System and Apparatus For Determining the Position of Railbound Vehicles on a Railway System

Abstract

A method and system for determining a position of a rail-bound vehicle on a railway is disclosed. The apparatus comprises: a transmitter and receiver for wireless communication with at least one base station arranged at a predetermined position in the vicinity of the railway; a measurement device to determine a distance to said at least one base station based on measurements of the radio signals of said wireless communication in the time domain and/or phase domain; and a controller arranged to determine a present position of said vehicle on said railway based on said distance. A control system/method for controlling rail-bound vehicles in a railway system, and/or an internal or external system related to such rail-bound vehicles, using such position determination is also disclosed.

Claims

1. A control system for controlling rail-bound vehicles in a railway system, the control system comprising a controller arranged to determine present positions of rail-bound vehicles on at least one railway of the railway system, and to issue control signals to control the operation of said vehicles, wherein the present positions of said vehicles are determined based on radio signal measurements in at least one of the time domain and/or phase domain of wireless communication occurring between each vehicle and base stations arranged at predetermined positions in the vicinity of said railways.

2. The control system of claim 1, wherein the radio signal measurements comprises measuring of a propagation time for radio signals transferred between the vehicles and the base stations.

3. The control system of claim 2, wherein the propagation time is measured by measuring a round-trip time for a data packet to be sent from a first party to a second party, and a response to be sent back from the second party to the first party, and subtracting the round-trip time with a processing time of the second party before sending the response.

4. The control system of claim 1, wherein the radio signal measurements comprises measuring of a phase difference of radio signals of different frequencies transferred between the vehicles and the base stations.

5. The control system of claim 1, wherein the control system is a CBTC (Communication Based Train Control) system.

6. The control system of claim 1, wherein the wireless communication is at least one of made by over a Wireless Local Area Network (WLAN) and made via a cellular network standard.

7. The control system of claim 6, wherein the wireless communication is made by at least one of: WLAN and GSM-R.

8. The control system of claim 1, wherein the base stations are trackside base stations distributed along the extension of the railway(s).

9. The control system of claim 8, wherein the trackside base stations are access points for communication in compliance with a WLAN standard.

10. The control system of claim 1, wherein the controller is further arranged to determine at least one of travelling speed and travelling direction for said rail-bound vehicles based on said radio signal measurements.

11. The control system of claim 1, said system being adapted to control at least one of start, speed and stop of the rail-guided vehicles on said railway(s) based on said issued control signals.

12. The control system of claim 1, further comprising a sensor arranged to determine which track that is selected when the vehicle passes through a junction.

13. A method for controlling rail-bound vehicles in a railway system, the method comprising: measuring a radio signal in at least one of the time domain and/or the phase domain of wireless communication occurring between each vehicle and base stations arranged at predetermined positions in the vicinity of said railways; determining present positions of the rail-bound vehicles on at least one railway of the railway system based on said measurements; and issuing control signals to control the operation of said vehicles based on said determined present positions.

14. An apparatus for determining a position of a rail-bound vehicle on a railway, the apparatus comprising: a transmitter and receiver for wireless communication with at least one base station arranged at a predetermined position in the vicinity of the railway; a measurement device to determine a distance to said at least one base station based on measurements of the radio signals of said wireless communication in at least one of the time domain and the phase domain; and a controller arranged to determine a present position of said vehicle on said railway based on said distance.

15. The apparatus of claim 14, wherein the apparatus is comprised within a mobile router arranged within the rail-bound vehicle.

16. A method for determining a position of a rail-bound vehicle on a railway, the method comprising: providing wireless communication with at least one base station arranged at a predetermined position in the vicinity of the railway; measuring a distance to said at least one base station based on measurements of the radio signals of said wireless communication in at least one of the time domain and the phase domain; and determining a present position of said vehicle on said railway based on said distance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] For exemplifying purposes, the invention will be described in closer detail in the following with reference to embodiments thereof illustrated in the attached drawings, wherein:

[0048] FIG. 1 is a schematic illustration of a train having a wireless communication system in accordance with an embodiment of the present invention;

[0049] FIG. 2 is a schematic illustration of a train being associated with two trackside base stations of an external mobile network;

[0050] FIG. 3 is a schematic illustration of an antenna configuration to be used on trains in the systems of FIGS. 1 and 2;

[0051] FIG. 4 is a schematic illustration of a control system/apparatus in accordance with an embodiment of the present invention;

[0052] FIG. 5 is a schematic illustration of determination of a distance based on propagation time measurement;

[0053] FIG. 6 is a schematic illustration of determination of a distance based on phase differences; and

[0054] FIG. 7 is a schematic illustration of determination of track selection at branches.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0055] In the following detailed description, preferred embodiments of the invention will be described. However, it is to be understood that features of the different embodiments are exchangeable between the embodiments and may be combined in different ways, unless anything else is specifically indicated. Even though in the following description, numerous specific details are set forth to provide a more thorough understanding of the invention, it will be apparent to one skilled in the art that the invention may be practiced without these specific details. In other instances, well known constructions or functions are not described in detail, so as not to obscure the invention. In the detailed embodiments described in the following are related to trains. However, it is to be acknowledged by the skilled reader that the method and system are correspondingly useable on other rail-bound vehicles. In particular, the invention is very well suited for use in underground railway systems.

[0056] In FIG. 1 a schematic illustration of a rail-bound vehicle 1, such as a train, having a communication system. In this embodiment, the communication system comprises a data communication router 2 for receiving and transmitting data between an internal local area network (LAN) 3, and one or several external wide area networks (WANs) 4a, 4b, 4c, and preferably including at least one external network having a plurality of trackside base stations/access points distributed along a vehicle path of travel, preferably for communication in compliance with a Wireless Local Area Network (WLAN) standard, such as an 802.11 standard.

[0057] Communication to and from the WANs is provided through one or several antennas 5 a-n arranged on the train, the antennas may be arranged on the roof of the train, on window panes of the train, etc. Two or more data links are preferably available, either between the train and one of the WANs, and/or by using several WANs simultaneously.

[0058] The LAN is preferably a wireless network, using one or several internal antennas to communicate with terminal units 6 within the vehicle. It is also possible to use a wired network within the vehicle. The LAN may be set-up as wireless access point(s). The client(s) 6 may be computing devices such as laptops, mobiles telephones, PDAs, tablets and so on.

[0059] The data communication router further preferably comprises a plurality of modems 21 a-n. Assignment of data streams to different WANs and/or to different data links on one WAN is controlled by a router controller 23. The router controller 23 is preferably realized as a software controlled processor. However, the router controller may alternatively be realized wholly or partly in hardware.

[0060] The system may also comprise a receiver for receiving GNSS (Global Navigation Satellite System) signals, such as a global positioning system (GPS) receiver 7 for receiving GPS signals, indicative of the current position of the vehicle. The GNSS/GPS signals may be used for providing positioning data for applications which are less critical, and where the requirements for exactness and security are low. It may also be used as a complement to the position determination based on radio signal measurement, discussed in more detail below, to improve the accuracy and robustness of this even further.

[0061] The data communication router may also be denominated MAR (Mobile Access Router) or MAAR (Mobile Access and Applications Router).

[0062] In FIG. 2, the external wide area network (WAN) including a plurality of trackside base stations, such as trackside access points, distributed along a vehicle path of travel, i.e. the rail, for communication in compliance with a Wireless Local Area Network (WLAN) standard, such as an 802.11 standard, is illustrated in more detail. The external mobile network comprises a plurality of trackside base stations 11, 12, arranged along the vehicle path. The antenna devices have coverage areas 11a, 11b, 12a, 12b extending in both directions along the vehicle path. The coverage areas on the two sides of the antenna devices may be related to the same base station/access point, or to different base stations/access points. Thus, coverage area 11a and 11b may be related to the same base station/access point, or be operated independently, as different base stations/access points, and the same applies to coverage areas 12a and 12b, etc.

[0063] The base stations/access points are connected to a controller 9, via a wired or wireless connection, such as via a fiber connection. The controller is preferably realized on a processor, and at least partly in software. However, the controller may also be realized on several processors, in a distributed fashion. The coverage areas may be overlapping, allowing the mobile router of the vehicle to access several access points simultaneously, and thereby distribute the communication between several data links.

[0064] The mobile router may also be connected to other external networks, and may consequently simultaneously distribute the communication also over these networks.

[0065] Thus, the vehicle preferably comprises a plurality of antennas, for communicating with different links and different external networks. A schematic illustration of this is provided in FIG. 3. This antenna arrangement, for example arranged on the roof of the train, may comprise directional antennas 51a and 51b directed to access points in the backward direction of the train, directional antennas 52a and 52b directed to access points in the forward direction of the train, and additional antennas 53-56 arranged to communicate with base stations of other external networks, e.g. via GSM, Satellite, DVB-T, HSPA, EDGE, 1RTT, EVDO, LTE, Wi-Fi (apart from the trackside WLAN) and WiMAX. However, antennas may also be arranged at the front and aft side of the train. Such positioning of the antennas is particularly useful for trains travelling in tunnels, since a more central placement of the antennas increases the line of sight.

[0066] In the above-discussed exemplary embodiment, the control system for controlling rail-bound vehicles in a railway system, and/or for controlling internal or external systems related to such vehicles, and in particular for determining position of the vehicle, to be discussed in more detail in the following, may be realized in a communication system as discussed above, which also enables communication for client devices in the vehicle with one or several external network(s). However, the control system may also be realized in a train communication system only enabling communication with the external network(s) for an operation system of the vehicle, for the driver of the vehicle, or the like. The control system may also be realized as a dedicated system, only for use in determining a position of the vehicle. Further, additionally or alternatively, the control system may be arranged externally from the vehicle, and may e.g. be connected to or arranged in one or several of the trackside base stations, or be arranged in or connected to the controller 9.

[0067] The control system or apparatus 100, as schematically shown in FIG. 4, comprises a controller 101 arranged to determine present positions of rail-bound vehicles on at least one railway of the railway system, and to issue control signals to control the operation of said vehicles, and/or said internal or external system, based on said determined present positions.

[0068] The control system further comprises, or is connected to, a transmitter and receiver 102 for wireless communication with at least one base station arranged at a predetermined position in the vicinity of the railway, and a measurement device 103 to determine a distance to the at least one base station based on measurements of the radio signals of the wireless communication in the time domain and/or phase domain. The controller 101 is arranged to determine a present position of the vehicle on said railway based on said distance.

[0069] The fixed positions of the base stations may be stored in a database 104, which may be included in the control system, or be connected to the control system. The exact location of the base stations can be received from the operators, or could be identified by initialization measurements. The database may also comprise data at least about the identity of the base stations and the position of the base stations, and optionally also about the coverage area of the trackside base stations in relation to the vehicle path.

[0070] The transmitter and receiver 102 used for the wireless communication for determining the distance to the base stations may occur over a dedicated wireless communication system, e.g. a communication system provided for safe and reliable communication between the train and an external control center, such as the dedicated wireless communication system GSM-R. However, the wireless communication may additionally or alternatively occur over other types of wireless communication, such as by WLAN communication, such as in accordance with the IEEE 802.11 standard, or communication via one or several of presently available 3G, 4G and 5G standards may also be used with the same safety and reliability. The data packets used for determination of the distance may be transmitted for the sole purpose of positioning, or may be normal payload-carrying data packets within the communications link, upon which the aforementioned measurements are performed.

[0071] In accordance with one embodiment of the invention, as illustrated in FIG. 5, the radio signal measurements comprise measuring of a propagation time for radio signals transferred between the vehicles and the base stations. In particular, the propagation time may be measured by measuring the round-trip time for a data packet to be sent from a first party to the other party, and a response to be sent back from the second party to the first party, and subtracting the round-trip time with a processing time of the second party before sending the response.

[0072] Having determined the propagation time for signals travelling from the vehicle to the base station or from the base station to the vehicle, it is simple to determine the exact distance, since the radio signals travels with the speed of light. Thus, the distance may be calculated as the propagation time multiplied with the speed of light. By knowing the distance to the base station, and by knowing the fixed position of the base station, as well as the fixed path of the railway track, it is possible to determine with great exactness the position of the vehicle travelling on the railway track.

[0073] An example of such a measurement is schematically illustrated in FIG. 5. An initiating party, which is here the vehicle-based equipment, but may also be a wayside base station, records the time-of-departure t.sub.1 of a data packet sent over the air. A responding party, here the base station, receives the data packet, recording the time-of-reception, t.sub.2. The responding party, i.e. here the base station, then transmits a response data packet and records the time-of-departure, t.sub.3. The initiating party, i.e. here the onboard equipment, notes the time-of-reception, t.sub.4.

[0074] The control system, being the initiating party, then calculate the round-trip propagation time t.sub.p as follows:

t.sub.p=(t.sub.4t.sub.1)(t.sub.3t.sub.2)

[0075] i.e. by subtracting the responding party's processing time from the total round-trip time.

[0076] The distance d between the train and the base station is then calculated by multiplying the one-way propagation time, corresponding to the round-trip propagation time divided by two, with the speed of light c:

d=t.sub.p/2*c

[0077] In accordance with another embodiment of the invention, the radio signal measurements comprise measuring of a phase difference of radio signals of different frequencies transferred between the vehicles and the base stations. This is schematically illustrated in FIG. 6. Here, the control system is arranged in the vehicle, but as already discussed, the control system may additionally or alternatively be arranged at the base station. The base station transmits signals to the train over a plurality of different frequencies, and consequently, the signals will be received at the vehicle at different phases .sub.1, .sub.2, .sub.3, . . . .

[0078] The distance is then determined based on the difference in phase between signals received at the various possible frequencies of operation, utilizing the fact that the signal phase at the receiving station with respect to the phase at the transmitting station is dependent on: a) the carrier frequency, and b) the distance between the transmitting and the receiving station. Thus, the phase set for each position is unique within a range of plausible distances from the base stations, and by determining the phase of the received signal with respect to the transmitted signal at a plurality of carrier frequencies, the distance between the transmitting and receiving stations can be determined as it will represent the only mathematically possible solution to a system of equations describing the phases of signal received with respect to signals transmitted of each carrier frequency as functions of the distance between the transmitting and receiving stations.

[0079] In yet another embodiment, the distance between the vehicle and the base station is determined based on signal strength/power, since the signal strength/power will diminish as a function of the distance.

[0080] It is also possible to determine the distance based on any combination of two or more of the above-discussed methodologies.

[0081] In addition to determining the distance between the vehicle and base stations, and to determine the position of the vehicle based on the determined distances, the control system/apparatus may also be arranged to determine at least one of travelling speed and travelling direction for the rail-bound vehicles based on the radio signal measurements. This can e.g. be done by storing position data for the vehicle for one or several previously made determinations in a database 105, and to make calculations based on the differences. Similarly, the controller can hereby also determine acceleration and deceleration for the vehicles.

[0082] In order to be able to determine which of the two or more tracks that has been chosen when passing through a junction with greater precision, the control system may further include a sensor 106 arranged to determine which track that is selected. The sensor 106 may e.g. be a signal sensor/receiver, receiving signals from transponders 200, balises or the like, arranged on one or both/several of the tracks branching out at the junction, as shown schematically in FIG. 7. However, other types of sensors may also be used. For example, the sensor may be a GNSS sensor, receiving GNSS signals, such as GPS signals, and thereby enabling determination of which track that has been selected. The sensor may also be an acceleration sensor, a gyro sensor or the like, being capable of determining in which direction and how fast the vehicle turns, a camera being able to determine the track based on image analysis, etc.

[0083] The control system may be integrated with, or be connected to, a control system automatically or semi-automatically controlling e.g. start, stop and speed of rail-bound vehicles travelling on a railway network, based on the issued control signals. For example, the control system of the present invention may be, or form a part of, a CBTC (Communication Based Train Control) system. Additionally or alternatively, the issued control signals related to the position of the vehicle may be used in internal or external systems related to such vehicles, e.g. for value-adding automated processing, such as to allow a technological system, either onboard the train, or remote, to automatically generate more complex information based on the position information, for the purpose of relieving persons of strenuous manual and mental processing.

[0084] The above-described embodiments of the invention can be implemented in any of numerous ways. For example, the embodiments may be implemented using hardware, software or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computer or distributed among multiple computers.

[0085] Also, the various methods or processes outlined herein may be coded as software that is executable on one or more processors that employ any one of a variety of operating systems or platforms. Additionally, such software may be written using any of a number of suitable programming languages and/or conventional programming or scripting tools, and also may be compiled as executable machine language code.

[0086] Such and other obvious modifications must be considered to be within the scope of the invention, as it is defined by the appended claims. It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting to the claim. The word comprising does not exclude the presence of other elements or steps than those listed in the claim. The word a or an preceding an element does not exclude the presence of a plurality of such elements.