CN112261731B - LoRa gateway downlink frame scheduling method based on dynamic priority - Google Patents
LoRa gateway downlink frame scheduling method based on dynamic priority Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/56—Allocation or scheduling criteria for wireless resources based on priority criteria
- H04W72/566—Allocation or scheduling criteria for wireless resources based on priority criteria of the information or information source or recipient
- H04W72/569—Allocation or scheduling criteria for wireless resources based on priority criteria of the information or information source or recipient of the traffic information
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/20—Control channels or signalling for resource management
- H04W72/23—Control channels or signalling for resource management in the downlink direction of a wireless link, i.e. towards a terminal
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Abstract
The invention relates to a dynamic priority-based LoRa gateway downlink frame scheduling method, and belongs to the field of coal mine safety monitoring and control. The method comprises a server, an LoRa gateway and a node, wherein the gateway comprises n independent radio frequency transmitting channels, each channel has the same hardware structure and performance, and n radio frequency signals can be transmitted simultaneously. The gateway uniformly schedules all transmitting channels, counts the success rate of downlink frame transmission of each activated node within a certain time, and dynamically divides the occupation priority of the transmitting channels according to the power; and selecting the downlink frame for the optimal scheduling target to transmit by using the maximum transmission channel utilization rate and the weighted sum of the highest priority. The invention can improve the utilization rate of the gateway downlink communication channel when the network is congested, and simultaneously ensures the success rate of downlink frames of different nodes by dynamically adjusting the priority of the downlink frames of the nodes, thereby avoiding that individual nodes cannot receive the downlink frames for a long time when the network is busy.
Description
Technical Field
The invention belongs to a coal mine safety monitoring domain, and relates to a remote LoRa gateway downlink frame scheduling method based on dynamic priority.
Background
At present, a coal mine safety monitoring system basically realizes digital upgrading and transformation, and a sensing layer, a transmission layer and application layer equipment all adopt digital transmission. In a coal mine field, particularly an underground mine, wireless communication coverage is not provided, but for some special occasions, such as a goaf, a abandoned mine and the like, geology is changed frequently, a wired cable is easy to damage, the power supply and communication distance is too far, the cost is extremely high, and wireless communication is needed in a sensing layer. The LoRa technology has long communication distance and strong anti-interference capability, works in an ISM frequency band, can facilitate ad hoc networking, and does not need a wireless communication provider to support network coverage. The LoRaWan protocol can easily realize star-type architecture networking of LoRa equipment, but the original protocol downlink communication adopts FIFO mode scheduling, when a downlink frame is congested, a large amount of packet loss occurs, the channel utilization rate is low, and the transmission of key data of a sensing layer is not facilitated.
Disclosure of Invention
In view of this, the present invention provides a method for scheduling long-distance LoRa gateway downlink frames based on dynamic priority.
In order to achieve the purpose, the invention provides the following technical scheme:
a remote LoRa gateway downlink frame scheduling method based on dynamic priority comprises the following steps:
a. the structure of the method comprises a server, an LoRa gateway and a node, wherein the LoRa gateway is arranged between the server and the node and is in bidirectional communication with the server and the node respectively;
b. the method is applied to a LoRa network of a star architecture, the LoRa network follows a LoRaWAN protocol, and three modes of class A, class B and class C are supported on a physical layer;
c. the gateway comprises n independent radio frequency transmitting channels, each channel has the same hardware structure and performance, the gateway can simultaneously transmit n radio frequency signals, and the gateway uniformly schedules all the transmitting channels;
d. the gateway counts the success rate of downlink frame transmission of each activated node within a certain time, and dynamically divides the occupation priority of a transmission channel according to the power;
e. the gateway maintains an information table of the frame being sent, including the channel, rate, spreading factor and estimated completion time of the frame, for collision detection;
f. the gateway calculates the issuing time and the estimated time consumption of each downlink frame by taking the time of the gateway as a reference, maintains a downlink frame waiting list, and selects the downlink frame for sending for the optimal scheduling target by using the maximum transmitting channel utilization rate and the highest priority weighted sum, wherein the waiting list comprises the earliest starting time, the latest starting time, a channel, the speed, the spread spectrum factor and the estimated flight time information of the downlink frame.
Optionally, step b specifically includes:
the gateway downlink frame scheduling method is applied to a LoRa network of a star architecture, the LoRa network follows a LoRaWAN protocol, three modes of class A, class B and class C are supported on a physical layer, and nodes are all accessed to the network through the class A mode.
Optionally, step c specifically includes:
the gateway comprises n independent radio frequency transmitting channels, each channel has the same hardware structure and performance, the gateway can simultaneously transmit n radio frequency signals, n is larger than or equal to 1 and smaller than or equal to 8, the gateway uniformly schedules all the transmitting channels, and all the transmitting channels equally use the available channels planned under the ISM frequency band.
Optionally, step d specifically includes:
the gateway counts the success rate of sending downlink frames of each activated node, dynamically divides the occupation priority of the sending channel according to the power, and the higher the success rate is, the lower the priority is.
The dynamic division of priority is defined as: and updating the transmission success rate of the corresponding node immediately after transmitting or discarding one frame of data, and updating the priority of the next downlink frame of the node in real time.
Optionally, step e specifically includes:
the gateway maintains an information table of the frame being sent, wherein the information table comprises the channel, the rate, the spreading factor, the starting time and the estimated air time of the frame;
starting the temporal resolution to microseconds;
the estimated air time is calculated according to the formula (1):
T frame ＝T pre +T load (1)
in the formula, T pre For preamble transmission time estimation, T is calculated according to equation (2) load Calculating according to formula (3) for load transmission time estimation;
T pre ＝n preamble *T sym (2)
T load ＝n load *T sym (3)
in the formula, n preamble Is the number of preamble symbols, n load For the length of the payload symbol, T sym Calculating the time consumption of one symbol according to the formula (4);
T sym ＝2 SF /B bw (4)
wherein SF is a spreading factor, B bw Is the bandwidth.
Optionally, step f specifically includes: the gateway firstly selects the downlink frame to be sent according to the highest priority, and secondly selects the downlink frame to be sent according to the utilization rate of the maximized transmission channel.
Optionally, the transmit channel usage rate is defined as: the shorter the idle time of the transmitting channel is, the higher the utilization rate of the transmitting channel is; when a transmission channel is idle, the scheduler preferentially transmits frames with high priority, if a plurality of frames to be transmitted exist in the same priority, the frame with the highest utilization rate of the transmission channel is selected for transmission, and the smaller the difference value of the current time subtracted from the time to be transmitted is, the higher the utilization rate of the channel is.
The invention has the beneficial effects that: the invention provides a dynamic priority-based LoRa gateway downlink frame scheduling method, aiming at the problems that the channel utilization rate of a LoRaWAN protocol downlink frame scheduling algorithm is low when a network is busy and a terminal can not acquire a downlink frame all the time when the network is busy, so that the LoRa gateway downlink frame scheduling method can greatly improve the LoRa gateway downlink channel utilization rate and ensure that the terminal downlink frame fairly uses a transmitting channel when the network is busy.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
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For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic structural view of the present invention;
fig. 2 is a flowchart of downlink frame scheduling according to the present invention.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.
Please refer to fig. 1 to fig. 2, which are diagrams illustrating a method for scheduling downlink frames of a long-distance LoRa gateway based on dynamic priority.
FIG. 1 is a schematic structural view of the present invention; fig. 2 is a flow chart of downlink frame scheduling according to the present invention.
As shown in fig. 1 and 2, the method of the present embodiment includes:
a. the gateway downlink frame scheduling method is suitable for a LoRa network of a star architecture, follows a LoRaWAN protocol, and supports three modes of class A, class B and class C.
b. The gateway comprises n independent radio frequency transmitting channels, each channel has the same hardware structure and performance, the gateway can simultaneously transmit n radio frequency signals, and the gateway MCU uniformly schedules all the transmitting channels.
c. And the gateway MCU counts the sending success rate of the downlink frame of each activated terminal within a certain time, and dynamically divides the occupation priority of the sending channel according to the power.
d. The gateway maintains a table of information of frames being transmitted, including channel, rate, spreading factor, estimated completion time, etc. of the frames for collision detection.
e. The gateway calculates the issuing time and the estimated time consumption of each downlink frame by taking the time of the gateway as a reference, maintains a downlink frame waiting list which comprises the information of the earliest starting time, the latest starting time, a channel, the speed, the spread spectrum factor, the estimated flight time and the like of the downlink frame, and selects the issuing frame according to the highest priority firstly and selects the downlink frame to send according to the maximum transmitting channel utilization rate (the channel idle time is shortest) secondly.
In this embodiment, the downlink frame scheduling method in step a of the present invention is suitable for a LoRa network with a star architecture, follows a LoRaWAN protocol, and the gateway supports three modes, namely, class a, class B, and class C, and the terminal must support class a and may selectively support class B and class C.
The gateway in the step b comprises n independent radio frequency transmitting channels, each channel has the same hardware structure and performance, the gateway can simultaneously transmit n radio frequency signals, n is greater than or equal to 1 and less than or equal to 8, the gateway MCU uniformly schedules all the transmitting channels, and all the transmitting channels equally use the available channels planned under the ISM frequency band.
And c, the gateway counts the sending success rate of the downlink frame of each activated terminal within a certain time, dynamically divides the occupation priority of the issued channel according to the power, and the higher the success rate is, the lower the priority is. And updating the transmission success rate of the corresponding terminal immediately after processing a frame down-sending frame (transmission or discarding), and updating the priority of the next down-sending frame of the terminal in real time.
Step d the method maintains a list of information of the frames being transmitted, including channel, rate, spreading factor, start time, estimated air time, etc. of the frames for collision detection. All times are based on the system time of the gateway (the gateway may be in a closed space and all clocks maintained by the gateway), and the estimated air time of the frame is calculated as follows.
T frame ＝T pre +T load
T pre ＝n preamble *T sym
T load ＝n load *T sym
T sym ＝2 SF /B bw
And e, taking the gateway time as a reference, calculating the issuing time and the estimated time consumption of each downlink frame, maintaining a downlink frame waiting list which comprises the information of the earliest starting time, the latest starting time, channels, the speed, the spread spectrum factor, the estimated flight time and the like of the downlink frame, and selecting the downlink frame for sending for the optimal scheduling target by maximizing the utilization rate of the transmitting channel and the weighted sum of the highest priority. And for the issued frames which cannot be of the type, the issued time is calculated according to different formulas.
In this embodiment, for a frame of class A mode, the issuing time is T k ＝T up +T RECEIVE_DELAYn -T p -T frame ' calculation of formula.
In this embodiment, for the frame of class B mode, the issuing time is according to the formula T k ＝T beacon +T beacon_r +(k rand +n rand )*T slotlen And (4) calculating.
In this embodiment, for the class C mode frame, the issuing time is according to the formula T k ＞T up +T RECEIVE_DELAY1 And (4) calculating.
In this embodiment, the shorter the idle time of the transmission channel is, the higher the usage rate of the transmission channel is, when there is an idle transmission channel, the scheduler preferentially transmits a frame with a high priority, and if there are multiple frames to be transmitted in the same priority, selects the frame with the highest usage rate of the transmission channel to transmit.
The following is a detailed description of a specific example:
the first embodiment is as follows:
a LoRa gateway designed by a certain company adopts 8 SX1268 chips and is provided with 8 identical transceiving channels. The gateway counts the success rate of sending the downlink frame of each terminal in the last 10 minutes, and for the terminal with a communication period greater than 10 minutes, the success rate is counted according to 5 times of the communication period, the terminal is divided into 5 priorities according to the success rate of sending the downlink frame, and the priorities respectively correspond to the success rates from 0 to 20%, 20% to 40%, 40% to 60%, 60% to 80%, and 80% to 100% from high to low. The network manager maintains a frame sending table according to the priority, when a sending channel is idle, the dispatcher sends a frame with high priority preferentially, and if the same priority has a plurality of frames to be sent, the frame with the highest using rate of the sending channel is selected to be sent.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.
Claims (4)
1. A dynamic priority-based LoRa gateway downlink frame scheduling method is characterized in that: the method comprises the following steps:
a. the structure of the method comprises a server, an LoRa gateway and a node, wherein the LoRa gateway is arranged between the server and the node and is in bidirectional communication with the server and the node respectively;
b. the method is applied to a LoRa network of a star-shaped framework, the LoRa network follows a LoRaWAN protocol, and three modes of class A, class B and class C are supported on a physical layer;
c. the gateway comprises n independent radio frequency transmitting channels, each channel has the same hardware structure and performance, the gateway can simultaneously transmit n radio frequency signals, and the gateway uniformly schedules all the transmitting channels;
d. the gateway counts the success rate of downlink frame transmission of each activated node within a certain time, and dynamically divides the occupation priority of a transmission channel according to the power;
e. the gateway maintains an information table of the frame being sent, including the channel, rate, spreading factor and estimated completion time of the frame, for collision detection;
f. the gateway calculates the issuing time and the estimated time consumption of each downlink frame by taking the time of the gateway as a reference, maintains a downlink frame waiting list, and selects the downlink frame to send for the optimal scheduling target by maximizing the utilization rate of a transmitting channel and the weighted sum of the highest priority, wherein the waiting list comprises the earliest starting time, the latest starting time, a channel, the speed, the spread spectrum factor and the estimated flight time information of the downlink frame;
the step d is specifically as follows:
the gateway counts the success rate of sending downlink frames of each activated node, dynamically divides the occupation priority of a sending channel according to the power, and the higher the success rate is, the lower the priority is;
the dynamic division of the priority is defined as: updating the transmission success rate of the corresponding node immediately after transmitting or discarding one frame of data, and updating the priority of the next downlink frame of the node in real time;
the step e is specifically as follows:
the gateway maintains an information table of frames being transmitted, the information table including channel, rate, spreading factor, start time, estimated air time of the frames;
the start time resolution is to microseconds;
the estimated air time is calculated according to the formula (1):
T frame ＝T pre +T load (1)
in the formula, T pre For preamble transmission time estimation, T is calculated according to equation (2) load Calculating according to formula (3) for load transmission time estimation;
T pre ＝n preamble *T sym (2)
T load ＝n load *T sym (3)
in the formula, n preamble Is the number of preamble symbols, n load For the length of the payload symbol, T sym Calculating the time consumption of one symbol according to the formula (4);
T sym ＝2 SF /B bw (4)
wherein SF is a spreading factor, B bw Is the bandwidth;
the step f is specifically as follows: the gateway selects the downlink frame to be sent according to the highest priority firstly, and then selects the downlink frame to be sent according to the utilization rate of the maximized transmission channel.
2. The method for scheduling the downlink frames of the LoRa gateway based on the dynamic priority as claimed in claim 1, wherein: the step b is specifically as follows:
the gateway downlink frame scheduling method is applied to a LoRa network of a star architecture, the LoRa network follows a LoRaWAN protocol, three modes of class A, class B and class C are supported on a physical layer, and the nodes are all accessed to the network through the class A mode.
3. The method for scheduling the downlink frames of the LoRa gateway based on the dynamic priority as claimed in claim 1, wherein: the step c is specifically as follows:
the gateway comprises n independent radio frequency transmitting channels, each channel has the same hardware structure and performance, the gateway can simultaneously transmit n radio frequency signals, n is larger than or equal to 1 and smaller than or equal to 8, the gateway uniformly schedules all the transmitting channels, and all the transmitting channels equally use available channels planned under an ISM frequency band.
4. The method for scheduling the downlink frames of the LoRa gateway based on the dynamic priority as claimed in claim 1, wherein: the transmission channel utilization rate is defined as: the shorter the idle time of the transmitting channel is, the higher the utilization rate of the transmitting channel is; when a transmission channel is idle, the scheduler preferentially transmits a frame with high priority, if the same priority has a plurality of frames to be transmitted, the frame with the highest transmission channel utilization rate is selected for transmission, and the smaller the difference value of the current time subtracted from the time to be transmitted is, the higher the channel utilization rate is.
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| CN116634589B (en) * | 2023-07-25 | 2023-10-20 | 杭州微联智控科技有限公司 | Method for receiving and transmitting reliable messages of half-duplex LoRa network |
| CN117329341B (en) * | 2023-11-30 | 2024-02-09 | 河北乙木源节水科技有限公司 | Be applied to solar energy valve automatic control system of agriculture |
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