• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.11B
• /
• pp.1676-1684
• /
• 2010

Tactical network environments are characterized by unreliable connectivity, communication links which has limited bandwidth compared to commercial networks and distributed architecture where users have high mobility. The best route should be selected based on the required traffic characteristics which can be a wireless channel environments and a status of nodes which are moving. Those characteristics are self aware and should be a routing decision factor in order to guarantee a reliable data transfer. In this paper we define the requirements of services and traffic characteristics on tactical network environments and suggest the new routing method "AODV-IMTC" based on selective routing metric to enable efficient data transfer in wireless ad hoc networks.

• Proceedings of the KAIS Fall Conference
• /
• 2009.12a
• /
• pp.994-997
• /
• 2009

MANET은 노드가 이동성을 가지고 있으며, 네트워크 위상을 자율적으로 결정하는 특성을 가지고 있다. 정책기반 망 관리 시스템을 MANET에 도입하기 위한 연구는 이러한 네트워크 특성을 고려하여 신뢰성과 효율성을 확보하기 위해 이루어지고 있다. 또한, 정책기반 망 관리 시스템은 유선 네트워크를 기반으로 제안되어 있으므로 이를 MANET에 도입하기 위해서는 여러 가지 수정이 필요한 부분이 있다. 정책 기반 망 관리 시스템은 SNMP의 MIB나 LDAP를 이용하는 정책 저장소와 노드의 상태를 수신하여 정책을 배포하는 정책결정자, 그리고 정책을 수신하여 수행하는 정책 수행자 노드가 있다. 본 논문에서는 MANET 라우팅을 이용하고 표준 정책 기반 망 관리 시스템에서 정책 결정자와 정책수행자 사이의 프로토콜로 제안된 COPS-PR을 MANET에 특성에 맞게 수정한 능동적 PDP 탐색 메커니즘을 이용한 테스트베드를 설계하고 구현한다.

• The KIPS Transactions:PartC
• /
• v.17C no.3
• /
• pp.259-270
• /
• 2010

In this paper, a Location Information-based Gradient Routing (LIGR) algorithm is proposed for setting up routing path based on physical location information of sensor nodes in wireless ad-hoc networks. LIGR algorithm reduces the unnecessary data transmission time, route search time, and propagation delay time of packet by determining the transmission direction and search range through the gradient from the source node to sink node using the physical location information. In addition, the low battery nodes are supposed to have the second or third priority in case of forwarding node selection, which reduces the possibility of selecting the low battery nodes. As a result, the low battery node functions as host node rather than router in the wireless sensor networks. The LIGR protocol performed better than the Logical Grid Routing (LGR) protocol in the average receiving rate, delay time, the average residual energy, and the network processing ratio.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.8
• /
• pp.942-949
• /
• 2016

Efficient routing protocols designed for Wireless Sensor Networks (WSN) can be extended and applied to Internet of Things (IoT) data routing, as IoT can be considered to be an extension from WSN. When the size of the data in IoT is often bigger than in conventional WSNs, existing cluster routing protocol such as LEACH may cause high data loss rate due to its incomplete load balancing. We present an enhanced LEACH-based protocol which can minimize the data loss which is an important performance measure in IoT. In our proposed protocol, the base station estimates the location of nodes by the trilateration technique to make sure optimal number of cluster heads and members in a deterministic manner. We evaluate our proposed protocol via computer simulations in terms of data loss rate and average network lifetime.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.4A
• /
• pp.369-379
• /
• 2011

During the routing process between nodes on the CR(Cognitive Radio) network conducting for efficient use of limited frequency resources, spectrum handover process due to the appearance of the PU occupies most of the routing latency, and also decreases the reliability of the path. In this paper, a cooperative routing protocol in a multi-channel environment is proposed. The source node broadcasts a message with available channel lists and probability of PU appearance during its route guidance. The intermediate nodes re-transmit the message, received from the source node, and update and maintain the information, status table of the path. The destination node determines the optimal path and sends a reply message to the selected path after it receives the messages from the intermediate nodes. The average probability of the PU appearance and the average time of the PU appearance are updated while transferring data. During data transmission the channel with the lowest probability of appearance of the PU is selected dynamically and if a PU appears on the current channel partial repairment is performed. It is examined that reliability of the selected path considerably is improved and the routing cost is reduced significantly compared to traditional routing methods.

• Journal of KIISE:Computer Systems and Theory
• /
• v.30 no.5_6
• /
• pp.280-289
• /
• 2003

Deadlock recovery-based routing algorithms in wormhole networks have gained attraction due to low hardware complexity and high routing adaptability Progressive deadlock recovery techniques require a few dedicated resources to transmit deadlocked packets rather than killing them. Selection of deadlocked packets is primarily based on time-out value which should be carefully determined considering various traffic patterns or packet length. By its nature, current techniques using time-out accompany unignorable number of false deadlock detections especially in a heavy-loaded network or with long packet size. Moreover, when a deadlock occurs, more than one packet may be marked as deadlocked, which saturate the resources allocated for recovery. This paper proposes more accurate deadlock detection scheme which does not make use of time-out to declare deadlock. The proposed scheme reduces the probability to detect false deadlocks considerably. Furthermore, a single message is selected as deadlocked for each cycle of blocked messages, thereby eliminating recovery overheads.

• Journal of KIISE:Information Networking
• /
• v.31 no.6
• /
• pp.673-684
• /
• 2004

As the wireless mobile communication is being widespread, mobile technologies will have important roles in the communication with the explosive growth of demanding for wireless portable devices. Among the mobile technologies, a great deal of interest has been taken in mobile ad hoc network (MANET), which is a collection of wireless mobile nodes forming a temporary network without the aid of stationary infrastructure in recent. Furthermore, considering characteristic of ad hoc networks, the design of efficient routing protocols is an important issue. In recent years, on-demand protocols among routing protocols have noticed because of the low routing overhead. However, on-demand protocols suffer from production of the enormous query Packets by broadcasting in order to setup routes, that is, a flooding scheme. The flooding scheme is very costly and results in serious problem, which we refer as the broadcast storm problem. In this paper, we propose a Dynamic Adaptation Query flooding Using Neighbor Topology (NT-DAQ) scheme, in order to resolve the broadcast storm Problem. When a route discovery is in progress, each mobile node decides on the basis of neighbor topology information whether discovery process participates or not. Therefore, our proposed scheme enables to improve network performance in which minimize the number of query rackets. We evaluate the efficiency of our proposed scheme through simulation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2009.06a
• /
• pp.179-180
• /
• 2009

자동화 컨테이너 터미널의 생산성을 향상시키기 위해서는 안벽크레인의 작업 지연 시간을 최소화하는 것이 중요하다. 안벽크레인의 작업 지연 시간은 이송 차량들이 효율적으로 주행하여 제 시간에 필요한 위치에 컨테이너를 운반함으로써 단축이 가능하다. 이송차량의 주행 경로는 사전에 결정된 레이아웃에서 최단 거리, 최단 시간 경로 등의 라우팅 방법을 통해 결정된다. 주행 경로 레이아웃은 안벽크레인의 작업이 진행됨에 따라 안벽 크레인의 위치, 작업 물량 및 병목지점이 변화하므로 동적으로 조정한 필요가 있다. 본 논문에서는 안벽 크레인의 위치 변화에 따라 주행 경로 레이아웃을 동적으로 최적화하는 방안을 제안한다. 제안방안의 효율성은 시뮬레이션 실험을 통해 검증하였다.

• Proceedings of the KAIS Fall Conference
• /
• 2004.11a
• /
• pp.214-217
• /
• 2004

본 논문은 제안된 스위치가 하드웨어로 구현된 ATM 셀의 출력포트에 따라 ATM 셀을 정렬하는 프로시져를 수행하도록 순환적 순위 알고리즘이 적용된 단일형태의 버퍼 구조로 물리적인 단일 큐의 시퀀서 갖고 논리적으로 다중 큐의 형태로 구성된 ATM 스위치를 제안한다. 제안된 구조는 물리적으로 단일 버퍼를 갖지만 논리적으로는 순환적으로 순위를 결정하여 출력포트에서의 상충을 최대한 억제하도록 설계된 다중 큐의 기능을 하고 있다. 향후 이러한 형태의 구조는 다양한 구조의 라우팅을 위한 스위치로 응용되고, 시스템 구성의 확장성에 있어서도 큰 장점을 지니고 있어, 전송 효율적인 면에서도 훌륭한 구조로 평가된다.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.38 no.11
• /
• pp.804-809
• /
• 2001

In this paper, a shared channel scheme and routing algorithms are proposed to reduce the number of wavelength channels for the optical WDM multihop networks using the every-other-row-connecting bilayered ShuffleNet scheme. In the shared channel scheme proposed, 2P nodes share the common wavelength channel reducing the number of required channels compare to other ones. By assigning an effective address each node, packets can be routed to the destination nodes through the intermediate nodes.