• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5B
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• pp.247-256
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• 2007

In this paper, we propose Geographical Back-off Routing (Geo-Back Routing) protocol for wireless sensor networks. Geo-Back uses the positions of nodes, a packet's destination and a optimal back-off time to make the packet forwarding decisions using only source and destination's location information without information about neighbor nodes' location or the number of one hop neighbor nodes. Under the frequent topology changes in WSNs, the proposed protocol can find optimal next hop location quickly without broadcast algorithm for update. In our analysis, Geo-Back's scalability and better performance is demonstrated on densely deployed wireless sensor networks.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.1
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• pp.44-50
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• 2010

Wireless sensor network is consist of multiple sensor nodes and performs a shared tasks through the coordination of sensor nodes. Traffic in WSN is categorized as periodical monitoring traffic, event-driven traffic and query-based traffic. Periodic traffic takes significant proportion of the whole traffic processing because multiple sensor nodes generate traffic in a steady interval although the generation frequency of periodic traffic is low. In this paper, we propose a traffic control algorithm of network protocol for periodic traffic in terms of energy efficiency and conduct performance analysis of the algorithm.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.32-40
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• 2015

Code division multiple access (CDMA) is one of the promising medium access control scheme for underwater acoustic sensor networks due to its beneficial features such as robustness against frequency-selective fading and high frequency-reuse efficiency. In this paper, we design a closed-loop power control scheme for the underwater CDMA, to adapt time-varying acoustic channel. In the proposed scheme, sink node sends to sensor nodes the associated path loss which is acquired by uplink-channel analysis based on received packets from the sensor nodes. Then, sensor nodes adjust their transmission power in an adaptive manner to time-varying underwater acoustic channel, according to the informations sent by the sink node.

• The Journal of Korea Robotics Society
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• v.6 no.2
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• pp.97-107
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• 2011

This paper describes efficient flight control algorithms for building a reconfigurable ad-hoc wireless sensor networks between nodes on the ground and airborne nodes mounted on autonomous vehicles to increase the operational range of an aerial robot or the communication connectivity. Two autonomous flight control algorithms based on adaptive gradient climbing approach are developed to steer the aerial vehicles to reach optimal locations for the maximum communication throughputs in the airborne sensor networks. The first autonomous vehicle control algorithm is presented for seeking the source of a scalar signal by directly using the extremum-seeking based forward surge control approach with no position information of the aerial vehicle. The second flight control algorithm is developed with the angular rate command by integrating an adaptive gradient climbing technique which uses an on-line gradient estimator to identify the derivative of a performance cost function. They incorporate the network performance into the feedback path to mitigate interference and noise. A communication propagation model is used to predict the link quality of the communication connectivity between distributed nodes. Simulation study is conducted to evaluate the effectiveness of the proposed reconfigurable airborne wireless networking control algorithms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.4
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• pp.529-546
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• 2010

Greedy forwarding is the key mechanism of geographic routing and is one of the protocols used most commonly in wireless sensor networks. Greedy forwarding uses 1-hop local information to forward packets to the destination and does not have to maintain the routing table, and thus it takes small overhead and has excellent scalability. However, the signal intensity reduces exponentially with the distance in realistic wireless sensor network, and greedy forwarding consumes a lot of energy, since it forwards the packets to the neighbor node closest to the destination. Previous proposed greedy forwarding protocols are the sender-based greedy forwarding that a sender selects a neighbor node to forward packets as the forwarding node and hence they cannot guarantee energy efficient forwarding in unpredictable wireless environment. In this paper, we propose the receiver-based greedy forwarding called RGF where one of the neighbor nodes that received the packet forwards it by itself. In RGF, sender selects several energy efficient nodes as candidate forwarding nodes and decides forwarding priority of them in order to prevent unnecessary transmissions. The simulation results show that RGF improves delivery rate up to maximum 66.8% and energy efficiency, 60.9% compared with existing sender-based greedy forwarding.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.901-923
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• 2017

Efficient key distribution and management mechanisms as well as lightweight ciphers are the main pillar for establishing secure wireless sensor networks (WSN). Several symmetric based key distribution protocols are already proposed, but most of them are not scalable, yet vulnerable to a small number of compromised nodes. In this paper, we propose an efficient and scalable key management and distribution framework, named KMMR, for large scale WSNs. The KMMR contributions are three fold. First, it performs lightweight local processes orchestrated into upward and downward tiers. Second, it limits the impact of compromised nodes to only local links. Third, KMMR performs efficient secure node addition and revocation. The security analysis shows that KMMR withstands several known attacks. We implemented KMMR using the NesC language and experimented on Telosb motes. Performance evaluation using the TOSSIM simulator shows that KMMR is scalable, provides an excellent key connectivity and allows a good resilience, yet it ensures both forward and backward secrecy. For a WSN comprising 961 sensor nodes monitoring a 60 hectares agriculture field, KMMR requires around 2.5 seconds to distribute all necessary keys, and attains a key connectivity above 96% and a resilience approaching 100%. Quantitative comparisons to earlier work show that KMMR is more efficient in terms of computational complexity, required storage space and communication overhead.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.8
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• pp.2042-2060
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• 2013

In wireless sensor networks (WSNs), energy efficiency is one of the most essential design considerations, since sensor nodes are resource constrained. Group communication can reduce WSNs communication overhead by sending a message to multiple nodes in one packet. In this paper, in order to simultaneously resolve the transmission security and scalability in WSNs group communications, we propose a hierarchical cluster-based secure and scalable group key management scheme, called HRKT, based on logic key tree and route key tree structure. The HRKT scheme divides the group key into cluster head key and cluster key. The cluster head generates a route key tree according to the route topology of the cluster. This hierarchical key structure facilitates local secure communications taking advantage of the fact that the nodes at a contiguous place usually communicate with each other more frequently. In HRKT scheme, the key updates are confined in a cluster, so the cost of the key updates is reduced efficiently, especially in the case of massive membership changes. The security analysis shows that the HRKT scheme meets the requirements of group communication. In addition, performance simulation results also demonstrate its efficiency in terms of low storage and flexibility when membership changes massively.

• ETRI Journal
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• v.38 no.6
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• pp.1145-1152
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• 2016

Because the nodes in a wireless sensor network (WSN) are mobile and the network is highly dynamic, monitoring every node at all times is impractical. As a result, an intruder can attack the network easily, thus impairing the system. Hence, detecting anomalies in the network is very essential for handling efficient and safe communication. To overcome these issues, in this paper, we propose a rule-based anomaly detection technique using roaming honeypots. Initially, the honeypots are deployed in such a way that all nodes in the network are covered by at least one honeypot. Honeypots check every new connection by letting the centralized administrator collect the information regarding the new connection by slowing down the communication with the new node. Certain predefined rules are applied on the new node to make a decision regarding the anomality of the node. When the timer value of each honeypot expires, other sensor nodes are appointed as honeypots. Owing to this honeypot rotation, the intruder will not be able to track a honeypot to impair the network. Simulation results show that this technique can efficiently handle the anomaly detection in a WSN.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.11
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• pp.1146-1150
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• 2014

Recently, there has been interests in smart vessel technology, and it needs to consider an intelligent control system for efficient vessel manangement. In a smart vessel, however, it can cause a network overload due to a number of data transmission from a variety of sensor nodes and bridge nodes. In this letter, we propose an data transmission scheme with data fusion to reduce the number of traffic from the sensor nodes. Hence it can decrease network overload for intelligent vessel management.

• Journal of Internet Computing and Services
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• v.10 no.2
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• pp.41-51
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• 2009

Recently, there are many researches on security to remove vulnerability which is caused by wireless communication in wireless sensor networks. To guarantee secure communication, we should basically provide key management for each node, mutual authentication and key agreement protocol between two nodes. Although many protocols are presented to supply these security services, some of them require plentiful storage memory, powerful computation and communication capacity. In this paper, we propose a lightweight and efficient authentication and key agreement protocol between two sensor nodes, which is an enhanced version of Juang's scheme. In Juang's protocol, sensor node's information used to share a secret key should be transmitted to registration center via a base station. On the contrary, since node's information in our protocol is transmitted up to only base station, the proposed scheme can decrease computation and communication cost for establishing the shared key between two nodes.