Definition
Introduction
The frequency band of China Railway is 885-889MHz in the uplink direction and 930-934MHz in the downlink direction. The GSM-R system includes four parts: Network Subsystem (NSS), Base Station Subsystem (BSS), Operation and Service Support Subsystem (OSS/BSS), and terminal equipment. Among them, the network subsystem includes the mobile switching subsystem (SSS), the mobile intelligent network (IN) subsystem, and the general packet radio service (GPRS) subsystem. The GSM-R system adopts the master-slave synchronization method. Devices such as TMSC, MSC, HLR, SCP, etc. should obtain timing signals from nearby BITS devices. The G digital link between MSC and BSS should also be used as a synchronization link. BSS obtains synchronization from MSC. The clock signal can also be extracted from the nearby BITS device or SDH device to synchronize the clock signal. The GSM-R transmission system refers to the digital transmission system that provides channels for the connection between the various subsystems of the GSM-R system, including the transmission supporting units necessary for the GSM-R system to provide basic services, such as transmission light, cable and transmission Equipment, but does not include the connection channel between the remote unit and the near-end unit of the repeater, nor does it include the antenna feeder connection.
Specific practical applications
Xiamen-Shenzhen High-speed Railway, Guangzhou-Shenzhen-Hong Kong High-speed Railway, Qinghai-Tibet Line, Daqin Line, Jiaoji Line, Wuguang Line, Zhengxi Line, Xinfeng Town Marshalling Station , Shi-Tai Line, He-Ning Line, He-Wu Line, Beijing-Tianjin Intercity Line, Beijing-Shanghai High-speed Railway, etc.
Supplementary information
Dedicated radio communication for railway staff between a fixed point and a mobile point or between a mobile point and a mobile point, mainly including train radio communication, station radio communication, and radio alarm Devices, and other radio communications used by railway workers. Railway mobile communication is an indispensable means of communication to ensure traffic safety, prevent operation accidents, improve transportation efficiency, accelerate locomotive turnover, and improve service quality. It is an important part of railway communication.
A brief history of development
As early as the 1920s, railways in some countries began to experiment with wireless communication between locomotives and the ground. In the 1940s, many countries successively installed electronic tube radio telephones on trains, using medium and short wave bands. In the 1950s, short-wave band point-to-point wireless communication was generally used. In the 1960s, with the development and application of transistors and integrated circuits, railway mobile communications adopted a large number of very high frequency (VHF) and ultra-high frequency (UHF) frequency bands, and adopted site selection, duplex, and multi-user communication for networking. In terms of equipment, the volume is reduced, the weight is reduced, the power consumption is reduced, the reliability is increased, and it can adapt to various climatic conditions. After the 1970s, the combination of microprocessors and transceivers made the equipment signaling more complete and flexible, with functions such as automatic channel search, automatic user access, automatic power control, and automatic monitoring of equipment failures. Railways in some countries have begun to use wireless telephones for train passengers that can be connected to wired telephone networks. In the 1980s, apart from being used in railway train dispatching and commanding, railway mobile communications were also widely used in various railway business departments.
In the 1950s, Chinese railway station attendants and line attendants in marshalling yards began to use train wireless dispatch telephones and station wireless telephones, using electronic tube equipment with operating frequencies of 2MHz and 40MHz. In the early 1970s, all transistor devices were switched to 150MHz and 450MHz frequency bands. In the early 1980s, small-scale 150MHz and 450MHz intra-station wireless phones were promoted and applied in the marshalling yard. The use of wireless phones for maintenance workers along the railway has also been promoted one after another. The alarm wireless devices for road maintenance and construction have also been rapidly developed and applied, and the train wireless dispatch telephone test in the mountain tunnel section has been carried out.
Purpose
Train wireless communication
Communication between the personnel on the running train and the dispatcher or other personnel on the ground. It includes train wireless dispatch telephone and train passenger wireless telephone.
Train wireless dispatch telephone
The wireless telephone used by dispatchers to dispatch and command locomotives running along the line. The wireless train dispatching telephone of China Railway is used by dispatchers and station attendants to dispatch and command train drivers and train captains traveling along the line. Stations along the railway line are distributed across the country in strips. Each station is equipped with low-power radio stations and switching devices, and the locomotives are equipped with radio stations and control boxes. The dispatcher connects to the station radio (or fixed radio) through a wired or wireless circuit, and then the station radio (or fixed radio) connects with the locomotive station in the field strength coverage area through a wireless channel, thus forming a peace between the dispatcher and the driver. The station attendant and the driver talk to each other.
The train wireless dispatching phone uses the 150MHz and 400MHz frequency bands, the channel interval is 25kHz, and the simplex communication method is adopted in the section where the transportation business is not busy. The two parties use the same frequency to alternately send and receive calls. This system has the characteristics of flexible networking and simple equipment. In the increasingly busy section of railway transportation and the use of wireless phones is increasing, in order to quickly and reliably connect, countries in the world now successively use duplex or half-duplex communication methods for transmitting and receiving at different frequencies. It adopts audio combined type or digital coded selective call, and is accompanied by emergency call function and sending dispatching command and various instruction information functions. There are two ways to divide the coverage area of the train wireless dispatch telephone: one is for large areas with low traffic density and not busy traffic; the other is for small areas with high traffic density and busy traffic. In addition, because it is difficult for the radio waves in the ultra-high frequency band to propagate in the tunnel, the parallel waveguide line induction propagation method was used in the early stage, but the transmission field strength of this method is uneven, and the attenuation is often increased due to poor insulation. Especially in the electric traction section, a high interference voltage will be induced, which endangers the safety of maintenance personnel. Later, many countries used leaky coaxial cables. This type of cable opened a series of slots or slits on the outer conductor of the coaxial tube, so that part of the energy of the electromagnetic wave transmitted in the cable leaked from the slots to the space along the line. The attenuation is relatively uniform without fluctuations, and is easily received by the receiving device. This kind of leaky cable has a wide transmission frequency band, which can not only communicate but also transmit various data information. In the long tunnel area, due to the large attenuation of the leaky cable, it is necessary to install a repeater in the tunnel to compensate for the transmission loss, and the repeater needs to supply power from a long distance.
Train passenger wireless telephone
Passengers can use the radio public equipment on the train to connect to the local telephone network through the ground radio equipment and switching devices set along the line, and through the switching equipment. Relevant users, or communicate with long-distance users via long-distance line transmission.
Wireless communication within the station
A wireless communication used for operation command and business contact in the railway station yard. There are mainly passenger and freight station wireless phones and marshalling station wireless phones.
Passenger and freight station wireless telephones are mainly used for operational operations and loading and unloading operations between freight personnel, as well as communication between passenger transportation personnel.
Marshalling station wireless telephone
For various operators such as marshalling yard, train and vehicle maintenance personnel, iron shoe brakes, etc. Train number clerk, train attendant for receiving and dispatching trains, and mobile personnel performing shunting operations on dedicated lines communicate and communicate according to their own different systems. According to the nature of the operation and different needs, it is divided into a dozen independent wireless communication systems to form a small area communication network. For wireless phones used by people who work between vehicles, because the propagation of radio waves is affected by the antenna height and shielding effects of vehicles, human bodies, and portable radios, the best frequency band should be selected for communication. The portable telephone used by operators such as shunting and inspection has the characteristics of small size, low power consumption, light weight and high reliability, and can meet the requirements of rainproof, shockproof and all-weather.
Main performance
The main performance of the wireless communication equipment in the station is: the transmitter clutter suppression ratio is usually required to be above 60dB, the combined wave suppression ratio is required to be above 70dB, and the receiver is blocked. The attenuation should be above 80dB, and the intermodulation immunity should be above 60dB.
The radio alarm device is set up to prevent trains from entering the line maintenance and construction section, and to prevent accidents at crossings, bridges, and tunnels, and to warn the driver, between the driver and the construction section, between the driver and the crossing. Between the driver and the road worker. This device must be absolutely reliable and have a special use mark. Its operating distance is within a few kilometers, the alarm time is about 10 minutes, the use of a nationally unified dedicated frequency, and automatic detection as much as possible.
The wireless communication used by other railway staff mainly includes the wireless telephone used by the operation and maintenance personnel in the section, and the telephone widely used in other railway tasks, such as survey construction, maintenance operations, rescue trains, railway police Waiting for the wireless phone. These wireless phones use civilian frequency bands and do not occupy railway dedicated frequencies, so as not to interfere with transportation scheduling operations. Intercom wireless telephones generally use universal portable wireless telephones. In order to facilitate the work needs of railway public security personnel, wireless phones often communicate with wired phones, and various types of railway mobile communication networks with different functions are formed according to user needs.
Origin
GSM-R communication technology originated in Europe, and has now entered commercial use in most countries such as Germany, Switzerland, the Netherlands, Italy, and Sweden. Because GSM-R has functional advantages to adapt to the characteristics of railway transportation, and is more in line with the needs of the development of integrated communication and signal technology, the Ministry of Railways formally determined GSM-R as the development direction of my country's railway dedicated communications at the end of 2000.
GSM-R adds a special dispatching communication function for railway transportation to the GSM public mobile communication system platform. The GSM-R communication system includes: switches, base stations, locomotive integrated communication equipment, mobile phones and other equipment. Take the Qinghai-Tibet Railway as an example: The Qinghai-Tibet Railway is the highest railway line in the world. The Qinghai-Tibet Railway starts in Golmud City, Qinghai Province in the north, passes through Nachitai, Wudaoliang, Tuotuo River, Yanshiping, and crosses Tanggula Mountain and enters the Tibet Autonomous Region. It passes through Amdo, Nagqu, and Damxung to Lhasa, the capital of the Tibet Autonomous Region, with a total length of about 1142km. Most of the lines are in no-man's land where there is no oxygen on the plateau. In order to meet the needs of railway transportation communication, signal and dispatch command, the GSM-R mobile communication system is adopted.
GSM-R is based on the GSM technical standard. Because GSM-R focuses on railway applications, in the current network, GSM-R has three more main functions than the public network, namely the voice group call service VGCS , Voice broadcast service VBS and enhanced multi-priority and forced demolition eMLPP are also collectively referred to as advanced voice call project ASCI service. It is precisely because of this difference that the products of manufacturers supporting public network GSM cannot be directly used in the GSM-R network, unless the ASCI service is specifically developed. Currently, manufacturers supporting GSM-R include ZTE, Nokia Siemens Networks (Nosi), Huawei, and COMLAB. , Kapch (formerly Nortel, acquired by Kapch), etc.
The business of dispatching communication system includes train dispatching communication, freight dispatching communication, traction substation dispatching communication, other dispatching and dedicated communication, station communication, emergency communication, construction maintenance communication and crossing communication.
2. Train number transmission and train stop information transmission function
The train number transmission and train stop information are of great significance to railway transportation management and train safety. It can pass The data acquisition and transmission application system based on GSM-R circuit switching technology can realize data transmission, and it can also be realized by GPRS.
3. Dispatching command transmission function
The railway dispatching command is a written order issued by the dispatcher in the dispatching station to the driver. It is an important guarantee for the safety of train operation. Using the GSM-R system transmission channel to transmit scheduling commands will undoubtedly speed up the transmission process of scheduling commands and improve work efficiency.
4. The information transmission function of the tail device of the train
Incorporating the tail wind pressure data feedback transmission channel into the GSM-R communication system can easily solve the problem of tail wind pressure data transmission.
5. Shunting locomotive signal and monitoring information system transmission function
Provide shunting locomotive signal and monitoring information transmission channel to realize data transmission between ground equipment and multiple on-board equipment, And can store the relevant information of entering and exiting the shunting mode.
6. Train control data transmission function
Using GSM-R communication system to realize two-way wireless data transmission between train and ground, and provide two-way safe data transmission channel between train and ground.
7. Inter-area mobile official communications
The internal communications of hydropower, engineering, signal, communications, power supply, bridge guarding and other departments operating in the inter-area can all use GSM-R operation handheld If necessary, operators can contact station attendants, dispatchers of various departments or automatic telephone users when needed. In an emergency, the operator can also call the driver and establish a call with the driver.
8. Emergency command and communication voice and data services
The emergency communication system is used to communicate with the emergency site in the event of natural disasters or emergencies that affect railway transportation. The GSM-R communication system is used between rescue centers and inside the scene to establish voice, image, and data communication systems.