapidly changing traffic conditions in every radio cell due to mobility of mobile users. In addition, we have provided an analytical methodology which shows that the combination of the call admission control and the resource sharing schemes guarantees a predefined quality-of-service to each class of traffic. One major advantage of our approach is that it can be performed in a distributed fashion removing any bottlenecks that might arise due to frequent invocation of network call control functions.