Environment Internet of Things communication method and device

Abstract

The invention provides an environment internet of things communication method and device, and belongs to the technical field of wireless communication, the method combines cyclic redundancy check coding (CRC), block repetition coding, forward error correction coding (FEC), linear coding (containing a small frequency offset mechanism), an OOK modulation technology and an insertion guide code combination, and optimizes coding and modulation strategies to realize communication of the environment internet of things. Different guide code combinations are used according to the data blocks, so that the energy consumption of equipment is effectively reduced, the communication reliability of the passive Internet of Things is remarkably improved, and a technical solution with high efficiency and high robustness is provided 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 the field of wireless communications, a large number of devices will be able to achieve intelligent interconnection in the future. This development trend not only significantly improves productivity and automation levels, but also puts higher performance requirements on existing communication infrastructure. Most of the existing low-power IoT technologies rely on ordinary batteries or button batteries as energy supply. However, at the scale of tens of billions of IoT nodes, battery consumption will increase exponentially, which is contrary to the sustainable development goal of a low-carbon economy. In addition, existing technologies cannot meet the needs of many application scenarios that lack battery power, and passive IoT (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 deficiencies of the prior art 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 the understanding of the overall background of the invention and should not be regarded as an acknowledgment 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 network device at the receiving end performs a modulo division operation on the received uplink data sequence according to the agreed generating polynomial; if the remainder is 0, it means that the data transmission is complete and correct; 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] The passive IoT device performs forward error correction encoding on the data after completing the block repetition operation according to different application scenarios;

[0012] Passive IoT devices linearly encode the forward error correction encoded data according to different application scenarios;

[0013] The passive IoT device uses on-off keying modulation on the uplink signal after linear encoding, and performs 1 / 0 multiplication on the carrier through switch operation; finally, the signal is transmitted to the network device through PDRCH, and the network device filters, demodulates and decodes the uplink data;

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

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

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

[0018] Optionally, the passive Internet of Things 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, which is used for high and low level switching of the signal.

[0020] Optionally, the passive Internet of Things device performs forward error correction encoding on the data after completing the block repetition operation according to different application scenarios:

[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 Internet of Things device linearly encodes the data after forward error correction encoding according to different application scenarios; the encoding methods include Manchester encoding and Miller encoding;

[0023] When Manchester coding is selected for linear coding of passive IoT devices, the coding rule is: when the signal jumps from low level to high level, the signal is recorded as "1"; when the signal jumps from high level to low level, the signal is recorded as "0"; in order to reduce the frequency drift that may be generated by the signal during uplink transmission and reduce the self-interference problem on the network device side, Manchester coding adds a small frequency offset mechanism on the basis of conventional operation; the specific implementation is to repeat the codeword operation R times within the unit bit duration for the completed Manchester coding sequence;

[0024] When passive IoT devices use Miller coding for linear coding, 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 of the bit to indicate data changes. In addition, when multiple bits of "0" appear consecutively in the signal input, a level jump is introduced at the starting position of each bit to ensure the clock synchronization of the signal. 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 in the front, middle and rear parts of the PDRCH specifically as follows:

[0026] According to the data payload size, three types of amble combinations are designed: small payload uses only the preamble; medium payload uses the preamble and postamble; large payload adds two midambles;

[0027] The preamble code consists of 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 is 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 the complete Golay (24,12,8) sequence, which provides high autocorrelation, low cross-correlation and error correction capability, and marks the end of transmission. By constructing the Golay generator matrix, the Goaly 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-term transmission.

[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 method of excitation and energy supply by 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, which meets the development needs of modern Internet of Things technology.

[0038] In addition, the present application provides a passive Internet of Things information interaction device and method thereof, aiming to realize efficient uplink communication between passive devices and network devices. The solution combines cyclic redundancy check coding (CRC), block repetition coding, forward error correction coding (FEC), linear coding (including small frequency offset mechanism), OOK modulation technology and inserted guide code combination, optimizes coding and modulation strategies, 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 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 drawings required for use in the embodiments will be briefly introduced below. 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 creative labor.

[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 A schematic diagram of information interaction for passive IoT relay-assisted transmission provided in an embodiment of the present invention.

[0042] Figure 3 A flowchart of passive Internet of Things data uplink transmission provided by an embodiment of the present invention.

[0043] Figure 4 A schematic diagram of implementing FEC encoding for a passive IoT device provided in an embodiment of the present invention.

[0044] Figure 5 A schematic diagram of implementing linear encoding for a passive Internet of Things device provided in an embodiment of the present invention.

[0045] Figure 6 A schematic diagram of implementing Manchester small frequency offset for a passive Internet of Things device provided in an embodiment of the present invention.

[0046] Figure 7 A schematic diagram of implementing Miller small frequency shift for a passive Internet of Things device provided in an embodiment of the present invention.

[0047] Figure 8 A schematic diagram of implementing a guide code combination for a passive Internet of Things device provided in an embodiment of the present invention.

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

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work 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] Embodiment 1:

[0053] This embodiment provides an environmental Internet of Things communication method and device. Figure 1 A passive IoT application scenario is presented. In this scenario, the present application proposes an information interaction 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, while the A-IoT device feeds back uplink data to the network device through energy acquisition, completing the entire process of two-way communication.

[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 equipment, micro base station equipment, repeaters, pico base station equipment, exciters, readers, access point devices, and user terminals. Network devices can support a variety of communication protocols and standards, such as 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 devices suitable for passive IoT scenarios. These devices can operate without relying on independent power supplies through efficient energy collection and reflection communication technology. Typical forms include backscatterers, reflection terminals, scattering communication devices, environmental tags, and electronic tags. Compared with traditional IoT devices, A-IoT devices can achieve stable communication and data transmission with low energy consumption, and are an important part of IoT technology.

[0056] Figure 2An information interaction architecture of a 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 (Edge Access Device), 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 design of the above architecture can meet the needs of various passive IoT application scenarios, including environmental monitoring, logistics tracking, and smart tags, and improve the 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 device, whose information interaction process can enable the network device or auxiliary node to send downlink data to the passive Internet of Things device through the PRDCH (Physical Reader-to-Device Channel) channel and provide energy support. The passive Internet of Things device obtains the required energy through the energy collection mechanism, and transmits the uplink data back to the network device through the PDRCH (Physical Device-to-Reader Channel) channel in a backscattering manner, thereby completing the information interaction between the network device and the passive Internet of Things device.

[0059] Specifically, during the information exchange process, the network device or auxiliary node first transmits the downlink signal through the PRDCH channel, while carrying the power supply signal to meet the energy needs of the passive IoT device. The passive IoT device captures the power supply signal through the 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. This design not only enables stable data transmission, but also meets the communication needs of passive devices under extremely low power consumption conditions.

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

[0061] In order to enhance the data integrity of passive IoT devices in wireless transmission, the device transmitter will add a binary check code of length m at the end of the uplink data sequence and use the cyclic redundancy check (CRC) method to encode the data. The specific encoding method is flexibly selected according to the length of the uplink data block:

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

[0063] When the length of the uplink data block 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 length of the uplink data block 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 , the m-bit binary check bits are defined as p0, p1, p2, p3, ..., p m-1 After m-bit CRC encoding, the generated polynomial is:

[0068] 0e9 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 is: when b k =a k ,k=0,1,2,...,A-1when b k =p k-A ,k=A,A+1,A+2,...,A+L-1.

[0070] The network device at the receiving end performs a modular division operation on the received uplink data sequence according to the agreed generating polynomial. If the remainder is 0, it means that the data transmission is complete and correct; if the remainder is not 0, it indicates that an error may have occurred during the transmission process.

[0071] 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, assume 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

[0072] The calculation formula for the number of block repetitions R is:

[0073] Where T b Indicates the time required to transmit a complete information bit. Chiplength indicates a smaller unit of the bit period Tb, which is used to define the length of time for the high and low levels of the signal to switch, and can be understood as the time interval for a level to persist. By sending repeated data blocks during signal transmission, even if part of the data is lost due to interference, the receiving end can reorganize and verify the repeated information, thereby ensuring the integrity and reliability of the data.

[0074] After completing the block repetition operation, the passive IoT device will perform forward error correction (FEC) encoding on the repeated data to further improve the anti-interference ability and reliability of data transmission. FEC encoding adopts the Tail-Biting Convolutional Code (TBCC) widely used in LTE. The code rate of this encoder is 1 / 3, which means that for every information bit input, three coding bits will be output, which significantly enhances the redundancy and error correction ability of the data. The generating polynomial of the tail-biting convolutional code is G0=1338, G1=1718, G2=1658, and the constraint length of the encoder is 7, that is, the input data will be affected by the first 6 state bits during the encoding process, forming a more complex encoding output. Figure 4A schematic diagram of implementing FEC encoding in the passive IoT device of this application is given.

[0075] Exemplarily, 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 current bit and the previously stored bit sequence. 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:

[0076]

[0077] The final output coded bit stream d k The three output bits This tail-biting convolutional coding not only has a high error correction efficiency in design, but also avoids the complexity caused by the initialization of traditional convolutional codes through tail bit design, and can further optimize performance and resource usage in hardware implementation.

[0078] 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 selected as 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. Exemplarily, when the linear coding of the passive IoT device uses Manchester coding, 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".

[0079] In order to avoid frequency drift and self-interference problems on the network equipment side during uplink transmission, a small frequency offset operation is further introduced based on the 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 the present 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 It represents 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 repetition number R is 4, that is, in one 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 can not only effectively reduce signal distortion caused by drift in long-distance transmission, but also disperse the spectrum energy, thereby reducing the risk of self-interference at the receiving end.

[0080] When a passive IoT device uses Miller coding, 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 of the bit to indicate data changes. In addition, when the signal input has multiple bits of "0" in succession, a level jump is introduced at the start of each bit to ensure the clock synchronization of the signal.

[0081] Likewise, Figure 7 A schematic diagram of the implementation of Miller small frequency offset code for 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 provides support for 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 or high-interference scenarios, Miller4 or Miller8 can be selected to improve data reliability and decoding accuracy.

[0082] Passive IoT devices use OOK modulation for the uplink signal after linear encoding, and perform 1 / 0 operations through switch operations (on / off) to complete the modulation process of the uplink signal. Specifically, when the signal is "1", the device turns on the RF switch and sends out a 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 very suitable for the low-power communication needs of passive devices. The modulated signal is transmitted to the network device through PDRCH, and the network device filters, demodulates and decodes the received uplink data to achieve correct data restoration and transmission integrity.

[0083] In order to effectively solve the timing drift problem caused by sampling frequency offset (SFO) during long-term transmission of uplink data, this application proposes an innovative solution to optimize the transmission performance of the signal by introducing preamble, midamble and postamble in the PDRCH transmission link. These preambles can help network devices accurately estimate and timely correct the timing deviation caused by SFO, thereby significantly improving the performance of the receiver and the reliability of communication.

[0084] Specifically, the preamble, postamble, and midamble play a role in different stages of data transmission, working together to ensure accurate data transmission. The preamble is used in the initial stage to help the receiving device synchronize the timing; the midamble is located in the middle of the data transmission to correct the timing drift; the postamble is located at the end of the transmission to further correct and restore the timing.

[0085] 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:

[0086] Small payload (20 bits): For transmission of small payload, only the preamble is used to simplify the transmission process and save bandwidth resources.

[0087] Medium load (96 bits): For medium load data transmission, a combination of preamble and postamble is used. This solution can provide more stable communication performance while ensuring timing correction, and is suitable for application scenarios with large data volumes.

[0088] Large payload (400 bits): For data transmission with large payload, a combination of preamble, two midambles and postamble is used. This solution can provide more precise timing correction and recovery during long-term data transmission, ensuring accurate data transmission to the greatest extent, and is suitable for application scenarios requiring high data integrity and low bit error rate.

[0089] The specific structure design of the preamble, midamble and postamble of uplink data transmission is as follows: Preamble has good correlation and is mainly used for sampling frequency training and timing acquisition. Its structure can be divided into two parts: sampling frequency training signal and timing acquisition signal:

[0090] 1. Sampling frequency training signal: To improve the robustness and transmission efficiency of the signal, the sampling frequency training signal is designed to be a 24-bit all-1 sequence (i.e., each bit is 1). After Manchester coding with a coding rate of 1 / 2, the sequence is converted into a sequence of 48 chips, i.e., (a total of 48 chips).

[0091] 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. The sequence is also Manchester encoded 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.

[0092] 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.

[0093] In order to save device storage resources and reduce implementation complexity, the midamble in this application directly reuses the timing acquisition signal part of the preamble. In the specific implementation, the PDRCH data is divided into three parts, and a midamble is inserted between each part. This method not only saves storage and computing resources, but also further enhances the timing synchronization and frequency correction performance during the long-term transmission of large data.

[0094] The post-amble is mainly used to mark the end of PDRCH transmission, and to further enhance the tracking and estimation capabilities of SFO in coordination with the preamble and midamble. To avoid interference with the preamble, the post-amble is designed differently 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: Fig. 9 As shown, it has good cross-correlation characteristics and error correction performance. It encodes 12 bits of information bits into 24 bits of 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:

[0095] 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 the matrix P is generated by cyclically shifting the previous row by one position. After the matrix is ​​constructed, it can be used to encode Golay codewords.

[0096] 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, and is used to generate a corresponding Golay codeword.

[0097] S903: Use the Golay generator matrix G to perform matrix multiplication on the input information vector u to generate a complete Goaly codeword v. The matrix multiplication is performed modulo 2 (i.e., bitwise XOR operation) to encode the input 12-bit information vector into a Golay codeword with a length of 24 bits. Exemplarily, for the input information vector u, the Golay codeword calculation formula is: v=u·G.

[0098] S904: The generated Golay codeword is embedded as the timing acquisition part of the postamble to mark the end of PDRCH transmission and assist in enhancing timing synchronization and frequency correction performance. In this process, the postamble is designed to be orthogonal to the preamble to avoid signal interference.

[0099] S905: Verify the cross-correlation between the post-amble and the pre-amble. Define the cross-correlation function Calculate the correlation between the two, where k is the delay value. The value range of the delay value k is -23≤k≤23. The verification process must meet the following conditions:

[0100] 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.

[0101] 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.

[0102] S906: Select the Golay sequence with the lowest mutual correlation as the final post-amble. By calculating the mutual correlation function of the candidate sequences one by one, select the Golay sequence that meets the conditions. Exemplarily, the selected Golay sequence can be expressed as: v = [x1, x2, ..., x 24 ].

[0103] 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.

[0104] Finally, the A-IOT device flexibly selects the preamble combination according to the load size of the uplink transmission and transmits the uplink data to the network device end. 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 end only needs to be able to receive the uplink data, and does not need to perform timing alignment operations to save transmission resources.

[0105] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0106] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood 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 network device at the receiving end performs a modulo division operation on the received uplink data sequence according to the agreed generating polynomial; if the remainder is 0, it means that the data transmission is complete and correct; 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; The passive IoT device performs forward error correction encoding on the data after completing the block repetition operation according to different application scenarios; Passive IoT devices linearly encode the forward error correction encoded data according to different application scenarios; The passive IoT device uses on-off keying modulation on the uplink signal after linear encoding, and performs 1 / 0 multiplication on the carrier through switch operation; finally, the signal is transmitted to the network device through PDRCH, and the network device filters, demodulates and decodes the uplink data; The passive IoT device inserts the preamble, midamble and postamble into the front, middle and rear parts of the PDRCH.

2. The environmental Internet of Things communication method according to claim 1, characterized in that: The passive IoT device receives the 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 as follows: The transmitting end of the device adds a binary check code of length m at 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 encoding with a generation rule suitable for short data is used. When the data block length exceeds 24 bits, a 16-bit CRC encoding 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, which is 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 completing the block repetition operation according to different application scenarios, specifically: 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 coding is selected for linear coding of passive IoT devices, the coding rule is: when the signal jumps from low level to high level, the signal is recorded as "1"; when the signal jumps from high level to low level, the signal is recorded as "0". In order to reduce the frequency drift that may be generated by the signal during uplink transmission and reduce the self-interference problem on the network device side, Manchester coding adds a small frequency offset mechanism on the basis of conventional operation; the specific implementation is to repeat the codeword operation R times within the unit bit duration for the completed Manchester coding sequence; When passive IoT devices use Miller coding for linear coding, 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 of the bit to indicate data changes. In addition, when multiple bits of "0" appear consecutively in the signal input, a level jump is introduced at the starting position of each bit to ensure the clock synchronization of the signal. 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.

6. The environmental Internet of Things communication method according to claim 1, characterized in that: The passive IoT device inserts the preamble, midamble and postamble in the front, middle and rear parts of the PDRCH as follows: According to the data payload size, three types of amble combinations are designed: small payload uses only the preamble; medium payload uses the preamble and postamble; large payload adds two midambles; The preamble code consists of 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 is 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 the complete Golay (24,12,8) sequence, which provides high autocorrelation, low cross-correlation and error correction capability, and marks the end of transmission. By constructing the Golay generator matrix, the Goaly 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-term transmission.

7. An environmental Internet of Things communication device according to the environmental Internet of Things communication method 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 interaction process between the network device, the auxiliary node and the passive IoT device, the network device or the 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 energy 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.

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