COMMUNICATION NETWORK AND METHOD FOR OPERATING A COMMUNICATION NETWORK

Description

[0001] The invention relates to a communication network, in particular an ad-hoc communication network, with at least one mobile radio device and with a plurality of further radio devices installed along a route of the mobile radio device, which are hereinafter referred to as route-side radio devices.

[0002] From US patent 4,209,749 A, a communication network of this type is known, in which each of the additional radio devices is configured to use a radio channel pair in each of the two directions of the link for communication with one of the other additional radio devices, namely with the other additional radio device adjacent in the respective direction. Here, two relay stations and a main station located between them form each transmission segment, with the transitions between adjacent transmission segments being formed by further relay stations. Mutual decoupling of successive transmission segments along the link is achieved by alternating two frequency pairs from transmission segment to transmission segment.The at least one mobile radio device has a frequency switching device for automatic frequency pair switching when transitioning to the next transmission segment.

[0003] Furthermore, a generic communication network, designed as an ad-hoc communication network, is known from US document 2008 / 095134 A1. Signal transmission occurs via individual communication channels, such as individual physical radio links. Roadside units, for example, communicate with each other via a dedicated RR channel. Several alternatives are provided for channel allocation between vehicle-to-vehicle (VV) channels and vehicle-to-roadside (VR) channels.

[0004] In the publication DE 10 2017 203 040 A1, a communication network with the features of the preamble of patent claim 1 is described.

[0005] The Figure 1Figure 1 also shows a communication network KN* in the form of an ad-hoc communication network with a mobile radio unit FT* and with a plurality of further radio units Fi* installed along a track, which are hereinafter also referred to as nodes. A communication participant, in particular a vehicle-side control unit TC*, is connected to the mobile radio unit FT*, which is installed in a track-bound vehicle in the form of a train T. The in Figure 1The communication network KN* shown also includes another radio unit FTCC*, to which another communication participant is connected. This other communication participant is a trackside control and management unit TCC* in the form of a so-called Traffic Control Center. The mobile radio unit FT* is located at the left end of a chain K* formed by four other radio units. The other radio unit FTCC* is located at the right end of this chain K*. Therefore, the mobile radio unit FT* and the other radio unit FTCC* are subsequently referred to as side-mounted radio units. If the mobile radio unit FT*, which is appropriately connected to the vehicle-side control and management unit TC* for data transmission, transmits data provided by the vehicle-side control and management unit in the form of data packets, these are forwarded via the nodes Fi*.The data is therefore transmitted via chain K* to the other radio equipment FTTC* and is thus available to the Traffic Control Center TCC*, which is connected to the other radio equipment in a suitable manner for data transmission.

[0006] Each of the additional radio devices Fi* – that is, each of the nodes K* – is equipped with three radios, each operating on different frequencies, thus using different radio channels K1*, K2*, and K3*. This is shown in the Figure 1 The three frequencies or radio channels K1*, K2*, and K3* are indicated by dotted lines, dashed lines, and dash-dotted lines. These three frequencies or channels are then used alternately in the subsequent nodes. This introduces a specific frequency separation that minimizes interference.

[0007] Two of the three radios, hereinafter also referred to as side-mounted radios, are each configured as transmit and receive units (SE*) suitable for bidirectional communication by using a laterally mounted directional antenna. To introduce redundancy, a side-mounted radio (SE*) of a node transmits not only to the immediately adjacent node but also to the node following it. The third radio, located above, is configured as a receive unit (E*) suitable for receiving data packets from the directly adjacent nodes—from both directions R1* and R2* of the link—by being equipped with an omnidirectional antenna.

[0008] When a node Fi* receives a data packet from another node on any of the three radios, it forwards the data packet to the adjacent node and the node immediately following it—that is, to the next and the node after that. It therefore forwards the data packet in the same direction, since data packets forwarded from a node in a specific direction to the next or subsequent node are marked with additional information that allows the receiving node to recognize that it must forward the data packet in that specific direction.

[0009] Unlike the nodes of chain K*, the two side radio units – the mobile radio unit FT* and the other radio unit FTCC* – are each equipped with three radios. Each radio unit is configured as a transmit / receive unit SE1*, SE2*, or SE3*, respectively, with an omnidirectional antenna to utilize the three radio channels for both receiving and transmitting data – in all directions. This ensures that the train's onboard control unit TC* is always able to communicate with any of the nodes Fi* in chain K*, regardless of the orientation of the respective node's antennas relative to the antennas of the train's mobile radio unit FT*.

[0010] However, a performance evaluation of this communication network KN*, which was carried out using computer simulations of various scenarios, has shown that in this communication network, transmissions from the mobile radio device FT* interfere with the transmissions of the 1 to 3 nodes of the chain K* that are nearest to it (as can be seen in Figure 1 , at the second node, to whose third radio unit is located at the top – i.e., on the same radio channel K2* – the data packets are transmitted from both the mobile radio unit FT* and the first node). The interference occurring during these transmissions leads to a loss of data packets. In the case of the Figure 2In the scenario shown, with a mobile radio unit FT* of a train T*, another radio unit FTCC* of a trackside control and monitoring unit TCC*, and a chain K* of 20 nodes, the interference, according to the computer simulations used, leads to a loss of data packets of 5.63%. Computer simulations of other scenarios with two mobile radio units (2-train scenarios) showed data packet losses of up to 20%.

[0011] In Figure 2The y-axis of the diagram represents the number of received data packets as a percentage of the original sent data packets. Since a node forwards a data packet to the next node and then to the node after that, a given node should ideally receive two copies of a data packet, i.e., 200% of the total packets received. The upper line shows the percentage of data packets received without errors. Similarly, the lower line shows the percentage of data packets received with errors.

[0012] The invention is based on the objective of creating a communication network with no or minimal data packet loss.

[0013] This task is solved with a communication network according to claim 1.

[0014] As will be shown later, computer simulations have revealed that with this type of communication network design, data packet losses are very low.

[0015] By designing the trackside radio equipment in such a way that three successive trackside radio equipment units alternately use the three radio channels, the so-called "hidden node problem" can be solved particularly well.

[0016] The mobile radio device can be used to connect a communication participant, in particular a vehicle-side control and steering unit, which is installed in a vehicle, especially a track-bound vehicle.

[0017] Furthermore, at least one other communication participant, in particular a trackside control and monitoring unit, may be connected to one of the trackside radio devices or to another radio device.

[0018] It is considered advantageous if the other radio device contains a receiving unit for each of the three radio channels and is configured to use the three radio channels exclusively for receiving data, namely for receiving data from the trackside radio devices; the other radio device contains a transmitting unit which is configured to use the additional fourth radio channel exclusively for sending data, namely for sending data to the trackside radio devices; and the respective second receiving unit of the trackside radio devices is configured to also use the additional fourth radio channel for receiving data from the other radio device.

[0019] The invention also relates to a method for operating a communication network according to claim 5.

[0020] With regard to the advantages of the method according to the invention, reference should be made to the advantages of the communication network according to the invention, since the advantages of the method according to the invention essentially correspond to the advantages of the communication network according to the invention.

[0021] It is considered advantageous if a communication participant, in particular a vehicle-side control and monitoring unit, is connected to the mobile radio device and is installed in a vehicle, in particular a track-bound vehicle.

[0022] At least one other communication participant, in particular a trackside control and monitoring unit, can advantageously be connected to one of the trackside radio devices or to another radio device.

[0023] It is considered advantageous if The other radio device contains a receiver unit for each of the three radio channels and uses the three radio channels exclusively for receiving data, namely for receiving data from the trackside radio devices; the other radio device contains a transmitter unit that uses the additional fourth radio channel exclusively for sending data, namely for sending data to the trackside radio devices; and the respective second receiver unit of the trackside radio devices also uses the additional fourth radio channel for receiving data from the other radio device.

[0024] The invention is further described by reference to the Figures 3 to 5 explained in more detail. This will show that Figure 3 shows a section of a communication network according to the invention with a mobile radio device, another radio device and a plurality of further radio devices which form a chain of nodes, Figure 4 shows a section of the chain made up of Figure 3 with five neighboring additional radio devices and Figure 5 a result of a computer simulation which was carried out for a scenario of the communication network according to the invention.

[0025] The Figure 3 shows a communication network KN according to the invention without a network backbone, which is suitable for ensuring a continuous communication link between a mobile radio device FT of a communication participant TC and another radio device FTCC of another communication participant TCC.

[0026] The communication device TC shown here is installed in a vehicle – in this case, a track-bound vehicle in the form of a train T. The communication device TC is a vehicle-mounted control unit that can provide data packets to be sent to the mobile radio device FT via the connection shown, and can also receive data packets from this mobile radio device.

[0027] The other communication participant TCC shown here is a trackside control unit. This unit could be connected to one of the other radio units Fi* in a suitable data-transmitting manner to provide data packets for transmission and to receive data packets. However, in the communication network KN shown, the trackside control unit TCC is connected to the other radio unit FTCC via a suitable data-transmitting connection to provide data packets for transmission to the other radio unit FTCC and to receive data packets received from the other radio unit FTCC.

[0028] The depicted section of the communication network KN shows eight of the majority m of further radio devices, namely a first F1, six consecutive Fk, Fk+1, Fk+2, Fk+3, Fk+4, Fk+5 and a last Fm.

[0029] Each of the further radio devices i=1,2,...,k,k+1,k+2,k+3,k+4,k+5,...,up to m is designed to use a radio channel pair A, B or C in each of the two directions R1 and R2 of the path S for communication with other further radio devices.

[0030] The radio channel pair designated A consists of radio channels K1 and K2. The radio channel pair designated B consists of radio channels K2 and K3. The radio channel pair C consists of radio channels K3 and K1.

[0031] The radio channel pairs A, B, and C are formed from the three radio channels K1, K2, and K3 in such a way that the radio channel pairs A and B, B and C, and C and A differ by one radio channel in each pair of the additional radio devices. Three consecutive additional radio devices use the three radio channels alternately.

[0032] The mobile radio equipment FT is designed to use all radio channels K1, K2, K3 of the radio channel pairs A, B and C exclusively for receiving data, especially from other radio equipment.

[0033] An additional radio channel, K4, is planned.

[0034] The mobile radio equipment FT is suitable for using the additional radio channel K4 exclusively for transmitting data, especially to the other radio equipment Fi.

[0035] The other radio equipment Fi is suitable for using the additional radio channel K4 exclusively for receiving data, especially from the mobile radio equipment FT.

[0036] Each radio device Fi has a receiver E for receiving data from the other radio devices directly adjacent to it, as well as two transmit and receive units SE, SE. Each of the two transmit and receive units SE, SE serves for bidirectional communication with one of the other radio devices that follows one of the directly adjacent other radio devices.

[0037] Here too, when a node Fi receives a data packet from another node on any of the three radios, it forwards this data packet to the neighboring node and the immediately following node – that is, to the next and the node after that. It therefore forwards the data packet in the same direction, since data packets forwarded from a node in a specific direction to the next or subsequent node are marked with additional information that allows the receiving node to recognize that it must forward the data packet in that specific direction.

[0038] Only one node, which receives a data packet from the mobile radio device, initially forwards the data packet in both directions R1 and R2 of the path (in the Figure 3(for example, node Fk+1). The same applies when a node receives a data packet from the other radio device.

[0039] Communication and data transmission takes place via the three different radio channels K1, K2, K3 in a spatially alternating pattern.

[0040] This pattern is illustrated below using the one in the Figure 4 The excerpt shown is explained.

[0041] The additional radio equipment Fk+1 is configured to receive data from the directly adjacent radio equipment Fk and Fk+2 via one of the three channels – namely channel K1, hereinafter also referred to as the first channel – using its receiver unit E. Channel K1 is represented by a dotted line.

[0042] The next radio station Fk+2 in the direction of R1 – i.e., adjacent to Fk+1 in the direction of R1 – is configured to receive data from its two directly adjacent trackside radio stations Fk+1 and Fk+3 via another of the three radio channels – namely channel K2, hereinafter also referred to as the second channel – using its receiver unit E. Channel K2 is always represented by a dashed line.

[0043] The next radio unit Fk+3, located in the direction of R1 – i.e., adjacent to Fk+2 in the direction of R1 – is configured to receive data from its two directly adjacent trackside radio units Fk+2 and Fk+4 via another of the three radio channels – namely channel K3, hereinafter also referred to as the third channel – using its receiver unit E. Channel K3 is always represented by a dashed line.

[0044] Repetitions of this pattern along the route S correspond to the further radio equipment Fk+4 following the further radio equipment Fk+3 in the direction of R1,

[0045] Data from their two directly adjacent trackside radio installations Fk+3 and Fk+5 (see Figure 4 ) to be received via the first channel K1 using their receiving unit E.

[0046] And the further radio equipment Fk, located upstream of the further radio equipment Fk+1 in the direction of R1 - i.e., adjacent in the direction of R2 - is equipped to receive data from its two directly adjacent trackside radio equipment Fk-1 (not shown) and Fk+1 via third channel K3 using its receiving unit E.

[0047] Each successive three of the additional radio devices, for example Fk, Fk+1 and Fk+2, use the three radio channels alternately.

[0048] In other words, data packets are forwarded unidirectionally along the route S in each direction by the other radio devices Fi using the three radio channels K1, K2 and K3 alternately.

[0049] According to Figure 4 The second radio unit, Fk+2, communicates bidirectionally with its next-but-one right neighbor, Fk+4, on the third channel, K3. Furthermore, it communicates bidirectionally with its next-but-one left neighbor, Fk, on the first channel, K1, and receives unidirectionally from its left and right immediate neighbors via the second channel, K2.

[0050] The additional radio device Fk+3 communicates bidirectionally with its next-but-one right neighbor Fk+5 on the first channel K1 and communicates bidirectionally with its next-but-one left neighbor Fk+1 on the second channel K2.

[0051] The additional radio device Fk+1 communicates bidirectionally with its next-but-one right neighbor Fk+3 on the second channel K2 and communicates bidirectionally with the next-but-one left neighbor Fk-1 (not shown) on the third channel K3.

[0052] In other words, each additional radio device Fi receives data from its directly neighboring additional radio devices on one of the three different channels, communicates bidirectionally with its next-but-one neighbor in a first direction along the route S on another of the three channels, and communicates with its next-but-one neighbor in a second direction opposite to the first direction on a last of the three channels.

[0053] In this multi-channel configuration, the three adjacent additional radio devices Fk, Fk+1, Fk+2 use the first radio channel K1, in such a way that the middle Fk+1 receives data packets exclusively on the first radio channel K1 and the two directly adjacent outer Fk and Fk+2 transmit data packets on this channel.

[0054] Only with the triplet Fk+3, Fk+4, Fk+5 do the two directly adjacent outer radio devices Fk+3 and Kk+5 again transmit data packets on this channel K1, with the middle radio device Fk+4 exclusively receiving data packets on channel K1.

[0055] This makes it easy to solve the hidden node problem.

[0056] In the communication network KN according to the invention, the additional radio channel K4, which is different from the three radio channels K1, K2 and K3, is used for communication from the mobile radio device FT of the train T to the chain K of the nodes formed by the further radio devices Fi - specifically for sending data packets to the chain K. The mobile radio device FT does not receive data packets on this channel K4.

[0057] For receiving data on the three radio channels K1, K2, and K3, the FT mobile radio device has three receiving units E1, E2, and E3, each with an omnidirectional antenna. The first receiving unit, E1, receives data packets on the first channel, K1. The second receiving unit, E2, receives data packets on the second channel, K2. And the third receiving unit, E3, receives data packets on the third channel, K3.

[0058] The mobile radio device is additionally equipped with a transmitter unit S4 with an omnidirectional antenna, which is tuned to an additional frequency – i.e., it uses the additional radio channel K4. The mobile radio device uses this additional radio channel K4 exclusively for sending data packets, not for receiving them.

[0059] In this way, the transmissions from the mobile radio equipment FT of train T do not interfere with the transmissions from the nodes Fi of the chain.

[0060] Each of the additional radio equipment Fi – that is, each node in the chain K – is equipped with an additional receiving unit E4, which is tuned to an additional frequency in order to use the additional radio channel K4 exclusively for receiving data packets. In each node Fi of the chain, the respective additional receiving unit E4 is therefore used only for receiving, in particular data packets, from the mobile radio equipment FT.

[0061] In the communication network shown, the other radio device, FTCC, also has three receiving units, E1, E2, and E3, each with an omnidirectional antenna, for receiving data on the three radio channels K1, K2, and K3. The first receiving unit, E1, receives data packets on the first channel, K1. The second receiving unit, E2, receives data packets on the second channel, K2. And the third receiving unit, E3, receives data packets on the third channel, K3.

[0062] The other radio unit, FTCC, is additionally equipped with a transmitter unit S4 with an omnidirectional antenna, which is tuned to the additional frequency – thus also using the additional radio channel K4. This other radio unit uses this additional radio channel K4 exclusively for sending data packets, not for receiving them.

[0063] In each node Fi of the chain, the respective additional receiving device E4 is also used to receive data packets from the other radio device FTCC.

[0064] Figure 5 shows the results of a computer simulation, which led to a scenario of the one described in the Figure 3 The communication network shown was carried out.

[0065] As with the computer simulation, the results of which are presented in the Figure 2As shown, a scenario with a mobile radio device FT of a train, another radio device FTCC and a chain K of 20 nodes Fi was also chosen for the computer simulation of the communication network according to the invention.

[0066] It is evident that the disturbances which occur in the Figure 1 the communication network shown occurs in which the communication network according to the invention occurs Figure 3 are very effectively eliminated. The in Figure 5 Detectable data packet losses are in comparison to Figure 2 fell to 0.4%.

[0067] The communication network KN could, for example, be a WLAN (Wireless Area Network) or Wi-Fi according to the IEEE 802.11 standard family. Here, the 802.11p standard could be used for communication between the train T and the other radio equipment Fi, and one or more of the 802.11abg / 802.11n / 802.11ac standards for communication between the other radio equipment Fi. Alternatively, communication between the train T and the track or the other radio equipment Fi could also take place according to the LTE (Long Term Evolution) mobile communication standard, and communication between the trackside components or network nodes could be via WLAN or Wi-Fi.

[0068] The additional radio channel K4 thus represents a dedicated radio channel (dedicated frequency) for, in particular, trains in a communication network, especially an ad-hoc communication network for continuous communication between the trains and trackside infrastructure.

Claims

1. Communication network (KN), in particular an ad-hoc communication network, having at least one mobile wireless facility (FT) and having a plurality (m) of further wireless facilities (Fi, ..., Fm) that are installed on a travel route (S) of the mobile wireless facility (FT), which are referred to below as track-side wireless facilities (Fi, ..., Fm), wherein - the track-side wireless facilities are arranged such that at least two other track-side wireless facilities are located in both directions (R1, R2) along the travel route (S) in radio range of each of the track-side wireless facilities, - a respective wireless facility (Fi) of the track-side wireless facilities is configured in a suitable manner so as to use respectively a wireless channel pair (A or B or C) in each of the two directions (R1, R2) of the travel route (S) for communicating with other wireless facilities of the further wireless facilities, - the wireless channel pairs (A, B, C) are formed from three different wireless channels (K1, K2, K3) in such a manner that the two wireless channel pairs (A and B, B and C or C and A) of a respective wireless facility (Fi) of the track-side wireless facilities (F1, ..., Fm) differ with respect to a wireless channel, and - a respective three successive wireless facilities (Fk, Fk+1, Fk+2) of the track-side wireless facilities are configured such that they use the three different wireless channels in an alternating manner, in that a respective wireless facility (Fi) of the track-side wireless facilities has a first receiving unit (E) as well as two transmitting and receiving units and, by means of the first receiving unit (E), receives data from the track-side wireless facilities directly adjacent thereto on one of the three different wireless channels, by means of a first of the two transmitting and receiving units, communicates in a bidirectional manner with the next-but-one track-side wireless facility and communicates in a unidirectional manner with the next track-side wireless facility in a first of the two directions along the travel route (S) on one other of the three wireless channels and, by means of a second of the two transmitting and receiving units, communicates in a bidirectional manner with the next-but-one track-side wireless facility and communicates in a unidirectional manner with the next track-side wireless facility in the second direction which is opposite the first direction on a last of the three wireless channels, wherein each of the two transmitting and receiving units (SE) are configured to forward the data received by one of the track-side wireless facilities to the next and next-but-one track-side wireless facility in the same direction, - the mobile wireless facility (FT) for each of the three wireless channels (K1, K2, K3) contains a receiving unit (E1, E2, E3) in each case and is configured to use the three wireless channels exclusively for receiving data, namely for receiving data from the track-side wireless facilities, - an additional wireless channel (K4) is provided which is different from the three wireless channels (K1, K2, K3), - the mobile wireless facility (FT) contains a transmitting unit (S4) which is designed to use the additional fourth wireless channel (K4) exclusively for transmitting data, namely for transmitting data to the track-side wireless facilities (F1, ..., Fm), and - the track-side wireless facilities (F1, ..., Fm) each contain a second receiving unit (E4), which is designed in each case to use the additional fourth wireless channel (K4) exclusively for receiving data, namely for receiving data from the mobile wireless facility (FT).

2. Communication network (KN) according to claim 1, characterised in that a communication participant (TC), in particular a vehicle-side monitoring and control unit, is connected to the mobile wireless facility (FT), said communication participant being installed in a vehicle (T), in particular in a rail-born vehicle.

3. Communication network (KN) according to one of claims 1 or 2, characterised in that at least one other communication participant (TCC), in particular a track-side monitoring and control unit, is connected to one of the track-side wireless facilities (Fi) or to another wireless facility (FTCC).

4. Communication network (KN) according to claim 3, characterised in that - the other wireless facility (FTCC) contains a receiving unit (E1, E2, E3) for each of the three wireless channels (K1, K2, K3) and is configured to use the three wireless channels exclusively for receiving data, namely for receiving data from the track-side wireless facilities, - the other wireless facility (FTCC) contains a transmitting unit (S4) which is designed to use the additional fourth wireless channel (K4) exclusively for forwarding data, namely for forwarding data to the track-side wireless facilities (F1, ..., Fm), and - the respective second receiving unit (E4) of the track-side wireless facilities (F1, ..., Fm) is configured in each case to use the additional fourth wireless channel (K4) also for receiving data from the other wireless facility (FTCC).

5. Method for operating a communication network (KN), in particular an ad-hoc communication network, which is provided with at least one mobile wireless facility (FT) and with a plurality (m) of further wireless facilities (F1, ..., Fm) that are installed on a travel route (S) of the mobile wireless facility, which are referred to below as track-side wireless facilities (F1, ..., Fm), wherein - the track-side wireless facilities are arranged such that at least two other track-side wireless facilities are located in both directions (R1, R2) along the travel route (S) in radio range of each of the track-side wireless facilities, - a respective wireless facility of the track-side wireless facilities (F1, ..., Fm) uses one wireless channel pair (A or B or C) in each of the two directions (R1, R2) of the travel route (S) in each case for communicating with other of the further wireless facilities (F1, ..., Fm), - the wireless channel pairs (A, B, C) are formed from three different wireless channels (K1, K2, K3) in such a manner that the two wireless channel pairs (A and B, B and C or C and A) of a respective wireless facility (Fi) of the track-side wireless facilities differ with respect to a wireless channel, and - a respective three successive wireless facilities (Fk, Fk+1, Fk+2) of the track-side wireless facilities of the track-side wireless facilities are configured such that they use the three different wireless channels in an alternating manner, in that a respective one (Fi) of the track-side wireless facilities has a first receiving unit (E) as well as two transmitting and receiving units and, by means of the first receiving unit (E), receives data from the track-side wireless facilities directly adjacent thereto on one of the three different wireless channels, by means of a first of the two transmitting and receiving units, communicates in a bidirectional manner with the next-but-one track-side wireless facility and communicates in a unidirectional manner with the next track-side wireless facility in a first of the two directions along the travel route (S) on another of the three wireless channels and, by means of a second of the two transmitting and receiving units, communicates in a bidirectional manner with the next-but-one track-side wireless facility and communicates in a unidirectional manner with the next track-side wireless facility in the second direction which is opposite the first direction on a last of the three wireless channels, wherein each of the two transmitting and receiving units (SE) forwards the data received by one of the track-side wireless facilities to the next and next-but-one track-side wireless facility in the same direction, - the mobile wireless facility (FT) for each of the three wireless channels (K1, K2, K3) contains a receiving unit (E1, E2, E3) in each case and uses the three wireless channels exclusively for receiving data, namely for receiving data from the track-side wireless facilities, - an additional wireless channel (K4) is provided which is different from the three wireless channels (K1, K2, K3), - the mobile wireless facility (FT) contains a transmitting unit (S4) which uses the additional fourth wireless channel (K4) exclusively for transmitting data, namely for transmitting data to the track-side wireless facilities (F1, ..., Fm), and - the track-side wireless facilities (F1, ..., Fm) contain a second receiving unit (E4) in each case, which uses the additional fourth wireless channel (K4) exclusively for receiving data, namely for receiving data from the mobile wireless facility (FT).

6. Method according to claim 5, characterised in that a communication participant (TC), in particular a vehicle-side monitoring and control unit, is connected to the mobile wireless facility (FT), said communication participant being installed in a vehicle (T) in particular in a rail-born vehicle.

7. Method according to one of claims 5 or 6, characterised in that at least one other communication participant (TCC), in particular a track-side monitoring and control unit, is connected to one (Fi) of the track-side wireless facilities (F1, ...,Fm) or to another wireless facility (FTCC).

8. Method according to claim 7, characterised in that - the other wireless facility (FTCC) contains a receiving unit (E1, E2, E3) for each of the three wireless channels (K1, K2, K3) in each case and uses the three wireless channels exclusively for receiving data, namely for receiving data from the track-side wireless facilities, - the other wireless facility (FTCC) contains a transmitting unit (S4), which uses the additional fourth wireless channel (K4) exclusively for forwarding data, namely for forwarding data to the track-side wireless facilities (F1, ..., Fm), and - the respective second receiving unit (E4) of the track-side wireless facilities (F1, ..., Fm) use the additional fourth wireless channel (K4) in each case also for receiving data from the other wireless facility (FTCC).