Ultra-short range bluetooth communication system and method for underwater devices

Abstract

The application relates to the field of Bluetooth communication technology and provides an ultra-short-distance Bluetooth communication system and method for underwater equipment, which comprises the following steps: step 1, data packet construction: sensor data or control instructions to be transmitted, which are collected or calculated by a vital sign monitoring module, are packaged into short frame data packets of a preset format; step 2, forward error correction coding: forward error correction coding is applied to the completed short frame data packets to generate redundant check information, and the redundant check information is attached to the data packets to form error code resistance enhanced data packets; and step 3, high-strength radio frequency transmission: the working parameters of a Bluetooth radio frequency unit are configured, the transmission power of the Bluetooth radio frequency unit is set to the maximum allowable value supported by a chip, and the physical layer mode of the Bluetooth radio frequency unit is set to a coding physical layer mode with high processing gain; the anti-error code enhanced data packets are directionally transmitted to a slave device in an underwater environment under the configuration; and the application can preferably perform ultra-short-distance Bluetooth communication.

Description

Technical Field

[0001] This invention relates to the field of Bluetooth communication technology, and more specifically, to an ultra-short-range Bluetooth communication system and method for underwater equipment. Background Technology

[0002] Bluetooth technology, as a mature short-range wireless communication technology, is widely used in various land-based electronic devices. However, its 2.4GHz ISM band signal experiences extremely severe attenuation in underwater environments. Water, as a medium with a high dielectric constant, has a strong absorption effect on high-frequency radio frequency signals, resulting in the effective transmission distance of traditional Bluetooth signals in freshwater being only on the order of centimeters, and severe signal distortion, making reliable communication impossible.

[0003] Currently, underwater communication mainly relies on underwater acoustic communication or dedicated underwater electromagnetic wave communication modules. While underwater acoustic communication offers long transmission distances, it suffers from high latency, limited bandwidth, susceptibility to multipath effects and environmental noise interference, large device size, and high power consumption. Dedicated underwater electromagnetic wave communication modules, on the other hand, are typically expensive and incompatible with the vast Bluetooth device ecosystem on land.

[0004] In specific applications such as diving, there is an urgent need for data exchange at extremely close range (e.g., between devices worn by the same diver or between adjacent divers). For example, a diver's wrist-worn vital signs monitoring module needs to transmit heart rate, blood oxygen, and decompression data in real time to an underwater acoustic communication relay host worn on the torso. In this scenario, the distance between the communicating parties is fixed and very close (usually within 20 centimeters). Developing a low-cost, low-power underwater communication solution for these devices that is partially compatible with the existing Bluetooth technology ecosystem would have significant application value.

[0005] Therefore, there is an urgent need for a communication method that can overcome the inherent defects of Bluetooth technology in underwater applications and achieve stable and reliable data transmission in the very near field range. Summary of the Invention

[0006] The present invention provides an ultra-short-range Bluetooth communication system and method for underwater equipment, which can overcome some or all the defects of the prior art.

[0007] According to the present invention, an ultra-short-range Bluetooth communication method for underwater equipment is characterized in that the method is applied to a communication system including a master device and a slave device, wherein the master device is an underwater vital signs monitoring module, and the slave device is an underwater relay terminal or a teammate device, and the method includes the following on the master device side: Step 1, Data Packet Construction: The sensor data or control commands to be transmitted, which are collected or calculated by the vital signs monitoring module, are packaged into a short frame data packet of a preset format; wherein, the sensor data includes one or more of heart rate, blood oxygen saturation, respiratory rate, water depth, temperature and decompression plan information, and the control commands include alarm commands; Step 2, Forward Error Correction Coding: Forward error correction coding is applied to the constructed short frame data packet to generate redundant verification information, and the redundant verification information is appended to the data packet to form an error-resistant enhanced data packet; Step 3, High-intensity radio frequency emission: Configure the operating parameters of the Bluetooth radio frequency unit, set its transmit power to the maximum allowable value supported by the chip, and set its physical layer mode to a coded physical layer mode with high processing gain; with this configuration, the error-resistant enhanced data packet is transmitted to the slave device in an underwater environment. The stable wireless communication link between the master device and the slave device is established and maintained in the underwater near-field range, and its maximum reliable communication distance does not exceed 20 centimeters.

[0008] Preferably, in the data packet construction step, the short frame data packet uses ASCII character encoding to ensure protocol simplicity, and its frame structure includes the following in sequence: A fixed header of one byte, with a value of 0xFF; A one-byte command word used to identify the data type; A two-byte data length field is used to indicate the number of bytes of subsequent payload data; A variable-length payload data field is used to carry the sensor data or control commands; A one-byte check bit, the value of which is the result of a byte-by-byte XOR operation on all bytes from the command word to the last byte of the payload data field; A fixed terminator for a single byte, with a value of 0x0D.

[0009] Preferably, in the high-intensity radio frequency transmission step, the coded physical layer mode specifically refers to the Coded PHY mode defined by Bluetooth 5.0 and above standards. It adopts an S=8 encoding scheme and uses a symbol repetition mechanism to improve the received signal-to-noise ratio in order to combat the severe signal attenuation caused by the underwater environment.

[0010] Preferably, a link layer optimization step is included before the high-intensity radio frequency transmission step: a) Configure the Bluetooth connection interval to an extremely short value in the range of 3 to 20 milliseconds to increase the handshake opportunities per unit time and achieve fast retransmission; b) In each successful connection event, enable and utilize the maximum link layer packet length allowed by the Bluetooth protocol for data transmission to compensate for the decrease in effective throughput caused by high retransmission rates.

[0011] Preferably, the method further includes an adaptive power control step: A) Receive channel quality feedback information from the slave device, including an indication of received signal strength; B) Based on the value of the received signal strength indication, dynamically adjust the local transmit power between the maximum allowable transmit power and a lower power level; when the signal quality is good, moderately reduce the power to save energy, and when the signal quality deteriorates, immediately restore to the maximum power to maintain link stability.

[0012] This invention provides an ultra-short-range Bluetooth communication system for underwater equipment, including a master device and a slave device, both of which are sealed in a watertight structure capable of withstanding hydrostatic pressure at least 30 meters underwater; The main equipment is an underwater vital signs monitoring device used for operation. The slave device is configured as follows: Set the receiver sensitivity of its Bluetooth radio frequency unit to the highest level and continuously monitor the communication channel; The radio frequency signal from the master device is captured, demodulated and decoded, and the redundant verification information generated in the forward error correction coding step is used to automatically detect and correct bit errors generated during transmission. After successfully receiving and correctly decoding the data packet, a link layer acknowledgment signal and optional channel quality feedback including a received signal strength indication are sent to the master device.

[0013] Preferably, the Bluetooth system-on-a-chip configured in the master and slave devices is the nRF5340; wherein, The application processor core of the nRF5340 is configured to perform data packaging, forward error correction coding, application layer protocol parsing, and the adaptive power control algorithm. The network processor core of the nRF5340 is configured to run the Bluetooth link layer protocol stack and process physical layer radio frequency timing, connection event scheduling, and the transmission and reception of the link layer acknowledgment signals in hard real-time.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention, through a series of extreme hardware and software co-optimizations, successfully expands the application scenarios of Bluetooth communication to the underwater near-field range, solving the problem of short-range interconnection in specific scenarios.

[0015] This invention employs multiple technologies, including Coded PHY, forward error correction, extremely short connection intervals and maximum packet length, and dual-core chips to ensure radio frequency timing, to construct a powerful anti-error and fast recovery mechanism, effectively combating severe signal attenuation and interference underwater.

[0016] Although maximum power transmission is used in the short term, this invention, through dynamic power control, a simplified protocol and data packet design, and the low-power characteristics of the chip itself, minimizes overall system power consumption while ensuring communication quality. The method's high efficiency reduces radio on-time, further saving power.

[0017] This invention is based on a general-purpose commercial Bluetooth chip (such as nRF5340), eliminating the need for customized special RF front-ends or protocol chips, which greatly reduces hardware costs and development difficulty, and is conducive to its promotion in consumer and industrial underwater devices.

[0018] This invention supports the feedback of ACK and RSSI information from the device to the master device, which not only achieves reliable transmission, but also provides a basis for dynamic optimization and health status monitoring of the link. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an ultra-short-range Bluetooth communication method for underwater equipment in an embodiment. Detailed Implementation

[0020] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings and embodiments. It should be understood that the embodiments are merely illustrative and not limiting of the invention. Example

[0021] like Figure 1 As shown, this embodiment provides an ultra-short-range Bluetooth communication method for underwater equipment. The method is applied to a communication system including a master device and a slave device. The master device is an underwater vital signs monitoring module, and the slave device is an underwater relay terminal or a teammate device. The method includes the following on the master device side: Step 1, Data Packet Construction: The sensor data or control commands to be transmitted, which are collected or calculated by the vital signs monitoring module, are packaged into a short frame data packet of a preset format; wherein, the sensor data includes one or more of heart rate, blood oxygen saturation, respiratory rate, water depth, temperature and decompression plan information, and the control commands include alarm commands; Step 2, Forward Error Correction (FEC) Coding: Forward error correction coding is applied to the constructed short frame data packet to generate redundant verification information, and the redundant verification information is appended to the data packet to form an error-resistant enhanced data packet; After the application layer data is packaged, an additional layer of forward error correction (FEC) code, such as Reed-Solomon code or convolutional code, is added before transmission. The receiving end can use FEC information to automatically detect and correct a certain number of bit errors, thereby avoiding the retransmission of the entire data packet and significantly improving the communication success rate.

[0022] Step 3, High-intensity radio frequency emission: Configure the operating parameters of the Bluetooth radio frequency unit, set its transmit power to the maximum allowable value supported by the chip, and set its physical layer mode to a coded physical layer mode with high processing gain; with this configuration, the error-resistant enhanced data packet is transmitted to the slave device in an underwater environment. The stable wireless communication link between the master device and the slave device is established and maintained in the underwater near-field range, and its maximum reliable communication distance does not exceed 20 centimeters.

[0023] In this embodiment, during the data packet construction step, the short frame data packet uses ASCII character encoding to ensure protocol simplicity, and its frame structure includes the following in sequence: A fixed header of one byte, with a value of 0xFF; A one-byte command word used to identify the data type; A two-byte data length field is used to indicate the number of bytes of subsequent payload data; A variable-length payload data field is used to carry the sensor data or control commands; A one-byte check bit, the value of which is the result of a byte-by-byte XOR operation on all bytes from the command word to the last byte of the payload data field; A fixed terminator for a single byte, with a value of 0x0D. See Table 1 for details. Table 1 Basic Data Packet Format Fields byte count illustrate Baotou 1 Fixed value 0xFF command word 1 Command words (0x00-0xFF) Data length 2 Length of subsequent data fields data N Payload data (N=0-65535) Check bit 1 XOR check (from CMD to the last byte of the data field) End symbol 1 Fixed value 0x0D Complete data example: FF 01 00 1B 3C 3C 3C 0E42 07 D0 00 01 8B CD 0FA0 10 68 93 20 F0 00 1415 00 14 00 14 00 14 60 0D Check digit calculation: uint8_t check(uint8_t cmd, uint8_t* data, uint16_t length) { / / Calculate the check digits (from the command word to the last byte of the data field). uint8_t checksum = cmd; / / Start from the command word for (uint16_t i = 0; i <length; i++) { checksum ^= data[i]; } return checksum; } Sample code: void generate_diving_packet() { / / 1. Packet header and command word uint8_t packet

[32] = {0xFF, 0x01}; / / Packet header (0xFF) + command word (0x01) / / 2. Data length (0x001B = 27 bytes) packet[2] = 0x00; packet[3] = 0x1B; / / 3. Data fields (filled in field order) / / Heart rate (60) -> 0x3C packet[4] = 0x3C; / / Blood oxygen (60) -> 0x3C packet[5] = 0x3C; / / Respiratory rate (60) -> 0x3C packet[6] = 0x3C; / / Body temperature (36.5*100=3650) ->0x0E 0x42 packet[7] = 0x0E; packet[8] = 0x42; / / Ambient temperature (20*100=2000) -> 0x07 0xD0 packet[9] = 0x07; packet

[10] = 0xD0; / / Atmospheric pressure (101325Pa) -> 0x00 0x01 0x8B 0xCD packet

[11] = 0x00; packet

[12] = 0x01; packet

[13] = 0x8B; packet

[14] = 0xCD; / / Water depth (4000cm) -> 0x0F 0xA0 packet

[15] = 0x0F; packet

[16] = 0xA0; / / Battery level (16%) -> 0x10 packet

[17] = 0x10; / / Timestamp (1754472688) -> 0x68 0x93 0x20 0xF0 packet

[18] = 0x68; packet

[19] = 0x93; packet

[20] = 0x20; packet

[21] = 0xF0; / / Arrival time at the first stop (20 minutes) -> 0x00 0x14 packet

[22] = 0x00; packet

[23] = 0x14; / / First stop depth (21 meters) -> 0x15 packet

[24] = 0x15; / / First stop stop time (20 minutes) -> 0x00 0x14 packet

[25] = 0x00; packet

[26] = 0x14; / / Total dive time (20 minutes) -> 0x00 0x14 packet

[27] = 0x00; packet

[28] = 0x14; / / Total decompression time (20 minutes) -> 0x00 0x14 packet

[29] = 0x00; packet

[30] = 0x14; / / 4. Calculate the parity bit (XOR from the command word to the last byte of the data field) uint8_t checksum = packet[1]; / / Starting from the command word for (int i = 4; i<= 30; i++) { checksum ^= packet[i]; } packet

[31] = checksum; / / 5. End symbol packet

[32] = 0x0D; / / Print the complete generated data packet printf("Generated packet (hex):\n"); for (int i = 0; i<33; i++) { printf("%02X ", packet[i]); if ((i + 1) % 8 == 0) printf("\n"); } printf("\n\n"); / / Print field parsing printf("Field Breakdown:\n"); printf("Header: 0x%02X\n", packet[0]); printf("Command: 0x%02X (Upload Data)\n", packet[1]); printf("Data Length: %d bytes\n", (packet[2]<<8) | packet[3]); printf("Heart Rate: %d bpm\n", packet[4]); printf("SpO2: %d%%\n", packet[5]); printf("Respiration Rate: %d bpm\n", packet[6]); printf("Body Temp: %.1f C\n", ((packet[7]<<8) | packet[8]) / 100.0); printf("Env Temp: %.1f C\n", ((packet[9]<<8) | packet

[10] ) / 100.0); printf("Pressure: %d Pa\n", (packet

[11] <<24) | (packet

[12] <<16) |(packet

[13] <<8) | packet

[14] ); printf("Water Depth: %d cm\n", (packet

[15] <<8) | packet

[16] ); printf("Battery: %d%%\n", packet

[17] ); printf("Timestamp: %u\n", (packet

[18] <<24) | (packet

[19] <<16) |(packet

[20] <<8) | packet

[21] ); printf("First Stop Arrival: %d min\n", (packet

[22] <<8) | packet

[23] ); printf("First Stop Depth: %dm\n", packet

[24] ); printf("First Stop Duration: %d min\n", (packet

[25] <<8) | packet

[26] ); printf("Total Dive Time: %d min\n", (packet

[27] <<8) | packet

[28] ); printf("Total Decomp Time: %d min\n", (packet

[29] <<8) | packet

[30] ); printf("Checksum: 0x%02X\n", packet

[31] ); printf("Footer: 0x%02X\n", packet

[32] ); In this embodiment, the coded physical layer mode in the high-intensity radio frequency transmission step specifically refers to the Coded PHY mode defined by Bluetooth 5.0 and above standards. It adopts an S=8 encoding scheme and uses a symbol repetition mechanism to improve the received signal-to-noise ratio in order to combat the severe signal attenuation caused by the underwater environment.

[0024] Abandon high-speed, low-fault-tolerance PHYs (such as 2Mbps) and choose the most robust 1M PHY or Coded PHY (S=8). Coded PHYs use repeated encoding to trade time for gain, which can greatly improve the signal-to-noise ratio (SNR) at the receiver, making them very suitable for such extremely low SNR environments, although the data throughput will be significantly reduced.

[0025] In this embodiment, a link layer optimization step is included before the high-intensity radio frequency transmission step: a) Configure the Bluetooth connection interval to an extremely short value in the range of 3 to 20 milliseconds to increase the handshake opportunities per unit time and achieve fast retransmission; b) In each successful connection event, enable and utilize the maximum link layer packet length allowed by the Bluetooth protocol for data transmission to compensate for the decrease in effective throughput caused by high retransmission rates.

[0026] In this embodiment, the method further includes an adaptive power control step: A) Receive channel quality feedback information from the slave device, including an indication of received signal strength; B) Based on the value of the received signal strength indication, dynamically adjust the local transmit power between the maximum allowable transmit power and a lower power level; when the signal quality is good, moderately reduce the power to save energy, and when the signal quality deteriorates, immediately restore to the maximum power to maintain link stability.

[0027] This embodiment provides an ultra-short-range Bluetooth communication system for underwater equipment, including a master device and a slave device, both of which are sealed in a watertight structure capable of withstanding hydrostatic pressure of at least 30 meters underwater. The main device is an underwater life sign monitoring device for operation; it packages sensor data (decompression plan, alarm) and attaches an FEC checksum.

[0028] The network core transmits data packets at maximum power in Coded PHY mode via the radio frequency front end. The network core listens for acknowledgment (ACK) signals from slave devices.

[0029] The slave device is configured as follows: Set the receiver sensitivity of its Bluetooth radio frequency unit to the highest level and continuously monitor the communication channel; The radio frequency signal from the master device is captured, demodulated and decoded, and the redundant verification information generated in the forward error correction coding step is used to automatically detect and correct bit errors generated during transmission. After successfully receiving and correctly decoding the data packet, a link layer acknowledgment signal and optional channel quality feedback including a received signal strength indication are sent to the master device.

[0030] In this embodiment, the Bluetooth system-on-a-chip configured in the master device and slave device is the nRF5340; wherein, The application processor core of the nRF5340 is configured to perform data packaging, forward error correction coding, application layer protocol parsing, and the adaptive power control algorithm. The network processor core of the nRF5340 is configured to run the Bluetooth link layer protocol stack and process the physical layer radio frequency timing, connection event scheduling, and the transmission and reception of the link layer acknowledgment signal in hard real-time. The dual-core architecture enables physical isolation and collaborative operation between application processing and radio frequency control, ensuring absolute accuracy and rapid response of radio frequency timing in highly interference-prone underwater environments.

[0031] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for ultra-short-range Bluetooth communication for underwater equipment, characterized in that, The method is applied to a communication system including a master device and a slave device, wherein the master device is an underwater vital signs monitoring module and the slave device is an underwater relay terminal or a teammate device. The method includes the following on the master device side: Step 1, Data Packet Construction: The sensor data or control commands to be transmitted, which are collected or calculated by the vital signs monitoring module, are packaged into a short frame data packet of a preset format; wherein, the sensor data includes one or more of heart rate, blood oxygen saturation, respiratory rate, water depth, temperature and decompression plan information, and the control commands include alarm commands; Step 2, Forward Error Correction Coding: Forward error correction coding is applied to the constructed short frame data packet to generate redundant verification information, and the redundant verification information is appended to the data packet to form an error-resistant enhanced data packet; Step 3, High-intensity radio frequency emission: Configure the operating parameters of the Bluetooth radio frequency unit, set its transmit power to the maximum allowable value supported by the chip, and set its physical layer mode to a coded physical layer mode with high processing gain; with this configuration, the error-resistant enhanced data packet is transmitted to the slave device in an underwater environment. The stable wireless communication link between the master device and the slave device is established and maintained in the underwater near-field range, and its maximum reliable communication distance does not exceed 20 centimeters.

2. The ultra-short-range Bluetooth communication method for underwater equipment according to claim 1, characterized in that, In the data packet construction step, the short frame data packet uses ASCII character encoding to ensure protocol simplicity, and its frame structure includes the following in sequence: A fixed header of one byte, with a value of 0xFF; A one-byte command word used to identify the data type; A two-byte data length field is used to indicate the number of bytes of subsequent payload data; A variable-length payload data field is used to carry the sensor data or control commands; A one-byte check bit, the value of which is the result of a byte-by-byte XOR operation on all bytes from the command word to the last byte of the payload data field; A fixed terminator for a single byte, with a value of 0x0D.

3. The ultra-short-range Bluetooth communication method for underwater equipment according to claim 2, characterized in that, In the high-intensity radio frequency transmission step, the coded physical layer mode specifically refers to the Coded PHY mode defined by Bluetooth 5.0 and above standards. It adopts an S=8 encoding scheme and uses a symbol repetition mechanism to improve the received signal-to-noise ratio in order to combat the severe signal attenuation caused by the underwater environment.

4. The ultra-short-range Bluetooth communication method for underwater equipment according to claim 3, characterized in that, Prior to the high-intensity radio frequency transmission step, a link layer optimization step is also included: a) Configure the Bluetooth connection interval to an extremely short value in the range of 3 to 20 milliseconds to increase the handshake opportunities per unit time and achieve fast retransmission; b) In each successful connection event, enable and utilize the maximum link layer packet length allowed by the Bluetooth protocol for data transmission to compensate for the decrease in effective throughput caused by high retransmission rates.

5. The ultra-short-range Bluetooth communication method for underwater equipment according to claim 4, characterized in that, The method further includes an adaptive power control step: A) Receive channel quality feedback information from the slave device, including an indication of received signal strength; B) Based on the value of the received signal strength indication, dynamically adjust the local transmit power between the maximum allowable transmit power and a lower power level; when the signal quality is good, moderately reduce the power to save energy, and when the signal quality deteriorates, immediately restore to the maximum power to maintain link stability.

6. An ultra-short-range Bluetooth communication system for underwater equipment, characterized in that, It includes a master device and a slave device, both of which are sealed in a watertight structure capable of withstanding hydrostatic pressure of at least 30 meters underwater. The main device is an underwater vital signs monitoring device operated by an ultra-short-range Bluetooth communication method for underwater equipment according to any one of claims 1 to 5. The slave device is configured as follows: Set the receiver sensitivity of its Bluetooth radio frequency unit to the highest level and continuously monitor the communication channel; The radio frequency signal from the master device is captured, demodulated and decoded, and the redundant verification information generated in the forward error correction coding step is used to automatically detect and correct bit errors generated during transmission. After successfully receiving and correctly decoding the data packet, a link layer acknowledgment signal and optional channel quality feedback including a received signal strength indication are sent to the master device.

7. The ultra-short-range Bluetooth communication system for underwater equipment according to claim 6, characterized in that, The Bluetooth system-on-a-chip configured in both the master and slave devices is the nRF5340; wherein, The application processor core of the nRF5340 is configured to perform data packaging, forward error correction coding, application layer protocol parsing, and the adaptive power control algorithm. The network processor core of the nRF5340 is configured to run the Bluetooth link layer protocol stack and process physical layer radio frequency timing, connection event scheduling, and the transmission and reception of the link layer acknowledgment signals in hard real-time.

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