A dynamic transmission control method and system for floating LoRa network

Abstract

The present invention provides a dynamic transmission control method and system for a floating LoRa network, the method comprising the steps of: presetting an error probability threshold in the LoRa network, calculating a minimum signal-to-noise ratio according to the error probability threshold; calculating a first boundary angle according to the minimum signal-to-noise ratio, and obtaining a first angle interval; calculating data packet delivery rates and data rates corresponding to different spreading factors and polarization angles, calculating a maximum throughput, extracting an optimal polarization angle parameter and an optimal spreading factor parameter according to the maximum throughput, using the optimal polarization angle parameter as a second boundary angle, and calculating a second angle interval; calculating a transmission period according to the second angle interval, and calculating a data packet payload transmitted during the transmission period. The present application calculates a maximum throughput according to the data packet delivery rate and the data rate, finds a second angle interval, transmits in the second angle interval, improves transmission efficiency, calculates a data packet payload size according to the second angle interval, and transmits data in the second angle interval, preventing antenna posture from affecting transmission.

Description

Technical Field

[0001] The present invention relates to the technical field of Internet of Things, and in particular to a dynamic transmission control method and system of a floating LoRa network. Background Art

[0002] The Internet of Things (IoT) has shown significant development in terrestrial environments, including urban and rural areas. Thanks to the widespread deployment of low-power wide area networks (LPWANs) such as Long Range Radio (LoRa), recent studies are attempting to deploy IoT systems in aquatic environments such as oceans, reservoirs, and rivers. LoRa has the characteristics of wide coverage, high reliability, and low power consumption, and has great potential in supporting communications for floating nodes with anchors on the water surface.

[0003] However, compared to networks on land, floating LoRa networks experience significant degradation in link reliability, which can result in more than 20% drop in packet delivery rate (PDR). The reason for this is that floating nodes sway with the waves and have rapidly changing attitudes. The attitude changes can cause misalignment between the linearly polarized antennas of the LoRa transceiver, resulting in highly dynamic link signal-to-noise ratio (SNR) and subsequent packet failures. Unlike nodes on land with stable polarization alignment, the antenna attitude of floating nodes is constantly changing, resulting in unstable link quality and a non-negligible degradation in communication quality. Summary of the invention

[0004] In view of this, an embodiment of the present invention provides a dynamic transmission control method and system for a floating LoRa network to eliminate or improve one or more defects in the prior art.

[0005] One aspect of the present invention provides a dynamic transmission control method for a floating LoRa network, the method comprising the following steps:

[0006] An error probability threshold is preset in the floating node where the LoRa network is located, and the minimum signal-to-noise ratio corresponding to different spreading factor parameters is calculated according to the error probability threshold without exceeding the error probability threshold;

[0007] Calculating first boundary angles of different spreading factor parameters according to the minimum signal-to-noise ratio, and obtaining first angle intervals corresponding to the antenna under different spreading factor parameters according to the first boundary angle;

[0008] Extracting a polarization angle parameter within the first angle interval, where the polarization angle parameter is an angle value within the first angle interval, calculating a data packet delivery rate and a data rate according to the spreading factor parameter and the polarization angle parameter, calculating a throughput according to the data packet delivery rate and the data rate, substituting different spreading factor parameter and polarization angle parameter values, and taking a maximum throughput value among multiple groups of parameters;

[0009] Extracting an optimal polarization angle parameter and an optimal spreading factor parameter corresponding to the throughput according to the maximum throughput value, taking the optimal spreading factor parameter as the spreading factor parameter finally used, taking the optimal polarization angle parameter as the second boundary angle, and calculating a second angle interval according to the second boundary angle;

[0010] The transmission period is calculated according to the second angle interval, and the effective load size of the data packet transmitted in the transmission period is calculated, and the data packet is used to load and transmit data in the transmission period.

[0011] By adopting the above scheme, the present application first calculates the first angle interval in which the antenna can complete data transmission during the floating and swinging process, and then calculates the throughput according to the data packet delivery rate and the data rate, and the maximum throughput value, and finds the second angle interval corresponding to the maximum value, so that the antenna can transmit in the second angle interval to improve the transmission efficiency, and calculates the effective load of the data packet according to the second angle interval, so that the data is transmitted in the second angle interval to prevent the transmission from being affected by the antenna posture.

[0012] In some embodiments of the present invention, the steps of the dynamic transmission control method of the floating LoRa network further include data reorganization, and the step of data reorganization includes:

[0013] Determine whether the length of the received data is greater than the payload. If so, divide the data into multiple parts and load them into data packets of different cycles for transmission; if not, wait for the next data and load this data and the next data into the same data packet for transmission.

[0014] In some embodiments of the present invention, the error probability threshold is set to , the spreading factor is , the minimum signal-to-noise ratio is , the minimum signal-to-noise ratio is calculated according to the following formula:

[0015] ; Represents the tail function of the standard normal distribution.

[0016] In some embodiments of the present invention, the step of calculating the first boundary angle includes:

[0017] Environmental signal-to-noise ratio calculation: The antenna of the floating node transmits an experimental data packet, and the receiving end receives the experimental data packet and calculates the experimental signal-to-noise ratio when receiving the experimental data packet and the experimental polarization angle when the antenna transmits the experimental data packet. Suppose the experimental signal-to-noise ratio is , the experimental polarization angle is , the environmental signal-to-noise ratio is , the environmental signal-to-noise ratio is calculated according to the following formula:

[0018] ;

[0019] Let the first boundary angle be , the first boundary angle is calculated according to the following formula:

[0020] .

[0021] In some embodiments of the present invention, the first angle interval is .

[0022] In some embodiments of the present invention, the experimental signal-to-noise ratio is The calculation is based on the following formula:

[0023] ;

[0024] is the received power collected by the receiving antenna.

[0025] In some embodiments of the present invention, the received power collected by the receiving antenna The calculation is based on the following formula:

[0026] ;

[0027] is the antenna transmission power, is the transmitting antenna gain, is the receiving antenna gain, is the wavelength, is the distance between the transmitting antenna and the receiving antenna, is the polarization loss factor.

[0028] In some embodiments of the present invention, the structure of the LoRa data packet includes a preamble, a header and a payload, and the step of calculating the data packet delivery rate includes:

[0029] Calculate the preamble detection probability, header decoding probability and payload decoding probability respectively, and calculate the data packet delivery rate according to the preamble detection probability, header decoding probability and payload decoding probability. Suppose the preamble detection probability is , the header decoding probability is , the probability of payload decoding is , the packet delivery rate is , the data packet delivery rate is calculated according to the following formula:

[0030] .

[0031] In some embodiments of the present invention, is the symbol error probability under polarization effect, is the polarization angle,

[0032] Preamble detection probability The calculation is based on the following formula:

[0033] ;

[0034] Header decoding probability The calculation is based on the following formula:

[0035] , For a given header length;

[0036] Payload decoding probability The calculation is based on the following formula:

[0037] ;

[0038] is the load length, is the coding rate.

[0039] In some embodiments of the present invention, the data rate is set to , the data rate is calculated according to the following formula:

[0040] , It is the bandwidth.

[0041] In some embodiments of the present invention, let the throughput be A, the throughput is calculated according to the formula, A=DR*PDR, the maximum value of the throughput is calculated according to the three-point search method, and the second boundary angle corresponding to the maximum value is obtained. , the second angle interval is .

[0042] In some embodiments of the present invention, a period of the antenna swinging in the second angle interval is calculated according to the time the antenna swings in the second angle interval, and the period is set as the second period;

[0043] Assume the payload of the data packet is , the payload size of the data packet is calculated according to the following formula:

[0044] ;

[0045] For the second cycle, It is the duration of a single chirp signal in the LoRa channel.

[0046] In some embodiments of the present invention, The calculation is based on the following formula:

[0047] ; is the bandwidth, is the spreading factor.

[0048] In some embodiments of the present invention, the step of calculating the polarization angle of the antenna is to record the attitude change of the antenna, record the roll angle and pitch angle of the antenna in the change, and obtain the polarization angle of the antenna according to the Euler angle calculation method.

[0049] The polarization angle The calculation is based on the formula:

[0050] ;

[0051] is the roll angle, is the pitch angle.

[0052] In some embodiments of the present invention, the first boundary angle is calculated according to the following formula:

[0053] ;

[0054] is the first boundary angle when the extension factor is i, The first boundary angle when the spreading factor is j, is the minimum signal-to-noise ratio when the spreading factor is i, is the minimum signal-to-noise ratio when the spreading factor is j.

[0055] The dynamic transmission control method of the floating LoRa network of the present invention can first calculate the first angle interval in which the antenna can complete data transmission during the floating swing process, then calculate the throughput according to the data packet delivery rate and the data rate, the throughput maximum value, find the second angle interval corresponding to the maximum value, so that the antenna transmits in the second angle interval, improves the transmission efficiency, and calculates the effective load of the data packet according to the second angle interval, so that the data is transmitted in the second angle interval, and prevents the transmission from being affected by the antenna posture.

[0056] Additional advantages, purposes, and features of the present invention will be described in part in the following description, and will become apparent to those skilled in the art after studying the following, or may be learned from the practice of the present invention. The purposes and other advantages of the present invention can be specifically pointed out and obtained in the specification and the accompanying drawings.

[0057] Those skilled in the art will appreciate that the objectives and advantages that can be achieved with the present invention are not limited to the above specific description, and the above and other objectives that can be achieved by the present invention will be more clearly understood from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of this application, and do not constitute a limitation of the present invention.

[0059] Figure 1 It is a schematic diagram of a first embodiment of a dynamic transmission control method for a floating LoRa network of the present invention;

[0060] Figure 2 Schematic diagram of a second implementation of the dynamic transmission control method for a floating LoRa network of the present invention;

[0061] Figure 3 Schematic diagram of a third embodiment of the dynamic transmission control method for a floating LoRa network of the present invention;

[0062] Figure 4 This is an example diagram of the first calculation of the three-point search method;

[0063] Figure 5 This is an example diagram of the second calculation of the three-point search method;

[0064] Figure 6 This is an example diagram of the third calculation of the three-point search method;

[0065] Figure 7 (1) Schematic diagram of throughput corresponding to different angles under different spreading factor parameters when the signal-to-noise ratio is 0;

[0066] Figure 7 (2) Schematic diagram of throughput corresponding to different angles under different spreading factor parameters when the signal-to-noise ratio is -10;

[0067] Figure 8 Schematic diagram of the antenna in the second angle range. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0069] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions according to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0070] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, elements, steps or components, but does not exclude the presence or addition of one or more other features, elements, steps or components.

[0071] It should also be noted that, unless otherwise specified, the term “connection” herein may refer not only to a direct connection but also to an indirect connection involving an intermediate.

[0072] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

[0073] like Figure 1 As shown, one aspect of the present invention provides a dynamic transmission control method for a floating LoRa network, the method comprising the following steps:

[0074] Step S100, an error probability threshold is preset in the floating node where the LoRa network is located, and the minimum signal-to-noise ratio corresponding to different spreading factor parameters is calculated according to the error probability threshold without exceeding the error probability threshold;

[0075] In some embodiments of the present invention, the error probability threshold is the maximum error probability value that can be used to ensure successful transmission. The error probability threshold can be .

[0076] Step S200, calculating a first boundary angle of different spreading factor parameters according to the minimum signal-to-noise ratio, and obtaining a first angle interval corresponding to the antenna under different spreading factor parameters according to the first boundary angle;

[0077] The first angle interval is a swingable interval in which the antenna can complete data transmission during the floating swing process;

[0078] In some embodiments of the present invention, different spreading factor parameters correspond to different boundary angles, that is, the antenna can complete data transmission in different sway ranges using different spreading factor parameters; the first boundary angle is the angle between the antenna and the water surface when it swings to the edge of the first angle range.

[0079] Step S300, extracting a polarization angle parameter within the first angle interval, wherein the polarization angle parameter is an angle value within the first angle interval, calculating a data packet delivery rate and a data rate according to the spreading factor parameter and the polarization angle parameter, calculating a throughput according to the data packet delivery rate and the data rate, substituting different spreading factor parameter and polarization angle parameter values, and taking a maximum throughput value among multiple groups of parameters;

[0080] Step S400, extracting an optimal polarization angle parameter and an optimal spreading factor parameter corresponding to the throughput according to the maximum throughput, taking the optimal spreading factor parameter as the spreading factor parameter finally used, taking the optimal polarization angle parameter as the second boundary angle, and calculating a second angle interval according to the second boundary angle;

[0081] In some embodiments of the present invention, each group of different data packet delivery rates and data rates corresponds to different throughput values. The present application traverses all combinations of data packet delivery rates and data rates to find the combination of data packet delivery rates and data rates with the largest throughput. After finding the polarization angle used by the combination, the polarization angle is the optimal polarization angle parameter. The polarization angle is used as a new boundary angle, and the throughput is used to re-define the second boundary angle within the first angle range to ensure the throughput of data transmission.

[0082] Step S500, calculating a transmission period according to a second angle interval, and calculating a payload size of a data packet transmitted in the transmission period, wherein the data packet is used to load and transmit data in the transmission period.

[0083] The transmission period is a period during which the antenna swings in the second angle range.

[0084] In some embodiments of the present invention, the antenna is installed on the transmission node, and the period of the antenna's swing in the second angle range can be captured by installing an inertial sensor (IMU, Inertial Measurement Unit) on the transmission node to capture the attitude change of the transmitting antenna. The sampling rate of the IMU is 200 Hz. We can obtain an attitude angle measurement every 5 milliseconds, which can fully describe the antenna's attitude movement and calculate the period of the swing in the second angle range by recording the time.

[0085] In some embodiments of the present invention, the transmission node may be an object floating on the water surface.

[0086] By adopting the above scheme, the present application first calculates the first angle interval in which the antenna can complete data transmission during the floating and swinging process, and then calculates the throughput according to the data packet delivery rate and the data rate, and the maximum throughput value, and finds the second angle interval corresponding to the maximum value, so that the antenna can transmit in the second angle interval, thereby improving the transmission efficiency, and according to the effective load size calculated in the second angle interval, the data is transmitted in the second angle interval to prevent the transmission from being affected by the antenna posture.

[0087] like Figure 4-6 As shown, in some embodiments of the present invention, the method of calculating the maximum throughput can be implemented by a three-part search algorithm, which is an algorithm that can find the maximum or minimum search problem of a unimodal function. Specifically, we first divide the first angle interval into three parts evenly. Given two intersection points between the three parts, we will compare the estimated throughputs of the two angles at the intersection. The search space is narrowed by abandoning the side part with a smaller metric. Repeat this process until the range of the search space is less than a specific value and the maximum value is obtained.

[0088] The steps of the three-part search algorithm include:

[0089] like Figure 4 As shown, the horizontal axis is the angle of the first angle interval, and the vertical axis is The first angle interval is divided into three equal parts, with the overall boundaries being left and right, and the two intersection points being m1 and m2. , remove the interval on the smaller side and regard the smaller three-point as the boundary. That is, if m1 is smaller, remove [left,m1) and set m1 to left; if m2 is smaller, remove (m2,right] and set m2 to right;

[0090] Figure 4 In the figure, m2 is small, so remove (m2, right] to form Figure 5 ;

[0091] Repeat the above steps to divide the new overall interval into three parts again, and compare the boundary points m1 and m2. The size of , remove the smaller interval again, remove Figure 5 (m2,right], forming Figure 6 ;

[0092] Three more times, remove Figure 6 [left,m1) in;

[0093] Repeat the above steps until the length of the interval [left, right] is less than a pre-set threshold. This interval can be roughly regarded as a point, and we have found The maximum value, that is, left or right The value of .

[0094] like Figure 2 As shown, in some embodiments of the present invention, the steps of the dynamic transmission control method of the floating LoRa network also include step S600, data reorganization, and the step of data reorganization includes:

[0095] Determine whether the length of the received data is greater than the payload. If so, divide the data into multiple parts and load them into data packets of different cycles for transmission; if not, wait for the next data and load this data and the next data into the same data packet for transmission.

[0096] In some embodiments of the present invention, the error probability threshold is set to , the spreading factor is , the minimum signal-to-noise ratio is , the minimum signal-to-noise ratio is calculated according to the following formula:

[0097] ;

[0098] The above formula can be applied to the additive white Gaussian noise (AWGN) channel.

[0099] The error probability threshold is Can be .

[0100] like Figure 3 As shown, in some embodiments of the present invention, the dynamic transmission control method of the floating LoRa network further includes step S700, parameter updating, and the parameter updating step includes:

[0101] monitoring the throughput of the transmission node in real time and receiving a throughput attenuation threshold;

[0102] If the real-time attenuation of the throughput is greater than the attenuation threshold;

[0103] Repeat steps S200-S400 to reset the second angle interval, the optimal spreading factor parameter and the payload of the data packet;

[0104] If not, continue the transmission.

[0105] Using the above solution, due to the complex marine environment and the rapid changes in the environmental signal-to-noise ratio, this application monitors the throughput of the transmission node. If the throughput decays over a large range, it means that the parameters need to be updated to ensure the node transmission capacity.

[0106] In some embodiments of the present invention, the step of calculating the first boundary angle includes:

[0107] Environmental signal-to-noise ratio calculation: The antenna of the floating node transmits an experimental data packet, and the receiving end receives the experimental data packet and calculates the experimental signal-to-noise ratio when receiving the experimental data packet and the experimental polarization angle when the antenna transmits the experimental data packet. Suppose the experimental signal-to-noise ratio is , the experimental polarization angle is , the environmental signal-to-noise ratio is , the environmental signal-to-noise ratio is calculated according to the following formula:

[0108] ;

[0109] Let the first boundary angle be , the first boundary angle is calculated according to the following formula:

[0110] .

[0111] In some embodiments of the present invention, the first angle interval is .

[0112] In some embodiments of the present invention, the experimental signal-to-noise ratio is The calculation is based on the following formula:

[0113] ;

[0114] is the received power collected by the receiving antenna.

[0115] In some embodiments of the present invention, the present application pre-transmits at least one experimental data packet, a node sends several short data packets and records the corresponding experimental polarization angle and experimental signal-to-noise ratio. The node can obtain relevant data from the feedback of the base station.

[0116] In some embodiments of the present invention, the received power collected by the receiving antenna The calculation is based on the following formula:

[0117] ;

[0118] is the antenna transmission power, is the transmitting antenna gain, is the receiving antenna gain, is the wavelength, is the distance between the transmitting antenna and the receiving antenna, is the polarization loss factor.

[0119] The above formula is a conversion formula that incorporates the polarization state into the Friis transmission formula (Friis).

[0120] In some embodiments of the present invention, the structure of the LoRa data packet includes a preamble, a header and a payload, and the step of calculating the data packet delivery rate includes:

[0121] Calculate the preamble detection probability, header decoding probability and payload decoding probability respectively, and calculate the data packet delivery rate according to the preamble detection probability, header decoding probability and payload decoding probability. Suppose the preamble detection probability is , the header decoding probability is , the probability of payload decoding is , the packet delivery rate is , the data packet delivery rate is calculated according to the following formula:

[0122] .

[0123] In some embodiments of the present invention, is the symbol error probability under polarization effect, is the polarization angle,

[0124] Preamble detection probability The calculation is based on the following formula:

[0125] ;

[0126] Header decoding probability The calculation is based on the following formula:

[0127] , For a given header length;

[0128] Payload decoding probability The calculation is based on the following formula:

[0129] ;

[0130] is the load length, is the coding rate.

[0131] In some embodiments of the present invention, the LoRa preamble generally includes an 8-symbol preamble, a 4.25-symbol mandatory preamble, and the 4.25-symbol mandatory preamble includes a 2-symbol synchronization word and a 2.25-frame start symbol (SFD, Start of Framedelimiter). Since the preamble is detected by correlation, the process can be regarded as receiving a symbol modulated with a SF of (SF+8+2+2.25), i.e., SF+12.25.

[0132] In some embodiments of the present invention, in practical applications, reliability and throughput are usually used to consider the transmission capability of a node, wherein reliability is usually measured by a packet delivery ratio (PDR).

[0133] This design actively controls the transmission configuration, including transmission timing, SF, and packet length. For practical reasons, we do not control parameters such as transmission power (TP) and BW. Adjusting the BW of a single node will cause unpredictable interference to the entire network. In a floating LoRa network, frequent changes in TP will affect the power supply plan of the node itself and the overall node coverage plan. In this section, we first estimate the reliability and throughput, and then seek and apply the transmission configuration with the highest transmission efficiency.

[0134] In some embodiments of the present invention, the data rate is set to , the data rate is calculated according to the following formula:

[0135] , It is the bandwidth.

[0136] In some embodiments of the present invention, let the throughput be A, the throughput is calculated according to the formula, A=DR*PDR, the maximum value of the throughput is calculated according to the three-point search method, and the second boundary angle corresponding to the maximum value is obtained. , the second angle interval is .

[0137] In actual implementation, due to computational limitations, the three-way search consumes up to about 0.5 seconds on a LoRa node. If the three-way search is used every time the best alignment SNR changes, the cost is too high. Since the SNR of the best alignment does not change frequently, we can use periodic configuration selection or trigger configuration selection when the environment changes significantly. In our current implementation, we calculate the best configuration regularly every 30 seconds. In order to avoid the three-way search delaying the timing of data packet transmission, we schedule the three-way search to the unaligned period when computing resources are idle.

[0138] In some embodiments of the present invention, a period of the antenna swinging in the second angle interval is calculated according to the time the antenna swings in the second angle interval, and the period is set as the second period;

[0139] Assume the payload of the data packet is , the payload size of the data packet is calculated according to the following formula:

[0140] ;

[0141] For the second cycle, It is the duration of a single chirp signal in the LoRa channel.

[0142] The above data packet payload calculation formula is derived by combining the following two formulas:

[0143] ; PL is the length of the data packet, CRC is the cyclic redundancy check parameter, is the number of symbols in the payload;

[0144] ; is the packet duration.

[0145] In some embodiments of the present invention, the inertial sensor recorded Substitute into the formula of .

[0146] In some embodiments of the present invention, The calculation is based on the following formula:

[0147] ; is the bandwidth, is the spreading factor.

[0148] In LoRa, each chirp consists of a When the bandwidth is BW, the duration of a single chirp It can be calculated as .

[0149] In some embodiments of the present invention, the step of calculating the polarization angle of the antenna is to record the attitude change of the antenna, record the roll angle and pitch angle of the antenna in the change, and obtain the polarization angle of the antenna according to the Euler angle calculation method.

[0150] The polarization angle The calculation is based on the formula:

[0151] ;

[0152] is the roll angle, is the pitch angle.

[0153] The roll angle and the pitch angle are both captured and collected by the inertial sensor.

[0154] In some embodiments of the present invention, the steps of the dynamic transmission control method of the floating LoRa network also include fast first boundary angle calculation according to the following formula:

[0155] ;

[0156] is the first boundary angle when the extension factor is i, The first boundary angle when the spreading factor is j, is the minimum signal-to-noise ratio when the spreading factor is i, is the minimum signal-to-noise ratio when the spreading factor is j. After the data packet is packaged, the data packet scheduling management will start loading the data packet before the scheduled transmission start time due to software and hardware delays. According to our practice, the time difference between the start of transmission and the time when the data packet is transmitted in the air is about 0.2s. If hardware and software delays are ignored, the scheduled transmission cycle will not match the actual transmission cycle. The latter part of the data packet may still fall on a period that is assumed to be idle, resulting in reduced reliability. Therefore, in order to avoid the adverse effects of delays, we load the data packet into the buffer before the scheduled transmission start time to align with the desired transmission cycle. As long as it is recognized that the node antenna is currently in the transmission cycle, the data packet can be transmitted immediately to adapt to the aligned cycle.

[0157] Steps S200-S400 of the present application are all processes of establishing a model, simulating the swaying of the antenna on the water surface as a periodic motion, and establishing a V-zone model, that is, a V-shaped model, with the motion.

[0158] like Figure 8 As shown, Figure 8 Schematic diagram of a V-shaped model, where θ1 is the second boundary angle, θ2 is the first boundary angle, the angle interval where δ is located is the second angle interval, and node represents a node equipped with an antenna.

[0159] like Figure 7 As shown in (1) and (2), Figure 7 The horizontal axis of (1) and (2) is the polarization angle, and the vertical axis is the throughput. Figure 7 The maximum point marked in the figure is the point with the maximum throughput, and the optimal angle indicates the optimal angle corresponding to the maximum throughput point. Different spreading factors have different throughputs at different polarization angles. Therefore, it is very important to select the optimal spreading factor parameter.

[0160] The angle indicated in the present application may be a polarization angle in the second angle interval or the first angle interval, or may be an angle that cannot be transmitted outside the first angle interval.

[0161] Adaptive control is a conventional method for handling link dynamics in the prior art, including adaptive data rate (ADR) and DyLoRa. ADR is a dynamic parameter adjustment officially provided by LoRaWAN to provide different data rates, but it cannot adapt to the dynamic swaying posture on the water. The prior art focuses on controlling transmission parameters to obtain better PDR. The link quality is evaluated by the quality of recent transmissions, and the corresponding transmission parameters are adjusted to adapt to the environment. Existing adaptive methods cannot protect the transmission reliability of floating LoRa networks because they only focus on occasional changes in link attenuation and ignore the rapidly changing link quality caused by polarization alignment. Due to the constant changes in the aquatic environment, the signal-to-noise ratio (SNR) estimated from the gateway can even change by 6dB in one second, and the parameter settings determined based on historical information are difficult to adapt to the rapidly changing link quality.

[0162] PolarTracker, a state-of-the-art method, is the first to address the problem of attitude link degradation in floating LoRa networks. It can improve reliability by scheduling data packets to start transmission from the aligned attitude. In practical applications, PolarTracker models the transmission quality of nodes in a swaying state through the signal quality feedback from the gateway. It estimates the transmission quality at the next moment to determine whether the next moment is a reasonable transmission opportunity, and schedules data packets accordingly, thereby solving the problem of link quality changes in a floating state.

[0163] However, PolarTracker ignores the polarization alignment period length and only controls the transmission start time, which still results in poor performance. First, due to the mismatch between the packet duration and the alignment period, the reliability of the transmission may not be guaranteed. For floating LoRa networks that require long communication distances, it is very common to use a larger SF value. However, our measurements show that when LoRa uses a larger SF value, the signal-to-noise ratio can vary by 8dB during the transmission of a packet, which means that the latter part of the packet will be transmitted during the misalignment period, causing the entire packet to fail. Second, when the duration of the sent packet is shorter than the alignment period, the alignment period is not fully utilized. Since PolarTracker only schedules packets with predetermined transmission configurations, the mismatch between the packet duration and the dynamic alignment period leads to low throughput.

[0164] The dynamic alignment period is the second period, that is, PolarTracker cannot guarantee that the data packet is transmitted within the second period.

[0165] The data packet transmission time of the present application corresponds to the swing period, which solves the problem that the data packet transmission time does not correspond to the alignment period (ie, the swing period).

[0166] Corresponding to the above method, the present invention also provides a dynamic transmission control system of a floating LoRa network, the system comprising a computer device, the computer device comprising a processor and a memory, the memory storing computer instructions, the processor being used to execute the computer instructions stored in the memory, and when the computer instructions are executed by the processor, the device / system implements the steps of the method described above.

[0167] The embodiment of the present invention also provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the steps of the dynamic transmission control method of the floating LoRa network are implemented. The computer-readable storage medium can be a tangible storage medium, such as a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a floppy disk, a hard disk, a removable storage disk, a CD-ROM, or any other form of storage medium known in the technical field.

[0168] It should be understood by those skilled in the art that the exemplary components, systems and methods described in conjunction with the embodiments disclosed herein can be implemented in hardware, software or a combination of the two. Whether it is performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention. When implemented in hardware, it can be, for example, an electronic circuit, an application-specific integrated circuit (ASIC), appropriate firmware, a plug-in, a function card, etc. When implemented in software, the elements of the present invention are programs or code segments used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or a communication link via a data signal carried in a carrier.

[0169] It should be clear that the present invention is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known method is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present invention.

[0170] In the present invention, features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with features of other embodiments or replace features of other embodiments.

[0171] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A dynamic transmission control method for a floating LoRa network, characterized in that: The method comprises the following steps: Preset an error probability threshold, and calculate, according to the error probability threshold, the minimum signal-to-noise ratio corresponding to different spreading factor parameters when the error probability threshold is not greater than the error probability threshold; Calculate the first boundary angle of different spreading factor parameters according to the minimum signal-to-noise ratio, and obtain the first angle interval corresponding to the antenna under different spreading factor parameters according to the first boundary angle, wherein the first angle interval is the swing interval in which the antenna can complete data transmission during the floating swing process, and the first boundary angle is the angle between the antenna and the water surface when the antenna swings to the edge of the first angle interval; Extracting a polarization angle parameter within the first angle interval, where the polarization angle parameter is an angle value within the first angle interval, calculating a data packet delivery rate and a data rate according to the spreading factor parameter and the polarization angle parameter, calculating a throughput according to the data packet delivery rate and the data rate, substituting different spreading factor parameter and polarization angle parameter values, and taking a maximum throughput value among multiple groups of parameters; Extracting an optimal polarization angle parameter and an optimal spreading factor parameter corresponding to the throughput according to the maximum throughput value, taking the optimal spreading factor parameter as the spreading factor parameter finally used, taking the optimal polarization angle parameter as the second boundary angle, and calculating a second angle interval according to the second boundary angle; The transmission period is calculated according to the second angle interval, the transmission period is the period of the antenna swinging in the second angle interval, and the effective load size of the data packet transmitted in the transmission period is calculated. The data packet is used to load and transmit data in the transmission period.

2. The method according to claim 1, characterized in that The steps of the dynamic transmission control method of the floating LoRa network also include data reorganization, and the step of data reorganization includes: Determine whether the length of the received data is greater than the data packet length. If so, divide the data into multiple parts and load them into data packets of different cycles for transmission; if not, wait for the next data and load this data and the next data into the same data packet for transmission.

3. The method according to claim 1 or 2, characterized in that The error probability threshold is , the spreading factor is , the minimum signal-to-noise ratio is , the minimum signal-to-noise ratio is calculated according to the following formula: , Represents the tail function of the standard normal distribution.

4. The method according to claim 3, characterized in that The step of calculating the first boundary angle comprises: Environmental signal-to-noise ratio calculation, receiving the experimental polarization angle calculated by the receiving end, assuming the experimental signal-to-noise ratio is , the experimental polarization angle is , the environmental signal-to-noise ratio is , the environmental signal-to-noise ratio is calculated according to the following formula: ； Let the first boundary angle be , the first boundary angle is calculated according to the following formula: 。 5. The method according to claim 4, characterized in that The structure of the LoRa data packet includes a preamble, a header and a payload, and the steps for calculating the data packet delivery rate include: Calculate the preamble detection probability, header decoding probability and payload decoding probability respectively, and calculate the data packet delivery rate according to the preamble detection probability, header decoding probability and payload decoding probability. Suppose the preamble detection probability is , the header decoding probability is , the probability of payload decoding is , the packet delivery rate is , the data packet delivery rate is calculated according to the following formula: ； set up is the symbol error probability under polarization effect, is the polarization angle, Preamble detection probability The calculation is based on the following formula: ； Header decoding probability The calculation is based on the following formula: , For a given header length; Payload decoding probability The calculation is based on the following formula: ； is the load length, is the coding rate.

6. The method according to claim 5, characterized in that The data rate is , the data rate is calculated according to the following formula: , It is the bandwidth.

7. The method according to claim 6, characterized in that Assume that the throughput is A, and the throughput is calculated according to the formula, A=DR*PDR. The maximum value of the throughput is calculated according to the three-point search method, and the second boundary angle corresponding to the maximum value is obtained. , the second angle interval is .

8. The method according to claim 7, characterized in that Calculate the period of the antenna swinging in the second angle interval according to the time the antenna swings in the second angle interval, and set the period as the second period; Assume the payload of the data packet is , the payload size of the data packet is calculated according to the following formula: ； For the second cycle, It is the duration of a single chirp signal in the LoRa channel.

9. The method according to claim 1, 2 or 8, characterized in that: The first boundary angle is calculated according to the following formula: ； is the first boundary angle when the extension factor is i, The first boundary angle when the spreading factor is j, is the minimum signal-to-noise ratio when the spreading factor is i, is the minimum signal-to-noise ratio when the spreading factor is j.

10. A dynamic transmission control system for a floating LoRa network, comprising a processor and a memory, characterized in that: The memory stores computer instructions, and the processor is used to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor, the system implements the steps of the method as claimed in any one of claims 1 to 9.

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