WO2024146543A1 - Subcarrier modulation method and apparatus for backscatter communication, and communication device - Google Patents

Abstract

The present application relates to the technical field of communications, and discloses a subcarrier modulation method and apparatus for backscatter communication, and a communication device. The subcarrier modulation method for backscatter communication in embodiments of the present application comprises: a second device receives first information sent by a first device, the first information comprising a subcarrier modulation type of a first signal, the subcarrier modulation type comprising dual-frequency modulation and/or single-frequency modulation, and the subcarrier dual-frequency modulation comprising: a first modulation mode, which indicates that a backscatter frequency band comprises Q subcarriers, wherein Q is less than N (101); the second device performs subcarrier modulation on the first signal according to the first information to obtain a backscatter signal (102); and the second device sends the backscatter signal to the first device (103), wherein N is the number of subcarriers comprised in an orthogonal frequency-division multiplexing (OFDM) symbol.

Description

Subcarrier modulation method and device for backscatter communication, and communication equipment

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese Patent Application No. 202310014614.4 filed in China on January 5, 2023, the entire contents of which are incorporated herein by reference.

Technical Field

The present application belongs to the field of communication technology, and specifically relates to a subcarrier modulation method and device for backscatter communication, and communication equipment.

Background technique

Related modulation technologies, including amplitude modulation, phase modulation, amplitude-phase two-dimensional modulation, etc., all require system synchronization, otherwise the demodulation performance will be affected. However, for backscatter devices with limited capabilities, their synchronization capabilities are weak and it is difficult to maintain synchronization with the transmitter.

One of the technologies that is insensitive to the synchronization error between the transmitting and receiving ends is the subcarrier shift keying technology. Although the subcarrier shift keying technology is insensitive to the synchronization error between the transmitting and receiving ends, there is a problem that the stability of the crystal oscillator leads to frequency deviation error and high requirements on the accuracy of the crystal oscillator.

Summary of the invention

Embodiments of the present application provide a subcarrier modulation method and apparatus, and a communication device for backscatter communication.

In a first aspect, a subcarrier modulation method for backscatter communication is provided, comprising:

The second device receives first information sent by the first device, where the first information includes a subcarrier modulation type of the first signal, where the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, where the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode indicating that the reverse scattering frequency band includes Q subcarriers, where Q is less than N;

The second device performs subcarrier modulation on the first signal according to the first information to obtain a backscattered signal;

The second device sends the backscatter signal to the first device;

Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol.

In a second aspect, a subcarrier modulation device for backscatter communication is provided, comprising:

A first receiving module is configured to receive first information sent by a first device, wherein the first information includes a subcarrier modulation type of a first signal, wherein the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, and the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode indicating that a reverse scattering frequency band includes Q subcarriers, where Q is less than N;

A modulation module, configured to perform subcarrier modulation on the first signal according to the first information to obtain a backscattered signal;

A first sending module, configured to send the backscattered signal to the first device;

Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol.

In a third aspect, a subcarrier modulation method for backscatter communication is provided, comprising:

The first device sends first information to the second device, where the first information includes a subcarrier modulation type of the first signal, where the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, where the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode, indicating that the reverse scattering frequency band includes Q subcarriers, where Q is less than N;

The first device receives a backscatter signal sent by the second device, where the backscatter signal is obtained by performing subcarrier modulation on the first signal;

The first device demodulates the backscattered signal according to the first information;

Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol.

In a fourth aspect, a subcarrier modulation device for backscatter communication is provided, comprising:

A second sending module is used to send first information to a second device, where the first information includes a subcarrier modulation type of the first signal, where the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, where the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode, indicating that the reverse scattering frequency band includes Q subcarriers, where Q is less than N;

A second receiving module, used to receive a backscattered signal sent by the second device, where the backscattered signal is obtained by subcarrier modulating the first signal;

A demodulation module, configured to demodulate the backscattered signal according to the first information;

Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol.

In a fifth aspect, a second device is provided, comprising a processor and a communication interface, wherein the communication interface is used to receive first information sent by a first device, the first information comprising a subcarrier modulation type of a first signal, the subcarrier modulation type comprising dual-frequency modulation and/or single-frequency modulation, the subcarrier modulation type of the dual-frequency modulation comprising: a first modulation mode, indicating that the reverse scatter frequency band includes Q subcarriers, Q is less than N; the processor is used to perform subcarrier modulation on the first signal according to the first information to obtain a backscatter signal; the communication interface is used to send the backscatter signal to the first device.

In a sixth aspect, a second device is provided, which communication device includes a processor and a memory, wherein the memory stores a program or instruction that can be executed on the processor, and when the program or instruction is executed by the processor, the steps of the method described in the first aspect are implemented.

In the seventh aspect, a first device is provided, comprising a processor and a communication interface, wherein the communication interface is used to send first information to a second device, the first information including a subcarrier modulation type of a first signal, the subcarrier modulation type including dual-frequency modulation and/or single-frequency modulation, the subcarrier modulation type of the dual-frequency modulation including: a first modulation mode, indicating that the backscattered frequency band includes Q subcarriers, Q is less than N; receiving a backscattered signal sent by the second device, the backscattered signal being obtained by subcarrier modulating the first signal; the processor is used to demodulate the backscattered signal according to the first information.

In an eighth aspect, a first device is provided, the communication device comprising a processor and a memory, the memory storing a program or instruction that can be run on the processor, the program or instruction being executed by the processor to implement a third party The steps of the method described above.

In the ninth aspect, a communication system is provided, comprising: a first device and a second device, wherein the second device can be used to execute the steps of the subcarrier modulation method for backscatter communication as described in the first aspect, and the first device can be used to execute the steps of the subcarrier modulation method for backscatter communication as described in the third aspect.

In the tenth aspect, a readable storage medium is provided, on which a program or instruction is stored. When the program or instruction is executed by a processor, the steps of the method described in the first aspect are implemented, or the steps of the method described in the third aspect are implemented.

In the eleventh aspect, a chip is provided, comprising a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run a program or instruction to implement the method described in the first aspect, or to implement the method described in the third aspect.

In the twelfth aspect, a computer program/program product is provided, which is stored in a storage medium and executed by at least one processor to implement the subcarrier modulation method for backscatter communication as described in the first aspect, or to implement the steps of the subcarrier modulation method for backscatter communication as described in the third aspect.

In an embodiment of the present application, a first device sends first information to a second device, the first information including a subcarrier modulation type of a first signal, the subcarrier modulation type including dual-frequency modulation and/or single-frequency modulation, the subcarrier modulation type of the dual-frequency modulation including: a first modulation mode, indicating that the reverse scattered frequency band includes Q subcarriers, Q is less than N; when the second device performs single-frequency modulation, the single-frequency modulation uses a clock to modulate the subcarrier, and there is no need to use two clocks at the same time to achieve frequency offset, thereby reducing the requirements for the crystal oscillator accuracy of the second device, or reducing the hardware complexity of the second device; when the second device performs dual-frequency modulation, the reverse scattered frequency band may include Q subcarriers, and there are empty subcarriers in the reverse scattered frequency band. The introduction of empty subcarriers can solve the problem of frequency deviation error caused by the stability of the crystal oscillator, which further causes interference between subcarriers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a block diagram of a wireless communication system to which an embodiment of the present application can be applied;

FIG2 is a schematic diagram of a backscatter communication application scenario;

FIG3 is a schematic diagram of a typical architecture of a single base and a dual base;

Fig. 4 is a schematic diagram of ASK, PSK and FSK modulation;

FIG5 is a modulation principle diagram of QAM modulation achieved through a power divider;

FIG6 is a schematic diagram of OFDM subcarrier backscattering technology;

FIG7 is a schematic diagram of a tag changing subcarrier pattern;

FIG8 is a schematic diagram of the process of subcarrier shift keying technology;

9 is a schematic flow chart of a subcarrier modulation method for backscatter communication on the second device side according to an embodiment of the present application;

10 is a schematic flow chart of a subcarrier modulation method for backscatter communication on the first device side according to an embodiment of the present application;

FIG11 is a schematic diagram of a modulation process of a second device in a specific embodiment of the present application;

FIG12 is a schematic diagram of a first device decoding a backscattered signal according to a specific embodiment of the present application;

FIG13 is a schematic diagram of another specific embodiment of the present application using an “OFDM symbol repetition” modulation mode;

FIG14 is a schematic diagram of another specific embodiment of the present application using a "position information type" modulation mode;

FIG15 is a schematic diagram of the structure of a communication device according to an embodiment of the present application;

FIG16 is a schematic diagram of the structure of a terminal according to an embodiment of the present application;

FIG. 17 is a schematic diagram of the structure of the network side device according to an embodiment of the present application.

Detailed ways

The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of this application.

The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way are interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first" and "second" are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and/or" in the specification and claims represents at least one of the connected objects, and the character "/" generally represents that the objects associated with each other are in an "or" relationship.

It is worth noting that the technology described in the embodiments of the present application is not limited to the Long Term Evolution (LTE)/LTE-Advanced (LTE-A) system, but can also be used in other wireless communication systems, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single-carrier Frequency Division Multiple Access (SC-FDMA) and other systems. The terms "system" and "network" in the embodiments of the present application are often used interchangeably, and the described technology can be used for the above-mentioned systems and radio technologies as well as for other systems and radio technologies. The following description describes a new radio (NR) system for example purposes, and NR terms are used in most of the following descriptions, but these technologies can also be applied to applications other than NR system applications, such as the ^6th Generation (6G) communication system.

FIG1 shows a block diagram of a wireless communication system applicable to an embodiment of the present application. The wireless communication system includes a terminal 11 and a network side device 12. The terminal 11 may be a mobile phone, a tablet computer (Tablet Personal Computer), a laptop computer (Laptop Computer) or a notebook computer, a personal digital assistant (Personal Digital Assistant, PDA), a handheld computer, a netbook, an ultra-mobile personal computer (ultra-mobile personal computer, UMPC), a mobile Internet device (Mobile Internet Device, MID), an augmented reality (augmented reality, AR)/virtual reality (virtual reality, VR) device, a robot, a wearable device (Wearable Device), a vehicle user equipment (VUE), a pedestrian terminal (Pedestrian User Equipment, PUE), a smart home (a home appliance with wireless communication function, such as a refrigerator, a television, a washing machine or furniture, etc.), a game console, a personal computer (personal The terminal side devices 12 include: computer, PC), ATM or self-service machine, and wearable devices include: smart watches, smart bracelets, smart headphones, smart glasses, smart jewelry (smart bracelets, smart bracelets, smart rings, smart necklaces, smart anklets, smart anklets, etc.), smart wristbands, smart clothing, etc. It should be noted that the specific type of terminal 11 is not limited in the embodiment of the present application. The network side device 12 may include access network equipment or core network equipment, wherein the access network equipment may also be called wireless access network equipment, wireless access network (Radio Access Network, RAN), wireless access network function or wireless access network unit. The access network device may include a base station, a wireless local area network (WLAN) access point or a wireless fidelity (WiFi) node, etc. The base station may be called a node B, an evolved node B (eNB), an access point, a base transceiver station (BTS), a radio base station, a radio transceiver, a basic service set (BSS), an extended service set (ESS), a home node B, a home evolved node B, a transmission reception point (TRP) or some other suitable term in the field. As long as the same technical effect is achieved, the base station is not limited to a specific technical vocabulary. It should be noted that in the embodiment of the present application, only the base station in the NR system is used as an example for introduction, and the specific type of the base station is not limited.

Backscatter Communication (BSC) refers to the use of radio frequency signals from other devices or environments to modulate signals to transmit information. Backscatter communication equipment can be:

The backscatter communication device in traditional Radio Frequency Identification (RFID) is generally a tag, including the following:

Passive-Internet of Things (Passive-IoT) devices have no energy storage capacitors and/or batteries and rely on environmental signals for energy and communication;

Semi-passive tags have energy storage capacitors and/or batteries and rely on environmental signals for energy storage and communication. The downlink reception or uplink reflection of such tags may have a certain amplification capability, i.e., optionally, the semi-passive tags have amplifiers.

Active tags have energy storage capacitors and/or batteries and actively generate carriers for communication. Such terminals can send information to gNBs or readers without relying on reflection of incident signals. Optionally, active tags have amplifiers.

A simple implementation method is that when the tag needs to send a ‘1’, the tag reflects the incident carrier signal, and when the tag needs to send a ‘0’, it does not reflect and absorbs the signal.

Backscatter communication equipment controls the reflection coefficient Γ of the circuit by adjusting its internal impedance, thereby changing the amplitude, frequency, phase, etc. of the incident signal to achieve signal modulation. The reflection coefficient of the signal can be characterized as:

Where _Z0 is the antenna characteristic impedance and _Z1 is the load impedance. Assuming the incident signal is S _in (t), the output signal is Therefore, corresponding amplitude modulation, frequency modulation or phase modulation can be achieved by properly controlling the reflection coefficient.

The maximum power of normal terminal communication is at least 23dBm. When the maximum power is much lower than this value, such as -20dBm, it is considered extremely low power communication. In this case, it may be necessary to use a different method from Orthogonal Frequency Division Multiplexing (OFDM). Frequency Division Multiplexing (OFDM) modulation method, such as binary amplitude keying (On-Off Keying, OOK) modulation method.

The backscatter communication application scenario is shown in Figure 2. The base station (BS) sends continuous wave (CW) and signaling to the tag. Figure 3 is a schematic diagram of the typical architecture of single base and dual base.

Considering the cost and energy consumption of the tag, the backscattered signal is usually modulated by Amplitude Shift Keying (ASK), Phase Shift Keying (PSK), Frequency Shift Keying (FSK) or mixed modulation. The modulation principle is mainly to change the amplitude, phase or frequency of the reflection coefficient by switching different impedance elements. If the RF source is a LoRa signal, Chirp Spread Spectrum (CSS) modulation can be achieved by linearly changing the switching frequency.

ASK provides continuous tag transmission power, and tag signal demodulation is relatively easy to achieve. However, when using ASK, the tag signal is easily affected by interference and noise. Therefore, some related literature proposes differential modulation technology to overcome the influence of interference and noise, but differential modulation has the disadvantage of high bit error rate. FSK also has strong adaptability to interference and noise, but the spectrum utilization of FSK is half of that of ASK.

Figure 4 shows the schematic diagram of ASK, PSK and FSK modulation. ASK modulation requires at least two load impedances, and the working principle of 2ASK modulation is used as an example to illustrate.

Assume that the antenna impedance is ZA, the load impedance is ZL, and the reflection coefficient is Γ:

Furthermore, the expressions for the reflection coefficient amplitude |Γ| and phase θ can be given as:

Here, α represents a certain constant.

It can be seen from equation (5) that in order to make the phase of the reflection coefficient 0, it is necessary to assume that the phase of the load impedance is equal to the phase of the antenna impedance. If the backscatter device sends a bit "1", the antenna should be connected to a load impedance with an impedance value of 0, so that the reflection coefficient is 1, and the backscatter device completely reflects the incident signal; if the backscatter device sends a bit "0", the antenna should be connected to a load impedance with an impedance value equal to the antenna impedance value, so that the reflection coefficient is 0, and the backscatter device absorbs the incident signal.

The principle of PSK modulation is similar to that of ASK modulation. PSK modulation can be achieved by selecting different load impedances. Taking Binary Phase Shift Keying (BPSK) modulation as an example, the phase corresponding to the load impedance value should be 90° different from the phase corresponding to the antenna impedance value to ensure that the amplitude of the reflection coefficient does not change under different load impedance connections. If the backscatter device sends a bit "0", the antenna should be connected to a load impedance with a load impedance amplitude of 0, so that the phase of the modulated signal is 0°; if the backscatter device sends a bit "1", the antenna should be connected to a load impedance with a load impedance amplitude equal to the antenna impedance amplitude, so that the phase of the modulated signal is 180°.

For FSK modulation, its modulation principle is different from the implementation method of ASK and PSK. Taking 2FSK modulation as an example, if the tag wants to implement 2FSK modulation, it is necessary to control the on-off frequency of the RF switch through the microcontroller unit (MCU) to generate square wave signals of different frequencies corresponding to bit "1" and bit "0". 2FSK can be implemented by a single load impedance or by two load impedances. If the impedance values of the two load impedances are located at the open circuit point and the short circuit point of the Smith original diagram, that is, the impedance values of the two load impedances are infinite and 0, then the absolute value of the reflection coefficient can always be 1, ensuring that the power of the backscattered signal is maximized. Assuming that the impedance value of _Z1 is infinite, the impedance value of _Z2 is 0, and Δf represents the frequency difference, the reflection coefficient can be expressed as:

Assume that the incident signal is After 2FSK modulation, the backscatter signal S _bs can be expressed as:
S _bs =ΓS _in (7)

Since the square wave function is a periodic function, it can be expressed by Fourier series. Taking the first harmonic component of the square wave function, equation (7) can be converted to:

It can be seen from equation (8) that the backscattered signal becomes a double-sideband signal with a frequency deviation of Δf.

Quadrature Amplitude Modulation (QAM) is a typical high-order modulation technology. Due to the hardware cost and energy limitations of backscatter communication equipment, high-order modulation can only be achieved from the RF circuit. For example, a combination of transistors and power dividers is used to implement 16QAM modulation in backscatter communication equipment. The modulation principle diagram of QAM modulation through a power divider is shown in Figure 5. A 3dB Wilkinson power divider with equal power is used to divide the incoming wave signal into two paths, I and Q. The two branches have a phase difference of 45°, while the reflected wave phase of the I branch differs from the reflected wave phase of the Q branch by 90°.

The reflected wave b in Figure 5 is the sum of the reflected waves of the two branches, I and Q. According to the properties of the Wilkinson power divider, the reflected wave b can be expressed as:

Among them, Γ ₁ and Γ ₂ represent the reflection coefficients of the I path and Q path respectively, and the corresponding load impedances Z ₁ and Z ₂ can be expressed as:

Therefore, the reflection coefficient of the backscatter communication device can be expressed as:

It can be seen from equation (11) that if 4QAM modulation is to be implemented in a backscatter communication device, two different load impedances need to be connected to the rear end of the power divider in order to generate four different reflection coefficients.

Since the traditional PSK modulation method is highly dependent on synchronization accuracy, its symbol timing offset (STO) and carrier frequency offset (CFO) have high requirements. When the tag uses PSK modulation, its synchronization error will affect the bit error rate of signal demodulation at the receiving end. In addition, if BPSK modulation is used, each symbol only carries 1 bit of information.

Figure 6 shows an OFDM subcarrier backscattering technology, which uses subcarrier shift keying modulation to represent different tag information through different subcarrier patterns. The tag receives the original OFDM symbol (N subcarriers) sent by the reader, and the bit to be transmitted is 000010. The bit information to be transmitted is converted into a decimal number of 2. Therefore, through the radio frequency (RF) on-off keying method, the last two subcarriers in the original OFDM symbol are cyclically shifted to the position of the first two subcarriers to form a new subcarrier pattern. Compared with the original pattern, the subcarriers in the new pattern are cyclically shifted by 2 subcarrier positions in a forward-to-backward order, corresponding to the information to be transmitted by the tag.

Compared with traditional PSK modulation, subcarrier shift keying technology has the following advantages:

An OFDM symbol has N subcarriers, and the maximum number of transmitted bits is log ₂ N;

Can reduce the requirements for synchronization accuracy;

Able to be compatible with larger STOs and CFOs.

The specific scheme of tag changing subcarrier pattern is shown in Figure 7. The specific implementation steps are: 1) extracting specific subcarriers: mapping the bit information of the tag to be modulated into different subcarrier patterns; 2) frequency shifting the extracted part of the subcarriers; 3) splicing frequency shifting: splicing the extracted part of the subcarriers with the remaining subcarriers.

However, this solution has the following problems:

1) The tag needs to use a filter with a very high center frequency and a very narrow bandwidth to extract a specific subcarrier. For example, the center frequency of the filter is 2.4 GHz and the bandwidth is 15 kHz. However, it is impossible to design such an analog filter.

2) The frequency band of OFDM signal is relatively wide (such as 20MHz), which requires the clock frequency and precision generated by the tag to be high, and conventional frequency synthesis methods are not applicable. For example, using a phase-locked loop for traditional digital frequency synthesis: using 20MHz bandwidth WiFi signal transmission 1 and 2, 20.3125MHz and 20.625MHz clocks are required, requiring a clock source above 1GHz, and such technology does not meet the requirements of low power consumption and low cost of RFID.

3) When using tandem frequency shift technology, when interference with a strength similar to that of the reflected symbol is introduced on the reverse scattering frequency band, the traditional decoding scheme will not be able to demodulate the required information.

Figure 8 shows a flow chart of the subcarrier shift keying (SSK) technology. Taking the tag bit to be transmitted as 010 as an example, its decimal value is 2; based on this value, the tag uses the serial frequency shift technology to convert the OFDM symbol The subcarriers are moved by 2 and 66 respectively; the subcarrier pattern on the reverse scatter frequency band is the result of cyclic shift of the original symbol subcarrier pattern.

It is worth noting that when using the serial frequency shifting technology, assuming that _f1 is the OFDM frequency band bandwidth to shift the original OFDM symbol 2 subcarriers to the frequency of the reflection band, and _f2 is the OFDM frequency band bandwidth to shift the original OFDM symbol 2+64 subcarriers to the frequency of the reflection band, two switches are used to realize the frequency deviation simultaneously. Assuming that the subcarrier spacing (SCS) is 15KHz, the realization of subcarrier splicing in the reverse scattering frequency band can be realized using an analog filter with a bandwidth of 64×15KHz.

During demodulation, the original OFDM symbol and the backscattered OFDM symbol are received in the original channel and the reflected channel respectively, and the original OFDM symbol and the backscattered OFDM symbol are demodulated in turn. Then, the original symbol and the reflected symbol are decoded and correlated through the decoded information to obtain the position of the peak of the time domain correlation result, thereby realizing the demodulation of the tag bit data.

Related modulation technologies, including amplitude modulation, phase modulation, amplitude-phase two-dimensional modulation, etc., all require system synchronization, otherwise the demodulation performance will be affected. However, for backscatter devices with limited capabilities, their synchronization capabilities are weak and it is difficult to maintain synchronization with the transmitter. One of the technologies that is insensitive to synchronization errors between the transmitter and receiver is subcarrier shift keying technology.

Compared with the traditional tandem frequency shift technology, the advantage of using subcarrier shift keying technology lies in converting the difficulty of subcarrier shift in tandem frequency shift technology into a tag to achieve subcarrier shift through two frequency deviations. This solution can still achieve tag data demodulation even in the case of STO, CFO, strong noise and strong interference on the reverse scattered frequency band. Although subcarrier shift keying technology is not sensitive to synchronization errors at the transmitting and receiving ends, the following problems still exist:

1) The stability of the crystal oscillator causes frequency deviation error, which further leads to inter-carrier interference (ICI);

2) Two clocks need to be used simultaneously to achieve frequency offset, which places high demands on hardware;

3) The modulation bits of the tag are limited. Since the number of subcarriers in an OFDM symbol is 64, the maximum number of bits that can be modulated in an OFDM symbol is 6.

The subcarrier modulation method for backscatter communication provided in the embodiment of the present application is described in detail below through some embodiments and their application scenarios in combination with the accompanying drawings.

The embodiment of the present application provides a subcarrier modulation method for backscatter communication, as shown in FIG9 , including:

Step 101: A second device receives first information sent by a first device, where the first information includes a subcarrier modulation type of a first signal, where the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, where the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode, indicating that a reverse scattering frequency band includes Q subcarriers, where Q is less than N;

Step 102: The second device performs subcarrier modulation on the first signal according to the first information to obtain a backscattered signal;

Step 103: The second device sends the backscattered signal to the first device;

Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol.

In an embodiment of the present application, a first device sends first information to a second device, where the first information includes a subcarrier modulation type of a first signal, where the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, where the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode indicating that a reverse scattering frequency band includes Q subcarriers, where Q is less than N; When the second device performs single-frequency modulation, the single-frequency modulation uses one clock to modulate the subcarrier, and there is no need to use two clocks at the same time to achieve frequency offset, which reduces the requirements for the crystal oscillator accuracy of the second device, or reduces the hardware complexity of the second device; when the second device performs dual-frequency modulation, the reverse scattered frequency band may include Q subcarriers, and there are empty subcarriers in the reverse scattered frequency band. The introduction of empty subcarriers can solve the problem of frequency offset error caused by the stability of the crystal oscillator, which further leads to interference between subcarriers.

The first device is selected from a base station, a reader, a relay node and a terminal, and the second device is selected from a tag and a terminal;

In some embodiments, the first device is a base station, a reader or a relay, and the second device is a tag; or

The first device is a terminal and the second device is a tag; or

The first device is a relay or a base station, and the second device is a terminal.

The label includes at least one of the following:

Passive tags, without energy storage capacitors and/or batteries, rely on environmental signals for energy and communication, do not have carrier generation capabilities, and have the lowest power consumption;

Semi-passive tags have energy storage capacitors and/or batteries, rely on environmental signals for energy storage and communication, and optionally have power amplifiers (PA)/low noise amplifiers (LNA) or other active devices. They do not have carrier generation capabilities and have the lowest power consumption.

Active tags have energy storage capacitors and/or batteries, rely on non-RF signals for power supply, have carrier generation capabilities, consume the most power, and optionally have a PA/low noise amplifier.

Wherein, the dual-frequency modulation uses two clock frequencies to modulate the subcarrier simultaneously;

The single frequency modulation uses a clock frequency to modulate the subcarrier.

When the second device adopts dual-frequency modulation, the second device simultaneously realizes subcarrier modulation through two frequency offsets, realizes subcarrier modulation through different frequency offsets, and is insensitive to the synchronization error of the transmitting and receiving ends; when the second device adopts single-frequency modulation, the second device realizes subcarrier modulation through one frequency offset, which can reduce the hardware requirements.

In this embodiment, the first signal may be a carrier signal, wherein the carrier signal is divided into an energy supply carrier signal and a communication carrier signal, or a carrier signal integrating energy supply and communication. The energy supply carrier signal is mainly used for energy storage and/or modulation by the second device, while the communication carrier signal is mainly a carrier for data bit transmission by the second device. If the second device has the ability to generate a carrier signal, the first signal may be generated by the second device itself. The communication carrier signal may also be a carrier signal carrying information, such as a carrier signal based on OOK modulation and/or BPSK modulation, and the carrier signal may be a single-frequency continuous wave, a frequency-modulated continuous wave, OFDM, etc.

The first signal may also be a reference signal that does not contain any transmission information, such as the LTE/NR synchronization and reference signals in the related technology, including synchronization signal and physical broadcast channel (Synchronization Signal and PBCH block, SSB), channel state information reference signal (Channel State Information Reference Signal, CSI-RS), demodulation reference signal, etc.

In some embodiments, when the second device does not have the capability of generating a carrier signal, the method further includes any one of the following:

The second device receives the first signal sent by the fourth device;

The second device receives the first signal sent by the first device;

The second device receives the first signal sent by the third device, where the first signal is generated by the third device according to parameter configuration information configured by the first device.

The parameter configuration information of the first signal includes at least one of the following:

Signal type, the signal type includes at least one of the following: a radio frequency signal for energy storage; a radio frequency signal for communication; a radio frequency signal for demodulation; a radio frequency signal for energy storage and modulation;

Time domain resources;

Frequency domain resources;

Bandwidth information;

Waveform type;

Guard interval;

Signal power.

In some embodiments, the receiving, by the second device, of the first information sent by the first device includes any one of the following:

The second device receives the first information configured and sent by the first device;

The second device receives the first information sent by the first device, where the first information is a third-party device configuration;

The second device receives the first information forwarded by the first device via the third device.

This embodiment is applicable to a single-base architecture and a dual-base architecture. The single-base architecture refers to that the sender of the first signal and the receiver of the backscattered signal are both the first device. When the receiver of the backscattered signal is a device different from the first device, it is a dual-base architecture, and the device is referred to as the third device here.

In some embodiments, under a single-base architecture, the first device may configure the first information and send the configured first information to the second device; or, the first device may configure the first information and send the configured first information to the second device, and the fourth device may send the first signal to the second device, wherein the fourth device is controlled by the first device and is responsible for sending the first signal to the second device; or, a third-party device may configure the first information, and the third-party device may send the first information to the first device and the second device, and the first device may send the first signal to the second device.

In some embodiments, under a dual-base architecture, the first device may configure the first information and parameter configuration information of the first signal, the first device sends the first information to the second device, the first device sends the parameter configuration information of the first signal to the third device, the third device generates the first signal according to the parameter configuration information of the first signal, and the third device sends the first signal to the second device; or, the first device configures the first information, the first device sends the first information to the third device, and the third device forwards the first information to the second device, and the first device sends the first signal to the second device; or, the first device configures the first information, the first device sends the first information to the third device, and the third device forwards the first information to the second device, the fourth device sends the first signal to the second device, and the fourth device is controlled by the first device; or, the third-party device configures the first information, the third-party device sends the first information to the first device, the second device, and the third device, and the first device sends the first signal to the second device; or, the third-party device configures the first information, the third-party device sends the first information to the first device, the second device, and the third device, and the first device sends the parameter configuration information of the first signal to the third device, The third device generates a first signal according to the parameter configuration information of the first signal, and sends the first signal to the second device.

In this embodiment, the first information is used to indicate relevant information in subcarrier modulation, including subcarrier modulation type, and may also include subcarrier modulation information, subcarrier pattern, etc. When the second device has the ability to actively generate subcarriers, the first information should include the subcarrier pattern, or the subcarrier pattern may be predefined by the protocol.

The subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation. Dual-frequency modulation requires two clocks to modulate the subcarrier simultaneously. The subcarrier modulation type of the dual-frequency modulation includes:

The second modulation mode indicates that the reverse scattered frequency band includes N subcarrier patterns, where N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol, that is, "full carrier" modulation, for example, the reverse scattered frequency band includes a new 64 subcarrier pattern;

The first modulation mode indicates that the reverse scattered frequency band includes Q subcarriers, where Q is less than N, that is, "intermittent" modulation. There are empty subcarriers in the reverse scattered frequency band, and the number of empty subcarriers is N-Q. For example, the new subcarrier pattern contains only 63 subcarriers, and there is 1 empty subcarrier in the reverse scattered frequency band. Because there is 1 empty subcarrier, the introduction of an empty subcarrier can solve the problem of frequency deviation error caused by the stability of the crystal oscillator, which further leads to interference between subcarriers.

Single frequency modulation requires only one clock modulation subcarrier. The subcarrier modulation types of the single frequency modulation include:

The third modulation mode indicates that the number of subcarriers that can be modulated by the second device is K*N, where K is a positive integer, that is, "OFDM symbol repetition" modulation. The second device transmits repeated OFDM symbols, such as two OFDM symbols of the same pattern, constituting 128 subcarriers. In this way, the maximum number of bits that can be modulated is 7, and the number of modulated bits of the tag can be increased;

The fourth modulation mode indicates that P bits to be transmitted are modulated to the left or right, where P is a positive integer, that is, "azimuth information" modulation. Modulating to the left or modulating to the right represents 1 bit to be transmitted. For example, modulating to the left represents bit 1, and modulating to the right represents bit 0. In this way, the maximum number of bits that can be modulated is 7, which can increase the number of modulated bits of the tag.

In some embodiments, the subcarrier modulation information includes at least one of the following: subcarrier spacing, frequency offset indication information, time domain resources, and frequency domain resources.

In some embodiments, the frequency deviation indication information includes at least one of the following:

Frequency offset type, indicating whether the frequency offset is an integer multiple or non-integer multiple of the subcarrier spacing; when the frequency offset is an integer multiple of the subcarrier spacing, assuming the subcarrier spacing is MKHz, the frequency offset value should be TM, where T is a positive integer greater than or equal to 0; when the frequency offset is a non-integer multiple of the subcarrier spacing, assuming the subcarrier spacing is MKHz, the frequency offset value should be LM, where L is a non-integer greater than or equal to 0;

Frequency offset range. When the subcarrier modulation type is dual-frequency modulation, the dual-frequency modulation corresponds to two frequency offset ranges, and the maximum frequency offset of each frequency offset range is the product of the number of subcarriers N and the subcarrier interval M; when the subcarrier modulation type is single-frequency modulation, the single-frequency modulation corresponds to a frequency offset range, and its maximum frequency offset should be guaranteed not to exceed the center frequency of the backscatter frequency band to avoid the appearance of more empty subcarriers in the backscatter signal, which affects the demodulation performance.

In some embodiments, there is a mapping relationship between the frequency offset range and the bit information to be transmitted by the second device. The mapping relationship is carried in the first information sent by the first device to the second device; or The mapping relationship is predefined by the protocol; or, the mapping relationship is carried in the first information forwarded by the first device via the third device; or, the mapping relationship is sent by the fourth device to the second device, and the fourth device provides the second device with a radio frequency carrier signal; or, the mapping relationship is sent by a third-party device to the second device. In this way, the frequency offset range can be implicitly indicated without the need to indicate the frequency offset range through special signaling.

In some embodiments, the frequency offset is an integer multiple of the subcarrier spacing, and modulation is achieved based on the subcarrier frequency offset, that is, when the frequency offset value is P (P is an integer) subcarrier spacings, the decimal number of the bit information that can be carried is log ₂ P. For example, when the frequency offset value is 8 subcarrier spacings, the decimal number of the bit information to be transmitted by the second device is 3, and the corresponding bits are 011.

In some embodiments, the frequency offset is a non-integer multiple of the subcarrier spacing, and modulation is implemented based on the subcarrier frequency offset, that is, when the frequency offset value is L (L is a non-integer) subcarrier spacings, the decimal number of the bit information that can be carried is log ₂ L, which satisfies the rounding rule. For example, when the frequency offset value is 7.5 subcarrier spacings, the decimal number of the bit information to be transmitted by the second device is approximately 2.9, and the corresponding bits are 011.

In some embodiments, before the second device receives the first information sent by the first device, the method further includes:

The second device reports its own capability information to the first device, so that the first device can learn the capability information of the second device and further configure the first information according to the capability information of the second device.

The capability information includes at least one of the following:

Device type, indicating whether it has carrier generation capability. Devices with carrier generation capability are active devices, while devices without carrier generation capability are passive or semi-passive devices.

Analog filter parameters, including passband bandwidth, center frequency and cutoff frequency, and stopband suppression;

Frequency deviation capability parameters, including first level duration, first level switching period, frequency modulation capability of the varactor diode, and other hardware capabilities related to the frequency modulation capability;

Oscillator capability parameters, including crystal frequency, for example, a reference clock source of 14.318 MHz; and clock frequency, for example, frequency shift capability corresponding to the number of subcarriers of 2, 4, 8, 16, or 32;

The number and value of load impedance;

Power amplifier PA parameters;

Rectification parameters of the rectifier.

In some embodiments, the method further comprises:

The second device receives second information sent by the first device, where the second information includes at least one of the following:

The coding indication information includes FM0, i.e., bi-phase interval code coding; and Miller, i.e., Miller code;

Modulation indication information, such as whether the subcarrier modulation used is subcarrier shift keying SSK;

The frequency resource configuration of the first information includes a subband, a resource unit (resource block/resource element, etc.);

The time domain resource configuration of the first information.

In this way, after receiving the second information, the second device can receive the first information according to the frequency resource configuration and/or time domain resource configuration of the first information.

The embodiment of the present application provides a subcarrier modulation method for backscatter communication, as shown in FIG10, including:

Step 201: The first device sends first information to the second device, where the first information includes a subcarrier of a first signal. Modulation type, the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, and the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode, indicating that the reverse scattering frequency band includes Q subcarriers, and Q is less than N;

Step 202: The first device receives a backscatter signal sent by the second device, where the backscatter signal is obtained by performing subcarrier modulation on the first signal;

Step 203: The first device demodulates the backscattered signal according to the first information;

Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol.

In an embodiment of the present application, a first device sends first information to a second device, the first information including a subcarrier modulation type of a first signal, the subcarrier modulation type including dual-frequency modulation and/or single-frequency modulation, the subcarrier modulation type of the dual-frequency modulation including: a first modulation mode, indicating that the reverse scattered frequency band includes Q subcarriers, Q is less than N; when the second device performs single-frequency modulation, the single-frequency modulation uses a clock to modulate the subcarrier, and there is no need to use two clocks at the same time to achieve frequency offset, thereby reducing the requirements for the crystal oscillator accuracy of the second device, or reducing the hardware complexity of the second device; when the second device performs dual-frequency modulation, the reverse scattered frequency band may include Q subcarriers, and there are empty subcarriers in the reverse scattered frequency band. The introduction of empty subcarriers can solve the problem of frequency deviation error caused by the stability of the crystal oscillator, which further causes interference between subcarriers.

The first device is selected from a base station, a reader, a relay node and a terminal, and the second device is selected from a tag and a terminal;

In some embodiments, the first device is a base station, a reader or a relay, and the second device is a tag; or

The first device is a terminal and the second device is a tag; or

The first device is a relay or a base station, and the second device is a terminal.

The label includes at least one of the following:

Passive tags, without energy storage capacitors and/or batteries, rely on environmental signals for energy and communication, do not have carrier generation capabilities, and have the lowest power consumption;

Semi-passive tags have energy storage capacitors and/or batteries, rely on environmental signals for energy storage and communication, and optionally have PA/low noise amplifier (LNA) or other active devices, but do not have carrier generation capabilities and have the second highest power consumption;

Active tags have energy storage capacitors and/or batteries, rely on non-RF signals for power supply, have carrier generation capabilities, consume the most power, and optionally have a PA/low noise amplifier.

Wherein, the dual-frequency modulation uses two clock frequencies to modulate the subcarrier simultaneously;

The single frequency modulation uses a clock frequency to modulate the subcarrier.

When the second device adopts dual-frequency modulation, the second device simultaneously realizes subcarrier modulation through two frequency offsets, realizes subcarrier modulation through different frequency offsets, and is insensitive to the synchronization error of the transmitting and receiving ends; when the second device adopts single-frequency modulation, the second device realizes subcarrier modulation through one frequency offset, which can reduce the hardware requirements.

In this embodiment, the first signal may be a carrier signal, wherein the carrier signal is divided into an energy supply carrier signal and a communication carrier signal, or a carrier signal integrating energy supply and communication. The energy supply carrier signal is mainly used for energy storage and/or modulation of the second device, while the communication carrier signal is mainly a carrier for data bit transmission of the second device. The communication carrier signal may also be a carrier signal carrying information, such as a carrier signal based on OOK modulation and/or BPSK modulation, and the carrier signal may be a single frequency continuous wave, a frequency modulated continuous wave, OFDM, etc.

The first signal may also be a reference signal that does not contain any transmission information, such as the LTE/NR synchronization and reference signals in the related technology, including synchronization signals and physical broadcast channels (SSBs), channel state information reference signals (CSI-RSs), demodulation reference signals, etc.

In some embodiments, the method further comprises any of the following:

The first device sends the first signal to the second device;

The first device sends parameter configuration information of the first signal to a third device, and the third device generates the first signal according to the parameter configuration information and sends it to the second device.

The parameter configuration information of the first signal includes at least one of the following:

Signal type, the signal type includes at least one of the following: a radio frequency signal for energy storage; a radio frequency signal for communication; a radio frequency signal for demodulation; a radio frequency signal for energy storage and modulation;

Time domain resources;

Frequency domain resources;

Bandwidth information;

Waveform type;

Guard interval;

Signal power.

In some embodiments, the first device sending the first information to the second device includes any of the following:

The first device configures the first information and directly sends the first information to the second device;

The first device configures the first information, and forwards the first information to the second device via the third device;

The first device directly sends the first information to the second device, where the first information is a third-party device configuration.

This embodiment is applicable to a single-base architecture and a dual-base architecture. The single-base architecture refers to that the sender of the first signal and the receiver of the backscattered signal are both the first device. When the receiver of the backscattered signal is a device different from the first device, it is a dual-base architecture, and the device is referred to as the third device here.

In some embodiments, under a single-base architecture, the first device may configure the first information and send the configured first information to the second device; or, the first device may configure the first information and send the configured first information to the second device, and the fourth device may send the first signal to the second device, wherein the fourth device is controlled by the first device and is responsible for sending the first signal to the second device; or, a third-party device may configure the first information, and the third-party device may send the first information to the first device and the second device, and the first device may send the first signal to the second device.

In some embodiments, in a dual-base architecture, the first device may configure the first information and the parameter configuration information of the first signal, the first device may send the first information to the second device, and the first device may send the parameter configuration information of the first signal to the third device. information, the third device generates the first signal according to the parameter configuration information of the first signal, and the third device sends the first signal to the second device; or, the first device configures the first information, the first device sends the first information to the third device, and the third device forwards the first information to the second device, and the first device sends the first signal to the second device; or, the first device configures the first information, the first device sends the first information to the third device, and the third device forwards the first information to the second device, the fourth device sends the first signal to the second device, and the fourth device is controlled by the first device; or, the third-party device configures the first information, the third-party device sends the first information to the first device, the second device and the third device, and the first device sends the first signal to the second device; or, the third-party device configures the first information, the third-party device sends the first information to the first device, the second device and the third device, the first device sends the parameter configuration information of the first signal to the third device, the third device generates the first signal according to the parameter configuration information of the first signal, and the third device sends the first signal to the second device.

In this embodiment, the first information is used to indicate relevant information in subcarrier modulation, including subcarrier modulation type, and may also include subcarrier modulation information, subcarrier pattern, etc. When the second device has the ability to actively generate subcarriers, the first information should include the subcarrier pattern, or the subcarrier pattern may be predefined by the protocol.

The subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation. Dual-frequency modulation requires two clocks to modulate the subcarrier simultaneously. The subcarrier modulation type of the dual-frequency modulation includes:

The second modulation mode indicates that the reverse scattered frequency band includes N subcarrier patterns, where N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol, that is, "full carrier" modulation, for example, the reverse scattered frequency band includes a new 64 subcarrier pattern;

The first modulation mode indicates that the reverse scattered frequency band includes Q subcarriers, where Q is less than N, that is, "intermittent" modulation. There are empty subcarriers in the reverse scattered frequency band, and the number of empty subcarriers is N-Q. For example, the new subcarrier pattern contains only 63 subcarriers, and there is 1 empty subcarrier in the reverse scattered frequency band. Because there is 1 empty subcarrier, the introduction of an empty subcarrier can solve the problem of frequency deviation error caused by the stability of the crystal oscillator, which further leads to interference between subcarriers.

Single frequency modulation requires only one clock modulation subcarrier. The subcarrier modulation types of the single frequency modulation include:

The third modulation mode indicates that the number of subcarriers that can be modulated by the second device is K*N, where K is a positive integer, that is, "OFDM symbol repetition" modulation. The second device transmits repeated OFDM symbols, such as two OFDM symbols of the same pattern, constituting 128 subcarriers. In this way, the maximum number of bits that can be modulated is 7, and the number of modulated bits of the tag can be increased;

The fourth modulation mode indicates that P bits to be transmitted are modulated to the left or right, where P is a positive integer, that is, "azimuth information" modulation. Modulating to the left or modulating to the right represents 1 bit to be transmitted. For example, modulating to the left represents bit 1, and modulating to the right represents bit 0. In this way, the maximum number of bits that can be modulated is 7, which can increase the number of modulated bits of the tag.

In some embodiments, the subcarrier modulation information includes at least one of the following: subcarrier spacing, frequency offset indication information, time domain resources, and frequency domain resources.

In some embodiments, the frequency deviation indication information includes at least one of the following:

Frequency offset type, indicating whether the frequency offset is an integer multiple or non-integer multiple of the subcarrier spacing; when the frequency offset is an integer multiple of the subcarrier spacing, assuming the subcarrier spacing is MKHz, the frequency offset value should be TM, where T is a positive integer greater than or equal to 0; when the frequency offset is a non-integer multiple of the subcarrier spacing, assuming the subcarrier spacing is MKHz, the frequency offset value should be This is LM, where L is a non-integer greater than or equal to 0;

Frequency offset range. When the subcarrier modulation type is dual-frequency modulation, the dual-frequency modulation corresponds to two frequency offset ranges, and the maximum frequency offset of each frequency offset range is the product of the number of subcarriers N and the subcarrier interval M; when the subcarrier modulation type is single-frequency modulation, the single-frequency modulation corresponds to a frequency offset range, and its maximum frequency offset should be guaranteed not to exceed the center frequency of the backscatter frequency band to avoid the appearance of more empty subcarriers in the backscatter signal, which affects the demodulation performance.

In some embodiments, there is a mapping relationship between the frequency offset range and the bit information to be transmitted by the second device. The mapping relationship is carried in the first information sent by the first device to the second device; or, the mapping relationship is predefined by the protocol; or, the mapping relationship is carried in the first information forwarded by the first device via a third device; or, the mapping relationship is sent by a fourth device to the second device, and the fourth device provides a radio frequency carrier signal for the second device; or, the mapping relationship is sent by a third-party device to the second device.

In some embodiments, the frequency offset is an integer multiple of the subcarrier spacing, and modulation is achieved based on the subcarrier frequency offset, that is, when the frequency offset value is P (P is an integer) subcarrier spacings, the decimal number of the bit information that can be carried is log ₂ P. For example, when the frequency offset value is 8 subcarrier spacings, the decimal number of the bit information to be transmitted by the second device is 3, and the corresponding bits are 011.

In some embodiments, the frequency offset is a non-integer multiple of the subcarrier spacing, and modulation is implemented based on the subcarrier frequency offset, that is, when the frequency offset value is L (L is a non-integer) subcarrier spacings, the decimal number of the bit information that can be carried is log ₂ L, which satisfies the rounding rule. For example, when the frequency offset value is 7.5 subcarrier spacings, the decimal number of the bit information to be transmitted by the second device is approximately 2.9, and the corresponding bits are 011.

In some embodiments, before the first device sends the first information to the second device, the method further includes:

The first device receives its own capability information reported by the second device, so that the first device can learn the capability information of the second device, and then configure the first information according to the capability information of the second device, wherein the capability information includes at least one of the following:

Device type, indicating whether it has carrier generation capability. Devices with carrier generation capability are active devices, while devices without carrier generation capability are passive or semi-passive devices.

Analog filter parameters, including passband bandwidth, center frequency and cutoff frequency, and stopband suppression;

Frequency deviation capability parameters, including first level duration, first level switching period, frequency modulation capability of the varactor diode, and other hardware capabilities related to the frequency modulation capability;

Oscillator capability parameters, including crystal frequency, for example, a reference clock source of 14.318 MHz; and clock frequency, for example, frequency shift capability corresponding to the number of subcarriers of 2, 4, 8, 16, or 32;

The number and value of load impedance;

Power amplifier PA parameters;

Rectification parameters of the rectifier.

In some embodiments, the method further comprises:

The first device sends second information to the second device, where the second information includes at least one of the following:

The coding indication information includes FM0, i.e., bi-phase interval code coding; and Miller, i.e., Miller code;

Modulation indication information, such as whether the subcarrier modulation used is subcarrier shift keying SSK;

The frequency resource configuration of the first information includes a subband, a resource unit (resource block/resource element, etc.);

The time domain resource configuration of the first information.

In this way, after receiving the second information, the second device can receive the first information according to the frequency resource configuration and/or time domain resource configuration of the first information.

The technical solution of the present application is further introduced below in conjunction with the accompanying drawings and specific embodiments.

In a specific embodiment, the second device receives the first information and the first signal sent by the first device, the second device performs subcarrier modulation based on the first information and the first signal, and sends a backscattered signal to the first device; the first device receives the backscattered signal and demodulates it based on the first signal and the first information. As shown in FIG11, the first signal is the original OFDM symbol. According to the first information, the second device (such as a tag) encodes in an FM0 code, and the modulation type is an "intermittent" modulation of dual-frequency modulation in subcarrier modulation, that is, there are empty subcarriers in the backscattered frequency band.

Taking the tag bit to be transmitted as 000010 as an example, its decimal value is 2; based on this value, the tag uses the serial frequency shift technology to shift the OFDM symbol by 2 and 66+1 subcarriers respectively, in which there is an empty subcarrier; the subcarrier pattern on the reverse scattered frequency band is the result of the cyclic shift of the original symbol subcarrier pattern, with a total of 63 subcarriers. Since two frequency deviations need to be achieved at the same time, and there are empty subcarriers in the reverse scattered frequency band, it is called "intermittent" modulation of double-spelling modulation. Similarly, the decimal value of the bit "000000" is 0, and the frequency deviations are 0 subcarriers and 64+1 subcarriers respectively; the decimal value of the bit "000001" is 1, and the frequency deviations are 1 subcarrier and 65+1 subcarrier respectively; the bit "10" is as mentioned above; the decimal value of the bit "000011" is 3, and the frequency deviations are 3 subcarriers and 67+1 subcarriers respectively.

As shown in Figure 12, after the first device (such as a reader) receives the backscatter signal, it decodes the backscatter signal, correlates the original OFDM symbol and the decoded backscatter signal, and obtains the relative position of the correlation peak (measured by the frequency difference Δf) to complete the demodulation of the tag data. After the first device receives the backscattered subcarrier, it performs a correlation operation with the original subcarrier to obtain a correlation peak with a smaller peak value; the backscatter subcarrier is cyclically shifted, and the subcarrier interval corresponding to the shifted subcarrier (that is, the frequency deviation Fs) represents a different frequency difference. When the cyclically shifted subcarrier is consistent with the original subcarrier, a correlation peak with the strongest peak value can be obtained. The corresponding decision process is as follows:

If the frequencies of the two correlation peaks differ by The judgment is "000000";

If the frequencies of the two correlation peaks differ by The judgment is "000001";

If the frequencies of the two correlation peaks differ by The judgment is "000010";

If the frequencies of the two correlation peaks differ by The judgment is "000011";

It is worth noting that since the first information in the scheme given in this embodiment indicates an "intermittent" modulation mode, there are empty subcarriers in the backscatter signal. After the first device receives the backscatter signal, if it directly performs correlation demodulation, the second peak (i.e., the corresponding tag data part) may drop and cannot be demodulated correctly. An optional method is that since the backscatter symbol has 0, the first device first uses the original OFDM symbol The position of the empty subcarrier is found through matrix operation with the backscattered symbol, and then the position of the 0 subcarrier is filled according to the original subcarrier pattern for subsequent correlation operation.

In another specific embodiment, the subcarrier modulation type is single frequency modulation. The first device repeatedly sends OFDM symbols. In a specific example, the first device configures the repeated OFDM symbols as the first signal according to the capability information of the second device, and the number of subcarriers is expanded. The second device can realize subcarrier modulation through a frequency deviation, and send the backscattered signal to the first device to complete the relevant demodulation.

In this embodiment, the second device receives the first information and the first signal sent by the first device, wherein the first information indicates that the modulation type of the second device is "OFDM symbol repetition" modulation in single frequency modulation of subcarrier modulation, the first signal is an OFDM repetition symbol, and the number of subcarriers is expanded.

The subcarrier modulation is modulated according to the mapping relationship between the bit information to be transmitted by the second device and the subcarrier frequency deviation range. Since the center frequency and bandwidth of the reverse scatter band are determined, when configuring the mapping relationship of the subcarrier modulation, it is necessary to avoid the situation where there are too many "empty subcarriers" in the reverse scatter band.

The second device performs subcarrier modulation based on the first information and the first signal, and sends a backscattered signal to the first device; the first device receives the backscattered signal, and performs correlation demodulation based on the first signal and the first information.

As shown in FIG13 , the first signal is two repeated OFDM symbols with 128 subcarriers, and the first information is a single-frequency modulated "OFDM symbol repetition" modulation. The reverse scatter band is fixed, and its bandwidth is equal to the SCS of 64 subcarriers. Whether the reverse scatter band is located on the left, right or middle of the original band depends on the center frequency of the analog filter. Assuming that the reverse scatter band is located in the middle of the original band, the number of modulated bits is at most 6 bits, which avoids the appearance of too many empty subcarriers and affects the demodulation of the receiving end.

In another specific embodiment, the first device configures an OFDM symbol as the first signal according to the capability information of the second device. The second device can implement subcarrier modulation through a frequency deviation, and send the backscattered signal to the first device to complete the relevant demodulation. In this embodiment, when modulating through a switch/analog device, the frequency deviation has two directions, so one bit to be transmitted in the second device is modulated according to the left/right frequency deviation (positive/negative frequency deviation value).

The second device receives the first information and the first signal sent by the first device, wherein the first information indicates that the modulation type of the second device is "azimuth information type" modulation in the single frequency modulation of subcarrier modulation, and one bit to be transmitted in the second device is modulated according to the left/right frequency deviation (positive/negative frequency deviation value).

The subcarrier modulation is modulated according to the mapping relationship between the bit information to be transmitted by the second device and the subcarrier frequency deviation. Since the center frequency point and bandwidth of the reverse scatter band are determined, when configuring the mapping relationship of the subcarrier modulation, since 1 bit of information represents the left/right frequency deviation, it is necessary to avoid the situation where too many "empty subcarriers" appear in the reverse scatter band and modulate more bit information. Therefore, the center frequency point of the reverse scatter band should be located in the middle of the original frequency band as much as possible.

The second device performs subcarrier modulation based on the first information and the first signal, and sends a backscattered signal to the first device; the first device receives the backscattered signal, and performs correlation demodulation based on the first signal and the first information.

As shown in FIG14 , the first signal is an original OFDM symbol with 64 subcarriers, and the first information is a single-frequency modulation "azimuth information type" modulation. The reverse scatter band is fixed, and its bandwidth is equal to the SCS of 32 subcarriers. The reverse scatter band is located in the middle of the original band. Assuming that the reverse scatter band is located in the middle of the original band, it can be The maximum number of modulated bits is 5+1 bits, which avoids the occurrence of too many empty subcarriers and affects the demodulation at the receiving end.

In the above embodiment, the first device sends the first signal to the second device. In another specific embodiment, the second device has a carrier generation capability. In this embodiment, the signal type of the first signal is mainly an RF signal for power supply and an RF signal for demodulation. Since the second device has a carrier generation capability, the signal type of the first signal does not consider the RF signal for modulation.

In a specific example, the second device only receives the first information, actively generates a carrier signal, and performs subcarrier modulation based on the first information;

In another specific example, the second device receives the first information and the first signal, wherein the signal type of the first signal is an RF signal for demodulation. At the same time, the second device actively generates a carrier signal (second signal) and performs polarization modulation based on the first information;

In another specific example, the second device receives the first information and the first signal, wherein the signal type of the first signal is an RF signal for power supply. At the same time, the second device actively generates a carrier signal and performs polarization modulation based on the first information.

The subcarrier modulation method for backscatter communication provided in the embodiment of the present application can be performed by a subcarrier modulation device for backscatter communication. In the embodiment of the present application, the subcarrier modulation method for backscatter communication performed by the subcarrier modulation device for backscatter communication is taken as an example to illustrate the subcarrier modulation device for backscatter communication provided in the embodiment of the present application.

The embodiment of the present application provides a subcarrier modulation device for backscatter communication, which is applied to a second device, including:

A first receiving module is configured to receive first information sent by a first device, wherein the first information includes a subcarrier modulation type of a first signal, wherein the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, and the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode indicating that a reverse scattering frequency band includes Q subcarriers, where Q is less than N;

A modulation module, configured to perform subcarrier modulation on the first signal according to the first information to obtain a backscattered signal;

A first sending module, configured to send the backscattered signal to the first device;

Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol.

In some embodiments, the dual-frequency modulation uses two clock frequencies to simultaneously modulate a subcarrier;

The single frequency modulation uses a clock frequency to modulate the subcarrier.

In some embodiments, the first information further includes at least one of the following: subcarrier modulation information and subcarrier pattern of the first signal.

In some embodiments, the subcarrier modulation type of the single frequency modulation includes:

A third modulation mode, indicating that the number of subcarriers modulatable by the second device is K*N, where K is a positive integer;

The fourth modulation mode indicates modulating P bits to be transmitted to the left or right, where P is a positive integer.

In some embodiments, the first receiving module is used to perform any of the following:

Receiving the first information configured and sent by the first device;

receiving the first information sent by the first device, where the first information is a third-party device configuration;

The first information forwarded by the first device via a third device is received.

In some embodiments, the subcarrier modulation information includes at least one of the following: subcarrier spacing, frequency deviation indication information, Time domain resources and frequency domain resources.

In some embodiments, the frequency deviation indication information includes at least one of the following:

Frequency offset type, indicating whether the frequency offset is an integer or non-integer multiple of the subcarrier spacing;

Frequency offset range.

In some embodiments, when the subcarrier modulation type is dual-frequency modulation, the dual-frequency modulation corresponds to two frequency offset ranges, and the maximum frequency deviation of each frequency offset range is the product of the number of subcarriers N and the subcarrier interval M;

When the subcarrier modulation type is single-frequency modulation, the single-frequency modulation corresponds to a frequency offset range.

In some embodiments, there is a mapping relationship between the frequency offset range and the bit information to be transmitted by the second device.

In some embodiments, the mapping relationship is carried in first information sent by the first device to the second device; or

The mapping relationship is predefined by the protocol; or

The mapping relationship is carried in the first information forwarded by the first device via a third device; or

The mapping relationship is that the fourth device sends the signal to the second device, and the fourth device provides a radio frequency carrier signal to the second device; or

The mapping relationship is sent by a third-party device to the second device.

In some embodiments, the first sending module is further configured to report its own capability information to the first device, where the capability information includes at least one of the following:

Device type, indicating whether it has carrier generation capability;

Analog filter parameters;

Frequency deviation capability parameters;

Oscillator capability parameters;

The number and value of load impedance;

Power amplifier PA parameters;

Rectification parameters of the rectifier.

In some embodiments, the first receiving module is further used to receive second information sent by the first device, where the second information includes at least one of the following: coding indication information, modulation indication information, frequency resource configuration of the first information, and time domain resource configuration of the first information.

In some embodiments, the first receiving module is used to perform any of the following:

receiving the first signal sent by a fourth device;

receiving the first signal sent by the first device;

The first signal sent by the third device is received, where the first signal is generated by the third device according to parameter configuration information configured by the first device.

In some embodiments, the parameter configuration information of the first signal includes at least one of the following:

signal type;

Time domain resources;

Frequency domain resources;

Bandwidth information;

Waveform type;

Guard interval;

Signal power.

In some embodiments, the signal type includes at least one of the following:

RF signals for energy storage;

RF signals for communication

RF signal for demodulation

RF signal for energy storage and modulation.

The embodiment of the present application provides a subcarrier modulation device for backscatter communication, which is applied to a first device, including:

A second sending module is used to send first information to a second device, where the first information includes a subcarrier modulation type of the first signal, where the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, where the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode, indicating that the reverse scattering frequency band includes Q subcarriers, where Q is less than N;

A second receiving module, used to receive a backscattered signal sent by the second device, where the backscattered signal is obtained by subcarrier modulating the first signal;

A demodulation module, configured to demodulate the backscattered signal according to the first information;

Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol.

In some embodiments, the dual-frequency modulation uses two clock frequencies to simultaneously modulate a subcarrier;

The single frequency modulation uses a clock frequency to modulate the subcarrier.

In some embodiments, the first information further includes at least one of the following: subcarrier modulation information and subcarrier pattern of the first signal.

In some embodiments, the subcarrier modulation type of the single frequency modulation includes:

A third modulation mode, indicating that the number of subcarriers modulatable by the second device is K*N, where K is a positive integer;

The fourth modulation mode indicates modulating P bits to be transmitted to the left or right, where P is a positive integer.

In some embodiments, the second sending module is configured to perform any of the following:

configuring the first information, and directly sending the first information to the second device;

configuring the first information, and forwarding the first information to the second device via the third device;

The first information is directly sent to the second device, where the first information is a third-party device configuration.

In some embodiments, the subcarrier modulation information includes at least one of the following: subcarrier spacing, frequency offset indication information, time domain resources, and frequency domain resources.

In some embodiments, the frequency deviation indication information includes at least one of the following:

Frequency offset type, indicating whether the frequency offset is an integer or non-integer multiple of the subcarrier spacing;

Frequency offset range.

In some embodiments, when the subcarrier modulation type is dual-frequency modulation, the dual-frequency modulation corresponds to two frequency deviations. The maximum frequency deviation of each frequency offset range is the product of the number of subcarriers N and the subcarrier spacing M;

When the subcarrier modulation type is single-frequency modulation, the single-frequency modulation corresponds to a frequency offset range.

In some embodiments, there is a mapping relationship between the frequency offset range and the bit information to be transmitted by the second device.

In some embodiments, the mapping relationship is carried in first information sent by the first device to the second device; or

The mapping relationship is predefined by the protocol; or

The mapping relationship is carried in the first information forwarded by the first device via a third device; or

The mapping relationship is that the fourth device sends the signal to the second device, and the fourth device provides a radio frequency carrier signal to the second device; or

The mapping relationship is sent by a third-party device to the second device.

In some embodiments, the second receiving module is used to receive capability information of the second device reported by the second device, where the capability information includes at least one of the following:

Device type, indicating whether it has carrier generation capability;

Analog filter parameters;

Frequency deviation capability parameters;

Oscillator capability parameters;

The number and value of load impedance;

Power amplifier PA parameters;

Rectification parameters of the rectifier.

In some embodiments, the second sending module is further used to send second information to the second device, and the second information includes at least one of the following: coding indication information, modulation indication information, frequency resource configuration of the first information, and time domain resource configuration of the first information.

In some embodiments, the second sending module is used to perform any of the following:

sending the first signal to the second device;

The parameter configuration information of the first signal is sent to a third device, and the third device generates the first signal according to the parameter configuration information and sends the first signal to the second device.

In some embodiments, the parameter configuration information of the first signal includes at least one of the following:

signal type;

Time domain resources;

Frequency domain resources;

Bandwidth information;

Waveform type;

Guard interval;

Signal power.

In some embodiments, the signal type includes at least one of the following:

RF signals for energy storage;

RF signals for communication

RF signal for demodulation

RF signal for energy storage and modulation.

The subcarrier modulation device for backscatter communication in the embodiment of the present application can be an electronic device, such as an electronic device with an operating system, or a component in an electronic device, such as an integrated circuit or a chip. The electronic device can be a terminal, or it can be other devices other than a terminal. Exemplarily, the terminal can include but is not limited to the types of terminal 11 listed above, and other devices can be servers, network attached storage (NAS), etc., which are not specifically limited in the embodiment of the present application.

The subcarrier modulation device for backscatter communication provided in the embodiment of the present application can implement the various processes implemented in the method embodiments of Figures 9 to 14 and achieve the same technical effect. To avoid repetition, it will not be repeated here.

Optionally, as shown in FIG15, an embodiment of the present application further provides a communication device 600, including a processor 601 and a memory 602, wherein the memory 602 stores a program or instruction that can be run on the processor 601. For example, when the communication device 600 is a network side device, the program or instruction is executed by the processor 601 to implement the various steps of the above-mentioned subcarrier modulation method embodiment for backscatter communication, and can achieve the same technical effect. When the communication device 600 is a terminal, the program or instruction is executed by the processor 601 to implement the various steps of the above-mentioned subcarrier modulation method embodiment for backscatter communication, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

The embodiment of the present application further provides a second device, including a processor and a communication interface, wherein the communication interface is used to receive first information sent by a first device, the first information includes a subcarrier modulation type of a first signal, the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, and the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode, indicating that the reverse scattering frequency band includes Q subcarriers, and Q is less than N; the processor is used to perform subcarrier modulation on the first signal according to the first information to obtain a backscattering signal; the communication interface is used to send the backscattering signal to the first device;

Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol.

An embodiment of the present application also provides a second device, which communication device includes a processor and a memory, wherein the memory stores a program or instruction that can be executed on the processor, and when the program or instruction is executed by the processor, the steps of the method described in the first aspect are implemented.

An embodiment of the present application also provides a first device, including a processor and a communication interface, wherein the communication interface is used to send first information to a second device, the first information including a subcarrier modulation type of a first signal, the subcarrier modulation type including dual-frequency modulation and/or single-frequency modulation, and the subcarrier modulation type of the dual-frequency modulation including: a first modulation mode, indicating that the reverse scatter frequency band includes Q subcarriers, Q is less than N; send first information to a second device, the first information including a subcarrier modulation type of the first signal, the subcarrier modulation type including dual-frequency modulation and/or single-frequency modulation, and the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode, indicating that the reverse scatter frequency band includes Q subcarriers, Q is less than N; receive a backscatter signal sent by the second device, the backscatter signal being obtained by subcarrier modulating the first signal; the processor is used to modulate the backscatter signal according to the first information The signal is demodulated;

Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol.

An embodiment of the present application also provides a first device, which communication device includes a processor and a memory, wherein the memory stores a program or instruction that can be executed on the processor, and when the program or instruction is executed by the processor, the steps of the method described in the third aspect are implemented.

The embodiment of the present application also provides a terminal, including a processor and a communication interface, and each implementation process and implementation method of the above method embodiment can be applied to the terminal embodiment and can achieve the same technical effect. Specifically, Figure 16 is a schematic diagram of the hardware structure of a terminal implementing the embodiment of the present application.

The terminal 700 includes but is not limited to: a radio frequency unit 701, a network module 702, an audio output unit 703, an input unit 704, a sensor 705, a display unit 706, a user input unit 707, an interface unit 708, a memory 709 and at least some of the components of a processor 710.

Those skilled in the art will appreciate that the terminal 700 may also include a power source (such as a battery) for supplying power to each component, and the power source may be logically connected to the processor 710 through a power management system, so as to implement functions such as managing charging, discharging, and power consumption management through the power management system. The terminal structure shown in FIG16 does not constitute a limitation on the terminal, and the terminal may include more or fewer components than shown in the figure, or combine certain components, or arrange components differently, which will not be described in detail here.

It should be understood that in the embodiment of the present application, the input unit 704 may include a graphics processing unit (GPU) 7041 and a microphone 7042, and the graphics processor 7041 processes the image data of a static picture or video obtained by an image capture device (such as a camera) in a video capture mode or an image capture mode. The display unit 706 may include a display panel 7061, and the display panel 7061 may be configured in the form of a liquid crystal display, an organic light emitting diode, etc. The user input unit 707 includes a touch panel 7071 and at least one of other input devices 7072. The touch panel 7071 is also called a touch screen. The touch panel 7071 may include two parts: a touch detection device and a touch controller. Other input devices 7072 may include, but are not limited to, a physical keyboard, function keys (such as a volume control key, a switch key, etc.), a trackball, a mouse, and a joystick, which will not be repeated here.

In the embodiment of the present application, after receiving downlink data from the network side device, the RF unit 701 can transmit the data to the processor 710 for processing; in addition, the RF unit 701 can send uplink data to the network side device. Generally, the RF unit 701 includes but is not limited to an antenna, an amplifier, a transceiver, a coupler, a low noise amplifier, a duplexer, etc.

The memory 709 can be used to store software programs or instructions and various data. The memory 709 may mainly include a first storage area for storing programs or instructions and a second storage area for storing data, wherein the first storage area may store an operating system, an application program or instruction required for at least one function (such as a sound playback function, an image playback function, etc.), etc. In addition, the memory 709 may include a volatile memory or a non-volatile memory, or the memory 709 may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), a static random access memory (SRAM), a dynamic random access memory (DRAM), a synchronous dynamic random access memory (DRAM), or a volatile memory. The memory 709 in the embodiment of the present application includes but is not limited to these and any other suitable types of memory.

The processor 710 may include one or more processing units; optionally, the processor 710 integrates an application processor and a modem processor, wherein the application processor mainly processes operations related to an operating system, a user interface, and application programs, and the modem processor mainly processes wireless communication signals, such as a baseband processor. It is understandable that the modem processor may not be integrated into the processor 710.

The embodiment of the present application also provides a network side device, including a processor and a communication interface. Each implementation process and implementation method of the above method embodiment can be applied to the network side device embodiment, and can achieve the same technical effect. As shown in Figure 17, the network side device 800 includes: an antenna 81, a radio frequency device 82, a baseband device 83, a processor 84 and a memory 85. The antenna 81 is connected to the radio frequency device 82. In the uplink direction, the radio frequency device 82 receives information through the antenna 81 and sends the received information to the baseband device 83 for processing. In the downlink direction, the baseband device 83 processes the information to be sent and sends it to the radio frequency device 82. The radio frequency device 82 processes the received information and sends it out through the antenna 81.

The method executed by the network-side device in the above embodiment may be implemented in the baseband device 83, which includes a baseband processor.

The baseband device 83 may include, for example, at least one baseband board, on which multiple chips are arranged, as shown in Figure 17, one of which is, for example, a baseband processor, which is connected to the memory 85 through a bus interface to call the program in the memory 85 to execute the network device operations shown in the above method embodiment.

The network side device may also include a network interface 86, which is, for example, a common public radio interface (CPRI).

Specifically, the network side device 800 of the embodiment of the present application also includes: instructions or programs stored in the memory 85 and executable on the processor 84. The processor 84 calls the instructions or programs in the memory 85 to execute the subcarrier modulation method for backscatter communication as described above and achieve the same technical effect. To avoid repetition, it will not be repeated here.

An embodiment of the present application also provides a communication system, including: a first device and a second device, wherein the second device can be used to execute the steps of the subcarrier modulation method for backscatter communication as described in the first aspect, and the first device can be used to execute the steps of the subcarrier modulation method for backscatter communication as described in the third aspect.

An embodiment of the present application also provides a readable storage medium, which may be volatile or non-volatile. A program or instruction is stored on the readable storage medium. When the program or instruction is executed by a processor, each process of the above-mentioned subcarrier modulation method embodiment for backscatter communication is implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

The processor is the processor in the terminal described in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a computer read-only memory ROM, a random access memory RAM, a magnetic disk or an optical disk. wait.

An embodiment of the present application further provides a chip, which includes a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run programs or instructions to implement the various processes of the above-mentioned subcarrier modulation method embodiment for backscatter communication, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

It should be understood that the chip mentioned in the embodiments of the present application can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

An embodiment of the present application further provides a computer program/program product, which is stored in a storage medium. The computer program/program product is executed by at least one processor to implement the various processes of the above-mentioned subcarrier modulation method embodiment for backscatter communication, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

It should be noted that, in this article, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the relevant technology, can be embodied in the form of a computer software product, which is stored in a storage medium (such as ROM/RAM, magnetic disk, optical disk), and includes a number of instructions for a terminal (which can be a mobile phone, computer, server, air conditioner, or network equipment, etc.) to execute the methods described in each embodiment of the present application.

The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims (32)

A subcarrier modulation method for backscatter communication, comprising: The second device receives first information sent by the first device, where the first information includes a subcarrier modulation type of the first signal, where the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, where the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode indicating that the reverse scattering frequency band includes Q subcarriers, where Q is less than N; The second device performs subcarrier modulation on the first signal according to the first information to obtain a backscattered signal; The second device sends the backscatter signal to the first device; Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol. The method according to claim 1, wherein the first information further includes at least one of the following: subcarrier modulation information and subcarrier pattern of the first signal. The method according to claim 1, wherein The subcarrier modulation types of the single frequency modulation include: A third modulation mode, indicating that the number of subcarriers modulatable by the second device is K*N, where K is a positive integer; The fourth modulation mode indicates modulating P bits to be transmitted to the left or right, where P is a positive integer. The method according to claim 1, wherein the receiving, by the second device, of the first information sent by the first device comprises any one of the following: The second device receives the first information configured and sent by the first device; The second device receives the first information sent by the first device, where the first information is a third-party device configuration; The second device receives the first information forwarded by the first device via the third device. The method according to claim 2, wherein The subcarrier modulation information includes at least one of the following: subcarrier spacing, frequency offset indication information, time domain resources, and frequency domain resources. The method according to claim 5, wherein the frequency deviation indication information includes at least one of the following: Frequency offset type, indicating whether the frequency offset is an integer or non-integer multiple of the subcarrier spacing; Frequency offset range. The method according to claim 6, wherein When the subcarrier modulation type is dual-frequency modulation, the dual-frequency modulation corresponds to two frequency offset ranges, and the maximum frequency deviation of each frequency offset range is the product of the number of subcarriers N and the subcarrier interval M; When the subcarrier modulation type is single-frequency modulation, the single-frequency modulation corresponds to a frequency offset range. The method according to claim 6, wherein there is a mapping relationship between the frequency offset range and the bit information to be transmitted by the second device. The method according to claim 8, wherein The mapping relationship is carried in the first information sent by the first device to the second device; or The mapping relationship is predefined by the protocol; or The mapping relationship is carried in the first information forwarded by the first device via a third device; or The mapping relationship is that the fourth device sends the signal to the second device, and the fourth device provides a radio frequency carrier signal to the second device; or The mapping relationship is sent by a third-party device to the second device. The method according to claim 1, wherein before the second device receives the first information sent by the first device, the method further comprises: The second device reports its own capability information to the first device, where the capability information includes at least one of the following: Device type, indicating whether it has carrier generation capability; Analog filter parameters; Frequency deviation capability parameters; Oscillator capability parameters; The number and value of load impedance; Power amplifier PA parameters; Rectification parameters of the rectifier. The method according to claim 1, further comprising: The second device receives second information sent by the first device, where the second information includes at least one of the following: coding indication information, modulation indication information, frequency resource configuration of the first information, and time domain resource configuration of the first information. The method according to claim 1 or 4, further comprising any of the following: The second device receives the first signal sent by the fourth device; The second device receives the first signal sent by the first device; The second device receives the first signal sent by the third device, where the first signal is generated by the third device according to parameter configuration information configured by the first device. The method according to claim 12, wherein the parameter configuration information of the first signal includes at least one of the following: signal type; Time domain resources; Frequency domain resources; Bandwidth information; Waveform type; Guard interval; Signal power. The method according to claim 13, wherein the signal type comprises at least one of the following: RF signals for energy storage; RF signals for communication RF signal for demodulation RF signal for energy storage and modulation. A subcarrier modulation method for backscatter communication, comprising: The first device sends first information to the second device, where the first information includes a subcarrier modulation type of the first signal, where the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, where the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode, indicating that the reverse scattering frequency band includes Q subcarriers, where Q is less than N; The first device receives a backscatter signal sent by the second device, where the backscatter signal is obtained by performing subcarrier modulation on the first signal; The first device demodulates the backscattered signal according to the first information; Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol. The method according to claim 15, wherein the first information further includes at least one of the following: subcarrier modulation information and subcarrier pattern of the first signal. The method according to claim 15, wherein The subcarrier modulation types of the single frequency modulation include: A third modulation mode, indicating that the number of subcarriers modulatable by the second device is K*N, where K is a positive integer; The fourth modulation mode indicates modulating P bits to be transmitted to the left or right, where P is a positive integer. The method according to claim 15, wherein the first device sending the first information to the second device comprises any one of the following: The first device configures the first information and directly sends the first information to the second device; The first device configures the first information, and forwards the first information to the second device via a third device; The first device directly sends the first information to the second device, where the first information is a third-party device configuration. The method according to claim 16, wherein the subcarrier modulation information includes at least one of the following: subcarrier spacing, frequency offset indication information, time domain resources, and frequency domain resources. The method according to claim 19, wherein the frequency deviation indication information includes at least one of the following: Frequency offset type, indicating whether the frequency offset is an integer or non-integer multiple of the subcarrier spacing; Frequency offset range. The method according to claim 20, wherein When the subcarrier modulation type is dual-frequency modulation, the dual-frequency modulation corresponds to two frequency offset ranges, and the maximum frequency deviation of each frequency offset range is the product of the number of subcarriers N and the subcarrier interval M; When the subcarrier modulation type is single-frequency modulation, the single-frequency modulation corresponds to a frequency offset range. The method according to claim 20, wherein there is a mapping relationship between the frequency offset range and the bit information to be transmitted by the second device. The method according to claim 22, wherein The mapping relationship is carried in the first information sent by the first device to the second device; or The mapping relationship is predefined by the protocol; or The mapping relationship is carried in the first information forwarded by the first device via a third device; or The mapping relationship is that the fourth device sends the signal to the second device, and the fourth device provides a radio frequency carrier signal to the second device; or The mapping relationship is sent by a third-party device to the second device. The method according to claim 15, wherein before the first device sends the first information to the second device, the method further comprises: The first device receives capability information of the second device reported by the second device, where the capability information includes at least one of the following: Device type, indicating whether it has carrier generation capability; Analog filter parameters; Frequency deviation capability parameters; Oscillator capability parameters; The number and value of load impedance; Power amplifier PA parameters; Rectification parameters of the rectifier. The method according to claim 15, further comprising: The first device sends second information to the second device, where the second information includes at least one of the following: coding indication information, modulation indication information, frequency resource configuration of the first information, and time domain resource configuration of the first information. The method according to claim 15, further comprising any of the following: The first device sends the first signal to the second device; The first device sends parameter configuration information of the first signal to a third device, and the third device generates the first signal according to the parameter configuration information and sends it to the second device. The method according to claim 26, wherein the parameter configuration information of the first signal includes at least one of the following: signal type; Time domain resources; Frequency domain resources; Bandwidth information; Waveform type; Guard interval; Signal power. The method according to claim 27, wherein the signal type includes at least one of the following: RF signals for energy storage; RF signals for communication RF signal for demodulation RF signal for energy storage and modulation. A subcarrier modulation device for backscatter communication, comprising: A first receiving module is configured to receive first information sent by a first device, wherein the first information includes a subcarrier modulation type of a first signal, wherein the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, and the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode indicating that a reverse scattering frequency band includes Q subcarriers, where Q is less than N; A modulation module, configured to perform subcarrier modulation on the first signal according to the first information to obtain a backscattered signal; A first sending module, configured to send the backscattered signal to the first device; Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol. A subcarrier modulation device for backscatter communication, comprising: A second sending module is used to send first information to a second device, where the first information includes a subcarrier modulation type of the first signal, where the subcarrier modulation type includes dual-frequency modulation and/or single-frequency modulation, where the subcarrier modulation type of the dual-frequency modulation includes: a first modulation mode, indicating that the reverse scattering frequency band includes Q subcarriers, where Q is less than N; A second receiving module, used to receive a backscattered signal sent by the second device, where the backscattered signal is obtained by subcarrier modulating the first signal; A demodulation module, configured to demodulate the backscattered signal according to the first information; Wherein, N is the number of subcarriers included in an orthogonal frequency division multiplexing OFDM symbol. A communication device comprises a processor and a memory, wherein the memory stores a program or instruction that can be run on the processor, and when the program or instruction is executed by the processor, the steps of the subcarrier modulation method for backscatter communication as described in any one of claims 1 to 28 are implemented. A readable storage medium stores a program or instruction, and when the program or instruction is executed by a processor, the steps of the subcarrier modulation method for backscatter communication as described in any one of claims 1-28 are implemented.