Signal transmission method and device, apparatus, and storage medium

Abstract

The application provides a signal transmission method and device, equipment and a storage medium. The method comprises the following steps: a first indication signal is sent to a first ambient Internet of Things (A-IoT) device, the first indication signal is used for instructing the first A-IoT device to perform frequency shift on a first orthogonal frequency division multiplexing (OFDM) signal to obtain a second OFDM signal and send the second OFDM signal, wherein the first indication signal carries at least one of the following: a set of transmission frequency offset parameters; an A-IoT device modulation mode; a subcarrier spacing; and a transmission guard interval. The OFDM signal transmission performance is improved.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a signal transmission method, apparatus, device and storage medium. Background Technology

[0002] Currently, in Internet of Things (IoT) networks, IoT devices are mainly powered by batteries, which have limited lifespans, restricting their deployment and use. Furthermore, the rapid growth of IoT devices and the large-scale deployment drive up maintenance costs. In some cases, maintaining the operation of IoT devices and replacing batteries is challenging. Therefore, a battery-free Ambient IoT (A-IoT) technology has been proposed, which can improve network performance, operate for extended periods without maintenance, and expand application scenarios. A-IoT devices can support environmental power supply and are IoT devices powered by energy harvesting. They have no batteries or limited energy storage capacity (e.g., using capacitors), providing power for communication by harvesting radio waves, light, motion, heat, or any other harvestable energy from the environment. A-IoT features low energy consumption, low cost, and low complexity. The relevant protocols define three types of A-IoT devices: Type 1 (also known as Type A): no energy storage capability, no independent signal generation capability, and transmits signals via backscattering; Type 2: has energy storage capability, including Type 2a (also known as Type B) and Type 2b (also known as Type C). Type 2a: has energy storage capability, no independent signal generation capability, and transmits signals via backscattering; the stored energy can be used to amplify the power of the backscattered signal; Type 2b: has energy storage capability, has independent signal generation capability, and can use radio frequency (RF) devices for signal transmission. The general principle for backscattering is: the reader / writer generates the RF excitation signal, the reflective tag consists of devices that can reflect RF signals, the reader / writer sends the RF signal to the reflective tag, the reflective tag receives the signal from the excitation signal source, and then reflects the RF signal.

[0003] In backscatter communication, A-IoT devices can avoid direct path interference by frequency shifting the incident signal by changing the impedance switching frequency. Type 1 / 2 A-IoT devices can achieve backscatter communication by reflecting the OFDM signal transmitted by the carrier wave (CW) transmitting node (first node). To further improve system capacity, the same first node may serve multiple A-IoT devices. Multiple A-IoT devices may simultaneously reflect the OFDM signal transmitted by the first node, which can easily lead to interference between A-IoT devices, resulting in poor OFDM signal transmission performance. Summary of the Invention

[0004] This application provides a signal transmission method, apparatus, device, and storage medium to solve the problem of poor OFDM signal transmission performance in A-IoT devices.

[0005] This application provides a signal transmission method applied to a first node, the method comprising:

[0006] Send a first indication signal to a first environmental Internet of Things (A-IoT) device, the first indication signal being used to instruct the first A-IoT device to frequency shift a first orthogonal frequency division multiplexing (OFDM) signal to obtain a second OFDM signal and then send the second OFDM signal;

[0007] The first indication signal carries at least one of the following:

[0008] Set of transmission frequency offset parameters;

[0009] A-IoT device modulation method;

[0010] Subcarrier spacing;

[0011] Transmission protection interval.

[0012] In some embodiments, before sending the first indication signal to the first environmental Internet of Things (A-IoT) device, at least one of the following is further included:

[0013] The frequency domain sequence length is determined based on the aforementioned transmission frequency offset parameter set; or

[0014] Obtain the frequency domain sequence length; based on the frequency domain sequence length, determine the transmission frequency offset parameter set.

[0015] In some embodiments, the method further includes:

[0016] Based on the transmission frequency offset parameter set and the frequency domain sequence length, the frequency domain resources used by the first node to receive the second OFDM signal are determined.

[0017] In some embodiments, the frequency domain resources include X subcarriers, where X is a value of 2*N. 1,1max +L+N′; where L is the length of the frequency domain sequence, N 1,1max The maximum frequency offset parameter in the set of transmission frequency offset parameters, where N′ is the number of subcarriers occupied by the first guard interval, and N′ is an integer greater than or equal to 0.

[0018] In some embodiments, before sending the first indication signal to the first environmental Internet of Things (A-IoT) device, the method further includes: determining a frequency domain sequence, wherein the length of the frequency domain sequence is the length of the frequency domain sequence;

[0019] After determining the frequency domain resources for the first node to receive the second OFDM signal based on the transmission frequency offset parameter set and the frequency domain sequence length, the process includes: detecting the second OFDM signal on the frequency domain resources, and demodulating the second OFDM signal based on the frequency domain sequence to obtain the received bit information.

[0020] In some embodiments, the step of demodulating the second OFDM signal based on the frequency domain sequence to obtain the received bit information includes:

[0021] The second OFDM signal is received at a first frequency position relative to the frequency domain sequence by a first frequency offset parameter of subcarriers. The frequency correlation between the frequency domain sequence and the second OFDM signal received at the first frequency position is calculated to obtain a first correlation. The first frequency offset parameter is a parameter in the transmission frequency offset parameter set and is the frequency offset parameter used by the first A-IoT device when sending the first bit.

[0022] The second OFDM signal is received at a second frequency position relative to the frequency domain sequence by a second frequency offset parameter of subcarriers. The frequency correlation between the frequency domain sequence and the second OFDM signal received at the second frequency position is calculated to obtain a second correlation. The second frequency offset parameter is a parameter in the transmission frequency offset parameter set and is the frequency offset parameter used by the first A-IoT device when sending the second bit.

[0023] The bit information is determined based on the first correlation and the second correlation.

[0024] In some embodiments, the total length of the transmission guard interval and the frequency domain sequence length is less than or equal to a target value, or the length of the frequency domain sequence is less than or equal to a target value;

[0025] Wherein, the target value is a first value, or the minimum value between the first value and the second value; the first value is the minimum value of the difference between every two frequency offset parameters in the transmission frequency offset parameter set, and the second value is the minimum frequency offset parameter in the transmission frequency offset parameter set.

[0026] In some embodiments, the frequency offset of the second OFDM signal relative to the first OFDM signal is a positive integer multiple of the subcarrier spacing.

[0027] In some embodiments, the transmission frequency offset parameter set includes a frequency offset parameter corresponding to each of at least one A-IoT device, wherein the at least one A-IoT device includes the first A-IoT device;

[0028] The first indication signal also carries at least one of the following:

[0029] The time corresponding to each of the at least one A-IoT devices is used to instruct the A-IoT device to send the second OFDM signal at that time using the frequency offset parameter corresponding to the A-IoT device.

[0030] This application provides a signal transmission method applied to a first A-IoT device, including:

[0031] Receive the first indication signal sent by the first node;

[0032] Based on the first indication signal, the first OFDM signal is frequency-shifted to obtain the second OFDM signal;

[0033] Send the second OFDM signal to the first node;

[0034] The first indication signal carries at least one of the following:

[0035] Set of transmission frequency offset parameters;

[0036] A-IoT device modulation method;

[0037] Subcarrier spacing;

[0038] Transmission protection interval.

[0039] In some embodiments, the total length of the transmission guard interval and the frequency domain sequence length is less than or equal to a target value, or the length of the frequency domain sequence is less than or equal to a target value;

[0040] Wherein, the target value is a first value, or the minimum value between the first value and the second value; the first value is the minimum value of the difference between every two frequency offset parameters in the transmission frequency offset parameter set, and the second value is the minimum frequency offset parameter in the transmission frequency offset parameter set.

[0041] In some embodiments, the frequency offset of the second OFDM signal relative to the first OFDM is a positive integer multiple of the subcarrier spacing.

[0042] In some embodiments, the transmission frequency offset parameter set includes a frequency offset parameter corresponding to each of at least one A-IoT device, wherein the at least one A-IoT device includes the first A-IoT device;

[0043] The first indication signal also carries at least one of the following:

[0044] The time corresponding to each of the at least one A-IoT devices is used to instruct the A-IoT device to send the second OFDM signal using the frequency offset parameter corresponding to the A-IoT device at that time, and the time corresponding to the first A-IoT device is the first time;

[0045] The step of sending the second OFDM signal to the first node includes: sending the second OFDM signal to the first node at the first time.

[0046] This application provides a communication device, including: a memory, a transceiver, and a processor. The communication device includes a first node, wherein:

[0047] The memory is used to store computer programs; the transceiver is used to send and receive data under the control of the processor; the processor is used to read the computer programs in the memory and perform the following operations:

[0048] Send a first indication signal to the first A-IoT device, the first indication signal being used to instruct the first A-IoT device to frequency shift the first orthogonal frequency division multiplexing (OFDM) signal to obtain a second OFDM signal and then send the second OFDM signal;

[0049] The first indication signal carries at least one of the following:

[0050] Set of transmission frequency offset parameters;

[0051] A-IoT device modulation method;

[0052] Subcarrier spacing;

[0053] Transmission protection interval.

[0054] This application provides a communication device, including: a memory, a transceiver, and a processor. The communication device includes a first AIoT device, wherein:

[0055] The memory is used to store computer programs; the transceiver is used to send and receive data under the control of the processor; the processor is used to read the computer programs in the memory and perform the following operations:

[0056] Receive the first indication signal sent by the first node;

[0057] Based on the first indication signal, the first OFDM signal is frequency-shifted to obtain the second OFDM signal;

[0058] Send the second OFDM signal to the first node;

[0059] The first indication signal carries at least one of the following:

[0060] Set of transmission frequency offset parameters;

[0061] A-IoT device modulation method;

[0062] Subcarrier spacing;

[0063] Transmission protection interval.

[0064] This application provides a signal transmission device applicable to a first node, comprising:

[0065] The first transmitting module is configured to send a first indication signal to the first A-IoT device, wherein the first indication signal is configured to instruct the first A-IoT device to frequency shift the first orthogonal frequency division multiplexing (OFDM) signal to obtain a second OFDM signal and to transmit the second OFDM signal.

[0066] The first indication signal carries at least one of the following:

[0067] Set of transmission frequency offset parameters;

[0068] A-IoT device modulation method;

[0069] Subcarrier spacing;

[0070] Transmission protection interval.

[0071] This application provides a signal transmission device applicable to a first AIoT device, comprising:

[0072] The first receiving module is used to receive the first indication signal sent by the first node;

[0073] A frequency shift module is used to frequency shift a first OFDM signal based on the first indication signal to obtain a second OFDM signal;

[0074] The second transmitting module is used to transmit the second OFDM signal to the first node;

[0075] The first indication signal carries at least one of the following:

[0076] Set of transmission frequency offset parameters;

[0077] A-IoT device modulation method;

[0078] Subcarrier spacing;

[0079] Transmission protection interval.

[0080] This application provides a processor-readable storage medium storing a computer program that causes the processor to execute the signal transmission method provided in this application.

[0081] This application provides a computer program product, including computer instructions, which, when executed by a processor, implement the steps of the signal transmission method described above.

[0082] In this embodiment, the first node sends a first indication signal to the A-IoT device. The first indication signal may carry at least one of the following: a transmission frequency offset parameter set, the modulation method of the A-IoT device, the subcarrier spacing, and the transmission guard interval. The A-IoT device can obtain and transmit a second OFDM signal by frequency shifting the first OFDM signal according to the at least one of the above-mentioned parameters carried in the first indication signal sent by the first node, thereby realizing backscattering with frequency shift. In this way, even if the first node serves multiple A-IoT devices, the first node can send a first indication signal to each of the A-IoT devices it serves, instructing the A-IoT device to frequency shift the first OFDM signal according to the at least one of the above-mentioned parameters carried in the received first indication signal, thereby obtaining and transmitting a second OFDM signal. This can realize backscattering with frequency shift for different A-IoT devices, thereby reducing OFDM signal transmission interference during backscattering and improving the OFDM signal transmission performance of A-IoT devices during backscattering. Attached Figure Description

[0083] Figure 1 This is a schematic diagram of the network architecture applicable to the implementation of this application;

[0084] Figure 2 This is one of the schematic diagrams of a signal transmission method provided in an embodiment of this application;

[0085] Figure 3 This is a second schematic diagram of a signal transmission method provided in an embodiment of this application;

[0086] Figure 4 This is one of the schematic diagrams of a time-domain resource provided in an embodiment of this application;

[0087] Figure 5 This is a timing diagram provided in an embodiment of this application;

[0088] Figure 6 This is a schematic diagram of an A-IoT signal based on OOK-4 provided in an embodiment of this application;

[0089] Figure 7 This is a second schematic diagram of a time-domain resource provided in an embodiment of this application;

[0090] Figure 8 This is a schematic diagram of frequency domain resources provided in an embodiment of this application;

[0091] Figure 9 This is one of the schematic diagrams of a time-frequency resource provided in the embodiments of this application;

[0092] Figure 10 This is a schematic diagram of a frequency domain transmitted signal provided in an embodiment of this application;

[0093] Figure 11 This is a second schematic diagram of a time-frequency resource provided in an embodiment of this application;

[0094] Figure 12 This is a third schematic diagram of a time-frequency resource provided in an embodiment of this application;

[0095] Figure 13 This is a structural diagram of a communication device provided in an embodiment of this application;

[0096] Figure 14 This is a structural diagram of another communication device provided in an embodiment of this application;

[0097] Figure 15 This is a schematic diagram of a communication device provided in an embodiment of this application;

[0098] Figure 16 This is a schematic diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0099] To make the technical problems, technical solutions and advantages of this application clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0100] In the embodiments of this application, the term "and / or" describes the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. The character " / " generally indicates that the preceding and following associated objects have an "or" relationship.

[0101] In the embodiments of this application, the term "multiple" refers to two or more, and other quantifiers are similar.

[0102] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0103] This application provides a signal transmission method, apparatus, device, and storage medium to solve the problem of poor OFDM signal transmission performance in A-IoT devices.

[0104] The methods, apparatus, and equipment are based on the same concept of the application. Since the methods and equipment solve problems in similar ways, the implementation of the apparatus, equipment, and methods can refer to each other, and the repeated parts will not be described again.

[0105] The technical solutions provided in this application can be applied to various systems, especially 6G systems. For example, applicable systems include Global System for Mobile Communication (GSM), Code Division Multiple Access (CDMA), Wideband Code Division Multiple Access (WCDMA) General Packet Radio Service (GPRS), Long Term Evolution (LTE), LTE Frequency Division Duplex (FDD), LTE Time Division Duplex (TDD), Long Term Evolution Advanced (LTE-A), Universal Mobile Telecommunication System (UMTS), Worldwide Interoperability for Microwave Access (WiMAX), 5G New Radio (NR), and 6G systems. All of these systems include terminal equipment and network equipment. The systems may also include a core network component, such as Evolved Packet System (EPS) and 5G systems (5GS).

[0106] Please see Figure 1 , Figure 1 This is one of the structural diagrams of a network architecture applicable to the implementation of this application, such as... Figure 1 As shown, it includes a first device (e.g., an A-IoT device) 11 and a network device 12 (e.g., a base station, etc.).

[0107] In this application, the terminal device (terminal) involved in the embodiments can be a device that provides voice and / or data connectivity to a user, a handheld device with wireless connectivity, or other processing devices connected to a wireless modem. The name of the terminal device may differ in different systems; for example, in a 5G system, the terminal device can be called User Equipment (UE). The wireless terminal device can communicate with one or more core networks (CNs) via a Radio Access Network (RAN). The wireless terminal device can be a mobile terminal device, such as a mobile phone (or "cellular" phone) and a computer with a mobile terminal device, for example, a portable, pocket-sized, handheld, computer-embedded, or vehicle-mounted mobile device, which exchanges voice and / or data with the radio access network. Examples include Personal Communication Service (PCS) phones, cordless phones, Session Initiated Protocol (SIP) phones, Wireless Local Loop (WLL) stations, Personal Digital Assistants (PDAs), Redcap terminals, and Low Power Wide Area (LPWA) terminals. Wireless terminal equipment can also be referred to as a system, subscriber unit, subscriber station, mobile station, mobile terminal, remote station, access point, remote terminal, access terminal, user terminal, user agent, or user device; however, this application does not limit the terminology used in its embodiments.

[0108] The network device involved in this application embodiment can be a base station, which may include multiple cells providing services to terminals. Depending on the specific application, a base station may also be called an access point, or a device in an access network that communicates with a wireless terminal device through one or more sectors on the air interface, or other names. The network device can be used to exchange received air frames with Internet Protocol (IP) packets, acting as a router between the wireless terminal device and the rest of the access network, where the rest of the access network may include an Internet Protocol (IP) communication network. The network device can also coordinate the attribute management of the air interface. For example, the network equipment involved in the embodiments of this application can be a base transceiver station (BTS) in a Global System for Mobile communications (GSM) or Code Division Multiple Access (CDMA), a NodeB in a Wide-band Code Division Multiple Access (WCDMA) network, an evolved Node B (eNB or e-NodeB) in a long term evolution (LTE) system, a 5G base station (gNB) in a next generation system, a base station in 6G, a Home evolved Node B (HeNB), a relay node, a femto, a pico, etc., and is not limited in the embodiments of this application. In some network structures, the network equipment may include centralized unit (CU) nodes and distributed unit (DU) nodes, and the centralized unit and distributed unit may also be geographically separated.

[0109] It should be noted that the technology involved in the embodiments of this application is described as follows:

[0110] 1) Internet of Things (IoT) Topology

[0111] Based on the different node types and communication methods in the synchronization system, four IoT topologies are defined:

[0112] The first type of IoT topology is as follows: Figure 1The diagram illustrates a topology where A-IoT devices are directly connected to network devices (e.g., base stations (BS), such as 5G base stations gNBs; readers can be located within the network devices, or the reader itself may be a network device). A-IoT devices and network devices communicate directly and bidirectionally (i.e., direct communication). Communication between the network devices and A-IoT devices includes ring A-IoT data and / or signaling. This topology includes two nodes: the BS transmitting to the A-IoT device and the BS receiving from the A-IoT device. In this topology, the BS sending signals to the A-IoT device and the BS receiving signals from the A-IoT device can be different. The signal sent from the base station to the A-IoT device can be simply referred to as a Reader to Device (R2D) signal, and the signal sent from the A-IoT device to the base station can be simply referred to as a Device to Relay (D2R) signal.

[0113] The second type of IoT topology is as follows: Figure 2 The diagram shows a network topology that includes an intermediate node. This topology includes a first device (e.g., an A-IoT device) 21, a network device 22 (e.g., a base station), and an intermediate node 23 located between the A-IoT device 21 and the network device 22 (the reading device may be located at the intermediate node, or the reading device may be the intermediate node itself).

[0114] exist Figure 2 The network architecture shown is a topology for transmission between intermediate nodes and A-IoT devices. A-IoT devices communicate bidirectionally with intermediate nodes located between A-IoT devices and base stations. Communication between A-IoT devices and base stations is also facilitated through these intermediate nodes. In this topology, intermediate nodes can be relay nodes with A-IoT signal transmission capabilities, integrated access and backhaul (IAB) nodes, user equipment (UE), repeaters, etc. Intermediate nodes transmit A-IoT data and / or signaling between base stations and A-IoT devices. Signals sent from intermediate nodes to A-IoT devices can be referred to as R2D signals, and signals sent from A-IoT devices to intermediate nodes can be referred to as D2R signals.

[0115] The third type of IoT topology is as follows: Figure 3 and Figure 4The diagram illustrates a network topology that includes an assisting node. In this topology, A-IoT devices send data / signaling to the base station and receive data / signaling from the assisting node; alternatively, A-IoT devices receive data / signaling from the base station and send data / signaling to the assisting node. In this topology, the assisting node can be a relay node, IAB (Integrated Device Architecture), UE (User Equipment), repeater, etc.

[0116] The fourth type of IoT topology is as follows: Figure 5 The diagram illustrates a topology for direct communication between a terminal (UE) and an A-IoT device. In this topology, the A-IoT device and the terminal communicate bidirectionally. The communication between the UE and the A-IoT device includes A-IoT data and / or signaling.

[0117] In these topologies, A-IoT devices need to communicate with BS, auxiliary nodes, and UEs. These devices can both send data to and receive data sent by the A-IoT devices. In this embodiment, the focus is on the modulation method of data sent by the A-IoT devices, without distinguishing which devices the A-IoT devices communicate with. For the sake of simplicity, these three types of devices can be uniformly referred to as "first nodes".

[0118] 2) Frequency shift modulation

[0119] In backscattered A-IoT devices, an important parameter characterizing the antenna's reflection of ambient radio frequency signals is the antenna's reflection coefficient, which is defined as:

[0120]

[0121] The reflection coefficient of radio frequency signals by a reflective A-IoT device can be expressed as:

[0122]

[0123] Among them, Z i Z represents the antenna impedance. l This represents the load impedance. When the antenna impedance is equal to the load impedance, the reflection coefficient is 0, meaning there is no reflected wave, and all the energy of the incident wave is absorbed by the load impedance. This situation is called impedance matching. Correspondingly, the main idea behind the modulation of radio frequency signals by A-IoT devices is impedance mismatch, that is, the antenna impedance is not equal to the load impedance, the reflection coefficient is not 0, and the amplitude and phase of the reflected wave relative to the incident wave will change. A-IoT devices can obtain different reflection coefficients by controlling the changes in the load impedance, thereby modulating information onto the incident wave.

[0124] Therefore, the relationship between the reflected wave and the incident wave can be expressed in the following form:

[0125] s out (t)=s in (t)Γ(t) (3)

[0126] That is, the reflected wave is equal to the product of the incident wave and the reflection coefficient. In A-IoT devices, different modulation methods can be achieved by changing the impedance and thus the reflection coefficient.

[0127] like Figure 6 As shown, the backscattering process is equivalent to performing multiplication in the radio frequency (RF) domain. Therefore, by controlling the RF switch between two loads at a certain period through a microcontroller unit (MCU), the reflection coefficient can exhibit periodic changes. This process is equivalent to multiplying a square wave with the incident signal, using its fundamental frequency component to achieve frequency shifting of the incident signal.

[0128] Assuming an A-IoT device uses two load impedances, it can provide two reflection coefficients. When the RF switch switches between the two reflection coefficients at a certain period, Γ(t) is in the form of a square wave, as shown below. Figure 7 Show.

[0129] Substituting the reflection coefficient into the relationship between the reflected and incident waves through Fourier series expansion yields the expression for the reflected wave. Performing a Fourier transform on both sides of the equation finally yields the output signal after backscattering modulation:

[0130]

[0131] As can be seen from the above formula, when the reflection coefficients used are 0 and 1, the reflected signal spectrum still has components at the incident signal spectrum, while the original signal spectrum is shifted left and right. The shifted components can be used to achieve frequency shift modulation of backscattering, and the modulated spectrum is as follows: Figure 8 As shown, for example, there are two users in the environment. One user shifts the incident carrier frequency to F0, and the other user shifts the incident carrier frequency to F1.

[0132] The number of times the reflection coefficient switches within one symbol duration in the time domain is the symbol period / switching period, i.e., Tb / Ti. The switching period is the reciprocal of the shift frequency, i.e., Ti = 1 / Δfi. Here, i = 0 or 1, where i = 0 represents the shift frequency of modulation bit information 0, and i = 1 represents the shift frequency of modulation bit information 1.

[0133] As can be seen from the above equation (4), the distance the incident signal (incident wave) is shifted is consistent with the switching frequency of the impedance of the A-IoT device. Therefore, when the incident signal is a signal with a large bandwidth, in order to prevent the reflected signal (reflected wave) from interfering with the incident signal, the A-IoT device needs to completely shift the spectrum of the incident signal out of the bandwidth occupied by the original signal to achieve modulation with frequency shift.

[0134] Currently, in related technologies, the modulation methods used by backscattering protocols such as RFID are OOK and BPSK, and NR and WiFi systems do not use modulation methods with frequency shift. Therefore, the frequency shifting method and shifting position when backscattering with frequency shift have not yet been determined.

[0135] In addition, most backscatter systems currently use single-tone signals as incident signals, and there are no protocol standards related to backscatter modulation when the incident signal is an OFDM signal. Furthermore, LTE / NR systems in related technologies all use OFDM signals for communication. If backscatter based on single-tone signals is to be supported, a separate radio frequency source for generating single-tone signals is required for backscatter communication, resulting in a waste of resources.

[0136] Furthermore, since OFDM signals in the environment generally have a wide bandwidth, directly using OFDM signals for frequency shifting places high demands on the frequency shifting capabilities of A-IoT devices. For example, a typical Wi-Fi signal bandwidth is 20MHz. If an A-IoT device wants to use this signal for traditional FSK backscattering, it needs to switch the antenna's load impedance at least 10MHz to shift the incident signal to a spectrum that does not interfere with the original signal. This is difficult to achieve for passive A-IoT devices. Moreover, as in the example above, the A-IoT device would shift a 20MHz wide signal to an adjacent frequency band to achieve a transmission rate of hundreds or even tens of kbps, resulting in extremely low spectrum utilization and a significant waste of frequency resources.

[0137] This application provides an OFDM signal for backscattering, enabling as many A-IoT devices as possible to achieve FDM transmission of reflected signals based on the OFDM signal, thereby improving resource utilization and increasing the capacity of the A-IoT communication system.

[0138] Please see Figure 9 , Figure 9 This is a flowchart of a signal transmission method provided in an embodiment of this application, applied to the first node, such as... Figure 9 As shown, it includes the following steps:

[0139] Step 901: Send a first indication signal to the first A-IoT device. The first indication signal is used to instruct the first A-IoT device to frequency shift the first OFDM signal to obtain a second OFDM signal and send the second OFDM signal.

[0140] The first indication signal carries at least one of the following:

[0141] Set of transmission frequency offset parameters;

[0142] A-IoT device modulation method;

[0143] Subcarrier spacing;

[0144] Transmission protection interval.

[0145] It should be understood that the first node can send a first indication signal to one or more A-IoT devices served by the first node in the environmental IoT. The first A-IoT device can be a device among the A-IoT devices served by the first node. Additionally, the first node can send a first OFDM signal to these A-IoT devices. After receiving the first OFDM signal, each A-IoT device can perform backscattering based on the first OFDM signal, that is, reflect a second OFDM signal based on the first OFDM signal, thus achieving backscatter communication. It should be noted that the A-IoT device can send the second OFDM signal to the first node, or it can send the second OFDM signal to a second node (e.g., other nodes in the environmental IoT that are different from the first node, and the second node can serve the A-IoT device). In this embodiment, the first node can send a first indication signal to the A-IoT device, thus instructing the A-IoT device to modulate and shift the received first OFDM signal according to the first indication signal, i.e., to perform frequency shifting, to obtain and send the second OFDM signal, thereby achieving frequency-shifted backscattering. The second OFDM signal is also a D2R signal.

[0146] It should be noted that the transmission guard interval can be understood as the guard interval between D2R transmissions of A-IoT devices. Additionally, as an example, the aforementioned set of transmission frequency offset parameters may include the frequency offset parameters corresponding to each A-IoT device among the A-IoT devices (one or more, i.e., at least one A-IoT device) served by the first node. The frequency offset parameters corresponding to different A-IoT devices may be at least partially different. The frequency offset parameter is an offset parameter relative to the center frequency, and the frequency offset parameter is a positive integer. The center frequency can be the center position of the frequency domain location of the first OFDM signal. The first A-IoT device is a device among the A-IoT devices served by the first node. After receiving the first indication signal, each A-IoT device can frequency-shift the first OFDM signal based on the corresponding frequency offset parameter. This allows different A-IoT devices to frequency-shift the first OFDM signal to corresponding frequency points for backscattering. For example, different A-IoT devices may have different frequency offset parameters, allowing different A-IoT devices to frequency-shift the first OFDM signal to different frequency points for backscattering. Additionally, as an example, the A-IoT device can shift the first OFDM signal by a frequency offset parameter corresponding to the A-IoT device, multiple times the subcarrier interval. For example, the frequency offset parameter corresponding to the A-IoT device may include frequency offset parameters corresponding to different bit information, with different frequency offset parameters for different bit information. For instance, the A-IoT device transmits bit 0 and bit 1, respectively, corresponding to different frequency offset parameters. Furthermore, it should be noted that the A-IoT device can shift the first OFDM signal by modulation. The modulation method of the A-IoT device can be various and not specifically limited. For example, as an example, the modulation method of the A-IoT device mentioned above in this application may include, but is not limited to, Frequency Shift Keying (FSK) modulation or Minimum Shift Keying (MSK) modulation.

[0147] In this embodiment, the first node sends a first indication signal to the A-IoT device. The first indication signal may carry at least one of the following: a transmission frequency offset parameter set, the modulation method of the A-IoT device, the subcarrier spacing, and the transmission guard interval. The A-IoT device can obtain and transmit a second OFDM signal by frequency shifting the first OFDM signal according to the at least one of the above-mentioned parameters carried in the first indication signal sent by the first node, thereby realizing backscattering with frequency shift. In this way, even if the first node serves multiple A-IoT devices, the first node can send a first indication signal to each of the A-IoT devices it serves, instructing the A-IoT device to frequency shift the first OFDM signal according to the at least one of the above-mentioned parameters carried in the received first indication signal, thereby obtaining and transmitting a second OFDM signal. This can realize backscattering with frequency shift for different A-IoT devices, thereby reducing OFDM signal transmission interference during backscattering and improving the OFDM signal transmission performance of A-IoT devices during backscattering.

[0148] In some embodiments, the frequency offset of the second OFDM signal relative to the first OFDM signal is a positive integer multiple of the subcarrier spacing.

[0149] It should be understood that the first OFDM signal is the incident signal of the A-IoT device. The backscattering A-IoT device can reflect the incident OFDM signal after frequency shifting by a positive integer multiple of the subcarrier spacing, thus achieving frequency-shifted backscattering. In this way, even if the first node serves multiple A-IoT devices, the first node can send a first indication signal to different A-IoT devices to instruct the A-IoT devices to perform frequency shifting of the first OFDM signal by a positive integer multiple of the subcarrier spacing based on at least one of the above-mentioned parameters carried in the first indication signal, thereby obtaining and transmitting the second OFDM signal. This enables frequency-shifted backscattering by different A-IoT devices, reducing OFDM signal transmission interference during backscattering and improving the OFDM signal transmission performance of A-IoT devices during backscattering.

[0150] In some embodiments, the transmission frequency offset parameter set includes frequency offset parameters corresponding to each of the at least one A-IoT devices. The frequency offset parameters corresponding to each A-IoT device may include frequency shift parameters of multiple bits. The frequency shift parameters of the bits corresponding to different A-IoT devices may be at least partially different. The frequency offset used by the A-IoT device to frequency shift the first bit information of the first OFDM signal may be the product of the frequency offset parameter corresponding to the first bit information in the frequency offset parameters corresponding to the A-IoT device and the subcarrier spacing. The at least one A-IoT device includes a first A-IoT device, and the first bit information is any bit information among the multiple bits.

[0151] In some embodiments, before sending the first indication signal to the first environmental Internet of Things (A-IoT) device, at least one of the following is further included:

[0152] The length of the frequency domain sequence is determined based on the set of transmission frequency offset parameters; or...

[0153] Obtain the length of the frequency domain sequence; based on the length of the frequency domain sequence, determine the set of transmission frequency offset parameters.

[0154] In this embodiment, there are two ways to select the frequency domain sequence length and the transmission frequency offset parameter, and either method can be used. Method 1: The first node can first obtain the frequency domain sequence length L, and then determine the frequency offset parameter set based on the frequency domain sequence length L. Method 2: The first node can first obtain the transmission frequency offset parameter set, and then determine the frequency domain sequence length L based on the transmission frequency offset parameter set. Afterwards, on the one hand, the first node can send a first indication signal to the A-IoT device, which can carry the transmission frequency offset parameter set to facilitate frequency shift reflection by the A-IoT device. On the other hand, the transmission frequency offset parameter set and the frequency domain sequence length can be used to determine the frequency domain resources for the first node to receive the second OFDM signal reflected by the A-IoT device, so that the first node can receive the reflected OFDM signal.

[0155] In some embodiments, the total length of the transmission guard interval and the frequency domain sequence length is less than or equal to the target value, or the frequency domain sequence length is less than or equal to the target value;

[0156] The target value is either the first value or the minimum of the first and second values. The first value is the minimum difference between any two frequency offset parameters in the transmission frequency offset parameter set, and the second value is the minimum frequency offset parameter in the transmission frequency offset parameter set.

[0157] That is, by using either of the two selection methods mentioned above to select the frequency domain sequence length and transmission frequency offset parameters, the selected frequency domain sequence length and transmission frequency offset parameters shall satisfy the following constraints: when including the transmission guard interval, the total length of the transmission guard interval and the frequency domain sequence length shall be less than or equal to the minimum difference between any two frequency offset parameters in the transmission frequency offset parameter set or the minimum frequency offset parameter in the transmission frequency offset parameter set; or when excluding the transmission guard interval, the frequency domain sequence length shall be less than or equal to the minimum difference between any two frequency offset parameters in the transmission frequency offset parameter set or the minimum frequency offset parameter in the transmission frequency offset parameter set.

[0158] In some embodiments, the method further includes:

[0159] Based on the transmission frequency offset parameter set and the frequency domain sequence length, the frequency domain resources used by the first node to receive the second OFDM signal are determined.

[0160] That is, after determining the set of transmission frequency offset parameters and the length of the frequency domain sequence, the frequency domain resources can be determined using the set of transmission frequency offset parameters and the length of the frequency domain sequence, so that the first node can receive the second OFDM signal reflected by the A-IoT device.

[0161] In some embodiments, the frequency domain resources include X subcarriers, where X is a value of 2*N. 1,1max +L+N′; where L is the length of the frequency domain sequence, N 1,1max N′ is the maximum frequency offset parameter in the set of transmission frequency offset parameters, N′ is the number of subcarriers occupied by the first guard interval, and N′ is an integer greater than or equal to 0.

[0162] To ensure that the second OFDM signal reflected by the A-IoT device is within the frequency band of this frequency domain resource, the bandwidth of this frequency domain resource is (2*N). 1,1max +L+N′)*Δf, where Δf is the subcarrier spacing, i.e., the number of subcarriers X is 2*N. 1,1max +L+N′. It should be noted that a transmission protection interval (q) can be reserved between the frequency resources of the reflected OFDM signal. If an additional first protection interval is reserved for OFDM signal transmission, then N′ can be the number of subcarriers occupied by the first protection interval. For example, if 20 subcarriers are reserved as protection bandwidth at both ends of the entire D2R signal (e.g., one end of the second OFDM signal corresponding to the maximum frequency offset (the upper and lower ends), i.e., both ends), then the number of subcarriers occupied by the first protection interval is 40, and N′ = 40. It should be noted that the first protection interval can be predefined through the protocol.

[0163] In this embodiment, the frequency domain resources include X subcarriers, where X can be 2*N. 1,1max +L+N′, where L is the length of the frequency domain sequence, N 1,1max The maximum frequency offset parameter in the transmission frequency offset parameter set is N′, which is the number of subcarriers occupied by the first guard interval. In this way, subcarriers to be used for backscattering, frequency domain sequence length, and transmission guard interval are reserved. Thus, the first node can receive the reflected OFDM signal after frequency shifting the first OFDM signal in the frequency domain resources including the above-mentioned X subcarriers, and realize backscatter communication.

[0164] In some embodiments, before sending the first indication signal to the first environmental Internet of Things (A-IoT) device, the method further includes: determining a frequency domain sequence, wherein the length of the frequency domain sequence is the length of the frequency domain sequence;

[0165] After determining the frequency domain resources for the first node to receive the second OFDM signal based on the transmission frequency offset parameter set and the frequency domain sequence length, the process includes: detecting the second OFDM signal on the frequency domain resources, and demodulating the second OFDM signal based on the frequency domain sequence to obtain the received bit information.

[0166] Before sending the first indication signal, the first node can generate a frequency domain sequence. It should be noted that the first node can generate various types of frequency domain sequences, and this embodiment does not impose a specific limitation. For example, the frequency domain sequence generated by the first node in this embodiment may include a ZC sequence of length L (i.e., a Zadoff-Chu sequence, a complex sequence with good autocorrelation and cross-correlation properties), a gold sequence of length L, etc. As an example, the frequency domain sequence corresponds to the center position of X subcarriers of the frequency domain resource; it can be understood that the frequency domain sequence is placed at the center position of the frequency domain resource used to receive the second OFDM signal.

[0167] In this embodiment, the first node can generate a frequency domain sequence of length L for backscatter communication of A-IoT devices. After determining the frequency domain resources, the second OFDM signal reflected by the A-IoT device can be detected on the frequency domain resources, and the frequency domain sequence can be used to demodulate the second OFDM signal to obtain the received bit information.

[0168] In some embodiments, the received bit information is obtained by demodulating the second OFDM signal based on the frequency domain sequence, including:

[0169] The second OFDM signal is received at the first frequency position of the subcarrier offset by the first frequency offset parameter relative to the frequency domain sequence. The frequency correlation between the frequency domain sequence and the second OFDM signal received at the first frequency position is calculated to obtain the first correlation. The first frequency offset parameter is a parameter in the transmission frequency offset parameter set and is the frequency offset parameter used by the first A-IoT device when sending the first bit.

[0170] The second OFDM signal is received at the second frequency position of the subcarrier offset by the second frequency offset parameter relative to the frequency domain sequence. The frequency correlation between the frequency domain sequence and the second OFDM signal received at the second frequency position is calculated to obtain the second correlation. The second frequency offset parameter is a parameter in the transmission frequency offset parameter set and is the frequency offset parameter used by the first A-IoT device when sending the second bit.

[0171] The bit information is determined based on the first and second correlation scores.

[0172] When transmitting bit information, OFDM modulation maps the bit information into OFDM symbols (i.e., OFDM signals) before transmission. The demodulation process involves frequency-domain demodulation of the OFDM signal to obtain the bit information. It should be understood that A-IoT devices use different frequency offset parameters when transmitting different bit information. For example, the first bit corresponds to a first frequency offset parameter, and the second bit corresponds to a second frequency offset parameter. Furthermore, it should be noted that the first OFDM signal transmitted by the first node, after being reflected by the first A-IoT device (i.e., reflecting the second OFDM signal), will generate a copy of the frequency domain sequence of the second OFDM signal symmetrically around the frequency band center at the corresponding frequency offset position of the transmitted bit information. Therefore, in the demodulation of the second OFDM signal in this embodiment, the frequency correlation of the second OFDM signal received at a first frequency position offset by a first frequency offset parameter number of subcarriers relative to the frequency domain sequence can be calculated to obtain a first correlation. Furthermore, the frequency correlation of the second OFDM signal received at a second frequency position offset by a second frequency offset parameter number of subcarriers relative to the frequency domain sequence can be calculated to obtain a second correlation. Based on the first and second correlations, the bit information is determined, thus achieving demodulation. It should be noted that the correlation in this embodiment can be understood as correlation or similarity in the frequency domain; a higher correlation indicates greater correlation or similarity, and vice versa. As an example, in determining the bit information based on the first and second correlations, the first and second correlations can be compared, and the bit information is determined according to the comparison result. For example, if the first correlation is greater than the second correlation, the received bit is determined to be the first bit; otherwise, the received bit is determined to be the second bit. For example, if the first bit is 1 and the second bit is 0, the received bit is determined to be 1 if the first relevance is greater than the second relevance, and 0 otherwise.

[0173] In this embodiment, a first correlation can be obtained by calculating the frequency correlation between the frequency domain sequence and the second OFDM signal received at the first frequency position, and a second correlation can be obtained by calculating the frequency correlation between the frequency domain sequence and the second OFDM signal received at the second frequency position. Based on the first correlation and the second correlation, the bits sent by the A-IoT device can be determined to demodulate the second OFDM signal.

[0174] In some embodiments, the transmission frequency offset parameter set includes a frequency offset parameter corresponding to each of the at least one A-IoT devices, and the at least one A-IoT device includes a first A-IoT device;

[0175] The first indication signal also carries at least one of the following:

[0176] The time corresponding to each of the at least one A-IoT devices is used to instruct the A-IoT device to send a second OFDM signal at the time using the frequency offset parameter corresponding to the A-IoT device.

[0177] The at least one A-IoT device can be at least one of the A-IoT devices served by the first node, or it can be all or some of the A-IoT devices served by the first node. The transmission frequency offset parameter set can include frequency offset parameters corresponding to each of the at least one A-IoT devices, and the frequency offset parameters corresponding to each A-IoT device are at least partially different. The first A-IoT device is a device among the at least one A-IoT devices. Furthermore, it should be noted that the time corresponding to the A-IoT device can be understood as the time when the A-IoT device transmits the second OFDM signal. As an example, the time corresponding to each of the at least one A-IoT devices can be different. This ensures that different A-IoT devices reflect the second OFDM signal at different times, reducing OFDM signal transmission interference and improving OFDM signal transmission efficiency.

[0178] In this embodiment, the first indication signal can carry at least one of the following: transmission frequency offset parameter set, A-IoT device modulation method, subcarrier spacing and transmission guard interval. It can also carry the time corresponding to each of the at least one A-IoT devices. The A-IoT device can send a second OFDM signal at its corresponding time to achieve OFDM signal reflection. In this way, different A-IoT devices can reflect OFDM signals at their respective times, which can reduce OFDM signal reflection interference and improve OFDM signal transmission performance.

[0179] Please see Figure 10 , Figure 10 This is a flowchart of a signal transmission method provided in an embodiment of this application, applied to a first A-IoT device, such as... Figure 10 As shown, it includes the following steps:

[0180] Step 1001: Receive the first indication signal sent by the first node;

[0181] Step 1002: Based on the first indication signal, frequency shift the first OFDM signal to obtain the second OFDM signal;

[0182] Step 1003: Send the second OFDM signal to the first node;

[0183] The first indication signal carries at least one of the following:

[0184] Set of transmission frequency offset parameters;

[0185] A-IoT device modulation method;

[0186] Subcarrier spacing;

[0187] Transmission protection interval.

[0188] In some embodiments, the total length of the transmission guard interval and the frequency domain sequence length is less than or equal to the target value, or the frequency domain sequence length is less than or equal to the target value;

[0189] The target value is either the first value or the minimum of the first and second values. The first value is the minimum difference between any two frequency offset parameters in the transmission frequency offset parameter set, and the second value is the minimum frequency offset parameter in the transmission frequency offset parameter set.

[0190] In some embodiments, the frequency offset of the second OFDM signal relative to the first OFDM is a positive integer multiple of the subcarrier spacing.

[0191] In some embodiments, the transmission frequency offset parameter set includes a frequency offset parameter corresponding to each of the at least one A-IoT devices, and the at least one A-IoT device includes a first A-IoT device;

[0192] The first indication signal also carries at least one of the following:

[0193] At least one A-IoT device, each A-IoT device has a corresponding time, the time corresponding to the A-IoT device is used to instruct the A-IoT device to send a second OFDM signal at the time using the frequency offset parameter corresponding to the A-IoT device, and the time corresponding to the first A-IoT device is the first time;

[0194] Sending the second OFDM signal to the first node includes: sending the second OFDM signal to the first node at a first time.

[0195] The process of the above method will be specifically described below with some specific embodiments.

[0196] The embodiment of this application describes an A-IoT backscattering system that uses OFDM signals as carrier (CW) signals. Different A-IoT devices backscatter OFDM signals by modulating and shifting them to different frequencies, thereby transmitting D2R signals carrying information to the receiving end (e.g., the first node). Each shift frequency (frequency shift / frequency offset / frequency domain shift) is a positive integer multiple of the subcarrier spacing. The D2R signals transmitted by different A-IoT devices at different frequencies do not overlap, i.e., frequency division multiplexing (FDM) transmission. The CW transmitting node determines the OFDM signal sequence length based on the frequency offset of all FDM-transmitting A-IoT devices, or the network side (network devices, e.g., base stations) determines the frequency domain shift of FDM transmission by different A-IoT devices based on the OFDM signal sequence length transmitted by the CW transmitting node.

[0197] The overall method of this application embodiment is as follows:

[0198] First node side (e.g., Reader side):

[0199] The first node determines the frequency domain sequence of length L used for backscatter communication of all A-IoT devices, the set of transmission frequency offset parameters (e.g., the set of D2R transmission frequency offset parameters), and the number of subcarriers q occupied by the guard interval between D2R transmissions (i.e., transmission guard interval / D2R transmission guard interval), where q is a non-negative integer.

[0200] The first node is a network device (e.g., a base station) and / or a relay node (e.g., a user equipment (UE, also known as a terminal device)).

[0201] The aforementioned set of transmission frequency offset parameters may include In this set of frequency offset parameters, every element is a positive integer. This can represent the m-th D2R transmission of the Kth (positive integer)th transmission. K (Positive integer) frequency offset parameters relative to the center frequency of the frequency domain transmission position can also represent the m-th frequency of the K-th A-IoT device among the A-IoT devices served by the first node. K The frequency offset parameter of the frequency domain transmission position relative to the center frequency, N K This can be understood as the frequency offset parameter corresponding to the Kth A-IoT device, which may include m. K Each frequency offset parameter, i.e.

[0202] Specifically, the frequency domain sequence length L is not greater than the minimum difference between any two frequency offset parameters in the frequency offset parameter set, or is not greater than the minimum value of any frequency offset parameter in the frequency offset parameter set; or, the total length of the frequency domain sequence length L and the D2R transmission guard interval q is not greater than the minimum difference between any two frequency offset parameters in the frequency offset parameter set, or is not greater than the minimum value of any frequency offset parameter in the frequency offset parameter set. That is, any two elements in the frequency offset parameter set satisfy the following condition: Constraints or satisfactions The positive integer constrained, where and N i,j All of these are any elements in the set of frequency offset parameters. When this constraint is satisfied, the frequency domain sequence length and device reflection offset can be selected in the following two ways;

[0203] Method 1: The first node first obtains the frequency domain sequence length L, then determines the set of frequency offset parameters, such that the difference between any two frequency offset parameters in the set, or the minimum value of any frequency offset parameter in the set, is not less than the frequency domain sequence length L, or not less than the total length of the frequency domain sequence length L and the D2R transmission guard interval q. or

[0204] Method 2: The first node first obtains the frequency offset parameter set of the A-IoT device, ensuring that the total length of the frequency domain sequence length L and / or the D2R transmission guard interval q is no greater than the minimum value of the difference between any two elements in the frequency offset parameter set and / or the minimum value of the frequency offset. That is, L ≤ min - q, or

[0205] In some embodiments, the values ​​of all elements in the frequency offset parameter set can be predefined by the protocol, and the frequency domain sequence length L can be predefined by the protocol.

[0206] The first node determines the frequency domain resources for receiving the D2R signal based on the D2R transmission frequency parameter set and the frequency domain sequence length L. These frequency domain resources can contain X subcarriers, meaning the number of subcarriers in this frequency domain resource is X. As an example, the value of X can be... This means reserving all subcarriers to be used for backscattering, the length of the frequency domain sequence, and the guard interval. Here, N′ represents the number of subcarriers occupied by the first guard interval at both ends of the overall D2R signal, and N′ is a non-negative integer.

[0207] The first node will send a first indication signal to the A-IoT device. The first indication signal may carry at least one of the following information:

[0208] D2R transmission frequency offset parameter set;

[0209] A-IoT device modulation method;

[0210] Subcarrier spacing;

[0211] D2R transmission protection interval q.

[0212] The first node is based on the frequency domain sequence and its relevance Y to frequency domain resources. i,j Determine the received bit information.

[0213] A-IoT device side:

[0214] An A-IoT device receives an instruction from the first node or determines at least one of the following pieces of information according to a protocol predefined:

[0215] D2R transmission frequency offset parameter set, modulation method, subcarrier spacing, and D2R transmission guard interval q.

[0216] A-IoT devices send D2R transmissions based on at least one of the above information.

[0217] In the method of this application embodiment, the first node can send a first indication signal to the A-IoT device, carrying at least one of the following: a transmission frequency offset parameter set, the modulation method of the A-IoT device, the subcarrier spacing, and the transmission guard interval. The A-IoT device can then frequency-shift the first OFDM signal based on this signal to obtain and transmit a second OFDM signal, thereby achieving backscattering with frequency shift. In this way, even if the first node serves multiple A-IoT devices, the first node can send a first indication signal to each of the A-IoT devices it serves, instructing the A-IoT device to frequency-shift the first OFDM signal based on the at least one of the above-mentioned parameters carried in the received first indication signal, thereby obtaining and transmitting a second OFDM signal. This method can achieve backscattering with frequency shift for different A-IoT devices, thereby reducing OFDM signal transmission interference during backscattering and improving the OFDM signal transmission performance of the A-IoT device during backscattering.

[0218] Furthermore, the embodiments of this application can enable the reflected signal and the incident signal to share the same bandwidth, and the A-IoT device does not need to completely shift the signal out of the original signal spectrum range to achieve backscatter communication with frequency shift. Moreover, compared with traditional frequency shift keying backscatter communication, it effectively improves spectrum utilization and reduces the requirements for A-IoT device manufacturing.

[0219] Example 1: Communication process between A-IoT device and first node:

[0220] This application embodiment can employ either FSK modulation or MSK modulation. In this embodiment, we consider an A-IoT device communicating with a base station using FSK modulation. In FSK modulation, the A-IoT device transmits bits "0" and "1" with different frequency offset parameters. Therefore, in this embodiment, the set of frequency offset parameters includes frequency offset parameter N. 1,1 and frequency offset parameter N 1,2 Two elements. The scheduling process is as follows:

[0221] The base station transmission process includes:

[0222] (1.0): The base station determines the frequency offset parameter N corresponding to the reflected bit "0" of the A-IoT device. 1,1 =15, the frequency offset parameter N corresponding to the reflection bit "1" 1,2 =45. The first node sends the above parameters to the A-IoT device via a first indication signal (e.g., R2D signaling).

[0223] (1.1): The offset N of the bit '0' sent by the A-IoT device 1,1 Subcarrier spacing, bit '1' offset N 1,2 To ensure that the frequency domain signals reflected by the A-IoT device do not overlap, a guard interval of one subcarrier spacing is added between each frequency band after reflection, q=1, according to the constraint relationship N 1,2 -N 1,1 -q = 29 or the constraint relationship min{|N 1,2 -N 1,1 |,min{N i,j}}-q=min{45-15,15}-1=15. The first constraint relationship is used when the A-IoT device uses a bipolar (-1, +1) reflection coefficient, and the second constraint relationship is used when the A-IoT device uses a unipolar (0, 1) reflection coefficient. In this embodiment, if the A-IoT device uses a bipolar reflection coefficient, the frequency domain sequence length L is a positive integer not greater than 29. The base station generates a frequency domain sequence of length not greater than 29 for backscattering. The frequency domain sequence can be any sequence type with good correlation; this application does not impose any restrictions. In this embodiment, a ZC sequence is used as an example, assuming the base station generates a ZC sequence of length 29.

[0224] (1.3): The base station determines the frequency domain resources required for backscatter transmission based on the D2R transmission frequency offset parameter set {15, 45} and the frequency domain sequence length 29. To ensure that the signal reflected by the A-IoT device remains within this bandwidth, the bandwidth of this resource segment can be (2*max{N 1,1 N 1,2In this example, Δf is calculated as}+L+N′)*Δf. In this instance, 20 subcarriers are reserved as guard bandwidth above and below the entire D2R signal, so N′=40. In this example, the A-IoT device uses a bipolar reflection coefficient, so the available frequency domain resources for D2R transmission are 2*45+29+40=159 subcarriers, i.e., X is 159, and each subcarrier is one RE. The following description will use the A-IoT device using a bipolar reflection coefficient as an example.

[0225] (1.4): The 159 subcarrier numbers are incremented by 1 sequentially from low frequency to high frequency. These subcarrier numbers are the RE index values ​​of the resources used for transmission. Assume the first subcarrier number is 1, and so on. The generated ZC sequence is placed at the center of the 159 subcarriers, i.e., on the subcarriers with subcarrier numbers 66 to 94, and the correspondence between the ZC sequence and the device is saved for data demodulation.

[0226] (1.5): Use the time-frequency resource block obtained in the previous step to generate an OFDM signal and continuously send it to the A-IoT device.

[0227] A-IoT device reflection process:

[0228] The A-IoT device reflects the signal sent by the first node within the time specified by the R2D signaling. The A-IoT device transmits bits 1 and 0 by switching impedance at different frequencies. The impedance switching frequency here is the value sent by the first node to the A-IoT device via a second indication signal (e.g., R2D signaling), and the impedance switching frequency is N. 1,1 Δf indicates that bit 0 is transmitted, and the impedance switching frequency is N. 1,2 Δf indicates that bit 1 is being sent.

[0229] The first node receiving process includes:

[0230] (2.1): Backscattered signals are detected in the 159 carrier frequency domain resources determined during the first node's transmission process, which correspond to the frequency band detection signals for A-IoT operation. This is done at a relative frequency domain sequence offset of N. 1,1 Correlation is performed in the frequency domain using a ZC sequence of length 29 at each subcarrier offset frequency domain position to obtain the frequency domain correlation Y. 1,1 Similarly, in the relative frequency domain sequence offset N 1,2 Correlation is performed in the frequency domain using a ZC sequence of length 29 at each subcarrier offset frequency domain position to obtain the frequency domain correlation Y. 1,2 .

[0231] (2.2): Comparison of correlation Y 1,1 With Y 1,2 The size of Y 1,1 >Y 1,2If the value is 0, it is considered that the A-IoT device is sending bit 0; otherwise, it is considered that the A-IoT device is sending bit 1.

[0232] Example 2: Backscattered A-IoT device performs a positive integer multiple frequency shift on the incident OFDM signal based on the subcarrier spacing; transmission and reception process:

[0233] OFDM signals, as a ubiquitous communication signal in the environment, are very suitable as a signal source for backscattering systems. Considering the system topology as follows... Figure 1 or Figure 5 This example considers a communication system that includes a first node and an A-IoT device communicating directly. The A-IoT device can perform frequency shift keying modulation on the incident signal, and the first node receiver can perform frequency domain correlation demodulation on the signal reflected from the A-IoT device, thus completing backscatter communication. In Topo 1, the first node is the base station; in Topo 2, the first node is the relay node (UE). In this example, the first node refers to the base station.

[0234] When a unipolar square wave is used to shift the frequency of an A-IoT device by an integer multiple of the subcarrier spacing, the reflection coefficient is 0 or 1. The original frequency domain symbol, in addition to its original frequency position, is symmetrically shifted vertically by a certain distance in the frequency domain. Specifically, with the center frequency of the used frequency band as the symmetrical point, a copy of the frequency domain sequence appears at the original frequency position and at the two shifted frequency positions, thus achieving backscattered frequency shift keying modulation when the incident signal is OFDM. If a bipolar square wave is used in the above process, i.e., the reflection coefficient is ±1, no copy will appear at the original frequency position. However, two copies will still exist at the other two shifted frequency positions.

[0235] This example considers an A-IoT device communicating with a base station using FSK modulation. In FSK modulation, the A-IoT device sends bit 0 and bit 1, respectively, corresponding to different frequency offset values. Therefore, the set of transmission frequency offset parameters in this embodiment includes N. 1,1 and N 1,2 Two elements. In this embodiment, the frequency offset parameter can be predefined by the protocol. For example, when the A-IoT device sends bit '0', the frequency shift distance is 240kHz; when the A-IoT device sends bit '1', the frequency shift distance is 690kHz. The OFDM signal subcarrier spacing is 15kHz, i.e., N. 1,1 =16,N 1,2=32. In this embodiment, considering that the A-IoT device uses a unipolar reflection coefficient, one subcarrier is reserved between each frequency band of D2R as a transmission protection interval, i.e., q=1. Twenty subcarriers are reserved at both ends of the entire D2R signal as external protection intervals (i.e., the first protection interval), i.e., N′=40; then according to the constraint relationship min{|N 1,2 -N 1,1 |,min{N i,j}}-q=min{32-16,16}-1=15 determines that the frequency domain sequence length L is 15, and the total number of subcarriers occupied by the D2R signal is 2*32+15+40=119.

[0236] At the first node, a ZC sequence of length 15 (i.e., the corresponding frequency domain sequence) is placed at the center of the OFDM bandwidth, such as... Figure 11 As shown. In Figure 11 In (a) and (b), the left side shows the frequency domain placement of the OFDM symbols at the transmitting end, and the right side shows the frequency domain position of the OFDM symbols after reflection by the A-IoT device. If the A-IoT device uses a bipolar reflection coefficient, the frequency domain resource occupancy before and after the reflected signal is shown in the diagram below. Figure 12 As shown in the figure, after the signal emitted by the signal source is reflected by the A-IoT device, two copies of the frequency domain sequence are generated symmetrically with the frequency band center at the corresponding frequency offset position of the transmitted bit; when the A-IoT device transmits bit '1', corresponding to N 1,2 =32 frequency offset distance, such as Figure 11 As shown, the received signal has two frequency domain sequence copies at y1 and y4, and no symbols at y2 and y3; the situation is exactly the opposite when the A-IoT device sends bit '0', N 1,1 =16 frequency offset distance corresponds to the frequency replicas at y2 and y3. Therefore, the receiver can use the frequency domain sequence to correlate with the symbols at the two received positions and compare the correlation strength. Specifically, after the receiver of the first node receives the backscattered signal, the demodulation process is as follows:

[0237] (3.1): Perform FFT on the received reflected signal to obtain its frequency domain resources and find the part used for backscattering.

[0238] (3.2): For example Figure 11 As shown, the first node uses the frequency domain sequence selected during transmission to perform correlation at the frequency domain positions y1, y2, y3, and y4 of the received signal to obtain c1, c2, c3, and c4, respectively.

[0239] (3.3): Comparing two correlations Y 1,1 =c1+c4 and Y 1,2= c2 + c3. If the former is larger, the received bit is considered to be 1. Otherwise, the received bit is considered to be 0, i.e., equation (9).

[0240] This completes one backscatter transmission.

[0241] Example 3: An A-IoT device communicates with a base station using FSK modulation. The length L of the frequency domain sequence generated by the first node needs to meet the following requirements. Constraints, and For any two elements in the transmission frequency offset set.

[0242] In this example, consider the first node sending an indication signal to the A-IoT device via R2D signaling, so that the A-IoT device can determine the parameters used for backscatter transmission. In this example, the first node is taken as the UE.

[0243] First, the first node needs to determine the transmission parameters, including the frequency domain sequence length, the frequency shift when transmitting different bits, and the subcarrier spacing. The frequency shift when transmitting different bits must be an integer multiple of the subcarrier spacing; here, the subcarrier spacing is taken as 30kHz. For example, the corresponding frequency offset parameter N... 1,1 =10, when the A-IoT device sends bit '1', the frequency shift distance is 600kHz, and when the A-IoT device sends bit '0', the frequency shift distance is 300kHz. For example, the corresponding frequency offset parameter N 1,2 =20. When selecting the length of the frequency domain sequence, two factors need to be considered. First, in the signal with frequency offset after reflection by the A-IoT device, there should be no overlap between the frequency domain sequences after frequency offset. Second, appropriate guard intervals need to be added between the frequency domain sequences after frequency offset to improve the robustness of the system.

[0244] Assuming the starting position of the frequency domain sequence index is 'a', the corresponding frequency domain sequence length is 'L', and the A-IoT device transmits bit '0' with an offset of 'N'. 1,1 Subcarrier spacing, bit '1' offset N 1,2 With a subcarrier interval, when transmitting bits '0' and '1', and without considering the guard intervals of each segment of the D2R signal, the corresponding offset frequency domain sequence and data position are shown in Table 1 below.

[0245] Table 1

[0246]

[0247] Based on the size relationship between the indices, inequalities can be listed to obtain the relationship between the length of the frequency domain sequence and the shift frequency that must satisfy (10):

[0248] L≤N 1,2 -N 1,1 (10)

[0249] In this example, the calculated length of the frequency domain sequence needs to satisfy the condition L≤10. When L=10, the four frequency domain sequences after reflection are closely connected. To improve the robustness of the system, we now consider adding a 30kHz guard interval between each pair, i.e., take L=8.

[0250] In summary, the first node has completed the determination of the backscattering transmission parameters. Afterwards, the first node will... 1,1 =10, N 1,2 =20 and the subcarrier spacing Δf=30kHz of the OFDM signal are sent to the A-IoT device via R2D signaling. This invention does not restrict the transmission waveform and modulation method used in this process. After receiving the R2D signaling, the A-IoT device sets the corresponding parameters and begins backscatter transmission. The first node receiver demodulates the bits sent by the A-IoT device by detecting the position and energy magnitude of the four frequency domain sequences set in the frequency domain of the reflected signal.

[0251] Example 4: Multiple A-IoT users communicate with the first node using different modulation methods:

[0252] This embodiment considers that, using the same time-domain resources, the first node communicates with two users via FDM, and both devices use FSK modulation. Therefore, the transmission frequency offset parameter set in this embodiment may include N. 1,1 N 1,2 N 2,1 N 2,2 Four elements. Taking the first node as the base station as an example, its communication process is as follows:

[0253] First node sending process:

[0254] (4.1): The first node determines the subcarrier spacing Δf of the OFDM signal used for transmission, the modulation method of the A-IoT device, and the frequency offset parameter N corresponding to the reflection. 1,1 =8, N 1,2 =24, N 2,1 =40, N 2,2 =56; Both devices use FSK modulation, and the A-IoT device's reflection coefficient uses a bipolar form. The first node sends the above parameters to the A-IoT device via R2D signaling.

[0255] (4.2): The length of the frequency domain sequence used for backscattering is determined while ensuring that the frequency bands occupied by all devices do not overlap. Two subcarrier intervals are reserved between the frequencies corresponding to each A-IoT device after reflection as a guard bandwidth, i.e., q = 2, according to the constraint relationship. That is, the length L of the frequency domain sequence is a positive integer not greater than 14. The frequency domain sequence can be any sequence type with good correlation. This invention does not impose any restrictions. In this embodiment, the ZC sequence is used as an example for illustration. It is assumed that the first node generates a ZC sequence of length 14 for backscattering incident signal generation.

[0256] (4.3): The first node allocates a frequency domain resource for backscatter transmission based on the above parameters. The bandwidth of this resource segment is... To ensure that the signal reflected by the A-IoT device remains within this bandwidth, Δf is the subcarrier spacing of the OFDM signal, and N′ is the number of subcarriers occupied by the guard intervals at both ends of the entire D2R signal, N′=10. Therefore, the available frequency domain resources for D2R transmission are 2*56+14+10=136 subcarriers.

[0257] (4.4): In the time-domain resource block divided by the first node, the subcarrier numbers are defined to increase by 1 sequentially from low frequency to high frequency. Assume that the first subcarrier number is 1, and so on. The generated ZC sequence is placed on the subcarriers with subcarrier numbers 62 to 75, and the correspondence between the ZC sequence and the device is saved for demodulation data.

[0258] (4.5): Use the time-frequency resource block obtained in the previous step to generate an OFDM signal and send it to the A-IoT device.

[0259] A-IoT device reflection process:

[0260] Users employ FSK modulation, where A-IoT devices transmit bits 1 and 0 by switching impedance at different frequencies. The impedance switching frequency here is the value sent to the A-IoT devices by the first node via R2D signaling; for example, an impedance switching frequency of N. 2,1 Δf indicates that bit 0 is transmitted, and the impedance switching frequency is N. 2,2 Δf indicates that bit 1 is being sent.

[0261] First node receiving process:

[0262] (5.1): Detect the backscattered signal in the frequency domain resources allocated in step two of the first node's transmission process, i.e., the frequency band detection signal corresponding to A-IoT operation. At a relative frequency domain sequence offset N... 1,1 Correlation is performed in the frequency domain using correlation sequences at each subcarrier offset frequency domain location to obtain the frequency domain correlation Y. 1,1 And so on, with a relative frequency domain sequence offset N... i,j Correlation is performed in the frequency domain using correlation sequences at each subcarrier offset frequency domain location to obtain the frequency domain correlation Y. i,j .

[0263] (5.2): For user one, compare the relevance Y 1,1 With Y 1,2 The size of Y 1,1 >Y 1,2 If the value is 0, it is considered that the A-IoT device is sending bit 0; otherwise, it is considered that the A-IoT device is sending bit 1.

[0264] For user two, the relevance Y is compared. 2,1 With Y 2,2 The size of Y 2,1 >Y 2,2 If the value is 0, it is considered that the A-IoT device is sending bit 0; otherwise, it is considered that the A-IoT device is sending bit 1.

[0265] Example 5: A-IoT devices communicate with the first node at different times:

[0266] This example considers two A-IoT devices communicating with the base station at two separate moments after being instructed by the first node. The first node continuously sends OFDM excitation signals for backscattering into the environment. When a device needs to access the network, it reflects the OFDM signals present in the environment to transmit data. The receiver receives the reflected signals, demodulates them, and completes the communication between the device and the first node.

[0267] For the first node, the first step is to determine the frequency domain sequence length L = 14 for backscatter transmission. A frequency domain sequence of length 14, such as the "gold" sequence, is generated and placed at the center of the frequency domain resources used for transmission. The subcarrier spacing Δf used in OFDM transmission is 15kHz. Next, based on the frequency domain sequence length L, the set of reflected transmission frequency offset parameters, including N, needs to be determined for the A-IoT device. 1,2 N 1,2 N 2,1 N 2,2 Four elements, of which N 1,1 N 1,2 N represents the frequency offset parameter used by the first device to communicate with the first node at time t1. 2,1 N 2,2 This refers to the frequency offset parameter used by the second device to communicate with the first node at time t2. Two subcarriers are reserved as a guard interval between each frequency band of the D2R signal, i.e., q = 2. To ensure that the frequencies in the reflected signal do not overlap, N... 1,1 N 1,2 N 2,1 The selection must satisfy min{|N 1,1 -N 1,2 |,|N 1,1 -N 2,1 |,|N1,2 -N 2,1 If |}≥L+q=16, then choose N. 1,1 =8, N 1,2 =24, N 2,1 =40, N 2,2 =56. At the initial time t0, the above parameters are sent to the device via R2D signaling. Afterwards, the first node generates an OFDM signal based on the frequency domain symbols determined above and continuously transmits it to the environment.

[0268] A-IoT devices receive the subcarrier spacing Δf and the frequency offset parameter N used for reflection via R2D signaling. 1,1 N 1,2 At moment t1, when the first A-IoT device needs to communicate with the first node, the device reflects the OFDM signal in the environment using the frequency offset parameter indicated by the first node to transmit the bit to be transmitted. When transmitting bit '1', the frequency shift distance is N. 1,1 Δf = 120kHz, when the A-IoT device transmits bit '0', the frequency shift distance is N. 1,2 Δf = 360kHz.

[0269] At time t2, another A-IoT device also needs to communicate with the first node; at the initial time t0, this device receives the subcarrier spacing Δf and the frequency offset parameter N for reflection via R2D signaling. 2,1 At time t2, the device uses the frequency offset parameter N indicated by the first node. 2,1 OFDM signals in the environment are reflected to transmit the bits to be transmitted. When transmitting bit '1', the frequency shift distance is N. 2,1 Δf = 600kHz, when the A-IoT device sends bit '0', the frequency shift distance is N. 2,2 Δf = 840kHz.

[0270] The first node receives signals by monitoring reflected signals on the allocated frequency band. When a reflected signal is detected, the base station performs correlation detection within the allocated frequency band using a predefined frequency domain sequence to decode (demodulate) the bit information transmitted by the A-IoT device.

[0271] In this embodiment, by adjusting the reflection coefficient of the A-IoT device, designing the frequency domain sequence, and placing the frequency domain sequence, the OFDM signal can be shifted in a specific direction in the frequency domain, thereby enabling the transmission and demodulation of backscattered information.

[0272] Furthermore, this application also provides an A-IoT device modulation method for OFDM signal FSK backscattering. A signal source generates a known OFDM signal. The A-IoT device adjusts a square wave with a reflection coefficient that is an integer multiple of the frequency of the two subcarrier intervals to cause a specific shift in the frequency domain symbol of the OFDM signal to transmit backscattering information. After the signal emitted by the signal source is reflected by the A-IoT device, two copies of the frequency domain sequence are generated at the corresponding positions of the transmitted bits, while no signal is present at the other position. The first node can use a ZC sequence with good autocorrelation performance to perform correlation at different positions in the frequency domain of the reflected signal, compare the magnitude of the correlation values, and thus determine the bit transmitted by the A-IoT device. Moreover, when the first node transmits the OFDM signal, the bandwidth of the frequency domain sequence must accommodate the total bandwidth of the signal reflected by the A-IoT device, and the length of the frequency domain sequence and the magnitude of the frequency shift caused by reflection must satisfy a certain relationship to ensure that the frequency domain sequences after reflection do not overlap.

[0273] Traditional backscattering frequency shifting schemes require A-IoT devices to completely shift the incident signal spectrum out of the original signal's frequency band. For broadband signals like OFDM, this requires shifting the incident signal spectrum by tens of megahertz, resulting in low spectrum resource utilization and making it difficult for A-IoT devices to implement. The solution in this application allows the incident and reflected signals to be in the same frequency band, achieving backscattering communication with frequency shift without completely shifting the incident signal out of its original band. This also reduces the manufacturing requirements for A-IoT devices and improves spectrum utilization.

[0274] Please see Figure 13 , Figure 13 This is a structural diagram of a communication device provided in an embodiment of this application. The communication device can be a first node, such as... Figure 13 As shown, it includes a memory 1320, a transceiver 1300, and a processor 1310:

[0275] Memory is used to store computer programs; transceiver is used to send and receive data under the control of the processor; processor is used to read the computer programs from memory and perform the following operations:

[0276] Send a first indication signal to the first A-IoT device, the first indication signal being used to instruct the first A-IoT device to frequency shift the first orthogonal frequency division multiplexing (OFDM) signal to obtain a second OFDM signal and then send the second OFDM signal;

[0277] The first indication signal carries at least one of the following:

[0278] Set of transmission frequency offset parameters;

[0279] A-IoT device modulation method;

[0280] Subcarrier spacing;

[0281] Transmission protection interval.

[0282] In some embodiments, the processor, for reading a computer program from memory, also performs at least one of the following:

[0283] The length of the frequency domain sequence is determined based on the set of transmission frequency offset parameters; or...

[0284] Obtain the length of the frequency domain sequence; based on the length of the frequency domain sequence, determine the set of transmission frequency offset parameters.

[0285] In some embodiments, the processor, for reading a computer program from memory, also performs the following operations:

[0286] Based on the transmission frequency offset parameter set and the frequency domain sequence length, the frequency domain resources used by the first node to receive the second OFDM signal are determined.

[0287] In some embodiments, the frequency domain resources include X subcarriers, where X is a value of 2*N. 1,1max +L+N′; where L is the length of the frequency domain sequence, N 1,1max N′ is the maximum frequency offset parameter in the set of transmission frequency offset parameters, N′ is the number of subcarriers occupied by the first guard interval, and N′ is an integer greater than or equal to 0.

[0288] In some embodiments, the processor, for reading a computer program in memory, further performs the following operations: determining a frequency domain sequence, the length of which is the length of the frequency domain sequence;

[0289] The processor, used to read computer programs from memory, also performs the following operations:

[0290] The second OFDM signal is detected in the frequency domain resources, and the second OFDM signal is demodulated based on the frequency domain sequence to obtain the received bit information.

[0291] In some embodiments, the processor is configured to read a computer program from memory and specifically perform the following operations:

[0292] The second OFDM signal is received at the first frequency position of the subcarrier offset by the first frequency offset parameter relative to the frequency domain sequence. The frequency correlation between the frequency domain sequence and the second OFDM signal received at the first frequency position is calculated to obtain the first correlation. The first frequency offset parameter is a parameter in the transmission frequency offset parameter set and is the frequency offset parameter used by the first A-IoT device when sending the first bit.

[0293] The second OFDM signal is received at the second frequency position of the subcarrier offset by the second frequency offset parameter relative to the frequency domain sequence. The frequency correlation between the frequency domain sequence and the second OFDM signal received at the second frequency position is calculated to obtain the second correlation. The second frequency offset parameter is a parameter in the transmission frequency offset parameter set and is the frequency offset parameter used by the first A-IoT device when sending the second bit.

[0294] The bit information is determined based on the first and second correlation scores.

[0295] In some embodiments, the total length of the transmission guard interval and the frequency domain sequence length is less than or equal to the target value, or the frequency domain sequence length is less than or equal to the target value;

[0296] The target value is either the first value or the minimum of the first and second values. The first value is the minimum difference between any two frequency offset parameters in the transmission frequency offset parameter set, and the second value is the minimum frequency offset parameter in the transmission frequency offset parameter set.

[0297] In some embodiments, the frequency offset of the second OFDM signal relative to the first OFDM signal is a positive integer multiple of the subcarrier spacing.

[0298] In some embodiments, the transmission frequency offset parameter set includes a frequency offset parameter corresponding to each of the at least one A-IoT devices, and the at least one A-IoT device includes a first A-IoT device;

[0299] The first indication signal also carries at least one of the following:

[0300] The time corresponding to each of the at least one A-IoT devices is used to instruct the A-IoT device to send a second OFDM signal at the time using the frequency offset parameter corresponding to the A-IoT device.

[0301] Among them, Figure 13In this context, the bus architecture can include any number of interconnected buses and bridges, specifically linking various circuits of one or more processors represented by processor 1310 and memory represented by memory 1320 together. The bus architecture can also link various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further herein. The bus interface provides an interface. The transceiver 1300 can be multiple components, including transmitters and receivers, providing a unit for communicating with various other devices over a transmission medium, including wireless channels, wired channels, optical fibers, etc. For different user equipment, the user interface 1330 can also be an interface capable of connecting external or internal devices, including but not limited to keypads, displays, speakers, microphones, joysticks, etc.

[0302] The processor 1310 is responsible for managing the bus architecture and general processing, and the memory 1320 can store the data used by the processor 1310 when performing operations.

[0303] Optionally, the processor 1310 can be a CPU (Central Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or CPLD (Complex Programmable Logic Device), and the processor can also adopt a multi-core architecture.

[0304] The processor executes any of the methods provided in the embodiments of this application by calling a computer program stored in memory, according to the obtained executable instructions. The processor and memory may also be physically separated.

[0305] It should be noted that the processor of the communication device provided in this application embodiment can implement the signal transmission method steps applied to the first node as implemented in the above method embodiment, and can achieve the same technical effect. Here, the parts and beneficial effects that are the same as those in the method embodiment will not be described in detail.

[0306] Please see Figure 14 , Figure 14 This is a structural diagram of a communication device provided in an embodiment of this application. The communication device can be a first A-IoT device, such as... Figure 14 As shown, it includes a memory 1420, a transceiver 1400, and a processor 1410:

[0307] Memory is used to store computer programs; transceiver is used to send and receive data under the control of the processor; processor is used to read the computer programs from memory and perform the following operations:

[0308] Receive the first indication signal sent by the first node;

[0309] Based on the first indication signal, the first OFDM signal is frequency-shifted to obtain the second OFDM signal;

[0310] Send the second OFDM signal to the first node;

[0311] The first indication signal carries at least one of the following:

[0312] Set of transmission frequency offset parameters;

[0313] A-IoT device modulation method;

[0314] Subcarrier spacing;

[0315] Transmission protection interval.

[0316] In some embodiments, the total length of the transmission guard interval and the frequency domain sequence length is less than or equal to the target value, or the frequency domain sequence length is less than or equal to the target value;

[0317] The target value is either the first value or the minimum of the first and second values. The first value is the minimum difference between any two frequency offset parameters in the transmission frequency offset parameter set, and the second value is the minimum frequency offset parameter in the transmission frequency offset parameter set.

[0318] In some embodiments, the frequency offset of the second OFDM signal relative to the first OFDM is a positive integer multiple of the subcarrier spacing.

[0319] In some embodiments, the transmission frequency offset parameter set includes a frequency offset parameter corresponding to each of the at least one A-IoT devices, and the at least one A-IoT device includes a first A-IoT device;

[0320] The first indication signal also carries at least one of the following:

[0321] At least one A-IoT device, each A-IoT device has a corresponding time, the time corresponding to the A-IoT device is used to instruct the A-IoT device to send a second OFDM signal at the time using the frequency offset parameter corresponding to the A-IoT device, and the time corresponding to the first A-IoT device is the first time;

[0322] Sending the second OFDM signal to the first node includes: sending the second OFDM signal to the first node at a first time.

[0323] Among them, Figure 14 In this context, the bus architecture can include any number of interconnected buses and bridges, specifically linking various circuits of one or more processors represented by processor 1410 and memory represented by memory 1420 together. The bus architecture can also link various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further herein. The bus interface provides an interface. The transceiver 1400 can be multiple components, including transmitters and receivers, providing a unit for communicating with various other devices over a transmission medium, including wireless channels, wired channels, optical fibers, etc. For different user equipment, the user interface 1430 can also be an interface capable of connecting external or internal devices, including but not limited to keypads, displays, speakers, microphones, joysticks, etc.

[0324] Processor 1410 is responsible for managing the bus architecture and general processing, while memory 1420 can store data used by processor 1410 when performing operations.

[0325] Optionally, the processor 1410 can be a CPU (Central Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or CPLD (Complex Programmable Logic Device), and the processor can also adopt a multi-core architecture.

[0326] The processor executes any of the methods provided in the embodiments of this application by calling a computer program stored in memory, according to the obtained executable instructions. The processor and memory may also be physically separated.

[0327] It should be noted that the processor of the communication device provided in this application embodiment can implement the signal transmission method steps applied to the first A-IoT device implemented in the above method embodiment, and can achieve the same technical effect. Here, the parts and beneficial effects that are the same as those in the method embodiment will not be described in detail.

[0328] Please see Figure 15 , Figure 15 This is a structural diagram of a signal transmission device (which can be applied to a first node) provided in an embodiment of this application, as shown below. Figure 15 As shown, the signal transmission device 1500 includes:

[0329] The first transmitting module 1501 is used to send a first indication signal to the first A-IoT device. The first indication signal is used to instruct the first A-IoT device to frequency shift the first orthogonal frequency division multiplexing (OFDM) signal to obtain a second OFDM signal and then transmit the second OFDM signal.

[0330] The first indication signal carries at least one of the following:

[0331] Set of transmission frequency offset parameters;

[0332] A-IoT device modulation method;

[0333] Subcarrier spacing;

[0334] Transmission protection interval.

[0335] In some embodiments, the device 1500 further includes at least one of the following:

[0336] The length determination module is used to determine the length of the frequency domain sequence based on the set of transmission frequency offset parameters; or,

[0337] The parameter set determination module is used to obtain the frequency domain sequence length and determine the transmission frequency offset parameter set based on the frequency domain sequence length.

[0338] In some embodiments, the device 1500 further includes:

[0339] The frequency domain resource determination module is used to determine the frequency domain resources for the first node to receive the second OFDM signal based on the transmission frequency offset parameter set and the frequency domain sequence length.

[0340] In some embodiments, the frequency domain resources include X subcarriers, where X is a value of 2*N. 1,1max +L+N′; where L is the length of the frequency domain sequence, N 1,1max N′ is the maximum frequency offset parameter in the set of transmission frequency offset parameters, N′ is the number of subcarriers occupied by the first guard interval, and N′ is an integer greater than or equal to 0.

[0341] In some embodiments, the device 1500 further includes:

[0342] The sequence determination module is used to determine the frequency domain sequence, and the length of the frequency domain sequence is the same as the length of the frequency domain sequence.

[0343] Device 1500 also includes:

[0344] The demodulation module is used to detect the second OFDM signal in the frequency domain and demodulate the second OFDM signal based on the frequency domain sequence to obtain the received bit information.

[0345] In some embodiments, the demodulation module includes:

[0346] The first correlation calculation unit is used to receive the second OFDM signal at the first frequency position of the subcarrier offset by the first frequency offset parameter relative to the frequency domain sequence, and to perform frequency correlation calculation on the frequency domain sequence and the second OFDM signal received at the first frequency position to obtain the first correlation. The first frequency offset parameter is a parameter in the transmission frequency offset parameter set, and is the frequency offset parameter used by the first A-IoT device when sending the first bit.

[0347] The second correlation calculation unit is used to receive the second OFDM signal at the second frequency position of the subcarrier offset by the second frequency offset parameter relative to the frequency domain sequence, and to perform frequency correlation calculation on the frequency domain sequence and the second OFDM signal received at the second frequency position to obtain the second correlation. The second frequency offset parameter is a parameter in the transmission frequency offset parameter set, and is the frequency offset parameter used by the first A-IoT device when sending the second bit.

[0348] The bit information determination module is used to determine bit information based on a first correlation and a second correlation.

[0349] In some embodiments, the total length of the transmission guard interval and the frequency domain sequence length is less than or equal to the target value, or the frequency domain sequence length is less than or equal to the target value;

[0350] The target value is either the first value or the minimum of the first and second values. The first value is the minimum difference between any two frequency offset parameters in the transmission frequency offset parameter set, and the second value is the minimum frequency offset parameter in the transmission frequency offset parameter set.

[0351] In some embodiments, the frequency offset of the second OFDM signal relative to the first OFDM signal is a positive integer multiple of the subcarrier spacing.

[0352] In some embodiments, the transmission frequency offset parameter set includes a frequency offset parameter corresponding to each of the at least one A-IoT devices, and the at least one A-IoT device includes a first A-IoT device;

[0353] The first indication signal also carries at least one of the following:

[0354] The time corresponding to each of the at least one A-IoT devices is used to instruct the A-IoT device to send a second OFDM signal at the time using the frequency offset parameter corresponding to the A-IoT device.

[0355] It should be noted that the signal transmission device provided in this application embodiment can implement the method steps applied to the first node as implemented in the above method embodiment, and can achieve the same technical effect. Here, the parts and beneficial effects that are the same as those in the method embodiment will not be described in detail.

[0356] Please see Figure 16 , Figure 16 This is a structural diagram of another signal transmission device (which can be applied to a first A-IoT device) provided in the embodiments of this application, as shown below. Figure 16 As shown, the signal transmission device 1600 includes:

[0357] The first receiving module 1601 is used to receive the first indication signal sent by the first node;

[0358] The frequency shift module 1602 is used to frequency shift the first OFDM signal based on the first indication signal to obtain the second OFDM signal;

[0359] The second transmitting module 1603 is used to transmit a second OFDM signal to the first node;

[0360] The first indication signal carries at least one of the following:

[0361] Set of transmission frequency offset parameters;

[0362] A-IoT device modulation method;

[0363] Subcarrier spacing;

[0364] Transmission protection interval.

[0365] In some embodiments, the total length of the transmission guard interval and the frequency domain sequence length is less than or equal to the target value, or the frequency domain sequence length is less than or equal to the target value;

[0366] The target value is either the first value or the minimum of the first and second values. The first value is the minimum difference between any two frequency offset parameters in the transmission frequency offset parameter set, and the second value is the minimum frequency offset parameter in the transmission frequency offset parameter set.

[0367] In some embodiments, the frequency offset of the second OFDM signal relative to the first OFDM is a positive integer multiple of the subcarrier spacing.

[0368] In some embodiments, the transmission frequency offset parameter set includes a frequency offset parameter corresponding to each of the at least one A-IoT devices, and the at least one A-IoT device includes a first A-IoT device;

[0369] The first indication signal also carries at least one of the following:

[0370] At least one A-IoT device, each A-IoT device has a corresponding time, the time corresponding to the A-IoT device is used to instruct the A-IoT device to send a second OFDM signal at the time using the frequency offset parameter corresponding to the A-IoT device, and the time corresponding to the first A-IoT device is the first time;

[0371] Sending the second OFDM signal to the first node includes: sending the second OFDM signal to the first node at a first time.

[0372] It should be noted that the signal transmission device provided in this application embodiment can implement the method steps applied to the first A-IoT device implemented in the above method embodiment, and can achieve the same technical effect. Here, the parts and beneficial effects that are the same as those in the method embodiment will not be described in detail.

[0373] This application provides a computer program product, including computer instructions, which, when executed by a processor, implement the steps of the signal transmission method described above. It achieves the same technical effects, and therefore, the parts and beneficial effects identical to those in the method embodiment will not be described in detail here.

[0374] It should be noted that the division of units in the embodiments of this application is illustrative and only represents one logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units described above can be implemented in hardware or as software functional units.

[0375] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a processor-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0376] This application provides a processor-readable storage medium storing a computer program. The computer program is used to cause the processor to execute the signal transmission method provided in this application embodiment, or the computer program is used to cause the processor to execute the signal transmission method provided in this application embodiment.

[0377] The processor-readable storage medium can be any available medium or data storage device that the processor can access, including but not limited to magnetic memory (e.g., floppy disk, hard disk, magnetic tape, magneto-optical disk (MO)), optical memory (e.g., CD, DVD, BD, HVD), and semiconductor memory (e.g., ROM, EPROM, EEPROM, non-volatile memory (NAND FLASH), solid-state drive (SSD)).

[0378] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0379] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer-executable instructions. These computer-executable instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0380] These processor-executable instructions may also be stored in a processor-readable memory that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the processor-readable memory produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0381] These processors can execute instructions that can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable device for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0382] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A signal transmission method, characterized in that, Applied to the first node, the method includes: Send a first indication signal to a first environmental Internet of Things (A-IoT) device, the first indication signal being used to instruct the first A-IoT device to frequency shift a first orthogonal frequency division multiplexing (OFDM) signal to obtain a second OFDM signal and then send the second OFDM signal; The first indication signal carries at least one of the following: Set of transmission frequency offset parameters; A-IoT device modulation method; Subcarrier spacing; Transmission protection interval.

2. The method according to claim 1, characterized in that, Before sending the first indication signal to the first environmental Internet of Things (A-IoT) device, the method further includes at least one of the following: The length of the frequency domain sequence is determined based on the set of transmission frequency offset parameters; or... Obtain the frequency domain sequence length; based on the frequency domain sequence length, determine the transmission frequency offset parameter set.

3. The method according to claim 2, characterized in that, The method further includes: Based on the transmission frequency offset parameter set and the frequency domain sequence length, the frequency domain resources used by the first node to receive the second OFDM signal are determined.

4. The method according to claim 3, characterized in that, The frequency domain resources include X subcarriers, where X is 2*N. 1,1max +L+N′; where L is the length of the frequency domain sequence, N 1,1max The maximum frequency offset parameter in the set of transmission frequency offset parameters, where N′ is the number of subcarriers occupied by the first guard interval, and N′ is an integer greater than or equal to 0.

5. The method according to claim 3, characterized in that, Before sending the first indication signal to the first environmental Internet of Things (A-IoT) device, the method further includes: determining a frequency domain sequence, wherein the length of the frequency domain sequence is the length of the frequency domain sequence. After determining the frequency domain resources for the first node to receive the second OFDM signal based on the transmission frequency offset parameter set and the frequency domain sequence length, the process includes: detecting the second OFDM signal on the frequency domain resources, and demodulating the second OFDM signal based on the frequency domain sequence to obtain the received bit information.

6. The method according to claim 5, characterized in that, The step of demodulating the second OFDM signal based on the frequency domain sequence to obtain the received bit information includes: The second OFDM signal is received at a first frequency position relative to the frequency domain sequence by a first frequency offset parameter of subcarriers. The frequency correlation between the frequency domain sequence and the second OFDM signal received at the first frequency position is calculated to obtain a first correlation. The first frequency offset parameter is a parameter in the transmission frequency offset parameter set and is the frequency offset parameter used by the first A-IoT device when sending the first bit. The second OFDM signal is received at a second frequency position relative to the frequency domain sequence by a second frequency offset parameter of subcarriers. The frequency correlation between the frequency domain sequence and the second OFDM signal received at the second frequency position is calculated to obtain a second correlation. The second frequency offset parameter is a parameter in the transmission frequency offset parameter set and is the frequency offset parameter used by the first A-IoT device when sending the second bit. The bit information is determined based on the first correlation and the second correlation.

7. The method according to claim 2, characterized in that, The total length of the transmission protection interval and the frequency domain sequence length is less than or equal to the target value, or the length of the frequency domain sequence is less than or equal to the target value; Wherein, the target value is a first value, or the minimum value between the first value and the second value; the first value is the minimum value of the difference between every two frequency offset parameters in the transmission frequency offset parameter set, and the second value is the minimum frequency offset parameter in the transmission frequency offset parameter set.

8. The method according to any one of claims 1-7, characterized in that, The frequency offset of the second OFDM signal relative to the first OFDM signal is a positive integer multiple of the subcarrier spacing.

9. The method according to any one of claims 1-7, characterized in that, The transmission frequency offset parameter set includes frequency offset parameters corresponding to each of at least one A-IoT device, and the at least one A-IoT device includes the first A-IoT device; The first indication signal also carries at least one of the following: The time corresponding to each of the at least one A-IoT devices is used to instruct the A-IoT device to send the second OFDM signal at that time using the frequency offset parameter corresponding to the A-IoT device.

10. A signal transmission method, characterized in that, Applied to the first A-IoT devices, including: Receive the first indication signal sent by the first node; Based on the first indication signal, the first OFDM signal is frequency-shifted to obtain the second OFDM signal; Send the second OFDM signal to the first node; The first indication signal carries at least one of the following: Set of transmission frequency offset parameters; A-IoT device modulation method; Subcarrier spacing; Transmission protection interval.

11. The method according to claim 10, characterized in that, The total length of the transmission protection interval and the frequency domain sequence length is less than or equal to the target value, or the length of the frequency domain sequence is less than or equal to the target value; Wherein, the target value is a first value, or the minimum value between the first value and the second value; the first value is the minimum value of the difference between every two frequency offset parameters in the transmission frequency offset parameter set, and the second value is the minimum frequency offset parameter in the transmission frequency offset parameter set.

12. The method according to claim 10, characterized in that, The frequency offset of the second OFDM signal relative to the first OFDM is a positive integer multiple of the subcarrier spacing.

13. The method according to claim 10, characterized in that, The transmission frequency offset parameter set includes frequency offset parameters corresponding to each of at least one A-IoT device, and the at least one A-IoT device includes the first A-IoT device; The first indication signal also carries at least one of the following: The time corresponding to each of the at least one A-IoT devices is used to instruct the A-IoT device to send the second OFDM signal using the frequency offset parameter corresponding to the A-IoT device at that time, and the time corresponding to the first A-IoT device is the first time; The step of sending the second OFDM signal to the first node includes: sending the second OFDM signal to the first node at the first time.

14. A communication device, characterized in that, include: Memory, transceiver, and processor, among which: The memory is used to store computer programs; the transceiver is used to send and receive data under the control of the processor; the processor is used to read the computer programs in the memory and execute the method according to any one of claims 1-9.

15. A communication device, characterized in that, include: A memory, a transceiver, and a processor, wherein: the memory is used to store a computer program; the transceiver is used to send and receive data under the control of the processor; and the processor is used to read the computer program in the memory and execute the method of any one of claims 10-13.

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