• Journal of the Korea Society of Computer and Information
• /
• v.15 no.12
• /
• pp.75-84
• /
• 2010

As broadcasting in Mobile Ad hoc NETwork (MANET) is the process that a node sends a packet to all other nodes in the network. it is used for routing protocols such as Ad hoc On demand Distance Vector (AODV) to disseminate control information for establishing the routes. In this paper, we propose Probabilistic Broadcasting mechanism based on Distance Ratio between sender and receive node in MANETs. The proposed approach is based on the combination of probability and distance based approach. A mobile node receiving broadcast packets determines the probability of rebroadcasting considering distance ratio from sender. The distance ratio of a node is calculated by the distance from sender and the length of radio field strength. As a node with high distance ratio is located far away from sender, rebroadcast probability is set to high value. On contrary, the low rebroadcast probability is set for a node with low distance ratio which is close to sender. So it reduces packets transmission caused by the early die-out of rebroadcast packets. Compared with the simple flooding and fixed probabilistic flooding by simulation, our approach shows better performances results. Proposed algorithm can reduce the rebroadcast packet delivery more than 30% without scanting reachability, where as it shows up to 96% reachability compared with flooding.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.5B
• /
• pp.925-930
• /
• 2000

The Problem of allocating paths is very significant in order to transmit a large amount of various data on the ATM network. Therefore, selecting an optimal path among available paths between the a source node and a target node has been researched. Alternate paths designed in previous PNNI routing is not considered on the group-occupation so that traffic congestion happens, when errors occur in the network which consists of a hierarchical network architecture extendable to a large network, We propose the Top-Down algorithm considering an average of the occupation among the groups reported from a leader node in each group and minimizing a traffic congestion

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.06d
• /
• pp.115-117
• /
• 2006

IEEE 802.11 표준은 채널 상태에 따라 다양한 전송 속도를 지원하며, 무선랜 환경에서 이러한 특성을 활용하는 연구들이 진행되어 왔다. 그러나, 모바일 애드 혹 네트워크 환경에서 다중전송속도를 활용하는 연구는 거의 이루어지지 않았다. 본 논문은 모바일 애드 혹 네트워크에서 동적으로 다중전송속도를 활용하여 채널 효율을 높이는 알고리즘을 제안한다. 제안 기법은 MAC 계층과 네트워크 계층 중간에 위치하며 각 계층에 독립적으로 동작한다. 라우팅 프로토콜에서 결정한 다음 홉에 더불어, 제안 기법은 더 빠른 전송 속도를 갖는 중계 경로를 탐색한다. 또한, 패킷의 크기에 따라 경쟁 부하를 고려하여 선택적으로 전송 경로를 변경한다. 모의 실험을 통한 성능 평가는 제안 기법의 우수한 성능을 입증한다.

• Proceedings of the Korea Society for Simulation Conference
• /
• 2005.11a
• /
• pp.108-112
• /
• 2005

유비쿼터스 컴퓨팅의 기반 설비인 센서 네트워크는 많은 수의 센서 노드들로 구성되며, 각 센서 노드의 하드웨어는 매우 작은 규모이다. 또한 센서 네트워크는 구축 목적에 따라 네트워크 토폴로지 및 라우팅 방식이 결정되어야 하고, 이와 더불어 센서 노드의 하드웨어와 소프트웨어도 필요에 따라 다양하게 변경되어야 한다. 따라서 센서 네트워크가 구현되기 전에 시스템 동작과 성능을 예측할 수 있는 센서 네트워크 시뮬레이터가 필요하다. 기존의 센서 네트워크 시뮬레이터들은 특별한 응용을 위한 특정 기반의 하드웨어와 운영체제에 국한되어 개발되었기 때문에 다양한 센서 네트워크 환경을 지원하기에는 한계가 있으며, 센서 네트워크 설계상의 주요 요소인 전력소모량과 실행 시간에 대한 분석이 포함되지 않았다. 따라서 본 연구에서는 특정한 응용이나 운영체제에 제한을 받지 않으면서 다양하게 센서 네트워크 환경을 설계 및 검증할 수 있고, 더불어 전력소모량과 실행시간 추정도 가능한 시뮬레이터를 개발하는 것을 목표로 하였다. 이를 위해 본 연구에서 개발한 시뮬레이터는 기계명령어-레벨(machine instruction-level)의 이산-사건 시뮬레이션(discrete-event simulation) 기법을 이용함으로써 실제 센서 노드의 프로그램 실행 및 관련 동작들을 세부적으로 예측하는 데 사용될 수 있도록 하였다. 시뮬레이션의 작업부하(workload)인 명령어 트레이스(instruction trace)로는 ATmega128L 마이크로컨트롤러용으로 크로스 컴파일된 인텔 핵스-레코드(.hex) 형식을 사용한다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2009.04a
• /
• pp.1178-1181
• /
• 2009

Geographic forwarding algorithms을 사용하는 Georouting protocol에서는 route maintenance을 위해서 고정된 주기마다 beacon message을 이웃노드에 전송하는 fixed periodical beacon based route algorithm을 사용하여 mobile node 정보를 습득한다. Fixed periodical beacon scheme에서의 기존 연구 이슈는 이웃노드 정보의 신뢰성을 유지하기 위해서 다양한 mobility environment 환경에 맞도록 beacon 전송주기를 적절히 결정하는 연구가 진행되어 왔다. 이와 같은 연구에서는 long periodical interval 사용 시 이웃노드의 위치정보 error을 발생시킬 확률이 높으며 또한 short periodical interval 의 경우 네트워크 내에 high route overhead 을 유발시키는 단점을 가지고 있다. 따라서 고정된 주기 방법은 다양한 mobility environment에 잘 적용되지 못하며 또한 mobility environment 에서 발생하는 route maintenance 내에 이웃노드 정보에 대한 불확실성 문제가 빈번이 발생하여 경로 설정에 잘못된 정보를 제공하여 경로 신뢰성(path reliability)과 낮은 전송률 (transmission rate)을 야기한다. 본 논문에서는 이런 이웃노드 정보의 불확실성 문제를 극복하기 위해서 mobile node가 스스로 자신의 위치를 체크하여 routing table을 능동적으로 갱신하는 방법을 이용하여 이 문제를 극복할 수 있도록 하였다. 모의 실험은 ns2를 이용하여 실시하였으며 결과는 low/high mobility scenario에서는 기존 방법 보다 routing overhead 을 줄이면서 높은 전송률 (transmission rate)을 보인다.

• Journal of Korea Spatial Information System Society
• /
• v.9 no.3
• /
• pp.35-50
• /
• 2007

In a data centric sensor network, a sensor node to store data is determined by the measured data value of each sensor node. Therefore, if the same data occur frequently, the energy of the sensor node to store the data is exhausted quickly due to the concentration of loads. And if the sensor network is extended, the communication cost for storing data and processing queries is increased, since the length of the routing path for them is usually in the distance. However, the existing researches that generally focus on the efficient management of data storing can not solve these problems efficiently. In this paper, we propose a NUNS(Non-Uniform Network Split) method that can distribute loads of sensor nodes and decrease the communication cost caused by the sensor network extension. By dividing the sensor network into non-uniform partitions that have the minimum difference in the number of sensor nodes and the splitted area size and storing the data which is occurred in a partition at the sensor nodes within the partition, the NUNS can distribute loads of sensor nodes and decrease the communication cost efficiently. In addition, by dividing each partition into non-uniform zones that have the minimum difference in the splitted area size as many as the number of the sensor nodes in the partition and allocating each of them as the processing area of each sensor node, the NUNS can protect a specific sensor node from the load concentration and decrease the unnecessary routing cost.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.12B
• /
• pp.1749-1757
• /
• 2010

This paper considers the cost minimization problem to satisfy QoS (Quality of Service) requirements for a given network, in particular when communication resources to each link can be additionally assigned. For the purpose of quantifying QoS requirements such as data transfer delay and packet loss, we introduce the cost function considering both the link utilization factor and the additionally assigned resource. To minimize this cost function, we firstly formulate a Basic Capacity Planning (BCP) problem, a special case of Network Utility Maximization (NUM). We show that the solution of this BCP problem cannot be optimal via a counter example. In this paper, we suggest the cross-layer design of both additionally assigned resource and routing path, whose initial values are set to the result of BCP problem. This cross-layer design is based on a heuristic approach which presents an effective way to plan how much communication resources should be added to support the QoS requirements in future. By simulation study, we investigate the convergence of the cost function in a more general network topology as well as in a given simple topology.

• The KIPS Transactions:PartC
• /
• v.10C no.3
• /
• pp.377-386
• /
• 2003

This study suggested a technique to maintain an efficient core-based multicast tree using weighted clustering factors in mobile Ad-hoc networks. The biggest problem with the core-based multicast tree routing is to decide the position of core node. The distance of data transmission varies depending on the position of core node. The overhead's effect on the entire network is great according to the recomposition of the multicast tree due to the movement of core node, clustering is used. A core node from cluster head nodes on the multicast tree within core area whose weighted factor is the least is chosen as the head core node. Way that compose multicast tree by weighted clustering factors thus and propose keeping could know that transmission distance and control overhead according to position andmobility of core node improve than existent multicast way, and when select core node, mobility is less, and is near in center of network multicast tree could verification by simulation stabilizing that transmission distance is short.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.12 no.4
• /
• pp.81-93
• /
• 2012

We propose efficient mobility management schemes based on pointer forwarding for Proxy Mobile IPv6 Networks(PMIPv6) with the objective to reduce the overall network traffic incurred by mobility management and packet delivery. The proposed schemes are per-user-based, i.e., the optimal threshold of the forwarding chain length that minimizes the overall network traffic is dynamically determined for each individual mobile user, based on the user's specific mobility and service patterns. We demonstrate that there exists an optimal threshold of the forwarding chain length, given a set of parameters characterizing the specific mobility and service patterns of a mobile user. We also demonstrate that our schemes yield significantly better performance than schemes that apply a static threshold to all mobile users. A comparative analysis shows that our pointer forwarding schemes outperform routing-based mobility management protocols for PMIPv6.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.12
• /
• pp.2800-2807
• /
• 2012

An ad-hoc wireless network provides self-organizing data networking while they are routing of packets among themselves. Typically multi-hop and control packets overhead affects the change of route of transmission. There are numerous routing protocols have been developed for ad hoc wireless networks as the size of the network scale. Hence the scalable routing protocol would be needed for energy efficient various network routing environment conditions. The number of depth or layer of hierarchical clustering nodes are analyzed the different clustering structure with topology in this paper. To estimate the energy efficient number of cluster layer and energy dissipation are studied based on distributed homogeneous spatial Poisson process with context-awareness nodes condition. The simulation results show that CACHE-R could be conserved the energy of node under the setting the optimal layer given parameters.