• Journal of Communications and Networks
• /
• v.16 no.3
• /
• pp.311-321
• /
• 2014

This paper focuses on contention-based medium access control (MAC) protocols used in wireless local area networks. We propose a novel MAC protocol called adaptive backoff tuning MAC (ABTMAC) based on IEEE 802.11 distributed coordination function (DCF). In our proposed MAC protocol, we utilize a fixed transmission attempt rate and each node dynamically adjusts its backoff window size considering the current network status. We determined the appropriate transmission attempt rate for both cases where the request-to-send/clear-to-send mechanism was and was not employed. Robustness against performance degradation caused by the difference between desired and actual values of the attempt rate parameter is considered when setting it. The performance of the protocol is evaluated analytically and through simulations. These results indicate that a wireless network utilizing ABTMAC performs better than one using IEEE 802.11 DCF.

• The KIPS Transactions:PartC
• /
• v.14C no.5
• /
• pp.453-462
• /
• 2007

NGN is a packet-based converged network to support session and non-session based services in QoS-enabled broadband transport technologies. Resource and admission control functions(RACF) of NGN have been considering COPS and SNMP as resource management protocols to collect network topology and resource status information of transport network. This paper defines requirements of resource management in NGN transport network, and proposes protocol independent information model to keep consistency of data models of each resource management protocol. Based on this information model described with UML class diagram, we designed and implemented NGN resource management system on Web Services.

• Journal of the Semiconductor & Display Technology
• /
• v.14 no.2
• /
• pp.17-22
• /
• 2015

In recent years, wireless sensor networks have become an important part of data communications. Sensors provide information about the required measurements or control states over wireless networks. The energy efficient routing protocol of wireless sensor networks is the key issue for network lifetimes. The routing protocol must ensure that connectivity in a network is remained for a long period of time and the energy status of the sensor in the entire network must be in the same level in order not to leave the network with a wide difference in the energy consumptions of the sensors. In this paper we propose a new routing protocol based on AODV protocol that considers the energy efficiency when the protocol determines the routing paths, which is called AODV-EE. The proposed method prevents an imbalance of power consumption in sensors of wireless networks. From the simulation results it is shown that the proposed algorithm can be effectively used in collecting and monitoring data without concerning about the disconnection of the networks.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.7 no.5
• /
• pp.925-933
• /
• 2003

Network is expected to be developed into optical Internet network collected IP layer and optical layer, but GMPLS is risen at the transitional evolution stage because of the present technology level. GMPLS that MPLS is extended and generalized is able to support not only the packet switching device but also the devices which perform switching in time, wavelength, and space domain. To implement the common control plane to these various switching types, GMPLS extends the existing MPLS signaling and routing protocol. In this paper, we describe the overview of GMPLS technology, and then we will refer to the OSPF(Open Shortest Path First), which was used to exchange the status information of link, as the plan of routing extension to exchange the information of various link type, bandwidth, link protection type etc. And also, we describe the definition of new protocol, so called, LMP that is a signaling protocol for solving complex problem which manages hundreds and thousands of links between two nodes. And we will examine and analyze the plan of signaling protocol extension to apply signaling protocol RSVP-TE(Resource Reservation Protocol) for traffic engineering in MPLS to network, and the message objects and formats associated with modified RSVP.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.3
• /
• pp.541-548
• /
• 2012

On this paper, we proposed a design rule of charger monitoring system which allow us to watch the charging status and verify it for building the electric chargers infrastructure by spread of electric vehicle. Gathering the charging status of battery by proposed system makes us to enhance the charging algorithm, to interface with BMS(Battery Management System) of electric vehicle, to control the charging process with users. Because the technology of rapid charging is dependant upon various factors such as a performance and stability of battery. We proposed the monitoring system of rapid charger based on CAN protocol that can watch a working status of rapid charger including the charging status of battery with real time and can reduce the charging time of battery with optimized status. We also implement it and evaluate its performance.

• Proceedings of the IEEK Conference
• /
• 2004.08c
• /
• pp.552-557
• /
• 2004

Mobile Ad Hoc Network (MANET) is a network architecture, which has no backbone network and is deployed temporarily and rapidly in emergency or war without fixed mobile infrastructures. All communications between network entities are carried in ad-hoc networks over the wireless medium. Due to the radio communications being extremely vulnerable to propagation impairments, connectivity between network nodes is not guaranteed. Therefore, previously developed routing algorithms in wired networks cannot be used. And many new algorithms have been undergone. This study proposes the secondary leader approach to the cluster based routing protocol(CBRP). In case, the primary leader becomes abnormal status so that the primary leader cannot participate the communications between network entities, the secondary leader immediately replaces the primary header without selecting process of the new primary leader. The performances of proposed algorithm ACBRP(Advanced Cluster. Based Routing Protocol;CBRP using secondary leader) are compared with CBRP and results are presented in order to show the effectiveness of the algorithm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2007.06a
• /
• pp.823-826
• /
• 2007

In ubiquitous environment, mobile devices, which users carry, tend to be resource-constraint, thus resulting in the need for an authentication protocol, which provides light-weight computations as well as strong security. Recently S/Key based protocols, which satisfy such a requirement by achieving light-weight computations, strong authentication and session key exchange, have been proposed. In particular, You and Jung's protocol is more efficient and secure than others. In this paper, we compare and analyze You-Jung with other protocols. Also, we design an authentication scenario and status of mobile devices while implementing the protocol.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.7
• /
• pp.1357-1362
• /
• 2009

The multimedia contents are diffused rapidly. Also, the course individual service of communication and broadcasting coexists with each other and develop to the integrated fusion service with development of the high speed broadband IP network technology. The IPTV which is representative broadcasting a communication total service is the powerful application field. The communication industry has been interested in data processing of the high-definition that supports many kinds of internet service by internet protocol. In this paper, we configure the standard routing protocol use in the small scaled, on RIP environment and the link status routing protocol use the large scale autonomous network, on OSPF environment. We also measure and evaluate broadcasting quality by PSNR(Peak Signal-to-Noise Ratio). Finally, we propose the network construction plan for IPTV services which are efficient.

• The KIPS Transactions:PartC
• /
• v.11C no.3
• /
• pp.371-378
• /
• 2004

SIP(Session Initiation Protocol) is a text based call signaling protocol that has characteristics such as flexibilities and extensibility for various application services over Internet. In this paper, we have implemented SIP based integrated Instant Messenger system which includes Presence Watcher Information service that can notify various current users status. In this system, voice and video communications are also possible as well as text based instant messages. For voice and video communication, we have newly proposed a method in which direct connection is possible between users without creation of SW INVITE dialog by extending PRESENCE TUPLE of presence information. In this case, PRESENCE TUPLE stores some informations necessary for the session.

• Journal of Information Processing Systems
• /
• v.7 no.1
• /
• pp.53-62
• /
• 2011

With the steady growth of mobile technology and applications, demand for more storage in mobile devices has also increased. A lightweight block-level protocol, Internet Advanced Technology Attachment (iATA), has been developed to deliver a cost-effective storage network solution for mobile devices to obtain more storage. This paper seeks to contribute to designing and implementing Load Balancing (LB), Network Monitoring (NM) and Write Replication (WR) modules to improve the protocol's scalability and data availability. LB and NM modules are invoked to collect system resources states and current network status at each associate node (server machine). A dynamic weight factor is calculated based on the collected information and sent to a referral server. The referral server is responsible to analyze and allocate the most ideal node with the least weight to serve the client. With this approach, the client can avoid connecting to a heavily loaded node that may cause delays in subsequent in-band I/O operations. Write replication is applied to the remaining nodes through a WR module by utilizing the Unison file synchronization program. A client initially connected to node IP A for write operations will have no hindrances in executing the relevant read operations at node IP B in new connections. In the worst case scenario of a node crashing, data remain recoverable from other functioning nodes. We have conducted several benchmark tests and our results are evaluated and verified in a later section.