• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.5
• /
• pp.41-46
• /
• 2011

Mobile Ad-Hoc networks (MANET) has been getting the spotlight in the area of the wireless networks because of its flexibility and salability, and developing of many applications with it. As a consequence, MANETs are required to process not only simple data traffics, but also multimedia traffics, which has some constraints on the performances. However, unlike wired-networks, the wireless networks have frequent route-disconnections due to some reasons such as channel errors and mobility. Such frequent link disconnections makes the delivery of multimedia traffics difficult. Even though there many researches on multimedia transmissions on various environments, the performances of multimedia transmissions over fading channel and mobility even using various routing protocols have not been evaluated. Therefore, this paper extensively simulates the MPEG-4 video transmission over fading channel environment with node's mobility. In addition, the performances with two routing protocols such as AODV and DSR are compared. Finally, the simulation results shows that DSR protocol has the better performances to deliver MPEG-4 traffic.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37C no.11
• /
• pp.1148-1161
• /
• 2012

Recently, developments in the field of communication and network technologies induced new paradigm in the defense weapon system. As a consequence, military authorities develop the Tactical Information Communication Network(TICN) system to adapt to the changing paradigm. One of the most important functions of TICN is real-time communication. As a result, TICN system needs to receive real-time information from the battlefield, and the key technology to support these features is MANET(Mobile Ad-Hoc Network) routing protocol. In this paper, we analyze problems of the shortest path scheme in tactical Ad-Hoc networks, which is widely used in common Ad-Hoc networks. We propose efficient routing protocol for tactical MANET by considering the environment of small combat units, such as node position, speed and data size. The proposed algorithm shows reliable data transfer and low latency in battlefield.

• Journal of KIISE:Information Networking
• /
• v.29 no.3
• /
• pp.224-232
• /
• 2002

The routing protocols designed for wired networks can hardly be used for mobile ad-hoc networks due to limited bandwidth of wireless transmission and unpredictable topological change. Recently, several routing protocols for mobile ad-hoc networks have been proposed. However, when these protocols are applied to support real time services like multimedia transmission, they still have problems in ad-hoe networks, where the topology changes drastically. In this paper, we propose a new route selection algorithm which selects the most reliable rouse that is impervious to route failures by topological changes by mobile hosts. For reliable route selection, the concept of virtual zone (stable lone and caution zone) is proposed. The lone is located in a mobile node's transmission range and determined by mobile node's mobility information received by Global Positioning System (GPS). The proposed algorithm is applied to the route discovery procedure of the existing on-demand routing protocol, AODV, and evaluated by simulation in various traffic conditions and mobility patterns.

• Journal of Internet Computing and Services
• /
• v.7 no.6
• /
• pp.175-183
• /
• 2006

An ad-hoc network is a group of mobile nodes acting as routers. The of hoc node has a precondition of mobility, allowing path to be easily disconnected when transmitting data, thereby increasing network overhead. However, most of hoc routing protocols set up the path based only on the number of hops without considering other practical factors. Here we consider a path with the least substantial number of transmission (SNT) from source to destination based on reliabilities of links. This includes retransmissions due to unreliable links. In this paper, an efficient ad-hoc link reliability based routing (PU) protocol suitable for mobile ah-hoc network in terms of SNT, is proposed. The network overhead and data transmission delay ore reduced, by considering both ad-hoc link reliability and the number of hops. Our empirical performance evaluation comparing to AODV (8) shows that the enhancement is up to about 31% for SNT depending upon the mobility of nodes.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.1B
• /
• pp.16-23
• /
• 2009

This paper investigates how many optimal routes can be established in terms of a given wireless mesh routing metric. Although many of routing metrics have been devised to precisely derive the wireless link quality in mesh, most (if not all) metrics have not been evaluated their optimality along with routing protocols. We consider stateof-the-art routing metrics and a widely accepted routing protocol in order to observe the optimality of established routes varying the number of source nodes. Also, we propose a unidirectional routing to deal with possible link asymmetry feature in wireless links. Through comparative simulation evaluations, we show that the portion of optimally established routes becomes less as the network traffic load increases, regardless of employed metrics, network topologies, and routing protocols.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.23 no.4
• /
• pp.371-380
• /
• 2020

Video is principal information that facilitates commander's immediate command decision. Due to fading characteristics of radio link, however, it is difficult to stably transmit video in a multi-hop wireless environment. In this paper, we propose a MANET structure composed of a link adaptive routing protocol and a TDMA MAC protocol to stably transmit video traffic in a ultra-narrowband video streaming network. The routing protocol can adapt to link state change and select a stable route. The TDMA protocol enables collision-free video transmission to a destination using multi-hop dynamic resource allocation. As a result of simulation, the proposed MANET structure shows better video transmission performance than proposed MANET structure without link quality adaption, AODV with CSMA/CA, and OLSR with CSMA/CA structures.

• Journal of Communications and Networks
• /
• v.9 no.3
• /
• pp.296-311
• /
• 2007

Mobile multi-robot teams are useful in many critical applications such as search and rescue. Explicit communication among robots in such mobile multi-robot teams is useful for the coordination of such teams as well as exchanging data. Since many applications for mobile robots involve scenarios in which communication infrastructure may be damaged or unavailable, mobile robot teams frequently need to communicate with each other via ad hoc networking. In such scenarios, low-overhead and energy-efficient routing protocols for delivering messages among robots are a key requirement. Two important primitives for communication are essential for enabling a wide variety of mobile robot applications. First, unicast communication (between two robots) needs to be provided to enable coordination and data exchange. Second, in many applications, group communication is required for flexible control, organization, and management of the mobile robots. Multicast provides a bandwidth-efficient communication method between a source and a group of robots. In this paper, we first propose and evaluate two unicast routing protocols tailored for use in ad hoc networks formed by mobile multi-robot teams: Mobile robot distance vector (MRDV) and mobile robot source routing (MRSR). Both protocols exploit the unique mobility characteristics of mobile robot networks to perform efficient routing. Our simulation study show that both MRDV and MRSR incur lower overhead while operating in mobile robot networks when compared to traditional mobile ad hoc network routing protocols such as DSR and AODV. We then propose and evaluate an efficient multicast protocol mobile robot mesh multicast (MRMM) for deployment in mobile robot networks. MRMM exploits the fact that mobile robots know what velocity they are instructed to move at and for what distance in building a long lifetime sparse mesh for group communication that is more efficient. Our results show that MRMM provides an efficient group communication mechanism that can potentially be used in many mobile robot application scenarios.

• The KIPS Transactions:PartC
• /
• v.15C no.2
• /
• pp.79-86
• /
• 2008

MANET(Mobile Ad hoc Network) is a collection of two or more nodes equipped with wireless communications and constrained by the factor of energy limitation. The running out of energy on some nodes may bring down the performance of network seriously. For solving the problems above, this paper uses completely separated Node-Disjoint multipaths from a source to a destination as many as possible. And, based on average, minimum or variance of energy values on the each multipath, the packets are distributed on paths. Generally, collecting methods for energy information can be classified into two main categories, Static and Dynamic. As the different energy values collected, the packet distribution methods are classified into six criteria, Static-Average, Static-Minimum, Static-Variance, Dynamic-Average, Dynamic-Minimum and Dynamic-Variance respectively. The performance of the packet distribution methods and that of AODV are compared by NS2 simulation.

• Annual Conference of KIPS
• /
• 2010.11a
• /
• pp.863-866
• /
• 2010

무선 센서 네트워크의 규모가 커짐에 따라 대규모의 센서 네트워크의 활용에 대한 기대가 커지고 있다. 기존 IEEE 802.15.4 를 이용한 네트워크의 규모에 따른 한계를 극복하기 위해 듀얼 라디오 센서 네트워크에 대한 많은 연구가 진행되고 있다. 듀얼 라디오 센서 네트워크는 단일 라디오를 내장한 전통적인 센서 노드(싱글 라디오 노드)에 듀얼 라디오 인터페이스(IEEE 802.11g, IEEE 802.15.4)를 내장한 센서(듀얼 라디오 노드)를 포함하여 클러스터를 구성한다. 본 논문에서는 이러한 듀얼 라디오 환경에서 효과적으로 동작하는 라우팅 프로토콜을 제안한다. 듀얼 라디오 노드는 네트워크 상에서 클러스터 헤드 역할을 하고 상위 계층을 이루며, 일반 노드는 클러스터 멤버 역할을 하는 하위 계층을 이룬다. 본 논문에서는 각 계층의 네트워크가 나타내는 특징을 이동성이 적거나 높은 네트워크의 특징으로 대입하여, 상위 계층에는 Pro-Active 프로토콜, 하위 계층에는 Re-active 프로토콜이 효과적임을 설명한다. 이를 바탕으로 듀얼 라디오 센서 네트워크에 적합한 라우팅 프로토콜로써 Pro-Active 프로토콜을 대표하는 DSDV 와 Re-Active 프로토콜을 대표하는 AODV 를 조합한 하이브리드 라우팅 프로토콜을 제안한다. 제안한 프로토콜의 성능을 확인하기 위해 센서네트워크 테스트베드를 구성하여 라우팅 복구 시간과 패킷 전송 안정성에 대한 성능을 입증한다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.9
• /
• pp.751-764
• /
• 2013

In cognitive radio ad-hoc networks, common control channel overload and packet collisions are occured due to indiscriminate broadcasting of control packets. So that the path reliability is reduced and control channel is easily saturated. In this paper, we propose a new routing algorithm considering the probability of appearance of primary user and channel status of neighbor nodes. When the source node needs to transmit a data packet to the destination, it performs route discovery process by exchanging control messages using a control channel in ADOV CR Ad-hoc networks. If any intermediate node doesn't have common data channel with previous node to transmit data, it doesn't rebroadcast control packet. And if it has common data channels with previous node, each node determines channel contribution factor with the number of common channels. Based on the channel contribution factor, each node performs different back-off broadcasting. In addition, each node controls control packet flooding by applying to proposed advanced mode using such as number of available channels and channel stability. With the proposed method, the number of control packets to find the data transmission path and the probability of collision among control packets can be decreased. While the path reliability can be increased. Through simulation, we show that our proposed algorithm reduces packet collisions in comparison with the traditional algorithm.