CN117956422A

CN117956422A - Low-rate self-adaptive optimized LoRa data receiving and transmitting control method and system

Info

Publication number: CN117956422A
Application number: CN202311583271.XA
Authority: CN
Inventors: 林和昀; 张志海; 韦龙坤; 蔡晓兰; 唐元; 蒋烨; 阳佑敏; 罗轩; 李克键; 王刚; 林光正
Original assignee: Guangxi Power Grid Co Ltd
Current assignee: Guangxi Power Grid Co Ltd
Priority date: 2023-11-24
Filing date: 2023-11-24
Publication date: 2024-04-30

Abstract

The invention discloses a low-rate self-adaptive optimized LoRa data receiving and transmitting control method and a system, wherein the method comprises the following steps: initializing and configuring radio frequency parameters of LoRa; performing mode switching according to the event-triggered condition and the current state; initializing a data type list; setting different service data types, or carrying out correlation detection on the service data, and updating a data type list based on the different service data types; selecting a corresponding data compression algorithm according to different service data types to perform data compression; carrying out LoRa data transmission on the compressed data based on RBAR rate self-adaptive optimization algorithm; based on RTS/CTS mechanism, through sending RTS message and receiving CTS message, coordinating sending end and receiving end select optimal sending spread spectrum factor and receiving window, completed LoRa data transmission process. The invention can effectively improve the LoRa emission rate and the bandwidth utilization rate.

Description

Low-rate self-adaptive optimized LoRa data receiving and transmitting control method and system

Technical Field

The invention relates to the technical field of wireless communication, in particular to a low-rate self-adaptive optimized LoRa data receiving and transmitting control method and system.

Background

The wireless communication technology plays a crucial role in the application of the internet of things, the technology of the internet of things relates to large-scale equipment connection and data transmission, a reliable, efficient and energy-saving communication mode is needed, and in the internet of things, data exchange and remote control between equipment are realized by physical network equipment through the wireless communication technology.

The wireless Communication technology has various choices in the internet of things, including Bluetooth (Bluetooth), wi-Fi, zigbee, NFC (NEAR FIELD Communication) and the like, and the technologies have different characteristics and application scenes; of these wireless communication technologies, loRa (Long Range) technology has been attracting attention because of its long range and low power consumption, and LoRa has a longer communication range than some conventional wireless communication technologies such as bluetooth and Wi-Fi. The LoRa technology can realize communication distance of several kilometers in urban environment, and can provide reliable communication connection even in rural areas or mountain areas and other wide areas, so that the LoRa is an ideal choice for connecting distributed equipment or wide area internet of things application.

The LoRa technology adopts the design of ultra-low power consumption in communication, so that the Internet of things equipment can work in a long-time mode, and can be powered by a battery, so that the frequency of maintenance and battery replacement is reduced; meanwhile, the LoRa has strong anti-interference capability because of a specially designed spread spectrum modulation technology, can keep communication quality under the condition that a large amount of other wireless devices interfere, and by virtue of the advantages, the LoRa is a powerful choice in the application of the Internet of things, especially in the application of a wireless sensor network, and is expected to play a larger role in various fields, such as intelligent cities, agricultural monitoring, industrial automation and the like, along with the development of the Internet of things and the increase of application scenes.

However, due to the design principle and application situation, the LoRa technology is relatively low in terms of transmission rate, and firstly, the LoRa adopts a low-power spread spectrum modulation scheme, long-distance transmission is realized by carrying out signal spreading on a wider frequency bandwidth, and the spread spectrum modulation scheme can improve the anti-interference capability and transmission distance of signals, but sacrifices the transmission rate. The transmission rate of LoRa is lower compared to other high-speed modulation schemes, such as Frequency Modulation (FM) or orthogonal frequency division multiple access (OFDM); second, the communication bandwidth of the LoRa is relatively narrow, typically in the range of 125kHz, 250kHz, or 500kHz, with the narrow bandwidth limiting the available spectrum resources and thus affecting the transmission rate; a wider bandwidth may generally provide a higher transmission rate, but may increase power consumption and reduce transmission distance. A key advantage of the LoRa technology is that it enables long range transmission, and there is a trade-off between transmission distance and transmission rate, and in order to achieve longer transmission distances, the LoRa technology generally uses a lower transmission rate, because at lower transmission rates, signals are transmitted over longer time windows, which can better overcome multipath fading and interference in other wireless channels.

Based on the above description, although the transmission rate of the LoRa is relatively low, it is still very practical in many applications of the internet of things, so optimizing the LoRa rate is necessary for some applications of the internet of things, it can provide faster data transmission, increase throughput and flexibility of the system, thereby meeting the requirements in different application scenarios, but how to design a corresponding data transmission strategy and parameter adaptive optimization method for the LoRa technology, and further effectively improve the LoRa transmission rate is a problem to be solved.

Disclosure of Invention

In order to overcome the defects and shortcomings of the prior art, the invention provides a low-rate self-adaptive optimized LoRa data receiving and transmitting control method and system.

In order to achieve the above purpose, the present invention adopts the following technical scheme:

The invention provides a low-rate self-adaptive optimized LoRa data receiving and transmitting control method, which comprises the following steps:

initializing and configuring radio frequency parameters of LoRa communication equipment;

Initializing a state machine of the LoRa data transceiver, wherein the LoRa data transceiver is driven by the finite state machine, and performing mode switching according to the event-triggered condition and the current state;

initializing a data type list;

setting different service data types or carrying out correlation detection on service data to obtain different service data types, and updating a data type list based on the different service data types;

selecting corresponding data compression algorithms according to different service data types to compress the data, and obtaining compressed data;

Inputting the compressed data to a LoRa data transceiver, and carrying out LoRa data transmission based on RBAR rate self-adaptive optimization algorithm;

based on RTS/CTS mechanism, through sending RTS message and receiving CTS message, coordinating sending end and receiving end select optimal sending spread spectrum factor and receiving window, completed LoRa data transmission process.

As a preferred technical solution, the initializing configuration of the radio frequency parameters of the LoRa communication device specifically includes: initializing a register structure and a register pointer, acquiring all initialization values of radio frequency parameters, setting the center frequency of data transmission, setting the spread spectrum factors of data transmission and reception, setting the error correction code length of data transmission and reception, setting the bandwidth size of data transmission and reception, setting a CRC (cyclic redundancy check) mode and setting a header mode.

As a preferable technical scheme, the data types comprise a weak correlation data type and a strong correlation data type, if the data type is judged to be the weak correlation data type, a CDCA-1 algorithm is adopted for data compression, if the data type is judged to be the strong correlation data type, a CDCA-2 algorithm is adopted for data compression, the CDCA-1 algorithm is combined with extrapolation prediction and a bit aggregation technology for data compression, and the CDCA-2 algorithm is combined with a run-length coding mode for data compression by using a difference coding.

As a preferable technical scheme, the CDCA-1 algorithm is adopted for data compression, and the specific steps comprise:

acquiring a symbol, and converting a data value into a decimal value based on a positive number;

By a power of 10, converting the positive number-based decimal value to a positive number-based integer value, and converting the positive number-based integer value to a digital-based binary representation;

the complete value of the first measurement data transmitted in each round is reserved and used as the starting point of the transmission task of the round;

the coding starts from the second measured data value of each transmission round, and specifically comprises the following steps:

Predicting the measured data by using an extrapolation prediction algorithm to obtain an extrapolation predicted value;

Performing an XOR operation on the difference value between the second measured data value and the third measured data value and the previous measured data value of the second measured data value and the third measured data value to obtain a difference value, starting from the fourth measured data value, performing an XOR operation on the true value and the extrapolated predicted value, and performing binary data comparison to obtain a difference value of the two values;

encoding the difference sequence using a Huffman algorithm;

And aggregating the data by using a bit aggregation technology, dividing the data to be transmitted into blocks according to bytes, circularly moving the data sequence to the leftmost side, and carrying out bit aggregation among the bytes.

As a preferable technical scheme, the CDCA-2 algorithm is adopted for data compression, and the specific steps comprise:

Comparing binary data from the second measured data value by applying an XOR operation to obtain a difference value of the two values;

If any consecutive value is determined to be "0", only an instance of the previous value and the number of repetitions is sent;

As a preferred technical solution, the LoRa data transceiver is driven by a finite state machine, and performs mode switching according to an event-triggered condition and a current state, and specifically includes:

When the receiving event is judged to be triggered, switching to a receiving mode, in the receiving mode, executing signal detection, screening out useful signals, carrying out signal demodulation on the useful signals, and carrying out data decoding after demodulating out useful data streams to obtain a final data packet;

when the sending event is triggered, switching to a sending mode, in the sending mode, executing channel coding of a data packet to be sent, carrying out data modulation on the coded binary stream, and executing physical layer sending operation;

when the channel activity detection is determined to be executed, switching to a CAD mode, and monitoring a channel and detecting whether other devices are transmitting data in the CAD mode;

And when the low power consumption state is judged to be executed, switching to a sleep mode, and starting a timer to wake up the equipment after the preset time in the sleep mode or waking up the equipment according to an external trigger event.

As a preferred technical solution, when it is determined that the reception event is triggered, switching to the reception mode specifically includes:

setting a reception completion interrupt flag mask to capture a reception event while clearing a previous interrupt flag;

Checking whether a frequency hopping function is started in LoRa setting;

setting the LoRa to a single reception if the RX single mode is enabled in the LoRa setting, otherwise, setting the LoRa to a cyclic reception mode;

Setting a received data buffer address, setting a data buffer address pointer as an Rx base address, and writing the data buffer address pointer into a register;

Clearing a received data buffer area and starting a receiving timeout timer;

Switching the mode to a receiving execution mode and circularly detecting an interrupt register;

Clearing the receiving completion interrupt mark and switching the mode to the receiving completion mode when the receiving completion mark bit is detected, and updating a receiving timeout timer;

performing CRC (cyclic redundancy check) on the received data in the receiving completion mode, if the CRC is successful, writing the received data into a receiving data buffer area, and returning a receiving completion result;

if the mode is the RX single receiving mode, detecting whether the receiving time is overtime, switching the mode to the receiving time-out mode and returning a receiving time-out result when the receiving time is overtime;

when the sending event is judged to be triggered, switching to a sending mode specifically comprises the following steps:

Checking whether a frequency hopping function is started in LoRa setting;

setting a transmission completion flag interrupt flag mask to capture a transmission completion event;

Setting the data load length;

Setting the transmission direction of a data buffer area;

setting an address pointer of a data buffer area;

Writing the data load buffer area into a LoRa module, and setting a LoRa mode as a transmission mode;

Switching the mode to a transmission execution mode, and circularly detecting an interrupt register;

switching to a transmission completion mode if the transmission completion mark is detected, and returning to transmission failure if the transmission completion interrupt mark is not detected after timeout;

when it is determined that channel activity detection needs to be performed, switching to a CAD mode specifically includes:

setting a monitoring completion flag interrupt flag mask to capture CAD monitoring completion events;

Setting a working mode as a CAD monitoring execution mode, and circularly detecting an interrupt register;

And judging the current channel state after detecting that the CAD monitoring is finished, switching the working mode to the receiving mode to execute data receiving if the current channel is active, and returning a channel idle result if the current channel is idle.

As a preferred technical solution, the method for detecting correlation of service data includes:

Presetting a correlation threshold, detecting N pieces of input business data one by one, setting the number of effective data as M, adding one to the number of effective data M every time new data which is different from the last data is acquired, judging the size relation between the final M/N and the preset correlation threshold, and updating a data type list.

As a preferred technical solution, the coordination transmitting end and the receiving end select the optimal transmitting spreading factor and the receiving window, and the completed LoRa data transmission process specifically includes:

Before sending a data packet, a sending end sends a Request To Send (RTS) message to a receiving end;

After receiving the RTS message, the receiving end acquires the signal-to-noise ratio of the channel, selects a nearest demodulation signal-to-noise ratio according to the signal-to-noise ratio of the received data packet based on a preset demodulation signal-to-noise ratio threshold, and determines the optimal transmission spread spectrum factor of the corresponding transmitting end;

The receiving end adds the optimal transmission spread spectrum factor into the clear-to-send (CTS) message and sends the CTS message to the sending end, and meanwhile, the receiving end enters a set receiving window according to the optimal transmission spread spectrum factor, receives a data packet or resumes a default spread spectrum factor receiving state after waiting for the receiving window to finish;

The sending end extracts the optimal sending spread spectrum factor information in the CTS message, and uses the spread spectrum factor information to transmit a data packet to the receiving end, after the transmission is completed, the sending end resumes the spread spectrum factor setting, and at the same time, other nodes enter a silence window after receiving the CTS message.

The invention also provides a low-rate self-adaptive optimized LoRa data receiving and transmitting control system, which comprises: the system comprises an initialization configuration module, a mode switching module, a data type list initialization module, a data type list updating module, a data compression module, a self-adaptive optimization module and a data transmission control module;

The initialization configuration module is used for initializing and configuring radio frequency parameters of the LoRa communication equipment;

The mode switching module is used for initializing a state machine of the LoRa data transceiver and performing mode switching according to the event-triggered condition and the current state;

The data type list initializing module is used for initializing a data type list;

The data type list updating module is used for setting different service data types or carrying out correlation detection on the service data to obtain different service data types, and updating a data type list based on the different service data types;

The data compression module is used for selecting corresponding data compression algorithms to compress according to different service data types to obtain compressed data;

the self-adaptive optimization module is used for inputting compressed data to the LoRa data transceiver and transmitting the LoRa data based on RBAR rate self-adaptive optimization algorithm;

The data transmission control module is used for coordinating a sending end and a receiving end to select an optimal sending spread spectrum factor and a receiving window by sending an RTS message and receiving a CTS message based on an RTS/CTS mechanism, and completing the LoRa data transmission process.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) According to the invention, corresponding data compression algorithms are selected for compression according to different service data types, further, if the data type is judged to be the weak correlation data type, a CDCA-1 algorithm is adopted for data compression, if the data type is judged to be the strong correlation data type, a CDCA-2 algorithm is adopted for data compression, wherein the CDCA-1 algorithm is combined with extrapolation prediction and bit aggregation technology for data compression, the CDCA-2 algorithm is used for data compression by combining a run coding mode with differential coding, the corresponding data compression algorithm is selected for reducing the transmission data amount, improving the transmission rate, the compressed data is input to a LoRa data transceiver, loRa data transmission is carried out based on a RBAR rate self-adaptive optimization algorithm, and considerable lossless data compression of the transmission data can be realized, so that the time and resources required for transmission are reduced, the bandwidth utilization rate is greatly improved, and meanwhile, the energy required for transmission is correspondingly reduced under the condition that the data is required to be frequently transmitted, so that the battery life of equipment is prolonged.

(2) Based on an RTS/CTS mechanism, the invention coordinates the sending end and the receiving end to select the optimal sending spread spectrum factor and the receiving window by sending the RTS message and receiving the CTS message, so that the node can adaptively modify the spread spectrum factor according to the high channel quality, the transmission rate of the data packet is improved or reduced, and the throughput of the LoRa network is effectively improved under the condition of ensuring the reliable transmission of the data.

(3) The LoRa data transceiver is driven by a finite state machine, and performs mode switching according to the condition triggered by the event and the current state, so that efficient and stable LoRa data transceiving can be realized, the integrity and the accuracy of data are ensured, and the LoRa data transceiver has a large application value for deploying a large-scale sensor network or an Internet of things system.

(4) The LoRa data transceiver has strong portability, can adapt to different data types by simply modifying parameters, can be used on any hardware by only changing a control interface, can modify similar custom transmission parameters such as power, radio frequency factors, bandwidth and the like, and particularly depends on the use field Jing Ding such as whether the use field is open or not and the distance between the points, so that the LoRa data transceiver can be transplanted to the application of the Internet of things with different data types efficiently and conveniently and is used as the bottom communication support of the Internet of things equipment.

Drawings

FIG. 1 is a flow chart of a low rate adaptive optimized LoRa data receiving and transmitting control method of the present invention;

FIG. 2 is a schematic diagram of a LoRa state machine model of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

Example 1

As shown in fig. 1, this embodiment provides a low-rate adaptive optimization LoRa data transceiving control method, which performs initialization configuration on various parameters of a LoRa communication device, performs correlation detection or manual configuration on different service data types, adaptively selects a compression algorithm suitable for the data types, performs adaptive switching in a CDCA-1 algorithm and a CDCA-2 algorithm according to the different data types, then performs a LoRa data transmission process, performs a RBAR rate adaptive optimization algorithm in the transmission process, performs an RTS/CTS mechanism based on an RTS/CTS mechanism, and performs coordination by sending an RTS message and receiving a CTS message, so that a sending end and a receiving end can select an optimal sending SF and a receiving window to improve reliability and efficiency of data transmission and reduce occurrence of collision;

In this embodiment, a corresponding DATA compression algorithm is selected according to the DATA TYPE in the DATA TYPE list data_type, and a CDCA-1 algorithm is used if the DATA TYPE is the weak CORRELATION DATA low_correlation (CORRELATION DATA COPRESSION ALGORITHM-1), and a CDCA-2 algorithm is used if the DATA TYPE is the strong CORRELATION DATA high_correlation (CORRELATION DATA COPRESSION ALGORITHM-2); the CDCA-1 algorithm applies an improved static Huffman coding algorithm and combines extrapolation prediction and bit aggregation technology to realize data compression; the CDCA-2 algorithm provides better compression effect for data with stronger correlation by combining a difference value coding mode with a run-length coding mode;

In this embodiment, after the power-on of the LoRa communication device, basic initialization configuration is performed on radio frequency parameters, where main configuration parameters include a transmission frequency, a transmission power, a spreading factor, a coding rate, a bandwidth, a transmission timeout time, a reception timeout time, a frequency hopping parameter, and the like, and after the initialization configuration, the LoRa radio frequency module can be driven to transmit and receive data;

In this embodiment, the time data_correlation_configuration is preconfigured for the DATA type, and the LoRa communication device needs to acquire the CORRELATION of the specific service DATA type to be transmitted before the service DATA is transmitted, and sets the service DATA type as strong CORRELATION DATA high_correlation or weak CORRELATION DATA low_correlation;

The DATA compression algorithm may be manually configured or detected by the system within the time data_correlation_configuration to adaptively select the DATA compression algorithm.

In this embodiment, in the data transceiving process, because of the orthogonal relationship between different spread spectrum SFs, devices using different SFs are mutually isolated, the receiving SF of the receiving end and the transmitting SF of the transmitting end must be the same to successfully communicate, and the devices acquire channel quality and realize synchronization of the spread spectrum factors SF through two handshakes set by RBAR algorithm, and then transmit and receive data;

In this embodiment, after receiving all the valid data, the data is decoded and decompressed, so as to complete the transmission process of the LoRa data.

In this embodiment, the specific steps of the initialization procedure of the LoRa radio frequency parameter are:

a1: reading the version information of the radio frequency chip;

a2: initializing a register structure and a register pointer, and reading all local initialization values of the radio frequency chip;

a3: initializing a GPIO port corresponding to SPI communication of the SX1276 and resetting the SX1276;

a4: setting to a LoRa modem mode and turning on the LoRa modem;

A5: setting the current chip working mode to be idle;

a6: setting an LNA gain mode;

a7: setting the center frequency of data transmission, wherein the allowable frequency setting range is 433Mhz-928Mhz, and preferably 435M;

A8: setting the spreading factor of data transmission and reception, wherein the spreading factor allows setting the range to be 6-12, preferably 9, and the corresponding chip/symbol value to be 64-4096;

A9: setting the error correcting code length of data transmission and acceptance, determining the size of the coding rate, allowing the setting range to be 1-4, preferably 1, and the corresponding cyclic coding rate to be 4/5-4/8;

a10: setting the bandwidth size of data transmission and reception, wherein the bandwidth allowable setting range is 7.8kHz-500kHz;

A11: setting a CRC check mode, and selecting whether CRC check is performed or not;

A12: setting a header mode, an explicit header mode and an implicit header mode may be selected;

A13: selecting a PA output pin, wherein RFO can be selected as the output pin, the maximum power is 14dBm, or PA_BOOST can be selected as the output pin, and the maximum power is 20dBm;

a14: setting the working mode of the chip as a standby mode after the parameter setting is completed;

The spreading factor is set to determine the transmission rate, and the LoRa uses a plurality of information chips to represent the effective data load, i.e., one information bit needs a plurality of symbols to be transmitted, and the number of the required symbols is the spreading factor. The spreading factor may also be defined as the ratio between the chip rate and the sending rate Rs of the spread information, with specific preferred values being given in the table below.

Spread spectrum factor value range table

To enhance the robustness of the wireless communication link, the LoRa performs forward error detection and error correction at the physical layer, i.e., using a cyclic error correction coding technique, the coding rate being the ratio between the number of valid data bits and the number of data bits actually to be transmitted, and the different coding rates may generate how much different transmission overhead, the coding rates are typically specified between device nodes or placed in header information for transmission, with the chip selectable coding rates and corresponding overhead ratios being listed in the table below.

Coding rate range table

Setting the signal bandwidth of the LoRa, which increases the signal bandwidth, shortens the transmission time but decreases the reception sensitivity, requires setting a suitable value, and the signal bandwidth is selectable as shown in the table below.

LORA bandwidth value range table

Depending on the selected mode of operation, two types of headers may be selected. On RegModemConfig1 registers, the header type is selected by setting ImplicitHeaderModeOn bits. The explicit header mode is the default mode of operation. In this mode, the header contains information about the payload, including: a payload length in bytes; forward error correction code rate; whether an optional 16-bit payload CRC is open. The header is sent according to a maximum error correction code (4/8). In addition, the header also contains its own CRC, so that the receiver can discard invalid headers. In certain cases, if the payload length, coding rate, and CRC are fixed or known, it is more efficient to shorten the transmission time by invoking an implicit header mode. In this case, it is necessary to manually set the payload length, the error coding rate, and the CRC at both ends of the wireless link. Note that: if the spreading factor SF is set to 6, only the implicit header mode can be used.

As shown in fig. 2, the LoRa data transceiver is driven by a finite state machine, and performs mode switching according to an event-triggered condition and a current state, so as to realize seamless switching and flexible control of the LoRa device between different operation modes, and the specific steps are as follows:

B1: the state machine starts from an initial state, typically a standby (Idle) mode.

B2: when a Receive event is triggered, such as receipt of a data packet by another device or a Receive timer times out, the state machine will switch to a Receive (Receive) mode. In the receiving mode, the driver firstly executes signal detection, carries out signal demodulation on useful signals after detecting the signals, and carries out data decoding after demodulating useful data streams to obtain final data packets;

b3: when a Transmit event is triggered, such as an application indicating that a packet is to be transmitted or a Transmit timer times out, the state machine will switch to Transmit (Transmit) mode. In a transmission mode, a driver firstly executes channel coding of a data packet to be transmitted, then carries out data modulation on the coded binary stream, and finally executes physical layer transmission operation and transmits the physical layer transmission operation from an antenna;

b4: when channel activity Detection needs to be performed, the state machine will switch to CAD (CHANNEL ACTIVITY Detection) mode. In CAD mode, the driver listens to the channel and detects if other devices are transmitting data.

B5: when the sending or receiving operation is completed, the state machine can make corresponding decisions according to the application requirements. For example, the module is initialized in the standby mode, then periodically wakes up the module to execute CAD mode for signal detection, then processes if useful data is available after detecting the channel, and enters the sleep mode if not, thereby reducing the power consumption to the greatest extent, and then can switch back to the standby mode to save energy, or reenter the receiving mode to wait for further data.

B6: when it is desired to enter a low power state, the state machine will switch to Sleep (Sleep) mode. In sleep mode, the driver may start a timer to wake up the device after a specified time or wake up the device based on an external trigger event.

In this embodiment, after receiving the data transmission instruction, the device enters a transmission mode RFLR _state_tx_init from a standby mode RFLR _state_idle, and performs related operations, which specifically includes the steps of:

s1, checking whether a frequency hopping function is started in LoRa setting;

s2, setting a TX_DONE transmission completion flag interrupt flag mask to capture a transmission completion event;

s3, setting a data load payload length REG_LR_ PAYLOADLENGTH;

s4, setting a transmission direction REG_LR_ FIFOTXBASEADDR of a data buffer FIFO;

S5, setting a data buffer area FIFO address pointer REG_LR_ FIFOADDRPTR;

s6, writing the payload buffer of the data load buffer into a LoRa module, and setting a LoRa mode of the SX1276 module as a transmission mode;

S7, switching the mode to a transmission execution mode RFLR _STATE_TX_RUNNING, and circularly detecting an interrupt register;

And S8, switching to a transmission completion mode RFLR _STATE_TX_DONE if the transmission completion flag of the TX_DONE is detected, and returning to transmission failure if the transmission completion interrupt flag is still not detected after timeout.

In this embodiment, after receiving the received data command, the device enters a reception initialization mode RFLR _state_rx_init from a standby mode RFLR _state_idle, and performs related operations, which specifically includes the following steps:

s1: setting an RX_DONE reception completion interrupt flag mask to capture reception events while clearing a previous interrupt flag;

S2: checking whether a frequency hopping function is started in LoRa setting;

s3: setting the LoRa to a single reception if the RX single mode is enabled in the LoRa setting, otherwise, setting the LoRa to a cyclic reception mode;

S4: setting a received data BUFFER address, setting a data BUFFER FIFO address pointer as an Rx base address, and writing the data BUFFER FIFO address pointer into a register;

s5: clearing a received data buffer area and starting a receiving timeout timer;

S6: switching the mode to a reception execution mode RFLR _state_rx_running, and looping the detection interrupt register;

S7: clearing the receiving completion interrupt flag and switching the mode to a receiving completion mode RFLR _state_rx_done when the receiving completion flag bit of rx_done is detected, and updating a receiving timeout timer;

S8: performing CRC (cyclic redundancy check) on the received data in RFLR _STATE_RX_DONE mode, if the CRC is successful, writing the received data into a receiving BUFFER area, and returning a receiving completion result;

s9: if the mode is RX single-time receiving mode, detecting whether the receiving time is overtime, if the receiving time is overtime, switching the mode to a receiving time-out mode RFLR _STATE_RX_TIMEOUT and returning a receiving time-out result.

In this embodiment, after receiving the channel monitoring command, the device enters the CAD monitoring mode RFLR _state_cad_init from the standby mode RFLR _state_idle, and performs related operations, which specifically includes the steps of:

s1: setting a CAD_DONE monitoring completion mark interrupt mark mask to capture a CAD monitoring completion event;

S2: setting a working mode to RFLR _STATE_CAD_RUNNING, and circularly detecting an interrupt register;

S3: and judging the current CHANNEL state after detecting that the CAD monitoring is finished, if the RF_channel_ACTIVITY_DETECTED represents that the current CHANNEL is active, switching the working mode to the receiving mode to execute data receiving, and if the RF_channel_EMPTY represents that the current CHANNEL is idle, returning a CHANNEL idle result.

In this embodiment, the CDCA algorithm is applied to compress the sensor data and transmit two uncompressed sensor acquisition value values, such as an air temperature sensor and an air humidity sensor, each value encoded as 16 bits, for a total of 2 bytes, which the node will send 4 bytes. If Huffman algorithm and extrapolation prediction are used, the temperature value may be encoded as 3 bits and the humidity value may be encoded as 3 bits, resulting in a 2 byte transmission. Furthermore, if a bit aggregation technique is used, it will only produce 8 bits, so only 1 byte should be transmitted.

In this embodiment, the LoRa data transceiver implements a simple physical layer interface for post-migration call, and specifically includes:

LoRa initializing a function;

2. a data packing function;

3.A data packet transfer function;

4. a data packet transmission function;

5. Receiving a data function;

6. A channel detection function;

7. the receiver currently receives a status function;

8. a receiver current data processing state function;

9. the radio frequency module starts a function;

10. the radio frequency module closes the function;

11. acquiring a parameter value of a radio frequency module and an expansion function of an object;

in this embodiment, the service data type configuration flow specifically includes the steps of:

The LoRa communication equipment needs to acquire the CORRELATION of specific service DATA types to be transmitted before service DATA transmission, and sets the service DATA types to be high_correlation or low_correlation types, so that the configuration can be performed manually or the system can detect the service DATA in a DATA_correlation_configuration time period, and then a DATA compression algorithm can be selected adaptively;

C1: initializing a DATA TYPE list DATA_TYPE, which comprises DATA TYPE names and DATA CORRELATION characteristics, dividing the DATA TYPE list into two TYPEs of high_CORRELLATION or low_CORRELLATION, and determining which DATA compression algorithm is used by different TYPEs;

C2: firstly, searching a serial number in a DATA TYPE list DATA_TYPE according to a DATA TYPE name, and then artificially configuring the service DATA TYPE as high_CORRELLATION or low_CORRELLATION according to experience;

And C3: for the service DATA type without artificial configuration, the system detects in the data_correlation_config time period according to the input DATA, and the detection method is as follows: n DATA are read in one by one according to a CORRELATION threshold value correlation_GATE preset in an actual scene, and each time new DATA which is different from the previous DATA are read in, the effective DATA quantity M is increased by one, the size relation between the final M/N and the correlation_GATE is judged, and a DATA_TYPE list is written;

in this embodiment, the system will execute a data compression algorithm according to the correlation of service data types, and the specific steps are:

D1: selecting a corresponding DATA compression algorithm according to the DATA TYPE in the DATA TYPE list DATA_TYPE, using CDCA-1 (CORRELATION DATA COPRESSION ALGORITHM-1) if the DATA TYPE is LOW_CORRELATION, and using CDCA-2 (CORRELATION DATA COPRESSION ALGORITHM-2) if the DATA TYPE is HIGH_CORRELATION;

d2: the CDCA-1 data compression algorithm comprises the following specific steps:

d21: firstly, reading and reserving symbols, and then converting the values into decimal values based on positive numbers;

D22: multiplying by a sufficiently large power of 10, converting the positive-number-based decimal values to positive-number-based integer values, and converting these integer values to a digital-based binary representation;

D23: the complete value of the first measurement data of each round of transmission will be reserved, and this complete value is used as the starting point of the transmission task of the round.

D24: starting from the second value, an improved static huffman coding algorithm is applied, which comprises the following specific steps:

d24 (1): the data is first predicted using an extrapolation prediction algorithm to further reduce the number of bits of the data. An extrapolation prediction algorithm is a prediction method based on historical data that uses known data points to predict unknown data points. The difference between two data to be transmitted can be reduced by using extrapolation prediction, and the specific prediction method is as follows: the first three values remain unchanged, and from the 4 th value, an extrapolation predicted value is obtained through V _i＝5/4V_i-1+1/2V_i-2-3/4V_i-3;

D24 (2): the difference value of the second value and the third value is directly subjected to XOR operation with the previous value to obtain a difference value, and the difference value of the two values is obtained by performing XOR operation on the real value and the extrapolated predicted value to perform binary data comparison from the fourth value; the sequence of differences is encoded using the Huffman algorithm to reduce the number of bits of data. Huffman coding is a probability-based coding method, which uses shorter codes to represent symbols with higher occurrence frequency, uses longer codes to represent symbols with lower occurrence frequency, and the Huffman coding results are shown in the following table, and the coding results are cascade connection of the bit number s _i of the difference value and the binary representation of the difference value;

n_i	s_i	di
			0	00	0
1	01	-1,+1
			2	100	-3,-2,2,3
3	101	-7,……,-4,4,……,7
			4	110	-15,……,-8,8,……,15
5	1110	-31,……,-16,16,……,31
			6	11110	-63,……,-32,32,……,63
7	111110	-127,……,-64,64,……,127
			8	1111110	-255,……,-128,128,……,255

D24 (3): the data is aggregated using a bit aggregation technique to further reduce the number of bits of the data. Bit aggregation techniques are a method of combining multiple data bits into one larger data bit. Firstly dividing data to be transmitted into blocks according to bytes, circularly moving a data sequence to the leftmost side, and then carrying out bit aggregation among bytes to eliminate redundant parts of different bytes;

D3: the CDCA-2 data compression algorithm is modified by introducing a run-length coding method for the data types with very strong correlation on the basis of the CDCA-1 data compression algorithm, and the CDCA-2 data compression algorithm comprises the following specific steps:

d31: firstly, reading and reserving symbols, and then converting the values into decimal values based on positive numbers;

D32: multiplying by a sufficiently large power of 10, converting the positive-number-based decimal values to positive-number-based integer values, and converting these integer values to a digital-based binary representation;

D33: the complete value of the first measurement data of each round of transmission will be reserved, and this complete value is used as the starting point of the transmission task of the round.

D34: starting from the second value, directly applying an XOR operation to compare binary data, and obtaining a difference value of the two values;

D35: if any consecutive value appears to be "0", CDCA-2 will only send an instance of the previous value and the number of repetitions.

D36: the data is aggregated using a bit aggregation technique to further reduce the number of bits of the data.

In this embodiment, a rate adaptive mechanism based on RBAR algorithm is used between the LoRa communication nodes to synchronize the optimal spreading factor SF, and based on the RTS/CTS mechanism, by sending an RTS message and receiving a CTS message, the sending end and the receiving end can coordinate and select the optimal sending SF and receiving window, so as to improve the reliability and efficiency of data transmission and reduce the occurrence of collision, and the specific steps are as follows:

e1: before sending the data packet, the sending end firstly sends a request to send RTS message to the receiving end.

E2: after receiving the RTS message, the receiving end obtains the signal-to-noise ratio (SNR) of the channel and determines the optimal transmission spread Spectrum Factor (SF) of the transmitting end according to a preset demodulation SNR threshold.

Different SF parameters correspond to different data rates, the larger the SF is, the smaller the data rate is, but the lower the demodulation signal-to-noise ratio threshold is, the stronger the anti-interference capability is, the demodulation signal-to-noise ratio threshold is that the signal-to-noise ratio of the LoRa data receiving and transmitting data packet under the SF parameter configuration is larger than that of the LoRa data receiving and transmitting data packet and can be correctly demodulated, so that the closest demodulation signal-to-noise ratio is selected according to the signal-to-noise ratio of the received data packet, and therefore, the SF parameter setting is corresponding, and the rate maximization is achieved on the basis of demodulation;

the optimal SF spreading factor and demodulation SNR threshold are shown in the following table:

SF	data rate/kbps	Transmission time/ms	Demodulation signal-to-noise threshold/dB
				6	9.375	24	-5.0
7	5.468	40	-7.5
				8	3.125	80	-10.0
9	1.757	140	-12.0
				10	0.976	280	-15.0
11	0.537	561	-17.5
				12	0.293	1122	-20.0

From the above, it can be seen that the spreading factor affects the distance and transmission rate of data transmission, so selecting the optimal SF can improve communication quality and efficiency.

E3: the receiving end adds the optimal sending SF to a clear-to-send (CTS) message and sends the message to the sending end; meanwhile, the receiving end enters a section of specific receiving window according to the optimal SF, and the window is used for receiving the data packet. In the receiving window, the receiving end may attempt to successfully receive the data packet, or wait for the receiving window to recover the default SF receiving state after finishing.

E4: the transmitting end extracts the best transmitted SF information in the CTS message and uses the SF to transmit the data packet to the receiving end. After the transmission is completed, the transmitting end resumes the default SF setting. Meanwhile, after receiving the CTS message, other nodes enter a silence window, i.e. do not send the message for a period of time, so as to avoid collision.

The SF is a radio frequency parameter, i.e. spreading factor, of the LoRa data transmission and reception, and the use of the SF to transmit the data packet to the receiving end is to configure the spreading factor SF of the LoRa data transmission and reception to this value for data transmission.

Example 2

This embodiment is the same as embodiment 1 except for the following technical matters;

The embodiment provides a low-rate adaptive optimized LoRa data transceiver control system, which comprises: the system comprises an initialization configuration module, a mode switching module, a data type list initialization module, a data type list updating module, a data compression module, a self-adaptive optimization module and a data transmission control module;

in this embodiment, the initialization configuration module is configured to perform initialization configuration on radio frequency parameters of the LoRa communication device;

In this embodiment, the mode switching module is configured to initialize a state machine of the LoRa data transceiver, and perform mode switching according to an event-triggered condition and a current state;

in this embodiment, the data type list initializing module is configured to initialize a data type list;

in this embodiment, the data type list updating module is configured to set different service data types, or perform correlation detection on service data to obtain different service data types, and update the data type list based on the different service data types;

in this embodiment, the data compression module is configured to select a corresponding data compression algorithm according to different service data types to compress the data, so as to obtain compressed data;

In this embodiment, the adaptive optimization module is configured to input the compressed data to the LoRa data transceiver, and perform LoRa data transmission based on a RBAR rate adaptive optimization algorithm;

In this embodiment, the data transmission control module is configured to coordinate, based on an RTS/CTS mechanism, a sending end and a receiving end to select an optimal sending spreading factor and a receiving window by sending an RTS message and receiving a CTS message, thereby completing a LoRa data transmission process.

The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.

Claims

1. The low-rate self-adaptive optimized LoRa data receiving and transmitting control method is characterized by comprising the following steps of:

initializing a data type list;

2. The low-rate adaptive optimization LoRa data transceiving control method according to claim 1, wherein the initializing configuration of radio frequency parameters of the LoRa communication device specifically comprises: initializing a register structure and a register pointer, acquiring all initialization values of radio frequency parameters, setting the center frequency of data transmission, setting the spread spectrum factors of data transmission and reception, setting the error correction code length of data transmission and reception, setting the bandwidth size of data transmission and reception, setting a CRC (cyclic redundancy check) mode and setting a header mode.

3. The low-rate adaptive optimized LoRa data transceiving control method according to claim 1, wherein the data types comprise a weak correlation data type and a strong correlation data type, a CDCA-1 algorithm is adopted for data compression if the data type is determined to be the weak correlation data type, a CDCA-2 algorithm is adopted for data compression if the data type is determined to be the strong correlation data type, the CDCA-1 algorithm is combined with extrapolation prediction and a bit aggregation technology for data compression, and the CDCA-2 algorithm is combined with a run-length coding mode for data compression by using differential coding.

4. The low-rate adaptive optimized LoRa data transceiver control method as claimed in claim 3, wherein the data compression is performed by adopting a CDCA-1 algorithm, and the specific steps include:

encoding the difference sequence using a Huffman algorithm;

5. The low-rate adaptive optimized LoRa data transceiver control method as claimed in claim 3, wherein the data compression is performed by adopting a CDCA-2 algorithm, and the specific steps include:

6. The low-rate adaptive optimized LoRa data transceiver control method as claimed in claim 1, wherein the LoRa data transceiver is driven by a finite state machine, and the mode switching is performed according to an event-triggered condition and a current state, specifically comprising:

7. The method for controlling low-rate adaptive optimization of LoRa data transceiving according to claim 6, wherein switching to a reception mode when it is determined that a reception event is triggered comprises:

Checking whether a frequency hopping function is started in LoRa setting;

Clearing a received data buffer area and starting a receiving timeout timer;

Checking whether a frequency hopping function is started in LoRa setting;

Setting the data load length;

Setting the transmission direction of a data buffer area;

setting an address pointer of a data buffer area;

8. The low-rate adaptive optimized LoRa data transceiver control method of claim 1, wherein the method for detecting correlation of service data comprises:

9. The low-rate adaptive optimization LoRa data receiving and transmitting control method according to claim 1, wherein the coordination transmitting end and the receiving end select the optimal transmission spreading factor and the receiving window, and the completed LoRa data transmission process specifically comprises:

10. A low rate, adaptively optimized, loRa data transceiver control system, comprising: the system comprises an initialization configuration module, a mode switching module, a data type list initialization module, a data type list updating module, a data compression module, a self-adaptive optimization module and a data transmission control module;