Taek Jin Kwon

Clustering with power control

This paper proposes a stable, dynamic, distributed clustering for energy efficient networking. Via simulation, we evaluate the impacts of mobility and transmission power variation on network stability.

A survey and challenges in routing and data dissemination in vehicular ad hoc networks

In this paper, we survey recent results in VANET data dissemination. We structure the survey into three broad categories: geocast/broadcast, multicast, and unicast approaches; and describe key ideas of representative technologies in each category. In addition, we consider location service and security issues that are crucial for data dissemination in VANET. We conclude by sharing our thoughts on further challenges.

A Mobility Framework for Ad Hoc Wireless Networks

Mobility management in ad hoc wireless networks faces many challenges. Mobility constantly causes the network topology to change. In order to keep accurate routes, the routing protocols must dynamically readjust to such changes. Thus, routing update traffic overhead is significantly high. Different mobility patterns have in general different impact on a specific network protocol or application. Consequently the network performance will be strongly influenced by the nature of the mobility pattern. In the past, mobility models were rather casually used to evaluate network performance under different routing protocols. Here, we propose a universal mobility framework, Mobility Vector Model, which can be used for recreating the various mobility patterns produced in different applications. Case studies on optimal transmission range as a function of mobility and on network performance under various mobility models are presented in the paper. Simulation results show that excessively large transmission range will not improve network performance significantly because of the increased collisions. There is an optimal range between 1.5 - 2 times the mean node distance for free space channel. Also, simulation results show that different mobility models will have different impact on the network performance for a variety of routing protocols (AODV, DSR, FSR). When choosing routing protocols for ad hoc network applications, performance studies under multiple mobility models are recommended. The Mobility Vector model can provide a realistic and flexible framework for reproducing various models.

Architectures and Protocols for Capacity Efficient, Highly Dynamic and Highly Resilient Core Networks [Invited]

The Core Optical Networks (CORONET) program addresses the development of architectures, protocols, and network control and management to support the future advanced requirements of both commercial and government networks, with a focus on highly dynamic and highly resilient multi-terabit core networks. CORONET encompasses a global network supporting a combination of IP and wavelength services. Satisfying the aggressive requirements of the program required a comprehensive approach addressing connection setup, restoration, quality of service, network design, and nodal architecture. This paper addresses the major innovations developed in Phase 1 of the program by the team led by Telcordia and AT&T. The ultimate goal is to transfer the technology to commercial and government networks for deployment in the next few years.

A survey and challenges in routing and data dissemination in vehicular ad-hoc networks

In this paper, we survey recent results in VANET data dissemination. We structure the survey into three broad categories: geocast/broadcast, multicast, and unicast approaches; and describe key ideas of representative technologies in each category. In addition, we consider location service and security issues that are crucial for data dissemination in VANET. We conclude by sharing our thoughts on further challenges.

A load aWare routing (LWR) based on local information

This paper suggests a new load aware routing (LWR) enhancement that improves on-demand routing protocols significantly in ad hoc networks. This paper describes deterministic characteristics of ad hoc networks and suggests improved routing strategies that can sustain the network functionality even under highly stressful data traffic. LWR evenly distributes the load throughout the networks. It also reduces redundant packet flooding which is major limitation of conventional ad hoc routing algorithms. Simulation results illustrate the performance improvements obtained with LRW by using new flooding control over conventional on-demand routings.

Towards commercialization of ad hoc networks

Ad hoc networks have seen useful applications in military environments. However, partly due to the lack of research in the area, and because of characteristics of existing ad hoc routing protocols, commercial fields of application for ad hoc networks are hard to find. We focus on specific fields of application and assess the viability of using ad hoc networks in those fields. We examine in particular the emergency fire-fighting scenario and present some simulation results using simulated movement traces of fire fighters in typical fire-fighting tasks.

The selective intermediate nodes scheme for ad hoc on-demand routing protocols

The on-demand routing schemes in mobile ad hoc networks are appealing because of the lower routing overhead, compared with traditional proactive schemes. The on-demand routing protocols introduce routing overhead only in the presence of data packets that need routes. However, the control overhead of on-demand routing schemes increases with node geographic density and traffic pattern density. In fact, this is an undesirable feature for the scalable routing protocols whose control overhead should be under control to keep up with increasing offered load. As a solution for such a drawback of current reactive routing schemes, we propose the selective intermediate nodes mechanism. In this protocol, each node adaptively propagates routing information based on the local load level and cluster status. The local load level (local load status), based on channel utilization and queue size, reflects the load of the node in question and of all of its neighbors; the cluster status denotes the role of a node in a cluster (i.e., a cluster head, gateway or ordinary node). We demonstrate the effectiveness of our enhancement by applying it to ad hoc on-demand distance vector routing (AODV) and dynamic source routing (DSR). Simulation results show that the proposed idea significantly reduces the control overhead and improves the overall performance and scalability of the routing protocols.

Unicast Routing among Local Peer Group (LPG)-Based VANETs

In recent years, there have been significant efforts related to vehicle-to-vehicle (V2V) communication. The major demand of the V2V communication was originally from safety-related applications; and the possible application areas including communication support for auto-navigation have increased. Local Peer Group (LPG) is a partitioning structure to promote quick deliveries of time- sensitive information and efficient use of wireless media. LPG organizes vehicles into manageable vehicle groups prior to a need for delivering relevant emergency messages, and provides efficient data dissemination (both multicast and unicast) among vehicles. In this paper, we first provide an overview of LPG structure and proactive unicast inside LPG. As the focus of this paper, we then present a new on-demand unicast routing protocol that supports inter-LPG communications - with aspects of route search, establishment and maintenance. Our preliminary simulation results indicate that our proposed inter-LPG unicast routing protocol has control overhead that is significantly lower than the conventional on-demand routing protocols.

DiffServ QoS and OLSR MANET Outdoor Demonstration

The CECOM MOSAIC ATD encompasses an integrated set of diverse technologies to demonstrate rapidly deployable, secure, robust, assured-QoS communications among mobile ad hoc nodes. The assured IP QoS technology solution integrates DiffServ based QoS resource management with centralized admission control over a dynamic tactical network environment. We describe an outdoor demonstration of our QoS technology prototype over an on-the-move MANET running OLSR. This demonstration does not include IP mobility support, however provides an alternate route between the ad hoc nodes through the use of two distinct wireless networks. The demonstration exhibits route changes between single and multiple IP hops as the nodes drive, and shows handoff between wireless networks as they move out of range of one radio network to the other. We summarize our observations and empirical performance results for real-time traffic