Communication System

Abstract

The present invention relates to a communication system for communicating between at least one vehicle (4; 5) and a fixed-position base station (6), wherein the at least one vehicle travels along a predetermined motion trajectory, wherein the communication is performed using a slot waveguide (1) extending parallel to the motion trajectory of the vehicle (4; 5), wherein at least one antenna (16A, 16B; 17A, 17B; 18A, 18B) connected to a transmitting and receiving device (10; 11; 12) of the fixed-position base station (6) and at least one antenna (21A, 21B; 22A, 22B) of the vehicle (4; 5) extend into the slot waveguide, wherein when the vehicle (4; 5) moves, the antenna (21A, 21B; 22A, 22B) of the vehicle (4; 5) extends along the slot waveguide (1). The slot waveguide (1) moves in the longitudinal direction, the slot waveguide (1) comprises at least two sections (1A; 1B; 1C; 1D) separated from each other by gaps (7; 8; 9), each section (1A; 1B; 1C; 1D) of the slot waveguide (1) is provided with at least one antenna (16A, 16B; 17A, 17B; 18A, 18B) extending into the corresponding section (1A; 1B; 1C; 1D), and two mutually adjacent antennas (16A, 16B; 17A, 17B; 18A, 18B) extending into different sections (1A; 1B; 1C; 1D) of the slot waveguide (1) are respectively coupled via coupling devices (13; 14; 15) not only to the common transmitting and receiving device (10; 11; 12) of the fixed base station (6), but also to each other.

Description

Technical Field

[0001] The invention relates to a communication system according to the preamble of claim 1. Background Art

[0002] Such a communication system is known, for example, from DE 10 2013 002 227 B4. It enables high-bandwidth and interference-resistant communication between a vehicle traveling along a predetermined trajectory and a stationary base station. An antenna is accordingly positioned on the vehicle, extending through a slot into the cavity of a slot waveguide and capable of receiving and / or transmitting electromagnetic waves propagating along the waveguide while the vehicle is traveling. The corresponding antenna of the stationary base station is positioned at one end of the slot waveguide.

[0003] In such systems, the effective range of communication is limited by the attenuation of electromagnetic waves propagating along the slot waveguide. In addition, longer slot waveguides must be assembled from multiple sections, which causes deformation problems due to thermodynamic length changes when the temperature changes. Summary of the Invention

[0004] The object of the present invention is therefore to provide an advantageous solution for long-distance communication for a communication system of the aforementioned type, which solution enables reliable communication even for longer vehicle movement trajectories.

[0005] This object is achieved according to the invention by a communication system having the features of claim 1. Advantageous embodiments are specified in the dependent claims.

[0006] According to the present invention, in a communication system in which a vehicle traveling along a predetermined motion trajectory communicates with a fixed base station using a slot waveguide extending parallel to the vehicle's motion trajectory, at least one antenna connected to the vehicle's transmitting and receiving device and at least one antenna connected to the transmitting and receiving device of the fixed base station extend into the slot waveguide, wherein when the vehicle moves, the vehicle's antenna moves along the longitudinal direction of the slot waveguide, and the slot waveguide includes at least two sections separated from each other by gaps, and each section of the slot waveguide is provided with at least one antenna extending into the corresponding section, and two adjacent antennas extending into different sections of the slot waveguide are respectively coupled via coupling devices not only to the common transmitting and receiving device of the fixed base station, but also to each other.

[0007] The gaps between the slot waveguide segments allow the thermodynamic lengths of each segment to vary. By placing a corresponding antenna in each segment, a transceiver can communicate with the vehicle in the area of both segments. Furthermore, coupling the two segments via a coupling device bridges the gap between them, enabling communication from one segment to the other across the gap. This is particularly important for interference-free communication, as a vehicle's transceiver must be able to receive transmitted signals from other vehicles in order to detect conflicts with its own transmitted signals or to prevent them from occurring in the first place.

[0008] In a first advantageous embodiment, the coupling device comprises a reciprocal reactive / reactive two-way power splitter having an input connection connected to the transceiver device and two output connections connected to one of the antennas. The input and output connections indicate the transfer direction in which the fed-in power is split into two lower power components, but the transfer behavior is reciprocal.

[0009] Alternatively, in a second advantageous embodiment, the coupling device comprises a reciprocal two-way power splitter and two reciprocal two-way directional couplers, wherein the input connections of the directional couplers are each connected to one of the antennas, the output connections of each directional coupler are each connected to a corresponding output connection of the other directional coupler, and the other output connection of each directional coupler is each connected to one of the output connections of the power splitter, whose input connections are connected to the transceiver. Here, the input and output connections of the power splitter and directional coupler also indicate the transfer direction for splitting the fed-in power into two lower power components, but the transfer behavior is also reciprocal.

[0010] Particularly advantageously, a form of power splitter used in the second embodiment is a Wilkinson power splitter. A structural unit with four external connections can also advantageously be formed from two two-way directional couplers, each connected to one another at an output connection.

[0011] The power splitter used in both embodiments of the coupling device is preferably symmetrical, i.e., the power fed in at the input is divided into two equal partial powers at the two outputs, but due to unavoidable losses, each partial power is less than half the fed power. Using a symmetrical power splitter is particularly advantageous when the slot waveguide sections to which the power output by the transceiver is to be distributed are of equal length. In opposite transmission directions, when a signal is fed into one of the output connections, the proportion of the fed power available at the input connection remains the same, regardless of which input connection the signal is fed into.

[0012] In a third advantageous embodiment of the coupling device, the coupling device comprises a reciprocal two-way tap having a branch connection and two through connections, wherein the branch connection is connected to the transceiver device and the through connections are each connected to one of the antennas. A particular advantage of the tap is the low insertion loss between the two through connections, which is particularly advantageous for low-loss coupling of two antennas in different sections of the slot waveguide and, therefore, for direct signal transfer from one section to the other.

[0013] In a third embodiment of the coupling device, the tap is preferably symmetrical, i.e., when a signal is fed into the branch connection, the fed power is coupled to each of the two through-connections in equal proportions, with losses occurring therein so that the power available at both through-connections is essentially less than half the fed power. Using a symmetrical tap is particularly advantageous when the slot waveguide sections to which the power output of the transceiver is to be distributed are of equal length. In the opposite transmission direction, when a signal is fed into one of the through-connections, the proportion of the fed power available at the branch connection is the same, regardless of which through-connection the signal is fed into.

[0014] The present invention is not limited to slot waveguides consisting of two sections. Instead, it is particularly useful when the slot waveguide has multiple sections, each separated by gaps, and multiple transceiver devices are provided, each of which is connected via an assigned coupling device to two antennas extending into different sections of the slot waveguide. This means that the present invention can also realize very long transmission paths for transportation systems with very long vehicle movement paths.

[0015] If the slot waveguide consists of multiple sections and multiple different transceiver devices of a stationary base station are provided accordingly, these can also communicate with the transceiver device of the vehicle at least partially via different channels. Because the individual sections are directly connected via coupling devices, signals can also be transmitted between the stationary transceiver device and the vehicle's transceiver device via the gaps between different slot waveguide sections. The vehicle is located in the area of another slot waveguide section, and the antenna of the stationary transceiver device does not extend into this other slot waveguide section. This enables simultaneous communication in different channels across the boundaries of the slot waveguide sections. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The embodiments of the present invention are described below with reference to the accompanying drawings.

[0017] Figure 1 shows a schematic cross-sectional view of a slot waveguide together with an antenna extending into the slot waveguide,

[0018] Figure 2 Show the basis Figure 1A schematic longitudinal sectional view of a slot waveguide together with a block diagram of other components of a communication system according to the present invention,

[0019] Figure 3 The circuit symbol showing a reactive two-way power splitter suitable as a coupling device,

[0020] Figure 4 A block diagram showing a combination of two directional couplers and a two-way power splitter suitable as a coupling device,

[0021] Figure 5 A circuit symbol showing a two-way tap suitable as a coupling device. DETAILED DESCRIPTION

[0022] Figure 1 A schematic cross-sectional view of a slot waveguide 1 is shown, which illustrates how the slot waveguide is used in a communication system in the prior art for communicating between vehicles 4 and 5 traveling along a predetermined motion trajectory. Figure 2 ) and a fixed base station 6 and / or between multiple such vehicles 4 and 5. The vehicle's antenna 3 extends through the slot 2 into the slot waveguide 1 to transmit and receive electromagnetic waves propagating along the slot waveguide 1. As the vehicle 4 or 5 moves along its predetermined trajectory, the antenna 3 moves along with the vehicle in the longitudinal direction of the slot waveguide 1. In particular, a track can be used to guide the vehicle 4 or 5 along a predetermined route.

[0023] like Figure 2 As shown, the slot waveguide 1 is composed of a plurality of independent segments 1A, 1B, 1C, and 1D, each separated from another by gaps 7, 8, or 9. Gaps 7 to 9 are necessary because the length of the slot waveguide 1 precludes its realization as a single piece, and it is necessary to allow the segments 1A to 1D to change length when the temperature changes. Due to the large total length of the slot waveguide 1, a stationary base station 6 is connected to a plurality of transceiver devices 10, 11, and 12, hereinafter referred to as transceivers, which are distributed along the slot waveguide 1. Each transceiver 10 to 12 is connected via a coupling device 13, 14, or 15 to two antennas 16A and 16B, 17A and 17B, or 18A and 18B, which extend into one of two adjacent segments 1A and 1B, 1B and 1C, or 1C and 1D of the slot waveguide 1, respectively. Thus, signals can be input from the transceiver 10 to the sections 1A and 1B via the coupling device 13, or signals from these sections 1A and 1B can be output to the transceiver 10 via the coupling device 13. The same is true for the sections 1B and 1C, the transceiver 11 and the coupling device 14, and for the sections 1C and 1D, the transceiver 12 and the coupling device 15.

[0024] Vehicles 4 and 5 are also each equipped with a transceiver device 19 or 20, referred to below as a transceiver, each having two antenna connections and connected via these connections to two antennas 21A and 21B or 22A and 22B. Antennas 21A and 21B, as well as antennas 22A and 22B, are each spaced apart in the longitudinal direction of the slot waveguide 1 by a distance that is greater than the width of the gaps 7 to 9, so that in any possible position of the vehicle 4 or 5, one of the two vehicle antennas 21A or 21B or 22A or 22B always projects into one of the sections 1A to 1D of the slot waveguide 1 and is thus ready for transmission and reception.

[0025] With the above-described configuration, regardless of the current position of vehicles 4 and 5, bidirectional communication between the stationary base station 6 and vehicle 4 can be achieved at any time via at least one of the three transceivers 10 to 12, one of the coupling devices 13 to 15, one of the six fixed antennas 16A to 18B, and one of the vehicle-side antennas 21A or 21B and transceiver 19. This also applies to bidirectional communication between the stationary base station 6 and vehicle 5, where one of the vehicle-side antennas 22A or 22B and transceiver 20 participate in the communication.

[0026] According to the present invention, the fixed coupling device 13 not only connects the transceiver 10 to its assigned antennas 16A and 16B, but also connects the antennas 16A and 16B, respectively, protruding into one of the adjacent segments 1A and 1B of the slot waveguide 1. This also applies meaningfully to the coupling device 14 and segments 1B and 1C, as well as the coupling device 15 and segments 1C and 1D. That is, the coupling devices 13 to 15 also bridge the gaps 7 to 9, enabling signals to be transmitted through the gaps 7 to 9 along the slot waveguide 1 between its segments 1A to 1D. It will be appreciated that the coupling devices 13 to 15 cause a certain insertion loss between the antennas 16A and 16B, 17A and 17B, or 18A and 18B, respectively, connected thereto. However, this loss is significantly lower than the loss that would result from the gaps 7 to 9 without the coupling devices 7 to 9.

[0027] One possible implementation of any coupling device 13 to 15 is a reactive two-way power splitter 23, also called a distributor, which itself belongs to the prior art. Figure 3 The circuit symbol for this type of reactive two-way power splitter 23 is shown in FIG. It distributes the signal power fed into its input connection A1 to its output connections A2 and A3 according to a predetermined splitting ratio, but absorbs a portion of the fed power. In the case of a symmetrical power splitter, this splitting ratio is 1:1. In the reverse direction of operation, it acts as a combiner, combining the signal powers fed into connections A2 and A3 at connection A1.

[0028] A possible second embodiment of any coupling device 13 to 15 is Figure 4 The combination of two directional couplers 24 and 25 shown in FIG. , also known from the prior art, includes a two-way power splitter 26. Directional coupler 24 connects one input connection B1 directly to one output connection B2 and couples this input connection B1 to a second output connection B3 with low attenuation, but output connections B2 and B3 are not coupled to each other. The same applies to the second directional coupler 25, with input connection C1 and output connections C2 and C3. To implement one of the coupling devices 13 to 15 according to the present invention, the output connections B2 and C2 of the two directional couplers are connected to each other, while the other output connections B3 and C3 are connected to the output connections D2 and D3, respectively, of a two-way power splitter 26. According to the present invention, the input connection D1 of power splitter 26 is connected to one of the transceivers 13 to 15, while the input connections B1 and C1 of directional couplers 24 and 25 are connected to one of antennas 16A and 16B, 17A and 17B, or 18A and 18B, respectively.

[0029] Due to the reciprocity of directional couplers 24 and 25 and power divider 26, Figure 4 The interconnection of in principle functions equally well in both transmission directions, i.e., serves as both a power divider and a combiner. Instead of interconnecting two separate directional couplers 24 and 25, a directional coupler 27 with four connections B1, B3, C1 and C3 can also be used, which provides the same functionality and is already implemented in the form of a structural unit. This is in Figure 4 . In this variant, the two output connections D2 and D3 of the power splitter 26 should not be coupled to each other because the coupling between the input connections B1 and C1 of the directional couplers 24 and 25 is already established via their directly connected output connections B2 and C2. Therefore, in this variant, instead of the reactive power splitter 23, a more suitable power splitter 26 is a power splitter whose two output connections are not coupled to each other, in particular, a Wilkinson power splitter.

[0030] A third possible embodiment of any coupling device 13 to 15 is a two-way tap 28 , which likewise belongs to the prior art. Figure 5 The circuit symbol for a two-way tap 28 is shown. It couples a portion of the signal power fed into its branch connection E1 to through-connections E2 and E3 at a predetermined ratio. When using a symmetrical tap, this ratio is 1:1. In the opposite operating direction, it couples a portion of the signal power input to through-connections E2 and E3, respectively, to connection E1. While the coupling of branch connection E1 to each of through-connections E2 and E3 is accompanied by considerable attenuation, through-connections E2 and E3 couple to each other with relatively low attenuation.

[0031] The three variants of coupling devices 13 to 15 differ significantly in the insertion loss between the transceiver connections and the antenna connections, and between the antenna connections. Generally, the insertion loss is lowest in the two-way splitter 28 between antenna connections E2 and E3, while the insertion loss is lowest in the reactive two-way splitter 23 between transceiver connection A1 and antenna connections A2 and A3. In the case of the two directional couplers 24 and 25 combined with the two-way splitter 26, the insertion loss between antenna connections B1 and C1 is generally lower than in the case of the reactive two-way splitter 23 alone, but higher than in the case of the two-way splitter 28. Furthermore, the insertion loss between transceiver connection D1 and antenna connections B1 and C1 is higher than in the other two variants.

[0032] The choice of variant should be made taking into account the trade-offs between the different requirements. If the lowest possible insertion loss between adjacent segments of the slot waveguide 1 is crucial, a two-way tap is the optimal solution, while a combination of two directional couplers and a power splitter is a suboptimal solution. While an asymmetric power distribution ratio of the coupling devices 13 to 15 may be advantageous when the segments 1A to 1D of the slot waveguide 1 have different lengths, it is generally advantageous to select the lengths of all segments 1A to 1D to be equal and to accordingly configure the coupling devices 13 to 15 to have a symmetrical power distribution.

[0033] Low insertion loss between the antenna connections of the coupling devices 13 to 15 is particularly important if communication is desired between different fixed transceivers and different vehicle-mounted transceivers via different channels, wherein the channels represent frequency bands of a certain width. Figure 2 In the configuration, it is desirable that transceiver 11 communicate with transceiver 20 via a first channel X, and that transceiver 12 communicate with transceiver 19 via a second channel Y. To this end, the signal on channel X must be passed via gap 9, and the signal on channel Y must be passed via gap 8. To this end, it is desirable that the insertion attenuation of coupling devices 14 and 15 between antennas 17A and 17B or between antennas 18A and 18B is very low.

Claims

1. A communication system for communicating between at least one vehicle (4; 5) and a fixed-position base station (6), wherein the at least one vehicle travels along a predetermined motion trajectory, wherein the communication is performed using a slot waveguide (1) extending parallel to the motion trajectory of the vehicle (4; 5), wherein at least one first antenna (16A, 16B; 17A, 17B; 18A, 18B) connected to a transmitting and receiving device (10; 11; 12) of the fixed-position base station (6) and at least one second antenna (21A, 21B; 22A, 22B) of the vehicle (4; 5) extend into the slot waveguide, wherein when the vehicle (4; 5) moves, the second antenna (21A, 21B; 22A, 22B) of the vehicle (4; 5) moves in the longitudinal direction of the slot waveguide (1), It is characterized in that The slot waveguide (1) comprises at least two sections (1A; 1B; 1C; 1D) separated from each other by gaps (7; 8; 9), each section (1A; 1B; 1C; 1D) of the slot waveguide (1) is provided with at least one first antenna (16A, 16B; 17A, 17B; 18A, 18B) extending into the corresponding section (1A; 1B; 1C; 1D), two mutually adjacent first antennas (16A, 16B; 17A, 17B; 18A, 18B) extending into different sections (1A; 1B; 1C; 1D) of the slot waveguide (1) are respectively coupled via coupling devices (13; 14; 15) not only to a common transmitting and receiving device (10; 11; 12) of the stationary base station (6), but also to each other, It enables signals to be transmitted along the slot waveguide (1) via the gaps (7; 8; 9) between its sections (1A; 1B; 1C; 1D).

2. The communication system according to claim 1, wherein: The coupling device (13; 14; 15) comprises a reciprocal, reactive, two-way power splitter having an input connection connected to the transceiver device (10; 11; 12) and two output connections connected to one of the first antennas (16A, 16B; 17A, 17B; 18A, 18B).

3. The communication system according to claim 1, wherein: The coupling device (13; 14; 15) has a reciprocal two-way power splitter and two reciprocal two-way directional couplers (24; 25), wherein the input connection parts of the directional couplers (24; 25) are respectively connected to one of the first antennas (16A, 16B; 17A, 17B; 18A, 18B), the output connection parts of each directional coupler (24; 25) are respectively connected to the corresponding output connection parts of the other directional coupler (25; 24), the other output connection part of each directional coupler (24; 25) is respectively connected to one of the output connection parts of the two-way power splitter, and the input connection parts of the two-way power splitter are connected to the transmitting and receiving device (10; 11; 12).

4. The communication system according to claim 3, wherein: The two-way power splitter is a Wilkinson power splitter.

5. The communication system according to claim 3 or 4, characterized in that Two two-way directional couplers (24; 25) connected to each other at output connections (B2; C2) form a structural unit (27) having four external connections.

6. The communication system according to claim 2, wherein: The two-way power divider is symmetrical.

7. The communication system according to claim 3, wherein: The two-way power divider is symmetrical.

8. The communication system according to claim 1, wherein: The coupling device (13; 14; 15) comprises a reciprocal two-way tap (28) having a branch connection (E1) connected to the transceiver device (10; 11; 12) and two through connections (E2, E3), wherein the branch connection (E1) is connected to the transceiver device (10; 11; 12) and the through connections (E2, E3) are respectively connected to one of the first antennas (16A, 16B; 17A, 17B; 18A, 18B).

9. The communication system according to claim 8, wherein: The two-way tap (28) is symmetrical.

10. The communication system according to any one of claims 1 to 3, characterized in that: The slot waveguide (1) has a plurality of sections (1A; 1B; 1C; 1D) separated from each other by gaps (7; 8; 9), and is provided with a plurality of transmitting and receiving devices (10; 11; 12) of a stationary base station (6), wherein each transmitting and receiving device is connected to two first antennas (16A, 16B; 17A, 17B; 18A, 18B) extending into different sections (1A; 1B; 1C; 1D) of the slot waveguide (1) via a coupling device (13; 14; 15) assigned thereto.

11. The communication system according to claim 10, wherein: Different transceiver devices (10; 11; 12) of the stationary base station (6) communicate with the transceiver device (19; 20) of the vehicle (4; 5) at least partially via different channels.

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