WO2024041504A1

WO2024041504A1 - Communication method and device

Info

Publication number: WO2024041504A1
Application number: PCT/CN2023/114177
Authority: WO
Inventors: 李强
Original assignee: 华为技术有限公司
Priority date: 2022-08-26
Filing date: 2023-08-22
Publication date: 2024-02-29

Abstract

Provided are a communication method and device for improving the demodulation performance of a receiving terminal. A receiving terminal receives a first reference signal sent by a sending terminal for frequency offset estimation, and determines a frequency offset estimation value according to the first reference signal; and then the receiving terminal performs frequency offset correction according to the frequency offset estimation value, and receives the signal sent by the sending terminal on a first channel. The frequency domain range of the first reference signal is greater than the frequency domain range of the first channel, and the frequency domain range of the first reference signal comprises the frequency domain range of the first channel. After performing frequency offset estimation on the basis of the first reference signal, the receiving terminal performs frequency offset correction to reduce or eliminate the frequency offset. Therefore, when the first channel receives the signal sent by the sending terminal, the first channel does not receive interference signals from other channels, thereby improving the demodulation performance of the receiving terminal. Meanwhile, since the frequency domain range of the first reference signal is greater than the frequency domain range of the first channel, that is, the frequency domain range of the first reference signal is relatively large while the frequency domain range of the first channel is relatively small, the resource overhead can be saved.

Description

A communication method and device

Cross-references to related applications

This application claims priority to the Chinese patent application submitted to the China Patent Office on August 26, 2022, with application number 202211033223.9 and the application title "A Frequency Offset Estimation Method", the entire content of which is incorporated into this application by reference; This application claims priority to the Chinese patent application filed with the China Patent Office on November 16, 2022, with the application number 202211436792.8 and the application title "A communication method and device", the entire content of which is incorporated into this application by reference.

Technical field

The present application relates to the field of communication technology, and in particular, to a communication method and device.

Background technique

In a wireless communication system, the receiving end needs to filter the signal to filter out signals from other channels and accurately receive the signal of the channel to be received. In order to simplify the implementation, the receiving end generally downconverts the RF signal to the intermediate frequency band, and implements the above filtering in the intermediate frequency band. However, currently using the above method, the demodulation performance at the receiving end is poor.

Contents of the invention

This application provides a communication method and device to improve the demodulation performance of the receiving end.

In the first aspect, this application provides a communication method, which can be applied to the receiving end, a processor, a chip or a functional module in the receiving end. The method may include: the receiving end determines a frequency offset estimate based on the first reference signal after receiving the first reference signal sent by the transmitting end, and then performs frequency offset correction based on the frequency offset estimate, and based on the frequency offset correction result The signal sent by the sending end is received on the first channel. Wherein, the first reference signal can be used for frequency offset estimation, the frequency domain range of the first reference signal is greater than the frequency domain range of the first channel, and the frequency domain range of the first reference signal includes the first The frequency domain range of the channel.

Through the above method, the receiving end performs frequency offset estimation based on the first reference signal and then performs frequency offset correction to reduce or eliminate the frequency offset. Therefore, when receiving the signal sent by the transmitting end on the first channel, it will not receive interference from other channels. signal, thereby improving the demodulation performance of the receiving end. At the same time, since the frequency domain range of the first reference signal is larger than the frequency domain range of the first channel, that is, the frequency domain range of the first reference signal is larger and the frequency domain range of the first channel is smaller, resource overhead can be saved.

In a possible design, the first reference signal may be a signal whose signal frequency changes linearly with time. In this way, the first reference signal can be transmitted and frequency offset estimation can be achieved.

In a possible design, the receiving end determines the frequency offset estimate based on the first reference signal. The method may be: the receiving end may perform filtering processing on the first reference signal to obtain the filtered Reference signal: perform envelope detection on the filtered reference signal to obtain a first envelope signal; the receiving end determines the frequency offset estimate based on the time difference between amplitude peaks of the first envelope signal . In this way, the receiving end can accurately determine the frequency offset estimate based on the time difference between the amplitude peaks of the envelope signal obtained from the first reference signal, and can accurately correct the frequency offset of the carrier frequency signal generated by the local crystal oscillator of the receiving end.

In a possible design, the receiving end determines the frequency offset estimate based on the time difference between amplitude peaks of the first envelope signal. The method may be: the receiving end may determine the frequency offset estimate based on the first envelope signal. The first frequency is determined based on the time difference between the amplitude peaks of the network signal, the transmission duration of the first reference signal, the lowest frequency of the first reference signal and the slope of the first reference signal, and based on the first frequency and the second frequency determine the frequency offset estimate. Wherein, the first frequency is a frequency with frequency offset; the second frequency is a frequency with no frequency offset. Based on the above method, the receiving end can accurately determine the frequency offset estimate based on the first frequency with frequency offset and the second frequency without frequency offset, and then can accurately correct the frequency of the carrier frequency signal generated by the local crystal oscillator of the receiving end. Partial.

In one possible design, the first frequency may conform to the following formula:

Among them, T _interval is the time difference between the amplitude peaks of the first envelope signal, f _low is the lowest frequency of the sweep signal, α is the slope of the first reference signal, T is the transmission duration of the first reference signal, and f is the a frequency.

Among them, T _interval is the time difference between the amplitude peaks of the first envelope signal, f _low is the lowest frequency of the sweep signal, α is the slope of the first reference signal, T is the transmission duration of the first reference signal, and f is the A frequency, Δ is the time domain interval between the frequency rising part and the frequency falling part of the sweep signal.

In a possible design, the first reference signal may be a sequence of at least one on-off keying (OOK) modulation carried on at least one subband, and each subband in the at least one subband At least one subcarrier may be included, and each of the at least one subband may carry at least one OOK modulated sequence. Therefore, the first reference signal can be transmitted through the OOK modulated sequence, thereby achieving frequency offset estimation.

In a possible design, the receiving end determines the frequency offset estimate based on the first reference signal. The method may be: the receiving end performs filtering on the first reference signal to obtain a filtered reference signal. signal, perform envelope detection on the filtered reference signal, and obtain a second envelope signal; furthermore, the receiving end demodulates the second envelope signal, obtains a demodulated signal, and determines the solution The first sub-band corresponding to the modulated signal; finally, the receiving end can determine the frequency offset estimate value according to the first sub-band and the second sub-band, and the second sub-band has no frequency offset. sub-band, the at least one sub-band including the second sub-band. Based on this, the receiving end can accurately determine the frequency offset estimate based on the deviation between the first subband and the second subband, and can accurately correct the frequency offset of the carrier frequency signal generated by the local crystal oscillator of the receiving end. .

In a possible design, the receiving end can also receive a second reference signal sent by the transmitting end, and the second reference signal can be used for frequency offset estimation; the receiving end determines based on the first reference signal The method for the estimated frequency offset value may be: the receiving end determines the estimated frequency offset value based on the first reference signal and the second reference signal. In this way, the receiving end can accurately estimate the frequency offset through the two received reference signals.

In a possible design, the receiving end determines the frequency offset estimate based on the first reference signal and the second reference signal. The method may be: after the receiving end determines the first time difference, based on the The first time difference and the second time difference determine the frequency offset estimate. Wherein, the first time difference is the time difference between when the receiving end receives the first reference signal and when the second reference signal is received; the second time difference is when the sending end sends the first reference signal and The time difference for sending the second reference signal. Through the above method, the receiving end can accurately determine the frequency offset estimate through the deviation between the receiving time difference and the sending time difference between the two reference signals, and can accurately correct the frequency offset of the carrier frequency signal generated by the local crystal oscillator of the receiving end. .

In a possible design, the receiving end may also receive the second time difference sent by the sending end. Then, the receiving end can perform frequency offset estimation based on the first time difference.

In the second aspect, this application provides a communication method, which can be applied to the sending end, a processor, a chip or a functional module in the sending end. The method may include: a sending end sending a first reference signal to a receiving end, and sending a signal on the first channel to the receiving end. Wherein, the first reference signal can be used for frequency offset estimation; the frequency domain range of the first reference signal is greater than the frequency domain range of the first channel, and the frequency domain range of the first reference signal includes the first The frequency domain range of the channel.

Through the above method, the receiving end can perform frequency offset estimation based on the first reference signal to reduce or eliminate the frequency offset. Therefore, when receiving the signal sent by the transmitting end on the first channel, it will not receive interference signals from other channels, thus Improve the demodulation performance of the receiving end. At the same time, since the frequency domain range of the first reference signal is larger than the frequency domain range of the first channel, that is, the frequency domain range of the first reference signal is larger and the frequency domain range of the first channel is smaller, resource overhead can be saved.

In a possible design, the first reference signal may be at least one OOK modulated sequence carried on at least one subband, and each subband of the at least one subband may include at least one subcarrier. Each of the at least one subband may carry at least one OOK modulated sequence. In this way, the first reference signal can be transmitted through the OOK modulated sequence and frequency offset estimation can be achieved.

In a possible design, the transmitting end may send a second reference signal to the receiving end, and the second reference signal is used for frequency offset estimation. So that the receiving end can perform frequency offset estimation based on the first reference signal and the second reference signal.

In a possible design, the sending end may send a second time difference to the receiving end, where the second time difference is the time difference between the sending end sending the first reference signal and the second reference signal. So that the receiving end can realize the frequency offset estimation by combining the time difference between when the receiving end receives the first reference signal and when the receiving end receives the second reference signal.

In a third aspect, this application also provides a communication device. The communication device may be a receiving end. The communication device has the ability to implement the above Functionality of a method in the first aspect or in each possible design example of the first aspect. The functions described can be implemented by hardware, or can be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions.

In one possible design, the structure of the communication device includes a transceiver unit and a processing unit. These units can perform the corresponding functions in the above-mentioned first aspect or each possible design example of the first aspect. For details, see the method examples. Detailed description will not be repeated here.

In a possible design, the structure of the communication device includes a transceiver and a processor, and optionally a memory. The transceiver is used to send and receive signals, and to communicate and interact with other devices in the communication system. The processor is configured to support the communication device to perform corresponding functions in the above-mentioned first aspect or each possible design example of the first aspect. The memory is coupled to the processor and holds program instructions and data necessary for the communications device.

Optionally, the transceiver may include a receiver, and the receiver may include a first intermediate frequency filter and a second intermediate frequency filter, and the frequency domain range of the first intermediate frequency filter is smaller than that of the second intermediate frequency filter. frequency domain range, wherein the first intermediate frequency filter can be used to filter the received reference signal (such as the first reference signal), and the second intermediate frequency filter can be used to filter the received signal of the first channel. Perform filtering.

In a fourth aspect, the present application also provides a communication device, which may be a sending end. The communication device has the function of implementing the method in the above-mentioned second aspect or each possible design example of the second aspect. The functions described can be implemented by hardware, or can be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions.

In one possible design, the structure of the communication device includes a transceiver unit and a processing unit. These units can perform the corresponding functions in the above second aspect or each possible design example of the second aspect. For details, see the method examples. Detailed description will not be repeated here.

In a possible design, the structure of the communication device includes a transceiver and a processor, and optionally a memory. The transceiver is used to send and receive signals, and to communicate and interact with other devices in the communication system. The processor is configured to support the communication device to perform corresponding functions in the above-mentioned second aspect or each possible design example of the second aspect. The memory is coupled to the processor and holds program instructions and data necessary for the communications device.

In the fifth aspect, embodiments of the present application provide a communication system, which may include the above-mentioned receiving end and transmitting end.

In a sixth aspect, embodiments of the present application provide a computer-readable storage medium. The computer-readable storage medium stores program instructions. When the program instructions are run on a computer, they cause the computer to execute the first aspect of the embodiments of the application and its contents. any possible design, or the method described in the second aspect and any possible design thereof. By way of example, computer-readable storage media can be any available media that can be accessed by a computer. Taking this as an example but not limited to: computer-readable media may include non-transitory computer-readable media, random-access memory (random-access memory, RAM), read-only memory (read-only memory, ROM), electrically erasable memory In addition to programmable read-only memory (electrically EPROM, EEPROM), CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or can be used to carry or store the desired program code in the form of instructions or data structures and can Any other media accessed by a computer.

In a seventh aspect, embodiments of the present application provide a computer program product that includes computer program code or instructions. When the computer program code or instructions are run on a computer, the first aspect or any of the possible designs of the first aspect are enabled. , or the method described in the above second aspect or any possible design of the second aspect is executed.

In an eighth aspect, the present application also provides a chip, including a processor, the processor being coupled to a memory and configured to read and execute program instructions stored in the memory, so that the chip implements the above-mentioned first aspect Or any possible design of the first aspect, or the method described in the above second aspect or any possible design of the second aspect.

For each aspect in the above-mentioned third to eighth aspects and the technical effects that may be achieved by each aspect, please refer to the above-mentioned first aspect or various possible solutions in the first aspect, or the above-mentioned second aspect or each possible solution in the second aspect. The description of the technical effects that can be achieved by this possible solution will not be repeated here.

Description of drawings

Figure 1a is a schematic architectural diagram of a communication system provided by this application;

Figure 1b is a schematic diagram of the architecture of a communication system provided by this application;

Figure 2 is a schematic diagram of amplitude modulation and envelope detection provided by this application;

Figure 3 is a schematic diagram of OOK modulation provided by this application;

Figure 4 is a schematic structural diagram of an OOK receiver provided by this application;

Figure 5 is a schematic diagram of using an OFDM system to send OOK signals provided by this application;

Figure 6 is a schematic diagram of down conversion with frequency offset provided by this application;

Figure 7 is a schematic diagram of increasing the bandwidth of the transmitted signal to solve the frequency offset provided by this application;

Figure 8 is a flow chart of a communication method provided by this application;

Figure 9 is a schematic diagram of periodic transmission of a first reference signal provided by this application;

Figure 10 is a schematic diagram in which the first reference signal provided by this application is a frequency sweep signal;

Figure 11 is a schematic diagram of the time domain waveform of a frequency sweep signal provided by this application;

Figure 12 is a schematic diagram showing that another first reference signal provided by this application is a frequency sweep signal;

Figure 13 is a schematic diagram of the intersection of sweep frequency and filtering frequency provided by this application;

Figure 14 is another schematic diagram of the intersection of sweep frequency and filtering frequency provided by this application;

Figure 15 is a schematic diagram of an OFDM transmitter carrying different OOK modulation sequences on different subbands provided by this application;

Figure 16 is a schematic diagram of a first reference signal provided by this application;

Figure 17 is a schematic diagram of the instantaneous frequency of a first reference signal provided by this application;

Figure 18 is a schematic diagram showing that an envelope signal provided by this application has two amplitude peaks;

Figure 19 is a schematic diagram of a sending end sending two reference signals to a receiving end provided by this application;

Figure 20 is a schematic structural diagram of a receiver provided by this application;

Figure 21 is a schematic structural diagram of a communication device provided by this application;

Figure 22 is a structural diagram of a communication device provided by this application.

Detailed ways

The present application will be described in further detail below with reference to the accompanying drawings.

Embodiments of the present application provide a communication method and device to improve the demodulation performance of the receiving end. Among them, the method and the device described in this application are based on the same technical concept. Since the principles of solving problems by the method and the device are similar, the implementation of the device and the method can be referred to each other, and the repeated parts will not be repeated.

In the description of this application, words such as "first" and "second" are only used for the purpose of differentiating the description, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order.

In the description in this application, "at least one (species)" refers to one (species) or multiple (species), and multiple (species) refers to two (species) or more than two (species). "At least one of the following" or similar expressions thereof refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can mean: a, b, c, a and b, a and c, b and c, or a, b and c, where a, b, c Can be single or multiple.

"And/or" in the description of this application describes the relationship between associated objects, indicating that there can be three relationships, for example, A and/or B, which can mean: A exists alone, A and B exist simultaneously, and B exists alone. situation, where A and B can be singular or plural. "/" means "or", for example, a/b means a or b.

The communication method provided by the embodiments of this application can be applied to various communication systems. For example, the communication method of the embodiment of the present application can be applied to the third generation (3th generation, 3G) communication system, the fourth generation (4th generation, 4G) communication system, the fifth generation (5th generation, 5G), and the future sixth generation. Generation (6th generation, 6G) communication system or other systems, etc. The communication method of the embodiment of the present application can also be applied to short-distance wireless communication systems such as sidelink, wireless fidelity (wireless fidelity, wifi), and Bluetooth.

Exemplarily, Figures 1a and 1b show the architecture of a possible communication system to which the communication method provided by this application is applicable.

The architecture of the communication system shown in Figure 1a may include network equipment and terminal equipment. Among them, the network equipment can send downlink signals to the terminal equipment, and the network equipment and the terminal equipment can support envelope detection modulation technology.

The architecture of the communication system shown in Figure 1b may include at least two terminal devices (for example, terminal device 1 and terminal device 2 in Figure 1b). At least two terminal devices send signals to each other. For example, the two terminal devices can transmit signals to each other through Sidelinks send signals to each other. At least two terminal devices can support envelope detection modulation technology.

The above network device may be a device that provides access to terminal devices. The network device may be a radio access network (RAN) device, such as a base station. Network equipment may also refer to equipment that communicates with terminal equipment over the air interface. The network equipment may include an evolved Node B (eNB or e-NodeB) in a long term evolution (long term evolution, LTE) system or long term evolution-advanced (LTE-A). The network device can also be a new radio controller (new radio controller, NR controller), which can be a base station (gNode B, gNB) in the 5G system, a centralized network element (centralized unit), a new wireless base station, a radio frequency remote module, or a micro base station (also known as Small station), which can be a relay, a distributed unit, various forms of macro base stations, a transmission reception point (TRP), a transmission measurement function (transmission measurement function (TMF) or transmission point (TP) or any other wireless access device. The embodiments of the present application are not limited thereto. The network equipment may also include at least one of the following: radio network controller (RNC), Node B (NB), base station controller (BSC), base transceiver station, BTS), home base station (for example, home evolved NodeB, or home Node B, HNB), base band unit (base band unit, BBU), radio frequency remote unit (remote radio unit, RRU), wifi access point (access point, AP) or the baseband pool (BBU pool) in the cloud radio access netowrk (CRAN), etc. The embodiments of this application do not limit the specific technologies and specific equipment forms used by network equipment. For example, a network device may correspond to an eNB in a 4G system and a gNB in a 5G system.

In this application, the network device can also be a functional module, chip or chip system. Optionally, the functional module, chip or chip system can be disposed in the network device.

The above terminal equipment can also be called user equipment (UE), mobile station (MS), mobile terminal (MT), etc. It is a device that provides voice and/or data connectivity to users. equipment. For example, the terminal device may include a handheld device with a wireless connection function, a vehicle-mounted device, etc. Currently, terminal devices can be: mobile phones, tablets, laptops, PDAs, mobile Internet devices (MID), wearable devices, virtual reality (VR) devices, augmented reality ( augmented reality (AR) equipment, XR equipment, MR equipment, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical surgery, intelligent Wireless terminals in the power grid (smart grid), wireless terminals in transportation safety (transportation safety), wireless terminals in smart cities (smart city), or wireless terminals in smart homes (smart home), etc.

Terminal equipment can also be device-to-device communication (device-to-device, D2D) terminal equipment, Internet of Vehicles V2X communication terminal equipment, smart vehicles, vehicle-to-machine systems (or Internet of Vehicles systems) (telematics box, TBOX), machine to Machine-to-machine/machine-type communications (M2M/MTC) terminal equipment, Internet of things (IoT) terminal equipment. For example, the terminal device may be a vehicle, ship or aircraft, or a terminal-type roadside unit, or a communication module or chip built into the vehicle or roadside unit. For example, the terminal device can be a vehicle-mounted module. The terminal equipment can also be a road side unit (RSU). If the various terminal devices introduced above are located on the vehicle, such as placed or installed in the vehicle, they can be considered as vehicle-mounted terminal equipment. The vehicle-mounted terminal equipment is also called an on-board unit (OBU), for example.

As an example and not a limitation, in this embodiment of the present application, the terminal device may also be a wearable device. Wearable devices can also be called wearable smart devices or smart wearable devices. It is a general term for applying wearable technology to intelligently design daily wear and develop wearable devices, such as glasses, gloves, watches, clothing and shoes. wait. A wearable device is a portable device that is worn directly on the body or integrated into the user's clothing or accessories. Wearable devices are not just hardware devices, but also achieve powerful functions through software support, data interaction, and cloud interaction. Broadly defined wearable smart devices include full-featured, large-sized devices that can achieve complete or partial functions without relying on smartphones, such as smart watches or smart glasses, and those that only focus on a certain type of application function and need to cooperate with other devices such as smartphones. Used, such as various smart bracelets, smart helmets, smart jewelry, etc. for physical sign monitoring.

Terminal devices can also be smart devices such as amusement equipment, smart appliances, or drones.

In this application, the terminal device may be, for example, the terminal device itself, or a module used to implement the functions of the terminal device, such as a chip or a chip system, and the chip or chip system may be provided in the terminal device.

For ease of understanding, some technical terms involved in the embodiments of this application are first explained below:

1) Envelope detection receiver

In communication systems, under certain modulation methods, some signals can be received by envelope detection receivers, such as amplitude modulation (AM) broadcasting.

Generally, wireless communication systems need to use a carrier frequency. Assuming that the carrier frequency of the transmitted signal is f _c , the carrier signal can be expressed as cos(2πf _c t+φ ₀ ), and φ ₀ is the initial phase of the carrier frequency. If the signal to be transmitted is modulated in amplitude, assuming that the signal to be transmitted is s _AM (t), then the actual signal sent can be recorded as s _AM (t)·cos(2πf _c t+φ ₀ ), after modulation The waveform of the signal can be a modulated waveform as shown in Figure 2.

At the receiving end, the modulated signal needs to be demodulated, which is s _AM (t). This can be achieved through envelope detection. The so-called envelope detection uses a detection circuit to extract the envelope of the radio frequency (RF) signal waveform, as shown in the outline curve of the radio frequency (RF) signal in Figure 2. From this, it can be seen that the envelope The network is the modulated signal s _AM (t).

The advantages of envelope detection are simplicity and low power consumption, and it can be used in some communication devices that have requirements on cost or power consumption, such as Internet of Things devices.

Modulation techniques that can use envelope detection can include the following modulation methods: amplitude modulation (AM), on-off keying (ON-OFF-keying), amplitude shift keying (ASK), etc.

2)OOK modulation

OOK modulation is a simple modulation method. This modulation method uses whether or not a signal is sent to convey information.

OOK modulation first uses on-off non-return-to-zero line code (ON-OFF NRZ line code) to generate a baseband waveform according to the information that needs to be modulated. Among them, the ON-OFF NRZ line code uses a high level to represent the information bit (bit) "1", and a zero level to represent the information bit "0", as shown in Figure 3, for example. The signal generated based on the above operation can be expressed as s _nrz (t).

Then, the carrier signal is multiplied by s _nrz (t) to generate the OOK signal. Assuming that the carrier frequency of the transmitted signal is f _c , the carrier signal can be expressed as cos(2πf _c t+φ ₀ ), and φ ₀ is the initial phase of the carrier frequency. Then the generated OOK signal can conform to the formula: s _OOK (t) = s _nrz (t) cos (2πf _c t + φ ₀ ), and its waveform can be seen in the lower waveform in Figure 3. It can be understood that OOK modulation sends a signal when the information that needs to be sent is '1', and does not send a signal when the information that needs to be sent is '0'.

At the receiving end, the receiver only needs to determine whether there is energy in a symbol to determine whether the transmitted signal is '0' or '1', thereby completing demodulation.

3)OOK envelope detection receiver

OOK modulation can also be demodulated using an envelope detector.

For example, in Figure 4, the structure of a commonly used OOK receiver is shown. Here, it is assumed that the OOK signal is transmitted at a radio frequency (f _RF =3.5GHz). At the receiving end, radio frequency filtering is first performed through a radio frequency bandpass filter (RF BPF) to suppress out-of-band signals, and then a radio frequency amplifier (such as a radio frequency low noise amplifier (RF low noise amplifier, RF LNA)) amplifies the filtered signal. Thereafter, a local carrier signal is generated through a local crystal oscillator (LO), mixed with the amplified radio frequency signal, and then the frequency of the signal is moved to an intermediate frequency (IF). In this example, as shown in Figure 4, it is assumed that the IF frequency is f _IF =50MHz. At the intermediate frequency, after amplifying and band-pass filtering the signal, the OOK signal at the intermediate frequency can be obtained. Finally, after envelope detection through an envelope detector, the envelope waveform of the signal can be obtained, and OOK demodulation can be performed based on the amplitude of the envelope waveform.

Shown in Figure 4 is the receiver structure that downconverts the RF signal to an intermediate frequency. The reason why the radio frequency needs to be down-converted to the intermediate frequency is because the receiving end needs to filter the target signal, filter out the signals of other channels, and receive the signal of the target channel. The filter is difficult to implement in the radio frequency band, but it is easier to implement in the intermediate frequency band. Receiver structures with intermediate frequencies are commonly used in wireless communication systems.

The envelope signal of the OOK signal is a modulated ON-OFF NRZ baseband waveform, and the OOK signal can be demodulated through the envelope signal.

4) Orthogonal frequency division multiplexing (OFDM)

OFDM modulation is another widely used modulation technology. OFDM modulation is generally used in mobile broadband systems to utilize higher communication bandwidth to provide high transmission rates.

In OFDM modulation, the system bandwidth can be divided into multiple parallel sub-carriers, and data is modulated separately on each sub-carrier for transmission. Each sub-carrier has a different frequency. In the OFDM transmission and reception process, first, the data to be transmitted is mapped into a complex symbol through modulation. The complex symbol can be written as a is the amplitude of the symbol, is the phase of the symbol. Optionally, the modulation will use quadrature amplitude modulation (QAM) mapping to map the information into a QAM symbol (the QAM symbol is also a complex symbol). Then, through serial-to-parallel conversion, each QAM symbol is mapped to different subcarriers. Symbols on different subcarriers are input into an inverse fast fourier transform (IFFT), which performs a fast inverse Fourier operation and is converted into a time domain sequence.

In conventional OFDM symbol processing, the tail part of the time domain sequence is copied to the front end of the signal, which is called cyclic prefix (CP). The main function of the cyclic prefix is to combat the multipath transmission delay in the wireless channel. After completing the cyclic prefix addition, the transmitter will perform digital to analog conversion on the signal and perform up-conversion before transmitting.

5) Use OFDM system to send OOK signal

In current cellular mobile communication networks, OFDM modulation technology is usually used. The main purpose of the cellular mobile communication network is to provide mobile broadband (MBB) services, such as using mobile phones, tablets and other terminal devices for high-speed Internet access, video browsing, file downloading, etc.

However, in recent years, there has been a trend of diversification in the services provided by cellular mobile communication networks. Many terminal devices, such as IoT devices, wearable devices (smart watches), low power wake up radios, etc., The required communication rate is very low, but There are high requirements for low cost and low power consumption of receivers. For these terminal devices, OFDM is not a suitable modulation method because the OFDM receiver requires precise time-frequency synchronization and complex signal processing, which requires high cost and power consumption. Therefore, the industry considers using simpler modulation methods to serve these devices, such as OOK, which is a better choice.

In order to serve the purpose of serving different types of terminal equipment, one approach is to set up two sets of transmitters on the base station of the mobile communication network. One set is used to send OFDM signals to serve mobile broadband users, and the other set is used to send OOK signals. Serving low-speed users. However, this approach requires hardware upgrade of existing network equipment, that is, adding a set of OOK transmitters based on the existing OFDM transmitter. This will bring great costs to network deployers.

Another approach is that the transmitter still uses the existing OFDM transmitter structure, but uses some signal processing methods to generate other modulation waveforms in certain frequency bands. For example, OFDM transmitters can generate OOK modulation waveforms on certain frequency bands.

For example, as shown in Figure 5, 37 OFDM symbols are sent here, and each OFDM symbol shows 22 subcarriers. It is assumed that the subcarriers in the diagonally filled part are used to serve mobile broadband services, and the middle 5 subcarriers (subcarriers) are Carriers 8-12) serve low-speed services. At this time, when "ON" symbols need to be sent, 5 subcarrier modulation signals are sent, such as the black OFDM symbols in Figure 5. When "OFF" symbols need to be sent, no data is modulated. As shown in the white OFDM symbol in Figure 5, after the receiving end uses a filter to filter out these five subcarriers, the time domain waveform is actually the OOK signal. In this way, only the software of the transmitter needs to be upgraded, and the OFDM transmitter can be used to generate waveforms of other modulation technologies.

6) Frequency offset problem of IF receiver

In the receiver structure shown in Figure 4 above, a local crystal oscillator is needed to downconvert the RF signal to an intermediate frequency. However, some terminal equipment, due to cost or power consumption considerations, will use local crystal oscillators with poor stability. At this time, the carrier signal generated by the crystal oscillator may deviate from the ideal frequency. Sometimes, the frequency deviation will be large. In this way, the waveform of the target channel (that is, the channel that needs to receive the signal) cannot be accurately converted to the passband range of the filter, resulting in a loss of signal energy, which may convert the signal transmitted in the adjacent band to the passband range of the filter. , causing interference and thus affecting demodulation performance.

For example, as shown in Figure 6, the black part shown in Figure 6 is the spectrum of the signal to be received (which can be understood as the signal of the target channel, or also called the target signal), and the white part is the signal transmitted on the adjacent channel. Figure 6 (a) shows that when the frequency offset generated by the local crystal oscillator is very small, after down-conversion, the spectrum of the target channel will be accurately migrated to the set intermediate frequency, and the spectrum of the signal will accurately fall into The bandwidth range of the IF filter. After filtering, the signal of the target channel will be retained, while the signal on the adjacent band channel will be filtered out.

However, if the local crystal oscillator produces a large frequency deviation, there will be a frequency deviation after downconversion. As shown in (b) in Figure 6, when the frequency offset is large, the spectrum of the target channel cannot be accurately migrated to the intermediate frequency, and the filter will filter out part of the target signal. In addition, part of the signals on the adjacent channel will Passes through the filter and enters the subsequent processing of the receiver, causing interference.

To address the above frequency offset problem, one current solution is to increase the bandwidth of the transmitted signal (which can also be understood as the bandwidth of the target channel) so that it exceeds the bandwidth of the IF filter. In this way, even if there is a scenario with a large frequency offset, the spectrum of the adjacent band signal will still not enter the passband range of the filter and will not cause adjacent band interference. For example, as shown in Figure 7, the bandwidth of the target channel can be set larger, and the filter bandwidth of the receiver is smaller than the bandwidth of the target channel. In this way, even if there is a frequency offset, the signal received within the bandwidth of the filter is still the signal of the target channel, and no interference signal on the adjacent band will be received. However, although the above method can solve the interference problem caused by frequency offset, it will cause a waste of spectrum resources.

Based on this, embodiments of the present application propose a communication method to solve the frequency offset problem existing at the receiving end, reduce interference, and improve demodulation performance.

In the following embodiments, the communication method provided by the embodiments of the present application is described in detail by taking the sending end and the receiving end as examples. It should be understood that the operations performed by the sending end can also be performed by the processor in the sending end, or by a chip or chip system. , or implemented by a functional module, etc. The operations performed by the receiving end can also be implemented by a processor in the receiving end, or a chip or chip system, or a functional module, etc. This application is not limited to this.

Optionally, the sending end can be a network device, and the receiving end can be a terminal device. Or, optionally, the sending end may be a terminal device, and the receiving end may be a terminal device, which is not limited in this application.

Based on the above description, the embodiment of the present application provides a communication method, as shown in Figure 8. The process of the method may include:

801: The sending end sends the first reference signal to the receiving end.

Wherein, the first reference signal can be used for frequency offset estimation; the frequency domain range of the first reference signal is greater than the frequency domain range of the first channel, and the frequency domain range of the first reference signal includes the first The frequency domain range of the channel.

Correspondingly, the receiving end receives the first reference signal sent by the transmitting end.

The frequency domain range can also be described as bandwidth, which is not limited in this application.

802: The receiving end determines a frequency offset estimate based on the first reference signal.

803: The receiving end performs frequency offset correction according to the frequency offset estimate value.

Exemplarily, the frequency offset correction performed by the receiving end based on the frequency offset estimated value may specifically include: the receiving end compensates the frequency of the carrier signal generated by the local crystal oscillator of the receiver based on the frequency offset estimated value; or , the receiving end adjusts the frequency multiplication coefficient of the frequency multiplication circuit of the receiver based on the frequency offset estimated value; or, the receiving end generates a frequency offset compensation signal based on the frequency offset estimated value.

804: The receiving end receives the signal sent by the transmitting end on the first channel based on the frequency offset correction result.

Correspondingly, the sending end sends a signal to the receiving end on the first channel.

Optionally, when the receiving end compensates the frequency of the carrier signal generated by the local crystal oscillator based on the estimated frequency offset value or adjusts the frequency multiplication coefficient of the frequency multiplication circuit of the receiver, the result of the frequency offset correction is that the frequency offset of the receiving end is corrected , therefore the receiving end can receive the signal sent by the transmitting end on the first channel without frequency offset or with a small frequency offset.

Optionally, in the case where the receiving end generates a frequency offset compensation signal based on the frequency offset estimate, when the receiving end receives the signal sent by the transmitting end on the first channel based on the frequency offset correction result, the received end may be The signal and the frequency offset compensation signal are multiplied to obtain a signal with no frequency offset or a small frequency offset (which can be called a correction signal). Among them, the multiplication of the received signal and the frequency offset compensation signal can be realized through a multiplication circuit.

Through the above method, the receiving end performs frequency offset estimation based on the first reference signal and then performs frequency offset correction to reduce or eliminate the frequency offset, so that when receiving the signal sent by the transmitting end on the first channel, it will not receive interference from other channels. signal, thereby improving the demodulation performance of the receiving end. At the same time, since the frequency domain range of the first reference signal is larger than the frequency domain range of the first channel, that is, the frequency domain range of the first reference signal is larger and the frequency domain range of the first channel is smaller, resource overhead can be saved.

Specifically, the frequency deviation of the crystal oscillator in the receiver (called frequency offset) is mainly affected by frequency drift. Frequency drift means that due to environmental influences such as temperature, the frequency generated by the crystal oscillator deviates from the designed frequency within a period of time. This deviation itself is relatively stable within a period of time. For example, within a few seconds, the size of the frequency deviation changes little. Based on this, in the above method, the receiving end estimates the size of the frequency offset and compensates for the frequency of the carrier signal generated by the crystal oscillator. The frequency offset can be corrected to a smaller frequency offset, thereby reducing signal interference in adjacent bands. . After a frequency offset correction, the frequency offset can be kept small for a period of time, because the size of the frequency drift is stable for a period of time, so the frequency offset of the receiver is maintained at a relatively small level through frequency offset estimation and frequency offset correction. low level. Optionally, the receiving end can periodically perform frequency offset estimation and frequency offset correction to maintain the frequency offset of the receiver at a low level.

In an optional implementation, the first reference signal may be sent periodically or aperiodicly. For example, FIG. 9 shows a schematic diagram of periodic transmission of the first reference signal. For example, as shown in Figure 9, the frequency domain range of the first reference signal is W1, and the frequency domain range of the first channel is W2. It can be seen that W1 is greater than W2, and W1 includes W2. The first reference signal used for frequency offset estimation has a larger frequency domain range and can accommodate larger frequency offsets to accurately achieve frequency offset estimation.

For example, the frequency domain range of the first channel may be greater than or equal to the frequency domain range of the intermediate frequency filter of the receiver, which can save resource overhead. For example, Wf shown in an exemplary manner in FIG. 9 is the frequency domain range of the IF filter of the receiver, and Wf is shown in an exemplary manner smaller than W2 in FIG. 9 .

Combined with the example shown in Figure 9, at time t1, the receiver has a large frequency offset. As shown in Figure 9, the frequency domain range Wf of the IF filter of the receiver is located above the frequency domain range W1 of the first reference signal. position, but because the frequency domain range of the first reference signal is large, even if there is a large frequency offset, the receiving end will still not receive the interference signal in the adjacent band. After the receiving end estimates the frequency offset based on the first reference signal, it can adjust the frequency of the carrier signal generated by the local crystal oscillator so that the frequency offset of the receiver can be corrected. As shown at time t2 in Figure 9, after the frequency offset is corrected, the intermediate frequency of the receiver The frequency domain range Wf of the filter basically matches the frequency domain range of the first channel. Although at this time, the frequency domain range of the first channel is W2, which is lower than the frequency domain range W1 of the first reference signal, because the frequency offset of the receiver has been corrected, there will be no problem of adjacent band interference. . After a frequency offset correction is completed, the receiver can maintain a small frequency offset for a period of time, such as at t3 and t4. Although the receiving end has some frequency drift, it is still basically within the frequency domain of the first channel. . Until time t5, the frequency offset is already large, but at the same time, it has also entered the time of sending the first reference signal. Therefore, after repeating the previous steps to estimate and correct the frequency offset, the frequency offset can be compensated (time t6), and thereafter In turn, a narrower frequency domain range W2 can be used to transmit signals.

From the above, it can be seen that the receiving end performs frequency offset estimation based on the first reference signal and then performs frequency offset correction, which can reduce or eliminate the frequency offset. Therefore, when receiving the signal sent by the transmitting end on the first channel, it will not receive interference from other channels. signal, thereby improving the demodulation performance of the receiving end. At the same time, compared to the case where the frequency domain ranges of the first reference signal and the first channel are both large, resource overhead can be saved.

Optionally, the above-mentioned first reference signal can be implemented in the following two ways:

In mode a1, the first reference signal may be a signal whose signal frequency changes linearly with time.

For example, a signal whose signal frequency changes linearly with time may include a frequency sweep signal or the like. In the following description, in mode a1, the A reference signal is illustrated by taking a frequency sweep signal as an example. It should be understood that this does not limit the present application.

In an example, the frequency sweep signal may be a signal whose frequency goes from low to high and then to low again, or the frequency sweep signal may be a signal which goes from high to low and then to high frequency. For example, FIG. 10 shows a schematic diagram in which the first reference signal is a frequency sweep signal. In FIG. 10 , the frequency of the frequency sweep signal goes from low to high and then to low again, and the frequency domain range of the frequency sweep signal is W1. Optionally, the time domain waveform of the frequency sweep signal shown in Figure 10 can be as shown in Figure 11. It can be seen from Figure 11 that the frequency domain of the frequency sweep signal is from low to high, and then from high to low.

Optionally, the frequency sweep signal can conform to the following formula 1:

Among them, s _fmcw,n+1 (t) is the frequency sweep signal at time t, f _low is the lowest frequency of the frequency sweep signal, α is the slope of the frequency sweep signal, T is the duration of the frequency sweep signal, and n is the frequency sweep signal The order of the waveforms, the rising period is the rising period of the frequency sweep signal, and the falling period is the falling period of the frequency sweep signal.

As another example, Figure 12 shows another schematic diagram in which the first reference signal is a frequency sweep signal. In Figure 12, the frequency of the frequency sweep signal goes from low to high and then to low again. The frequency domain range of the frequency sweep signal is W1, relative to The difference between the frequency sweep signal in Figure 10 and the frequency sweep signal in Figure 12 is that there is a time domain interval Δ between the frequency rising part and the frequency falling part of the frequency sweep signal in Figure 12 .

In this method a1, the receiving end determines the frequency offset estimate value based on the first reference signal. The method may be: the receiving end performs filtering on the first reference signal to obtain a filtered reference signal; the receiving end performs filtering on the filtered reference signal. Envelope detection is performed to obtain the first envelope signal; the receiving end determines the frequency offset estimate based on the time difference between the amplitude peaks of the first envelope signal.

For example, when the frequency sweep signal is sent as the first reference signal, when the receiving end filters the frequency sweep signal, the frequency of the frequency sweep signal will intersect with the filtering frequency of the receiving end filter at two moments, as shown in Figure 13 and the left panel in Figure 14. During the intersection time, more energy will pass through the filter, while at other times, because no sweep signal passes through the filter, the output energy of the filter is lower.

Figure 13 shows a schematic diagram of the intersection of the sweep frequency and the filtering frequency in the two cases of frequency offset 1 and frequency offset 2. Figure 14 shows a schematic diagram of the intersection of the sweep frequency and the filtering frequency when there is a frequency offset of 1. From Figure 13, it can also be seen that with different frequency offsets, the intersection time intervals are different, and there is a corresponding relationship between the interval between intersection times and the size of the frequency offset. For example, when the frequency after frequency offset is larger than the frequency without frequency offset, the larger the intersection time interval is, the greater the frequency offset is; when the frequency after frequency offset is smaller than the frequency without frequency offset, The larger the intersection time interval, the smaller the frequency deviation.

Further, after the receiving end obtains the first envelope signal, the first envelope signal has two amplitude peaks (ie, two wave peaks), for example, as shown in the right diagrams in Figures 13 and 14 . Furthermore, the receiving end can detect the time difference between the amplitude peaks of the first envelope signal, and the frequency offset estimate can be determined through the time difference.

Optionally, the receiving end determines the frequency offset estimate based on the time difference between the amplitude peaks of the first envelope signal. The method may be: the receiving end may determine the frequency offset estimate based on the time difference between the amplitude peaks of the first envelope signal, the first reference The transmission duration of the signal, the lowest frequency of the first reference signal and the slope of the first reference signal determine the first frequency, which is the frequency with frequency offset; then, the receiving end determines the frequency offset based on the first frequency and the second frequency. The estimated value, the second frequency is the frequency where there is no frequency offset. For example, the difference between the first frequency and the second frequency is the frequency offset estimate.

In one example, the first frequency may conform to the following formula 2:

In another example, the first frequency can also conform to the following formula three:

Optionally, the above-mentioned second frequency may be predefined. Alternatively, the sending end broadcasts the second frequency, and the receiving end can receive the second frequency.

Mode a2: The first reference signal may be at least one OOK modulated sequence carried on at least one subband. Each subband of includes at least one subcarrier, and each subband of the at least one subband carries at least one OOK modulated sequence.

In this method a2, the first reference signal may be a signal sent by the transmitting end based on the OFDM transmitter. For example, the transmitter can carry different OOK modulated sequences on different subbands through the OFDM transmitter.

Optionally, the receiving end determines the frequency offset estimate based on the first reference signal. The method may be as follows: first, the receiving end performs filtering on the first reference signal to obtain a filtered reference signal; the receiving end performs filtering on the filtered reference signal. Envelope detection is performed to obtain the second envelope signal; then, the receiving end demodulates the second envelope signal to obtain the demodulated signal, and determines the first subband corresponding to the demodulated signal; the receiving end performs envelope detection according to the first The first subband and the second subband determine the frequency offset estimate, the second subband is a subband without frequency offset, and the above-mentioned at least one subband includes the second subband. The demodulated signal is the OOK modulated sequence carried on the first subband.

Optionally, the frequency difference between the first subband and the second subband is the frequency offset estimate.

In this way, since different subbands modulate different sequences, the receiving end will demodulate different OOK modulated sequences at different frequency offsets, and the size of the frequency offset can be determined.

For example, as shown in Figure 15, it is assumed that OFDM symbols 0-3 are used to transmit the first reference signal, and OFDM symbols 4-36 are used to transmit the signal of the first channel. When the first reference signal is transmitted, it occupies a frequency domain range of 15 subcarriers (subcarriers 3-17), and during the signal transmission time of the first channel, it occupies a frequency domain range of 5 subcarriers (subcarriers 8-12).

On the time-frequency resource for transmitting the first reference signal, each subband carries a different OOK modulated sequence, for example, subcarrier 3, the modulated sequence is "OFF OFF OFF OFF ON", or written as "0001" in the form of a bit string, For subcarrier 4, the modulation sequence is "0010", and other subcarriers are similar.

When there is no frequency offset in the receiver, the filter can work at the intermediate frequency point, such as subcarrier 10 in Figure 15 (that is, the second subband). At this time, after envelope detection and demodulation at the receiving end, the The bit sequence is "1000". Optionally, when there is no frequency offset, the sequence obtained by demodulation at the receiving end is predefined. If there is a frequency offset, the filter will filter out the signals of other subcarriers. Assuming that the sequence obtained after demodulation at the receiving end is "1011", it can be judged that the currently demodulated subband corresponds to subcarrier 13 (i.e. the 13th subcarrier). One belt). From this, the receiving end can determine that there are currently three subcarrier frequency offsets, that is, the receiving end can determine the frequency offset estimate.

In this method a2, in a possible example, when sending the first reference signal, the transmitting end can generate a signal similar to a frequency sweep signal based on the OFDM transmitter, such as the schematic diagram of the first reference signal shown in Figure 16. The first reference signal shown in Figure 16 occupies a length of 15 OFDM symbols, in which OFDM symbol 0 modulates the sequence on subcarrier No. 0, OFDM symbol 1 modulates the sequence on subcarrier No. 1, and so on, until OFDM symbol 7 The sequence is modulated on subcarrier No. 7, and further between OFDM symbol 7 and OFDM symbol 14, the subcarrier numbers of the modulation sequence are reduced one by one. Through the above method, the instantaneous frequency of the first reference signal can be as shown in Figure 17. Compared with the sweep signal in the above method a1, the instantaneous frequency of the first reference signal in the method a2 is in a demodulated shape instead of a ramp shape.

Similarly, after the receiving end performs filtering and envelope detection on the first reference signal, the resulting envelope signal will still have two amplitude peaks, as shown in Figure 18, for example. Furthermore, the receiving end can determine the frequency offset estimate based on the distance between the two amplitude peaks. Among them, the method in which the receiving end can determine the estimated frequency offset value based on the distance between the two amplitude peaks is similar to the method in which the receiving end determines the estimated frequency offset value based on the time difference between the amplitude peak values of the first envelope signal in the above method a1. , can refer to each other and will not be described in detail here.

The above describes two implementation methods of the first reference signal, and a method of realizing frequency offset estimation based on the corresponding first reference signal. Optionally, the transmitting end can send multiple reference signals for frequency offset estimation to the receiving end, and perform frequency offset estimation based on the time difference between the multiple reference signals. The following is an introduction:

For example, the reference signal sent by the transmitting end may adopt a sequence with good autocorrelation properties such as an M sequence or a Gold sequence. The reference signal can adopt OOK modulation or ASK modulation. The frequency domain ranges of the multiple reference signals are larger than the frequency domain range of the first channel and include the frequency domain range of the first channel.

Taking the sending end sending two reference signals as an example, in addition to the above-mentioned first reference signal, the sending end can also send a second reference signal to the receiving end. Correspondingly, the receiving end can also receive the second reference signal sent by the sending end. Two reference signals are used for frequency offset estimation.

Correspondingly, the receiving end can determine the frequency offset estimate based on the first reference signal and the second reference signal.

Optionally, the receiving end determines the frequency offset estimate value based on the first reference signal and the second reference signal. The method may be: the receiving end determines a first time difference. The first time difference is when the receiving end receives the first reference signal and when the second reference signal is received. The time difference of the reference signal; the receiving end determines the frequency offset estimate based on the first time difference and the second time difference. The second time difference is the time difference between the sending end sending the first reference signal and the second reference signal.

For example, when the sending end sends at least two reference signals, the receiving end may be notified of the time difference between sending the at least two reference signals. For example, when the sending end sends the first reference signal and the second reference signal to the receiving end, the sending end may also send the second time difference to the receiving end.

Optionally, the transmitting end can send a sequence of at least two reference signals to the receiving end, so that the receiving end can save the sequence locally to facilitate correlation operations with the received reference signals.

After receiving the first reference signal, the receiving end performs down-conversion processing on the received first reference signal, performs filtering processing, performs envelope detection on the filtered signal, and locally saves the envelope signal obtained by the envelope detection. Correlation processing is performed on the corresponding sequence to obtain the time when the first reference signal is received. In the same way, after the receiving end receives the second reference signal, the time at which the second reference signal is received can be obtained. The receiving end can determine the time difference between receiving the first reference signal and receiving the second reference signal based on the clock signal generated in this frame, that is, determining the first time difference. The receiving end may determine the frequency offset estimate based on the first time difference and the above-mentioned second time difference.

Here, the first time difference is the time difference obtained by timing according to the crystal oscillator of the receiving end; and the second time difference is the time difference obtained by timing according to the crystal oscillator of the transmitting end. If both crystal oscillators are relatively accurate, the first time difference can be equal to the second time difference; if there is a difference between the two crystal oscillators, usually the crystal oscillator at the receiving end has a larger deviation, the first time difference will not be equal to the second time difference.

Optional, according to the formula The normalized crystal frequency difference can be calculated, where σ is the normalized crystal frequency difference, T ₂ is the second time difference, and T ₁ is the first time difference. Further, the frequency offset estimate value Δf can be calculated according to Δf = f _c σ, where f _c is the target frequency of down conversion.

For example, FIG. 19 shows a schematic diagram in which the transmitting end sends a first reference signal and a second reference signal to the receiving end, that is, two reference signals are sent. Assume that the two reference signals adopt OOK modulation, and both reference signals modulate the sequence "1010". It should be understood that this is only an example and does not limit the present application.

Before sending two reference signals, the transmitting end notifies the receiving end of the time difference between sending the reference signals twice. In the example shown in Figure 19, the two reference signals are separated by a length of 36 OFDM symbols. In addition, the sending end notifies the receiving end that the sequence of sending the reference signal twice is "1010".

After receiving the signal, the receiving end performs down-conversion processing, filtering processing, and envelope detection of the filtered signal. After that, the receiving end will search for the sequence 1010 in the envelope signal. For example, the receiving end will generally use a local correlator. To perform a sliding correlation operation to find the sequence 1010 in the envelope signal. When the receiver finds the two reference signals, it can determine the time it was received and calculate the time difference between the two. Since the local time is calculated using the clock signal generated by the local oscillator, if there is a frequency drift in the local oscillator, the time difference calculated locally and the time difference notified by the transmitter will be different. For example, the transmitting end notifies that the time difference between two reference signals is 36 OFDM symbols, but the receiving end calculates that the time difference is 37 OFDM symbols. This means that the frequency of the receiving end's crystal oscillator is higher than the transmitting end's crystal oscillator frequency, and its normalized crystal oscillator The frequency difference can be (37-36)/36. In this way, the receiving end can calculate the frequency offset of the local crystal oscillator.

Through the above method, the receiving end can determine the frequency offset estimate, and then compensate the frequency of the local carrier signal at the receiving end to reduce or eliminate the frequency offset.

As a possible example, in order to make frequency offset estimation more accurate, the receiving end can implement signal reception and frequency offset estimation based on the receiver shown in Figure 20 . Among them, two intermediate frequency filters can be set, such as BPF1 and BPF2 in Figure 20. The frequency ranges of BPF1 and BPF2 are different. Optionally, the frequency range of BPF1 is smaller than the frequency range of BPF2. BPF1 is used to receive reference signals (such as receiving the above-mentioned first reference signal). BPF2 is used to receive the signal of the first channel. Among them, the output of the envelope detection module is used for frequency offset estimation, and the carrier signal of the local crystal oscillator is adjusted through the result of the frequency offset estimation module to compensate for the existing frequency offset. In this way, the reference signal is received through the IF filter with a smaller frequency range, which can prevent the IF filter from receiving other interference signals and improve the accuracy of frequency offset estimation.

Based on the above embodiments, embodiments of the present application also provide a communication device. Referring to FIG. 21 , the communication device 2100 may include a transceiver unit 2101 and a processing unit 2102. Among them, the transceiver unit 2101 is used for the communication device 2100 to receive information (signal, message or data) or send information (signal, message or data), and the processing unit 2102 is used to perform actions of the communication device 2100 Control management. The processing unit 2102 can also control the steps performed by the transceiver unit 2101.

Illustratively, the communication device 2100 may be the receiving end in the above embodiment, a processor in the receiving end, or a chip, or a chip system, or a functional module, etc.; or, the communication device 2100 may be specifically It is the sending end in the above embodiment, the processor of the sending end, or a chip, or a chip system, or a functional module, etc.

In one embodiment, when the communication device 2100 is used to implement the functions of the receiving end in the embodiment shown in FIG. 8, it may specifically include: the transceiving unit 2101 may be used to receive the first reference signal sent by the transmitting end. The first reference signal is used for frequency offset estimation. The frequency domain range of the first reference signal is greater than the frequency domain range of the first channel, and the frequency domain range of the first reference signal includes the frequency domain range of the first channel. ; The processing unit 2102 may be configured to determine a frequency offset estimate value based on the first reference signal, and perform frequency offset correction based on the frequency offset estimate value; the transceiver unit 2101 may also be configured to perform frequency offset correction based on the result of the frequency offset correction. The first channel receives the transmitted The signal sent by the sending end.

In an optional implementation, the first reference signal may be a signal whose signal frequency changes linearly with time.

Exemplarily, when determining the frequency offset estimate value according to the first reference signal, the processing unit 2102 is configured to: perform filtering processing on the first reference signal to obtain a filtered reference signal; The filtered reference signal is subjected to envelope detection to obtain a first envelope signal; the frequency offset estimate is determined based on the time difference between the amplitude peaks of the first envelope signal.

Optionally, when the processing unit 2102 determines the frequency offset estimate based on the time difference between the amplitude peaks of the first envelope signal, it is configured to: based on the time difference between the amplitude peaks of the first envelope signal The time difference between, the transmission duration of the first reference signal, the lowest frequency of the first reference signal and the slope of the first reference signal are used to determine the first frequency, and the first frequency is the frequency with frequency offset; The frequency offset estimate is determined based on the first frequency and the second frequency, and the second frequency is a frequency without frequency offset.

In another optional implementation, the first reference signal may be at least one OOK modulated sequence carried on at least one subband, and each subband of the at least one subband includes at least one subcarrier. , each of the at least one subband carries at least one OOK modulated sequence.

Exemplarily, when determining the frequency offset estimate value according to the first reference signal, the processing unit 2102 is configured to: perform filtering processing on the first reference signal to obtain a filtered reference signal; Perform envelope detection on the filtered reference signal to obtain a second envelope signal; demodulate the second envelope signal to obtain a demodulated signal; determine the first subband corresponding to the demodulated signal; according to The first subband and the second subband determine the frequency offset estimate, the second subband is a subband without frequency offset, and the at least one subband includes the second subband.

In an example, the transceiver unit 2101 may also be configured to receive a second reference signal sent by the transmitter, and the second reference signal is used for frequency offset estimation; further, the processing unit 2102 performs the processing according to the When the first reference signal determines the frequency offset estimate value, it is used to: determine the frequency offset estimate value according to the first reference signal and the second reference signal.

Optionally, when determining the frequency offset estimate based on the first reference signal and the second reference signal, the processing unit 2102 is configured to: determine a first time difference, where the first time difference is the Unit 2101 receives the time difference between the first reference signal and the second reference signal; determines the frequency offset estimate value according to the first time difference and the second time difference, and the second time difference is the sending The time difference between the terminal sending the first reference signal and sending the second reference signal.

In a possible way, the transceiver unit 2101 may also be configured to receive the second time difference sent by the sending end.

In another embodiment, when the communication device 2100 is used to implement the functions of the sending end in the embodiment shown in FIG. 8, it may specifically include: the transceiving unit 2101 may be used to send the first reference signal to the receiving end. The first reference signal is used for frequency offset estimation; the frequency domain range of the first reference signal is greater than the frequency domain range of the first channel, and the frequency domain range of the first reference signal includes the frequency domain range of the first channel ; And, send a signal to the receiving end on the first channel; the processing unit 2102 can be used to control the transceiver unit 2101 to perform a transceiver operation.

In another optional implementation, the first reference signal may be at least one switch-keyed OOK modulated sequence carried on at least one subband, and each subband in the at least one subband includes at least one Subcarriers, each of the at least one subband carries an OOK modulated sequence.

Exemplarily, the transceiver unit 2101 may also be configured to send a second reference signal to the receiving end, where the second reference signal is used for frequency offset estimation.

Optionally, the transceiver unit 2101 may also be configured to send a second time difference to the receiving end, where the second time difference is the time difference between sending the first reference signal and sending the second reference signal.

It should be noted that the division of units in the embodiment of the present application is schematic and is only a logical function division. In actual implementation, there may be other division methods. Each functional unit in the embodiment of the present application can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated units can be implemented in the form of hardware or software functional units.

If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or contributes to the existing technology, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium , including several instructions to cause a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the methods described in various embodiments of the application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), Various media such as magnetic disks or optical disks that can store program code.

Based on the above embodiments, embodiments of the present application also provide a communication device. Referring to FIG. 22 , the communication device 2200 may include a transceiver 2201 and a processor 2202 . Optionally, the communication device 2200 may also include a memory 2203. The memory 2203 may be disposed inside the communication device 2200 or may be disposed outside the communication device 2200 . Wherein, the processor 2202 can control the transceiver 2201 to receive and send signals, information, messages or data, etc.

Specifically, the processor 2202 may be a central processing unit (CPU), a network processor (NP) or a combination of CPU and NP. The processor 2202 may further include a hardware chip. The above-mentioned hardware chip can be an application-specific integrated circuit (ASIC), a programmable logic device (PLD) or a combination thereof. The above-mentioned PLD can be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a general array logic (GAL) or any combination thereof.

The transceiver 2201, the processor 2202 and the memory 2203 are connected to each other. Optionally, the transceiver 2201, the processor 2202 and the memory 2203 are connected to each other through a bus 2204; the bus 2204 can be a peripheral component interconnect standard (Peripheral Component Interconnect, PCI) bus or an extended industry standard. Structure (Extended Industry Standard Architecture, EISA) bus, etc. The bus can be divided into address bus, data bus, control bus, etc. For ease of presentation, only one thick line is used in Figure 22, but it does not mean that there is only one bus or one type of bus.

In an optional implementation, the memory 2203 is used to store programs, etc. Specifically, the program may include program code including computer operating instructions. The memory 2203 may include RAM, and may also include non-volatile memory (non-volatile memory), such as one or more disk memories. The processor 2202 executes the application program stored in the memory 2203 to implement the above functions, thereby realizing the functions of the communication device 2200 .

For example, the communication device 2200 may be the network device in the above embodiment; it may also be the first terminal device in the above embodiment.

In one embodiment, when the communication device 2200 implements the functions of the receiving end in the embodiment shown in Figure 8, the transceiver 2201 can implement the sending and receiving operations performed by the receiving end in the embodiment shown in Figure 8; processor 2202 can implement other operations other than the sending and receiving operations performed by the receiving end in the embodiment shown in FIG. 8 . For specific relevant descriptions, please refer to the relevant descriptions in the embodiment shown in FIG. 8 , and will not be introduced in detail here. Optionally, the transceiver 2201 may include a receiver as shown in Figure 18.

In another embodiment, when the communication device 2200 implements the functions of the sending end in the embodiment shown in Figure 8, the transceiver 2201 can implement the sending and receiving operations performed by the sending end in the embodiment shown in Figure 8; Processing The processor 2202 may implement other operations other than the sending and receiving operations performed by the sending end in the embodiment shown in FIG. 8 . For specific relevant descriptions, please refer to the relevant descriptions in the embodiment shown in FIG. 8 , and will not be introduced in detail here.

Based on the above embodiments, embodiments of the present application provide a communication system, which may include the sending end and receiving end involved in the above embodiments.

Embodiments of the present application also provide a computer-readable storage medium. The computer-readable storage medium is used to store a computer program. When the computer program is executed by a computer, the computer can implement the communication method provided by the above method embodiment.

Embodiments of the present application also provide a computer program product. The computer program product is used to store a computer program. When the computer program is executed by a computer, the computer can implement the communication method provided by the above method embodiment.

An embodiment of the present application also provides a chip, including a processor, which is coupled to a memory and configured to call a program in the memory so that the chip implements the communication method provided by the above method embodiment.

An embodiment of the present application also provides a chip, which is coupled to a memory, and is used to implement the communication method provided by the above method embodiment.

Those skilled in the art will understand that embodiments of the present application may be provided as methods, systems, or computer program products. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment that combines software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to the present application. It will be understood that each process and/or block in the flowchart illustrations and/or block diagrams, and combinations of processes and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to produce a machine that operates by the computer or other programmable data processing device. The instructions executed by the processor produce means for implementing the functions specified in the process or processes of the flow diagram and/or the block or blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory that causes a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction means, the instructions The device implements the functions specified in a process or processes of the flowchart and/or a block or blocks of the block diagram.

These computer program instructions may also be loaded onto a computer or other programmable data processing device, causing a series of operating steps to be performed on the computer or other programmable device to produce computer-implemented processing, thereby executing on the computer or other programmable device. Instructions provide steps for implementing the functions specified in a process or processes of a flowchart diagram and/or a block or blocks of a block diagram.

Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the scope of the present application. In this way, if these modifications and variations of the present application fall within the scope of the claims of the present application and equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

A communication method, characterized by including:

The receiving end receives a first reference signal sent by the transmitting end, the first reference signal is used for frequency offset estimation, the frequency domain range of the first reference signal is greater than the frequency domain range of the first channel, and the first reference signal The frequency domain range includes the frequency domain range of the first channel;

The receiving end determines a frequency offset estimate based on the first reference signal;

The receiving end performs frequency offset correction according to the frequency offset estimate;

The receiving end receives the signal sent by the transmitting end on the first channel based on the frequency offset correction result.
The method of claim 1, wherein the first reference signal is a signal whose signal frequency changes linearly with time.
The method of claim 1 or 2, wherein the receiving end determines the frequency offset estimate based on the first reference signal, including:

The receiving end performs filtering processing on the first reference signal to obtain a filtered reference signal;

The receiving end performs envelope detection on the filtered reference signal to obtain a first envelope signal;

The receiving end determines the frequency offset estimate based on the time difference between amplitude peaks of the first envelope signal.
The method of claim 3, wherein the receiving end determines the frequency offset estimate based on the time difference between amplitude peaks of the first envelope signal, including:

The receiving end determines based on the time difference between the amplitude peaks of the first envelope signal, the transmission duration of the first reference signal, the lowest frequency of the first reference signal and the slope of the first reference signal. A first frequency, the first frequency is a frequency with frequency offset;

The receiving end determines the frequency offset estimate based on the first frequency and a second frequency, and the second frequency is a frequency without frequency offset.
The method of claim 1, wherein the first reference signal is a sequence of at least one switch-keyed OOK modulation carried on at least one subband, and each subband in the at least one subband includes At least one subcarrier, each of the at least one subband carrying at least one OOK modulated sequence.
The method of claim 5, wherein the receiving end determines the frequency offset estimate based on the first reference signal, including:

The receiving end performs filtering processing on the first reference signal to obtain a filtered reference signal;

The receiving end performs envelope detection on the filtered reference signal to obtain a second envelope signal;

The receiving end demodulates the second envelope signal to obtain a demodulated signal;

The receiving end determines the first subband corresponding to the demodulated signal;

The receiving end determines the frequency offset estimate value according to the first subband and the second subband, the second subband is a subband without frequency offset, and the at least one subband includes the second subband. Subband.
The method of claim 1, characterized in that:

The method also includes:

The receiving end receives a second reference signal sent by the transmitting end, and the second reference signal is used for frequency offset estimation;

The receiving end determines the frequency offset estimate based on the first reference signal, including:

The receiving end determines the frequency offset estimate based on the first reference signal and the second reference signal.
The method of claim 7, wherein the receiving end determines the frequency offset estimate based on the first reference signal and the second reference signal, including:

The receiving end determines a first time difference, where the first time difference is the time difference between when the receiving end receives the first reference signal and when the receiving end receives the second reference signal;

The receiving end determines the frequency offset estimate based on the first time difference and the second time difference. The second time difference is the time difference between the sending end sending the first reference signal and the second reference signal. .
The method of claim 8, further comprising:

The receiving end receives the second time difference sent by the sending end.
A communication method, characterized by including:

The transmitting end sends a first reference signal to the receiving end, the first reference signal is used for frequency offset estimation; the frequency domain range of the first reference signal is greater than the frequency domain range of the first channel, and the first reference signal has The frequency domain range includes the frequency domain range of the first channel;

The sending end sends a signal to the receiving end on the first channel.
The method of claim 10, wherein the first reference signal is a signal whose signal frequency changes linearly with time.
The method of claim 10, wherein the first reference signal is a sequence of at least one switch-keyed OOK modulation carried on at least one subband, and each subband in the at least one subband includes At least one subcarrier, each of the at least one subband carrying at least one OOK modulated sequence.
The method of claim 10, further comprising:

The transmitting end sends a second reference signal to the receiving end, and the second reference signal is used for frequency offset estimation.
The method of claim 13, further comprising:

The sending end sends a second time difference to the receiving end, where the second time difference is the time difference between when the sending end sends the first reference signal and the second reference signal.
A communication device, characterized by including:

A transceiver unit configured to receive a first reference signal sent by the transmitting end. The first reference signal is used for frequency offset estimation. The frequency domain range of the first reference signal is greater than the frequency domain range of the first channel, and the first reference signal is used for frequency offset estimation. The frequency domain range of a reference signal includes the frequency domain range of the first channel;

A processing unit configured to determine a frequency offset estimate based on the first reference signal, and perform frequency offset correction based on the frequency offset estimate;

The transceiver unit is further configured to receive the signal sent by the transmitting end on the first channel based on the result of frequency offset correction.
The device of claim 15, wherein the first reference signal is a signal whose signal frequency changes linearly with time.
The device of claim 15 or 16, wherein the processing unit, when determining the frequency offset estimate based on the first reference signal, is configured to:

Perform filtering processing on the first reference signal to obtain a filtered reference signal;

Perform envelope detection on the filtered reference signal to obtain a first envelope signal;

The frequency offset estimate is determined based on the time difference between amplitude peaks of the first envelope signal.
The device of claim 17, wherein the processing unit, when determining the frequency offset estimate based on the time difference between amplitude peaks of the first envelope signal, is configured to:

Determine the first frequency according to the time difference between the amplitude peaks of the first envelope signal, the transmission duration of the first reference signal, the lowest frequency of the first reference signal and the slope of the first reference signal, The first frequency is a frequency with frequency offset;

The frequency offset estimate is determined based on the first frequency and the second frequency, and the second frequency is a frequency without frequency offset.
The apparatus of claim 15, wherein the first reference signal is a sequence of at least one switch-keyed OOK modulation carried on at least one subband, and each subband in the at least one subband includes At least one subcarrier, each of the at least one subband carrying at least one OOK modulated sequence.
The device of claim 19, wherein when the processing unit determines the frequency offset estimate based on the first reference signal, it is configured to:

Perform filtering processing on the first reference signal to obtain a filtered reference signal;

Perform envelope detection on the filtered reference signal to obtain a second envelope signal;

Demodulate the second envelope signal to obtain a demodulated signal;

Determine the first subband corresponding to the demodulated signal;

The frequency offset estimate value is determined according to the first subband and the second subband, the second subband is a subband without frequency offset, and the at least one subband includes the second subband.
The device according to claim 15, characterized in that:

The transceiver unit is also used for:

Receive a second reference signal sent by the transmitting end, where the second reference signal is used for frequency offset estimation;

When determining the frequency offset estimate based on the first reference signal, the processing unit is configured to:

The frequency offset estimate is determined based on the first reference signal and the second reference signal.
The device of claim 21, wherein when determining the frequency offset estimate based on the first reference signal and the second reference signal, the processing unit is configured to:

Determine a first time difference, where the first time difference is the time difference between when the transceiver unit receives the first reference signal and when the second reference signal is received;

The frequency offset estimate value is determined according to the first time difference and the second time difference, and the second time difference is the time difference between the sending end sending the first reference signal and the second reference signal.
The device according to claim 22, characterized in that the transceiver unit is also used for:

Receive the second time difference sent by the sending end.
A communication device, characterized by including:

A transceiver unit configured to send a first reference signal to the receiving end, where the first reference signal is used for frequency offset estimation; the frequency domain range of the first reference signal is greater than the frequency domain range of the first channel, and the first reference signal is used for frequency offset estimation. The frequency domain range of the reference signal includes the frequency domain range of the first channel; and

Send a signal to the receiving end on the first channel;

A processing unit, used to control the transceiver unit to perform transceiver operations.
The device of claim 24, wherein the first reference signal is a signal whose signal frequency changes linearly with time.
The apparatus of claim 24, wherein the first reference signal is a sequence of at least one switch-keyed OOK modulation carried on at least one subband, and each subband in the at least one subband includes At least one subcarrier, each of the at least one subband carrying at least one OOK modulated sequence.
The device according to claim 24, characterized in that the transceiver unit is also used for:

A second reference signal is sent to the receiving end, where the second reference signal is used for frequency offset estimation.
The device according to claim 27, characterized in that the transceiver unit is also used for:

Send a second time difference to the receiving end, where the second time difference is the time difference between sending the first reference signal and sending the second reference signal.
A communication device, characterized by including a memory, a processor and a transceiver, wherein:

The memory is used to store computer instructions;

The transceiver is used to receive and transmit signals;

The processor is coupled to the memory and configured to invoke computer instructions in the memory to perform the method according to any one of claims 1-9 through the transceiver.
A communication device, characterized by including a memory, a processor and a transceiver, wherein:

The memory is used to store computer instructions;

The transceiver is used to receive and transmit signals;

The processor is coupled to the memory and configured to invoke computer instructions in the memory to perform the method of any one of claims 10-14 through the transceiver.
A computer-readable storage medium, characterized in that computer-executable instructions are stored in the computer-readable storage medium, and when called by the computer, the computer-executable instructions execute any of claims 1-9. A method according to one of the preceding claims, or a method according to any one of claims 10-14.
A computer program product, characterized in that it contains instructions that, when run on a computer, cause the method as claimed in any one of claims 1 to 9, or the method as claimed in any one of claims 10 to 14 The method described is executed.
A chip, characterized in that the chip is coupled to a memory and is used to read and execute program instructions stored in the memory to implement the method as described in any one of claims 1-9, or to implement as The method described in any one of claims 10-14.