• Journal of KIISE:Information Networking
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• v.30 no.2
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• pp.252-259
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• 2003

In the case of link congestion, most of the existing ad-hoc routing protocols like AODV and DSR do not try to discover a new route if there is no change in the network topology. Hence, with low mobility, traffic may get concentrated on some specific nodes. Since mobile devices have low battery power and low computing capability, traffic concentration on a specific node is not a desirable phenomenon. Therefore, in this paper, we propose a new protocol called SLAP (Simple Load-balancing Ad-hoc routing Protocol) which resolves the traffic concentration problem by letting each node check its own load situation and give up its role as a packet forwarder gracefully in the case of high traffic load. We compare the performance of SLAP with that of AODV and DSR in terms of the forwarding traffic distribution.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.2
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• pp.189-197
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• 2016

Mobile ad-hoc networks (MANETs) experience frequent link disconnections due to non-uniform node distribution and mobility. Thus, end-to-end path establishment-based routing protocols cause frequent transmission failures in MANETs, resulting in heavy control messages for path reestablishment. While location-based MANET routing protocols, such as Greedy Perimeter Stateless Routing (GPSR), use location information to forward messages in a hop-by-hop routing fashion without an end-to-end path establishment procedure, such protocols encounter communication void problems when message forwarding to the next hop fails due to the absence of a relay node. Therefore, to solve this problem, this paper proposes a Delay Tolerant-GPSR (DT-GPSR) protocol, which combines Delay Tolerant Networking (DTN) technology with the GPSR protocol. The performance of DT-GPSR is compared with the performances of the original GPSR and PRoPHET routing protocols through simulation using NS-2. The simulation results confirm that DT-GPSR outperforms GPSR and PRoPHET in terms of the message delivery ratio and message delivery delay.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.2
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• pp.10-16
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• 2016

For higher reliability against a link failure of a control network in railway vehicles, a recovery mechanism is needed. We introduce a problem that, when a link failure occurs in a ring-topology control network, a node may experience a significant increase of transmission delay depending on its relative position within the network. We then propose two mechanisms to solve this problem: (1) differentiating and prioritizing node traffic in forwarding; and (2) switching some nodes to a backup bus-topology network. Our simulation study shows that, while the first mechanism achieves a limited gain by only compensating queuing delay, the second one gets a sufficient gain which is impacted by the number of nodes switched to the bus network.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.5
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• pp.83-91
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• 2008

IISO/IEC 9594-8 defines the public key framework and attribute certificate framework. Attribute certificate framework deals with privilege management infrastructure(PMI). In PMI, for privilege management using attribute certificates, role assignment certificates and role specification certificates are used to assign and specify privileges independently. Role specification certificates includes privilege specifications and the details far privilege management of network environments. Privilege management of unreliable network environment tries to enhance the reliability and efficiency of privilege information transmission forwarding over unreliable routes in the presence of potentially faulty nodes and edges. Each node forms a role specification tree based on role specification relationship data collected from the network. In this paper privilege management cost with the role specification certificates tree structure is evaluated trying to reduce the overhead incurred by role creation and modification of privileges. The multicasting of packets are used for scalability. We establish management cost model taking into account the packet loss and node reliability which continuously join and leave for network. We present quantitative results which demonstrate the effectiveness of the proposed privilege management scheme.

• Journal of the Korea Society of Computer and Information
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• v.27 no.9
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• pp.113-120
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• 2022

In this paper, we analyze the feasibility of the IP spoofing attack exploiting null security algorithms in 5G networks based on 3GPP standard specifications. According to 3GPP standard specifications, the initial Registration Request message is not protected by encryption and integrity. The IP spoofing attack exploits the vulnerability that allows a malicious gNB (next generation Node B) to modify the contents of the initial Registration Request message of a victim UE (User Equipment) before forwarding it to AMF (Access and Mobility Management Function). If the attack succeeds, the victim UE is disconnected from the 5G network and a malicious UE gets Internet services, while the 5G operator will charge the victim UE. In this paper, we analyze the feasibility of the IP spoofing attack by analyzing whether each signaling message composing the attack conforms to the 3GPP Rel-17 standard specifications. As a result of the analysis, it is determined that the IP spoofing attack is not feasible in the 5G system implemented according to the 3GPP Rel-17 standard specifications.

• Journal of IKEEE
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• v.23 no.1
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• pp.280-288
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• 2019

In the CR-enabled MANET, routing paths can be easily destroyed due to node mobility and channel unavailability (due to the emergence of the PU of a channel), resulting in significant overhead to maintain/recover the routing path. In this paper, network caching is actively used for route maintenance, taking into account the properties of the CR. In the proposed scheme, even if a node detects that a path becomes unavailable, it does not generate control messages to establish an alternative path. Instead, the node stores the packets in its local cache and 1) waits for a certain amount of time for the PU to disappear; 2) waits for a little longer while overhearing messages from other flow; 3) after that, the node applies local route recovery process or delay tolerant forwarding strategy. According to the simulation study using the OPNET simulator, it is shown that the proposed scheme successfully reduces the amount of control messages for path recovery and the service latency for the time-sensitive traffic by 13.8% and 45.4%, respectively, compared to the existing scheme. Nevertheless, the delivery ratio of the time-insensitive traffic is improved 14.5% in the proposed scheme.

• Journal of Digital Convergence
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• v.10 no.9
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• pp.319-324
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• 2012

Vehicle safety communications is one among the important technologies in order to protect a car accident. For this, many protocols forwarding a safe message have studied to protect a chain-reaction collision when a car accident occurs. most of these protocols assume that the time of generating a safe message is the same as an accident's. If a node predicts some traffic hazard and forwards a safe message, a driver can response some action quickly. So, In this paper, we proposes a traffic hazard prediction algorithm using the communication technique. As a result, we show that the frame reception success rate of using our algorithm to the previous protocol improved about 4~5%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.2
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• pp.577-594
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• 2020

Service Function Chaining (SFC) supports services through linking an ordered list of functions. There may be multiple instances of the same function, which provides a challenge to select available instances for all the functions in an SFC and generate a specific Service Function Path (SFP). Aiming to solve the problem of SFP selection, we propose an architecture consisting of distributed SFP algorithm and central control mechanism. Nodes generate distributed routings based on the first function and destination node in each service request. Controller supervises all of the distributed routing tables and modifies paths as required. The architecture is scalable, robust and quickly reacts to failures because of distributed routings. Besides, it enables centralized and direct control of the forwarding behavior with the help of central control mechanism. Simulation results show that distributed routing tables can generate efficient SFP and the average cost is acceptable. Compared with other algorithms, our design has a good performance on average cost of paths and load balancing, and the response delay to service requests is much lower.

• Journal of Korea Multimedia Society
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• v.10 no.1
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• pp.94-101
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• 2007

Partial dominant pruning(PDP) is regarded as the most practical scheme, reducing redundant messages arisen in broadcasting over ad hoc networks, in such a way that only part of nodes are allowed to forward the received broadcast message. In this paper we propose an extend PDP version called DPDP(directional PDP) such that it reduces not only the number of selected forward nodes, but also the number of antenna elements deployed by the forward nodes. It turns out through simulation that as the number of antenna elements increases, the number of selected forward nodes by DPDP slightly outnumbers that obtained using PDP but both the number of antenna elements deployed by the forward nodes and the redundancy ratio of the received message per node always outperform respectively those given by PDP.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.163-166
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• 2003

In recent years, there has been increased to access multimedia service through the Internet due to rise of the access speed. We suppose the co-existence of the various access networks in adjacent area in the future, such as wireless LAN, Bluetooth, and 3G Cellular So, the size of the cell will be smaller and the number of access point will be increased. In other words, the potable devices need the efficient mobility scheme due to move between cells frequently Currently, the several of the scheme, which is Cellular IP, HAWAII, Mobile IPv4 regional registration, and hierarchical Mobile IPv6, is suggested to support micro-mobility but Mobile IPv4 is standard scheme to support the mobility of the mobile node. MPLS, which forwards the packet through switching instead of routing using IP address, has begun to deploy in the internet backbone to increase the performance of mobility protocol. The integration of both MPLS and Mobile IP improves the scalability of the Mobile IP data forwarding process by leveraging on the features MPLS which are fast switching and high scalability. Moreover it abbreviates IP-in-IP tunneling between HA and FA. In this paper, we suggest efficient mobility scheme through integration of both MPLS and hierarchical Mobile IPv6.