• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.10
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• pp.908-917
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• 2013

In this paper, we propose a discovery protocol for finding nearby mobile applications and services in a device-to-device communications system. The device-to-device communication technology enables proximity-based services such as mobile social networks and mobile marketing. For realizing these proximity-based services, it is essential to design a discovery protocol which pinpoints the devices with mobile applications of interest among hundreds and thousands of devices in proximity. In the infrastructure-less networks such as ad hoc networks, we can design the discovery protocol that periodically broadcasts a short discovery code containing the compressed information of the mobile applications. In this paper, we design the discovery protocol with the discovery code generated by using a hash function and a Bloom filter. We also mathematically analyze the performance of the proposed protocol.

• Journal of Information Technology Services
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• v.14 no.3
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• pp.183-196
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• 2015

The concept of energy-efficient networking has begun to spread in the past few years, gaining increasing popularity. A common opinion among networking researchers is that the sole introduction of low consumption silicon technologies may not be enough to effectively curb energy requirements. Thus, for disruptively boosting the network energy efficiency, these hardware enhancements must be integrated with ad-hoc mechanisms that explicitly manage energy saving, by exploiting network-specific features. The IEEE 802.3az Energy Efficient Ethernet (EEE) standard is one of such efforts. EEE introduces a low power mode for the most common Ethernet physical layer standards and is expected to provide large energy savings. However, it has been shown that EEE may not achieve good energy efficiency because mode transition overheads can be significant, leading to almost full energy consumption even at low utilization levels. Coalescing techniques such as packet coalescing and interrupt coalescing were proposed to improve energy efficiency of EEE, but their implementations typically adopt a simple policy that employs a few fixed values for coalescing parameters, thus it is difficult to achieve optimal energy efficiency. The paper proposes adaptive interrupt coalescing (AIC) that adopts an optimal policy that could not only improve energy efficiency but support performance. AIC has been implemented at the sender side with the Intel 82579 network interface card (NIC) and e1000e Linux device driver. The experiments were performed at 100 M bps transfer rate and show that energy efficiency of AIC is improved in most cases despite performance consideration and in the best case can be improved up to 37% compared to that of conventional interrupt coalescing techniques.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.10
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• pp.977-985
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• 2012

Recently, many countries have been developing new protocols to improve the performance of tactical ad hoc networks for implementing NCW (Network Centric Warfare). Combat net radio (CNR) networks are the most important communication infra for the ground forces such as infantry of Army. U.S. Army had developed MIL-STD-188-220D that is the Interoperability Standard for DMTDs (Digital Messages Transfer Device Subsystems) for voice and data communication in CNR. MIL-STD-188-220D is a candidate for MAC protocol of TMMR which is next radio and has a few constraints to used in TMMR. NAD (Network Access Delay) defined in MIL-STD-188-220D needs time synchronization to avoid collision. However, it is difficult for time synchronization to fit in multi-hop environment. We suggest the enhanced DAP (Deterministic Adaptable Priority)-NAD to prevent conflicts and decrease delays in multi-hop CNR. Simulation results show that the proposed scheme improves the performance in multi-hop CNR networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2665-2670
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• 2015

VANET is ad-hoc network in which vehicles are treated as node and these nodes are communicating with each other as well as RSUs on the road. In VANET, scheduling is a very important issue as the request data are to be delivered to the recipient vehicle properly and accurately. It is also critical that any request data which is sent to the vehicle is received by it in the time period for which the vehicle will be in range of RSU. RSU picks the one with the highest priority to serve based on the scheduling scheme. In this paper, we propose a scheduling algorithm to select the one with the highest priority in RSU, in which an RSU can transfer the overload requests to other RSUs. We use the modified DBP scheme to calculate the priority of request data. Simulation results show that our scheme outperforms other scheduling schemes under various conditions.

• Journal of Korea Multimedia Society
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• v.12 no.8
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• pp.1099-1108
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• 2009

The study of IP address allocation in MANET can be categories into Stateful and Stateless. The one, special node monitors other nodes' IP address and allocates IF address. And the other, node generates IP address by itself. Nodes in MANET have mobility and restricted resource, so Stateless is more suitable than Stateful. But, in Stateless, node requires DAD process because of unique IP address allocation. And Dos attack can be happened in DAD precess. In this paper, we propose a security method on preventing DoS attack against DAD in MANET using one-way hash function. Since, Computation of one-way hash function is suitable for nodes' restricted resource character in MANET. And we evaluate performance using NS2 and compare with other security method which is CGA using signature.

• Journal of Digital Convergence
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• v.19 no.10
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• pp.163-173
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• 2021

The purpose of this study was to explore a support model for domestic ICT companies to advance into overseas markets suitable for the post-corona era along with the rapidly changing global economic situation. As a result of the analysis, first, by analyzing the internationalization cases of domestic ICT companies through the realization theory, in the COVID-19 situation, domestic ICT companies organically respond to crisis situations through ad hoc responses, use of international networks, use of external organizations, and resource-based practices. Through qualitative analysis, we were able to confirm that we are growing overseas while achieving our goals. In addition, strategies for domestic ICT companies to grow through internationalization were derived. Ultimately, it was interpreted as a part that required advancement of government policy according to the government's overseas expansion support system.

• Convergence Security Journal
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• v.18 no.5_1
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• pp.53-58
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• 2018

MANET transmits data by hop-by-hop method because it is composed of mobile nodes without support of any infrastructure. Its structure is very similar to a block chain. However, it is exposed to various threats such as data tampering or destruction by malicious nodes because of transmission method. So, ensuring the integrity of transmitted data is an important complement to MANET. In this paper, we propose a method to apply the block chain technique in order to protect the reliability value of the nodes consisting the network from malicious nodes. For this, hierarchical structure of a cluster type is used. Only cluster head stores the reliability information of the nodes in a block and then, this can be spread. In addition, we applied block generation difficulty automatic setting technique using the number of nodes selecting cluster head and the reliability of cluster head to prevent the spread of wrong blocks. This can prevent block generation and spread by malicious nodes. The superior performance of the proposed technique can be verified by comparing experiments with the SAODV technique.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.4
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• pp.75-87
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• 2010

Secure communication has been one of the main challenges in vehicular ad hoc networks(VANET) since broadcast messages from nearby vehicles contain life-critical information for drivers and passengers. So far various secure communication schemes have been proposed to secure the communication in VANET, and they satisfy most security requirements. However most of them need to put trust on roadside units(RSUs), which are usually deployed in unattended area and vulnerable to compromise. In this paper, we propose a secure communication scheme, which does not need to put trust on RSUs. And we adopt a grouping technique to averagely divide the huge burden in the server without jeopardizing the anonymity of users. Moreover we design a complete set of protocols to satisfy common security requirements with a relatively lower hardware requirement. At last, we evaluate the scheme with respect to security requirements, communication overhead, storage overhead and network performance.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.4
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• pp.105-114
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• 2009

Messages exchanged among vehicles must be authenticated in order to provide collision avoidance and cooperative driving services in VANET. However, digitally signing the messages can violate the privacy of users. Therefore, we require authentication systems that can provide conditional anonymity. Recently, Zhang et al. proposed conditionally anonymous authentication system for VANET using tamper-resistant hardware. In their system, vehicles can generate identity-based public keys by themselves and use them to sign messages. Moreover, they use batch verification to effectively verify signed messages. In this paper, we provide amelioration to Zhang et al.'s system in the following respects. First, we use a more efficient probabilistic signature scheme. Second, unlike Zhang et al., we use a security proven batch verification scheme. We also provide effective solutions for key revocation and anonymity revocation problems.

• Convergence Security Journal
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• v.20 no.5
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• pp.33-39
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• 2020

In MANET consisting of only mobile nodes, all nodes serve as routes. However, the dynamic topology due to frequent movement of nodes degrades routing performance and is also cause of many security vulnerabilities. Therefore, security must be applied to routing techniques that can influence the performance of MANET. In this paper, we propose a technique for efficiently responding to various routing attacks and safe data transmission through application of zone-key based security routing techniques. A zone-based network structure was used, and a management node that manages member nodes in each zone was used in the proposed technique. In addition, the damage from the attacking node was minimized by issuing a key to each node and applying this to a routing technique. The zone management node issues a key for encryption routing information and manages the issuance information. A member node that wants to transmit data encrypts routing in formation using a key issued from the zone management node, and then performs path discovery using this. The improved performance of the proposed technique was confirmed through a comparative experiment with the CBSR and ARNA technique, excellent performance was confirmed through experiments.