• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.12
• /
• pp.5150-5169
• /
• 2015

Mobile Ad hoc NETworks (MANETs) are the best choice when mobility, scalability, and decentralized network infrastructure are needed. Because of critical mission applications of MANETs, network security is the vital requirement. Most routing protocols in MANETs assume that every node in the network is trustworthy. However, due to the open medium, the wide distribution, and the lack of nodes' physical protection, attackers can easily compromise MANETs by inserting misbehaving nodes into the network that make blackhole attacks. Previous research to detect the misbehaving nodes in MANETs used the overhearing methods, or additional ACKnowledgement (ACK) packets to confirm the reception of data packets. In this paper a special lightweight acknowledgement-based method is developed that, contrary to existing methods, it uses ACK packets of MAC layer instead of adding new ACK packets to the network layer for confirmations. In fact, this novel method, named PIGACK, uses ACK packets of MAC 802.11 to piggyback confirmations from a receiver to a sender in the same transmission duration that the sender sends a data packet to the receiver. Analytical and simulation results show that the proposed method considerably decreases the network overhead and increases the packet delivery ratio compared to the well-known method (2ACK).

• Journal of Information Technology Applications and Management
• /
• v.12 no.4
• /
• pp.13-24
• /
• 2005

The sensor network is a key component of the ubiquitous computing system which is expected to be widely utilized in logistics control, environment/disaster control, medical/health-care services, digital home and other applications. Nodes in the sensor network are small-sized and exposed to adverse environments. They are demanded to perform their missions with very limited power supply only. Also the sensor network is composed of much more nodes than the wireless ad hoc networks are. In case that some nodes consume up their power capacity, the network topology should change, and rerouting/retransmission is necessitated. Communication protocols studied for conventional wireless networks or ad hoc networks are not suited for the sensor network resultantly. Schemes should be devised to control the efficient usage of node power in the sensor network. This paper proposes a medium access protocol to enhance the efficiency of energy consumption in the sensor network node. Its performance is analyzed by simulation.

• 한국정보컨버전스학회:학술대회논문집
• /
• 2008.06a
• /
• pp.199-204
• /
• 2008

Sensor nodes have various energy and computational constraints because of their inexpensive nature and ad-hoc method of deployment. Considerable research has been focused at overcoming these deficiencies through faster media accessing, more energy efficient routing, localization algorithms and system design. Our research attempts to provide a method of improvement MAC performance in these issues. We show that traditional carrier-sense multiple access(CSMA) protocols like IEEE 802.11 do not handle the first constraint adequately, and do not take advantage of the second property, leading to degraded latency and throughput as the network scales in size, We present more efficient method of a medium access for real-time wireless sensor networks. Proposed MAC protocol is a randomized CSMA protocol, but unlike previous legacy protocols, does not use a time-varying contention window from which a node randomly picks a transmission slot. To reduce the latency for the delivery of event reports, it carefully decides a fixed-size contention window, non-uniform probability distribution of transmitting in each slot within the window. We show that it can offer up to several times latency reduction compared to legacy of IEEE 802.11 as the size of the sensor network scales up to 256 nodes using widely used simulator ns-2. We, finally show that proposed MAC scheme comes close to meeting bounds on the best latency achievable by a decentralized CSMA-based MAC protocol for real-time wireless sensor networks which is sensitive to latency.

• 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 the Korea Institute of Information and Communication Engineering
• /
• v.20 no.1
• /
• pp.37-44
• /
• 2016

It is important that using of efficient radio resource because of deficiency spectrum problem, so that related to this problem many researches are have proceeded. To solve this problem, Cognitive Radio(CR) was suggested. The channels are allocated to the secondary users when the primary users don't use the channels, and unfairness of secondary users can be serious problem and channel quality of multichannel can be different due to the different traffic pattern of primary users. In this paper, we propose MAC prtocol both of the user's fairness and channel quality in CR networks. Simulation results show the comparison with CR MAC protocols.

• International Journal of Contents
• /
• v.10 no.2
• /
• pp.9-17
• /
• 2014

Since vehicles' trajectories are so complex and dense traffic changes in nature frequently, the VANET (Vehicles Ad-hoc Network), using Omni-directional Antenna, has many channel collisions (or overlapping) on Data Link phrases (MAC layers). It is not easy to keep a good seamless communication status for VANET because of its unpredictable network environment. Among VANET research, Directional Antenna have been proposed as one of the most common systematical solutions to reduce (or to mitigate) this miss-communication problems by narrowing communicational ranges and making use of its customized error-detection process. However, even though Directional Antennas help VANET keep good seamless communication, many VANET researchers have reported that Directional VANET still has miss-communicational problems - this has lead to problems like 'Directional Hidden Terminal Problem', 'Deafness', 'Un-accuracy Lobe Scopes' and 'High Deployment Cost' being reported in various papers. To establish well-organized design assessments for a good Directional VANET MAC protocol to overcome these problems, we rearranged and grouped current Directional VANET' qualitative criteria from several current survey papers using these categories- 'Directional Discovery', 'Directional Forwarding' and 'Directional Handover'. In addition, based on the results of the following analysis, we show the essential design concerns that need to be looked at in order to develop a well-designed Directional-VANET MAC protocol.

• Journal of KIISE:Information Networking
• /
• v.34 no.5
• /
• pp.328-339
• /
• 2007

Conventional topology-based routing protocols are not suitable for inter-vehicular communication, where frequent route updates are necessary due to continuous and abrupt changes in network topology Position-based routing protocols are widely accepted to better serve their purpose in such a scenario as they do not require path discovery or maintenance. However they have to deal with the overhead of the location service and inaccurate position information. This paper proposes the MMFP (Multi-hop MAC Forwarding Protocol) for inter-vehicle communication that relies on reachability information collected from received packets in making a forwarding decision without path discovery. The MMFP is designed as an extension to the IEEE 802.11 MAC layer to ensure accuracy in its time-critical operations. This paper also presents some simulation results that demonstrate the superior performance of the MMFP over AODV in a realistic inter-vehicular communication.

• Proceedings of the KAIS Fall Conference
• /
• 2012.05b
• /
• pp.481-485
• /
• 2012

차량 통신 네트워크(VANET, Vehicular Ad Hoc Network)는 운전자 안전 정보 및 ITS(Intelligent Transp ortation System) 서비스를 지원하기 위해 IEEE 1609.4와 IEEE 802.11p를 활용한다. 그러나 차량 노드들의 숫자가 증가할 경우에는 트래픽 경합 문제(Traffic Contention Problem), 숨은 터미널 문제(Hidden Terminal Problem), 전송 지연 문제, 경합으로 인한 패킷 손실 문제, 처리량 감소 문제, MAC의 동적 채널 할당 방법 등 많은 문제점이 발생한다. 따라서 본 논문에서는 IEEE 1609.4와 IEEE 802.11p 기반 차량 통신 네트워크의 특징을 살펴봄으로써 기존 제안되었던 차량 통신 네트워크를 위한 MAC 및 멀티채널 기술의 특징의 장단점을 분석한다. 또한 분석된 문제점을 해결하기 위한 연구 방향을 제시한다.

• ETRI Journal
• /
• v.37 no.6
• /
• pp.1108-1119
• /
• 2015

Multicast communication of mobile ad hoc networks is vulnerable to internal attacks due to its routing structure and high scalability of its participants. Though existing intrusion detection systems (IDSs) act smartly to defend against attack strategies, adversaries also accordingly update their attacking plans intelligently so as to intervene in successful defending schemes. In our work, we present a novel indirect internal stealthy attack on a tree-based multicast routing protocol. Such an indirect stealthy attack intelligently makes neighbor nodes drop their routing-layer unicast control packets instead of processing or forwarding them. The adversary targets the collision avoidance mechanism of the Medium Access Control (MAC) protocol to indirectly affect the routing layer process. Simulation results show the success of this attacking strategy over the existing "stealthy attack in wireless ad hoc networks: detection and countermeasure (SADEC)" detection system. We design a cross-layer automata-based stealthy attack on multicast routing protocols (SAMRP) attacker detection system to identify and isolate the proposed attacker. NS-2 simulation and analytical results show the efficient performance, against an indirect internal stealthy attack, of SAMRP over the existing SADEC and BLM attacker detection systems.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.12 no.1
• /
• pp.275-281
• /
• 2012

Community network is a communication environment where heterogeneous devices can access and communicate with each other at any time and at any space to share information. To do so, mobile devices are required to be self-configured even in absence of communication infrastructures. Semi-infrastructured wireless ad-hoc network is a promising solution to meet with such a requirement. This paper proposes the VTC(virtual topology coordinator) system as an evaluation tool for examining network protocols that are intended to be deployed in the semi-infrastructured ad-hoc networks. VTC emulates multi-hops wireless network topology virtually using a mechanism of selective receiving MAC frame in a small area, where only a single hop communication is available. VTC system cannot consider all properties introduced in real wireless network, but do more wireless properties than verification through simulation.