• Journal of the Korea Society of Computer and Information
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• v.21 no.3
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• pp.25-32
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• 2016

Mobile Ad Hoc Networks(MANETs) consists of mobile nodes which communicate with each other without any centralized infrastructure. Message broadcasting by flooding for route discovery in MANET can result in high redundant retransmission, contention and collision of broadcasting packet, known as the broadcast storm problem collectively. The cross-layer design is adopted in this paper, which lets routing layer share the received signal strength information at MAC layer. Also this paper proposes a new probabilistic approach that dynamically adjusts the rebroadcasting probability of a node for routing request packets (RREQs) according to the received signal strength. The simulation results show that the proposed approach demonstrates better performance than blind flooding, fixed probabilistic broadcasting approaches.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.12
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• pp.1256-1262
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• 2012

Mobile ad hoc networks (MANETs) are infrastructure-less, autonomous, and stand-alone wireless networks with dynamic topologies. Recently, cluster-based ad hoc networks which enhance the security and efficiency of ad hoc networks are being actively researched. And routing protocols for cluster-based ad hoc networks are also studied. However, there are few studies about secure routing protocols in cluster-based ad hoc networks. In this paper, we propose secure routing protocol for cluster-based ad hoc networks. We use Diffie-Hellman key agreement, HMAC, and digital signature to support integrity of routing messages, and finally can perform secure routing.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.9
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• pp.666-676
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• 2006

Rapid advances in ubiquitous computing and its pervasive influence over our society demand an efficient way to locate resources over the network. In mobile ad-hoc networks (MANETs) which is a special type of the sub-networks in ubiquitous environment, effective resource discovery is particularly important, due to their dynamics and the resource constraints on wireless nodes. In this paper, we propose an adaptive and efficient resource discovery strategy for MANETs. Our strategy also provides a solution to bridge different types of networks which coexist in ubiquitous environment.

• Journal of the Korean Data and Information Science Society
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• v.19 no.2
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• pp.645-655
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• 2008

As wireless connectivity is integrated into many handheld devices, streaming multimedia content among mobile ad-hoc peers is becoming a popular application. In this paper, we propose a dynamic service replication algorithm for providing guaranteed continuous streaming services to all nodes in mobile ad-hoc networks (MANETs). First, a MANET is comprised of logical grid hierarchy, and a streaming service is replicated to a lower server region of the logical grid hierarchy by considering the link availability between a mobile node and the streaming server within a server region or the popularity of the streaming service. We evaluate analytically the performance of the proposed algorithm, and compared with that of existing Qin's algorithm. Evaluation results show that our algorithm can achieve better streaming performance than Qin's algorithm. Therefore, the proposed algorithm not only improves the sharing availability of replicated streaming services but also controls efficiently the number of streaming service replications.

• Journal of Communications and Networks
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• v.11 no.3
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• pp.248-260
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• 2009

To connect a mobile ad hoc network (MANET) with an IP network and to carryout communication, ad hoc network node needs to be configured with unique IP adress. Dynamic host configuration protocol (DHCP) server autoconfigure nodes in wired networks. However, this cannot be applied to ad hoc network without introducing some changes in auto configuration mechanism, due to intrinsic properties (i.e., multi-hop, dynamic, and distributed nature) of the network. In this paper, we propose a scalable autoconfiguration scheme for MANETs with hierarchical topology consisting of leader and member nodes, by considering the global Internet connectivity with minimum overhead. In our proposed scheme, a joining node selects one of the pre-configured nodes for its duplicate address detection (DAD) operation. We reduce overhead and make our scheme scalable by eliminating the broadcast of DAD messages in the network. We also propose the group leader election algorithm, which takes into account the resources, density, and position information of a node to select a new leader. Our simulation results show that our proposed scheme is effective to reduce the overhead and is scalable. Also, it is shown that the proposed scheme provides an efficient method to heal the network after partitioning and merging by enhancing the role of bordering nodes in the group.

• Journal of information and communication convergence engineering
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• v.9 no.5
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• pp.610-614
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• 2011

Nowadays Mobile Ad Hoc Networks (MANETs) are a very popular and emerging technology in the world. MANETs helps mobile nodes to communicate with each other anywhere without using infrastructure. For this purpose we need good routing protocols to establish the network between nodes because mobile nodes can change their topology very fast. Mobile node movements are very important features of the routing protocol. They can have a direct effect on the network performance. In this paper, we are going to discuss random walk and random waypoint mobility models and their effects on routing parameters. Previously, mobility models were used to evaluate network performance under the different routing protocols. Therefore, the network performance will be strongly modeled by the nature of the mobility pattern. The routing protocols must rearrange the changes of accurate routes within the order. Thus, the overheads of traffic routing updates are significantly high. For specific network protocols or applications, these mobility patterns have different impacts.

• Journal of Computing Science and Engineering
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• v.4 no.3
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• pp.225-239
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• 2010

This paper introduces a new approach to modeling relative distance among nodes under a variety of communication rates, due to node's mobility in Mobile Ad-hoc Networks (MANETs). When mobile nodes move to another location, the relative distance of communicating nodes will directly affect the data rate of transmission. The larger the distance between two communicating nodes is, the lower the rate that they can use for transferring data will be. The connection certainty of a link also changes because a node may move closer to or farther away out of the communication range of other nodes. Therefore, the stability of a route is related to connection entropy. Taking into account these issues, this paper proposes a new routing metric for MANETs. The new metric considers both link weight and route stability based on connection entropy. The problem of determining the best route is subsequently formulated as the minimization of an object function formed as a linear combination of the link weight and the connection uncertainty of that link. The simulation results show that the proposed routing metric improves end-to-end throughput and reduces the percentage of link breakages and route reparations.

• International Journal of Contents
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• v.2 no.2
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• pp.29-31
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• 2006

Mobile Ad hoc network is a self configuring network of mobile nodes. It allows mobile nodes to configure network spontaneously and share their services. In these networks, service discovery is very important because all nodes do not have same resources in term of memory and computing power. Nodes need to use different services offered by different servers. Some service discovery protocols have been proposed in last couple of years but they include significant traffic overhead and for small scale MANETS. In this paper, we present extensible lookup service scheme based on distributed mechanism. In our scheme neighboring nodes of service provider monitor service provider and send notification to lookup server when the service provider terminates its services unexpectedly. Lookup server can find other service provider or other alternative services in advance because of advance notification method and can provide consistent lookup services. In our scheme neighboring nodes also monitor lookup server and send notification to network when lookup server terminates unexpectedly. Simulation results show that our scheme can reduce up to 70% and 30% lookup failure as compare to centralize and simple distributed mechanism respectively.

• Journal of information and communication convergence engineering
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• v.10 no.4
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• pp.329-336
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• 2012

For designing broadcast protocols in mobile ad hoc networks (MANETs), one of the important goals is to reduce the rebroadcast packets redundancy while reaching all the nodes in network. In this paper, we propose a probabilistic broadcasting mechanism based on selfishness and additional coverage in MANETs. Our approach dynamically adjusts the rebroadcast probability according to the extra covered area and number of neighbor nodes. By these two factors, mobile hosts can be classified into three groups: normal, low selfishness, and high selfishness groups. The nodes in the normal group forward packets for other nodes with high probability, whereas the nodes in the low selfishness group rebroadcast packets with low probability and the nodes in the high selfishness group do not rebroadcast packets. We compared our approach with simple flooding and the fixed probabilistic approach. The simulation results show that the proposed schemes can significantly reduce the number of retransmissions by up to 40% compared simple flooding and fixed probabilistic scheme without significant reduction in the network reachability and end-to-end packet delay.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.147-151
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• 2014

With the advent of tiny and inexpensive computer systems like Raspberry Pi, it has become possible to construct an experimental environment of MANETs (Mobile Ad hoc Networks) at a relatively low cost. In this paper, we implement a node of MANETs with a Raspberry Pi equipped with two 802.11 wireless LAN cards and dynamic routing software running on it. In an outdoor MANETs environment with moving mobile nodes automatically rebuilding broken routes, we conducted a real-time video streaming experiment over the MANET. The video stream is transmitted from a node with a video camera installed on it to another node through the route established dynamically. Each node is equipped with a display device, with which the current status of the node can be checked out. We also implemented software that automatically collects data stored in each node and analyzes the performance of the MANETs. Through this experiment, we could evaluate the performance of realistic video streaming service in a MANETs environment.