• Journal of the Korean Association of Geographic Information Studies
• /
• v.7 no.2
• /
• pp.29-36
• /
• 2004

The purpose of this study is to analyze DMB(digital multimedia broadcasting) technologies of transmitting GIS-based traffic information for developing DMB systems compared with FM DARC(FM data radio channel). R&D and standardizations for transmitting GIS-based traffic information have been rapidly changed, as radical developments in ITS(intelligent transportation systems), telemaics, and communication methods such as ubiquitous and convergences of broadcasting and communications. Each communication method employs different GIS format, protocol, and standardizations, i.e., GML(geography markup language) and TPEG(transport protocol experts group). This paper presents technical methods and trends of transmitting traffic information using broadcasting along with FM DARC, in general, and DMB, in particular.

• Journal of the Korea Convergence Society
• /
• v.5 no.3
• /
• pp.1-5
• /
• 2014

The development of communication method for a variety of intelligent automobiles are delivering comfortable and safe information. However the development of such communication method must also think about security. Even the update of navigation to be used for intelligent automobiles uses the wireless updating methods but the updating methods currently being used has no reliable security measures. The navigation communications used in the intelligent automobiles are being provided with TTI(Traffic and Travel Information) service using a variety of methods by the countries. In the case of Korea, most are based on T-DMB using the TPEG method for transmitting the information. By identifying the characteristics on the navigation wireless update, a security solution is proposed for delivering the reliable update information after creating the attack scenario.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.5B
• /
• pp.463-468
• /
• 2009

In VANET(Vheicle Ad hoc Network), the researches based on the wireless LAN are conducting and the method based on 802.11a is being adapted in IEEE 802.11p WAVE(Wireless Access in Vehicular Environments). However, wireless LAN which uses a single channel in a competition can cause transmission delays because of a frequent collision and a use of CSMA/CA to avoid competition in VANET requiring a fast access. In this paper, we designed CMMP (Clustering based Multi-channel MAC protocol) adequate to VANET and then confirmed the appropriate channel conditions in a V2V communication on the basis of this protocol. The simulation results showed that a packet collision and a transmission delay by the use of an existing single channel based on the contention decreased more than 60% by CMMP.

• Journal of the Korea Society of Computer and Information
• /
• v.14 no.11
• /
• pp.105-111
• /
• 2009

The study aims to propose the intelligent clustering technique that calculates the distance by improving the problems of multi-hop clustering technique for inter-vehicular secure communications. After calculating the distance between vehicles with no connection for rapid transit and clustering it, the connection between nodes is created through a set distance vale. Header is selected by the distance value between nodes that become the identical members, and the information within a group is transmitted to the member nodes. After selecting the header, when the header is separated due to its mobility, the urgent situation may occur. At this time, the information transfer is prepared to select the new cluster header and transmit it through using the intelligent cluster provided from node by the execution of programs included in packet. The study proposes the cluster technique of the intelligent distance estimation for the mobile Ad-hoc network that calculates the cluster with the Store-Compute-Forward method that adds computing ability to the existing Store-and-Forward routing scheme. The cluster technique of intelligent distance estimation for the mobile Ad-hoc network suggested in the study is the active and intelligent multi-hop cluster routing protocol to make secure communications.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.10
• /
• pp.42-51
• /
• 1998

This paper suggests a congestion control scheme for CL (ConnectionLess) overlay network using the feedback loops between CL user and CL server, between CL servers, and between end-to-end CL users, and the header translation table of CL server. The CL overlay network for CBDS(Connectionless Broadhand Data Service) defined by ITU-T((International Telecommunication Union-Telecommunication) consists of CL servers which route frames and links which connect between CL user and CL server or between CL servers. In the CL overlay network, two kinds of congestion, CL link congestion and CL server congestion, may occur. We considered the schemes to solve the congestion. link-by-link method[18] has used the ABR feedback loops of ATM layer between CL user and CL server or between CL servers, and the congestion table using header translation table of CL server. As in congestion of output virtual channel this method has an effect on all the traffic transmitting through the link, then it has an effect on the traffic that has not caused the congestion. As a result, the link utilization of output virtual channel that does not bring the congestion and outputs the traffic is decreased. To overcome this drawback of link-by-link, we proposed the hybrid method that are using the ABR feedback loops of link-by-link method, the feedback loop between CL users in end-to-end, the congestion table using and the header translation table. This scheme deals with teh congestion immediately by link-by-link loops and the header translation table, and then regulates the sending rate of CL user that causes the congestion by end-to-end loop.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.1
• /
• pp.96-107
• /
• 2015

VANET technologies provide real-time traffic information for mitigating traffic jam and preventing traffic accidents, as well as in-vehicle infotainment service through Telematics/Intelligent Transportation System (ITS). Due to the rapid increasement of various requirements, the vehicle communication with a limited resource and the fixed frame architecture of the conventional techniques is limited to provide an efficient communication service. Therefore, a new flexible operation depending on the surrounding situation information is required that needs an adaptive design of the network architecture and protocol for efficiently predicting, distributing and sharing the context-aware information. In this paper, Vehicle-to-Infrastructure (V2I) based on communication between vehicle and a Road Side Units (RSU) and Vehicle-to-Vehicle (V2V) based on communication between vehicles are effectively combined in a new MAC architecture and V2I and V2V vehicles collaborate in management. As a result, many vehicles and RSU can use more efficiently the resource and send data rapidly. The simulation results show that the proposed method can achieve high resource utilization in accordance. Also we can find out the optimal transmission relay time and 2nd relay vehicle selection probability value to spread out V2V/V2I collaborative schedule message rapidly.