TWI734282B - Method for data transmission and communication system thereof - Google Patents

Abstract

A method for data transmission and a communication system thereof are provided. The communication system includes a server and one or more terminal devices. The method is operated in the terminal device. If the terminal device does not receive any acknowledgment packet within a preset period of time after sending packets to the server, the packets are reserved in a memory of the device. After that, when reaching a predetermined resending time, a controller of the terminal device checks if any packet is reserved in the memory. If the memory reserves the packet to be resent, the packet can be resent with a data rate in the predetermined resending time.

Description

Data transmission method and communication system

The invention relates to a data transmission method, in particular to a data transmission method and its communication system used in Internet of Things communication.

In the application of the Internet of Things (IoT), one of the most important features is the communication system that adopts the design principle of power saving. The terminal device of the Internet of Things is generally an electronic device that uses an embedded operating system, such as various sensors. , Network devices, home appliances, etc.

A communication system for the Internet of Things is realized, in which all terminal devices are connected through the network, especially using a communication protocol with low energy consumption characteristics, such as long-distance low-power wireless network technology (LoRa), BLE (Bluetooth Low Energy) , Zigbee, etc.

However, when the wireless communication technology applied in the Internet of Things mainly considers the demand for low energy consumption, the disadvantage is that when a packet is lost, the reason for the loss of the packet may be caused by the failure of the gateway connected to the device (Gateway is Out of service), Device is out of gateway coverage (Device is out of gateway coverage), packet collision (Signal collision) and noise interference (Noise interference), etc., when the conventional communication technology lacks data retransmission or repeated confirmation The mechanism of whether the packet arrives or not makes this kind of communication technology unable to undertake the task of transmitting important data.

The manual discloses a data transmission method and communication system for the Internet of Things, one of the purposes is to solve the problem of incomplete data caused by the loss of packets due to the wireless communication technology commonly used in the Internet of Things.

According to the embodiment, the communication system includes a server running in an Internet of Things and one or more terminal devices. Each terminal device includes a controller, and a communication unit, a memory unit, and a working unit electrically connected to the controller.

When the communication system is running, the information generated by the terminal device will be converted into a packet through the communication unit for transmission to the server. In the data transmission method described, if the confirmation packet returned by the server is not obtained after the packet is transmitted, The control circuit in the terminal device stores this packet in the memory. When a predetermined retransmission time is reached, the control circuit checks whether there is any packet stored in the memory waiting to be retransmitted. If there is, within the predetermined retransmission time, a data transmission rate and the maximum data of the packet will be transmitted at one time Resend the packets stored in the memory waiting to be re-sent.

Further, when resending a packet stored in the memory waiting to be resent, the system sets the upper limit of the number of resends. If the upper limit of the number of resends is reached and the resending still cannot be completed, the resent packet will be saved again in the In memory.

Preferably, the terminal device is provided with a predetermined resend time, which is a time set by the control circuit to resend the packet stored in the memory according to the data transmission status of the device. The data transmission rate and the maximum data volume are set according to the current signal-to-noise ratio (SNR) and received signal strength indicator (RSSI) of the terminal device.

Further, when the data transmission rate is determined, or the maximum data amount is added, the wireless modulation parameters for the operation of the communication unit in the terminal device are determined.

In order to further understand the features and technical content of the present invention, please refer to the following detailed description and drawings about the present invention. However, the provided drawings are only for reference and description, and are not used to limit the present invention.

The following are specific specific examples to illustrate the implementation of the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be based on different viewpoints and applications, and various modifications and changes can be made without departing from the concept of the present invention. In addition, the drawings of the present invention are merely schematic illustrations, and are not drawn according to actual dimensions, and are stated in advance. The following embodiments will further describe the related technical content of the present invention in detail, but the disclosed content is not intended to limit the protection scope of the present invention.

It should be understood that although terms such as "first", "second", and "third" may be used herein to describe various elements or signals, these elements or signals should not be limited by these terms. These terms are mainly used to distinguish one element from another, or one signal from another signal. In addition, the term "or" used in this document may include any one or a combination of more of the associated listed items depending on the actual situation.

Wireless communication technologies used in the Internet of Things (IoT) are common, such as long-distance low-power wireless network technology (LoRa), BLE (Bluetooth Low Energy), Zigbee, etc. The communication protocol of this type of communication technology takes things into consideration. Because of the characteristics of network operation, it has a low energy consumption design. In communication technology, in order to achieve low energy consumption, one of the methods is to use power management technology to allow terminal devices (such as sensors, signal transmitters, audio receivers, etc.) Etc.) It goes to sleep when it is not operating until a wake-up condition is met; other solutions only provide bandwidth for transmitting small data packets and avoid full-time operation; or streamline the communication protocol, such as when packets are sent out At this time, it does not confirm whether the other party has received it, or saves the mechanism of re-sending the packet, so it is more suitable for applications that transmit smaller data, or applications of the Internet of Things that only transmit data packets with low security.

However, the disadvantage of this type of communication technology is the problem of incomplete data caused by packet loss. The possible reasons for packet loss are the failure of the gateway to which the device is connected (Gateway is out of service), and the device leaving the coverage of the gateway signal. (Device is out of gateway coverage), packet collision (Signal collision) and noise interference (Noise interference), etc., when the conventional communication technology lacks data retransmission or repeatedly confirm whether the packet arrives or not, it also makes this type of communication Technology cannot take on the task of transmitting important data.

The manual discloses a data transmission method and communication system, which can be a communication technology applied to the Internet of Things, but it still does not rule out the communication needs between users’ general devices. The data transmission method disclosed therein mainly aims to solve the common problems of the Internet of Things. The communication protocol will cause the problem of packet loss that cannot be solved due to the requirement of low energy consumption. The main technical feature to solve the problem is to save the data packet that cannot be confirmed whether it has been delivered in the memory of the device, and wait for a scheduled retransmission. Time to resend again. It is mentioned here that the predetermined retransmission time is a time set by a controller in the terminal device to retransmit the packet stored in the memory according to the data transmission status of the communication unit.

Figure 1 shows a schematic diagram of the system architecture of the communication system.

The communication system shown in the figure covers a local area network with a server 15, such as a central server in the Internet of Things, which is used to contact terminal devices 10 deployed everywhere. One or more terminal devices 10 can pass through the gateway The server 12 is connected to the server 15. Each terminal device 10 in the communication system is, for example, a sensor, a network device or others in the Internet of Things. The main control circuit of the terminal device 10 is shown in the figure as the controller 101, which is used to control the entire terminal device 10. The operation of the terminal device, as well as the communication and control of other circuit elements; is provided with a communication unit 102, which is electrically connected to the controller 101, which is a communication circuit supporting a specific wireless communication protocol. The terminal device 10 is connected to the server 15 through the communication unit 102, and The information generated by the terminal device 10 is transmitted; there is a memory unit 103, which is used for the operation of the terminal device 10, especially as a reserved memory for storing packets; and a working unit 104, which is the terminal device 10 in the Internet of Things The operating functions in the system can be sensor components, signal transmitters, audio receivers, etc. The information generated by the operation of the working unit 104, such as sensing signals, can be processed by the controller 101 and converted into the communication unit 102. The packet of a specific communication protocol is sent to the server 15.

Under this communication system architecture, when the connection between the terminal device 10 and the gateway 12, or the connection between the gateway 12 and the server 15, occurs, for example, the signal is interrupted, or the connection between the gateway 12 The wireless communication signal cannot cover the terminal device 10, or the collision of packets to and from the terminal device, or other interference, causes the terminal device 10 to transmit the packet, and the packet cannot reach the server 15 smoothly, or the acknowledgement packet (ACK packet) cannot be received. It is impossible to confirm whether the server 15 has received the packet. In this case, the data transmission method implemented in the terminal device 10 of the communication system will propose a solution.

Figure 2 shows a schematic diagram of the operation sequence of the data transmission method. It shows a terminal device 20 that communicates with a server 25. Other network devices (such as gateways) can be used in the middle, and the data transmission method is not restricted. .

The terminal device 20 transmits a packet to the server 25, such as an uplink packet 201 (uplink packet) as shown in the figure, and should receive an acknowledgment packet (ACK) 203 corresponding to the packet within a time, and then transmits the next uplink packet 205. The confirmation packet 207 should be received within the time, but when the confirmation packet 207 is not received after the timeout, the upstream packet 205 will be stored in the memory of the terminal device 20.

Afterwards, when a predetermined retransmission time 22 is reached, the control circuit in the terminal device 20 will check whether there is any packet stored in the memory unit waiting to be retransmitted. Once the packet to be retransmitted is stored, it is scheduled here During the retransmission time 22, a data rate is determined according to the current communication quality of the terminal device 20 and the network state, or a maximum size of data/packet is also determined at one time. In the scheduled resend time 22, the packets stored in the memory unit waiting to be resent are resent at the currently determined data transmission rate and/or the maximum amount of data, forming the uplink packets 209, 213 resent within this time in the diagram, and Similarly, it is still possible to wait for the corresponding confirmation packets 211, 215, etc.

For the flow of the related method embodiment, please refer to the flow chart (A) of the embodiment of the data transmission method shown in FIG. 3.

In this process (A), at the beginning, the terminal device generates a packet and then transmits an uplink packet to the server (step S301), and waits for an acknowledgement packet (ACK) (step S303), where the control circuit determines whether it has timed out before Received the confirmation packet? (Step S305). If the corresponding confirmation packet has been received (Yes), the terminal device continues to work (step S307), and the flow returns to step S301, where the next packet can be transmitted and the steps of waiting for the confirmation packet can be continued. When there is no packet to be transmitted, the terminal device can continue its original work or enter a power-saving state such as sleep.

When it is judged that the confirmation packet has not been received (No), the control circuit continues to judge whether the timeout time set by the system according to the actual demand has been exceeded? (Step S309), if the time has not expired (No), continue to wait for the confirmation packet (Step S303) and related steps.

If it has timed out and the confirmation packet has not been received (Yes), the control circuit of the terminal device saves the current packet in the memory (step S311). When the packet is saved in the queue memory, it can also execute a Compression step.

When it is not confirmed whether the transmitted packet is stored in the memory, the process of the data transmission continues with the process (B) of the embodiment shown in FIG. 4.

In this process (B), the control circuit of the terminal device operates to wait for the predetermined retransmission time (step S401), and determines whether the predetermined retransmission time is reached? (Step S403), if the predetermined retransmission time set by the system has not been reached (No), the process continues to step S401.

If the predetermined retransmission time has elapsed (Yes), the control circuit of the terminal device will determine a data transfer rate according to the current communication quality or the operating state of the device (step S405), and then send the data stored in the memory to the waiting list at this data transfer rate. To resend the packet, first take out the packet, decompress it if necessary (step S407), and then resend the packet (step S409). When the resending packet is completed, the process also returns to the process (A) described in Figure 3.

Fig. 5 schematically shows an example of a packet staying in the memory. It shows a reserved memory 50 in which the saved packets are stored in different memory blocks. In this example, the first packet 501 and the second packet are marked. Packet 502 and the third packet 503. When the predetermined retransmission time is reached, the control circuit of the terminal device obtains the packet to be retransmitted from the reserved memory 50. If the retransmission has not been completed, it may be stored in this memory again.

FIG. 6 shows a flowchart of an embodiment of a data transmission method running in the control circuit of the terminal device.

When the control circuit of the terminal device judges that the time reaches the predetermined resend time (step S601), it actively checks the memory (such as the reserved memory) (step S603) to determine whether there is a saved packet? (Step S605)

If there is no saved packet to be resent (No), the process returns to the work of the terminal device (step S607); on the contrary, if it is checked that the packet to be resent is saved (Yes), the control circuit will determine the data transfer rate and Maximum data amount (step S609). In this step, the factors that determine the data transmission rate or the maximum amount of data transmitted at one time include the current signal-to-noise ratio (SNR) of the terminal device and the received signal strength indicator (RSSI), which will affect the current communication quality. In an embodiment, when the communication quality (data transmission rate, or plus the maximum amount of data) is judged to be good or bad based on the signal-to-noise ratio and/or received signal strength indicator, it can be determined that the communication unit in the terminal device operates The wireless modulation parameters are adapted to the current data transmission rate or maximum data volume to provide improved communication quality. In addition, the control circuit of the terminal device may save the historical record of the past transmission data. The historical record may include the transmission record of the terminal device at any time (such as communication quality), which is also a reference for judging the current data transmission rate or/and The basis for the maximum amount of data can also be used to determine the scheduled resend time.

When the conditions for retransmitting the packet such as the data transfer rate and the maximum amount of data are determined, the control circuit fetches the packet from the memory (step S611), decompresses it if necessary, and starts the nth retransmission (n=1 , 2, …m) (step S613). The system can determine the upper limit of the number of retransmissions (m), starting from the first transmission (n=1), and after retransmission, judge whether the confirmation packet is received? (Step S615), if the confirmation packet is successfully received (Yes), the flow returns to step S603 to continue to check the next packet to be resent and other steps.

On the contrary, if the confirmation packet has not been received (No), it is judged whether the upper limit of the number of retransmissions (m) has been reached? (Step S617). If the upper limit of the number of retransmissions has not been reached (No), the flow continues to step S619, the number of retransmissions (n) is increased by 1 (n+1), and the step S613 is continued to start the next retransmission (such as the second time... etc.), If the confirmation packet has not been received, the number of retransmissions (n) is accumulated until n=m (the upper limit of the number of times) (Yes), and step S621 is executed, which means that the retransmission cannot be completed after reaching the upper limit of the number of times (m). The re-sent packet this time is stored in the memory, and the flow returns to step S603.

To sum up, according to the description of the above embodiments, the proposed data transmission method can be applied to a communication system of the Internet of Things that has power saving, a small amount of data, and a communication protocol that does not actively retransmit packets. In the transmission method, the saved packet to be resent is retransmitted at the preset retransmission time set by the system or dynamically adjusted, so as to solve the problem caused by the lack of solutions for this type of system that cannot confirm whether the packet is delivered or not.

The content disclosed above is only the preferred and feasible embodiments of the present invention, and does not limit the scope of the patent application of the present invention. Therefore, all equivalent technical changes made using the description and schematic content of the present invention are included in the application of the present invention. Within the scope of the patent.

Terminal device 10 Controller 101 Communication unit 102 Memory unit 103 Work unit 104 Gateway 12 Server 15 Terminal device 20 Server 25 Upstream packets 201, 205, 209, 213 Confirm packet 203, 207, 211, 215 Scheduled resend time 22 Queue memory 50 The first packet 501 The second packet 502 The third packet 503 Steps S301～S311 IoT data transmission process Steps S401～S409 IoT data transmission process Steps S601～S621 IoT data transmission process

Figure 1 shows a schematic diagram of the system architecture of the communication system;

Figure 2 shows a schematic diagram of the operation sequence of the data transmission method;

Figure 3 shows one of the flowcharts of the embodiment of the data transmission method;

Figure 4 shows the second flow chart of the embodiment of the data transmission method;

Figure 5 schematically shows an example diagram of a packet remaining in the memory;

Fig. 6 shows a flowchart of an embodiment of a method for implementing data transmission.

Terminal device 20 Server 25 Upstream packets 201, 205, 209, 213 Confirm packet 203, 207, 211, 215 Scheduled resend time 22

Claims (10)

A data transmission method operates in a terminal device, the terminal device is provided with a memory, and includes: When a predetermined resend time is reached, check whether there are any packets stored in the memory waiting to be resent; and Within the predetermined retransmission time, retransmit the packets stored in the memory waiting to be retransmitted at a data transmission rate. The data transmission method according to claim 1, wherein when resending a packet stored in the memory waiting to be resent, an upper limit of the number of resends is set. If the upper limit of the number of resends is reached, the resending cannot be completed, that is, resend Save the re-sent packet this time in the memory. The data transmission method according to claim 1, wherein the predetermined retransmission time is a time set by a controller in the terminal device to retransmit the packet stored in the memory according to the data transmission status of a communication unit. The data transmission method according to claim 1, wherein when checking whether there is any packet stored in the memory to be resent, the data transmission is determined according to the current signal-to-noise ratio of the terminal device and the received signal strength indicator Rate. The data transmission method according to claim 4, wherein when checking whether there is any packet stored in the memory to be resent, a maximum data amount of the packet to be transmitted at a time is determined. The data transmission method according to claim 4 or 5, wherein when the data transmission rate is determined, or the maximum data amount is added, the wireless modulation parameter of a communication unit in the terminal device is determined. A communication system including: A server running in an Internet of Things; One or more terminal devices in the Internet of Things, each terminal device includes a controller, and a communication unit, a memory unit, and a working unit electrically connected to the controller, wherein the communication unit is connected to the server, And transmit the packet formed by the information generated by the work unit; Wherein, a data transmission method running on the controller includes: When a predetermined retransmission time is reached, check whether there is any packet in the memory unit that is saved and waiting to be retransmitted; and Within the predetermined retransmission time, the packets stored in the memory unit waiting to be retransmitted are retransmitted at a data transmission rate and a maximum data amount of the transmitted packet at a time. The communication system according to claim 7, wherein when resending a packet stored in the memory unit waiting to be resent, an upper limit of the number of resends is set, and if the upper limit of the number of resends is reached, the resend cannot be completed, that is, the packet is sent again The re-sent packet this time is stored in the memory unit. The communication system according to claim 8, wherein the predetermined retransmission time is a time for retransmitting the packet stored in the memory unit as set by the controller according to the data transmission status of the communication unit. The communication system according to any one of Claims 7 to 9, wherein when checking whether there is any packet stored in the memory unit to be resent, it is based on the current signal-to-noise ratio and received signal strength of the terminal device Instruct to determine the data transfer rate and the maximum amount of data.

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