• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5B
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• pp.455-462
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• 2009

In this paper, we propose a buffer management scheme for decreasing the packet loss due to buffer overflow and improving the packet fairness between nodes in IEEE 802.11 based multi-hop mesh networks. In the proposed scheme, each mesh router that is an intermediate node receives fairly packet sent from neighboring mesh routers and mobile nodes, and it improves the reception ratio of multi-hop traffic of neighboring mesh routers. Therefore, the proposed scheme can reduce transmission delay and energy consumption. In order to improving the packet loss and the packet fairness, the proposed scheme uses the modified RTS/CTS under the IEEE 802.11 MAC protocol and reduces the packet loss by recognizing the packet size to send to the destination in advance. By using the simulation, we evaluated the proposed scheme in terms of the packet loss ratio and the number of received packet in each mesh router, and compare it to a traditional scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8B
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• pp.1115-1121
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• 2010

The DNAv6 was designed to support fast attachment for a host, which is corresponding to the movement detection part in the mobility management. Since, however, the DNAv6 has supported only DNAv6-capable ARs and DNAv6-capable hosts, an non-DNAv6 host could not support fast handoff function in a DNAv6 network. In this paper, we consider a new method of the fast attachment of non-DNAv6 hosts. To support the non-DNAv6 host in DNAv6 networks, we suggest a novel algorithm, RCA algorithm, where an AR can decide whether a host has the DNAv6 function and whether it has moved to a new link or not, and then the AR can inform the host of new link information. For the RCA algorithm, we proposed to modify the RS message and the Reconf_Link message with addition of some fields. To validate our RCA algorithm and its performance, we have accomplished simulation tests for the ND process, the DNAv6 process and the modified DNAv6 process with our RCA algorithm. In the viewpoints of the attachment delay and complexity, the proposed algorithm gives the better delay performance than the ND process while it presents the less complexity than the DNAv6 process.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.9
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• pp.620-628
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• 2014

Various on-demand manner routing protocols have been proposed for efficient energy consumption in mobile ad-hoc networks. Some of the protocols tried to extend the network lifetime by periodically rerouting paths according to the energy consumption rate of nodes. However, those protocols suffer from frequent flooding and high overhead. This paper proposed a new routing protocol called ALPMR (Adaptive Local Path Modification Routing) that extends the network lifetime by using local path rerouting. The proposed ALPMR protocol performs local rerouting around nodes with little remaining energy as well as data congestion, thus reduces flooding and routing overhead and can extend the network lifetime. The performance of ALPMR protocol is observed using ns-2 simulator.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.3
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• pp.143-150
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• 2014

In this paper, we propose an energy efficient and delay guaranteed node scheduling scheme inspired by biological systems, which have gained considerable attention as a computing and problem solving technique. With the identification of analogies between cellular signaling systems and WSN systems, we formulate a new mathematical model that considers the networking challenges of WSNs. The proposed bio-inspired algorithm determines the state of the sensor node, as required by each application and as determined by the local environmental conditions and the states of the adjacent nodes. A control analysis shows that the proposed bio-inspired scheme guarantees the system stability by controlling the parameters of each node. Simulation results also indicate that the proposed scheme provides significant energy savings, as well as reliable delay guarantees by controlling the states of the sensor nodes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.11
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• pp.1185-1191
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• 2014

An integrated ship area network has functionality of remote control and autonomous management of various sensors and instruments embedded or boarded in a ship. For such environment, a wireless bridge is essential to transmit control and/or managing information to sensors or instruments from a central integrated ship area network station. In this paper, one of reliable schemes of In-ship sensor networks using a Grid-based WPAN is proposed. The proposed scheme is based on a novel grid network which allows a multi-path communication, and is robust, energy efficient. The results demonstrate that the proposed Grid-based WPAN outperforms the IEEE 802.15.4 based network in terms of success ratio and power efficiency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.296-304
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• 2010

MoIP is technology to transmit a variety of multimedia over IP, but compared to traditional voice services require greater bandwidth and radio resources in a wireless environment has already reached the limits. Therefore, as a way to resolve this issue for header compression is a lot of research. SCTP protocol header compression using ROHC-SCTP has been research, ROHC-SCTP packet structure of the ROHC algorithm with different types and, SCTP header compression to apply the characteristics of the poor performance of many of these have drawbacks. Therefore, in this paper to solve these problems better header compression algorithm was designed. In this paper, the proposed algorithm to evaluate the NS-2 simulation environment was modeled on the header compression operation. Evaluation results, the algorithm designed in this paper compared to ROHC-SCTP algorithms determine the overhead rate was low, the data types vary a lot better when the total header size was small.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12B
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• pp.2249-2261
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• 1999

In this paper, we describe the design and implementation of the Label Distribution Protocol (LDP) for Multiprotocol Label Switching System. We review the implementation issues of LDP that is required to make a gigabit switched router, and propose a detail design of it. We present the data structures and procedures for the LDP as a result, which are based on IETF standard. We present design issues for applying this to carrier class products. The implemented protocol could afford 40,000 entries of the IP routing table that is required for deploying this system to commercialized data network. Furthermore this system implemented using the standard API of Unix, as a result, it has portability. By implementing LDP based on the international standard and these implementation issues, we expect that the implemented LDP will be interoperable with other commercialized products. We prove the validity of the design of the LDP through prototyping, and also verify the prototype with the specification using the process algebra and the performance analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1B
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• pp.8-15
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• 2008

Cognitive radio technology enables to share the spectrum dedicated to primary users. In CR network, it is of primary concern to protect the primary users. Thus, it is required to periodically sense the spectrums occupied by primary users and adapt the communication parameters used by CR users to protect the primary users. However, it is inevitable to experience the hidden node problem due to the primary users, that are not detected by spectrum sensing. To perfectly protect the primary users, it is essential to address the hidden node problem in CR network. In this paper, we propose a new approach to handle the hidden node problem and evaluate the performance of proposed scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1A
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• pp.57-65
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• 2007

The overlay multicast that has been recently presented as IP alternative for the IP multicast has been getting much persuasion by the computing power of the hardware and the advancement of the network techniques to enforce Routing in application-level. In an overlay multicast, the system resource and the network bandwidth must be utilized efficiently to service real-time HDTV images. Specifically, the system must consider the delay and the jitter that can be incurred at the application-level. In this paper, we implement a server and a client to broadcast HDTV, in the session composed by the existing overlay multicast protocol. The broadcasting server performs the service using a TV tuner, An HDTV camcorder, and files, clients constituting a multicast group relay the received data to other clients. At this time, the information that the clients report periodically, including their delay and the network state, to the server is used as an important information to maintain an overlay session. The implementation is based on the DirectX and its performance is evaluated by the LAN test bed that has been set.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.9
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• pp.707-714
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• 2013

IoT, which can be regarded as an enhanced version of M2M communication technology, was proposed to realize intelligent thing to thing communications by utilizing Internet connectivity. Things in IoT are generally heterogeneous and resource constrained. Also such things are connected with each other over LLN(low power and lossy Network). Confidentiality, mutual authentication and message origin authentication are required to make a secure service in IoT. Security protocols used in traditional IP Networks cannot be directly adopted to resource constrained devices in IoT. Under the respect, a IETF standard group proposes to use lightweight version of DTLS protocol for supporting security services in IoT environments. However, the protocol can not cover up all of very constrained devices. To solve the problem, we propose a scheme which tends to support mutual authentication and session key agreement between devices that contain only a single crypto primitive module such as hash function or cipher function because of resource constrained property. The proposed scheme enhances performance by pre-computing a session key and is able to defend various attacks.