CN109842464B - Method, system and device for retransmitting data packet - Google Patents
Method, system and device for retransmitting data packet Download PDFInfo
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- CN109842464B CN109842464B CN201710944656.2A CN201710944656A CN109842464B CN 109842464 B CN109842464 B CN 109842464B CN 201710944656 A CN201710944656 A CN 201710944656A CN 109842464 B CN109842464 B CN 109842464B
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Abstract
The invention discloses a method, a device and a system for retransmitting data packets, wherein in the setting stage, the information of the wireless link quality of each monitoring position is acquired and obtained at each monitoring position on the running route of a train and is stored in a train unit; in the running stage, monitoring the running position of the train on a running route, determining the retransmission times of the data packet at the monitoring position when the running distance of the train is a preset distance before the monitoring position, and determining the information according to the stored wireless link quality at the monitoring position; and when the train runs to the monitoring position, retransmitting the data packet according to the determined data packet retransmission times of the monitoring position. The monitoring position is provided in plurality on the train running route. The wireless train control system adaptively and dynamically sets the times of retransmitting the data packets according to different monitoring positions of each train in operation, retransmits the data packets, ensures the robustness of the wireless train control system and improves the transmission efficiency of the wireless train control system.
Description
Technical Field
The present invention relates to communications technologies, and in particular, to a method, a system, and an apparatus for retransmitting a data packet.
Background
A solution to train control such as subway trains is to build a wireless train control system. As shown in fig. 1, fig. 1 is a schematic structural diagram of a wireless train control system provided in the prior art. The network side of the wireless Train control system 10 is a backbone network 101 of a redundant ethernet, a plurality of wireless Access Points (AP)102 are arranged along a wireless Train, the AP102 is accessed to a central processing unit or a router in the backbone network, the AP102 is used as an interface of the wireless Train control system, and can be accessed to the backbone network through Train Units (TU, Train Units)103 arranged in the AP102 Train for transmitting data packets, the data packets are transmitted in a wireless signaling manner, so as to realize the control of the backbone network 101 on the wireless Train, and the Train Units 103 are wireless devices.
Four train units are arranged at the front end and the rear end of the train respectively and are used for transmitting data packets between the backbone network and the same time. And in the process of running the train along the line, data packets are transmitted between the AP points arranged in different areas of the route and the backbone network.
The wireless train control system maintains a plurality of wireless links for one train at the same time, which puts requirements on the robustness and stability of the wireless train control system. In order to ensure the robustness of the wireless train control system, the data packet needs to be retransmitted for multiple times, which is currently realized in a static setting mode and is not changed during the running period of the train, that is, the retransmission times of the data packet are preset, and the retransmission is performed according to the preset retransmission times of the data packet when the train runs. During static configuration, the retransmission times of the configured data packets compromise the transmission efficiency and robustness of the wireless train control system at the same time: if the set number of retransmissions is large, the retransmission of a large number of packets will increase interference and delay within the wireless train control system, while if the set number of retransmissions is small, robustness to external interference or suboptimal radio coverage conditions is reduced.
Disclosure of Invention
In view of the above, the present invention provides a method for retransmitting a data packet, which is capable of adaptively and dynamically setting the number of times of retransmitting the data packet to perform retransmission of the data packet.
The invention also provides a device for retransmitting the data packet, which can adaptively and dynamically set the times of retransmitting the data packet to retransmit the data packet.
The invention also provides a system for retransmitting the data packet, which can adaptively and dynamically set the times of retransmitting the data packet to retransmit the data packet.
The invention is realized by the following steps:
the present invention includes a method for retransmitting a data packet, comprising:
monitoring the arrival position of a train during the operation of the train;
predicting a wireless link quality of said train at a second location;
when the train reaches a first position, determining the retransmission times of the data packets of the train at the second position according to the predicted wireless link quality of the train at the second position, wherein the train reaches the first position firstly and then reaches the second position;
when the train reaches the second position, the train is controlled to transmit the data packets according to the determined retransmission times of the data packets, so that the retransmission times of the data packets are dynamically set according to the wireless link quality information of the monitored area, and the stability and the robustness of the wireless train control system are improved.
The method further comprises the following steps: when the train runs to the second position in the past, acquiring and storing the information of the quality of the wireless link of the train at the second position;
predicting a wireless link quality of said train at a second location, comprising: and predicting the wireless link quality of the train at the second position according to the information which is collected and stored in advance. Therefore, the collection of the wireless link quality information is completed in the previous time period, and the calculation time when the retransmission times are determined at this time is not occupied, so that the processing is faster.
Preferably, predicting the wireless link quality of the train at the second position according to pre-collected and stored information of the wireless link quality of the train at the second position comprises:
predicting the wireless link quality of the train at the second position according to the information of the wireless link quality of the train at the second position, which is collected and stored when the train reaches the second position in the last running process; or
And after different weighted values are respectively set for the acquired and stored information of the quality of at least two wireless links of the train at the second position when the train reaches the second position in the running process of the previous set times, calculating by adopting a weighted average algorithm to obtain the information of the quality of the wireless links of the train at the second position. Therefore, the collected wireless link information is updated in different modes, and the accuracy of the collected wireless link information is ensured.
The present invention also includes a method for retransmitting a data packet, comprising:
determining the retransmission times of a data packet sent when passing through an Access Point (AP) in the running process of a train;
and determining the retransmission times of the data packets sent to the train by the AP when the train passes through the AP according to the determined retransmission times of the data packets sent by the train when the train passes through the AP. Therefore, the data packet is sent to the train at the AP, the retransmission times of the data packet determined and obtained at the train end can be referred, the processing is simple, and the system stability is improved.
The present invention includes an apparatus for retransmitting a data packet, comprising: a prediction unit, a positioning unit, an operation unit and an execution unit, wherein,
the prediction unit is used for predicting the wireless link quality of the train at a second position;
the positioning unit is used for monitoring the arrival position of a train in the running process of the train and sending a first notice to the arithmetic unit when the train arrives at a first position; sending a second notification to the execution unit when the train reaches a second location; the operation unit is used for determining the retransmission times of the data packets of the train at the second position according to the predicted wireless link quality of the train at the second position when receiving a first notice, wherein the train arrives at the first position firstly and then arrives at the second position, and the determined retransmission times of the data packets are sent to the execution unit; and the execution unit is used for indicating the train to transmit the data packet according to the retransmission times of the data packet determined by the operation unit according to the second notification. Therefore, the dynamic setting of the times of retransmitting the data packets is realized, and the stability and the robustness of the wireless train control system are improved according to the wireless link quality information of the monitored area.
Preferably, the method further comprises the following steps: a collecting unit and a storage unit, wherein,
the positioning unit is further used for sending a third notice to the acquisition unit when the train runs to the second position in the past;
the acquisition unit is used for acquiring the information of the quality of the wireless link of the train at the second position according to the third notice and sending the information to the storage unit;
the storage unit is used for storing the information of the wireless link quality of the train at the second position, which is acquired by the acquisition unit. Therefore, the collection of the wireless link quality information is completed in the previous time period, and the calculation time when the retransmission times are determined at this time is not occupied, so that the processing is faster.
Preferably, the apparatus further comprises:
the prediction unit is further configured to,
predicting the wireless link quality of the train at the second position only according to the information of the wireless link quality of the train at the second position, which is stored in the storage unit and acquired and stored when the train reaches the second position in the last running process; or
And after different weighted values are respectively set for the information of the quality of at least two wireless links of the train at the second position, which is acquired and stored by the storage unit when the train reaches the second position in the running process of the preset times, the information of the quality of the wireless links of the train at the second position is obtained after calculation by adopting a weighted average algorithm. Therefore, the collected wireless link information is updated in different modes, and the accuracy of the collected wireless link information is ensured.
The invention also discloses a device for retransmitting the data packet, which comprises: the system comprises a position unit, a determination unit and a retransmission unit, wherein the position unit is used for positioning a train to pass a second position in the running process; the determining unit is used for determining the retransmission times of the data packets sent by the train according to the determined retransmission times of the data packets sent by the train when the train passes through the second position; and the retransmission unit is used for transmitting the data packet by adopting the retransmission times of the data packet transmitted by the train. Therefore, the data packet is sent to the train at the AP, the retransmission times of the data packet determined and obtained at the train end can be referred, the processing is simple, and the system stability is improved.
The invention also provides a train, which comprises the device for retransmitting the data packet. The train can dynamically set the times of retransmitting data packets according to the quality of a wireless link in a monitored area, so that the stability and the robustness of a wireless train control system are improved.
The present invention also provides a system for retransmitting data packets, comprising: a device for retransmitting data packets, a plurality of APs to which the second location belongs, and a wireless train control system network side unit, wherein,
the device for retransmitting the data packet is used for monitoring the arrival position of a train in the running process of the train; predicting a wireless link quality of said train at a second location; when the train reaches a first position, determining the retransmission times of the data packets of the train at the second position according to the predicted wireless link quality of the train at the second position, wherein the train reaches the first position firstly and then reaches the second position; when the train reaches the second position, controlling the train to transmit data packets to the plurality of APs according to the determined retransmission times of the data packets;
a plurality of APs to which the second location belongs, for transmitting the data packet received from the apparatus for retransmitting the data packet to the wireless train control system network side unit;
and the network side unit of the wireless train control system is used for receiving data packets sent by a plurality of APs to which the second position belongs. Thus, the provided system can dynamically set the retransmission data packet times according to the wireless link quality information of the monitored area, thereby improving the stability and robustness of the wireless train control system.
In the system, the plurality of APs to which the second location belongs are further configured to transmit the packet retransmission times of the packet by using the packet retransmission apparatus, and to transmit the packet retransmission times from the network side unit of the wireless train control system to the packet retransmission apparatus;
the means for retransmitting the data packet is further configured to receive data packets from a plurality of APs to which the second location belongs;
and the network side unit of the wireless train control system is also used for sending data packets to a plurality of APs to which the second positions belong. The apparatus for retransmitting a data packet is any of the apparatuses for retransmitting a data packet described above. The system sends the data packet to the train at the AP, and can also refer to the retransmission times of the data packet determined and obtained at the train end, so that the processing is simple and the system stability is improved.
The invention provides a device for retransmitting data packets, which comprises: at least one memory, at least one processor, and at least one wireless communication port, wherein:
the at least one memory for storing a computer program;
the at least one wireless communication port is used for transmitting and receiving data;
the at least one processor configured to invoke the computer program stored in the at least one memory to perform a method of retransmitting data packets as described in any one of the above based on the function of the at least one wireless communication port to transmit and receive data. Therefore, the dynamic setting of the times of retransmitting the data packets is realized, and the stability and the robustness of the wireless train control system are improved according to the wireless link quality information of the monitored area.
The present invention provides a machine-readable storage medium having machine-readable code stored thereon; the machine readable code is capable of being executed by a processor and implementing the above-described method for retransmitting data packets. The dynamic setting of the times of retransmitting the data packets is realized, and the wireless link quality information of the monitored area is obtained according to the times, so that the stability and the robustness of the wireless train control system are improved.
According to the scheme, in the setting stage, the method, the device and the system, the information of the wireless link quality of each monitoring position is acquired and stored at each monitoring position on the running route of a train; in the running stage, monitoring the running position of the train on a running route, determining the retransmission times of the data packet at the monitoring position when the running distance of the train is a preset distance before the monitoring position, and determining the information according to the stored wireless link quality at the monitoring position; and when the train runs to the monitoring position, retransmitting the data packet according to the determined data packet retransmission times of the monitoring position. The monitoring position is provided in plurality on the train operation line. Therefore, the wireless train control system adaptively and dynamically sets the times of retransmitting the data packets according to different monitoring positions of each train in operation, retransmits the data packets, ensures the robustness of the wireless train control system and improves the transmission efficiency of the wireless train control system.
Drawings
The foregoing and other features and advantages of the invention will become more apparent to those skilled in the art to which the invention relates upon consideration of the following detailed description of a preferred embodiment of the invention with reference to the accompanying drawings, in which:
FIG. 1 is a schematic diagram of a wireless train control system provided in the prior art;
fig. 2 is a flowchart of a method for retransmitting a data packet in a wireless train control system according to the present invention;
fig. 3 is a schematic structural diagram of an apparatus for retransmitting a data packet in a wireless train control system according to the present invention;
fig. 4 is a schematic structural diagram of a second apparatus for retransmitting a data packet in a wireless train control system according to the present invention;
fig. 5 is a schematic structural diagram of a system for retransmitting a data packet in a wireless train control system according to the present invention;
fig. 6 is a schematic diagram of a third structure of an apparatus for retransmitting a data packet in a wireless train control system according to the present invention.
Description of the reference numerals
| 201～204 | The steps involved in FIG. 2 |
| 301 | |
| 302 | |
| 303 | |
| 304 | |
| 305 | |
| 306 | |
| 401 | |
| 402 | Determining |
| 403 | |
| 501 | |
| 502 | Multiple access points to which the second location belongs |
| 503 | Wireless train control system |
| 601 | |
| 602 | Processor with a memory having a plurality of |
| 603 | Wireless communication port |
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail by referring to the following examples.
In order to ensure the robustness and stability of the wireless train control system, it is necessary not only to eliminate the failure of each constituent unit participating in the packet transmission, but also to eliminate the transmission interruption caused by relatively slow switching of APs transmitting packets while the train is moving from one AP jurisdiction to another AP jurisdiction. In this case, even if the wireless train control system has good radio coverage along the train, it is possible that at some point during the train operation, two train units in the train are involved in the process of transmitting data packets, while the other train units are engaged in the handoff process of the AP.
In order to ensure that the wireless train control system can receive the transmission data packet, i.e. to improve the redundancy of the wireless train control system, especially in the case that the transmission data packet is not ideal, for example, the suboptimal radio is covered along the train, or there is stronger radio interference along the train, the configurable parameters of the currently available wireless interface for retransmitting the data packet can be set,
in the background art, wireless train control systems have introduced the concept of air link (AIRLINK) retransmission. The AIRLINK retransmission differs from the packet retransmission scheme based on the wireless lan, i.e. the automatic repeat request (ARQ) concept defined in the IEEE802.11 standard, and is retransmitted if an Acknowledgement (ACK) message is not received within a specified time window after the transmission of a packet. Because the train runs continuously along the line, different APs are accessed at different time points, the ARQ concept is adopted to retransmit the data packet, and the network side cannot receive the ACK message of the data packet, so the ARQ concept cannot be applied by the wireless train control system. The adopted mode of the AIRLINK retransmission is as follows: multiple identical copies of the packet, whether or not successfully transmitted, are transmitted on the set currently available AP. Here, the number of the multiple identical copies of the data packet may be configured, that is, the retransmission number of the data packet may be configured, but is statically configured and will not be changed during the operation of the wireless train control system. Because the retransmission times of the data packets are statically configured, the stability and robustness of the wireless train control system cannot be ensured.
In order to ensure the robustness of the wireless train control system and improve the transmission efficiency of the wireless train control system, the invention needs to accurately set the times of retransmitting the data packets by the wireless train control system. Therefore, the invention dynamically sets the retransmission times of the data packets at different monitoring positions on the running line aiming at the train, and the retransmission times can be updated in real time.
Specifically, in the setting stage, the wireless link quality information of each monitoring position is acquired and stored at each monitoring position on a train running route; in the running stage, monitoring the running position of the train on a running route, determining the retransmission times of the data packet at the monitoring position when the running distance of the train is a preset distance before the monitoring position, and determining the information according to the stored wireless link quality at the monitoring position; and when the train runs to the monitoring position, retransmitting the data packet according to the determined data packet retransmission times of the monitoring position. The monitoring position is provided in plurality on the train operation line.
Therefore, the wireless train control system adaptively and dynamically sets the times of retransmitting the data packets according to different monitoring positions of each train in operation, retransmits the data packets, ensures the robustness of the wireless train control system and improves the transmission efficiency of the wireless train control system.
Fig. 2 is a flowchart of a method for retransmitting a data packet in a wireless train control system according to the present invention, which includes the following steps:
and 204, when the train reaches the second position, controlling the train to transmit the data packets according to the determined retransmission times of the data packets.
In the method, the step 203 of determining the number of data packet retransmissions of the train at the second location when the train arrives at a first location is calculated on the running route between the arrival at a first location and the arrival at a second location.
In the method, the step 204 of transmitting the data packet is transmitting the data packet through at least one train unit on the train.
The method further comprises the following steps: when the train runs to the second position in the past, acquiring and storing the information of the quality of the wireless link of the train at the second position; at the time of acquisition, multiple acquisitions were made at different time points.
Predicting a wireless link quality of said train at a second location, comprising: and predicting the wireless link quality of the train at the second position according to the information which is acquired and stored in advance.
In the method, predicting the wireless link quality of the train at the second position according to the information of the wireless link quality of the train at the second position collected and stored in advance comprises the following steps:
predicting the wireless link quality of the train at the second position according to the information of the wireless link quality of the train at the second position, which is collected and stored when the train reaches the second position in the last running process; or
And after different weighted values are respectively set for the acquired and stored information of the quality of at least two wireless links of the train at the second position when the train reaches the second position in the running process of the preset times, calculating by adopting a weighted average algorithm to obtain and store the information of the quality of the wireless links of the train at the second position.
In the method, the process of monitoring the arrival position of the train, that is, the process of locating the train, may include various ways, such as:
arranging a plurality of transponders or sensors on the running route of the train;
receiving a response signal sent by the transponder or receiving a sensing signal sent by a sensor in the running process of the train;
calculating to obtain the running position of the train according to the received response information or sensing information and the acquired mileage counter value of the train, and determining the position where the train arrives according to the running position of the train;
or comprises the following steps: and in the running process of the train, performing information interaction with an access point AP to which the position where the train arrives belongs, and determining the position where the train arrives.
In the method, the information of the radio link quality comprises at least one of the following information:
collecting time parameters of the information of the wireless link quality;
location information of the second location;
the packet loss rate of the data packet is sent when the train is at the second position;
information of signal reception intensity of a wireless Access Point (AP) received by the train at the second position;
a data packet transmission rate of the train at the second location; and
a data packet transmission delay of the train at the second location.
In the method, the instructing the train to transmit the data packet according to the determined retransmission times of the data packet comprises the following steps: and indicating the train to transmit the data packets to the network side of the wireless train control system through the plurality of APs of the second position according to the determined retransmission times of the data packets.
In addition, the multiple APs to which the train belongs also retransmit the data packet to the train, and the specific process is as follows:
determining the retransmission times of a data packet sent when passing through an Access Point (AP) in the running process of a train;
and determining the retransmission times of the data packets sent to the train by the AP when the train passes through the AP according to the determined retransmission times of the data packets sent by the train when the train passes through the AP.
As an example, the radio link quality information for monitoring the train location can be obtained as follows:
in the first step, during the running process of the train, the monitoring position is located, and the reference of the location may be the AP to which the monitoring position belongs, or other set monitoring positions.
In this step, there are many kinds of monitoring position locations, such as:
in the first mode, a transponder is arranged at a monitoring position along the running line of a train, the transponder receives a response signal when the train passes through, and the position of the train is determined according to a mileage counter and the response signal arranged in the train, so that the monitoring position of the train is determined; of course, other sensors can be arranged on the monitoring of the running line of the train, a sensing signal is sent to the train when the train passes by, and the train determines the position of the train according to the arranged mileage counter and the sensing signal so as to determine which monitoring position the train is at;
in the second mode, the wireless train control system sends position information to train units in the train through the AP, and the train units in the train determine the monitoring position of the train through the position information interacted between the AP and the wireless train control system;
in a third mode, if the train is not currently accessed into the wireless train control system, the train unit of the train can also determine whether an accessible AP exists or not in the running process of the train, determine whether the AP can be accessed wirelessly or not, and determine the monitoring position of the train by adopting the passing affiliated AP jurisdiction.
Secondly, the current time, the monitoring position and the wireless link quality information of the monitoring position of the train are corresponded;
in this step, the current time includes a date and a time, and the wireless link quality information includes, but is not limited to, an acquisition time parameter, the second location information, a packet loss rate, a train wireless interface strength parameter, a packet transmission rate, and the like.
And thirdly, corresponding the current running time of the train, the monitoring position and the wireless link quality information of the monitoring position.
The storage mode may be storage using a log file, and of course, storage using other more suitable storage formats may also be stored in a storage unit provided in the train.
In the method, because the wireless train runs in the same time period of the same route every day or every few days, the acquisition process can be repeated in the same running time period of the train with different set dates, the newly acquired data is covered with the old acquired data, the old acquired information is discarded, and the acquired data is updated in real time.
That is, in the method, the stored radio link quality information of the monitoring location is: and on the running route, setting wireless link quality information of monitoring positions in different time periods. And updating according to the distance between the time period and the current time period, wherein the stored wireless link quality information is the wireless link quality information closest to the current time period.
In step 203 of the method, the determining process is:
and calculating the times of obtaining the retransmission data packet of the second position by adopting a set self-adaptive algorithm by taking the stored wireless link quality information of the second position as an input parameter so as to ensure the robustness of the wireless train control system and improve the transmission efficiency of the wireless train control system as a reference condition.
That is, the adaptive algorithm retrieves historical data of the wireless link quality information of each monitoring location stored on the train route, the historical data records the monitoring locations of the train, and mileage intervals are preset between the monitoring locations and can also be set based on the AP. The AP which the train passes through at the same monitoring position on the previous date. The adaptive algorithm is obtained by calculation based on the packet loss rate in historical data and the reliability of the wireless train control system transmission required by reducing the times of retransmitting data packets. This calculated number of retransmitted data packets is recalculated and updated in accordance with the update of the history data.
In addition, an AP in the wireless train control system may transmit a packet sent by the network side of the wireless train control system to a train unit of the train based on the retransmission number of the packet of the supervised monitoring location, and the AP determines the number of times of downlink retransmission of the packet according to the retransmission number of the packet transmitted by the train unit of the train.
Fig. 3 is a schematic structural diagram of an apparatus for retransmitting a data packet in a wireless train control system according to the present invention, which can perform the method shown in fig. 2. The apparatus may include: a prediction unit 301, a positioning unit 302, an arithmetic unit 303, and an execution unit 304, wherein,
the prediction unit 301 is configured to predict a radio link quality of the train at a second location;
the positioning unit 302 is configured to monitor an arrival position of a train during operation of the train, and send a first notification to the operation unit 303 when the train arrives at a first position; sending a second notification to the execution unit 304 when the train reaches a second location; the operation unit 303, configured to determine, when receiving a first notification, a number of data packet retransmissions of the train at the second location according to the predicted radio link quality of the train at the second location, where the train arrives at the first location first and then arrives at the second location, and send the determined number of data packet retransmissions to the execution unit 304; the executing unit 304 is configured to instruct, according to the second notification, a train unit in the train to transmit a data packet according to the number of times of retransmission of the data packet determined by the calculating unit 303.
In the apparatus, further comprising: an acquisition unit 305 and a storage unit 306, wherein,
the positioning unit 302 is further configured to send a third notification to the collecting unit 305 when the train has run to the second position in the past;
the acquiring unit 305 is configured to acquire, according to the third notification, information of the quality of the wireless link of the train at the second location, and send the information to the storage unit 306;
the storage unit 306 is configured to store the information of the radio link quality of the train at the second location, which is acquired by the acquisition unit 305.
In the apparatus, further comprising: the prediction unit 301 is further configured to,
predicting the wireless link quality of the train at the second position according to the information of the wireless link quality of the train at the second position, which is stored in the storage unit 306 and acquired and stored when the train reaches the second position in the last operation process; or
After different weighted values are respectively set for the information of the quality of at least two wireless links of the train at the second position, which is acquired and stored when the train reaches the second position in the running process of the preset times and stored in the storage unit 306, the information of the quality of the wireless links of the train at the second position is obtained after calculation by adopting a weighted average algorithm.
In the device, the positioning unit 302 receives response information or sensing information sent by a plurality of transponders or sensors arranged on a running route of the train in the running process of the train, calculates the running position of the train according to the received response information or sensing information and the obtained mileage counter value of the train, and determines the arriving position of the train according to the running position of the train; or in the running process of the train, performing information interaction with an access point AP to which the position where the train arrives belongs, and determining the position where the train arrives.
In this apparatus, the execution unit 304 instructs the train unit of the train to transmit the data packet to the network side of the wireless train control system via the plurality of APs to which the second location belongs according to the determined number of times of retransmission of the data packet, based on the second notification.
In the apparatus, the radio link quality information includes: and acquiring a time parameter, the second position information, the packet loss rate of the data packet, a train wireless interface strength parameter and a data packet transmission rate.
Other optional implementations of the apparatus may refer to fig. 2 and its corresponding description, which are not described herein again.
The present invention also includes an apparatus, which is an AP, as shown in fig. 4, including: a location unit 401, a determination unit 402 and a retransmission unit 403, wherein,
the position unit 401 is used for positioning a train passing a second position in the running process;
the determining unit 402 is configured to determine, according to the determined retransmission times of the data packets sent when the train passes through the second location, the retransmission times of the data packets sent by the train;
the retransmission unit 403 is configured to transmit the data packet by using the retransmission times of the data packet sent by the train.
The invention also includes a train comprising the apparatus for retransmitting data packets as described in figure 3.
Fig. 5 is a schematic structural diagram of a system for retransmitting a data packet in a wireless train control system according to the present invention, which includes: the method comprises the following steps: the method comprises the following steps: a device 501 for retransmitting packets, a plurality of APs 502 belonging to the second location, and a wireless train control system network side unit 503, wherein,
the device 501 for retransmitting data packets is used for monitoring the arrival position of a train in the running process of the train; predicting a radio link quality of said train at a second location; when the train reaches a first position, determining the retransmission times of the data packets of the train at the second position according to the predicted wireless link quality of the train at the second position, wherein the train reaches the first position firstly and then reaches the second position; when the train reaches the second position, controlling the train to transmit data packets to the plurality of APs 502 according to the determined retransmission times of the data packets;
a plurality of APs 502 belonging to the second location, configured to send the data packet received from the packet retransmission apparatus 501 to the wireless train control system network side unit 503;
the wireless train control system network side unit 503 is configured to receive data packets sent by a plurality of APs 502 to which the second location belongs.
In this system, the plurality of APs 502 to which the second location belongs are also configured to transmit the packet retransmission times of the packet by using the packet retransmission apparatus 501, and to transmit the packet retransmission times from the network side unit 503 of the wireless train control system to the packet retransmission apparatus 501;
the means for retransmitting a data packet 501 is further configured to receive data packets from a plurality of APs 502 to which the second location belongs;
the network side unit 503 of the wireless train control system is further configured to send a data packet to a plurality of APs 502 to which the second location belongs.
In this system, the apparatus 501 for retransmitting a packet is any apparatus for retransmitting a packet described in fig. 3.
The present invention further includes a device for retransmitting a data packet, as shown in fig. 6, fig. 6 is a schematic diagram of three structures of the device for retransmitting a data packet in a wireless train control system according to the present invention, including: at least one memory 601, at least one processor 602, and at least one wireless communication port 603, wherein:
the at least one memory 601 for storing a computer program;
the at least one wireless communication port 603 for transmitting and receiving data;
the at least one processor 602 is configured to invoke computer programs stored in the at least one memory 601 to perform the method for retransmitting data packets described in fig. 2 based on the function of the at least one wireless communication port 603 for transmitting and receiving data.
The invention also discloses a machine-readable storage medium having machine-readable code stored thereon; the machine readable code is capable of being executed by a processor and implementing a method for retransmitting data packets as described in figure 2.
The invention can predict whether the train has external strong interference at the monitoring position on the operation line, and adaptively selects high times of retransmitting the data packet according to the advance, thereby ensuring the stability of the wireless train control system for controlling the operation of the train.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (14)
1. A method for retransmitting packets, comprising:
monitoring the arrival position of a train during the operation of the train;
predicting a radio link quality of said train at a second location;
when the train reaches a first position, determining the retransmission times of the data packets of the train at the second position according to the predicted wireless link quality of the train at the second position, wherein the train reaches the first position firstly and then reaches the second position; wherein determining the number of data packet retransmissions for the train at the second location comprises: using the predicted wireless link quality information of the train at the second position as an input parameter to ensure the robustness of a wireless train control system and improve the transmission efficiency of the wireless train control system as a reference condition, and calculating the retransmission times of the data packet of the train at the second position by adopting a set self-adaptive algorithm; the self-adaptive algorithm calculates the retransmission times of the data packets based on the packet loss rate in the historical data of the wireless link quality information of each monitoring position and the reliability of the wireless train control system transmission required by reducing the retransmission times of the data packets;
and when the train reaches the second position, controlling the train to transmit the data packet according to the determined retransmission times of the data packet.
2. The method of claim 1,
the method further comprises the following steps: when the train runs to the second position in the past, acquiring and storing the information of the quality of the wireless link of the train at the second position;
predicting a wireless link quality of said train at a second location, comprising: and predicting the wireless link quality of the train at the second position according to the information which is collected and stored in advance.
3. The method of claim 2, wherein predicting the wireless link quality of the train at the second location based on pre-collecting and storing information of the wireless link quality of the train at the second location comprises:
predicting the wireless link quality of the train at the second position according to the information of the wireless link quality of the train at the second position, which is collected and stored when the train reaches the second position in the last running process; or
And after different weighted values are respectively set for the acquired and stored information of the quality of at least two wireless links of the train at the second position when the train reaches the second position in the running process of the preset times, calculating the information of the quality of the wireless links of the train at the second position by adopting a weighted average algorithm.
4. A method for retransmitting packets, comprising:
determining the retransmission times of a data packet sent when passing through an Access Point (AP) in the running process of a train;
determining the retransmission times of the data packets sent by the AP to the train when the train passes through the AP according to the determined retransmission times of the data packets sent by the train when the train passes through the AP;
wherein determining the number of retransmissions of a data packet sent by the train when passing through the AP comprises: using the predicted wireless link quality information of the train passing through the AP as an input parameter to ensure the robustness of a wireless train control system and improve the transmission efficiency of the wireless train control system as a reference condition, and calculating the retransmission times of a data packet sent by the train passing through the AP by adopting a set self-adaptive algorithm; the self-adaptive algorithm calculates the retransmission times of the data packets based on the packet loss rate in the historical data of the wireless link quality information of each monitoring position and the reliability of the wireless train control system transmission required by reducing the retransmission times of the data packets.
5. An apparatus for retransmitting packets, comprising: a prediction unit (301), a positioning unit (302), an arithmetic unit (303) and an execution unit (304),
-said prediction unit (301) for predicting a radio link quality of said train at a second location;
the positioning unit (302) is used for monitoring the arrival position of a train in the running process of the train, and sending a first notice to the arithmetic unit (303) when the train arrives at a first position; sending a second notification to said execution unit (304) when said train reaches a second location;
the operation unit (303) is configured to, when receiving a first notification, determine the number of retransmission times of the data packet of the train at the second location according to the predicted wireless link quality of the train at the second location, where the train arrives at the first location first and then arrives at the second location, and send the determined number of retransmission times of the data packet to an execution unit (304); wherein determining the number of data packet retransmissions for the train at the second location comprises: using the predicted wireless link quality information of the train at the second position as an input parameter to ensure the robustness of a wireless train control system and improve the transmission efficiency of the wireless train control system as a reference condition, and calculating to obtain the retransmission times of the data packet at the second position by adopting a set self-adaptive algorithm; the self-adaptive algorithm calculates the retransmission times of the data packets based on the packet loss rate in the historical data of the wireless link quality information of each monitoring position and the reliability of the wireless train control system transmission required by reducing the retransmission times of the data packets;
and the execution unit (304) is used for instructing the train to transmit the data packet according to the retransmission times of the data packet determined by the operation unit (303) according to the second notification.
6. The apparatus of claim 5, further comprising: an acquisition unit (305) and a storage unit (306), wherein,
the positioning unit (302) is further used for sending a third notice to the acquisition unit (305) when the train runs to the second position in the past;
the acquisition unit (305) is used for acquiring the information of the wireless link quality of the train at the second position according to the third notification and sending the information to the storage unit (306);
the storage unit (306) is used for storing the information of the wireless link quality of the train at the second position, which is acquired by the acquisition unit (305).
7. The apparatus of claim 6,
the prediction unit (301) is further configured to,
predicting the wireless link quality of the train at the second position only according to the information of the wireless link quality of the train at the second position, which is collected and stored when the train reaches the second position in the last operation process and stored in the storage unit (306); or
And after different weighted values are respectively set for the at least two pieces of wireless link quality information of the train at the second position, which are acquired and stored when the train reaches the second position in the running process of the preset times and stored in the storage unit (306), the wireless link quality information of the train at the second position is obtained after calculation by adopting a weighted average algorithm.
8. An apparatus for retransmitting packets, comprising: a location unit (401), a determination unit (402) and a retransmission unit (403), wherein,
the position unit (401) is used for positioning a train to pass a second position in the running process;
the determining unit (402) is configured to determine the retransmission times of the data packets sent by the train according to the determined retransmission times of the data packets sent by the train when the train passes through the second position; wherein determining the number of data packet retransmissions when the train passes the second location comprises: using the predicted wireless link quality information of the train at the second position as an input parameter to ensure the robustness of a wireless train control system and improve the transmission efficiency of the wireless train control system as a reference condition, and calculating the retransmission times of the data packet sent by the train by adopting a set self-adaptive algorithm; the self-adaptive algorithm calculates the retransmission times of the data packets based on the packet loss rate in the historical data of the wireless link quality information of each monitoring position and the reliability of the wireless train control system transmission required by reducing the retransmission times of the data packets;
and the retransmission unit (403) is used for transmitting the data packet by adopting the retransmission times of the data packet sent by the train.
9. A train comprising means for retransmitting data packets as claimed in any one of claims 5 to 7.
10. A system for retransmitting packets, comprising: a device (501) for retransmitting data packets, a plurality of Access Points (AP) (502) belonging to a second location, and a wireless train control system network side unit (503),
the device (501) for retransmitting the data packet is used for monitoring the arrival position of a train in the running process of the train; predicting a wireless link quality of said train at a second location; when the train reaches a first position, determining the retransmission times of the data packets of the train at the second position according to the predicted wireless link quality of the train at the second position, wherein the train reaches the first position firstly and then reaches the second position; when the train reaches the second position, controlling the train to transmit data packets to the plurality of APs (502) according to the determined retransmission times of the data packets; wherein determining the number of data packet retransmissions for the train at the second location comprises: using the predicted wireless link quality information of the train at the second position as an input parameter to ensure the robustness of a wireless train control system and improve the transmission efficiency of the wireless train control system as a reference condition, and calculating the retransmission times of the data packet of the train at the second position by adopting a set self-adaptive algorithm; the self-adaptive algorithm calculates the retransmission times of the data packets based on the packet loss rate in the historical data of the wireless link quality information of each monitoring position and the reliability of the wireless train control system transmission required by reducing the retransmission times of the data packets;
a plurality of APs (502) to which the second location belongs, for transmitting a packet received from the train system unit (501) to the wireless train control system network side unit (503);
and the wireless train control system network side unit (503) is used for receiving data packets sent by a plurality of APs (502) to which the second position belongs.
11. The system according to claim 10, wherein said plurality of APs (502) to which said second location belongs is further configured to transmit said means (501) for retransmitting packets from said wireless train control system network side unit (503) to said train system unit (501) using the number of packet retransmissions for packets transmitted by said train system unit (501);
the means (501) for retransmitting data packets is further configured to receive data packets from a plurality of APs (502) to which the second location belongs;
the wireless train control system network side unit (503) is further configured to send a data packet to a plurality of APs (502) to which the second location belongs.
12. The system according to claim 10 or 11, characterized in that said means (501) for retransmitting data packets is a means for retransmitting data packets according to any of claims 5 to 7.
13. An apparatus for retransmitting packets, comprising: at least one memory (601), at least one processor (602), and at least one wireless communication port (603), wherein:
the at least one memory (601) for storing a computer program;
the at least one wireless communication port (603) for transmitting and receiving data;
the at least one processor (602) configured to invoke a computer program stored in the at least one memory (601) to perform the method of retransmitting data packets according to any of claims 1 to 4 based on the function of the at least one wireless communication port (603) to transmit and receive data.
14. A machine-readable storage medium having machine-readable code stored thereon; machine readable code capable of being executed by a processor and implementing a method for retransmitting data packets according to any one of claims 1 to 4.
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