• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.17 no.6
• /
• pp.202-210
• /
• 2018

Recently, the subway running in metro environments has a problem in securing the safety of passengers due to the failure of announcement in emergency situations such as breakdown, train accidents and power outage in the underground tunnels. Thus, there is a need to develop an emergency broadcasting system that can provide the announcement to all passenger cars in any emergency situations on the railway route. In this paper, the applicability of various wireless communication technologies for the emergency broadcasting system through the measurement campaign was examined in Seoul metropolitan subway. A WAVE(Wireless Access in Vehicular Environments) is communication technology that can use 5.9GHz dedicated frequency band without charge and it is possible to directly communicate between terminals over 200m without the help of additional relay. Especially, it confirms robust communication performance in the various metro environments, and therefore, it is considered to be suitable as a communication method of a radio-connected emergency broadcasting system for urban subway.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.17 no.4
• /
• pp.587-594
• /
• 2022

This paper analyzed radio link throughput performance by applying radio link simulation and test equipment because there is limit in train filed test in 420 km/h high speed environment. According to the radio performance analysis, the throughput performance is slightly degraded in QPSK and 16QAM modulation schemes. But throughput performance is highly degraded in 64QAM modulation scheme.

• Proceedings of the KSR Conference
• /
• 2006.11b
• /
• pp.1454-1460
• /
• 2006

This paper assesses communication performance using a roaming simulator when roaming occurs between onboard and ground wireless communication devices for communication based train control system (CBTC). Generally, CBTC is defined as the system regularly collecting location and speed data from each train, transmitting distance information to a train, and optimizing train speed according to train performance. When a train is moving, roaming is also performed to continuously transmit and receive train control information between the ground controller and the train. To operate CBTC, packet loss rate should be less than 1%, roaming time less than 100ms during roaming. We developed a roaming simulator to check communication performance before installing ground and onboard equipments on actual wireless sections. The roaming simulator to be introduced in this paper is for roaming simulation before conducting CBTC field test, which is the project to develop Urban Rail Signaling System Standards, being conducted in KRRI. The simulation consists of one onboard wireless communication device and three ground wireless communication devices, and the roaming simulator estimate packet loss rate occurring during roaming process of the two devices. Therefore, if you use the roaming simulator before the field test, you can predict various problems to occur in actual environment and reduce time, cost and people necessary to resolve these problems.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.7 no.1
• /
• pp.149-156
• /
• 2012

This paper suggests the data transmission technology for applying to the actual railway line based on the technological trends and theories for the wireless Mesh techniques. This paper presents a technical basis that is applicable to the economic and efficient use of frequency and to the development of a Communication Based Train Control System by demonstrating its Applicability, Availability, Reliability and Safety for the train control system of the radio frequency of the bandwidth of 5.7 GHz at the experiments.

• Journal of the Korean Society for Railway
• /
• v.10 no.5
• /
• pp.589-595
• /
• 2007

Korea Railroad Research Institute has developed the driverless rubber-tired K-AGT (Korean-Automated Guideway Transit) system from 1999 to 2005 and has done its performance and reliability tests on the test line at Gyeongsan-city. Radio Frequency Communication-Based Train Control system of K-AGT, which employed Advanced Automated Train Control scheme, detects train position using the radio propagation delay between wayside and vehicle radio equipment. In this paper, we investigate whether the transmission power of radio system can be reduced to the permitted level announced by the Ministry of Information and Communication for license-free ISM(Industrial Scientific Medical) frequency bands. We first determine radio propagation model, using the measured data at test line, and perform simulation for radio coverage prediction. From the simulation results, we identify that the radio system operated with reduced power can provide good link quality in total test line.

• Journal of the Korean Society for Railway
• /
• v.19 no.6
• /
• pp.736-743
• /
• 2016

In accordance with the trend of higher speed and automation, the Train Control System is building on the technology of control methods using radio in the technology of exchanging information by wire, toward a wireless communication method that will be applied using LTE-R radio communication technology with $4^{th}$ generation LTE mobile communication a $2^{nd}$ generation GSM-R. Therefore, a standard specification suitable for the Korea Radio based Train Control System-2(below KRTCS-2) for the 350km/h class using wireless communication is created; a prototype based on the standard specification is installed on a high-speed train and is installed on a test section(Ik san-Jeong eup) on the Honam high speed line to ensure the reliability and safety of the standard specifications, which are verified through various performance tests. In the future, the standard specification that has been established as a national railway standard, and the standard specifications will be commercialized by applying the train control system to conventional and High speed railway lines.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.12 no.1
• /
• pp.69-74
• /
• 2017

Due to the advantage of communication coverage extension and removement of shadowing area, relay can be applied in various wireless communication systems. In this paper, we analyze performance of downlink with dual-hop communication systems which use a relay in railway environments. We adopted asymmetric communication system which use coherent modulation scheme in base station-relay link and differential modulation scheme in relay-destination link. The performance of communication system is analyzed using symbol error rate, and performance comparison with the systems which adopts fully coherent scheme is studied. We also investigate the performance of system depending on relay distance and energy allocation.

• Proceedings of the KIEE Conference
• /
• 2001.04a
• /
• pp.439-442
• /
• 2001

선로상에 열차의 은행에 지장을 주는 장애물들 검지하였을 때 반대편 열차에 알리거나 열차내의 긴급한 상황이 발생하였을 경우에 대비하여 열차와 지상의 사령과는 항상 열차무선을 통하여 정보를 교환한다. 초창기에 사용하는 열차무선시스템은 열차의 운행빈도나 사용자의 측면에서 아날로그방식의 음성통화로 충분한 서비스를 제공할 수 있었으나, 근래에는 고밀도의 열차운행 및 고속화로 다수의 사용자가 요구하는 서비스를 충족하기에는 많은 개량할 부분을 가지고 있다. 통신기술의 발전과 더불어 한국의 고속철도에서 사용예정인 열차무선시스템은 이러한 사용자들의 요구를 충족하기 위해 통신망의 개념을 도입하고 디지털의 TRS 시스템을 이용하여 많은 사용자의 요구를 충족하려고 노력하고 있다. 또한, 유럽에서 여러 국가를 횡단하는 고속열차의 경우 열차무선시스템에서 횡단하는 국가들간의 호환성을 극복해야하는 문제 등을 가지고 있다. 본 연구에서는 기존 VHF방식의 개량할 점과 TRS시스템의 특징 및 유럽에서 사용중인 열차무선시스템의 운영방법 등을 통하여 열차무선의 발전방향을 제시하고자한다.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.10 no.8
• /
• pp.953-958
• /
• 2015

Generally, Urban railway have special characteristics with short distance journey and minimum headway intercity transportation. These days, urban railway operators choose the driverless operation system without driver. On the contrary, Conventional & high speed railway utilize for long distance and high speed running. Because of special conditions of freight railway operation compared with urban railway, operation of conventional & high speed railway is showed very different characteristics. In this paper, We compares different operation scheme of urban railway and conventional & high speed railway and then present condition for train control system based on radio.

• Journal of the Korean Society for Railway
• /
• v.15 no.1
• /
• pp.29-36
• /
• 2012

This paper includes ATP(Automatic Train Protection) simulator development and ATP algorithm verification to allocate wayside and train-borne and verify ATP functions of communications based train control system. The train control system has some characteristics such as simple structure and high safety when wireless communication technology is applied to the train control system. Especially, vital functions can be performed with in wayside and train-borne ATP. However, different system can be realized because I/F contents vary in accordance with vital functional allocation of ATP. Drawing characteristics in accordance with wayside and train-borne functional allocation and drawing I/F details affected by such characteristics are needed accordingly. This paper includes ATP simulator development creating train location information by direct activation of an electric motor, verifies train safety distance control algorithm of ATP by functional allocation such as train movement authority and train speed limit to ATP, and draws any supplementation needed. Appropriate simulated environment for verify ATP algorithm and main factors that affect to the ATP function were confirmed.