• 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.

• The KIPS Transactions:PartC
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• v.14C no.5
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• pp.425-430
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• 2007

Without the aid of stationary infrastructure, maintaining routing information for all nodes is inefficient in the Mobile Ad hoc Networks(MANET). It is more efficient when every time routing information is necessary that the source node broadcasts a query message to neighbour nodes. The source node using Ad hoc On-Demand distance Vector(AODV), which is one of the routing protocols of MANET, uses the Expanding Ring Search(ERS) algorithm which finds a destination node efficiently. In order to reduce the congestion of the network, ERS algorithm does not broadcast Route REQuest(RREQ) messages in the whole network. When the timer expires, if source node does not receive Route REPly(RREP) messages from the destination node, it gradually increases TTL value and broadcasts RREQ messages. Existing AODV cost a great deal to find a destination node because it uses a fixed NODE_TRAVERSAL_TIME value. Without the message which is added in existing AODV protocols, this paper measures delay time among the neighbours' nodes by making use of HELLO messages. We propose Adaptive ERS(AERS) algorithm that makes NET_TRAVERSAL_TIME optimum which apply to the measured delay time to NODE_TRAVERSAL_TIME. AERS suppresses the unnecessary messages, making NET_TRAVERSAL_TIME optimum in this paper. So we will be able to improve a network performance. We prove the effectiveness of the proposed method through simulation.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.668-671
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• 2010

최근 AODV 라우팅 프로토콜은 무선센서네트워크에서 노드 간에 데이터 전송방식을 추구하므로 테이블구동방식 중 가장 널리 사용되고 있다. AODV 라우팅 프로토콜은 목적지노드가 멀리 있거나 없는 경우엔 목적지노드를 찾기 위한 라우팅 패킷이 급격하게 증가하고 이로 인해 네트워크의 성능이 크게 저하된다. 이러한 문제점을 해결하기 위해 불필요한 RREQ 메시지를 제어하는 ERS(expanding ring search)방법을 사용한다. 그러나 ERS 방법은 유선 멀티캐스팅을 기본으로 하기 때문에 무선네트워크환경의 NTT(node traversal time)를 고려하지 않았다는 단점을 가지고 있다. 따라서 본 논문에서는 이동 무선 센서 노드들이 불규칙적으로 이동하는 무선센서네트워크에서 목적지 노드로부터 소스노드까지 전송되는 RREP의 소요시간, 노드간의 거리, 에너지량을 고려하여 효율적인 NTT 알고리즘을 제안한다.

• Journal of KIISE:Information Networking
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• v.35 no.6
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• pp.529-537
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• 2008

AODV routing protocol is intended for use by mobile' nodes in an ad-hoc network. In AODV nodes create routes on an on-demand basis. As the degree of node mobility becomes high, however, the number of the control packets, RREQ and RREP messages, have increased so rapidly. The unexpected increases in the number of the control packets cause the destination node to decrease the packet receiving rate and also to increase the overall energy consumption of such a network. In this paper, we propose a novel method of adaptively controlling the occurrences of such RREQ messages based on AIAD (additive increase additive decrease) under a consideration of the current network status. We have tested our proposed method with the conventional AODV and the method using timestamp based on the three performance metrics, i.e.. how long does node moves, node velocity, and node density, to compare their performance.