K. Al Agha

A link-state QoS routing protocol for ad hoc networks

A quality-of-service (QoS) routing protocol is developed for mobile ad hoc networks. We perform the proposed QoS-based routing in the optimized link state routing (OLSR) protocol, introducing a more appropriate metric than the hop distance. In our simulations the QoS routing protocol produces better performance comparing with the best-effort OLSR protocol.

QOLSR multi-path routing for mobile ad hoc networks based on multiple metrics: bandwidth and delay

Research on multi-path routing protocols to provide improved throughput and resilience in comparison with single-path routing has been explored in detail in the context of wired networks. However, the multi-path routing mechanism has not been explored thoroughly in the domain of ad hoc networks. We propose the path selection criteria and QOLSR multi-path calculation based on bandwidth and delay. QOLSR is an extension to the single-path routing protocol known as the optimized link state routing (OLSR) protocol; it uses bandwidth and delay to satisfy end-to-end QoS requirements. The resulting protocol computes multiple loop-free and node-disjoint paths. The loop-free property is guaranteed by using the shortest-widest path algorithm. The node-disjoint property of multiple paths is achieved using our proposed algorithm. We also present an evaluation comparison of QOLSR multi-path routing against QOLSR single-path routing using a scalable simulation model.

QoS routing in ad hoc networks using QOLSR with no need of explicit reservation

Multimedia applications often require guaranteed quality of service (QoS) and resource reservation, which has raised a number of challenging technical issues for routing. We have proposed the QOLSR protocol, a QoS routing over OLSR protocol introducing metrics, such as bandwidth and delay, that are more appropriate than the hop distance. When using the QOLSR protocol, there are cases in which a source node continuously changes a flows next hop in response to the change of available bandwidth on its path and cannot tell apart the traffic induced by itself from traffic generated by other nodes. The article describes a way to achieve QoS routing without using explicit reservation mechanisms and gives new distributed solutions to the oscillation and collision of flows. We can guarantee that the flows take the appropriate paths and avoid interferences with other existing flows. The performance of our distributed algorithm is extensively investigated by analyses, examples and simulations in both static and dynamic networks. Our results show that the gain achieved by our proposal represents an important improvement in mobile wireless ad hoc networks.

An efficient QOLSR extension protocol for QoS in ad hoc networks

Quality of service (QoS) support in mobile ad hoc networks (MANETs) is a challenging task. We have developed the QOLSR protocol, a QoS routing over OLSR (optimized link state routing) protocol introducing more appropriate metrics than the hop distance, such as bandwidth and delay. The paper discusses a proposed extension to the QOLSR protocol to provide integrated services, i.e., to support real-time as well as the current non-real-time service of IP. This extension is necessary to meet the growing need for real-time service for a variety of new applications, including teleconferencing, remote seminars. telescience, and distributed simulation. We include the various QoS parameters in the IPv6 flow label. The performance of our extension is extensively investigated by simulation. Our results indicate that the gain attained by our proposal represents an important improvement in such mobile wireless networks.

Fast and efficient vertical handoffs in wireless overlay networks

Mobile IP is used to keep track of location information and make the data available to the mobile device anytime, anywhere. It designed to address the macromobility management problem, it does not address microlevel mobility issues such as handoff latency and packet loss. In this paper, we propose a fast and efficient handoff scheme to handle the movements of mobile nodes among a different wireless network technologies. Our scheme combines: (a) A hierarchical mobility management architecture to hide mobility of mobile nodes within the foreign domain from the home agent, (b) The use of multicast as the packet forwarding mechanism from the getaway foreign agent to the base stations, (c) The use of our proposed virtual cells in order to reduce the upward vertical handoff latency and disruption as much as possible. Our design is based on the Internet protocol (IP) and is compatible with the mobile IP standard (MIP). We also present simulation results showing that our handoff scheme is very fast and avoid packet loss.

Virtual time synchronization for multimedia ad hoc networks

We propose a novel protocol to deal with the synchronization problem of multimedia ad hoc networks. Our proposal eliminates the need for hard clock synchronization by implementing a virtual scheme that relies on the desynchronization between nodes. Such a decision is made because of the dynamic nature of the network topology. Therefore, the proposed algorithm computes the clock offsets between a node and each one of its one hop neighbors. We formulate our algorithm by deriving simple expressions combining stochastic and measured parameters. The proposed algorithm is validated through implementation and the results show that high levels of synchronization are achieved.

Resource allocation based on handoff prediction in WCDMA

Resource allocation in wireless cellular systems depends on the multiple access technique used (TDMA, CDMA) and varies upon traffic distribution in the cellular environment. In CDMA systems, all users that monitor several strong carriers should apply a soft handoff procedure. Typically, these users are located in cell overlapping regions. In a soft handoff state, a user is connected simultaneously to more than one cell and consequently uses more resources. On the other hand, studies show that a users movements in a cellular network can be predictable. We apply a resource allocation strategy based on handoff prediction by using mobile agents. A mobile agents-based framework is used to enable handoff prediction and provides parameters to the applied resource allocation scheme. By simulation, we compute the gain obtained in terms of call blocking and handoff failures.

Channel segregation for slot assignment in integrated voice and data systems

An integrated voice and data system using the channel segregation protocol (CS) is analyzed. To achieve each service target carrier to interference ratio (C/I), and meet the associated bit error rate (BER) requirements, the learning process inherent in the CS is extended by weighting the slot priorities, based on previous successful attempts, according to each service C/I requirement. Simulation results show an improvement in call block and achieved C/I levels for voice while the average delays for packet data are improved as well. The study is conducted for non real time packet data services exhibiting heavy tailed packet size distributions.

An ad hoc networking for inter-MONET using mobile IPv6 and OLSR

Trends in 4G wireless networks are clearly identified by the full-IP concept where all traffic (data, control, voice and video services. etc.) are transported in IP packets. The mobile network (MONET) is a group of mobile nodes moving together as a unit. Such groups are common characteristics of the vehicular environments, for example train and buses (which are attractive because of the high concentration of passengers on these vehicles). This paper investigates an ad hoc networking for inter-MONET communications and interworking between MONETs and the global Internet. We propose a hierarchical architecture: (1) integrating mobile IPv6 and OLSR, a routing protocol for ad hoc networks, to manage universal mobility and to avoid the nested problem; and (2) connecting this ad hoc network to the Internet. The heterogeneous communication is established with the help of specific access routers, which serve as gateways. We describe the network scenario, its basic protocol architecture and we discuss the different practical approaches for routing. We validate our proposed architecture by analyses and simulations.

OSSC: a new scheme for code allocation in WCDMA

Future wireless systems will have to support multimedia services such as voice, video and data. Several mechanisms, like multiple access, bandwidth allocation and power control are used for providing these multimedia services. In the 3/sup rd/ generation of wireless systems, WCDMA is used for the access method in the FDD mode. Therefore, the capacity of the system is based on the cross correlation among the users allocated scrambling codes. In this work, we analyze the WCDMA uplink resource allocation and propose a new method, called one service-one scrambling code (OSSC), that reduces the aggregate number of scrambling codes assigned to users in a cell. We also study the impact of the scrambling code assignment on the call interference and the system capacity. An analytical model is provided in this paper.