• ETRI Journal
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• v.33 no.5
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• pp.791-801
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• 2011

Security in wireless sensor networks (WSNs) is an upcoming research field which is quite different from traditional network security mechanisms. Many applications are dependent on the secure operation of a WSN, and have serious effects if the network is disrupted. Therefore, it is necessary to protect communication between sensor nodes. Key management plays an essential role in achieving security in WSNs. To achieve security, various key predistribution schemes have been proposed in the literature. A secure key management technique in WSN is a real challenging task. In this paper, a novel approach to the above problem by making use of elliptic curve cryptography (ECC) is presented. In the proposed scheme, a seed key, which is a distinct point in an elliptic curve, is assigned to each sensor node prior to its deployment. The private key ring for each sensor node is generated using the point doubling mathematical operation over the seed key. When two nodes share a common private key, then a link is established between these two nodes. By suitably choosing the value of the prime field and key ring size, the probability of two nodes sharing the same private key could be increased. The performance is evaluated in terms of connectivity and resilience against node capture. The results show that the performance is better for the proposed scheme with ECC compared to the other basic schemes.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3A
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• pp.269-278
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• 2010

There are tendency that wireless sensor network is one of the important techniques for the future IT industry and thereby application areas in it are getting growing. Researches based on the hierarchical network topology are evaluated in good at energy efficiency in related protocols for wireless sensor network. LEACH is the best well known routing protocol for the hierarchical topology. However, there are problems in the range of message broadcasting, which should be expand into the overall network coverage, in LEACH related protocols. This dissertation proposes a new routing protocol to solve the co-shared problems in the previous protocols. The basic idea of our scheme is using the table for nodes connectivity and node energy information. The results show that the proposed protocol could support the load balancing by distributing the clusters with a reasonable number of member nodes and thereby the network life time would be extended in about 1.8 times longer than LEACH.

• Journal of the Korean Geographical Society
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• v.45 no.6
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• pp.788-805
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• 2010

The present USN (Ubiquitous Sensor Networks) node deployment practices have many limitations in terms of positional connectivity. The aim of this research was to minimize a redundancy of USN route nodes, by integrating spatially weighted parameters such as visibility, proximity to cell center, road density, building density and cell overlapping ratio into a comprehensive GIS database. This spatially weighted approach made it possible to reduce the number of route nodes (11) required in the study site as compared to that of the grid network method (24). The field test for RSSI (Received Signal Strength Indicator) indicates that the spatially weighted deployment could comply with the quality assurance standard for node connectivity, and that reduced route nodes do not show a significant degree of signal fluctuation for different site conditions. This study demonstrated that the spatially weighted deployment can be used to minimize a redundancy of USN route nodes in a routine manner, and the quantitative evidence removing a redundancy of USN route nodes could be utilized as major tools to ensure the strong signal in the USN, that is frequently encountered in real applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9A
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• pp.1395-1404
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• 2000

In this paper, we propose a heuristic wavelength routing algorithm for IP datagrams in WDM (Wavelength-Division Multiplexing) networks which operates in a distributed manner, while most previous works have focused centralized algorithms. We first present an efficient construction method for a loose virtual topology with a connectivity property, which reserves a few wavelength to cope with dynamic traffic demands properly. This connectivity property assures that data from any source node could reach any destination node by hopping one or multiple lightpaths. We then develop a high-speed distributed wavelength routing algorithm adaptive to dynamic traffic demands by using such a loose virtual topology and derive the general bounds on average utilization in the distributed wavelength routing algorithms. Finally, we show that the performance of the proposed algorithms is better than that of the FSP(Fixed Shortest-Path) wavelength routing algorithms through simulation using the NSFNET[1] and a dynamic hot-spot traffic model, and that the algorithms is a good candidate in distributed WDM networks in terms of the blocking performance, the control traffic overhead, and the computation complexity.

• Smart Media Journal
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• v.10 no.2
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• pp.84-91
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• 2021

In the EU GDPR, when collecting personal information, the right of the information subject(user) to consent or refuse is given the highest priority. Therefore, the information subject must be able to withdraw consent and be forgotten and claim the right at any time. Especially, restricted IoT devices(Constrained Node) implement the function of consent of the data subject regarding the collection and processing of privacy data, and it is very difficult to post the utilization content of the collected information. In this paper, we designed and implemented a management system that allows data subjects to monitor data collected and processed from IoT devices, recognize information leakage problems, connect, and control devices. Taking into account the common information of the standard OCF(Open Connectivity Foundation) of IoT devices and AllJoyn, a device connection framework, 10 meta-data for information protection were defined, and this was named DPD (Data Protection Descriptor). we developed DPM (Data Protection Manager), a software that allows information subjects to manage information based on DPD.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.16-27
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• 2014

In this paper, we propose an efficient grid based routing scheme using the location information in order to reduce the routing cost in mobile ad-hoc networks. In our proposed scheme, all nodes can be a candidate to forward messages to the specified destination node and reduce the management cost of head nodes because they do not exist. The intermediate nodes determine the next hop relaying messages on the basis of location relations between a node and a grid zone. The proposed scheme explores the routing path considering the direction of a node using the coordinate of a grid zone and neighbor node information. It also maintains the routing path considering connectivities among the nodes. In order to show the superiority of the proposed routing scheme, we compare it with the existing grid based routing scheme in terms of the overhead of message, the success rate of transmission.

• Journal of Internet Computing and Services
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• v.15 no.4
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• pp.111-118
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• 2014

In mobile sensor networks, a large number of sensor nodes with battery powered are deployed randomly in a region. They monitor the environmental states and transmit data to its neighboring nodes. For mobile sensor networks, It is needed to maintain the connectivity autonomously among nodes as the sensor node moves. However, the existing works have focused on the energy savings in the fixed sensor networks. A specific algorithm considering node mobility is required in the mobile sensor networks. Along with energy efficiency, the transmission delay should be considered. In this paper, we propose an autonomous configuration scheme and a node scheduling algorithm when a moving node joins into the existing network. Through simulations, we show a superior performance of the proposed algorithm to the existing protocol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1C
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• pp.14-19
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• 2006

The high encoding complexity of LDPC codes can be solved by designing structured parity-check matrix. If the parity-check matrix of LDPC codes is composed of same type of blocks, decoder implementation can be simple, this structure allow structured decoding and required memory for storing the parity-check matrix can be reduced largely. In this parer, we propose a construction algorithm for short block length structured LDPC codes based on girth condition, PEG algorithm and variable node connectivity. The code designed by this algorithm shows similar performance to other codes without structured constraint in low SNR and better performance in high SNR than those by simulation

• 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.