CN107204824B - Data transmission method and system for low-speed channel - Google Patents
Data transmission method and system for low-speed channel Download PDFInfo
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Abstract
The application provides a data transmission method for a low-speed channel, belongs to the field of data transmission, and solves the problem of unstable low-speed data transmission in the prior art, and the method comprises the following steps: sending a query signal, and receiving a response signal responding to the query signal from a signal end within a first preset time length; judging whether the slave signal end has data to be transmitted according to the response signal, and judging whether the master signal end has data to be transmitted according to the response signal; sending a synchronous signal, and distributing a serial number of a data transmission time slot for the signal end to be sent with data; and the signal end performs data transmission in the allocated serial number data transmission time slot. According to the embodiment of the application, the data transmission time slot is only allocated to the signal end to which the data is to be transmitted, so that the problem of data loss caused by collision in the data transmission process in the prior art is solved, and the stability of data transmission is effectively ensured.
Description
Technical Field
The present application relates to the field of data transmission, and in particular, to a data transmission method and system for a low-speed channel.
Background
With the development of wireless technology, the application of wireless transmission is more and more extensive, such as cellular mobile communication, wireless paging, mobile phone video and other applications. It is also increasingly common to utilize wireless communication technology to enable the distribution of stocks, geographical locations, public information, etc. within a wireless local area network. In modern warehousing, logistics and military wars, the data transmission between devices in a wireless local area network is more important to be realized by utilizing a wireless communication technology.
In the process of realizing communication between devices by utilizing a wireless communication technology, the speed, the accuracy and the stability of data transmission are the precondition of ensuring the normal work of a network-based system. Taking military wars as an example, the geographical position of a battlefield in the basic modern wars changes at any time, the terrain environment factors are uncertain, the army is fast and slow when maneuvering, the boundaries of the enemy and the my are fuzzy, no network infrastructure exists on the battlefield, and the tactical internet requires the realization of fast networking under the conditions, thereby ensuring that the network is unblocked at any time, commanding commands are transmitted in time, and voice data are transmitted safely and reliably. However, the wireless channel itself has the problems of low transmission rate, limited bandwidth, susceptibility to external environment interference, poor channel quality, and the like, which requires improvement of data transmission reliability and transmission efficiency between devices in the network.
In the prior art, each signal terminal transmits data in a network by using the same frequency, and when the conditions of poor wireless channel quality, large data burst amount and the like are met, the problems of data loss, errors and retransmission caused by data transmission conflict are easy to occur. Therefore, how to improve the stability of data transmission in a low-speed wireless channel with low bandwidth and low quality is a problem to be solved urgently.
Disclosure of Invention
The technical problem that this application will solve is: the data transmission method for the low-speed channel is provided, and the problem of poor data transmission stability in the prior art is solved.
In order to solve the above problem, an embodiment of the present application provides a data transmission method for a low-speed channel, including: sending a query signal to a preset slave signal end, and receiving a response signal of the slave signal end responding to the query signal within a first preset time length; judging whether the slave signal end has data to be transmitted according to the response signal, and judging whether the master signal end has data to be transmitted according to the response signal; sending a synchronous signal, and distributing a serial number of a data transmission time slot for the signal end to be sent with data; and the signal end performs data transmission in the allocated serial number data transmission time slot.
In one embodiment of the present application, the method further comprises: and after a second time length matched with the data transmission time slot, repeatedly sending the query signal and starting the next round of data transmission.
The answer signal includes: the identity of the slave signal end; the determining, according to the response signal, whether the main signal end has data to be transmitted further includes: and if the preset storage space of the main signal end contains cache data and the identity identifier in the response signal is the same as the target identity identifier carried in the cache data, determining that the main signal end has data to be sent.
The answer signal further includes: a data identifier for indicating whether the slave signal end has data to be transmitted; the determining, according to the response signal, whether the slave signal end has data to be transmitted further includes: and judging whether the slave signal end has data to be transmitted or not according to the data identification.
The sending synchronization signal allocates a sequence number of a data transmission timeslot to the signal end to which data is to be sent, and further includes: determining the number of the allocated data transmission time slots according to the number of the signal ends to be transmitted with data; distributing the serial number of the data transmission time slot corresponding to the identity of the signal end in the synchronous signal; and sending the synchronization signal to instruct the signal end to perform data transmission in the allocated serial number data transmission time slot.
The signal end performs data transmission in the allocated serial number data transmission time slot, specifically: and the signal terminal sends the data to be sent cached in a preset sliding window according to a sliding window protocol in the distributed serial number data transmission time slot and receives a response aiming at the data sent by the other signal terminal.
And the second duration matched with the data transmission time slot is greater than or equal to the product of the number of the distributed data transmission time slots and the length of the preset time slot.
The application also discloses a data transmission method for the low-speed channel, which comprises the following steps: receiving a query signal sent by a preset main signal end, sending a response signal responding to the query signal, and indicating the main signal end to allocate a corresponding data transmission time slot according to the response signal; and receiving a synchronous signal, and performing data transmission in the sequence number data transmission time slot distributed in the synchronous signal.
The data transmission is performed in the sequence number data transmission time slot allocated in the synchronization signal, specifically: and sending the data to be sent cached in a preset sliding window according to a sliding window protocol in the allocated serial number data transmission time slot, and receiving a response aiming at the data sent by the opposite signal terminal.
Correspondingly, the application also discloses a data transmission system for the low-speed channel, which comprises: the query module is used for sending a query signal to a preset slave signal end and receiving a response signal of the slave signal end responding to the query signal within a first preset time length; the data judgment module is used for judging whether the slave signal end has data to be sent according to the response signal and judging whether the master signal end has data to be sent according to the response signal; the time slot allocation module is used for sending a synchronous signal and allocating the serial number of a data transmission time slot for the signal end to be sent with data; and the first data transmission module is used for the signal end to perform data transmission in the allocated serial number data transmission time slot.
In another embodiment of the present application, the system further comprises: and the circulating module is used for repeatedly sending the query signal after the second time length matched with the data transmission time slot and starting the next round of data transmission.
The answer signal includes: the identity of the slave signal end; the determining, according to the response signal, whether the main signal end has data to be transmitted further includes: and if the preset storage space of the main signal end contains cache data and the identity identifier in the response signal is the same as the target identity identifier carried in the cache data, determining that the main signal end has data to be sent.
In a specific implementation, the response signal further includes: a data identifier for indicating whether the slave signal end has data to be transmitted; the determining, according to the response signal, whether the slave signal end has data to be transmitted further includes: and judging whether the slave signal end has data to be transmitted or not according to the data identification.
In one embodiment of the present application, the timeslot assignment module further includes: the time slot number determining submodule is used for determining the number of the distributed data transmission time slots according to the number of the signal ends to be sent with data; the time slot serial number distribution submodule is used for distributing the serial number of the data transmission time slot corresponding to the identity of the signal end in the synchronous signal; and the time slot allocation submodule is used for sending the synchronous signal to indicate the signal terminal to perform data transmission in the allocated serial number data transmission time slot.
The first data transmission module is further configured to: and sending the data to be sent cached in a preset sliding window according to a sliding window protocol in the allocated serial number data transmission time slot, and receiving a response aiming at the data sent by the opposite signal terminal.
The present application also discloses a data transmission system for a low-speed channel, comprising: the signal transceiver module is used for receiving a preset inquiry signal sent by the main signal end, sending a response signal responding to the inquiry signal and indicating the main signal end to allocate a corresponding data transmission time slot according to the response signal;
the signal receiving and transmitting module is also used for receiving a synchronous signal; and the second data transmission module is used for carrying out data transmission in the sequence number data transmission time slot distributed in the synchronous signal.
The second data transmission module is further configured to: and sending the data to be sent cached in a preset sliding window according to a sliding window protocol in the allocated serial number data transmission time slot, and receiving a response aiming at the data sent by the opposite signal terminal.
The method comprises the steps that a query signal is sent to a preset slave signal end through a master signal end, and the master signal end and the slave signal end with data to be sent are determined according to a response signal of the query signal; and then, only allocating the serial number of the data transmission time slot for the signal end to be sent data, so that the signal end performs data transmission in the allocated serial number data transmission time slot, and different signal ends have respective data transmission time slots, thereby effectively avoiding data loss caused by collision in the data transmission process in the prior art, effectively ensuring the stability of data transmission, and simultaneously, only allocating the data transmission time slot for the signal end to be sent data, ensuring the timely sending of data, reducing the waste of bandwidth and improving the utilization rate of a channel.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
FIG. 1 is a flow chart of one embodiment of a data transmission method of the present application;
FIG. 2 is a flow chart of another embodiment of a data transmission method of the present application;
FIG. 3 is a schematic diagram of a sliding window storage in an embodiment of the data transmission method of the present application;
FIG. 4 is a flow chart of yet another embodiment of the data transmission method of the present application;
FIG. 5 is a block diagram of one embodiment of the data transmission system of the present application;
FIG. 6 is a block diagram of another embodiment of the data transmission system of the present application;
fig. 7 is a block diagram of still another embodiment of the data transmission system of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In embodiments of the present application, a master signal end is a signal transmitting device that actively initiates communication, a slave signal end is a signal transmitting device that performs data sending operation according to triggering of the master signal end, and the signal transmitting device performs role operation of the master signal end or the slave signal end according to configuration of a user, where the master signal end and the slave signal end may be the same signal end (i.e., the same signal transmitting device) or different signal transmitting devices (i.e., different signal transmitting devices), which is not limited in this application. The opposite signal end is different from the local signal end, and may be a master signal end or a slave signal end in specific implementation.
The first embodiment is as follows:
the application discloses a data transmission method for a low-speed channel, which is applied to a mobile terminal, and as shown in fig. 1, the method includes:
in step 140, the signal end performs data transmission in the allocated serial number data transmission time slot.
In the above step 110, the signal transmitting device is preset with identity information and identity information of an opposite terminal device to be communicated in the network, where the identity information includes: whether the signal terminal is a master signal terminal or a slave signal terminal, the identity of the signal terminal and the identity of the signal terminal of the other party to be communicated. The method comprises the steps that when the signal transmitting equipment judges that the signal transmitting equipment is a main signal end per se according to preset identity information, a query frame is sent to opposite-end equipment to be communicated, then, first preset time duration is determined according to the number of the opposite-end equipment to be communicated and preset response time of each opposite-end equipment, and response signals of the signal transmitting end responding to the query signals are received within the first preset time duration. The first preset duration is greater than or equal to the sum of the response time of the opposite terminal equipment to be communicated.
In a specific implementation, the response signal includes the identity of the slave signal terminal. In the step 120, the determining whether the main signal end has data to be transmitted according to the response signal further includes: and if the preset storage space of the main signal end contains cache data and the identity identifier in the response signal is the same as the target identity identifier carried in the cache data, determining that the main signal end has data to be sent. For example, when the master signal end determines that there is cache data in a preset storage space, the master signal end matches a target identity carried in the cache data in an identity carried in a received response signal, and if the matching is successful, it indicates that a slave client receiving the data is online, it is determined that the master signal end has data to be sent; if the matching fails, it is indicated that the slave client receiving the data is not on the network and cannot successfully receive the data, and it is determined that the master signal end has no data to be sent. And determining whether to send data or not by combining the network state of the target client and the data caching condition of the main client, so that invalid data transmission can be avoided, and the data transmission efficiency is further improved.
For the slave signal end, it can be considered that all the slave signal ends which have sent the response signals have data to be sent, and the slave signal ends which have sent the response signals are allocated with data transmission time slots with specified sequence numbers.
In a preferred embodiment of the present application, the reply signal includes a data identifier for indicating whether the slave signal side has data to transmit; in the above step 120, the determining whether the slave signal end has data to be transmitted according to the response signal further includes: and judging whether the slave signal end has data to be transmitted or not according to the data identification. After the main signal end receives the response signal sent by the slave signal end, if the data identification in the response signal indicates that the slave signal end has data to send, the data transmission time slot with the appointed sequence number is distributed to the slave signal end; if the data identification in the response signal indicates that the slave signal terminal does not have data to be sent, the slave signal terminal is not allocated with a data transmission time slot, so that the data transmission time slot is fully utilized, and the data transmission efficiency is improved.
In another specific embodiment of the present application, in the step 130, the sending a synchronization signal, allocating a sequence number of a data transmission timeslot to the signal end to which data is to be sent, further includes: determining the number of the allocated data transmission time slots according to the number of the signal ends to be transmitted with data; distributing the serial number of the data transmission time slot corresponding to the identity of the signal end in the synchronous signal; and sending the synchronization signal to instruct the signal end to perform data transmission in the allocated serial number data transmission time slot. The synchronization signal carries the data transmission time slot sequence number corresponding to each signal end. Suppose there are five signal transmitting devices in the local area network, where the identity of the master signal end is 0, and the identity of the four slave signal ends are 1, 2, 3, and 4, respectively, where the master signal end with the identity of 0 is to send data, and the slave signal ends with the identities of 1, 3, and 4 are to send data, the master signal end needs to allocate data transmission time slots for the signal end 0, the signal end 1, the signal end 3, and the signal end 4 to send data, respectively, and the master signal end needs to allocate 4 data transmission time slots in total. Then, signal end identification bits corresponding to 4 data transmission time slots are set in the synchronization signal, and the serial number of the data transmission time slot is the offset of the signal end identification bits relative to the frame header. For example, the format of the synchronization signal is set as follows:
| frame header | Time slot 1 | Time slot 2 | Time slot 3 | Time slot 4 | Others |
| 0xA4 | 0 | 1 | 3 | 4 | -- |
Wherein 0xA4 is used to indicate that the data frame is a sync frame; 0. 1, 3 and 4 are the identification of the signal end to be transmitted with data. Assuming that 0 is the id of the master signal end, 1, 3, and 4 are the ids of the slave signal ends, respectively, and the data in the table above is used to indicate: the serial number of the data transmission time slot allocated to the master signal end is 1, the serial number of the data transmission time slot allocated to the slave signal end with the identity identifier of 1 is 2, the serial number of the data transmission time slot allocated to the slave signal end with the identity identifier of 3 is 3, and the serial number of the data transmission time slot allocated to the slave signal end with the identity identifier of 4 is 4. The above is merely an example of allocating a data transmission timeslot with a designated serial number to the signal end to which data is to be transmitted, and those skilled in the art may also design other specific schemes to allocate a data transmission timeslot with a designated serial number to the signal end from which data is to be transmitted, which is not limited in this application.
Then, in step 140, the master signal terminal transmits data in the 1 st data transmission slot, the slave signal terminal 1 transmits data in the 2 nd data transmission slot, the slave signal terminal 3 transmits data in the 3 rd data transmission slot, and the slave signal terminal 4 transmits data in the 4 th data transmission slot.
The embodiment of the application sends the query signal through the main signal terminal, and determines the main signal terminal and the slave signal terminal with data to be sent according to the response signal of the query signal; and then, only allocating the serial number of the data transmission time slot for the signal end to be sent data, so that the signal end performs data transmission in the allocated serial number data transmission time slot, and different signal ends have respective data transmission time slots, thereby effectively avoiding data loss caused by collision in the data transmission process in the prior art, effectively ensuring the stability of data transmission, and simultaneously, only allocating the data transmission time slot for the signal end to be sent data, ensuring the timely sending of data, reducing the waste of bandwidth and improving the utilization rate of a channel.
Example two:
in another specific embodiment of the present application, as shown in fig. 2, after step 130, the method further comprises:
and 150, after the main signal end is matched with the data transmission time slot for the second time length, repeatedly sending the query signal, and starting the next round of data transmission. After the main signal end sends the synchronous signal, the main signal end waits for a data transmission period with a second duration, and after the data transmission period is finished, the main signal end repeatedly sends the query signal to start the next round of data transmission. In each data transmission cycle, the clients to be sent data include a master client and a slave client, and data transmission is completed according to a data transmission timeslot designated by the master client, for example: sending data to be sent, receiving a response, and the like. In specific implementation, the second duration matched with the data transmission time slot is greater than or equal to the product of the number of the allocated data transmission time slots and the length of the preset time slot.
By setting the waiting time length matched with the data transmission time slot, the transmission time of the data to be transmitted can be ensured, and the waste of channel bandwidth caused by idle waiting can be avoided.
Example three:
in another specific embodiment of the present application, the step 110 further includes: the method comprises the steps of setting a threshold number of first preset size storage spaces for caching data, and setting a threshold number of second preset size storage spaces for storing data sending information in the threshold number of first preset size storage spaces. In specific implementation, the maximum byte number of one-time data transmission is determined based on the principle of maximizing the data sending efficiency of the signal end according to the factors of the transmitting frequency, the data processing capacity and the like of the signal end, the maximum byte number is taken as a preset size, and a storage space with the preset size of a threshold number is set at the signal end. The threshold number is determined comprehensively according to the amount of data to be sent at the signal end and the size of the storage space at the signal end, which is not limited in the present application.
The signal end performs data transmission in the allocated serial number data transmission time slot, specifically: and the signal terminal sends the data to be sent cached in a preset sliding window according to a sliding window protocol in the distributed serial number data transmission time slot and receives a response aiming at the data sent by the other signal terminal. In the embodiment of the application, the first preset size storage space with the threshold number is used as a space for storing data in the sliding window, and the second preset size storage space with the threshold number is used as a storage space in the sliding window state. When implemented specifically. Assuming that the threshold number is 10, the first predetermined size is 126 bytes, and the second predetermined size is 12 bytes, the data storage structure of the sliding window is shown in fig. 3, where 310 is a data storage space, 320 is a storage space in a sliding window state, and each sliding window state storage space 320 corresponds to one data storage space 310. The format of the data storage space is as follows:
| source ID | Object ID | Data sequence number | Data of |
| 1 byte | 1 byte | 6 bytes | 118 bytes |
The source ID is an identity of a signal end for sending data, the target ID is an identity of a signal end for receiving data, the data sequence number is used for representing a sequence number of a current data packet to be sent, and the data is to-be-sent data. In specific implementation, the signal end analyzes the data collected from the network card, deletes the data related to the network transmission protocol, and extracts the original data in the data packet.
The storage format of the sliding window state is as follows:
| protocol identification | State of use | Sending number | Number of timeouts | Retransmission flag | Read-write sign | Retention |
| 6 bytes | 1 byte | 1 byte | 1 byte | 1 byte | 1 byte | 1 byte |
Wherein, the protocol identification (Seq for ComSever) is used for indicating the protocol used by the communication service software transmission; the Use State (USED) is USED for indicating whether the space of the sliding window represented by the current address for storing data is USED or not; the transmission number (SEQ) represents a transmission number added by upper data transfer software when data is transmitted; the TIMEOUT times (TIMEOUT) are used for indicating the TIMEOUT times of data transmission in the sliding window represented by the current address; a retransmission flag (RESEND) is a data retransmission flag in a sliding window represented by a current address; the READ-write flag (READ) is used to indicate whether the data in the sliding window represented by the current address has been READ.
The sliding window protocol is a flow control method used by TCP. This protocol allows the sender to send multiple packets in succession before stopping and waiting for an acknowledgement. This protocol can speed up the transmission of data since the sender does not have to stop waiting for an acknowledgement every time a packet is sent. Automatic Repeat-reQuest (ARQ) is one of the error correction protocols at the data link layer in the OSI model. It achieves reliable information transfer on an unreliable service basis by using two mechanisms, acknowledgment and timeout. The sender will typically retransmit if it does not receive an acknowledgement frame within a period of time after transmission. ARQ may include stop-and-wait ARQ protocols, fallback ARQ and continuous ARQ protocols, error detection (error detection), Positive acknowledgement (Positive acknowledgement), Retransmission timeout (Retransmission acknowledgement) and Negative acknowledgement and Retransmission (Negative acknowledgement and Retransmission) mechanisms.
When the method is implemented specifically, when a space for storing data in a sliding window of a signal end is to be used for transmitting data, a read-write flag byte of a corresponding address in a sliding window state storage space corresponding to the space is set, when the current signal end judges that a data transmission time slot appointed for the current signal end arrives, the read-write flag byte in the sliding window state storage space is detected, if the read-write flag byte is not read, and the use state indicates that the current sliding window is not used, the use state of the current sliding window is set to be in use, and the data to be transmitted in the current sliding window is transmitted. Within the time range allowed by the data transmission time slot, the signal terminal can continue to transmit the data to be transmitted in other spaces for storing data in the sliding window without waiting for the currently transmitted data response. In the specific implementation of the method, the data is sent by combining a sliding window protocol with a continuous ARQ protocol, and the automatic retransmission of the data to be sent is realized by adopting a selective retransmission protocol so as to ensure the stability of data transmission. After the signal end for transmitting data transmits one packet of data to be transmitted, the signal end for transmitting data continuously transmits the next packet of data in the appointed data transmission time slot without waiting for the response of the signal end of the opposite side. If the response to a certain packet of data from the opposite signal end is not received within the set time, the data packet without the response is retransmitted. And after the data transmission is completed and the response is successfully received, clearing the state of the corresponding space in the sliding window. For use in caching the next packet of data.
The data is transmitted by combining the sliding window protocol with the continuous ARQ protocol, so that the full utilization of data transmission time slots is realized, the data transmission efficiency is improved, meanwhile, the data which is not normally transmitted can be automatically retransmitted, and the stability of data transmission is further ensured.
Example four:
in another embodiment of the present application, a data transmission method for a low-speed channel is disclosed, as shown in fig. 4, including:
After receiving the query signal sent by the main signal end, the slave signal end sends a response signal and responds to the query signal, wherein the response signal comprises the identity of the signal end. Preferably, the response signal further includes a data identifier for indicating whether the slave signal end has large transmission data.
In specific implementation, the synchronization signal carries the serial number of the data transmission time slot corresponding to the signal end identity identifier.
In the embodiment, data transmission is performed in the data transmission time slot designated by the main signal end, so that data loss caused by channel collision can be effectively avoided, and the stability of data transmission is ensured.
In specific implementation, the step of setting the threshold number of first preset size storage spaces is used for caching data, and the step of setting the threshold number of second preset size storage spaces is used for storing data sending information in the threshold number of first preset size storage spaces. The data transmission is performed in the sequence number data transmission time slot allocated in the synchronization signal, specifically: and sending the data to be sent cached in a preset sliding window according to a sliding window protocol in the allocated serial number data transmission time slot, and receiving a response aiming at the data sent by the opposite signal terminal. In this embodiment, a specific implementation manner of presetting a storage space and performing data transmission by using a sliding window protocol is referred to as embodiment three, and details are not described here.
The continuous data transmission is realized by using the sliding window protocol, so that the full utilization of data transmission time slots is realized, the data transmission efficiency is improved, meanwhile, the automatic retransmission can be realized for the data which is not normally transmitted, and the stability of data transmission is further ensured.
Example five:
the data transmission method for the low-speed channel of the self-application is described in detail below in connection with a specific use scenario in military war.
According to the practical application condition, the signal end is a short-wave radio station, the short-wave radio station is used on an operation command vehicle, a continuous command vehicle and a fixed command post, and one-to-four networking is used at most. In specific implementation, the short-wave radio station is preferably realized by adopting an FPGA processing chip, and in the process of executing data transmission, the FPGA processor dynamically allocates time slots according to the role of the short-wave radio station. In actual use, the situation that the camp command vehicle sends data to the continuous command vehicle and the fixed command post or the continuous command vehicle and the fixed command post send data to the camp command vehicle only occurs. Therefore, the camp command vehicle is set as a master station (namely, a master signal end), the continuous command vehicle and the fixed command post are set as slave stations (namely, slave signal ends), the specific networking master-slave configuration relationship configures each signal end in a configuration file or manual setting mode, and the configuration information comprises: identity, role, other roles within the network and identity. In the following description of the embodiments, the example of including five signal terminals in the network is described. The five signal ends are respectively: the system comprises a camp command vehicle, a continuous command vehicle 1, a continuous command vehicle 2, a continuous command vehicle 3 and a fixed command post, wherein the camp command vehicle is a main signal end, and the identity of the camp command vehicle is 0; the continuous command vehicle 1 is a slave signal end, and the identity of the continuous command vehicle is 1; the continuous command vehicle 2 is a slave signal end, and the identity of the continuous command vehicle is 2; the continuous command vehicle 3 is a slave signal end, and the identity of the continuous command vehicle is 3; the fixed command post is the slave signal end, and the identity of the fixed command post is 4.
Firstly, 10 data storage spaces for storing data to be sent of 126 bytes and 10 state storage spaces for storing the state of the data storage spaces of 12 bytes are pre-allocated to the operation command vehicle, the command vehicle 1, the command vehicle 2, the command vehicle 3 and the fixed command post respectively.
Then, the operation command vehicle determines that the operation command vehicle is a master signal terminal according to the stored configuration information, and sends query signals 0xA3 to other four slave signal terminals in the network, including: the command vehicle 1, the command vehicle 2, the command vehicle 3 and the fixed command post) and determines the time for waiting for at least 4T according to the expected time length T of the response signal returned by each slave signal end, so as to ensure that the four slave signal ends wait for a long enough time to receive the responses fed back by the four slave signal ends when all the four slave signal ends are on line.
And after receiving the inquiry signal sent by the main signal end, the slave signal end sends a response signal responding to the inquiry signal, and the response signal is used for indicating the main signal end to allocate a corresponding data transmission time slot according to the response signal. The answer signal includes: the identity of the slave signal end and the data identity of whether data are to be transmitted or not.
After receiving the response signal fed back by the slave signal end of the on-line network, the master signal end judges whether the slave signal end needs to send data or not according to the data identification in the response signal, and the slave signal end is a slave signal end decibel data transmission time slot of the data to be sent. And determining whether to allocate a data transmission time slot for the main signal end according to whether the main signal end buffers data to be transmitted and whether a target signal end of the data to be transmitted is on the network. In this embodiment, four slave signal terminals all transmit a response signal of an inquiry signal, and two of the slave signal terminals (i.e., command car 2 and command car 3) have data to be transmitted, and the master signal terminal (command car for camping) has no data to be transmitted, so that the master signal terminal (command car for camping) allocates 2 data transmission time slots: the 1 st data transmission time slot is allocated to the continuous command vehicle 2, and the 2 nd data transmission time slot is allocated to the continuous command vehicle 3.
The command bus allocates the designated data transmission time slot for the slave signal end (namely the command bus 2 and the command bus 3) to be transmitted by sending the synchronous signal. The synchronous signal that the command car of camping sent does: 0xA4,0x02,0x03, wherein 0xA4 is sync frame id, 0x02 is used to indicate that the 1 st data transmission slot is allocated to the slave signal side with id 2 (i.e. car 2 connected), and 0x03 is used to indicate that the 2 nd data transmission slot is allocated to the slave signal side with id 3 (i.e. car 3 connected).
After receiving the synchronization signal, the continuous command vehicle 2 sends data to be sent in the data storage space in the 1 st data transmission time slot, and waits for a response signal in the time slot; and after receiving the synchronous signal, the continuous command vehicle 3 sends the data to be sent in the data storage space in the 2 nd data transmission time slot and waits for a response signal in the time slot.
After the camp command vehicle sends the synchronization signal, the camp command vehicle waits for the duration of 2 data transmission time slots for waiting for the continuous command vehicle 2 and the continuous command vehicle 3 to send data. If the target ID of the data to be sent in the continuous command vehicle 2 and the continuous command vehicle 3 is 0, that is, the identity of the camp command vehicle, the camp command vehicle receives the data sent by the continuous command vehicle 2 in the 1 st data transmission time slot after sending the synchronization signal, and sends the response data to the continuous command vehicle 2 in the 1 st data transmission time slot; and receiving the data sent by the continuous command vehicle 3 in the 2 nd data transmission time slot, and sending response data to the continuous command vehicle 3 in the 2 nd data transmission time slot. After waiting for 2 data transmission time slots, the camp command vehicle sends query signals to each slave signal end in the network again according to the configuration information of the camp command vehicle, and starts the next data transmission.
Example six:
accordingly, a data transmission system for a low-speed channel, as shown in fig. 5, includes:
the query module 510 is configured to send a query signal to a preset slave signal end, and receive a response signal of the slave signal end responding to the query signal within a first preset time period;
a data determining module 520, configured to determine whether the slave signal end has data to be sent according to the response signal, and determine whether the master signal end has data to be sent according to the response signal;
a time slot allocating module 530, configured to send a synchronization signal, and allocate a serial number of a data transmission time slot to the signal end to which data is to be sent;
a first data transmission module 540, configured to perform data transmission in the allocated serial number data transmission timeslot by the signal end.
The synchronization signal carries the serial number of the data transmission time slot corresponding to the identity of each signal end.
The embodiment of the application sends the query signal through the main signal terminal, and determines the main signal terminal and the slave signal terminal with data to be sent according to the response signal of the query signal; and then, only allocating the serial number of the data transmission time slot for the signal end to be sent data, so that the signal end performs data transmission in the allocated serial number data transmission time slot, and different signal ends have respective data transmission time slots, thereby effectively avoiding data loss caused by collision in the data transmission process in the prior art, effectively ensuring the stability of data transmission, and simultaneously, only allocating the data transmission time slot for the signal end to be sent data, ensuring the timely sending of data, reducing the waste of bandwidth and improving the utilization rate of a channel.
In a specific implementation, the response signal includes: the identity of the slave signal end; the determining, according to the response signal, whether the main signal end has data to be transmitted further includes: and if the preset storage space of the main signal end contains cache data and the identity identifier in the response signal is the same as the target identity identifier carried in the cache data, determining that the main signal end has data to be sent. And determining whether to send data or not by combining the network state of the target client and the data caching condition of the main client, so that invalid data transmission can be avoided, and the data transmission efficiency is further improved.
In another embodiment of the present application, the reply signal further includes: a data identifier for indicating whether the slave signal end has data to be transmitted; the determining, according to the response signal, whether the slave signal end has data to be transmitted further includes: and judging whether the slave signal end has data to be transmitted or not according to the data identification.
In another specific embodiment of the present application, the timeslot allocating module 530 further includes:
the time slot number determining submodule is used for determining the number of the distributed data transmission time slots according to the number of the signal ends to be sent with data;
the time slot serial number distribution submodule is used for distributing the serial number of the data transmission time slot corresponding to the identity of the signal end in the synchronous signal;
and the time slot allocation submodule is used for sending the synchronous signal to indicate the signal terminal to perform data transmission in the allocated serial number data transmission time slot.
In specific implementation, the first data transmission module 540 is further configured to: and sending the data to be sent cached in a preset sliding window according to a sliding window protocol in the allocated serial number data transmission time slot, and receiving a response aiming at the data sent by the opposite signal terminal. For a specific implementation of data transmission, refer to the method embodiment section, which is not described herein again. The continuous data transmission is realized by using the sliding window protocol, so that the full utilization of data transmission time slots is realized, the data transmission efficiency is improved, meanwhile, the automatic retransmission can be realized for the data which is not normally transmitted, and the stability of data transmission is further ensured.
In another specific embodiment of the present application, based on embodiment five, as shown in fig. 6, the system further includes:
and a cycle module 550, configured to repeatedly send the query signal after the second duration matching the data transmission time slot, and start a next round of data transmission.
In specific implementation, the second duration matched with the data transmission time slot is greater than or equal to the product of the number of the allocated data transmission time slots and the length of the preset time slot.
Example seven:
in another embodiment of the present application, a data transmission system for low-speed channel is disclosed, as shown in fig. 7, the system includes:
a signal transceiver module 710, configured to receive a query signal sent by a preset main signal end, send a response signal responding to the query signal, and instruct the main signal end to allocate a corresponding data transmission timeslot according to the response signal;
the signal transceiver module 710 is further configured to receive a synchronization signal;
and a second data transmission module 720, configured to perform data transmission in the sequence number data transmission timeslot allocated in the synchronization signal.
In specific implementation, the second data transmission module is further configured to:
and sending the data to be sent cached in a preset sliding window according to a sliding window protocol in the allocated serial number data transmission time slot, and receiving a response aiming at the data sent by the opposite signal terminal.
In the embodiment, data transmission is performed in the data transmission time slot designated by the main signal end, so that data loss caused by channel collision can be effectively avoided, and the stability of data transmission is ensured.
The embodiments in the present specification are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the device embodiment, since it is basically similar to the method embodiment, the description is simple, and for the relevant points, refer to the partial description of the method embodiment.
The present application has been described in detail with reference to the accompanying drawings, and specific examples are used herein to explain the principles and implementations of the present application, where the descriptions of the foregoing examples are only used to help understand the methods and core ideas of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Claims (6)
1. A data transmission method for a low-speed channel, comprising:
sending a query signal to a preset slave signal end, and receiving a response signal of the slave signal end responding to the query signal within a first preset time length, wherein the first preset time length is greater than or equal to the sum of response time of opposite terminal equipment to be communicated;
judging whether the slave signal end has data to be sent according to the response signal, and judging whether the master signal end has data to be sent according to the response signal;
sending a synchronous signal, and distributing a serial number of a data transmission time slot for the signal end to be sent with data;
the signal end performs data transmission in the allocated serial number data transmission time slot;
after a second time length matched with the data transmission time slot, repeatedly sending a query signal, and starting the next round of data transmission, wherein the second time length is greater than or equal to the product of the number of the distributed data transmission time slots and the length of a preset time slot;
wherein the reply signal comprises: the identity of the slave signal end; cache data exist in a preset storage space of the main signal end;
the determining whether the main signal end has data to be transmitted according to the response signal includes: the main signal end matches the target identity carried in the cache data in the identity carried by the received response signal, and if the matching is successful, the main signal end determines that the main signal end has data to be sent, which indicates that the slave signal end receiving the cache data is on-line; if the matching fails, the slave signal terminal receiving the cache data is not on the network and cannot successfully receive the data, and the master signal terminal is determined to have no data to be sent;
wherein, sending a synchronization signal, and allocating a sequence number of a data transmission time slot to the signal end to which data is to be sent, comprises:
determining the number of the allocated data transmission time slots according to the number of the signal ends to be transmitted with data; distributing the serial number of the data transmission time slot corresponding to the identity of the signal end in the synchronous signal; sending the synchronization signal to indicate the signal ends to perform data transmission in the allocated serial number data transmission time slots, wherein the synchronization signal carries the serial numbers of the data transmission time slots corresponding to the signal ends;
the master signal terminal is a signal transmitting device which actively initiates communication, and the slave signal terminal is a signal transmitting device which executes data transmitting operation according to the triggering of the master signal terminal.
2. The method of claim 1, wherein the reply signal further comprises: a data identifier for indicating whether the slave signal end has data to be transmitted;
the determining, according to the response signal, whether the slave signal end has data to be transmitted further includes: and judging whether the slave signal end has data to be transmitted or not according to the data identification.
3. The method of claim 1, wherein the signal side performs data transmission in the allocated serial number data transmission time slot, specifically:
and the signal terminal sends the data to be sent cached in a preset sliding window according to a sliding window protocol in the distributed serial number data transmission time slot and receives a response aiming at the data sent by the other signal terminal.
4. A data transmission system for a low-speed channel, comprising:
the system comprises a query module, a receiving module and a communication module, wherein the query module is used for sending a query signal to a preset slave signal end and receiving a response signal of the slave signal end responding to the query signal within a first preset time length, and the first preset time length is greater than or equal to the sum of the response time of opposite-end equipment to be communicated;
the data judgment module is used for judging whether the slave signal end has data to be sent according to the response signal and judging whether the master signal end has data to be sent according to the response signal;
the time slot allocation module is used for sending a synchronous signal and allocating the serial number of a data transmission time slot for the signal end to be sent with data;
the first data transmission module is used for the signal end to perform data transmission in the allocated serial number data transmission time slot;
the cycle module is used for repeatedly sending the query signal after a second time length matched with the data transmission time slot and starting the next round of data transmission, wherein the second time length is greater than or equal to the product of the number of the distributed data transmission time slots and the length of the preset time slot;
the answer signal includes: the identity of the slave signal end;
the determining whether the main signal end has data to be transmitted according to the response signal further includes: if cache data exist in a preset storage space of the main signal end and the identity identifier in the response signal is the same as the target identity identifier carried in the cache data, determining that the main signal end has data to be sent;
the timeslot assignment module further comprises:
the time slot number determining submodule is used for determining the number of the distributed data transmission time slots according to the number of the signal ends to be sent with data;
the time slot serial number distribution submodule is used for distributing the serial number of the data transmission time slot corresponding to the identity of the signal end in the synchronous signal;
the time slot distribution submodule is used for sending the synchronous signal to indicate the signal terminal to carry out data transmission in the distributed serial number data transmission time slot;
the master signal terminal is a signal transmitting device which actively initiates communication, and the slave signal terminal is a signal transmitting device which executes data transmitting operation according to the triggering of the master signal terminal.
5. The system of claim 4, wherein the reply signal further comprises: a data identifier for indicating whether the slave signal end has data to be transmitted;
the determining, according to the response signal, whether the slave signal end has data to be transmitted further includes: and judging whether the slave signal end has data to be transmitted or not according to the data identification.
6. The system of claim 4, wherein the first data transmission module is further to:
and sending the data to be sent cached in a preset sliding window according to a sliding window protocol in the allocated serial number data transmission time slot, and receiving a response aiming at the data sent by the opposite signal terminal.
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