Signal transmission method and apparatus, communication device, and readable storage medium

Abstract

The present application relates to the technical field of communications, and discloses a signal transmission method and apparatus, a communication device, and a readable storage medium. The signal transmission method in embodiments of the present application comprises: a first device performing backscatter modulation on the basis of an information bit to be transmitted and a second signal, so as to obtain a first signal, wherein the second signal is a carrier signal of the first signal, the first signal comprises at least one first signal unit, each first signal unit comprises two chirp spread spectrum (CSS) symbols, the average powers or reflection coefficients of the two CSS symbols are different, the parameters of the two CSS symbols other than the average power and the reflection coefficient are the same, and said information bit is modulated by means of the frequency of each CSS symbol in each first signal unit; and sending the first signal.

Description

Signal transmission method and device, communication device, and readable storage medium

[0001] Cross-reference to Related Applications

[0002] The present application claims priority to the Chinese patent application No. 202410835677.0 filed on June 26, 2024 in China, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application belongs to the field of communication technology, and particularly relates to a signal transmission method and device, a communication device, and a readable storage medium. BACKGROUND

[0004] Chirp spread spectrum (CSS) modulation mainly uses a linear frequency modulation signal to carry information bits. Since CSS modulation has good transmission coverage and transmission reliability, the CSS modulation is applied to a backscatter communication system in the related art. In the backscatter CSS modulation system based on a CSS signal, a reader device of a bistatic architecture not only receives a backscatter CSS modulation signal sent from a backscatter device, but also receives a CSS signal sent from an excitation source device. Since the frequency of the useful backscatter CSS modulation signal received by the reader device and the frequency of the CSS signal sent from the excitation source device are almost close, and the frequency of the CSS signal is linearly changed, the reader device has great difficulty in eliminating the interference of the CSS signal when demodulating, thereby causing the CSS signal interference to be unable to be effectively eliminated. SUMMARY

[0005] Embodiments of the present application provide a signal transmission method and device, a communication device, and a readable storage medium, which can solve the problem that the CSS signal interference cannot be effectively eliminated in the related art.

[0006] In a first aspect, a signal transmission method is provided, which is performed by a first device, and the method comprises: performing backscatter modulation on information bits to be transmitted and a second signal to obtain a first signal by the first device, wherein the second signal is a carrier signal of the first signal; the first signal comprises at least one first signal unit, each first signal unit comprises two CSS (Chirp Spread Spectrum) symbols, the average power or the reflection coefficient of the two CSS symbols is different, the other parameters of the two CSS symbols are the same, the information bits to be transmitted are modulated by the frequency of each CSS symbol in each first signal unit; and the first device sends the first signal.

[0007] In a second aspect, a signal transmission method is provided, which is performed by a second device and includes: receiving, by the second device, a first signal transmitted by a first device; wherein the first signal is obtained by backscatter modulation of information bits to be transmitted and a second signal, the second signal being a carrier signal of the first signal; the first signal includes at least one first signal unit, each first signal unit including two CSS symbols, the two CSS symbols being different in average power or reflection coefficient, the two CSS symbols being the same in other parameters except the average power and the reflection coefficient, and the information bits to be transmitted being modulated by the frequency of each CSS symbol in each first signal unit; performing, by the second device, a subtraction operation on the two CSS symbols in the first signal unit of the first signal to obtain a third signal; and demodulating, by the second device, the third signal to obtain the information bits to be transmitted.

[0008] In a third aspect, a signal transmission apparatus is provided, which is applied to a first device and includes: a modulation module configured to modulate, by the first device, a first signal according to information bits to be transmitted and a second signal, the second signal being a carrier signal of the first signal; the first signal including at least one first signal unit, each first signal unit including two CSS symbols, the two CSS symbols being different in average power or reflection coefficient, the two CSS symbols being the same in other parameters except the average power and the reflection coefficient, and the information bits to be transmitted being modulated by the frequency of each CSS symbol in each first signal unit; and a transmission module configured to transmit the first signal.

[0009] In a fourth aspect, a signal transmission apparatus is provided, which is applied to a second device and includes: a second receiving module configured to receive a first signal transmitted by a first device; wherein the first signal is obtained by backscatter modulation of information bits to be transmitted and a second signal, the second signal being a carrier signal of the first signal; the first signal including at least one first signal unit, each first signal unit including two CSS symbols, the two CSS symbols being different in average power or reflection coefficient, the two CSS symbols being the same in other parameters except the average power and the reflection coefficient, and the information bits to be transmitted being modulated by the frequency of each CSS symbol in each first signal unit; a calculation module configured to perform a subtraction operation on the two CSS symbols in the first signal unit of the first signal to obtain a third signal; and a demodulation module configured to demodulate the third signal to obtain the information bits to be transmitted.

[0010] In a fifth aspect, a signal transmission apparatus is provided, which is configured to perform the steps of the method according to the first aspect, or perform the steps of the method according to the second aspect.

[0011] In a sixth aspect, a communication device is provided, which comprises a processor and a memory, the memory storing programs or instructions executable on the processor, the programs or instructions being executed by the processor to implement the steps of the method according to the first aspect, or implement the steps of the method according to the second aspect.

[0012] In a seventh aspect, a communication device is provided, which comprises a processor and a communication interface, when the communication device is a first device, the processor is configured to modulate a first signal according to information bits to be transmitted and a second signal, and the communication interface is configured to transmit the first signal; or when the communication device is a second device, the communication interface is configured to receive a first signal transmitted by a first device, the first signal being modulated according to information bits to be transmitted and a second signal, and the processor is configured to subtract two CSS symbols in a first signal unit of the first signal to obtain a third signal, and demodulate the third signal to obtain the information bits to be transmitted; wherein the second signal is a carrier signal of the first signal; the first signal comprises at least one first signal unit, each first signal unit comprises two CSS symbols, the average power or reflection coefficient of the two CSS symbols is different, and other parameters of the two CSS symbols are the same, and the information bits to be transmitted are modulated by the frequency of each CSS symbol in each first signal unit.

[0013] In an eighth aspect, a readable storage medium is provided, which stores programs or instructions, the programs or instructions being executed by a processor to implement the steps of the method according to the first aspect, or implement the steps of the method according to the second aspect.

[0014] In a ninth aspect, a wireless communication system is provided, which comprises a first device and a second device, the first device being configured to perform the steps of the method according to the first aspect, and the second device being configured to perform the steps of the method according to the second aspect.

[0015] In a tenth aspect, a chip is provided, which comprises a processor and a communication interface, the communication interface being coupled to the processor, and the processor being configured to run programs or instructions to implement the steps of the method according to the first aspect, or implement the steps of the method according to the second aspect.

[0016] In a eleventh aspect, a computer program / program product is provided, which is stored in a storage medium, and is executed by at least one processor to implement the steps of the method according to the first aspect, or to implement the steps of the method according to the second aspect.

[0017] By the scheme in the embodiments of the present application, the first signal, i.e., the backscattering CSS signal, has a repetitive structure, i.e., the information bits to be transmitted are modulated by the frequency of each CSS symbol in the first signal, so that when signal demodulation is performed at the receiving end, the CSS signal interference can be eliminated by means of a subtraction operation, thereby effectively eliminating the CSS signal interference. BRIEF DESCRIPTION OF DRAWINGS

[0018] FIG. 1A, FIG. 1B, FIG. 1C, FIG. 1D and FIG. 1E are schematic diagrams of a backscattering-based communication architecture in the embodiments of the present application;

[0019] FIG. 2A is a schematic diagram of a frequency uplink mode of CSS modulation in the embodiments of the present application;

[0020] FIG. 2B is a schematic diagram of a frequency downlink mode of CSS modulation in the embodiments of the present application;

[0021] FIG. 2C is a schematic diagram of a CSS modulation mode in the embodiments of the present application;

[0022] FIG. 3 is a flowchart of a signal transmission method provided in the embodiments of the present application;

[0023] FIG. 4 is a flowchart of another signal transmission method provided in the embodiments of the present application;

[0024] FIG. 5A and FIG. 5B are schematic diagrams of a centralized frame structure in the first embodiment of the present application;

[0025] FIG. 6A and FIG. 6B are schematic diagrams of a distributed frame structure in the first embodiment of the present application;

[0026] FIG. 7 is a schematic diagram of a LoRa frame structure in the first embodiment of the present application;

[0027] FIG. 8A, FIG. 8B and FIG. 8C are schematic diagrams of signals related to a modulation scheme in the second embodiment of the present application;

[0028] FIG. 9A, FIG. 9B and FIG. 9C are schematic diagrams of signals related to a modulation scheme in the second embodiment of the present application;

[0029] FIG. 10 is a schematic diagram of a demodulation scheme in the third embodiment of the present application;

[0030] FIG. 11 is a schematic diagram of a structure of a signal transmission apparatus provided in the embodiments of the present application;

[0031] FIG. 12 is a structural schematic diagram of another signal transmission device according to an embodiment of the present application;

[0032] FIG. 13 is a structural schematic diagram of a communication device according to an embodiment of the present application. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present application will be clearly described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0034] The terms "first", "second", and the like in the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second" are generally a category and do not limit the number of objects, for example, the first object can be one or more. In addition, "or" in the present application means at least one of the connected objects. For example, the protection scope of "A or B" at least covers three schemes, namely, scheme one: including A and not including B; scheme two: including B and not including A; scheme three: including A and including B. In addition, the terms "A and / or B", "at least one of A and B", "at least one of A or B" also at least cover the above three schemes, respectively. The character " / " generally represents that the objects before and after are in an "or" relationship.

[0035] The term "indication" in the present application can be a direct indication (or explicit indication) or an indirect indication (or implicit indication). The direct indication can be understood as that the sender explicitly informs the receiver of the specific information, the operation to be performed or the request result, etc. in the indication sent by the sender. The indirect indication can be understood as that the receiver determines the corresponding information according to the indication sent by the sender, or judges and determines the operation to be performed or the request result, etc. according to the judgment result.

[0036] It is worth noting that the technology described in the embodiments of the present application is not limited to Long Term Evolution (LTE) / LTE-Advanced (LTE-A) systems, but can also be used in other wireless communication systems, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single-carrier Frequency-Division Multiple Access (SC-FDMA) or other systems. The terms "system" and "network" in the embodiments of the present application are often used interchangeably, and the described technology can be used in the above-mentioned systems and radio technologies, as well as other systems and radio technologies. The following description describes a New Radio (NR) system for example purposes, and NR terminology is used in most of the following description, but these technologies can also be applied to systems other than NR systems, such as 6th Generation (6G) communication systems. th

[0037] In order to facilitate understanding of the embodiments of the present application, the following is first described.

[0038] Backscatter Communication (BSC) refers to a backscatter communication device using radio frequency signals in other devices or environments for signal modulation to transmit its own information, which is a typical passive Internet of Things device. The basic constituent modules and main functions of the backscatter communication sending end include:

[0039] Antenna unit: used for receiving radio frequency signals, control commands, and at the same time for sending modulated backscatter signals.

[0040] Energy harvesting module or power supply module: this module is used for radio frequency energy harvesting of the backscatter communication device, or other energy harvesting, including but not limited to solar energy, kinetic energy, mechanical energy, thermal energy, etc. In addition to including an energy harvesting module, a battery power supply module can also be included, in which case the backscatter communication device is a semi-passive device. The energy harvesting module or power supply module supplies power to all other modules in the device.

[0041] ​Microcontroller: including controlling baseband signal processing, energy storage or data scheduling state, switch switching, system synchronization, etc.

[0042] Signal receiving module: for demodulating control commands or data, etc. sent by the reverse scattering communication receiving end or other network nodes.

[0043] Encoding and modulation module: channel encoding and signal modulation are carried out under the control of the controller, and modulation is realized by selecting different load impedances under the control of the controller through the selection switch.

[0044] Memory or sensing module: for storing identification ID information, location information or sensing data, etc. of the device.

[0045] In addition to the above typical constituent modules, the future reverse scattering communication sending end can also integrate tunnel diode amplifier module, low noise amplifier module, etc. to improve the receiving sensitivity and transmission power of the sending end.

[0046] Optionally, the basic constituent modules and main functions of the reverse scattering communication receiving end include:

[0047] Antenna unit: for receiving modulated reverse scattering signals.

[0048] Reverse scattering signal detection module: for detecting reverse scattering signals sent by the reverse scattering communication sending end, including but not limited to ASK detection, PSK detection, FSK detection or QAM detection, etc.

[0049] Demodulation and decoding module: demodulating and decoding the detected signals to recover the original information stream.

[0050] The reverse scattering communication device controls the reflection coefficient Γ of the modulation circuit by adjusting its internal impedance, thereby changing the amplitude, frequency, phase, etc. of the incident signal, realizing the modulation of the signal. The reflection coefficient Γ can be represented as:

[0051] Where Z0 is the characteristic impedance of the antenna; Z1 is the load impedance; j represents a complex number, θ T represents the phase. Assuming that the incident signal is represented as S in (t), then the output signal is Therefore, by properly controlling the reflection coefficient, corresponding amplitude modulation, frequency modulation or phase modulation can be achieved. Based on this, the backscatter communication device can be a tag in a traditional radio frequency identification (RFID), or a passive or semi-passive Internet of Things (IoT) device. Here, the backscatter communication device can be collectively referred to as a BSC device.

[0052] In an implementation, according to the tag capability and the source of the capability, the tag can be divided into: Device A: the tag is a passive tag, without energy storage capacitor / battery, relying on radio frequency (RF) signal for energy supply, the received RF signal is the power signal of the rectifier, without carrier generation capability, relying on RF as a radio frequency carrier for backscatter communication transmission, with the lowest power consumption; Device B: the tag is a semi-passive tag, with energy storage capacitor / battery, relying on non-RF signal for energy supply, optionally, with PA / LNA or other active devices, without carrier generation capability, relying on RF as a radio frequency carrier for backscatter communication transmission, with the second lowest power consumption; Device C: the tag is an active tag, with energy storage capacitor / battery, relying on non-RF signal for energy supply, with carrier generation capability, with the highest power consumption.

[0053] Optionally, the backscatter-based communication architecture can include at least the following modes:

[0054] (1) Topology structure Topology 1: as shown in FIG. 1A, the base station in Topology 1 is both a radio frequency source or a transmitting device and a receiving device, so Topology 1 is a monostatic backscatter communication system (MBCS) architecture. The traditional RFID system is a typical MBCS, which contains an ambient IoT device (such as a tag) and a reader (such as a base station) for energy supply, and the tag directly communicates with the reader, and the reader can have a frequency division duplexing (FDD) function module. In Topology 1, the transmitting device of the control signaling and the receiving device of the backscatter signal are the same device, and the transmitting device of the RF carrier source can be the same device as the aforementioned device, or can be an independent device.

[0055] (2) Topology 2: As shown in FIG. IB, in Topology 2, the Ambient IoT Device (e.g., Tag) receives control signaling and carrier signals transmitted by an intermediate node, which can be a User Equipment (UE), a repeater, an IAB node, etc., instructed by a network device (e.g., a base station gNB). The intermediate node can also forward IoT data to the gNB as a relay.

[0056] (3) Topology 3: Topology 3 involves a bistatic backscatter communication system (BBCS), in which the radio frequency source, the BSC transmitting device, and the BSC receiving device are separate; in Topology 3, the Ambient IoT Device (e.g., Tag) transmits IoT data / uplink signaling to a base station and receives data / signaling transmitted by an auxiliary node, as shown in FIG. 1C, or transmits IoT data / uplink signaling to an auxiliary node and receives data / signaling transmitted by a base station, as shown in FIG. ID; the base station and the auxiliary node communicate through a Uu interface, and the auxiliary node can be a UE, a repeater, an IAB, etc.

[0057] (4) Topology 4: As shown in FIG. IE, in Topology 4, a UE serves as a Reader to communicate with a Tag. This architecture also belongs to a monostatic backscatter communication architecture, with the difference being that the Reader is a UE rather than a base station.

[0058] Chirp modulation, or Chirp spread spectrum (CSS) modulation, mainly uses a linear frequency modulation signal to carry information bits. Specifically, a CSS modulation signal can be divided into an up-chirp mode (as shown in FIG. 2A) and a down-chirp mode (as shown in FIG. 2B). When using the up-chirp mode, the frequency of the CSS modulation signal increases over time; when using the down-chirp mode, the frequency of the CSS modulation signal decreases over time. However, the frequency of the CSS modulation signal is periodically changed between a low frequency f1 and a high frequency f2 along a certain rule, with a sweep bandwidth of BW = f2 - f1, a sweep time of T s , and a sweep slope of If the Chirp signal is expressed as a baseband signal, the up-chirp signal and the down-chirp signal can be expressed as:

[0059] The two chirp signals described above, whether in up-chirp mode or down-chirp mode, cannot directly transmit information bits. Therefore, the CSS modulation actually realizes different information transmission by changing the initial frequency of the pilot. Since the initial frequency of the scan is changed, the linear increase in frequency during the entire signal scanning period will exceed the specified scan termination frequency f2 or f1. At this time, the CSS modulation specifies that once the scanning frequency exceeds the upper limit frequency f2 or the lower limit frequency f1 of the scan, the subsequent scanning frequency is directly reduced by BW or the subsequent scanning frequency is directly increased by BW.

[0060] In combination with the parameters of the CSS modulation, several important parameters are defined, such as the spreading factor (Spreading Factor, SF), the chip (chirp), and the symbol rate / chip rate, which are described as follows.

[0061] (1) Spreading factor SF:

[0062] The spreading factor represents the number of information bits contained in each symbol, that is, 1 symbol is spread to 2 SF chips for transmission, and different symbols are also mapped to different CSS modulation initial frequencies. Taking SF = 2 as an example, a symbol can contain at most 2 2 bits, and can represent 2 SF = 4 values, such as 0-3, and the number of chips is 4. Taking the up-chirp mode as an example, the frequency range that can be changed in a frequency rising period can be divided into 2 c chips.

[0063] (2) Chirp rate, or symbol rate:

[0064] The chirp rate is the transmission rate of each chip, which can be represented as: R SF = BW

[0065] The transmission time of each chip is:

[0066] Since each CSS symbol has 2 SF chips, the transmission time of the symbol is:

[0067] Based on the above definitions, the slope of the linear frequency increase in the CSS modulation is:

[0068] Referring to FIG. 2C, four symbols of the CSS modulation are given taking SF = 2 as an example. Among them, the starting frequency of symbol 1 is f1, and the linear frequency increases to f2, representing bits 00; the starting frequency of symbol 2 is and linearly increases to f2, and then linearly increases to representing bit 01; the starting frequency of symbol 3 is and linearly increases to f2, and then linearly increases to representing bit 10; the starting frequency of symbol 4 is and linearly increases to f2, and then linearly increases to representing bit 11. Thus, if the starting frequency of the corresponding symbol can be demodulated, and the mapping of the starting frequency to the symbol is known, the input bit before CSS modulation can be obtained.

[0069] In the corresponding demodulation process, a reference Chirp signal opposite to the CSS modulation mode can be used for mixing, and the input bit can be finally demodulated by Fast Fourier Transform (FFT) calculation. For example, if the up-chirp signal with linearly increasing frequency from f1 to f2 is used for CSS modulation, a down-chirp signal with linearly decreasing frequency from f2 to f1 is used for mixing at the receiving end.

[0070] Suppose the CSS modulation is performed by using the up-chirp mode, the baseband signal can be expressed as:

[0071] where f0 is the initial frequency, represents the slope of linear increase. For the reference up-chirp signal, For simplicity, the reference up-chirp signal can be denoted as:

[0072] The CSS modulation signal can be a frequency cyclic shift of the reference up-chirp signal, which can be expressed as: n ) = c(t; f n ) w(t; 0, t n ) + c(t; f n -BW) w(t; t n , T)

[0073] where f0 is the initial frequency, is the starting frequency of the CSS modulation symbol, w(t; t a , t b ) is a rectangular window function, which can be expressed as:

[0074] Therefore, for a CSS modulation symbol carrying SF bits, there are 2 SF optional starting frequency points.

[0075] In the receiving end, the receiving end identifies the frequency point peak position in the frequency domain by utilizing the reference down-chirp signal c * (t) first performing mixing or de-chirp processing, such as processing by using the following formula:

[0076] After mixing to obtain s ′ (t;f n ), the receiving end further performs FFT calculation, and identifies the frequency point peak position in the frequency domain and finally performs input bit decision.

[0077] Optionally, the scheme in the present application can be applied to LTE systems, 5G NR systems, and NR evolution systems such as 6G systems and 6G evolution systems, IEEE 802.11 systems (such as WiFi systems), Bluetooth systems, LoRa systems, Zigbee systems, LP-WUS / WUR systems, backscatter communication systems, low-power Internet of Things systems, Ambient IoT communication systems, and the like.

[0078] The signal transmission method, device, communication device, and readable storage medium provided in the embodiments of the present application will be described in detail below in combination with the accompanying drawings and some embodiments and application scenarios thereof.

[0079] Please refer to FIG. 3, which is a flowchart of a signal transmission method provided in an embodiment of the present application, the method being performed by a first device such as a backscatter device; as shown in FIG. 3, the method comprises the following steps:

[0080] Step 31: The first device modulates a second signal according to information bits to be transmitted by backscattering, to obtain a first signal;

[0081] Step 32: The first device transmits the first signal.

[0082] In the embodiments of the present application, the second signal is a carrier signal of the first signal, and the first signal is a backscattering modulation signal of the second signal. The first signal comprises at least one first signal unit, each first signal unit comprising two CSS symbols, such as two adjacent CSS symbols; the average power or reflection coefficient of the two CSS symbols is different, and other parameters of the two CSS symbols are the same, and the information bits to be transmitted are modulated by the frequency of each CSS symbol in each first signal unit.

[0083] Optionally, the other parameters at least include the following: a sweep mode; a lowest sweep frequency; a highest sweep frequency; a sweep start frequency; a sweep end frequency; a center frequency; a bandwidth; a spreading factor; a code rate; a symbol rate; and the like.

[0084] Optionally, the waveform form of the second signal can be set based on actual requirements, as long as the second signal can obtain the first signal with a repetitive structure in the scheme of the present application.

[0085] Optionally, the scheme in the embodiments of the present application can be applied to different Ambient IoT topologies, such as the topologies shown in FIG. 1B, FIG. 1C, and the like.

[0086] Through the scheme in the embodiments of the present application, the first signal, i.e., the backscattering CSS signal, has a repetitive structure, i.e., the information bits to be transmitted are modulated by the frequency of each CSS symbol in the first signal, so that when signal demodulation is performed at the receiving end, the CSS signal interference can be eliminated by means of a subtraction operation, thereby effectively eliminating the CSS signal interference.

[0087] Optionally, the second signal includes at least one second signal unit, each second signal unit including two CSS symbols or two reference Chirp symbols with the same parameters; the first signal is obtained by adding a first part and a second part, the first part being a signal obtained by performing frequency shift and filtering on the second signal at a first frequency, and the second part being a signal obtained by performing frequency shift and filtering on the second signal at a second frequency; the frequency shift directions of the first part and the second part are opposite, and the sum of the first frequency and the second frequency is equal to the bandwidth size of the CSS symbol (or signal) or the reference Chirp symbol (or signal) in the second signal, the first frequency and the second frequency being a frequency pair for frequency shift associated with the information bits to be transmitted. The opposite frequency shift directions can be one positive direction frequency shift and the other negative direction frequency shift, for example: if the first frequency is f 2m-1 and the second frequency is f 2m , then the second signal can be frequency shifted by f 2m-1 (i.e., in the positive direction), and the second signal can be frequency shifted by -f 2m (i.e., in the negative direction); or, the second signal can be frequency shifted by -f 2m-1 (i.e., in the negative direction), and the second signal can be frequency shifted by f 2m (i.e., in the positive direction).

[0088] Thus, on one hand, the interference of the CSS carrier signal can be eliminated by utilizing the repetitive structure of the backscattered CSS signal (i.e., the first signal); on the other hand, by performing frequency shift and filtering on each CSS symbol in association with the frequency pair of the information bits to be transmitted, the generated signal can satisfy the Chirp signal characteristic of the CSS signal, so as to achieve a farther transmission coverage or transmission reliability by utilizing the transmission characteristic of the CSS signal.

[0089] Optionally, the filtering can be a filtering with a center frequency f0 and a bandwidth interval BW, where the f0 is a center frequency of a CSS signal or a reference Chirp signal in the second signal, i.e., the f0 is a center frequency of the second signal; and the BW is a bandwidth of a CSS symbol or a reference Chirp symbol in the second signal, i.e., the BW is a bandwidth of the second signal.

[0090] Optionally, the second signal can satisfy at least one of the following:

[0091] The average power of the two CSS symbols in each second signal unit is the same, or the average power of the two reference Chirp symbols in each second signal unit is the same;

[0092] The time interval between two adjacent second signal units in the second signal is greater than or equal to 0.

[0093] In an optional implementation, the second signal S(t) is a radio frequency carrier signal of the first signal C(t), and at least the following characteristics can be satisfied:

[0094] (a) One signal unit in S(t) includes two CSS symbols or reference Chirp symbols with the same parameters:

[0095] (b) The length of one signal unit in S(t) is equal to 2T time units; the time unit can be a protocol-defined unit such as a symbol, a time slot, a subframe, a frame, etc., or a time unit such as a microsecond, a millisecond, a minute, etc. s

[0096] (c) The parameters of the CSS symbol S1(t) can at least include the following:

[0097] (I) a center frequency f0;

[0098] (II) a bandwidth BW;

[0099] (III) a spreading factor SF;

[0100] (IV) a symbol length

[0101] ​​(IIV) frequency linear growth slope or

[0102] (IIIV) the starting swept frequency f of each symbol start ;

[0103] (V) the average power of each symbol; here the same average power is set, which can be used to ensure that the radio frequency interference will be eliminated after the subtraction of the two CSS symbols in the first signal;

[0104] (d) the CSS symbol S1(t) can be expressed as:

[0105] (e) the basic time unit interval between each signal unit in the second signal S(t) is T g ≥ 0.

[0106] In another optional implementation, the first signal C(t) is a backscattering signal generated based on the second signal S(t), and at least the following characteristics are met:

[0107] (a) two CSS symbols C 1,n (t) with different average powers or reflection coefficients are included in one signal unit of the first signal C(t), and the nth signal unit satisfies:

[0108] (b) the CSS symbol C 1,n (t) at least meets the following characteristics:

[0109] (I) is composed of the sum of a first part and a second part :

[0110] (II) the first part is a signal generated by shifting the S1(t) in the second signal by f 2m-1 (0≤f 2m-1 ≤BW, m ∈ {1, 2, …, M}) and performing filtering with a center frequency f0 and a bandwidth interval :

[0111] (III) the second part is a signal generated by shifting the S1(t) in the second signal by -f 2m (0≤f 2m ≤BW, m ∈ {1, 2, …, M}) and performing filtering with a center frequency f0 and a bandwidth interval :

[0112] As described above: 1) represents filtering of the signal with a center frequency f0and a bandwidth interval ; 2) m is the log2 M-bit information bit of the m-th input, m e {1, …, M}; the mapping relationship between m and the log2 M-bit information bit can be pre-configured by the network or protocol, and the mapping mode can be one of Gray mapping, natural mapping, Contourwise-Gray mapping, etc.; 3) f 2m-1 +f 2m = BW, m e {1, 2, …, M}; and when k ≠ m, f 2m-1 ≠ f 2k-1 , f 2m ≠ f 2k .

[0113] (c) The characteristic of the CSS symbol C 1,n (t-T s ) is that C 1,n (t-T s ) is a signal after the delay T 1,n of C s (t), or C 1,n (t-T s ) is a repetition of the signal C 1,n (t) in the next symbol period T s ;

[0114] (d) β1and β2are respectively the reflection coefficient or the average power of the two CSS symbols in the signal unit; and β1≠ β2, so as to ensure that the third signal constructed subsequently is effective;

[0115] (e) One signal unit transmission of the first signal can carry log2 M (log2 M ≤ SF) information bits;

[0116] (f) The length of one signal unit is 2T s time units;

[0117] (g) The following parameters of the first signal and the second signal are the same:

[0118] (I) Bandwidth BW;

[0119] (II) Spreading factor SF;

[0120] (III) Frequency linear growth slope

[0121] (IV) Symbol period

[0122] In the embodiments of the present application, the first device can modulate a signal according to configured or indicated information. The above-mentioned obtaining the first signal by backscatter modulating the to-be-transmitted information bits and the second signal according to the to-be-transmitted information bits and the second signal can include:

[0123] The first device backscatter modulates the to-be-transmitted information bits and the second signal according to the obtained first information to obtain the first signal; the first information is information related to signal modulation, and the first information can include but is not limited to at least one of the following:

[0124] (a) a frequency value contained in a frequency pair for frequency shift associated with the to-be-transmitted information bits; in this way, the frequency value contained in the frequency pair for frequency shift associated with the to-be-transmitted information bits can be directly determined according to the to-be-transmitted information bits;

[0125] (b) a size of a physical resource block (PRB), a resource block group (RBG), and / or a bandwidth part (BWP) of a frequency pair for frequency shift associated with the to-be-transmitted information bits; in this way, the frequency value contained in the frequency pair for frequency shift can be indirectly determined based on the size of the PRB\RGB\BWP configured or indicated;

[0126] (c) a modulation mode of the first signal, such as but not limited to FSK-CSS modulation, binary on-off keying (OOK) modulation, amplitude shift keying (ASK) modulation, phase shift keying (PSK) modulation, frequency shift keying (FSK) modulation, quadrature amplitude modulation (QAM), amplitude phase shift keying (APSK) modulation, etc.;

[0127] (d) a modulation order of the first signal, such as the modulation order being M;

[0128] (e) a modulation rate or a backscatter link frequency (BLF) of the first signal;

[0129] (f) an encoding mode of the first signal, such as but not limited to a channel encoding mode, a line encoding mode, and the like; the channel encoding mode is such as Reed-Solomon codes (RS codes), Polar codes, convolutional codes, repetition codes, and the like; the line encoding mode is such as FM0 encoding, Miller codes, Manchester codes, and the like; based on the encoding mode, the first device can generate a corresponding first signal;

[0130] (g) an encoding code rate of the first signal;

[0131] (h) a reflection coefficient or a reflection signal amplification coefficient of the first signal, such as an average power of two CSS symbols in a first signal unit of the first signal or a reflection coefficient;

[0132] (i) first index information associated with a modulation and encoding of the first signal, the first index information being used to indicate an associated modulation and encoding parameter; different first index information corresponds to different modulation and encoding parameters, and each first index information can correspond to a set of modulation and encoding parameters (as described in (a) to (h) above), and a corresponding relationship can be preconfigured by a network or a protocol. With the first index information, the first device can obtain the associated modulation and encoding parameter, and thus generate a corresponding backscattering modulation signal (i.e., the first signal).

[0133] In the embodiments of the present application, the first device can transmit the first signal according to the configured or indicated information. The above-mentioned transmitting the first signal can include:

[0134] The first device transmits the first signal according to the obtained second information; the second information is information related to transmission of the first signal, and the second information can include but is not limited to at least one of the following: a transmission power of the first signal; a preamble or synchronization sequence of the first signal; a reference signal of the first signal, which can be used to estimate a channel or time-frequency information in the first signal; time domain resource information of the first signal, such as including a number of repeated transmissions of the signal, a signal period, time slot configuration information, subframe information, and the like; frequency domain resource information of the first signal, such as including frequency, bandwidth, and the like; spatial domain resource information of the first signal, such as including antenna, code word, layer, antenna port, and the like.

[0135] In the embodiments of the present application, the first device can be configured or indicated with relevant information for receiving a carrier signal. The above-mentioned signal transmission method can further include: the first device receives the second signal according to the obtained third information; the third information can include but is not limited to at least one of the following:

[0136] a frequency domain related parameter of the second signal;

[0137] a time domain related parameter of the second signal;

[0138] a signal waveform and a frame structure of the second signal;

[0139] a baseband signal parameter of the second signal;

[0140] second index information associated with the signal parameter of the second signal, the second index information being used to indicate the associated carrier signal parameter; wherein different second index information corresponds to different signal parameters of the second signal, and each second index information can correspond to a set of carrier signal parameters, such as a frequency domain related parameter, a time domain related parameter, and / or a signal waveform, and the corresponding relationship can be pre-configured by a network or a protocol. With the second index information, the first device can obtain the signal parameter of the associated second signal, thereby accurately receiving the second signal.

[0141] It should be noted that the second signal can be transmitted by the second device, that is, at this time: the second device is both a receiving device for receiving the first signal and a device for providing a carrier signal for the first device; or it can be transmitted by a third device, which is a carrier signal providing device; or it can be transmitted by a fourth device, which is a device different from the first device, the second device and the third device and has a network scheduling function, such as a gateway, a router, an access network device, a relay device, an IAB device, a Repeater device, a terminal device, an AP device, etc.

[0142] Optionally, the frequency domain related parameter of the second signal includes but is not limited to at least one of the following: (I) a center frequency point of the second signal; (II) a bandwidth of the second signal; (III) a scanning start frequency of the second signal; (IV) a scanning cutoff frequency of the second signal; (V) a scanning minimum frequency of the second signal; (VI) a scanning maximum frequency of the second signal; (VII) a slope of the scanning frequency of the second signal; (VIII) a spreading factor of the second signal; (IX) a chip rate of the second signal; (X) a symbol rate or a symbol period of the second signal; (XI) a frequency sweeping mode of the second signal, such as an up-chirp mode or a down-chirp mode; (XII) a frequency offset or frequency shift size of the second signal.

[0143] Optionally, the time domain related parameter of the second signal includes but is not limited to at least one of the following: (I) a time unit of the second signal, such as a RE, a time slot, a subframe, etc.; (II) a signal period of the second signal; (III) a signal length of the second signal; (IV) a time domain repetition number of the second signal; (V) a synchronization signal or a synchronization sequence of the second signal.

[0144] Optionally, the signal waveform and frame structure of the second signal can include at least one of the following: 1) the second signal adopts a CSS signal waveform, and the number of CSS symbols included in the second signal or the number of second signal units; 2) the second signal adopts a reference Chirp signal waveform, and the number of reference Chirp symbols included in the second signal or the number of second signal units; 3) the second signal adopts a mixed waveform of a CSS signal and a reference Chirp signal, and the proportion or number of CSS symbols and reference Chirp symbols in the second signal.

[0145] In an optional implementation, the second signal is a mixed signal of a reference Chirp signal and a CSS modulated signal, such as a CSS modulated signal with a frame structure, and the frame structure signal at least includes a CSS modulated signal or a reference Chirp signal; the mixed signal is, for example, a LoRa signal.

[0146] Optionally, the baseband signal parameters of the second signal can include at least one of the following: (I) modulation parameters of the second signal, such as but not limited to modulation mode, modulation order, modulation rate, etc.; (II) encoding parameters of the second signal, such as but not limited to channel encoding mode (such as: RS code, Polar code, convolutional code, repetition code, etc.), or line encoding mode (such as: FM0 code, Miller code, Manchester code, etc.).

[0147] In the embodiments of the present application, the first device can obtain the first information in multiple ways. The signal transmission method can further include at least one of the following: (a) the first device determines the first information, i.e., the first device itself has the capability to determine the configuration information; (b) the first device receives the first information from a second device, which is a receiving device of the first signal; i.e., at this time: the second device is both a receiving device of the first signal and a device that configures or indicates the first information; the second device can be an access network device such as a base station, a terminal device such as a UE, a relay device, a Repeater device, an IAB device, an AP device, etc.; (c) the first device receives the first information from a third device, which is a device providing a carrier signal; i.e., at this time: the third device is both a device providing a carrier signal for the first device and a device that configures or indicates the first information; the third device can be an access network device such as a base station, a terminal device such as a UE, a relay device, a Repeater device, an IAB device, an AP device, a dedicated radio frequency source device, etc.; (d) the first device receives the first information from a fourth device, which is a device with network scheduling function; the fourth device is different from the first device, the second device, and the third device, and has network scheduling function, such as a gateway, a router, an access network device, a relay device, an IAB device, a Repeater device, a terminal device, an AP device, etc.

[0148] It should be noted that in addition to the above-mentioned ways of determining or configuring / indicating the first information, the first information can also be configured / indicated by at least two of the first device to the fourth device.

[0149] Optionally, when the first information is received by the first device, the first information can be configured or indicated by at least one of the following:

[0150] Radio Resource Control (RRC) signaling; this way requires the first device to have an RRC protocol layer;

[0151] Non-Access Stratum (NAS) signaling; this way requires the first device to have an NSA protocol layer;

[0152] Medium Access Control Control Element (MAC CE); i.e., using MAC CE signaling to configure the signal parameters of the first device, which is also applicable to the first device with weak capability that does not support RRC signaling or NAS signaling;

[0153] Downlink Control Information (DCI); the DCI is physical layer signaling, that is, the first information is dynamically indicated through physical layer signaling;

[0154] Sidelink Control Information (SCI); the SCI is physical layer signaling, that is, the first information is dynamically indicated through physical layer signaling;

[0155] Layer 1 or physical layer signaling, such as a physical frame header and a preamble carrying control information, which can be placed in the same physical frame as the effective data payload, or can be placed in a physical frame alone.

[0156] Factory configuration information or default configuration information; for example, when the first device accesses the network for the first time or does not support RRC configuration information, the system configures the signal parameters related to the first signal.

[0157] It should be noted that the second information and the third information can be configured / indicated in the same way as the first information, and details are not repeated here to avoid repetition.

[0158] Please refer to FIG. 4, which is a flowchart of a signal transmission method provided by an embodiment of the present application. The method is executed by a second device, such as an access network device, a terminal device, a relay device, a repeater device, an IAB device, an AP device, etc.

[0159] As shown in FIG. 4, the method includes the following steps:

[0160] Step 41: The second device receives the first signal sent by the first device; the first signal is obtained by backscattering modulation according to the information bits to be transmitted and the second signal;

[0161] Step 42: The second device performs a subtraction operation on the two CSS symbols in the first signal unit of the first signal to obtain a third signal;

[0162] Step 43: The second device demodulates the third signal to obtain the information bits to be transmitted.

[0163] In the embodiments of the present application, the second signal is a carrier signal of the first signal. The first signal comprises at least one first signal unit, each first signal unit comprises two CSS symbols, such as two adjacent CSS symbols; the average power or reflection coefficient of the two CSS symbols is different, other parameters of the two CSS symbols are the same, and the information bits to be transmitted are modulated by the frequency of each CSS symbol in each first signal unit.

[0164] Optionally, the other parameters at least include the following: sweep frequency mode; minimum sweep frequency; maximum sweep frequency; sweep start frequency; sweep cutoff frequency; center frequency point; bandwidth; spreading factor; code rate; symbol rate; and the like.

[0165] Optionally, the waveform form of the second signal can be set based on actual needs, as long as the second signal can obtain the first signal with a repeated structure in the present application scheme.

[0166] Optionally, the second device can obtain the first signal on the specified time-frequency resource, and perform necessary radio frequency, intermediate frequency or baseband processing, etc. on the obtained first signal. Each symbol of the third signal can demodulate the transmitted information bits.

[0167] Through the scheme in the embodiments of the present application, the first signal, i.e., the backscattering CSS signal, has a repeated structure, i.e., the information bits to be transmitted are modulated by the frequency of each CSS symbol in the first signal, so that when the signal is demodulated at the second device (i.e., the receiving end), the CSS signal interference can be eliminated by means of subtraction operation, thereby effectively eliminating the CSS signal interference.

[0168] Optionally, the second signal comprises at least one second signal unit, each second signal unit comprises two CSS symbols or two reference Chirp symbols with the same parameters; the first signal is obtained according to the addition of a first part and a second part, the first part is a signal obtained by performing frequency shift and filtering on the second signal at a first frequency, and the second part is a signal obtained by performing frequency shift and filtering on the second signal at a second frequency; the frequency shift directions of the first part and the second part are opposite, and the sum of the first frequency and the second frequency is equal to the bandwidth size of the CSS symbol (or signal) or the reference Chirp symbol (or signal) in the second signal, and the first frequency and the second frequency are a frequency pair for frequency shift associated with the information bits to be transmitted. The opposite frequency shift directions can be one positive direction frequency shift and the other negative direction frequency shift, such as: if the first frequency is f 2m-1 , and the second frequency is f 2m , then the second signal can be subjected to f 2m-1a frequency shift of f 2m to the second signal; or, a frequency shift of -f 2m-1 to the second signal; or, a frequency shift of f 2m to the second signal.

[0169] Thus, on one hand, the interference of the CSS carrier signal can be eliminated by using the repetitive structure of the backscattered CSS signal (i.e., the first signal); on the other hand, by performing the frequency shift and filtering of each CSS symbol with the frequency pair associated with the information bit to be transmitted, the generated signal can satisfy the linear spread spectrum characteristic of the CSS signal, so that the transmission characteristics of the CSS signal are utilized to achieve a longer transmission coverage or transmission reliability.

[0170] In an optional embodiment, the third signal B(t) is a signal constructed based on the first signal obtained by the second device, and at least the following characteristics are satisfied:

[0171] (a) B(t) is the difference between the front and rear two CSS symbols in each signal unit of the first signal:

[0172] (I) When β2>β1, B(t) satisfies: B(nT s +t)=C(2nT s +t+T s )-C(2nT s +t)=β2C 1,n (t)-β1C 1,n (t),nT s ≤t≤(n+1)T s -1

[0173] (II) When β1>β2, B(t) satisfies: B(nT s +t)=C(2nT s +t)-C(2nT s +t-T s )=β1C 1,n (t)-β2C 1,n (t),nT s ≤t≤(n+1)T s -1

[0174] (b) The time length of one CSS symbol of the third signal is T s time units; the time unit can be a protocol-defined unit such as a symbol, a time slot, a subframe, a frame, etc., or a time unit such as a microsecond, a millisecond, a minute, etc.

[0175] (c) The parameters of the symbol in the third signal can include the following contents:

[0176] (II) bandwidth BW;

[0177] (III) spreading factor SF;

[0178] (IIV) frequency linear growth slope or

[0179] (IIIV) starting sweep frequency f of each symbol start .

[0180] (e) the basic time unit interval between each signal unit in the third signal B(t) is T g / 2≥0.

[0181] Optionally, the demodulating the third signal can include at least one of the following:

[0182] (1) the second device performs a despreading process on the third signal by using a reference despreading signal to obtain a fourth signal, and obtains the information bits to be transmitted according to the frequency points of the highest peak or the two highest peaks in the frequency domain of the fourth signal; for example, threshold judgment can be performed according to the frequency points of the highest peak or the two highest peaks in the frequency domain of the fourth signal, so as to obtain the information bits to be transmitted;

[0183] (2) the second device demodulates the third signal by using a maximum likelihood detection algorithm to obtain the information bits to be transmitted; for details of the demodulation process, please refer to the description in Embodiment III below.

[0184] In the embodiments of the present application, the second device can demodulate according to the configured or indicated information. The demodulating the third signal to obtain the information bits to be transmitted can include:

[0185] The second device demodulates the third signal according to the obtained fourth information to obtain the information bits to be transmitted; the fourth information is information related to the demodulation parameter, and the fourth information can include but is not limited to at least one of the following:

[0186] (a) the frequency value contained in the frequency pair used for frequency shift associated with the information bits to be transmitted; in this way, the information bits to be transmitted can be demodulated based on the frequency value;

[0187] (b) the size of the PRB, RBG and / or BWP of the frequency pair used for frequency shift associated with the information bits to be transmitted;

[0188] (c) a modulation mode of the first signal, such as, but not limited to, FSK-CSS modulation, binary on-off keying (OOK) modulation, amplitude shift keying (ASK) modulation, phase shift keying (PSK) modulation, frequency shift keying (FSK) modulation, quadrature amplitude modulation QAM, APSK modulation, CSS modulation, etc.;

[0189] (d) a modulation order of the first signal, such as, but not limited to, M;

[0190] (e) a modulation rate of the first signal;

[0191] (f) an encoding mode of the first signal, such as, but not limited to, a channel encoding mode (such as: RS code, Polar code, convolutional code, repetition code, etc.) or a line encoding mode (such as: FM0 code, Miller code, Manchester code, etc.);

[0192] (g) an encoding code rate of the first signal;

[0193] (h) a way of constructing the third signal, such as, but not limited to, a previous CSS symbol minus a next CSS symbol, or a next CSS symbol minus a previous CSS symbol;

[0194] (i) a signal parameter of a reference despreading signal corresponding to the first signal; wherein, when the sweep mode of the first signal is an up-chirp mode, the reference despreading signal is conjugate to a CSS signal with a lowest frequency as a scan starting frequency; or, when the sweep mode of the first signal is a down-chirp mode, the reference despreading signal is conjugate to a CSS signal with a highest frequency as a scan starting frequency; or, the reference despreading signal is conjugate to the first signal;

[0195] (j) third index information associated with the demodulation of the first signal, the third index information being used to indicate associated demodulation parameters; wherein different third index information is associated with different demodulation parameters of the first signal, and each third index information can correspond to a group of demodulation parameters of the first signal, such as, but not limited to, a) to i) described above; the corresponding relationship can be pre-configured by a network or a protocol.

[0196] Optionally, the signal parameters of the reference despreading signal include at least one of the following: (I) a sweep mode of the reference despreading signal, which is opposite to that of the first signal; that is, if the first signal adopts an up-chirp sweep mode, the reference despreading signal adopts a down-chirp sweep mode; if the first signal adopts a down-chirp sweep mode, the reference despreading signal adopts an up-chirp sweep mode; (II) a lowest sweep frequency of the reference despreading signal, which is the same as that of the first signal; (III) a highest sweep frequency of the reference despreading signal, which is the same as that of the first signal; (IV) a sweep starting frequency of the reference despreading signal, which is the lowest sweep frequency or the highest sweep frequency; for example, if the reference despreading signal is in a down-chirp sweep mode, the corresponding sweep starting frequency is the highest sweep frequency; or, if the reference despreading signal is in an up-chirp sweep mode, the corresponding sweep starting frequency is the lowest sweep frequency; (IIV) a sweep cutoff frequency of the reference despreading signal, which is the lowest sweep frequency or the highest sweep frequency; for example, if the reference despreading signal is in a down-chirp sweep mode, the corresponding sweep cutoff frequency is the lowest sweep frequency; or, if the reference despreading signal is in an up-chirp sweep mode, the corresponding sweep cutoff frequency is the highest sweep frequency; (IIIV) a center frequency of the reference despreading signal, which is the same as that of the first signal; (V) a bandwidth of the reference despreading signal, which is the same as that of the first signal; (VI) a spreading factor of the reference despreading signal, which is the same as that of the first signal; (VII) a code rate of the reference despreading signal, which is the same as that of the first signal; (VIII) a symbol rate of the reference despreading signal, which is the same as that of the first signal.

[0197] In the embodiments of the present application, the second device can receive the first signal according to the configured or indicated information. The above receiving the first signal sent by the first device can include: the second device receiving the first signal according to the obtained fifth information; the fifth information can include but is not limited to at least one of the following: a preamble or a synchronization sequence of the first signal; a reference signal of the first signal; time domain resource information of the first signal, such as including the number of repeated transmissions of the signal, the signal period, the slot configuration information, the subframe information, etc.; frequency domain resource information of the first signal, such as including the frequency, the bandwidth, etc.; spatial domain resource information of the first signal, such as including the antenna, the code word, the layer, the antenna port, etc.

[0198] In the embodiments of the present application, the second device can be configured or instructed with relevant information for transmitting a carrier signal (i.e., a second signal). The above signal transmission method can further include: the second device transmitting the second signal according to the obtained sixth information. The sixth information can include, but is not limited to, at least one of: a frequency domain related parameter of the second signal; a time domain related parameter of the second signal; a signal waveform and frame structure of the second signal; a baseband signal parameter of the second signal; second index information associated with the signal parameter of the second signal, the second index information being used to indicate the signal parameter of the associated second signal; wherein different second index information corresponds to different signal parameters of the second signal, and each second index information can correspond to a set of signal parameters of the second signal, such as a frequency domain related parameter, a time domain related parameter, and / or a signal waveform, etc. The relevant correspondence can be pre-configured by a network or a protocol. With the second index information, the first device can obtain the signal parameter of the associated second signal, so as to accurately transmit the second signal.

[0199] It should be noted that the specific content of the sixth information can refer to the description of the third information in the above embodiments, which will not be repeated here.

[0200] In the embodiments of the present application, the second device can obtain the fourth information in multiple ways. The signal transmission method can further include at least one of the following: (a) the second device determines the fourth information, i.e., the second device itself has the ability to determine the configuration information; (b) the second device receives the fourth information from the first device; (c) the second device receives the fourth information from the third device, the third device being a device providing a carrier signal; i.e., at this time: the third device is both a device providing a carrier signal for the first device and a device configuring or instructing the fourth information; (d) the second device receives the first information from the fourth device, the fourth device being a device with network scheduling function; the fourth device being a device different from the first device, the second device and the third device.

[0201] It should be noted that the fifth information and the sixth information can be configured / instructed in the same way as the fourth information, and details will not be repeated here to avoid repetition.

[0202] The present application will be described below in conjunction with specific embodiments.

[0203] Embodiment One

[0204] In this embodiment one, an example of the frame structure design of the second signal and the first signal is given.

[0205] In one possible example, as shown in FIG. 5A and FIG. 5B, the second signal is a periodic CSS signal or a reference Chirp signal, where all the symbol parameters of the CSS symbol #n and the CSS symbol #n+1 in the same symbol period k are the same, and in particular, the average power of the CSS symbol #n and the CSS symbol #n+1 are the same, and the time interval T g = 0 between any signal unit k and the signal unit k+1. Correspondingly, the time interval T g = 0 between each signal unit k and the signal unit k+1 in the first signal, and the CSS symbol #n in each signal unit is the CSS symbol #n in the corresponding second signal respectively shifted by a frequency (f 2m-1 , -f 2m ), m e {1,..., M} and filtered to generate the first part signal and the second part signal. In particular, the average power or the reflection coefficient β1 of the CSS symbol #n and the average power or the reflection coefficient β2 of the CSS symbol #n+1 in each signal unit are different, i.e., β1≠ β2. The benefit of this design is that all the symbols of the second signal are used to modulate the information bits of the first device, and thus the modulation rate is high.

[0206] In another possible example, as shown in FIG. 6A and FIG. 6B, the second signal is a periodic CSS signal or a reference Chirp signal, where all the symbol parameters of the CSS symbol #n and the CSS symbol #n+1 in the same symbol period k are the same, and in particular, the average power of the CSS symbol #n and the CSS symbol #n+1 are the same, and the time interval T g > 0 between two signal units k and the signal unit k+1. This includes: (1) the time interval T g > 0 between any two signal units k and the signal unit k+1; or, (2) the time interval T g > 0 between part of the signal units k and the signal unit k+1. Correspondingly, the time interval T g > 0 between two signal units k and the signal unit k+1 in the first signal. This includes: (1) the time interval T g > 0 between any two signal units k and the signal unit k+1; or, (2) the time interval T g > 0 between part of the signal units k and the signal unit k+1. And the CSS symbol #n in each signal unit is the CSS symbol #n in the corresponding second signal respectively shifted by a frequency (f 2m-1 , -f 2m), m e {1,..., M} frequency shifts and the addition of the first and second partial signals generated after filtering. In particular, the average power of CSS symbol #n in each signal unit or reflection coefficient β1 and the average power of CSS symbol #n+1 or reflection coefficient β2 are different, i.e. β1 ≠ β2. The advantage of this design is that the frame structure of all second signals is flexible, and other data payloads in the frame structure can be used for other services.

[0207] It is worth noting that in the present scheme, only the starting scanning frequencies of the two CSS symbols in the same signal unit of the second signal are required to be the same, but the starting scanning frequencies of the CSS symbols in signal unit m and signal unit n (m ≠ n) are not required to be the same. If the starting scanning frequencies of the CSS symbols in signal unit k and signal unit k+1 are different, the second signal itself can also carry the information bits or other services that the first device wants to send.

[0208] For example, the LoRa frame structure is a typical signal unit m and signal unit n (m ≠ n) in which the starting scanning frequencies of the CSS symbols are not necessarily the same, and the time interval between two signal units k and signal unit k+1 can be T g > 0. As shown in FIG. 7, the LoRa frame structure includes four parts: preamble, header, payload, and cyclic redundancy check (CRC). Among them, the preamble part does not need to be encoded and directly uses CSS modulation symbols, while the subsequent data is all Hamming encoded to improve error correction capability. Further, the preamble can also include three parts: variable preamble, sync word, and start frame delimiter (SFD). From a transmission point of view, although the protocol specifies a variable preamble, the length of the variable preamble is fixed in a fixed scenario or over a period of time, so from this point of view, the length of the entire preamble is also fixed, so it is very suitable for use as the second signal in the present scheme. In addition, since the payload, header, and CRC parts are encoded and the starting scanning frequency is not fixed, from the perspective of simplicity of the scheme, this part is generally not used as the second signal, and this part of the signal corresponds to the other data payload part in the present scheme, and the length is also variable. This satisfies the condition that the time interval between two signal units k and signal unit k+1 in the present scheme can be T g > 0, or more accurately, the time interval between the partial signal units k and signal unit k+1 is T g> 0. And from the preamble, the variable preamble generally adopts the reference up-chirp signal, and the signal in this part satisfies the same starting sweep frequency of the CSS symbol in the signal unit m and the signal unit n (m≠ n); while the sync word and the SFD adopt the reference down-chirp signal, and thus the last signal unit of the variable preamble and the first signal unit of the sync word satisfy the different starting sweep frequency of the CSS symbol in the signal unit m and the signal unit n (m≠ n).

[0209] Embodiment Two

[0210] In this embodiment two, a specific modulation process example is given. Without loss of generality, taking the first signal and the second signal in embodiment one as an example, the same scheme can be easily extended to other types of frame structures, which will not be described here.

[0211] Case One: The second signal is a reference CSS signal or a Chirp signal.

[0212] As shown in FIG. 8A, the second signal for the radio frequency carrier is a reference Chirp signal or a CSS signal S1(t), and at this time the second signal can satisfy the following characteristics:

[0213] (I) The center frequency is f0;

[0214] (II) The bandwidth is BW;

[0215] (III) The spread factor is SF;

[0216] (IV) The single symbol length is

[0217] (IIV) The starting sweep frequency of each symbol is fixed, which is

[0218] (IIIV) The signal S1(t) can be expressed as:

[0219] According to the method described in the scheme of the present application, in this embodiment two, the second order modulation (M=2) is considered, that is, the bits to be transmitted are “0” or “1”, and the frequency of the adjacent two CSS symbols in a signal unit of the second signal can be shifted by f1 (0≤f1≤BW) or f3 (0≤f3≤BW) respectively and filtered with the center frequency f0 and the bandwidth interval of , thereby generating the first part and Meanwhile, the frequencies of two adjacent CSS symbols in one signal unit of the second signal are shifted by -f2 (0≤f2≤BW) or -f4 (0≤f4≤BW) respectively, and filtering is performed with the center frequency f0 and the bandwidth interval of the first signal to generate the second part of the first signal and where f1+f2=BW, f3+f4=BW, f1≠f3, f2≠f4. Finally, the first part of the first signal and the second part of the first signal are added in the time domain, and different average powers or reflection coefficients are assigned to the two adjacent CSS symbols to generate the first signal.

[0220] The second embodiment is described by taking as an example. As shown in FIGS. 8B and 8C, the signal modulation process of the transmission bit is described when the second signal is a reference CSS signal or a Chirp signal.

[0221] (1) Transmission bit "0":

[0222] (a) Generating the first CSS symbol in one signal unit:

[0223] (I) Shifting the second signal with the starting scanning frequency by f1 and performing filtering with the center frequency f0 and the bandwidth interval to generate the first part of the first CSS symbol

[0224] wherein, indicates filtering of a signal with the center frequency f0 and the bandwidth interval . As shown in FIG. 8B, the red dotted line is the second signal before frequency shift, and the solid green part indicates the first part of the first signal, wherein the green solid line part indicates the useful signal within the bandwidth , and the green dotted line part indicates the filtered signal outside the bandwidth .

[0225] (II) Shifting the second signal with the starting scanning frequency by -f2 and performing filtering with the center frequency f0 and the bandwidth interval to generate the second part of the first CSS symbol

[0226] wherein, indicates filtering of a signal with the center frequency f0 and the bandwidth interval The filtering is shown in Figure 8B. The red dotted line represents the second signal before frequency shift, and the solid blue line represents the second part of the first signal. The solid blue line represents the bandwidth... The useful signal within, while the blue dashed line represents the bandwidth. External filtering signals.

[0227] (III) Add the first part and the second part of the first CSS symbol to generate the first CSS symbol in a signal unit:

[0228] (b) Generate the second CSS symbol in a signal unit:

[0229] (I) For the initial scan frequency of The second signal is frequency shifted by f1 and the center frequency is f0 with a bandwidth of [missing information]. The filtering process generates the first part of the second CSS symbol.

[0230] in, This indicates that the signal has a center frequency of f0 and a bandwidth of [value missing]. The filtering is shown in Figure 8B. The red dotted line represents the second signal before frequency shift, and the solid green line represents the first part of the first signal. The solid green line represents the bandwidth... The useful signal within, while the green dashed line represents the bandwidth. External filtering signals.

[0231] (II) For the initial scan frequency of The second signal is frequency shifted by -f2 and the center frequency is f0 with a bandwidth range of... The filtering process generates the second part of the second CSS symbol.

[0232] in, This indicates that the signal has a center frequency of f0 and a bandwidth of [value missing]. The filtering is shown in Figure 8B. The red dotted line represents the second signal before frequency shift, and the solid blue line represents the second part of the first signal. The solid blue line represents the bandwidth... The useful signal within, while the blue dashed line represents the bandwidth. External filtering signals.

[0233] (III) Add the first and second parts of the second CSS symbol to generate the second CSS symbol in a signal unit:

[0234] (c) Set different average power or reflection coefficient for the two CSS symbols respectively, and form a signal unit representing bit "0", as shown in Fig. 8B:

[0235] (2) Transmit bit "1":

[0236] (a) Generate the 1st CSS symbol in a signal unit:

[0237] (I) Shift the second signal by f3, where the initial scanning frequency is f2, and filter the signal with the center frequency f0 and the bandwidth interval , thereby generating the first part of the 1st CSS symbol wherein

[0238] represents filtering the signal with the center frequency f0 and the bandwidth interval . As shown in Fig. 8C, the red dotted line is the second signal before frequency shift, and the solid green part represents the first part of the first signal, wherein the green solid line part represents the useful signal within the bandwidth , and the green dotted line part represents the filtered signal outside the bandwidth .

[0239] (II) Shift the second signal by -f4, where the initial scanning frequency is f2, and filter the signal with the center frequency f0 and the bandwidth interval , thereby generating the second part of the 1st CSS symbol wherein

[0240] represents filtering the signal with the center frequency f0 and the bandwidth interval . As shown in Fig. 8C, the red dotted line is the second signal before frequency shift, and the solid blue part represents the second part of the first signal, wherein the blue solid line part represents the useful signal within the bandwidth , and the blue dotted line part represents the filtered signal outside the bandwidth .

[0241] (III) Add the first part and the second part of the 1st CSS symbol to generate the 1st CSS symbol in a signal unit:

[0242] (b) Generate the 2nd CSS symbol in a signal unit:

[0243] ​​(I) shift the second signal by -f3 from the starting scanning frequency and filter it with a center frequency f0 and a bandwidth interval to generate the first part of the second CSS symbol

[0244] wherein denotes filtering a signal with a center frequency f0 and a bandwidth interval . As shown in Fig. 8C, the red dotted line is the second signal before frequency shift, and the solid green part represents the first part of the first signal, wherein the solid green part represents the useful signal within the bandwidth , and the dotted green part represents the filtered signal outside the bandwidth .

[0245] (II) shift the second signal by -f4 from the starting scanning frequency and filter it with a center frequency f0 and a bandwidth interval to generate the second part of the second CSS symbol

[0246] wherein denotes filtering a signal with a center frequency f0 and a bandwidth interval . As shown in Fig. 8C, the red dotted line is the second signal before frequency shift, and the solid blue part represents the second part of the first signal, wherein the solid blue part represents the useful signal within the bandwidth , and the dotted blue part represents the filtered signal outside the bandwidth .

[0247] (III) add the first part and the second part of the second CSS symbol to generate the second CSS symbol in a signal unit:

[0248] (c) set different average powers or reflection coefficients for the two CSS symbols respectively, and compose a signal unit representing bit "1", as shown in Fig. 8C:

[0249] Case two: the second signal is a modulated CSS signal.

[0250] In the same way, it can also be extended to the second signal being a non-reference CSS signal or a modulated CSS signal. The SF of the modulated CSS signal shown in Fig. 9A is 2, wherein the starting scanning frequency of the CSS signal representing bit "01" is The starting scanning frequency of the CSS signal representing bit "10" is f0, and the starting scanning frequencies of the two adjacent CSS symbols (i.e., one signal unit) of the second signal must be the same, so the second signal shown in Fig. 9A also transmits bits with two adjacent CSS symbols that are completely the same. At this time, the second signal can satisfy the following characteristics:

[0251] (I) the center frequency is f0;

[0252] (II) the bandwidth is BW;

[0253] (III) the spreading factor is SF;

[0254] (IV) the single symbol length is

[0255] (IIV) the starting scanning frequency of each symbol is related to the modulation information of the second signal, and is n∈{0, 1,..., 2 SF -1};

[0256] (IIIV) the modulated CSS signal S2(t) can be expressed as:

[0257] According to the method of the present application, according to the bits to be transmitted, "0" or "1", the frequencies of the two adjacent CSS symbols (i.e., one signal unit) of the second signal are respectively shifted by f1 (0≤f1≤BW) or f3 (0≤f3≤BW) and filtered with the center frequency f0 and the bandwidth interval , thereby generating the first part and of the first signal. Meanwhile, the frequencies of the two adjacent CSS symbols (i.e., one signal unit) of the second signal are respectively shifted by -f2 (0≤f2≤BW) or -f4 (0≤f4≤BW) and filtered with the center frequency f0 and the bandwidth interval , thereby generating the second part and of the first signal. Wherein f1+f2=BW, f3+f4=BW, f1≠f3, f2≠f4. Finally, the first part and the second part of the first signal are added in the time domain, and different average transmission powers or reflection coefficients are assigned to the two adjacent CSS symbols, thereby generating the first signal.

[0258] The second embodiment is described by taking as an example. Taking Fig. 9A as an example, the second signal itself also modulates bit information, and the starting scanning frequency of the second signal corresponding to the transmission of bit "0" is and the starting scanning frequency of the second signal corresponding to the transmission of bit "1" isstart = f0, which indicates the modulation process of the transmission bit when the second signal is a modulated CSS signal.

[0259] The signal modulation process of the transmission bit when the second signal is a modulated CSS signal is described below with reference to FIGS. 9B and 9C.

[0260] (1) Transmission bit "0":

[0261] (a) Generating the first CSS symbol in a signal unit:

[0262] (I) Shifting the second signal by f1 with the initial scanning frequency and filtering the second signal with the center frequency f0 and the bandwidth interval to generate the first part of the first CSS symbol

[0263] wherein indicates filtering a signal with the center frequency f0 and the bandwidth interval . As shown in FIG. 9B, the red dotted line is the modulated second signal (carrying the bit "01") before frequency shifting, and the solid green part indicates the first part of the first signal, wherein the green solid line part indicates the useful signal within the bandwidth , and the green dotted line part indicates the filtered signal outside the bandwidth .

[0264] (II) Shifting the second signal by -f2 with the initial scanning frequency and filtering the second signal with the center frequency f0 and the bandwidth interval to generate the second part of the first CSS symbol

[0265] wherein indicates filtering a signal with the center frequency f0 and the bandwidth interval . As shown in FIG. 9B, the red dotted line is the modulated second signal (carrying the bit "01") before frequency shifting, and the solid blue part indicates the second part of the first signal, wherein the blue solid line part indicates the useful signal within the bandwidth , and the blue dotted line part indicates the filtered signal outside the bandwidth .

[0266] (III) Adding the first part and the second part of the first CSS symbol to generate the first CSS symbol in a signal unit:

[0267] (b) generating the second CSS symbol in a signal unit:

[0268] (I) frequency shifting the second signal by f1with a starting scanning frequency of and filtering with a center frequency of f0and a bandwidth interval of to generate the first part of the second CSS symbol

[0269] wherein represents filtering of the signal with a center frequency of f0and a bandwidth interval of As shown in FIG. 9B, the red dotted line is the modulated second signal (carrying bit "01") before frequency shifting, and the solid green part represents the first part of the first signal, wherein the green solid line part represents the useful signal within the bandwidth , and the green dotted line part represents the filtered signal outside the bandwidth .

[0270] (II) frequency shifting the second signal by -f2with a starting scanning frequency of and filtering with a center frequency of f0and a bandwidth interval of to generate the second part of the second CSS symbol

[0271] wherein represents filtering of the signal with a center frequency of f0and a bandwidth interval of As shown in FIG. 9B, the red dotted line is the modulated second signal (carrying bit "01") before frequency shifting, and the solid blue part represents the second part of the first signal, wherein the blue solid line part represents the useful signal within the bandwidth , and the blue dotted line part represents the filtered signal outside the bandwidth .

[0272] (III) adding the first part and the second part of the second CSS symbol to generate the second CSS symbol in a signal unit:

[0273] (c) setting different average powers or reflection coefficients for the two CSS symbols respectively, and composing a signal unit representing bit "0", as shown in FIG. 9B:

[0274] (2) transmitting bit "1":

[0275] (a) generating a first CSS symbol in a signal unit:

[0276] (I) frequency shifting the second signal by f3 from a starting scanning frequency f0 and filtering the signal with a center frequency f0 and a bandwidth interval to generate a first part of the first CSS symbol

[0277] wherein represents filtering a signal with a center frequency f0 and a bandwidth interval As shown in FIG. 9C, the red dotted line is the modulated second signal (carrying bits "10") before frequency shifting, and the solid green part represents the first part of the first signal, wherein the green solid line part represents the useful signal within the bandwidth , and the green dotted line part represents the filtered signal outside the bandwidth

[0278] (II) frequency shifting the second signal by -f4 from the starting scanning frequency f0 and filtering the signal with a center frequency f0 and a bandwidth interval to generate a second part of the first CSS symbol

[0279] wherein represents filtering a signal with a center frequency f0 and a bandwidth interval As shown in FIG. 9C, the red dotted line is the modulated second signal (carrying bits "10") before frequency shifting, and the solid blue part represents the second part of the first signal, wherein the blue solid line part represents the useful signal within the bandwidth , and the blue dotted line part represents the filtered signal outside the bandwidth

[0280] (III) adding the first part and the second part of the first CSS symbol to generate the first CSS symbol in a signal unit:

[0281] (b) generating a second CSS symbol in a signal unit:

[0282] (I) frequency shifting the second signal by f3 from a starting scanning frequency f0 and filtering the signal with a center frequency f0 and a bandwidth interval to generate a first part of the second CSS symbol

[0283] wherein​​ represents filtering of the signal with a center frequency f0and a bandwidth interval As shown in Fig. 9C, the red dotted line represents the modulated second signal (carrying bit "10") before frequency shift, and the solid blue part represents the second part of the first signal, where the blue solid part represents the useful signal within the bandwidth , and the blue dotted part represents the filtered signal outside the bandwidth

[0284] (II) frequency shift the second signal with a starting scanning frequency f0by -f4, and filter the signal with a center frequency f0and a bandwidth interval , thereby generating the second part of the 2nd CSS symbol

[0285] wherein, represents filtering of the signal with a center frequency f0and a bandwidth interval As shown in Fig. 9C, the red dotted line represents the modulated second signal (carrying bit "10") before frequency shift, and the solid blue part represents the second part of the first signal, where the blue solid part represents the useful signal within the bandwidth , and the blue dotted part represents the filtered signal outside the bandwidth

[0286] (III) add the first part and the second part of the 2nd CSS symbol to generate the 2nd CSS symbol in a signal unit:

[0287] (c) set different average powers or reflection coefficients for the two CSS symbols respectively, and compose a signal unit representing bit "1", as shown in Fig. 9C:

[0288] Embodiment Three

[0289] In this embodiment three, the corresponding demodulation process is given. Without loss of generality, this embodiment three only takes the frame structure as centralized (the scheme 1 in embodiment one) and takes the reference CSS symbol or Chirp signal as the second signal (the scheme 1 in embodiment two) as an example for illustration. Similar demodulation schemes can be extended to the demodulation in other schemes. The following briefly describes the demodulation process:

[0290] (1) obtain the first signal;

[0291] (a) optionally, the second device starts to acquire the first signal after necessary time-frequency synchronization; ​​

[0292] (b) Optionally, the second device performs radio frequency or intermediate frequency processing such as down-conversion and intermediate frequency filtering on the obtained first signal;

[0293] (c) Optionally, the second device performs baseband signal processing such as channel estimation, channel equalization, and channel decoding on the obtained first signal.

[0294] (2) Obtaining the third signal and removing interference from the second signal: Each pair of CSS symbols in the obtained first signal is treated as a signal unit. The average power or reflection coefficient (e.g., β1 and β2) of the preceding and following CSS symbols is determined based on indication or configuration information, or the second device itself determines the average power of the preceding and following CSS symbols. This determines the third signal B(t) to be either the preceding CSS symbol minus the following CSS symbol, or the following CSS symbol minus the preceding CSS symbol, within the signal unit. That is, one symbol in B(t) is the difference between the preceding and following CSS symbols in each signal unit of the first signal.

[0295] (a) When β2>β1, B(t) can be expressed as: B(nT) = ... s +t)=C(2nT s +t+T s )-C(2nT s +t)=β2C 1,n (t)-β1C 1,n (t),nT s ≤t≤(n+1)T s -1

[0296] (b) When β1>β2, B(t) can be expressed as: B(nT) = ... s +t)=C(2nT s +t)-C(2nT s +tT s )=β1C 1,n (t)-β2C 1,n (t),nT s ≤t≤(n+1)T s -1

[0297] (c) Further, since the second signal (carrier signal) received by the second device is also subtracted according to the steps of (a) or (b), and since the average power of the two CSS symbols in the same signal unit in the second signal or the reflection coefficient is the same, the subtraction of the two CSS symbols in each signal unit of the second signal is 0, thereby effectively eliminating / eliminating the influence of the second signal on the demodulation of the third signal.

[0298] (3) According to the obtained third signal, demodulation is performed by at least one of the following ways:

[0299] (a) The second device first performs despread processing on the third signal using the reference despread signal, and then uses the FFT algorithm to find the frequency point of the highest peak or the two highest peaks in the frequency domain, and makes a decision according to the preset threshold.

[0300] In a possible demodulation scheme, the second device first performs despread processing on the obtained third signal using the reference despread signal through indication or configuration information, and then finds the frequency point of the highest peak or the two highest peaks in the frequency domain through FFT processing, and completes the demodulation of the information bits according to the decision threshold corresponding to the bit "0" and the bit "1". Since the starting frequency of the third signal representing the bit "0" and the bit "1" is different, the position of the first peak of the third signal and / or the difference between the second peak and the first peak can be used to determine whether the transmitted bit is "0" or "1". As shown in FIG. 10, taking the parameters in the first embodiment as an example, since the starting scanning frequency of the transmitted bit "0" is The starting scanning frequency of the transmitted bit "1" is Therefore, the receiving end can determine whether the transmitted bit is "0" or "1" by the position of the highest peak of the FFT, and the demodulation rule is as follows:

[0301] This demodulation scheme is relatively simple to implement.

[0302] (b) The second device uses the maximum likelihood detection algorithm to make a decision and demodulation.

[0303] In a possible demodulation scheme, since the CSS symbols with the same SF value but different starting scanning frequencies and the CSS symbols with different SF values have quasi-orthogonal characteristics, the receiving end can use the maximum likelihood detection algorithm for demodulation. Specifically, the receiving end first saves the third signal waveform corresponding to different information bits, and when demodulating, the third signal corresponding to different information bits is correlated with the obtained third signal, and the information bit with the maximum correlation value is the information bit corresponding to the demodulation. This demodulation scheme belongs to the optimal decision method in demodulation, and therefore the BER or SER performance is better than that of the hard decision.

[0304] (4) The demodulation method according to any one of (1) to (3), wherein all the symbols of the third signal are sequentially demodulated, and the transmission bits of the first device are obtained.

[0305] Note that the above demodulation scheme only gives two possible demodulation methods, but is not limited thereto, and will not be described again.

[0306] It is worth noting that the demodulation scheme corresponding to the modulation scheme in the second embodiment needs to consider the influence of the modulated information of the second signal itself. Since the second signal is a modulated CSS signal, when demodulating the information bits transmitted by the first device, the information bits of the second signal itself transmitted by the second device need to be demodulated first, and the influence of the second signal on the first signal is removed from the receiving end, and then the original information bits are demodulated according to the modulation rule of the information bits. A feasible scheme is that since the second device receives the second signal from the first device with a signal strength greater than that of the first signal, the second device can first demodulate the information bits of the second signal. Then, when demodulating the first signal, the influence of the modulated information bits of the second signal is removed, and the demodulation is performed through the same scheme as described above. In another feasible scheme, the second device simultaneously demodulates the information bits of the first device and the information bits carried by the second signal through joint demodulation decision.

[0307] Embodiment Four

[0308] In the above-mentioned embodiments one, two and three, the second-order modulation is taken as an example, that is, each CSS symbol of the first signal only transmits bit "0" or bit "1". However, the present scheme can also be extended to high-order modulation, so as to further improve the modulation rate or spectral efficiency of the first signal transmitted by the first device. Without loss of generality, the second signal is taken as an example of a reference CSS signal or a Chirp signal, and the same scheme can be extended to the case where the second signal is a modulated CSS signal.

[0309] When M (0≤M≤2 SF ) order modulation is realized in the first signal, each two CSS symbols (i.e., one signal unit) can carry log2 M bits. According to the log2 M bits to be transmitted, the frequencies of the adjacent two CSS symbols in each signal unit of the second signal are all shifted by f 2m-1 (0≤f 2m-1 ≤BW, m∈{1,2,…,M}) and filtered with a center frequency f0 and a bandwidth interval , thereby generating the first part and Meanwhile, the adjacent two CSS symbols (i.e. one signal unit) in each signal unit of the second signal are frequency-shifted by -f 2m (0≤f 2m ≤BW,m∈{1,2,…,M}) and filtered with the filter whose center frequency is f0and bandwidth interval is to generate the second part of the first signal and where f 2m-1 +f 2m =BW,f 2m-1 ≠f 2n-1 (n≠m),f 2m ≠f 2n (n≠m). Finally, the first part and the second part in each CSS symbol of the first signal are added in time domain, and the adjacent two CSS symbols are assigned with different average power or reflection coefficient, thereby generating the first signal.

[0310] For example, when M=8, the values of (f 2m-1 ,f 2m ) can be shown in Table 1 as follows:

[0311] Table 1

[0312] Taking M=8 as an example, and the bit-symbol adopts Gray mapping, Table 1 gives a design example of (f 2m-1 ,f 2m ). At this time, the first device implements 8-order modulation in the first signal, and each signal unit or every two CSS symbols can carry 3 bits. According to the 3 bits to be transmitted, the frequency shift f 2m-1 (0≤f 2m-1 ≤BW,m∈{1,2, … ,8}) of the adjacent two CSS symbols (i.e. one signal unit) of the second signal is performed, and the filter whose center frequency is f0and bandwidth interval is to generate the first part of the first signal and Meanwhile, the adjacent two CSS symbols (i.e. one signal unit) in each signal unit of the second signal are frequency-shifted by -f 2m (0≤f 2m ≤BW,m∈{1,2, … ,8}) and filtered with the filter whose center frequency is f0and bandwidth interval is to generate the second part of the first signal and where f 2m-1 +f 2m =BW,f 2m-1 ≠f2n-1 (n≠m),f 2m ≠f 2n (n≠m). Finally, the first part and the second part of the first signal are added in time domain, and different average powers or reflection coefficients are assigned to the adjacent two CSS symbols, so as to generate the first signal.

[0313] The specific modulation mode in this embodiment four can be extended based on the embodiments one and two. Since the corresponding modulation modes are similar, details are not described herein. The corresponding demodulation process can also be extended based on the demodulation method of high-order modulation described in the embodiment three. Details of the specific demodulation process are not described herein.

[0314] The signal transmission method provided in the embodiments of the present application can be executed by a signal transmission device. In the embodiments of the present application, the signal transmission method is executed by the signal transmission device as an example to illustrate the signal transmission device provided in the embodiments of the present application.

[0315] Please refer to FIG. 11, which is a structural schematic diagram of a signal transmission device provided in the embodiments of the present application. The device is applied to a first device, such as a backscattering device and the like. As shown in FIG. 11, the signal transmission device 110 includes: a modulation module 111, configured to perform backscattering modulation on a second signal according to information bits to be transmitted and the second signal, to obtain a first signal; wherein the second signal is a carrier signal of the first signal; the first signal includes at least one first signal unit, each first signal unit includes two CSS symbols, the average power or reflection coefficient of the two CSS symbols is different, other parameters of the two CSS symbols are the same, and the information bits to be transmitted are modulated by the frequency of each CSS symbol in each first signal unit; and a sending module 112, configured to send the first signal.

[0316] Optionally, the second signal includes at least one second signal unit, each second signal unit includes two CSS symbols or two reference Chirp symbols with the same parameters; the first signal is obtained according to the addition of a first part and a second part, the first part is a signal obtained by performing frequency shift and filtering on the second signal at a first frequency, and the second part is a signal obtained by performing frequency shift and filtering on the second signal at a second frequency; the frequency shift directions of the first part and the second part are opposite, and the sum of the first frequency and the second frequency is equal to the bandwidth size of the CSS symbol or the reference Chirp symbol in the second signal, the first frequency and the second frequency are a frequency pair used for frequency shift associated with the information bits to be transmitted.

[0317] Optionally, the filtering is a filter with a center frequency f0 and a bandwidth interval filtering of the second signal, the f0 being a center frequency of a CSS signal or a reference Chirp signal in the second signal, the BW being a bandwidth of a CSS symbol or a reference Chirp symbol in the second signal.

[0318] Optionally, the second signal satisfies at least one of the following:

[0319] average power of two CSS symbols in each of the second signal units is the same, or average power of two reference Chirp symbols in each of the second signal units is the same;

[0320] a time interval between two adjacent second signal units in the second signal is greater than or equal to 0.

[0321] Optionally, the modulation module 111 is specifically configured to: according to obtained first information, perform backscatter modulation on the information bits to be transmitted and the second signal to obtain the first signal; wherein the first information includes at least one of the following: a frequency value contained in a frequency pair for frequency shift associated with the information bits to be transmitted; a size of a physical resource block (PRB), a resource block group (RBG) and / or a bandwidth part (BWP) of the frequency pair for frequency shift associated with the information bits to be transmitted; a modulation mode of the first signal; a modulation order of the first signal; a modulation rate or a backscatter link frequency (BLF) of the first signal; an encoding mode of the first signal; a coding rate of the first signal; average power or a reflection coefficient of two CSS symbols in a first signal unit of the first signal; first index information associated with modulation and coding of the first signal, the first index information being used to indicate associated modulation and coding parameters.

[0322] Optionally, the other parameters at least include the following: a sweeping mode; a lowest sweeping frequency; a highest sweeping frequency; a sweeping start frequency; a sweeping cutoff frequency; a center frequency point; a bandwidth; a spreading factor; a code rate; a symbol rate.

[0323] Optionally, the sending module 112 is specifically configured to: according to obtained second information, send the first signal; wherein the second information includes at least one of the following: a sending power of the first signal; a preamble or a synchronization sequence of the first signal; a reference signal of the first signal; time domain resource information of the first signal; frequency domain resource information of the first signal; space domain resource information of the first signal.

[0324] Optionally, the signal transmission device 110 further includes a first receiving module configured to receive the second signal according to obtained third information, wherein the third information includes at least one of the following: a frequency domain related parameter of the second signal; a time domain related parameter of the second signal; a signal waveform and frame structure of the second signal; a baseband signal parameter of the second signal; and second index information associated with the signal parameter of the second signal, the second index information being used to indicate the associated carrier signal parameter.

[0325] Optionally, the frequency domain related parameter of the second signal includes at least one of the following: a center frequency point of the second signal; a bandwidth of the second signal; a scanning start frequency of the second signal; a scanning cutoff frequency of the second signal; a scanning minimum frequency of the second signal; a scanning maximum frequency of the second signal; a slope of the scanning frequency of the second signal; a spreading factor of the second signal; a chip rate of the second signal; a symbol rate or symbol period of the second signal; a frequency sweeping mode of the second signal; and a frequency offset or frequency shift size of the second signal.

[0326] Optionally, the time domain related parameter of the second signal includes at least one of the following: a time unit of the second signal; a signal period of the second signal; a signal length of the second signal; a time domain repetition number of the second signal; and a synchronization signal or synchronization sequence of the second signal.

[0327] Optionally, the signal waveform and frame structure of the second signal includes at least one of the following:

[0328] The second signal adopts a CSS signal waveform, and the number of CSS symbols or the number of second signal units included in the second signal;

[0329] The second signal adopts a reference Chirp signal waveform, and the number of reference Chirp symbols or the number of second signal units included in the second signal;

[0330] The second signal adopts a mixed waveform of a CSS signal and a reference Chirp signal, and the proportion or number of CSS symbols and reference Chirp symbols in the second signal.

[0331] The signal transmission device 110 provided by the embodiments of the present application can implement each process implemented by the method embodiment shown in FIG. 3 and achieve the same technical effects. To avoid repetition, details are not described herein.

[0332] Please refer to FIG. 12, which is a structural schematic diagram of a signal transmission device provided in an embodiment of the present application. The device is applied to a second device, such as an access network device (e.g., a base station), a terminal device (e.g., a UE), a relay device, a Repeater device, an IAB device, an AP device, etc. As shown in FIG. 12, the signal transmission device 120 includes: a second receiving module 121 configured to receive a first signal sent by a first device; wherein the first signal is obtained by backscattering modulation according to information bits to be transmitted and a second signal, and the second signal is a carrier signal of the first signal; the first signal includes at least one first signal unit, each first signal unit includes two CSS symbols, the average power or the reflection coefficient of the two CSS symbols is different, the other parameters of the two CSS symbols are the same, and the information bits to be transmitted are modulated by the frequency of each CSS symbol in each first signal unit; a calculation module 122 configured to perform a subtraction operation on the two CSS symbols in the first signal unit of the first signal to obtain a third signal; and a demodulation module 123 configured to demodulate the third signal to obtain the information bits to be transmitted.

[0333] Optionally, the second signal includes at least one second signal unit, each second signal unit includes two CSS symbols or two Chirp symbols with the same parameters; the first signal is obtained by adding a first part and a second part, the first part is a signal obtained by performing frequency shift and filtering on the second signal at a first frequency, and the second part is a signal obtained by performing frequency shift and filtering on the second signal at a second frequency; the frequency shift directions of the first part and the second part are opposite, and the sum of the first frequency and the second frequency is equal to the bandwidth size of the CSS symbol or the reference Chirp symbol in the second signal, and the first frequency and the second frequency are a frequency pair used for frequency shift associated with the information bits to be transmitted.

[0334] Optionally, the demodulation module 123 is specifically configured to perform at least one of the following:

[0335] performing de-spreading processing on the third signal by using a reference de-spreading signal to obtain a fourth signal, and obtaining the information bits to be transmitted according to the frequency points of the highest peak or the two highest peaks in the frequency domain of the fourth signal;

[0336] performing demodulation on the third signal by using a maximum likelihood detection algorithm to obtain the information bits to be transmitted.

[0337] Optionally, the demodulating module 123 is specifically configured to: demodulate the third signal according to obtained fourth information to obtain the information bits to be transmitted; wherein the fourth information comprises at least one of the following:

[0338] a frequency value contained in a frequency pair for frequency shift associated with the information bits to be transmitted;

[0339] a size of a PRB, RBG and / or BWP of the frequency pair for frequency shift associated with the information bits to be transmitted;

[0340] a modulation mode of the first signal;

[0341] a modulation order of the first signal;

[0342] a modulation rate of the first signal;

[0343] an encoding mode of the first signal;

[0344] an encoding code rate of the first signal;

[0345] a manner of constructing the third signal;

[0346] a signal parameter of a reference despreading signal corresponding to the first signal; wherein when a sweep frequency mode of the first signal is an up-chirp mode, the reference despreading signal is conjugate to a CSS signal with a lowest sweep starting frequency; or when the sweep frequency mode of the first signal is a down-chirp mode, the reference despreading signal is conjugate to a CSS signal with a highest sweep starting frequency; or the reference despreading signal is conjugate to the first signal;

[0347] third index information associated with demodulation of the first signal, the third index information being used to indicate an associated demodulation parameter.

[0348] Optionally, the signal parameter of the reference despreading signal comprises at least one of the following: a sweep frequency mode of the reference despreading signal; a lowest sweep frequency of the reference despreading signal; a highest sweep frequency of the reference despreading signal; a sweep starting frequency of the reference despreading signal; a sweep cutoff frequency of the reference despreading signal; a center frequency point of the reference despreading signal; a bandwidth of the reference despreading signal; a spreading factor of the reference despreading signal; a code rate of the reference despreading signal; and a symbol rate of the reference despreading signal.

[0349] Optionally, the second receiving module 121 is specifically configured to receive the first signal according to obtained fifth information; the fifth information includes at least one of the following: a preamble or a synchronization sequence of the first signal; a reference signal of the first signal; time domain resource information of the first signal; frequency domain resource information of the first signal; and spatial domain resource information of the first signal.

[0350] The signal transmission apparatus 120 provided by the embodiments of the present application can implement each process of the method embodiments shown in FIG. 3 and achieve the same technical effects. To avoid repetition, details are not described herein.

[0351] As shown in FIG. 13, the embodiments of the present application further provide a communication device 130, which includes a processor 131 and a memory 132, and the memory 132 stores programs or instructions executable on the processor 131. For example, when the communication device 130 is a first device, the programs or instructions are executed by the processor 131 to implement each step of the signal transmission method embodiments shown in FIG. 3 and achieve the same technical effects. When the communication device 130 is a second device, the programs or instructions are executed by the processor 131 to implement each step of the signal transmission method embodiments shown in FIG. 4 and achieve the same technical effects. To avoid repetition, details are not described herein.

[0352] The embodiments of the present application further provide a readable storage medium, which stores programs or instructions executable by a processor to implement each process of the above signal transmission method embodiments and achieve the same technical effects. To avoid repetition, details are not described herein.

[0353] The processor is the processor in the terminal in the above embodiments. The readable storage medium includes a computer readable storage medium, such as a computer readable only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc. In some examples, the readable storage medium can be a non-transitory readable storage medium.

[0354] The embodiments of the present application further provide a chip, which includes a processor and a communication interface, the communication interface is coupled with the processor, and the processor is configured to run programs or instructions to implement each process of the above signal transmission method embodiments and achieve the same technical effects. To avoid repetition, details are not described herein.

[0355] It should be understood that the chip mentioned in the embodiments of the present application can also be referred to as a system chip, a system on chip, a chip system or a system on chip, etc.

[0356] The embodiment of the present application further provides a computer program / program product stored in a storage medium, which is executed by at least one processor to implement the processes of the above signal transmission method embodiment, and can achieve the same technical effects. To avoid repetition, details are not described herein.

[0357] The embodiment of the present application further provides a communication system, which comprises a first device and a second device. The first device can be used to execute the steps of the signal transmission method as shown in Fig. 3, and the second device can be used to execute the steps of the signal transmission method as shown in Fig. 4.

[0358] It should be noted that, in this document, the terms "comprising", "including", or any other variant thereof are intended to cover non-exclusive inclusions, so that processes, methods, articles, or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed, or further include elements inherent to such processes, methods, articles, or devices. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or device that includes the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, but can also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method can be performed in an order different from that described, and various steps can also be added, omitted or combined. In addition, the features described with reference to certain examples can be combined in other examples.

[0359] From the above description of the embodiments, those skilled in the art can clearly understand that the above embodiment method can be realized by means of computer software product and general hardware platform, of course, it can also be realized by hardware. The computer software product is stored in a storage medium (such as ROM, RAM, magnetic disk, optical disk, etc.), which includes a plurality of instructions for making the terminal or network side device execute the method described in each embodiment of the present application.

[0360] The embodiments of the present application are described above in combination with the drawings, but the present application is not limited to the above specific embodiments, which are only illustrative and not restrictive. Those skilled in the art can make many forms of embodiments under the inspiration of the present application without departing from the scope of the present application and the protection scope of the claims.

Claims

A signal transmission method, comprising: The first device performs backscatter modulation based on the information bits to be transmitted and the second signal to obtain a first signal; wherein, the second signal is the carrier signal of the first signal; the first signal includes at least one first signal unit, each first signal unit includes two chirped spread spectrum (CSS) symbols, the average power or reflection coefficient of the two CSS symbols is different, and the other parameters of the two CSS symbols are the same except for the average power and reflection coefficient, and the information bits to be transmitted are modulated by the frequency of each CSS symbol in each first signal unit; The first device sends the first signal. According to the method of claim 1, wherein, The second signal includes at least one second signal unit, each second signal unit including two CSS symbols or two reference chirp symbols with the same parameters; The first signal is obtained by adding a first part and a second part. The first part is the signal obtained by frequency shifting and filtering the second signal at a first frequency, and the second part is the signal obtained by frequency shifting and filtering the second signal at a second frequency. The frequency shift directions of the first part and the second part are opposite, and the sum of the first frequency and the second frequency is equal to the bandwidth of the CSS symbol or reference Chirp symbol in the second signal. The first frequency and the second frequency are frequency pairs associated with the information bits to be transmitted for frequency shifting. The method according to claim 2, wherein, The filtering is performed with a center frequency of f0 and a bandwidth range of... The filtering is performed where f0 is the center frequency of the CSS signal or the reference Chirp signal in the second signal, and BW is the bandwidth of the CSS symbol or the reference Chirp symbol in the second signal. The method according to claim 2 or 3, wherein, The second signal satisfies at least one of the following: The average power of the two CSS symbols in each of the second signal units is the same, or the average power of the two reference Chirp symbols in each of the second signal units is the same; The time interval between two adjacent second signal units in the second signal is greater than or equal to 0. The method according to any one of claims 2 to 4, wherein, The first device performs backscatter modulation based on the information bits to be transmitted and the second signal to obtain a first signal, including: The first device performs backscatter modulation on the information bits to be transmitted and the second signal based on the obtained first information to obtain the first signal; The first information includes at least one of the following: The frequency values ​​contained in the frequency pair used for frequency shifting associated with the information bits to be transmitted; The size of the physical resource block (PRB), resource block group (RBG), and / or bandwidth portion (BWP) of the frequency pair associated with the information bits to be transmitted for frequency shifting. The modulation method of the first signal; The modulation order of the first signal; The modulation rate or backscatter link frequency (BLF) of the first signal; The encoding method of the first signal; The coding rate of the first signal; The average power or reflection coefficient of the two CSS symbols in the first signal unit of the first signal; A first index information associated with the modulation and coding of the first signal, the first index information being used to indicate the associated modulation and coding parameters. The method according to any one of claims 1 to 5, wherein, The other parameters include at least the following: Frequency sweeping method; minimum sweep frequency; maximum sweep frequency; sweep start frequency; sweep stop frequency; center frequency; bandwidth; spreading factor; code rate; symbol rate. The method according to any one of claims 1 to 6, wherein, The first device sends the first signal, including: The first device sends the first signal based on the obtained second information; The second information includes at least one of the following: The transmission power of the first signal; The preamble or synchronization sequence of the first signal; The reference signal of the first signal; The time-domain resource information of the first signal; Frequency domain resource information of the first signal; The spatial resource information of the first signal. The method according to any one of claims 1 to 7, wherein, The method further includes: The first device receives the second signal based on the obtained third information; The third information includes at least one of the following: Frequency domain correlation parameters of the second signal; The time-domain correlation parameters of the second signal; The signal waveform and frame structure of the second signal; The baseband signal parameters of the second signal; Second index information associated with the signal parameters of the second signal, the second index information being used to indicate the associated carrier signal parameters. The method according to claim 8, wherein, The frequency domain correlation parameters of the second signal include at least one of the following: The center frequency of the second signal; The bandwidth of the second signal; The scan start frequency of the second signal; The scanning cutoff frequency of the second signal; The lowest scanning frequency of the second signal; The highest scanning frequency of the second signal; The slope of the scanning frequency of the second signal; The spreading factor of the second signal; The chip rate of the second signal; The symbol rate or symbol period of the second signal; The frequency sweep method of the second signal; The frequency offset or shift magnitude of the second signal. The method according to claim 8, wherein, The time-domain correlation parameters of the second signal include at least one of the following: The time unit of the second signal; The signal period of the second signal; The signal length of the second signal; The number of time-domain repetitions of the second signal; The second signal is a synchronization signal or synchronization sequence. The method according to claim 8, wherein, The signal waveform and frame structure of the second signal include at least one of the following: The second signal adopts a CSS signal waveform, and the number of CSS symbols or the number of second signal units included in the second signal; The second signal adopts a reference Chirp signal waveform, and the number of reference Chirp symbols or the number of second signal units included in the second signal; The second signal is a mixed waveform of the CSS signal and the reference Chirp signal, and the proportion or number of CSS symbols and reference Chirp symbols in the second signal. A signal transmission method, comprising: The second device receives a first signal sent by the first device; wherein the first signal is obtained by backscattering modulation based on the information bits to be transmitted and a second signal, and the second signal is the carrier signal of the first signal; the first signal includes at least one first signal unit, each first signal unit includes two CSS symbols, the average power or reflection coefficient of the two CSS symbols is different, and the other parameters of the two CSS symbols are the same except for the average power and reflection coefficient, and the information bits to be transmitted are modulated by the frequency of each CSS symbol in each first signal unit; The second device performs a subtraction operation on the two CSS symbols in the first signal unit of the first signal to obtain the third signal; The second device demodulates the third signal to obtain the information bits to be transmitted. The method according to claim 12, wherein, The second signal includes at least one second signal unit, each second signal unit including two CSS symbols or two Chirp symbols with the same parameters; The first signal is obtained by adding a first part and a second part. The first part is the signal obtained by frequency shifting and filtering the second signal at a first frequency, and the second part is the signal obtained by frequency shifting and filtering the second signal at a second frequency. The frequency shift directions of the first part and the second part are opposite, and the sum of the first frequency and the second frequency is equal to the bandwidth of the CSS symbol or reference Chirp symbol in the second signal. The first frequency and the second frequency are frequency pairs associated with the information bits to be transmitted for frequency shifting. The method according to claim 12 or 13, wherein, The second device demodulates the third signal to obtain the information bits to be transmitted, including at least one of the following: The second device uses a reference despreading signal to despread the third signal to obtain a fourth signal, and obtains the information bits to be transmitted based on the frequency points of the highest frequency peak or the two highest frequency peaks in the fourth signal. The second device uses the maximum likelihood detection algorithm to demodulate the third signal to obtain the information bits to be transmitted. The method according to any one of claims 12 to 14, wherein, The second device demodulates the third signal to obtain the information bits to be transmitted, including: The second device demodulates the third signal based on the obtained fourth information to obtain the information bits to be transmitted; The fourth piece of information includes at least one of the following: The frequency values ​​contained in the frequency pair used for frequency shifting associated with the information bits to be transmitted; The size of the PRB, RBG, and / or BWP of the frequency pair used for frequency shifting associated with the information bits to be transmitted; The modulation method of the first signal; The modulation order of the first signal; The modulation rate of the first signal; The encoding method of the first signal; The coding rate of the first signal; The method of constructing the third signal; The signal parameters of the reference despread signal corresponding to the first signal; wherein, when the frequency sweep mode of the first signal is up-chirp mode, the reference despread signal is conjugate with the CSS signal whose scan start frequency is the lowest frequency; or, when the frequency sweep mode of the first signal is down-chirp mode, the reference despread signal is conjugate with the CSS signal whose scan start frequency is the highest frequency; or, the reference despread signal is conjugate with the first signal; A third index information associated with the demodulation of the first signal, the third index information being used to indicate the associated demodulation parameters. The method according to claim 15, wherein, The signal parameters of the reference despread signal include at least one of the following: The frequency sweep method of the reference despread signal; The lowest sweep frequency of the reference despread signal; The highest sweep frequency of the reference despread signal; The sweep start frequency of the reference despread signal; The sweep cutoff frequency of the reference despread signal; The center frequency point of the reference despread signal; The bandwidth of the reference despread signal; The spreading factor of the reference despread signal; The code rate of the reference despread signal; The symbol rate of the reference despread signal. The method according to any one of claims 12 to 16, wherein, The second device receives a first signal sent by the first device, including: The second device receives the first signal based on the obtained fifth information; The fifth piece of information includes at least one of the following: The preamble or synchronization sequence of the first signal; The reference signal of the first signal; The time-domain resource information of the first signal; Frequency domain resource information of the first signal; The spatial resource information of the first signal. A signal transmission device, comprising: A modulation module is used by a first device to perform backscatter modulation based on information bits to be transmitted and a second signal to obtain a first signal; wherein the second signal is the carrier signal of the first signal; the first signal includes at least one first signal unit, each first signal unit includes two CSS symbols, the average power or reflection coefficient of the two CSS symbols is different, and the other parameters of the two CSS symbols are the same except for the average power and reflection coefficient; the information bits to be transmitted are modulated by the frequency of each CSS symbol in each first signal unit; A transmitting module is used to transmit the first signal. The apparatus according to claim 18, wherein, The second signal includes at least one second signal unit, each second signal unit including two CSS symbols or two Chirp symbols with the same parameters; The first signal is obtained by adding a first part and a second part. The first part is the signal obtained by frequency shifting and filtering the second signal at a first frequency, and the second part is the signal obtained by frequency shifting and filtering the second signal at a second frequency. The frequency shift directions of the first part and the second part are opposite, and the sum of the first frequency and the second frequency is equal to the bandwidth of the CSS symbol or reference Chirp symbol in the second signal. The first frequency and the second frequency are frequency pairs associated with the information bits to be transmitted for frequency shifting. The apparatus according to claim 18 or 19, wherein, The modulation module is specifically used to: perform backscatter modulation on the information bits to be transmitted and the second signal according to the obtained first information to obtain the first signal; The first information includes at least one of the following: The frequency values ​​contained in the frequency pair used for frequency shifting associated with the information bits to be transmitted; The size of the PRB, RBG, and / or BWP of the frequency pair used for frequency shifting associated with the information bits to be transmitted; The modulation method of the first signal; The modulation order of the first signal; The modulation rate or backscatter link frequency (BLF) of the first signal; The encoding method of the first signal; The coding rate of the first signal; The average power or reflection coefficient of the two CSS symbols in the first signal unit of the first signal; A first index information associated with the modulation and coding of the first signal, the first index information being used to indicate the associated modulation and coding parameters. A signal transmission device, comprising: The second receiving module is used to receive a first signal sent by the first device; wherein the first signal is obtained by backscattering modulation based on the information bits to be transmitted and a second signal, and the second signal is the carrier signal of the first signal; the first signal includes at least one first signal unit, each first signal unit includes two CSS symbols, the average power or reflection coefficient of the two CSS symbols is different, and the other parameters of the two CSS symbols are the same except for the average power and reflection coefficient, and the information bits to be transmitted are modulated by the frequency of each CSS symbol in each first signal unit; The calculation module is used to subtract the two CSS symbols in the first signal unit of the first signal to obtain the third signal; The demodulation module is used to demodulate the third signal to obtain the information bits to be transmitted. The apparatus according to claim 21, wherein, The demodulation module is specifically used to perform at least one of the following: The third signal is despread using a reference despread signal to obtain a fourth signal, and the information bits to be transmitted are obtained based on the frequency points of the highest frequency peak or the two highest frequency peaks in the fourth signal. The third signal is demodulated using the maximum likelihood detection algorithm to obtain the information bits to be transmitted. The apparatus according to claim 21 or 22, wherein, The demodulation module is specifically used to: demodulate the third signal according to the obtained fourth information to obtain the information bits to be transmitted; The fourth piece of information includes at least one of the following: The frequency values ​​contained in the frequency pair used for frequency shifting associated with the information bits to be transmitted; The size of the PRB, RBG, and / or BWP of the frequency pair used for frequency shifting associated with the information bits to be transmitted; The modulation method of the first signal; The modulation order of the first signal; The modulation rate of the first signal; The encoding method of the first signal; The coding rate of the first signal; The method of constructing the third signal; The signal parameters of the reference despread signal corresponding to the first signal; wherein, when the frequency sweep mode of the first signal is up-chirp mode, the reference despread signal is conjugate with the CSS signal whose scan start frequency is the lowest frequency; or, when the frequency sweep mode of the first signal is down-chirp mode, the reference despread signal is conjugate with the CSS signal whose scan start frequency is the highest frequency; or, the reference despread signal is conjugate with the first signal; A third index information associated with the demodulation of the first signal, the third index information being used to indicate the associated demodulation parameters. A communication device includes a processor and a memory, the memory storing a program or instructions executable on the processor, the program or instructions, when executed by the processor, implementing the steps of the signal transmission method as claimed in any one of claims 1 to 11, or implementing the steps of the signal transmission method as claimed in any one of claims 12 to 17.

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