• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.3 no.1
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• pp.15-24
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• 2004

'The delay and control overhead during route discovery for destinations outside ad hoc networks are major obstacle to achieving scalability in the Internet. To solve this issue, we propose a novel route discovery scheme equipped with two augmented functions. In this paper, the Internet gateway maintains an address cache of Internet nodes frequently accessed from the ad hoc network and replies with an extended Route Response (RREP) message to the Route Request (RREQ) message based on its routing table and the address cache called EXIT(EXternal node Information Table). These augmented functions make the source node determine the location of the destination as fast as possible. Through simulations, the proposed route discovery scheme using both EXIT and extended RREP message shows considerable' reduction in both route discovery time and control message overhead.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.223-226
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• 2003

In this paper, we propose new agent discovery and route discovery schemes to support Mobile IP (MIP) in Ad Hoc networks with wireless backbone. The wireless backbone consisting of stationary wireless routers and Internet gateways (IGs) is a kind of wireless access network of IP-based core network. The proposed scheme utilizes favorable features of wireless backbone such as stable links and no energy constraints. In the agent discovery scheme, backbone-limited periodic Agent Advertisement (AA) and proxy-AA messages are used, which reduce network-wide broadcasting overhead caused by AA and Agent Solicitation messages and decentralize MIP processing overhead in IGs. In order to reduce delay time and control message overhead during route discovery far the destination outside Ad Hoc network, we propose a cache-based scheme which can be easily added to the conventional on-demand routing protocols. The proposed schemes can reduce control overhead during agent discovery and route discovery, and efficiently support MIP in Ad Hoc network with wireless backbone.

• Journal of Communications and Networks
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• v.6 no.4
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• pp.387-396
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• 2004

One of the main problems associated with MANETs is that mobility and the associated route discovery and maintenance procedures of reactive routing protocols cause severe interruptions on real-time video streams. Some of these interruptions are too large to be concealed using any sort of video technology, resulting in communications breaks unpleasant for the final end user. We present a solution for enhanced video transmission that increases route stability by using an improved route discovery process based on the DSR routing protocol, along with traffic splitting algorithms and a preventive route discovery mechanism. We also present some video adaptative mechanisms that improve the overall performance of multipath routing in terms of video data replication and video packet splitting strategies. Combining our proposals, we achieve up to 97% less interruptions on communication with high mobility and over 1.2 dB of improvements in terms of video distortion.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.154-156
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• 2006

These days wireless sensor networks receive much attention from industry and researchers on various fields. The challenge is that wireless sensor networks have limited resources. Nevertheless, the route discovery in ZigBee sensor networks is performed by simple flooding when the original racket is rebroadcasted at least once by every node in a network. Such uncontrolled flooding generates an excessive number of packets competing for the media and causes a high collision rate. In this article, we propose a suitable packet Time-To-Live value to solve problems of uncontrolled flooding in ZigBee networks. It is shown that more sufficient route discovery in a ZigBee network can save network resources and lengthen the life of a sensor network.

• Journal of information and communication convergence engineering
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• v.6 no.4
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• pp.396-404
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• 2008

Service discovery is the technology of finding needed services in networks, and a key point in pervasive computing environments. This paper presents a novel service discovery protocol: ASESDP(AIP and SRR Enhanced Service Discovery Protocol). In ASESDP, tow schemes are proposed to enhance its performance: AIP(Advertisement Information Piggybacked) and SRR(Shortest Reply Route). In AIP, parts of advertisement information are piggybacked in the service reply packet, which makes the advertisement information propagating along the reply path, and spreads its transmission area. In SRR, in order to reduce the service response time, the shortest reply route is chosen to forward the service reply packet to the source node sending the service request. With the theoretical analysis and Glomosim simulation results, it is verified that ASESDP can reduce the number of service request packets, save the response time, and improve the efficiency of service discovery.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.9
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• pp.920-926
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• 2007

Establishing a fixed path for the message delivery through a wireless network is impossible due to the mobility. Among the number of routing protocols that have been proposed for wireless ad-hoc networks, the AODV(Ad-hoc On-demand Distance Vector) algorithm is suitable in the case of highly dynamic topology changes, along with ZigBee Routing(ZBR), with the exception of route maintenance. Accordingly, this paper introduces a routing scheme focusing on the energy efficiency and route discovery time for wireless alarm systems using IEEE 802.15.4-based ZigBee. Essentially, the proposed routing algorithm utilizes a cluster structure and applies ZBR within a cluster and DSR (Dynamic Source Routing) between clusters. The proposed algorithm does not require a routing table for the cluster heads, as the inter-cluster routing is performed using DSR. The performance of the proposed algorithm is evaluated and compared with ZBR using an NS2 simulator. The results confirm that the proposed Cluster-based AODV (CAODV) algorithm is more efficient than ZBR in terms of the route discovery time and energy consumption.

• Journal of IKEEE
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• v.5 no.1 s.8
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• pp.59-66
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• 2001

In this paper, we propose a dynamic source routing protocol supporting asymmetric paths for mobile Ad Hoc networks that contain unidirectional links. At present, the existing dynamic source routing protocol supports only symmetric paths that consist of bidirectional links for routing. However, in fact, there can exist unidirectional links due to asymmetric property of mobile terminals or current wireless environment. Thus, we implement a mobile Ad Hoc routing protocol supporting unidirectional links, which is fit for more general wireless environment. Especially, the proposed protocol uses an improved multipath maintenance method in order to perform rapid route reconfiguration when route error due to mobility is detected. For performance evaluation, we consider the following factors: average route discovery time and average data reception rate. In order to obtain the factors of the performance evaluation, we did simulation for 900 seconds in the step of 100 seconds with the following scenarios: usage of route cache in intermediate nodes on route path, and different mobility/connection patterns.

• Journal of Korea Multimedia Society
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• v.16 no.8
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• pp.943-953
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• 2013

By the enormous increase in mobile nodes and diverse service requests on wireless networks, wireless mesh network(WMN) takes an interest as the solution for such requests. However, lots of issues which should be solved to deploy WMN are still remained. In the network layer, the performance improvement of routing protocols is the major issue of nowadays researches. WMN can be easily deployed by use of protocols for mobile ad-hoc networks(MANET) because it is much similar with MANET in multi-hop wireless routing and which node plays as host and router concurrently. Unfortunately, most routing protocols for MANET have drawbacks such as large traffic overhead and long delay time for route discovery due to the network extension. They are major factors of performance degradation of WMN and most researches are focused on them. In this paper, domain-based AODV which is amended AODV to be applied in hybrid WMN is proposed. The proposed scheme divides a hybrid WMN as several domains and performs route discovery by header layer domain. Therefore it can reduce the distance for route discovery as much as average hop count between domain header and member nodes. From the simulation, domain-based AODV was showed slowly increasing delay time due to the network extension.

• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.447-454
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• 2006

An ad-hoc network routing protocol, AODV(Ad-hoc On-demand Distance Vector) initially uses ERS(Expanding Ring Search) algorithm to control the RREQ(Route Request) retransmission in the route discovery process. Because ERS uses the fixed NTT(Node Travesal Time), it does not reflect accurately ad-hoc network environment. In this paper, we propose an improved ERS algorithm which lowers the retransmission rate. It uses RREP(Route Reply) and gives different weights in NTT of each node in accordance with the adjacency to an originating node. To show the effectiveness of the proposed algorithm, we perform a simulation using ns2. The simulation results showed that the proposed algorithm has better performance than existing algorithms.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1598-1601
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• 2002

Bluetooth technology of cable replacement and infrastructure access is verified enough to be commercialized as goods. But there are a lot of works to implement ad-hoc Bluetooth radio network. for this, scatternet must be formed. We propose routing layer, packet format and link formation schemes for scatternet. The page procedure of the route request and the route reply page eliminates the procedure of the inquiry and the master-slave role switching. The route discovery time could be lower than 50msec within the distance of 50m. Proposed link formation scheme lets master, slave and bridge establish connection automatically and offers active ad-hoc environment. Devices that adopt Bluetooth module of 10m transmission range can communicate with other devices far away without any intervention of users.