Minseok Oh

Performance of Expanding Ring Search Scheme in AODV Routing Algorithm

AODV (ad hoc on-demand distance vector) routing protocol provides communication between mobile nodes with minimal control overhead and minimal route acquisition latency. It is well-known as a reactive routing protocol along with OLSR (optimized link state routing). Its goal is to reduce the need for system-wide broadcasts to the furthest extent possible. To control network-wide broadcasts of RREQs, the source node uses an expanding ring search technique, which allows a search of increasingly larger areas of the network if a route to the destination is not found. In this paper, we investigate the effectiveness of this ring search scheme by comparing the number of routing messages during routing discovery procedure.

An Adaptive Routing Algorithm for Wireless Mesh Networks

Ad hoc networks can be very mobile, where mobile nodes (MNs) are moving frequently relative to one another. The faster the MNs are moving, the more the routing information is required to keep each MNs informed of the route information to other MNs. This paper proposes a hybrid routing algorithm, whose behavior is modified dynamically based on MNs mobility in the network. This would allow using proactive algorithms when a network has low mobility, and allow using reactive algorithms when a network becomes very mobile. In this paper, destination sequenced distance vector (DSDV) is used as a proactive routing algorithm and ad hoc on-demand vector (AODV) is used as a reactive algorithm.

A Workflow Fragmentation Framework for Enterprise Grid Workflow Systems

In this paper, we focus on a workflow distribution methodology for deploying the workflow enactment functionality over enterprise grid computing environments. The essential idea of the workflow distribution methodology is about how to fragment a workflow model and how to allocate the fragmented workflow models over the workflow enactment infrastructure based upon an enterprise grid computing environment. The workflow distribution methodology, as an impeccable solution to implement the essential idea, proposed in the paper is a workflow fragmentation framework, which is broken down into three fragmentating approaches vertical workflow fragmentation approach, horizontal workflow fragmentation approach and hybrid of both. Conceptually speaking, the typical vertical fragmentation approach implies semantic-driven fragmentation methods, while on the other the horizontal fragmentation approach is to represent syntactic-driven fragmentation methods. Based on the ICN-based structured workflow model, this paper formalizes the proposed approaches of the workflow fragmentation framework and their detailed algorithms, and applies one of the approaches to an ICN-based structured workflow model as an operational example.

A hybrid routing protocol for wireless Mesh Networks

Wireless ad hoc networks can be very mobile, where mobile nodes (MNs) are moving frequently relative to one another. The faster the MNs are moving, the more the routing information is required to keep each MNs informed of the route information to other MNs. This paper proposes another hybrid routing algorithm, whose behavior is modified dynamically based on MNs mobility in the network following a prior work flj. This would allow using proactive algorithms when a network has low mobility, and allow using reactive algorithms when a network becomes very mobile. In this paper, Destination Sequenced Distance Vector (DSDV) is used as a proactive routing algorithm and Dynamic Source Routing (DSR) is used as a reactive algorithm.

Multipoint conference systems in a ubiquitous environment

In a ubiquitous environment, people can communicate with others and have access to various computing services any time, any place. The multipoint conference systems in a ubiquitous environment are expected to be one of the leading applications to connect people. In this paper the various multipoint conference systems are compared for their efficiency in a ubiquitous environment and shows why the endpoint mixing conference scheme performs effectively in an ad hoc environment. However, the endpoint mixing conference scheme has its own drawbacks as well and we propose solutions for them.

An Experimental Comparison of Packet Delivery Schemes in a Linear Mesh Topology

In this paper, we compare and analyze the performances of two mesh routing protocols (BATMAN-ADV and FLAME) and a WDS implementation of the IEEE 802.11, all of which run on Layer 2 of the OSI reference model. Sometimes the mesh network may simply form a linear topology to provide a service coverage to a line-shaped area. A linear topology can be built without any routing protocol involved, using WDS. The first two routing protocols are a few protocols available in software package incorporated into the OpenWrt OS for embedded systems. Our experiments involves the throughput and delay performance measured on a linear mesh network over varying number of hops between two end nodes. We have used 5.8GHz channel bands to avoid any interference with existing 802.11g radios. The results show that WDS performs best in throughput and round trip time delay. The higher throughput and the lower delay of WDS is attributed to the structural efficiency of the WDS delivery mechanism.

A Multipath AODV in Wireless Networks

This paper proposes a multipath AODV routing protocol, where the routing information is obtained from the multiple paths which the routing messages go through. The AODV (Ad-hoc On-demand Distance Vector) routing algorithm is one of the most widely used routing protocols in wireless ad-hoc networks which are composed of mobile nodes. We improve the AODV routing algorithm by investigating the weakness of it and modifying the existing AODV. AODV, which obtains the routing information by the route discovery procedure, a node may not have all the routing information. So when it needs to send packets, it may have to initiate the route discovery procedure and delay the delivery of the packets. The proposed routing protocol increases the reliability in routing packets by using multiple paths from a source to a destination. It performs well in a small-size wireless ad-hoc network and reduces the number of control messages when a link is broken.

Performance of a Forwarding Layer for Mesh Network

In this paper, we introduce our experience with implementation of an ad hoc network. The routing algorithm uses in-band traffic to distribute the routing information instead of providing a separate routing protocol. A 4 hop straight line topology ad hoc network is established for measuring the throughput in terms of hops. The experimental results show that the throughput reduces exponentially approximately by 60% for every hop increment. The delay seems to increase linearly for every hop increment. We have also compared the throughput and delay when the routing protocol is applied with those when it is not, to see how much the routing protocol affects the performance for one hop link connection. We have found that the routing protocol indeed consumes network resources such that the throughput reduces by 6.45% and the delay by 95.8%. The cause of the performance degradation for this specific routing protocol has been analyzed.