A method and device for environmental Internet of Things communication

Abstract

The present invention provides an environmental Internet of Things communication method and device, which belongs to the field of wireless communication technology. The present invention combines cyclic redundancy check coding (CRC), block repetition coding, forward error correction coding (FEC), linear coding (including a small frequency offset mechanism), OOK modulation technology and inserted guide code combination, optimizes the coding and modulation strategy, uses different guide code combinations according to data blocks, effectively reduces equipment energy consumption, and significantly improves the reliability of passive Internet of Things communication, providing a technical solution with high efficiency and high robustness for related fields.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to an environmental Internet of Things communication method and device. Background Art

[0002] With the rapid development of IoT technology in wireless communications, a vast number of devices will be intelligently connected in the future. This trend not only significantly improves productivity and automation, but also places higher performance demands on existing communications infrastructure. Existing low-power IoT technologies mostly rely on conventional batteries or button cells for energy supply. However, with tens of billions of IoT nodes, battery consumption will increase exponentially, which is inconsistent with the sustainable development goals of a low-carbon economy. Furthermore, existing technologies cannot meet the needs of many application scenarios that lack battery power. Ambient IoT (A-IoT) technology provides a practical solution to this challenge.

[0003] The present invention responds to the technical requirements of 3GPP in the field of passive Internet of Things and proposes a communication method and device for ultra-low complexity and ultra-low power consumption applications, aiming to address the shortcomings of existing technologies and provide efficient and reliable technical support for the actual deployment of passive Internet of Things.

[0004] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0005] The object of the present invention is to provide a communication method and device for ultra-low complexity and ultra-low power consumption applications.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] An environmental Internet of Things communication method, comprising:

[0008] The passive IoT device receives the downlink data sent by the network device and uses the energy carried in it to backscatter uplink data transmission to the network device through the PDRCH;

[0009] The receiving network device performs a modular division operation on the received uplink data sequence according to the agreed generator polynomial. If the remainder is 0, the data transmission is complete and error-free. If the remainder is not 0, it indicates that an error may have occurred during the transmission process.

[0010] The passive IoT device performs block repetition on the CRC-encoded data;

[0011] Passive IoT devices perform forward error correction encoding on the data after completing block repetition operations according to different application scenarios;

[0012] Passive IoT devices perform linear encoding on the forward error correction encoded data according to different application scenarios;

[0013] The passive IoT device uses on-off keying modulation on the linearly encoded uplink signal, performing 1 / 0 multiplication on the carrier through switching operations. The signal is then transmitted to the network device via the PDRCH, which filters, demodulates, and decodes the uplink data.

[0014] The passive IoT device inserts the preamble, midamble, and postamble into the front, middle, and back parts of the PDRCH.

[0015] Optionally, the passive IoT device receives downlink data sent by the network device and uses the energy carried therein to perform backscatter uplink data transmission to the network device via the PDRCH. Specifically:

[0016] The transmitting end of the device adds a binary check code of length m at the end of the uplink data sequence and encodes the data using a cyclic redundancy check method. The specific encoding method is flexibly selected based on the length of the uplink data block:

[0017] When the data block length does not exceed 24 bits, a 6-bit CRC code with a generation rule suitable for short data is used. When the data block length exceeds 24 bits, a 16-bit CRC code with a stronger verification rule is used.

[0018] Optionally, the passive IoT device performs a block repetition operation on the CRC-encoded data, specifically:

[0019] The calculation formula for the number of repetitions R is R=Tb / (2*chip length), where Tb represents the time required to transmit a complete information bit, and chip length represents a smaller time unit of the bit period Tb, used for high and low level switching of the signal.

[0020] Optionally, the passive IoT device performs forward error correction encoding on the data after the block repetition operation is completed according to different application scenarios, specifically:

[0021] Select a tail-biting convolutional code with a code rate of 1 / 3 and a constraint length of 7, whose polynomial is G0=133 8, G1=1718,G2=1658.

[0022] Optionally, the passive IoT device performs linear encoding on the forward error correction encoded data according to different application scenarios; the encoding methods include Manchester encoding and Miller encoding;

[0023] When Manchester coding is selected for linear coding in passive IoT devices, the coding rule is as follows: when the signal transitions from a low level to a high level, the signal is recorded as a "1"; when the signal transitions from a high level to a low level, the signal is recorded as a "0". To reduce frequency drift that may occur during uplink transmission and mitigate self-interference issues on the network device side, Manchester coding adds a small frequency offset mechanism to the conventional operation. This is specifically implemented by repeating the completed Manchester coding sequence R times within the unit bit duration.

[0024] When passive IoT devices use Miller coding for linear encoding, the coding rules are as follows: when the signal input is bit "0", the level state remains unchanged and no jump between high and low levels occurs; when the signal input is bit "1", a jump between high and low levels is introduced in the middle position of the bit to indicate data changes. In addition, when the signal input has multiple bits of "0" consecutively, to ensure the clock synchronization of the signal, a level jump is introduced at the starting position of each bit. According to the number of subcarriers contained in each bit, Miller coding is further divided into Miller2, Miller4 and Miller8, corresponding to coding forms containing 2, 4 and 8 subcarriers per bit, respectively, to meet the needs of various communication scenarios.

[0025] Optionally, the passive Internet of Things device inserts the preamble, midamble, and postamble into the front, middle, and back parts of the PDRCH specifically as follows:

[0026] Three amble combinations are designed based on the data payload size: small payload uses only the preamble; medium payload uses the preamble and postamble; large payload adds two midambles;

[0027] The preamble consists of two parts: a sampling frequency signal of a 24-bit all-1 sequence and a timing acquisition signal of a 24-bit binary sequence with good correlation, which are used for frequency correction and timing synchronization;

[0028] The midamble multiplexes the timing of the preamble to obtain the signal sequence to simplify storage and enhance the correction performance of long-term transmission;

[0029] The post-amble adopts a complete Golay (24,12,8) sequence, which provides high autocorrelation, low cross-correlation and error correction capability, and also indicates the end of transmission. By constructing a Golay generator matrix, a Golay sequence is generated according to the input vector, and the cross-correlation of the post-amble and preamble timing acquisition signals is calculated. The sequence that meets the orthogonality requirement is screened out, and different amble combinations are selected according to the size of the transmitted message block to solve the timing drift problem caused by the sampling frequency offset caused by long transmission time.

[0030] An environmental Internet of Things communication device, comprising:

[0031] Network equipment, passive IoT devices, and auxiliary nodes;

[0032] The network device is used to send downlink data to the passive Internet of Things device and provide energy support;

[0033] The passive Internet of Things device is used to return the processed uplink data to the network device;

[0034] The auxiliary node is located between the network device and the passive Internet of Things device, and is used to receive downlink data sent by the network device and uplink data sent by the passive Internet of Things device.

[0035] Optionally, during the information interaction process among the network device, auxiliary node and passive IoT device, the network device or auxiliary node first transmits a downlink signal through the PRDCH channel, while carrying a power supply signal to meet the energy requirements of the passive IoT device; the passive IoT device captures the power supply signal through a built-in energy collection module, and uses efficient backscatter communication technology to return the processed uplink data to the network device or auxiliary node through the PDRCH channel.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention provides an environmental Internet of Things communication method and device. Existing traditional radio frequency identification (RFID) devices generally rely on manual battery replacement, and their signal coverage range is usually only a few meters. There are problems such as long time consumption and high cost during use. In order to solve the above technical defects, this application proposes a passive Internet of Things communication method and device based on the target scenario defined by 3GPP TR38.848. Through the excitation and energy supply of radio frequency equipment, there is no need for manual battery replacement or frequent charging, thereby significantly reducing operating costs, while having the advantages of energy saving and environmental protection, meeting the development needs of modern Internet of Things technology.

[0038] In addition, the present application provides a device and method for passive Internet of Things information interaction, aiming to achieve efficient uplink communication between passive devices and network devices. This solution combines cyclic redundancy check (CRC), block repetition coding, forward error correction (FEC), linear coding (including a small frequency offset mechanism), OOK modulation technology, and inserted guide code combination. By optimizing the coding and modulation strategy and using different guide code combinations based on the data block, it effectively reduces device energy consumption and significantly improves the reliability of passive Internet of Things communication, providing a high-performance and high-robustness technical solution for related fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 A schematic diagram of information interaction of a passive Internet of Things provided by an embodiment of the present invention.

[0041] Figure 2 Schematic diagram of information interaction for passive IoT relay-assisted transmission provided by an embodiment of the present invention.

[0042] Figure 3 This is a flowchart of the passive IoT data uplink transmission provided by an embodiment of the present invention.

[0043] Figure 4 A schematic diagram of implementing FEC coding in a passive IoT device according to an embodiment of the present invention.

[0044] Figure 5 Schematic diagram of linear encoding implemented by a passive IoT device provided in an embodiment of the present invention.

[0045] Figure 6 Schematic diagram of the Manchester small frequency offset implemented by the passive IoT device provided in an embodiment of the present invention.

[0046] Figure 7 Schematic diagram of implementing Miller small frequency offset for a passive IoT device provided in an embodiment of the present invention.

[0047] Figure 8 A schematic diagram of a guide code combination implemented by a passive IoT device according to an embodiment of the present invention.

[0048] Figure 9 A schematic diagram of the design process for a post-amble sequence for a passive IoT device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] The object of the present invention is to provide a communication method and device for ultra-low complexity and ultra-low power consumption applications.

[0051] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] Example 1:

[0053] This embodiment provides an environmental Internet of Things communication method and device. Figure 1 This paper presents a passive IoT application scenario. In this scenario, this application proposes an information exchange architecture between a passive IoT device (A-IoT device) and a network device. The network device not only provides excitation energy but also sends downlink data to the A-IoT device. The A-IoT device, in turn, feeds uplink data back to the network device through energy harvesting, completing the entire two-way communication process.

[0054] In an embodiment of the present invention, a network device refers to a radio frequency communication device that can provide energy support for other devices and realize wireless signal transmission. These devices may be in the form of macro base station devices, micro base station devices, repeaters, pico base station devices, exciters, readers, access point devices, and user terminals. Network devices can support multiple communication protocols and standards, such as those based on the fifth-generation mobile communication technology (5G New Radio, NR) architecture, or backward compatible with the fourth-generation long-term evolution (4G Long Term Evolution, LTE) network. For specific application scenarios, network devices can also be combined with Internet of Things protocols to achieve diversified functional expansion.

[0055] A-IoT devices are a type of ultra-low-power, low-complexity terminal device suitable for passive IoT scenarios. These devices utilize efficient energy harvesting and reflective communication technologies, allowing them to operate without relying on a separate power source. Typical forms include backscatterers, reflective terminals, scattering communication devices, environmental tags, and electronic tags. Compared to traditional IoT devices, A-IoT devices enable stable communication and data transmission with low energy consumption, making them a crucial component of IoT technology.

[0056] Figure 2An information interaction architecture for passive IoT relay-assisted communication in an embodiment of the present invention is shown. In this architecture, by introducing auxiliary nodes, communication between network devices and A-IoT devices can be efficiently achieved. The auxiliary nodes can not only provide energy supply for A-IoT devices, but also serve as communication relay nodes to improve the coverage and stability of the link while forwarding uplink or downlink data. Auxiliary nodes come in various forms, such as integrated access backhaul nodes (IAB), repeaters (RP), user equipment (UE), edge access devices (EDD), etc. In addition, according to actual needs, the auxiliary nodes can further integrate edge computing functions to process part of the data locally, thereby reducing the computing load of the network core.

[0057] The above architecture is designed to meet the needs of various passive IoT application scenarios, including environmental monitoring, logistics tracking, and smart tags, and improves overall system performance by optimizing energy efficiency and communication quality.

[0058] like Figure 1 and Figure 2 As shown, the present invention provides a communication method and apparatus, whose information exchange process enables a network device or auxiliary node to send downlink data and provide energy support to a passive IoT device via the PRDCH (Physical Reader-to-Device Channel). The passive IoT device obtains the required energy through an energy harvesting mechanism and transmits uplink data back to the network device via the PDRCH (Physical Device-to-Reader Channel) by backscattering, thus completing information exchange between the network device and the passive IoT device.

[0059] Specifically, during information exchange, the network device or auxiliary node first transmits a downlink signal over the PRDCH channel, carrying a power supply signal to meet the energy needs of the passive IoT device. The passive IoT device captures the power supply signal through a built-in energy harvesting module and, using efficient backscatter communication technology, returns the processed uplink data to the network device or auxiliary node over the PDRCH channel. This design not only ensures stable data transmission but also meets the communication needs of passive devices with extremely low power consumption.

[0060] Figure 3 The diagram shows a method for transmitting uplink data signals of a passive IoT device in an embodiment of the present application. The passive IoT device generates uplink bit data of the passive IoT at the transmitting end.

[0061] To enhance the data integrity of passive IoT devices during wireless transmission, the device transmitter adds a binary checksum of length m to the end of the uplink data sequence and uses a cyclic redundancy check (CRC) method to encode the data. The specific encoding method is flexibly selected based on the length of the uplink data block:

[0062] When the data block length does not exceed 24 bits, a 6-bit CRC encoding is used, using a generation rule suitable for short data. This rule effectively performs data integrity verification under low-complexity conditions while maintaining high detection capabilities. When the data block length exceeds 24 bits, a 16-bit CRC encoding with a more stringent verification rule is used. This rule is suitable for longer data blocks, providing higher reliability in complex scenarios and reducing the possibility of data transmission errors.

[0063] When the uplink data block length does not exceed 24 bits, a 6-bit CRC code is used, and the corresponding generating polynomial is:

[0064] g CRC6 (D)=[D 6 +D 5 +1]

[0065] When the uplink data block length exceeds 24 bits, a 16-bit CRC code is used, and the corresponding generating polynomial is:

[0066] g CRC16 (D)=[D 16 +D 11 +D 6 +D 5 +1]

[0067] For example, assume that the passive IoT data is defined as a0, a1, a2, a3, ..., a k-1 ,m-bit binary check bits are defined as p0,p1,p2,p3,...,p m-1 After m-bit CRC encoding, the generating polynomial is:

[0068] a0 k+m-1 +a1D k+m-2 +...+a k-1 D L +p0D m-1 +p1D m-2 +...+p m-2 D 1 +p m-1 That is, the data bits after CRC encoding are defined as: b0, b1, b2, b3, ..., b B-1 , where B = k + m. k and bk The relationship between b is: k =a k ,k=0,1,2,...,A-1when b k =p k-A ,k=A,A+1,A+2,...,A+L-1.

[0069] The receiving network device performs a modular division on the received uplink data sequence based on the agreed generator polynomial. If the remainder is 0, the data transmission is complete and error-free. If the remainder is not 0, it indicates that an error may have occurred during the transmission process.

[0070] After completing the CRC encoding, the passive IoT device will perform block repetition on the generated data block to enhance the reliability and anti-interference ability of the transmission. Specifically, assuming that the data block after CRC encoding is defined as: a0, a1, a2, a3, d0, d1, d2, where a0, a1, a2, a3, are the core data part of the passive IoT device (i.e., A-IOT data), and d0, d1, d2 are the added CRC encoding suffixes. Through the block repetition operation, the original data block will be copied multiple times to form a repeated data sequence, and the data after the block repetition operation is

[0071] The calculation formula for the number of block repetitions R is:

[0072] Where T b The chiplength represents the time required to transmit a complete information bit. It is a smaller unit of the bit period Tb and defines the duration of the signal's high and low level transitions. It can be understood as the time interval during which a level persists. By sending repeated data blocks during signal transmission, even if some data is lost due to interference, the receiving end can reassemble and verify the repeated information, thus ensuring data integrity and reliability.

[0073] After completing the block repetition operation, passive IoT devices perform forward error correction (FEC) encoding on the repeated data to further improve data transmission immunity and reliability. FEC encoding utilizes the tail-biting convolutional code (TBCC), widely used in LTE. This coder has a code rate of 1 / 3, meaning that for every input information bit, three coded bits are output, significantly enhancing data redundancy and error correction capabilities. The generator polynomials for the TBCC are G0 = 1338, G1 = 1718, and G2 = 1658, and the encoder constraint length is 7. This means that the input data is affected by the first six state bits during encoding, resulting in a more complex coded output. Figure 4A schematic diagram of the passive IoT device implementing FEC coding is given.

[0074] For example, the input information bit c after the block repetition operation k Enter the shift register in sequence, and the state of the shift register is updated to the bit at the current moment and the bit sequence stored previously. The content of the shift register at each moment is [c k ,c k-1 ,…,c k-6 ] Calculate the three output bits according to the generating polynomial The specific calculation formula is:

[0075]

[0076] The final output coded bit stream d k The three output bits mentioned above This tail-biting convolutional coding not only has high error correction efficiency in design, but also avoids the complexity caused by traditional convolutional code initialization through tail bit design, which can further optimize performance and resource usage in hardware implementation.

[0077] Passive IoT devices further perform linear encoding on the FEC-encoded data based on specific application scenario requirements to adapt to the requirements of different data transmission environments. Figure 5 A schematic diagram of linear coding implemented by the passive IoT device of the present application is given. The linear coding schemes may be Manchester coding and Miller coding. Manchester coding (also known as phase-split coding) is a typical bipolar coding scheme. Its core principle is to distinguish between binary bits 0 and 1 by the jump of the signal level, thereby achieving self-synchronization of data and reducing the bit error rate. For example, when Manchester coding is used for linear coding of a passive IoT device, the coding rule is that when the signal jumps from a low level to a high level, the signal is recorded as "1", that is, the "1" bit is mapped to "01"; when the signal jumps from a high level to a low level, the signal is recorded as "0", that is, the "0" bit is mapped to "10".

[0078] To avoid frequency drift and self-interference on the network equipment side during uplink signal transmission, a small frequency offset operation is further introduced on the basis of traditional Manchester coding. That is, the Manchester coded codeword is repeated R times. The small frequency offset is achieved by repeating the basic Manchester code. Figure 6 A schematic diagram of the Manchester small frequency offset code implemented by the passive IoT device of this application is given. In the small frequency offset operation, each Manchester codeword transmits one bit in the time Tb is repeated R times, the number of repetitions is: Similar to block repetition, where T b Indicates the time required to transmit a complete information bit, and chip length represents the bit period T b It defines the duration of high and low level switching in the signal. Assume that T b The value is 1 microsecond, the chip length is 0.125 microseconds, and the value of the repetition number R is 4, that is, in a T b The corresponding high and low levels in the signal are repeated 4 times. Through this repetitive operation, the frequency distribution of the signal is slightly shifted, and the small frequency shift (in Hertz) is calculated as This frequency offset not only effectively reduces signal distortion caused by drift during long-distance transmission, but also disperses spectrum energy, thereby reducing the risk of self-interference at the receiving end.

[0079] When passive IoT devices use Miller coding, the encoding rules are as follows: When the signal input is a "0" bit, the level remains unchanged, with no transitions between high and low levels. When the signal input is a "1" bit, a transition between high and low levels is introduced at the middle of the bit to indicate the data change. Furthermore, when the signal input contains multiple consecutive "0" bits, a level transition is introduced at the beginning of each bit to ensure clock synchronization.

[0080] Likewise, Figure 7 A schematic diagram of the implementation of Miller small frequency offset code in the passive IoT device of this application is given. In the coding implementation, Miller coding follows the UHF RFID standard and is further refined into three main modes according to the number of subcarriers contained in each bit period: Miller2, Miller4, and Miller8, corresponding to 2, 4, and 8 subcarriers per bit period, respectively. This division method supports the flexible use of Miller coding in different application scenarios. For example, in low-rate transmission scenarios, Miller2 can be selected to reduce power consumption; in high-rate scenarios or scenarios with high anti-interference requirements, Miller4 or Miller8 can be selected to improve data reliability and decoding accuracy.

[0081] Passive IoT devices use OOK modulation on the linearly encoded uplink signal, performing 1 / 0 operations through on / off switching to complete the uplink signal modulation process. Specifically, when the signal is "1", the device turns on the RF switch and transmits the carrier signal; when the signal is "0", the device turns off the RF switch and stops transmitting the carrier signal. This simple and efficient modulation method is well suited for the low-power communication requirements of passive devices. The modulated signal is transmitted via the PDRCH to the network device, which filters, demodulates, and decodes the received uplink data to ensure accurate data restoration and transmission integrity.

[0082] To effectively address the timing drift problem caused by sampling frequency offset (SFO) during long-term uplink data transmission, this application proposes an innovative solution to optimize signal transmission performance by introducing preamble, midamble, and postamble into the PDRCH transmission link. These preambles can help network devices accurately estimate and promptly correct the timing deviation caused by SFO, thereby significantly improving receiver performance and communication reliability.

[0083] Specifically, the preamble, postamble, and midamble play different roles at different stages of data transmission, working together to ensure accurate data transmission. The preamble is used at the beginning to help the receiving device synchronize timing; the midamble is located in the middle of the data transmission to correct timing drift; and the postamble is used at the end of the transmission to further correct and restore timing.

[0084] According to the requirements of different transmission loads, this application designs three different guide code combination schemes to meet the needs of various application scenarios, and Figure 8 The specific implementation method is shown:

[0085] Small payload (20 bits): For transmission of small payload, only the preamble is used to simplify the transmission process and save bandwidth resources.

[0086] Medium payload (96 bits): For medium payload data transmission, a combination of preamble and postamble is used. This solution ensures timing correction while providing more stable communication performance and is suitable for applications with large data volumes.

[0087] Large payload (400 bits): For data transmission with large payloads, a combination of a preamble, two midambles, and a postamble is used. This solution provides more precise timing correction and recovery during long data transmissions, ensuring data transmission accuracy to the greatest extent possible. It is suitable for applications requiring high data integrity and a low bit error rate.

[0088] The specific structure of the preamble, midamble, and postamble for uplink data transmission is designed as follows: The preamble has good correlation and is mainly used for sampling frequency training and timing acquisition. Its structure can be divided into two parts: the sampling frequency training signal and the timing acquisition signal:

[0089] 1. Sampling frequency training signal: To improve signal robustness and transmission efficiency, the sampling frequency training signal is designed as a 24-bit all-1 sequence (i.e., every bit is 1). This sequence is converted into a 48-chip sequence (48 chips in total) after Manchester encoding with a coding rate of 1 / 2.

[0090] 2. Timing acquisition signal: The timing acquisition signal uses a 24-bit binary sequence with high correlation. The specific design is {h0,h1,h2,...,h L-2 ,h L-1}={0,0,0,1,...,1,1,0,1}, where the ellipsis in the middle represents repeated 1. This sequence is also Manchester coded with a coding rate of 1 / 2 to generate a timing acquisition signal sequence with a length of 48 chips. 00 ,h 01 ,h 10 ,h 11 ,h 20 ,h 21 ,...,h (L-2)0 ,h (L-2)1 ,h (L-1)0 ,h (L-1)1}={1, 0, 1, 0, 1, 0, 0, 1, ..., 0, 1, 0, 1, 1, 0, 0, 1} (48 chips in total), where the ellipsis in the middle represents repeated {0, 1}, L=24.

[0091] The sampling frequency training signal and the timing acquisition signal together constitute the complete structure of the Preamble, with a total length of 96 chips, and are inserted in front of the PDRCH.

[0092] To conserve device storage resources and reduce implementation complexity, the midamble in this application directly reuses the timing acquisition signal portion of the preamble. In the specific implementation, the PDRCH data is divided into three equal parts, with a midamble segment inserted between each part. This approach not only conserves storage and computing resources but also further enhances timing synchronization and frequency correction performance during long-term transmission of large amounts of data.

[0093] The main function of the post-amble is to mark the end of the PDRCH transmission, and to further enhance the tracking and estimation capabilities of the SFO in conjunction with the preamble and midamble. In order to avoid interference with the preamble, the post-amble adopts a different design from the preamble. Specifically, the post-amble in this application uses the Golay (24, 12, 8) sequence. The specific design flow chart is as follows: Figure 9 As shown, it has good cross-correlation characteristics and error correction performance. It encodes 12 bits of information into 24-bit codewords, providing redundancy for information during transmission so that error correction and anti-interference processing can be performed at the receiving end. The design steps include:

[0094] s901: Construct a 12*24 Golay generator matrix G, G=[I 12 |P]. The generated matrix includes a 12*12 identity matrix I 12 and generated by the polynomial g(x)=x 11 +x 9 +x 7 +x 6 +x 5 +1 defines a 12*12 circulant matrix P. Each row of matrix P is generated by cyclically shifting the previous row right by one position. Once constructed, the matrix can be used to encode Golay codewords.

[0095] s902: Input a 12-bit information vector u, which can come from a system-defined fixed value, a pseudo-random sequence, or a dynamically generated control signal, to generate the corresponding Golay codeword.

[0096] S903: Use the Golay generator matrix G to perform matrix multiplication on the input information vector u to generate a complete Goaly codeword v. Matrix multiplication is performed modulo 2 (i.e., a bitwise exclusive-OR operation), encoding the 12-bit input information vector into a 24-bit Golay codeword. For example, for the input information vector u, the Golay codeword calculation formula is: v = u·G.

[0097] S904: The generated Golay codeword is embedded as the timing acquisition portion of the postamble to mark the end of PDRCH transmission and help enhance timing synchronization and frequency correction performance. In this process, the postamble is designed to be orthogonal to the preamble to avoid signal interference.

[0098] S905: Verify the cross-correlation between the post-amble and the preamble. Define the cross-correlation function Calculate the correlation between the two, where k is the delay value. The range of the delay value k is -23≤k≤23. The verification process must meet the following conditions:

[0099] When k is equal to 0 at the zero delay point, the cross-correlation value Rpost-pre(0) between the post-amble and the preamble should be significantly lower than the main autocorrelation peak value Rpost-post(0) of the post-amble to ensure orthogonality.

[0100] When k is not equal to 0 at all non-zero delay points, the cross-correlation value Rpost-pre(k) should be close to zero to avoid interference.

[0101] S906: Filter the Golay sequence with the lowest cross-correlation as the final post-amble. By calculating the cross-correlation function of the candidate sequences one by one, select the Golay sequence that meets the conditions. For example, the selected Golay sequence can be expressed as: v = [x1, x2, ..., x 24 ].

[0102] After the encoding is completed, the selected Golay sequence is represented by Manchester coding with a code rate of 1 / 2, converted into a total of 48 chips, and inserted immediately after the PDRCH.

[0103] Ultimately, the A-IOT device flexibly selects a preamble combination based on the size of the uplink transmission payload and transmits the uplink data to the network device. The network device receives the uplink signal. In some embodiments, the receiving device performs at least the following operations on the uplink signal: bandpass filtering, low-pass filtering, envelope detection, demodulation, decoding, SFO estimation, and timing alignment to achieve uplink information transmission. It should be noted that when the load is small, that is, only the preamble is used, the network device only needs to receive the uplink data and does not need to perform timing alignment operations to save transmission resources.

[0104] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0105] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. An environmental Internet of Things communication method, characterized in that: include: The passive IoT device receives the downlink data sent by the network device and uses the energy carried in it to backscatter uplink data transmission to the network device through the PDRCH; The receiving network device performs a modular division operation on the received uplink data sequence according to the agreed generator polynomial. If the remainder is 0, it indicates that the data transmission is complete and error-free. If the remainder is not 0, it indicates that an error may have occurred during the transmission process. The passive IoT device performs block repetition on the CRC-encoded data; Passive IoT devices perform forward error correction encoding on the data after completing block repetition operations according to different application scenarios; Passive IoT devices perform linear encoding on the forward error correction encoded data according to different application scenarios; The passive IoT device uses on-off keying modulation on the linearly encoded uplink signal, performing 1 / 0 multiplication on the carrier through switching operations. The signal is then transmitted to the network device via the PDRCH, which filters, demodulates, and decodes the uplink data. The passive IoT device inserts the preamble, midamble, and postamble into the front, middle, and back parts of the PDRCH.

2. The environmental Internet of Things communication method according to claim 1, characterized in that: The passive IoT device receives downlink data sent by the network device and uses the energy carried therein to perform backscatter uplink data transmission to the network device via the PDRCH. Specifically: The transmitting end of the device adds a binary check code of length m to the end of the uplink data sequence and uses the cyclic redundancy check method to encode the data. The specific encoding method is flexibly selected according to the length of the uplink data block: When the data block length does not exceed 24 bits, a 6-bit CRC code with a generation rule suitable for short data is used. When the data block length exceeds 24 bits, a 16-bit CRC code with a stronger verification rule is used.

3. The environmental Internet of Things communication method according to claim 1, characterized in that: The passive IoT device performs a block repetition operation on the CRC-encoded data, specifically: The calculation formula for the number of repetitions R is R=Tb / (2*chip length), where Tb represents the time required to transmit a complete information bit, and chip length represents a smaller time unit of the bit period Tb, used for high and low level switching of the signal.

4. The environmental Internet of Things communication method according to claim 1, characterized in that: The passive IoT device performs forward error correction coding on the data after the block repetition operation according to different application scenarios as follows: Select a tail-biting convolutional code with a code rate of 1 / 3 and a constraint length of 7, whose polynomial is G0=133 8, G1=1718,G2=1658.

5. The environmental Internet of Things communication method according to claim 1, characterized in that: The passive IoT device linearly encodes the data after forward error correction encoding according to different application scenarios; the encoding methods include Manchester encoding and Miller encoding; When Manchester encoding is selected for linear coding in passive IoT devices, the encoding rule is: when the signal transitions from a low level to a high level, the signal is recorded as a "1"; when the signal transitions from a high level to a low level, the signal is recorded as a "0". To reduce frequency drift that may occur during uplink transmission and mitigate self-interference issues on the network device side, Manchester encoding adds a small frequency offset mechanism to the conventional operation. This is achieved by repeating the completed Manchester encoding sequence R times within the unit bit duration. When passive IoT devices use Miller coding for linear encoding, the coding rules are as follows: when the signal input is a "0" bit, the level state remains unchanged, and no transitions occur between high and low levels. When the signal input is a "1" bit, a transition between high and low levels is introduced at the middle of the bit to indicate data changes. In addition, when the signal input contains multiple consecutive "0" bits, a level transition is introduced at the beginning of each bit to ensure clock synchronization of the signal. Based on the number of subcarriers contained in each bit, Miller coding is further divided into Miller2, Miller4, and Miller8, corresponding to coding forms containing 2, 4, and 8 subcarriers per bit, respectively, to meet the needs of various communication scenarios.

6. The environmental Internet of Things communication method according to claim 1, characterized in that: The passive Internet of Things device inserts the preamble, midamble and postamble into the front, middle and back parts of the PDRCH as follows: Three amble combinations are designed based on the data payload size: small payload uses only the preamble; medium payload uses the preamble and postamble; large payload adds two midambles; The preamble consists of two parts: a sampling frequency signal of a 24-bit all-1 sequence and a timing acquisition signal of a 24-bit binary sequence with good correlation, which are used for frequency correction and timing synchronization; The midamble multiplexes the timing of the preamble to obtain the signal sequence to simplify storage and enhance the correction performance of long-term transmission; The post-amble adopts a complete Golay (24,12,8) sequence, which provides high autocorrelation, low cross-correlation and error correction capability, and also indicates the end of transmission. By constructing a Golay generator matrix, a Golay sequence is generated according to the input vector, and the cross-correlation of the post-amble and preamble timing acquisition signals is calculated. The sequence that meets the orthogonality requirement is screened out, and different amble combinations are selected according to the size of the transmitted message block to solve the timing drift problem caused by the sampling frequency offset caused by long transmission time.

7. An environmental Internet of Things communication device according to any one of claims 1 to 6, characterized in that: include: Network equipment, passive IoT devices, and auxiliary nodes; The network device is used to send downlink data to the passive Internet of Things device and provide energy support; The passive Internet of Things device is used to return the processed uplink data to the network device; The auxiliary node is located between the network device and the passive Internet of Things device, and is used to receive downlink data sent by the network device and uplink data sent by the passive Internet of Things device.

8. The environmental Internet of Things communication device according to claim 7, characterized in that: During the information exchange process between the network device, auxiliary node and passive IoT device, the network device or auxiliary node first transmits a downlink signal through the PRDCH channel, while carrying an energy supply signal to meet the energy demand of the passive IoT device; The passive IoT device captures the power supply signal through a built-in energy harvesting module and uses efficient backscatter communication technology to return the processed uplink data to the network device or auxiliary node through the PDRCH channel.

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