CN111245750B

CN111245750B - Frequency offset estimation method, device and storage medium

Info

Publication number: CN111245750B
Application number: CN202010018939.6A
Authority: CN
Inventors: 杨恩浩; 谭舒; 杨柳飞; 林登彪
Original assignee: Unisoc Chongqing Technology Co Ltd
Current assignee: Unisoc Chongqing Technology Co Ltd
Priority date: 2020-01-08
Filing date: 2020-01-08
Publication date: 2023-03-31
Anticipated expiration: 2040-01-08
Also published as: CN111245750A

Abstract

The present disclosure relates to the field of communications technologies, and in particular, to a frequency offset estimation method, apparatus, and storage medium. The method comprises the following steps: acquiring a local PBCH signal, wherein the local PBCH signal comprises a local PBCH signal corresponding to each of a plurality of reconstructed estimation samples; acquiring a frequency domain received PBCH signal, wherein the frequency domain received PBCH signal comprises frequency domain received PBCH signals corresponding to the received multiple estimation samples respectively; and carrying out frequency offset estimation according to the local PBCH signal and the frequency domain received PBCH signal to obtain a frequency offset estimation result. According to the embodiment of the disclosure, the local PBCH signal and the frequency domain receiving PBCH signal are used as the statistical samples of PBCH frequency offset estimation, so that the coverage area of the scheme is increased in a mode of increasing the number of samples, the precision of the frequency offset estimation is improved, and the PBCH frequency offset estimation performance under the low signal-to-noise ratio is effectively improved.

Description

Frequency offset estimation method, device and storage medium

Technical Field

The present disclosure relates to the field of communications technologies, and in particular, to a frequency offset estimation method, apparatus, and storage medium.

Background

In a communication system, due to the influence of various factors, frequency deviation exists between user equipment and access network equipment, which is reflected in that a received signal carries frequency deviation interference, the frequency deviation interference does not influence the analysis of the received signal, and the operation state of the whole user equipment is paralyzed in severe cases, so that the problem of network drop occurs.

Therefore, a targeted frequency offset estimation scheme needs to be designed at the user equipment end to estimate the frequency offset existing between the user equipment and the access network equipment, and then corresponding correction compensation is performed at the user equipment end to ensure the performance of the user equipment. In the related art, frequency offset estimation is usually performed based on several available physical signals (e.g., primary Synchronization Signal (PSS), secondary Synchronization Signal (SSS), or Cell-specific reference Signal (CRS)), and the existing frequency offset estimation schemes are mainly embodied as two types, i.e., maximum likelihood scheme and phase difference scheme.

However, the precision of the above scheme has a large loss at low signal-to-noise ratio, and cannot meet the design requirements of the system.

Disclosure of Invention

In view of the above, the present disclosure provides a frequency offset estimation method, apparatus, and storage medium. The technical scheme is as follows:

according to an aspect of the present disclosure, there is provided a frequency offset estimation method, used in a user equipment, the method including:

acquiring a local Physical Broadcast Channel (PBCH) signal, wherein the local PBCH signal comprises a local PBCH signal corresponding to each of a plurality of reconstructed estimation samples;

acquiring a frequency domain received PBCH signal, wherein the frequency domain received PBCH signal comprises frequency domain received PBCH signals corresponding to the received multiple estimation samples respectively;

and carrying out frequency offset estimation according to the local PBCH signal and the frequency domain received PBCH signal to obtain a frequency offset estimation result.

In a possible implementation manner, the performing, according to the local PBCH signal and the frequency-domain received PBCH signal, frequency offset estimation to obtain a frequency offset estimation result includes:

carrying out frequency coarse estimation according to the local PBCH signal and the frequency domain receiving PBCH signal to obtain a frequency coarse estimation value and a signal quality index;

and determining the frequency offset estimation result according to the frequency rough estimation value and the signal quality index.

In another possible implementation manner, the performing coarse frequency estimation according to the local PBCH signal and the frequency-domain received PBCH signal to obtain a coarse frequency estimation value and a signal quality indicator includes:

determining frequency domain channel impulse responses corresponding to the plurality of estimation samples according to the local PBCH signal and the frequency domain received PBCH signal;

for each estimation sample in the plurality of estimation samples, determining a time domain channel impulse response corresponding to the estimation sample according to a frequency domain channel impulse response corresponding to the estimation sample;

merging the time domain channel impact responses corresponding to the multiple estimation samples to obtain a target superposition result;

and determining the frequency rough estimation value and the signal quality index according to the target superposition result.

In another possible implementation manner, the frequency domain channel impulse response corresponding to the estimation sample includes frequency domain channel impulse responses corresponding to a plurality of frequency domain resource units of the estimation sample, and the time domain channel impulse response corresponding to the estimation sample includes time domain channel impulse responses corresponding to the plurality of frequency domain resource units of the estimation sample;

the merging the time domain channel impulse responses corresponding to the multiple estimation samples to obtain a target superposition result includes:

and performing incoherent superposition on the time domain channel impact responses of the same frequency domain resource units in the plurality of estimation samples to obtain the target superposition result, wherein the target superposition result comprises target time domain channel impact responses corresponding to the plurality of frequency domain resource units.

In another possible implementation manner, the determining, according to the local PBCH signal and the frequency-domain received PBCH signal, frequency-domain channel impulse responses corresponding to the multiple estimation samples includes:

for each of the plurality of estimation samples, determining a frequency domain channel impulse response corresponding to each of a plurality of OFDM symbols of the estimation sample according to the local PBCH signal and the frequency domain received PBCH signal;

for each of the plurality of estimation samples, determining frequency domain channel impulse responses corresponding to the plurality of frequency domain resource units of the estimation sample according to frequency domain channel impulse responses corresponding to a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols of the estimation sample.

In another possible implementation manner, the frequency domain channel impulse responses corresponding to the plurality of OFDM symbols respectively include:

carrying full frequency domain position channel impact response corresponding to the OFDM symbol of the PBCH signal; and/or the full frequency domain position channel impulse response corresponding to the OFDM symbol which does not carry the PBCH signal.

In another possible implementation manner, the determining the coarse frequency estimation value and the signal quality indicator according to the target superposition result includes:

determining the signal quality index according to the maximum value of the multiple target time domain channel impulse responses in the target superposition result;

and determining the frequency coarse estimation value according to a target position number corresponding to the maximum value, wherein the target position number is used for indicating the position of the maximum value in the target superposition result.

In another possible implementation manner, the determining the signal quality indicator according to the maximum value in the target superposition result includes:

and determining the signal quality index SignalQualFactor according to the maximum value in the target superposition result by the following formula:

the maximum value is MaxValue, the NIFFTNum is a preset Inverse Fast Fourier Transform (IFFT) point number, the TH _ POWER [ n ] is the target superposition result, the value range of n is 1-NIFFTNum, and the NIFFTNum is a positive integer greater than 1.

In another possible implementation manner, the determining the coarse frequency estimation value according to the target location number corresponding to the maximum value includes:

when the target position number is less than half of the preset IFFT point number, multiplying the target position number by the preset frequency granularity to obtain the frequency coarse estimation value;

and when the target position number is more than or equal to half of the IFFT points, multiplying a target difference value by the frequency granularity to obtain the coarse frequency estimation value, wherein the target difference value is the difference value between the target position number and the IFFT points.

In another possible implementation manner, the determining, according to the coarse frequency estimation value and the signal quality indicator, the frequency offset estimation result includes:

performing frequency offset fine estimation according to the frequency rough estimation value and the signal quality index to obtain a frequency fine estimation value;

and determining the frequency offset estimation result according to the frequency rough estimation value and the frequency fine estimation value.

In another possible implementation manner, the performing, according to the coarse frequency estimation value and the signal quality indicator, a frequency offset fine estimation to obtain a fine frequency estimation value includes:

when the signal quality index is higher than a quality index threshold value, carrying out frequency offset correction on the frequency domain channel impact response according to the frequency rough estimation value to obtain frequency domain channel impact response after frequency offset correction;

and performing frequency offset fine estimation according to the frequency domain channel impact response after the frequency offset correction to obtain the frequency fine estimation value.

when the signal quality index is lower than or equal to a quality index threshold value, determining a noise area in the target superposition result according to the target position number corresponding to the maximum value;

performing zero setting processing on a plurality of target time domain channel impulse responses included in the noise region in the target superposition result to obtain a time domain channel impulse response after the zero setting processing;

performing Fast Fourier Transform (FFT) operation on the time domain channel impulse response subjected to the zero setting processing to obtain an operated frequency domain channel impulse response;

performing frequency offset correction on the operated frequency domain channel impact response according to the rough frequency offset estimation value to obtain the frequency domain channel impact response after the frequency offset correction;

In another possible implementation manner, the determining the frequency offset estimation result according to the coarse frequency estimation value and the fine frequency estimation value includes:

and determining the sum of the frequency rough estimation value and the frequency fine estimation value as the frequency offset estimation result.

In another possible implementation manner, the acquiring the local PBCH signal includes:

after a service cell is successfully resided, acquiring MIB information of a main system information block corresponding to the service cell;

and reconstructing to obtain the local PBCH signal according to the MIB information.

In another possible implementation manner, the acquiring the frequency domain received PBCH signal includes:

receiving time domain receiving data carrying PBCH signals, wherein the time domain receiving data is data of the multiple estimation samples in the time domain;

and performing time-frequency conversion on the time domain receiving data to obtain the frequency domain receiving PBCH signal.

According to another aspect of the present disclosure, there is provided a frequency offset estimation apparatus, for use in a user equipment, the apparatus including:

a first obtaining module, configured to obtain a local PBCH signal, where the local PBCH signal includes a local PBCH signal corresponding to each of a plurality of reconstructed estimation samples;

a second obtaining module, configured to obtain a frequency-domain received PBCH signal, where the frequency-domain received PBCH signal includes frequency-domain received PBCH signals corresponding to the received multiple estimation samples, respectively;

and the estimation module is used for carrying out frequency offset estimation according to the local PBCH signal and the frequency domain receiving PBCH signal to obtain a frequency offset estimation result.

In a possible implementation manner, the estimation module is further configured to:

In another possible implementation manner, the estimation module is further configured to

In another possible implementation manner, the frequency domain channel impulse response corresponding to the estimation sample includes frequency domain channel impulse responses corresponding to respective multiple frequency domain resource units of the estimation sample, and the time domain channel impulse response corresponding to the estimation sample includes time domain channel impulse responses corresponding to respective multiple frequency domain resource units of the estimation sample;

the estimation module is further configured to perform incoherent superposition on the time domain channel impulse responses of the same frequency domain resource units in the multiple estimation samples to obtain the target superposition result, where the target superposition result includes target time domain channel impulse responses corresponding to the multiple frequency domain resource units.

In another possible implementation manner, the estimating module is further configured to determine, for each of the plurality of estimation samples, a frequency-domain channel impulse response corresponding to each of a plurality of OFDM symbols of the estimation sample according to the local PBCH signal and the frequency-domain received PBCH signal;

In another possible implementation manner, the estimation module is further configured to determine the signal quality indicator according to a maximum value of multiple target time domain channel impulse responses in the target superposition result; and determining the frequency coarse estimation value according to a target position number corresponding to the maximum value, wherein the target position number is used for indicating the position of the maximum value in the target superposition result.

In another possible implementation manner, the estimation module is further configured to determine, according to a maximum value in the target superposition result, the signal quality indicator SignalQualFactor by using the following formula:

In another possible implementation manner, the estimation module is further configured to:

when the target position number is less than half of the number of the preset IFFT points, multiplying the target position number by the preset frequency granularity to obtain the frequency rough estimation value;

In another possible implementation manner, the estimation module is further configured to, when the signal quality indicator is higher than a quality indicator threshold, perform frequency offset correction on the frequency domain channel impulse response according to the coarse frequency estimation value, to obtain a frequency domain channel impulse response after the frequency offset correction; and performing frequency offset fine estimation according to the frequency domain channel impact response after the frequency offset correction to obtain the frequency fine estimation value.

performing zero setting processing on a plurality of target time domain channel impact responses included in the noise region in the target superposition result to obtain time domain channel impact responses after the zero setting processing;

In another possible implementation manner, the first obtaining module is further configured to obtain, after the serving cell is successfully camped, information of a main system information block MIB corresponding to the serving cell; and reconstructing to obtain the local PBCH signal according to the MIB information.

In another possible implementation manner, the second obtaining module is configured to receive time-domain received data carrying a PBCH signal, where the time-domain received data is data of the multiple estimation samples in a time domain; and performing time-frequency conversion on the time domain receiving data to obtain the frequency domain receiving PBCH signal.

According to another aspect of the present disclosure, there is provided a user equipment including: a processor; a memory for storing processor-executable instructions;

wherein the processor is configured to:

acquiring a local PBCH signal, wherein the local PBCH signal comprises a local PBCH signal corresponding to each of a plurality of reconstructed estimation samples;

According to another aspect of the present disclosure, there is provided a non-transitory computer readable storage medium having stored thereon computer program instructions which, when executed by a processor, implement the above-described method.

The method includes the steps that a user device obtains a local PBCH signal and a frequency domain receiving PBCH signal, frequency offset estimation is carried out according to the local PBCH signal and the frequency domain receiving PBCH signal, and a frequency offset estimation result is obtained, wherein the local PBCH signal comprises the local PBCH signal corresponding to a plurality of estimation samples obtained through reconstruction, and the frequency domain receiving PBCH signal comprises the frequency domain receiving PBCH signal corresponding to the plurality of received estimation samples; the user equipment takes the local PBCH signal obtained by reconstruction and the received frequency domain receiving PBCH signal as the statistic sample of PBCH frequency offset estimation, the coverage range of the scheme is increased by increasing the number of samples, the precision of the frequency offset estimation is improved, and the PBCH frequency offset estimation performance under low signal-to-noise ratio is effectively improved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments, features, and aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.

Fig. 1 is a schematic structural diagram of a mobile communication system provided in an exemplary embodiment of the present disclosure;

fig. 2 shows a flowchart of a frequency offset estimation method provided by an exemplary embodiment of the present disclosure;

fig. 3 shows a flow chart of a frequency offset estimation method provided by another exemplary embodiment of the present disclosure;

fig. 4 shows a flowchart of a frequency offset estimation method provided by another exemplary embodiment of the present disclosure;

fig. 5 is a schematic diagram illustrating a frequency offset estimation method according to another exemplary embodiment of the present disclosure;

fig. 6 is a schematic diagram illustrating a frequency offset estimation method according to another exemplary embodiment of the present disclosure;

fig. 7 is a schematic diagram illustrating a frequency offset estimation method according to another exemplary embodiment of the present disclosure;

fig. 8 shows a flowchart of a frequency offset estimation method provided by another exemplary embodiment of the present disclosure;

fig. 9 is a schematic diagram illustrating a structure of a frequency offset estimation apparatus according to an exemplary embodiment of the present disclosure;

fig. 10 shows a schematic structural diagram of a user equipment provided in an exemplary embodiment of the present disclosure.

Detailed Description

Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present disclosure. It will be understood by those skilled in the art that the present disclosure may be practiced without some of these specific details. In some instances, methods, means, elements and circuits that are well known to those skilled in the art have not been described in detail so as not to obscure the present disclosure.

Along with the increasingly obvious differentiation of the application requirements of consumers, the application scenes of the mobile terminal are increasingly differentiated, and it is difficult to have a technical mode which can represent the optimal compromise between the capability and the efficiency under various application scenes. Therefore, for different application scene requirements, mobile communication evolves three major scenes and application technologies thereof: enhanced Mobile Broadband (eMBB), massive Machine Type Communication (mMTC), and Ultra Reliable Low Latency Communications (uRLLC). The mMTC and the eMTC are application scenes of the Internet of things, and the two most remarkable characteristics of the application scenes are coverage enhancement and low power consumption, which bring great challenges to traditional frequency offset estimation schemes in the related technology (1) the coverage capability needs to reach sinr = -15db or below, but the traditional frequency offset estimation scheme is difficult to work under the signal quality, which is reflected in that the estimation variance is large and the performance is difficult to meet; (2) In order to reduce power consumption, the system has longer sleep time, and compared with a short sleep mode, the system brings larger initial frequency offset when being awakened each time, and the traditional frequency offset estimation scheme brings great challenges.

Therefore, the embodiment of the disclosure provides a frequency offset estimation method, a frequency offset estimation device and a storage medium. According to the method and the device, the local PBCH signal obtained through reconstruction and the received frequency domain receiving PBCH signal are used as the statistical sample of PBCH frequency offset estimation, so that the coverage range of the scheme is increased in a mode of increasing the number of samples, the accuracy of frequency offset estimation is improved, and the performance of PBCH frequency offset estimation under a low signal-to-noise ratio is effectively improved.

Referring to fig. 1, a schematic structural diagram of a mobile communication system according to an exemplary embodiment of the present disclosure is shown. The mobile communication system may be a Long Term Evolution (LTE) system, or may be a 5G system, where the 5G system is also called a New Radio (NR) system, or may be a next generation mobile communication technology system of 5G, and this embodiment is not limited thereto.

Optionally, the mobile communication system is applicable to different network architectures, including but not limited to a relay network architecture, a dual link architecture, a Vehicle to evolution (V2X) architecture, and the like.

The mobile communication system includes: a network side device 120 and a user device 140.

The Network side device 120 may be a Base Station (BS), which may also be referred to as a base station device, and is a device deployed in a Radio Access Network (RAN) to provide a wireless communication function. For example, the device providing the base station function in the 2G network includes a Base Transceiver Station (BTS), the device providing the base station function in the 3G network includes a node B (english: nodeB), the device providing the base station function in the 4G network includes an evolved node B (evolved NodeB, eNB), the device providing the base station function in the Wireless Local Area Network (WLAN) is an Access Point (AP), the device providing the base station function in the 5G system is a gNB, and the evolved node B (english: ng-eNB), the network side device 120 in the embodiment of the present disclosure further includes a device providing the base station function in a new communication system in the future, and the specific implementation manner of the network side device 120 in the embodiment of the present disclosure is not limited. The access network equipment may also include Home base stations (Home enbs, henbs), relays (Relay), pico base stations Pico, etc.

The base station controller is a device for managing a base station, such as a Base Station Controller (BSC) in a 2G network, a Radio Network Controller (RNC) in a 3G network, and a device for controlling and managing a base station in a future new communication system.

The network side device 120 includes a base station of a radio access network, and may further include a base station controller of the radio access network, and may further include a device on the core network side.

The Core Network may be an Evolved Packet Core (EPC), a 5G Core Network (english: 5G Core Network), or a new Core Network in a future communication system. The 5G Core Network is composed of a set of devices, and implements Access and Mobility Management functions (AMF) of functions such as Mobility Management, user Plane Functions (UPF) providing functions such as packet routing forwarding and Quality of Service (QoS) Management, session Management Functions (SMF) providing functions such as Session Management, IP address allocation and Management, and the like. The EPC may be composed of an MME providing functions such as mobility management, gateway selection, etc., a Serving Gateway (S-GW) providing functions such as packet forwarding, etc., and a PDN Gateway (P-GW) providing functions such as terminal address allocation, rate control, etc.

The network side device 120 and the user equipment 140 establish a wireless connection over a wireless air interface. Optionally, the wireless air interface is a wireless air interface based on a 5G standard, for example, the wireless air interface is NR; or, the wireless air interface may also be a wireless air interface based on a 5G next generation mobile communication network technology standard; alternatively, the radio air interface may be a radio air interface based on a 4G standard (LTE system). The network side device 120 may receive the uplink data sent by the user equipment 140 through the wireless connection.

The user equipment 140 may refer to a device in data communication with the network-side device 120. The user equipment 140 may communicate with one or more core networks via a radio access network. The user equipment 140 may be various forms of user equipment, access terminal equipment, subscriber unit, subscriber station, mobile Station (MS), remote station, remote terminal equipment, mobile device, terminal equipment (terminal equipment), wireless communication device, user agent, or user device. The user equipment 140 may also be a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device with Wireless communication function, a computing device or other processing device connected to a Wireless modem, a vehicle-mounted device, a wearable device, a terminal device in a future 5G Network or a terminal device in a future evolved Public Land Mobile Network (PLMN), and the like, which is not limited in this embodiment. The user equipment 140 may receive the downlink data sent by the network side device 120 through a wireless connection with the network side device 120.

It should be noted that, when the mobile communication system shown in fig. 1 adopts a 5G system or a 5G next generation mobile communication technology system, the above network elements may have different names in the 5G system or the 5G next generation mobile communication technology system, but have the same or similar functions, and the embodiment of the present disclosure is not limited thereto.

It should be noted that, in the mobile communication system shown in fig. 1, a plurality of network-side devices 120 and/or a plurality of user devices 140 may be included, and one network-side device 120 and one user device 140 are illustrated in fig. 1, but the embodiment of the present disclosure does not limit this.

Several exemplary embodiments are described below to describe the frequency offset estimation method provided by the embodiments of the present disclosure.

Referring to fig. 2, a flowchart of a method for estimating a frequency offset according to an exemplary embodiment of the present disclosure is shown, which is illustrated in the embodiment that the method is used in the user equipment 140 shown in fig. 1. The method comprises the following steps.

Step 201, a local PBCH signal is obtained, where the local PBCH signal includes a local PBCH signal corresponding to each of the multiple reconstructed estimation samples.

And the user equipment acquires the reconstructed local PBCH signal, wherein the local PBCH signal comprises the local PBCH signal corresponding to each of the plurality of reconstructed estimation samples.

After the user equipment successfully resides in the service cell, acquiring Information of a main system Information Block (MIB) corresponding to the service cell; and reconstructing to obtain a local PBCH signal according to the MIB information.

Since the MIB information corresponding to the serving cell is known to the user equipment after the serving cell successfully resides in the serving cell, the data transmission flow of the transmitter can be simulated based on the MIB information, and the PBCH signal to be received by the local PBCH is reconstructed to re-encode back to the theoretical local PBCH signal to be transmitted, so as to obtain the local PBCH signal corresponding to each of the multiple estimation samples.

Optionally, the estimated samples are a plurality of designated subframes. The local PBCH signal comprises a local PBCH signal corresponding to each of a plurality of reconstructed designated subframes. Each designated subframe includes a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols, and the local PBCH signal corresponding to each designated subframe includes a local PBCH signal corresponding to each of the plurality of OFDM symbols.

Wherein, in a Frequency Division Duplexing (FDD) mode, the designated subframes include subframe 0 and/or subframe 9; in a Time Division Duplex (TDD) mode, a subframe is specified to include subframe 0 and/or subframe 5. This embodiment does not limit this.

Step 202, obtaining a frequency domain received PBCH signal, where the frequency domain received PBCH signal includes frequency domain received PBCH signals corresponding to the received multiple estimation samples.

The user equipment acquires the received frequency domain receiving PBCH signal. Wherein the frequency domain receiving PBCH signal is a PBCH signal received in the frequency domain.

The method comprises the steps that user equipment receives time domain receiving data carrying PBCH signals, wherein the time domain receiving data are data of a plurality of estimation samples in a time domain; and performing time-frequency conversion on the time domain receiving data to obtain a frequency domain receiving PBCH signal.

Optionally, the time-frequency converting, by the ue, the time-domain received data to obtain a frequency-domain received PBCH signal includes: the user equipment performs Fast Fourier Transform (FFT) on the time-domain received data to obtain a frequency-domain received PBCH signal.

Optionally, the estimated samples are a plurality of designated subframes. The frequency domain reception of the PBCH signal includes a frequency domain reception of the PBCH signal corresponding to each of the plurality of designated subframes. Each designated subframe comprises a plurality of OFDM symbols, and the frequency domain receiving PBCH signal corresponding to each designated subframe comprises a frequency domain receiving PBCH signal corresponding to each of the plurality of OFDM symbols.

Step 203, performing frequency offset estimation according to the local PBCH signal and the frequency domain received PBCH signal to obtain a frequency offset estimation result.

The user equipment receives the PBCH signal by using the local PBCH signal and the frequency domain as statistical samples, and carries out PBCH frequency offset estimation to obtain a frequency offset estimation result. And the frequency offset estimation result is determined based on the local PBCH signal and the frequency domain received PBCH signal.

To sum up, the embodiment of the present disclosure obtains, by a user equipment, a local PBCH signal and a frequency domain received PBCH signal, and performs frequency offset estimation according to the local PBCH signal and the frequency domain received PBCH signal to obtain a frequency offset estimation result, where the local PBCH signal includes a local PBCH signal corresponding to each of a plurality of estimation samples obtained by reconstruction, and the frequency domain received PBCH signal includes a frequency domain received PBCH signal corresponding to each of the plurality of received estimation samples; the user equipment takes the local PBCH signal obtained by reconstruction and the received frequency domain receiving PBCH signal as the statistic sample of PBCH frequency offset estimation, the coverage range of the scheme is increased by increasing the number of samples, the precision of the frequency offset estimation is improved, and the PBCH frequency offset estimation performance under low signal-to-noise ratio is effectively improved.

Referring to fig. 3, it shows a flowchart of a frequency offset estimation method provided in another exemplary embodiment of the present disclosure, which is used in the user equipment shown in fig. 1 for example. The method comprises the following steps.

Step 301, a local PBCH signal is obtained, where the local PBCH signal includes a local PBCH signal corresponding to each of the multiple reconstructed estimated samples.

And after the user equipment successfully resides in the service cell, acquiring MIB information corresponding to the service cell, and reconstructing according to the MIB information to obtain a local PBCH signal.

Optionally, the ue acquires MIB information corresponding to the serving cell according to the number of preset samples, and reconstructs a local PBCH signal according to the MIB information. The local PBCH signal includes local PBCH signals corresponding to respective estimated samples of a preset number of samples, where the preset number of samples is a positive integer greater than 1.

In an illustrative example, taking the estimation samples as the designated subframes (for example, subframe 0 or subframe 9) in the FDD mode as an example, if the number of the preset estimation samples is 10, the ue acquires the local PBCH signals corresponding to the 10 designated subframes. The local PBCH signal corresponding to each of the 10 designated subframes includes a local PBCH signal corresponding to each of the 14 OFDM symbols.

It should be noted that, for the process of acquiring the local PBCH signal by the ue, reference may be made to relevant details in the foregoing embodiments, and details are not described herein again.

Step 302, obtaining a frequency domain receiving PBCH signal, where the frequency domain receiving PBCH signal includes frequency domain receiving PBCH signals corresponding to the received multiple estimation samples.

Optionally, the user equipment receives time domain received data carrying the PBCH signal according to a preset number of samples; and performing time-frequency conversion on the time domain receiving data to obtain a frequency domain receiving PBCH signal.

The time domain receiving data is data of estimated samples with a preset number of samples in a time domain, the frequency domain receiving PBCH signals comprise frequency domain receiving PBCH signals corresponding to the estimated samples with the preset number of samples, and the preset number of samples is a positive integer greater than 1.

In an illustrative example, taking the estimation samples as the designated subframes (for example, subframe 0 or subframe 9) in the FDD mode as an example, if the number of the preset estimation samples is 10, the ue acquires the frequency domain received PBCH signals corresponding to the 10 designated subframes. The frequency domain receiving PBCH signal corresponding to each of the 10 designated subframes comprises frequency domain receiving PBCH signals corresponding to 14 OFDM symbols respectively.

It should be noted that, for the process of acquiring the PBCH signal in the frequency domain by the ue, reference may be made to relevant details in the foregoing embodiments, and details are not described herein again.

And 303, performing frequency coarse estimation according to the local PBCH signal and the frequency domain receiving PBCH signal to obtain a frequency coarse estimation value and a signal quality index.

And the user equipment performs frequency coarse estimation according to the local PBCH signal and the frequency domain receiving PBCH signal to obtain a frequency coarse estimation value and a signal quality index.

The frequency coarse estimation value is an estimation value determined by frequency offset estimation based on the local PBCH signal and the frequency domain receiving PBCH signal. The signal quality indicator is used to indicate the signal quality of the PBCH signal.

And step 304, determining a frequency offset estimation result according to the frequency rough estimation value and the signal quality index.

Optionally, the user equipment determines a frequency offset estimation result according to the frequency rough estimation value and the signal quality index. And the frequency offset estimation result is an estimation result determined by frequency offset estimation based on the frequency rough estimation value and the signal quality index.

Optionally, the

steps

303 and 304 may be alternatively implemented as the following steps, as shown in fig. 4:

step 401, determining frequency domain channel impulse responses corresponding to the multiple estimation samples according to the local PBCH signal and the frequency domain received PBCH signal.

Optionally, the determining, by the ue, frequency domain channel impulse responses corresponding to the multiple estimated samples according to the local PBCH signal and the frequency domain received PBCH signal includes: for each of a plurality of estimation samples, determining a frequency domain channel impulse response corresponding to each of a plurality of OFDM symbols of the estimation sample according to the local PBCH signal and the frequency domain received PBCH signal; for each of the multiple estimation samples, determining a frequency domain channel impulse response corresponding to each of multiple frequency domain resource units of the estimation sample according to a frequency domain channel impulse response corresponding to each of multiple OFDM symbols of the estimation sample.

Since the PBCH signal employs the transmit diversity scheme at the transmitting end, the following two possible calculation schemes can be adopted, but are not limited to, in calculating the frequency domain channel impulse response.

In one possible calculation manner, for each of a plurality of estimation samples, the user equipment receives the PBCH signal according to the local PBCH signal and the frequency domain, and calculates the frequency domain channel impulse response FH _ TX corresponding to each OFDM symbol of the estimation sample according to the following formula ₀ _INITAL：

FH_TX ₀ _INITAL＝LocalPBCH*conj(RecPBCH)

Where localbch is the local PBCH signal, recRBCH is the frequency domain received PBCH signal, and conj () is a function used to calculate the conjugate value.

In another possible calculation manner, if the antenna port is a single port, for each of the multiple estimation samples, the ue receives the PBCH signal according to the local PBCH signal and the frequency domain, and calculates the frequency domain channel impulse response FH _ TX corresponding to each OFDM symbol of the estimation sample according to the following formula ₀ _INITAL：

FH_TX ₀ _INITAL＝LocalPBCH*conj(RecPBCH)

If the antenna ports are two ports, for each estimation sample in the multiple estimation samples, the user equipment receives the PBCH signal according to the local PBCH signal and the frequency domain, and calculates according to the following formula to obtain the frequency domain channel impulse response corresponding to each OFDM symbol of the estimation sample, where the frequency domain channel impulse response corresponding to one OFDM symbol includes two values, i.e., FH _ TX ₀ INITAL and FH TX ₁ _INITAL：

FH_INITAL1＝LocalPBCH1*conj(RecPBCH1)+LocalPBCH2*conj(RecPBCH2)

FH_INITAL2＝-LocalPBCH2*(RecPBCH1)+LocalPBCH1*(RecPBCH2)

The RecRBCH1 represents a frequency domain receiving PBCH signal corresponding to a frequency domain odd position on one OFDM symbol, the RecRBCH2 represents a frequency domain receiving PBCH signal corresponding to a frequency domain even position on the OFDM symbol, the localbch 1 represents a local PBCH signal corresponding to a frequency domain odd position on the OFDM symbol, and the localbch 2 represents a local PBCH signal corresponding to a frequency domain even position on the OFDM symbol. The user equipment encrypts FH _ INITAL1 and FH _ INITAL2 by one time in a copying mode respectively to obtain a frequency domain channel impact response (FH _ TX) corresponding to the OFDM symbol ₀ INITAL and FH TX ₁ _INITAL。

Optionally, the frequency domain channel impulse responses corresponding to the multiple OFDM symbols respectively include: carrying full frequency domain position channel impact response corresponding to the OFDM symbol of the PBCH signal; and/or the full frequency domain position channel impulse response corresponding to the OFDM symbol which does not carry the PBCH signal.

In one possible implementation, the ue calculates a full frequency domain position channel impulse response corresponding to an OFDM symbol carrying a PBCH signal.

Because some frequency domain positions on the OFDM symbol corresponding to some PBCH signals need to map resources such as CRS, the PBCH signal corresponding to the OFDM symbol does not occupy all resource units, which is reflected as that the frequency domain channel impulse response in the OFDM symbol has no calculation result in the partial frequency domain position, i.e., the frequency domain channel impulse response of the OFDM symbol is discontinuous. In order to obtain the full-frequency-domain position channel impulse response corresponding to the OFDM symbol, the vacant frequency-domain channel impulse responses need to be supplemented, and may be obtained by interpolation using the adjacent full-frequency-domain position channel impulse response, or by frequency-domain Minimum Mean Square Error (MMSE), where the adopted method depends on the propagation channel characteristics and the applied difference. This embodiment is not limited thereto.

Optionally, the user equipment obtains the full-frequency-domain position channel impulse response corresponding to the OFDM symbol by using frequency-domain interpolation.

In one illustrative example, as shown in FIG. 5, the frequency domain channel impulse response FH _ TX _p The partial frequency domain position of the _initial51 in the OFDM symbol carrying the PBCH signal is not calculated, that is, the frequency domain channel impulse response 52 corresponding to the partial frequency domain position in the OFDM symbol is empty. For each frequency domain position in the partial frequency domain positions, acquiring a frequency domain channel impulse response 54 corresponding to the frequency domain position by utilizing the frequency domain channel impulse response 53 of the adjacent frequency domain position in an interpolation mode, supplementing the vacant frequency domain channel impulse response, and obtaining a full frequency domain position channel impulse response FH _ TX corresponding to the OFDM symbol _p _FNITER55。

In another possible implementation manner, the user equipment calculates the full-frequency-domain position channel impulse response corresponding to the OFDM symbol not carrying the PBCH signal.

Because some OFDM symbols need to map signals such as PSS or SSS, PBCH signals are not mapped to these OFDM symbols, which means that the frequency domain channel impulse response corresponding to the OFDM symbols is missing, and therefore, the full frequency domain position channel impulse response corresponding to the OFDM symbol that does not carry the PBCH signals needs to be obtained by using the full frequency domain position channel impulse response of the adjacent OFDM symbol that carries the PBCH signals through an interpolation method.

Optionally, the ue obtains the full-frequency-domain position channel impulse response corresponding to the OFDM symbol without PBCH signal mapped by using time-domain interpolation.

In an exemplary example, as shown in fig. 6, a frequency domain channel impulse response corresponding to an OFDM symbol not carrying a PBCH signal is absent, and a full frequency domain position channel impulse response FH _ TX of the OFDM symbol carrying the PBCH signal is utilized _p Obtaining full frequency domain position channel impulse response FH _ TX corresponding to the OFDM symbol by an interpolation mode _p _FNITER62。

Step 402, for each estimation sample in the multiple estimation samples, determining a time domain channel impulse response corresponding to the estimation sample according to a frequency domain channel impulse response corresponding to the estimation sample.

For each of the multiple estimated samples, the user equipment determines, according to frequency domain channel impulse responses corresponding to multiple OFDM symbols of the estimated sample, frequency domain channel impulse responses corresponding to multiple frequency domain resource units of the estimated sample. And determining time domain channel impact responses corresponding to the plurality of frequency domain resource units of the estimation sample according to the frequency domain channel impact responses corresponding to the plurality of frequency domain resource units of the estimation sample.

The frequency domain channel impulse response corresponding to the estimated sample comprises frequency domain channel impulse responses corresponding to a plurality of frequency domain resource units of the estimated sample, and the time domain channel impulse response corresponding to the estimated sample comprises time domain channel impulse responses corresponding to a plurality of frequency domain resource units of the estimated sample.

In an illustrative example, the estimation samples are subframes, and for each subframe of a plurality of subframes, the ue performs channel impulse response FH _ TX according to a full frequency domain position corresponding to each of a plurality of OFDM symbols of the subframe _p FNITER, determining frequency domain channel impulse response FH _ TX corresponding to each of multiple frequency domain resource units of the subframe _p TINTER. Determining a time domain channel impulse response TH _ TX corresponding to each of the plurality of frequency domain resource units of the subframe according to the frequency domain channel impulse response FH _ Txp _ TINTER corresponding to each of the plurality of frequency domain resource units of the subframe _p 。

Optionally, the frequency domain channel impulse response corresponding to each frequency domain resource unit in the estimation sample is a sequence of frequency domain channel impulse responses on different OFDM sequence numbers of the same frequency domain resource unit in the estimation sample.

Optionally, the frequency domain resource unit is a subcarrier. The frequency domain channel impulse response corresponding to the estimated sample comprises frequency domain channel impulse responses corresponding to a plurality of subcarriers of the estimated sample respectively, and the time domain channel impulse response corresponding to the estimated sample comprises time domain channel impulse responses corresponding to a plurality of subcarriers of the estimated sample respectively.

Optionally, for each estimated sample in the multiple estimated samples, the user equipment performs time-frequency transformation according to the frequency-domain channel impulse response corresponding to each of the multiple frequency-domain resource units of the estimated sample to obtain the frequency-domain channel impulse response of the estimated sampleAnd the time domain channel impact responses corresponding to the plurality of frequency domain resource units respectively. Illustratively, the UE will estimate FH _ TX at different OFDM sequence numbers of same frequency domain resource units in a sample _p The _TINTERforms a sequence, the sequence is the frequency domain channel impulse response corresponding to the frequency domain resource unit, and the sequence is subjected to IFFT (Inverse Fast Fourier Transform) of the preset IFFT points in a zero filling mode to obtain the corresponding time domain channel impulse response.

And 403, combining the time domain channel impulse responses corresponding to the multiple estimation samples to obtain a target superposition result.

In a possible implementation manner, a user equipment combines time domain channel impulse responses corresponding to a plurality of estimation samples to obtain a target superposition result, including: and performing incoherent superposition on the time domain channel impact responses of the same frequency domain resource units in the multiple estimation samples to obtain a target superposition result, wherein the target superposition result comprises target time domain channel impact responses corresponding to the multiple frequency domain resource units. The same frequency domain resource unit may be a frequency domain resource unit with the same position or the same number in each estimation sample, that is, for the ith frequency domain channel resource in one estimation sample, the time domain channel impulse responses of the ith frequency domain channel resource in multiple estimation samples are respectively subjected to incoherent superposition to obtain the target time domain channel impulse response corresponding to the frequency domain resource unit, where i is a positive integer.

And the target superposition result is a sequence comprising target time domain channel impulse responses corresponding to the plurality of frequency domain resource units respectively.

Optionally, the user equipment sends the time-domain channel impulse response TH _ TX of the same frequency-domain resource unit in each estimation sample _p Non-coherent superposition is carried out through the following formula to obtain a target superposition result TH _ POWER [ n ]]：

Wherein n =1,2, … …, NIFFTNum

Wherein p is the number of antenna ports, k is the number of Resource Elements (REs) in an estimation sample, the value range of k is 1 to 72, and k is a positive integer; n is the sequence length of the target superposition result, and NIFFTNum is the preset IFFT point number.

And step 404, determining a frequency coarse estimation value and a signal quality index according to the target superposition result.

Optionally, the user equipment determines the signal quality indicator according to a maximum value of multiple target time domain channel impulse responses in the target superposition result. And the user equipment determines a frequency coarse estimation value according to a target position number corresponding to the maximum value, wherein the target position number is used for indicating the position of the maximum value in the target superposition result.

Optionally, the determining, by the user equipment, the signal quality indicator according to the maximum value in the target superposition result includes: according to the maximum value in the target superposition result, determining a signal quality index SignalQualFac by the following formula:

wherein MaxValue is the maximum value, NIFFTNum is the IFFT point number that predetermines, TH _ POWER [ n ] is the target stack result, and the value range of n is 1 to NIFFTNum, and NIFFTNum is the positive integer that is greater than 1.

Optionally, the determining, by the user equipment, the coarse frequency estimation value according to the target location number corresponding to the maximum value includes: when the target position number is less than half of the preset IFFT point number, multiplying the target position number by the preset frequency granularity to obtain a frequency rough estimation value; and when the target position number is more than or equal to half of the IFFT point number, multiplying the target difference value by the frequency granularity to obtain a frequency coarse estimation value, wherein the target difference value is the difference value between the target position number and the IFFT point number.

The frequency granularity depends on the interpolation multiple adopted in time-frequency transformation.

Optionally, the user equipment determines the frequency rough estimation value EstCrudeFreq according to the target location number MaxIndex corresponding to the maximum value and the preset IFFT point number NIFFTNum by using the following formula:

EstCrudeFreq＝((MaxIndex<NIFFNum/2)？(MaxIndex*FreqGranularity):((MaxIndex-NIFFNum)*FreqGranularity)

wherein FreqGranularity is frequency granularity.

And 405, performing frequency offset fine estimation according to the frequency coarse estimation value and the signal quality index to obtain a frequency fine estimation value.

Optionally, the user equipment determines whether the signal quality indicator is higher than a quality indicator threshold, performs frequency offset fine estimation according to a first possible implementation manner described below if the signal quality indicator is higher than the quality indicator threshold, and performs frequency offset fine estimation according to a second possible implementation manner described below if the signal quality indicator is lower than or equal to the quality indicator threshold. This embodiment does not limit this.

In a first possible implementation manner, when the signal quality index is higher than the quality index threshold, the user equipment performs frequency offset correction on the frequency domain channel impact response according to the frequency rough estimation value to obtain the frequency domain channel impact response after the frequency offset correction. And performing frequency offset fine estimation according to the frequency domain channel impact response after the frequency offset correction to obtain a frequency fine estimation value.

Optionally, for each estimation sample in the multiple estimation samples, the user equipment performs frequency offset correction on frequency domain channel impulse responses corresponding to multiple OFDM symbols of the estimation sample according to the coarse frequency estimation value, so as to obtain frequency domain channel impulse responses after frequency offset correction corresponding to the multiple OFDM symbols of the estimation sample. And performing frequency offset fine estimation according to the frequency domain channel impact response after the frequency offset correction corresponding to each of the plurality of OFDM symbols of the estimation sample to obtain a frequency fine estimation value.

And the frequency domain channel impulse response corresponding to the OFDM symbol is the full frequency domain position channel impulse response corresponding to the OFDM symbol.

In an illustrative example, the estimated samples are subframes, and for each subframe in a plurality of subframes, the user equipment performs frequency domain channel impulse responses FH _ TX according to the frequency coarse estimation value estcrudlefreq to a plurality of OFDM symbols of the estimated samples respectively _p F, performing frequency offset correction to obtain the estimationFrequency domain channel impulse response FH _ TX after frequency offset correction corresponding to each of a plurality of OFDM symbols of sample _p Modify1. The frequency domain channel impulse response FH _ TX after the frequency deviation corresponding to each OFDM symbol carrying PBCH signals is corrected _p The _ Modify1 are arranged in sequence as shown in FIG. 7. The user equipment corrects the frequency domain channel impact response FH _ TX according to the frequency offset corresponding to each of a plurality of OFDM symbols of the estimation sample _p Modify1, and calculating a frequency fine estimation value EstFineFreq by the following formula:

wherein, PI is a circumference ratio; Δ t is the time interval of 3 OFDM symbols; k is the number of REs in an estimation sample, the value range of k is 1 to 72, and k is a positive integer; FH _ Modify1_ OFDM _ofdmstart+3 [k]For the frequency domain channel impulse response FH _ TX corrected by the frequency offset corresponding to the second OFDM symbol of dmstart +3 in the time domain in one estimation sample _p _Modify1；FH_Modify1_OFDM _ofdmstart [k]For a frequency domain channel impulse response FH _ TX corrected by the frequency offset corresponding to the second OFDM symbol of dmstart in the time domain in an estimation sample _p A Modify1; angle () is a function of the complex phase angle.

Wherein, the value of offstart is shown in table one. In table one, "Ncp" is used to indicate that a cyclic prefix type corresponding to PBCH is Normal cyclic prefix (Ncp), and "Ecp" is used to indicate that a cyclic prefix type corresponding to PBCH is extended cyclic prefix (Ecp).

Watch 1

In a second possible implementation manner, when the signal quality indicator is lower than or equal to the quality indicator threshold, the user equipment determines a noise area in the target superposition result according to the target location number corresponding to the maximum value. And carrying out zero setting on a plurality of target time domain channel impulse responses included in the noise region in the target superposition result to obtain the time domain channel impulse responses after the zero setting. And performing FFT operation on the time domain channel impulse response after the zero setting processing to obtain the frequency domain channel impulse response after the operation. And carrying out frequency offset correction on the operated frequency domain channel impact response according to the rough frequency offset estimation value to obtain the frequency domain channel impact response after frequency offset correction. And performing frequency offset fine estimation according to the frequency domain channel impact response after the frequency offset correction to obtain a frequency fine estimation value.

Optionally, when the signal quality indicator is lower than or equal to the quality indicator threshold, the user equipment determines a signal region and a noise region other than the signal region in the target superposition result according to the target position number and the preset value corresponding to the maximum value. The signal area comprises a plurality of target time domain channel impulse responses between a first position number and a second position number, the first position number is a difference value between the target position number and a preset value, the second position number is a sum of the target position number and the preset value, and the preset value is a positive integer.

Optionally, the user equipment performs frequency offset correction on the operated frequency domain channel impact response according to the coarse frequency offset estimation value to obtain the frequency domain channel impact response after frequency offset correction; the process of performing the frequency offset fine estimation according to the frequency domain channel impulse response after the frequency offset correction to obtain the frequency fine estimation value may refer to the relevant details in the first possible implementation manner, and is not described herein again.

And step 406, determining a frequency offset estimation result according to the frequency rough estimation value and the frequency fine estimation value.

Optionally, the user equipment determines the sum of the frequency rough estimation value and the frequency fine estimation value as the frequency offset estimation result.

In an illustrative example, a flow chart of a frequency offset estimation method as shown in fig. 8, which is used in a user equipment, includes but is not limited to the following steps: and step 801, reconstructing to obtain a local PBCH signal. Step 802, acquiring a frequency domain received PBCH signal. Step 803, a frequency domain channel impulse response corresponding to each of the plurality of estimated samples is calculated. Step 804, a full frequency domain position channel impulse response corresponding to each of the plurality of OFDM symbols is obtained using frequency domain interpolation. Step 805, obtaining the full frequency domain position channel impulse response corresponding to the OFDM symbol of the unmapped PBCH signal by using time domain interpolation. Step 806, calculating time domain channel impulse responses corresponding to the plurality of estimation samples. In step 807, the time domain channel impulse responses corresponding to the multiple estimation samples are combined to obtain a target superposition result. And 808, calculating a frequency rough estimation value and a signal quality index. Step 809 determines whether the signal quality indicator is above a quality indicator threshold, if the signal quality indicator is above the quality indicator threshold, step 810 is performed, and if the signal quality indicator is below or equal to the quality indicator threshold, step 812 is performed. And 810, performing frequency offset correction on the frequency domain channel impact response FH according to the coarse frequency estimation value to obtain a frequency domain channel impact response FH _ Modify1 after the frequency offset correction. In step 811, frequency offset fine estimation is performed using FH _ Modify1 to obtain a frequency fine estimation value, and step 816 is performed. In step 812, the noise region is zeroed to obtain a time domain channel impulse response TH _ modification 1 after the zeroed processing. Step 813, performing FFT operation using TH _ modification 1 to obtain the frequency domain channel impulse response FH _ modification 2 after the operation. And 814, performing frequency offset correction on the FH _ Modify2 by using the coarse frequency offset estimation value to obtain a frequency domain channel impact response FH _ Modify3 after the frequency offset correction. Step 815, performing frequency offset fine estimation by using FH _ Modify3 to obtain a frequency fine estimation value. Step 816, calculating a frequency offset estimation result according to the frequency rough estimation value and the frequency fine estimation value.

In summary, on one hand, samples (e.g., PSS/SSS/CRS) used by the conventional frequency offset estimation scheme in the prior art are limited, and since the design of physical signals such as PSS/SSS/CRS under the eMTC system is still the same as that of the conventional LTE system, this means that the signals are reused as estimation samples, which obviously does not show the pertinence of the design of the eMTC system. The frequency offset estimation method is designed based on eMTC system design characteristics, repeated PBCH specially designed for the eMTC system is selected as an estimation sample, and the frequency offset estimation method is designed based on PBCH mapping characteristics, so that more estimation sample numbers can be obtained within fixed time, noise influence is smoothed to a certain extent, and the coverage capability of the scheme is enhanced.

On the other hand, the frequency offset estimation method provided by the embodiment of the disclosure improves the frequency offset estimation capability from-6 db to-15 db, and solves the problems of insufficient robustness and poor estimation performance of the frequency offset estimation method in the related art in a weak signal scene. Secondly, the embodiment of the disclosure solves the problem of initial large frequency offset caused by low power consumption, not only improves the frequency offset estimation range to meet the system requirement, but also solves the problem of individual contradiction between the estimation range and the estimation performance in the related technology, so that the two variables can coexist optimally, and on the premise of meeting the estimation range, the estimation performance is not deteriorated, and the estimation performance can be improved as much as possible.

On the other hand, the initial frequency offset brought by the low power consumption design of the system exceeds the design specification of the traditional frequency offset estimation scheme, and the maximum frequency offset estimation capability of the traditional frequency offset estimation scheme is limited: if the phase difference scheme is used, the maximum estimation capability is only about 1kHZ, and if the maximum likelihood estimation scheme is used, the frequency offset estimation capability can be infinitely large, but this also means an infinite increase in complexity, which is obviously difficult to use in practice. In the embodiment of the disclosure, the frequency coarse estimation value and the signal quality index are obtained by performing frequency coarse estimation according to the local PBCH signal and the frequency domain receiving PBCH signal, so that the frequency offset estimation capacity is improved to about 7kHZ through the coarse estimation step, and the system design requirement is met.

On the other hand, the embodiment of the disclosure also solves the problem of insufficient estimation robustness of the frequency offset estimation method in the related art in the weak coverage scene through the specific design of the rough estimation step, and ensures that the estimation variance is controllable. The embodiment of the disclosure also ensures that the residual frequency offset is very small when the frequency fine estimation is carried out through the coarse estimation step, and solves the problem that the two variables of the estimation range and the estimation performance are contradictory in the fine estimation step.

On the other hand, the embodiment of the present disclosure further determines a noise area in the target superposition result according to the target position number corresponding to the maximum value when the signal quality index is lower than or equal to the quality index threshold; carrying out zero setting processing on a plurality of target time domain channel impact responses included in a noise region in a target superposition result to obtain a time domain channel impact response after the zero setting processing; performing FFT operation on the time domain channel impulse response after the zero setting processing to obtain the frequency domain channel impulse response after the operation; carrying out frequency offset correction on the operated frequency domain channel impact response according to the rough frequency offset estimation value to obtain the frequency domain channel impact response after frequency offset correction; performing frequency offset fine estimation according to the frequency domain channel impact response after the frequency offset correction to obtain a frequency fine estimation value; therefore, the noise processing is eliminated through the fine estimation step, and the problem of poor estimation performance under weak signals in the related technology is solved.

On the other hand, in the conventional frequency offset estimation scheme in the prior art, the frequency offset estimation range and the estimation performance are a pair of contradictory individuals, the larger the estimation range is, the worse the estimation performance is, and in the application scenario, in order to satisfy such a large estimation deviation, the estimation performance in the conventional frequency offset estimation scheme is inevitably deteriorated. The embodiment of the disclosure also combines the respective characteristics of the frequency rough estimation step and the frequency fine estimation step to simultaneously meet the requirements of the estimation range and the estimation performance.

On the other hand, the embodiment of the disclosure further determines whether the signal quality index is higher than the quality index threshold value through the user equipment, so that different implementation modes are adopted to perform frequency offset fine estimation to obtain a frequency fine estimation value, the frequency fine estimation value obtained by the frequency offset fine estimation is more accurate, and the accuracy of the frequency offset estimation result determined based on the frequency fine estimation value is further ensured.

The following are embodiments of the apparatus of the embodiments of the present disclosure, and for portions of the embodiments of the apparatus not described in detail, reference may be made to technical details disclosed in the above-mentioned method embodiments.

Referring to fig. 9, a schematic structural diagram of a frequency offset estimation apparatus according to an exemplary embodiment of the present disclosure is shown. The frequency offset estimation apparatus can be implemented by software, hardware or a combination of both as all or part of the user equipment. The frequency offset estimation device comprises: a first acquisition module 910, a second acquisition module 920, and an estimation module 930.

A first obtaining module 910, configured to obtain a local PBCH signal, where the local PBCH signal includes a local PBCH signal corresponding to each of multiple reconstructed estimation samples;

a second obtaining module 920, configured to obtain a frequency-domain received PBCH signal, where the frequency-domain received PBCH signal includes frequency-domain received PBCH signals corresponding to the received multiple estimation samples;

and an estimating module 930, configured to perform frequency offset estimation according to the local PBCH signal and the frequency domain received PBCH signal, so as to obtain a frequency offset estimation result.

In one possible implementation, the estimating module 930 is further configured to:

and determining a frequency offset estimation result according to the frequency rough estimation value and the signal quality index.

In another possible implementation, the estimating module 930 is further configured to

Determining frequency domain channel impulse responses corresponding to the multiple estimation samples according to the local PBCH signal and the frequency domain receiving PBCH signal;

for each estimation sample in the multiple estimation samples, determining a time domain channel impulse response corresponding to the estimation sample according to a frequency domain channel impulse response corresponding to the estimation sample;

merging time domain channel impact responses corresponding to the multiple estimation samples to obtain a target superposition result;

and determining a frequency rough estimation value and a signal quality index according to the target superposition result.

In another possible implementation manner, estimating the frequency domain channel impulse response corresponding to the sample includes estimating frequency domain channel impulse responses corresponding to a plurality of frequency domain resource units of the sample, and estimating the time domain channel impulse response corresponding to the sample includes estimating time domain channel impulse responses corresponding to a plurality of frequency domain resource units of the sample;

the estimating module 930 is further configured to perform incoherent superposition on the time domain channel impulse responses of the same frequency domain resource units in the multiple estimation samples to obtain a target superposition result, where the target superposition result includes target time domain channel impulse responses corresponding to the multiple frequency domain resource units.

In another possible implementation, the estimating module 930 is further configured to, for each of a plurality of estimated samples, determine, according to the local PBCH signal and the frequency-domain received PBCH signal, a frequency-domain channel impulse response corresponding to each of a plurality of OFDM symbols of the estimated sample;

and for each estimation sample in the plurality of estimation samples, determining frequency domain channel impulse responses corresponding to a plurality of frequency domain resource units of the estimation sample according to the frequency domain channel impulse responses corresponding to a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols of the estimation sample.

In another possible implementation manner, the frequency domain channel impulse responses corresponding to the multiple OFDM symbols respectively include:

In another possible implementation manner, the estimating module 930 is further configured to determine a signal quality indicator according to a maximum value of multiple target time domain channel impulse responses in the target superposition result; and determining a frequency coarse estimation value according to a target position number corresponding to the maximum value, wherein the target position number is used for indicating the position of the maximum value in the target superposition result.

In another possible implementation manner, the estimating module 930 is further configured to determine, according to a maximum value in the target superposition result, a signal quality indicator SignalQualFactor according to the following formula:

wherein, maxValue is the maximum value, and NIFFTNum is the IFFT point number of predetermined inverse fast Fourier transform, and TH _ POWER [ n ] is the target stack result, and the value range of n is 1 to NIFFTNum, and NIFFTNum is for being greater than 1 positive integer.

In another possible implementation manner, the estimating module 930 is further configured to:

when the target position number is less than half of the preset IFFT point number, multiplying the target position number by the preset frequency granularity to obtain a frequency rough estimation value;

and when the target position number is more than or equal to half of the IFFT points, multiplying the target difference value by the frequency granularity to obtain a frequency coarse estimation value, wherein the target difference value is the difference value between the target position number and the IFFT points.

and determining a frequency offset estimation result according to the frequency rough estimation value and the frequency fine estimation value.

In another possible implementation manner, the estimating module 930 is further configured to, when the signal quality index is higher than the quality index threshold, perform frequency offset correction on the frequency domain channel impulse response according to the coarse frequency estimation value, to obtain a frequency domain channel impulse response after the frequency offset correction; and performing frequency offset fine estimation according to the frequency domain channel impact response after the frequency offset correction to obtain a frequency fine estimation value.

when the signal quality index is lower than or equal to the quality index threshold, determining a noise area in a target superposition result according to a target position number corresponding to the maximum value;

carrying out zero setting processing on a plurality of target time domain channel impact responses included in a noise region in a target superposition result to obtain a time domain channel impact response after the zero setting processing;

carrying out Fast Fourier Transform (FFT) operation on the time domain channel impulse response after the zero setting processing to obtain the frequency domain channel impulse response after the operation;

carrying out frequency offset correction on the operated frequency domain channel impact response according to the rough frequency offset estimation value to obtain the frequency domain channel impact response after frequency offset correction;

and performing frequency offset fine estimation according to the frequency domain channel impact response after the frequency offset correction to obtain a frequency fine estimation value.

and determining the sum of the frequency rough estimation value and the frequency fine estimation value as a frequency offset estimation result.

In another possible implementation manner, the first obtaining module 910 is further configured to obtain MIB information of a main system information block corresponding to a serving cell after the serving cell is successfully camped; and reconstructing to obtain a local PBCH signal according to the MIB information.

In another possible implementation manner, the second obtaining module 920 is configured to receive time-domain received data carrying a PBCH signal, where the time-domain received data is data of multiple estimation samples in a time domain; and performing time-frequency conversion on the time domain receiving data to obtain a frequency domain receiving PBCH signal.

It should be noted that, when the apparatus provided in the foregoing embodiment implements the functions thereof, only the division of the above functional modules is illustrated, and in practical applications, the above functions may be distributed by different functional modules according to actual needs, that is, the content structure of the device is divided into different functional modules, so as to complete all or part of the functions described above.

With regard to the apparatus in the above-described embodiment, the specific manner in which each module performs the operation has been described in detail in the embodiment related to the method, and will not be elaborated here.

Referring to fig. 10, a schematic structural diagram of a user equipment according to an exemplary embodiment of the present disclosure is shown, where the user equipment may be the user equipment 140 in the mobile communication system shown in fig. 1. In this embodiment, a user equipment is taken as an example of a UE in an LTE system or a 5G system for explanation, where the user equipment includes: a processor 101, a receiver 102, a transmitter 103, a memory 104, and a bus 105. The memory 104 is connected to the processor 101 through a bus 105.

The processor 101 includes one or more processing cores, and the processor 101 executes various functional applications and information processing by running software programs and modules.

The receiver 102 and the transmitter 103 may be implemented as a communication component, which may be a communication chip, and the communication chip may include a receiving module, a transmitting module, a modulation and demodulation module, and the like, for modulating and/or demodulating information and receiving or transmitting the information through a wireless signal.

Memory 104 may be used to store processor 101 executable instructions.

Memory 104 may store at least one application module 106 that functions as described. The application module 106 may include: a first acquisition module 1061, a second acquisition module 1062, and an estimation module 1063.

The processor 101 is configured to execute the first obtaining module 1061 and the second obtaining module 1062 to implement the functions of the obtaining step performed by the ue in the foregoing method embodiments; the processor 101 is configured to execute the estimation module 1063 to implement the functions related to the estimation step performed by the user equipment in the above-described method embodiments.

Further, the memory 104 may be implemented by any type or combination of volatile and non-volatile memory devices, such as Static Random Access Memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic or optical disks.

An embodiment of the present disclosure further provides a user equipment, where the user equipment includes: a processor; a memory for storing processor-executable instructions;

wherein the processor is configured to implement the steps performed by the user equipment in the above-described method embodiments.

The disclosed embodiments also provide a non-transitory computer-readable storage medium, on which computer program instructions are stored, and when executed by a processor, the computer program instructions implement the steps performed by the user equipment in the above method embodiments.

The present disclosure may be systems, methods, and/or computer program products. The computer program product may include a computer-readable storage medium having computer-readable program instructions embodied thereon for causing a processor to implement various aspects of the present disclosure.

The computer-readable storage medium may be a tangible device that can hold and store the instructions for use by the instruction execution device. The computer readable storage medium may be, for example, but not limited to, an electronic memory device, a magnetic memory device, an optical memory device, an electromagnetic memory device, a semiconductor memory device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a Static Random Access Memory (SRAM), a portable compact disc read-only memory (CD-ROM), a Digital Versatile Disc (DVD), a memory stick, a floppy disk, a mechanical coding device, such as a punch card or an in-groove protruding structure with instructions stored thereon, and any suitable combination of the foregoing. Computer-readable storage media as used herein is not to be construed as transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission medium (e.g., optical pulses through a fiber optic cable), or electrical signals transmitted through electrical wires.

The computer-readable program instructions described herein may be downloaded from a computer-readable storage medium to a respective computing/processing device, or to an external computer or external storage device over a network, such as the internet, a local area network, a wide area network, and/or a wireless network. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. The network adapter card or network interface in each computing/processing device receives computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in a computer-readable storage medium in the respective computing/processing device.

The computer program instructions for carrying out operations of the present disclosure may be assembler instructions, instruction Set Architecture (ISA) instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider). In some embodiments, the electronic circuitry that can execute the computer-readable program instructions implements aspects of the present disclosure by utilizing the state information of the computer-readable program instructions to personalize the electronic circuitry, such as a programmable logic circuit, a Field Programmable Gate Array (FPGA), or a Programmable Logic Array (PLA).

Various aspects of the present disclosure are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer-readable program instructions.

These computer-readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable medium storing the instructions comprises an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer, other programmable apparatus or other devices implement the functions/acts specified in the flowchart and/or block diagram block or blocks.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

Having described embodiments of the present disclosure, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein were chosen in order to best explain the principles of the embodiments, the practical application, or technical improvements to the techniques in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for frequency offset estimation, used in a user equipment, the method comprising:

performing frequency offset estimation according to the local PBCH signal and the frequency domain received PBCH signal to obtain a frequency offset estimation result;

the frequency offset estimation according to the local PBCH signal and the frequency domain received PBCH signal to obtain a frequency offset estimation result, including:

performing frequency coarse estimation according to the local PBCH signal and the frequency domain receiving PBCH signal to obtain a frequency coarse estimation value and a signal quality index, wherein the frequency coarse estimation value is an estimation value determined by performing frequency offset estimation on the basis of the local PBCH signal and the frequency domain receiving PBCH signal, and the signal quality index is used for indicating the signal quality of the PBCH signal;

determining the frequency offset estimation result according to the frequency rough estimation value and the signal quality index;

the frequency coarse estimation according to the local PBCH signal and the frequency domain received PBCH signal to obtain a frequency coarse estimation value and a signal quality index includes:

2. The method of claim 1, wherein the frequency-domain channel impulse response corresponding to the estimation sample comprises a frequency-domain channel impulse response corresponding to each of a plurality of frequency-domain resource units of the estimation sample, and the time-domain channel impulse response corresponding to the estimation sample comprises a time-domain channel impulse response corresponding to each of the plurality of frequency-domain resource units of the estimation sample;

3. The method of claim 2, wherein determining frequency domain channel impulse responses for each of the plurality of estimated samples based on the local PBCH signal and the frequency domain received PBCH signal comprises:

for each of the plurality of estimation samples, determining a frequency domain channel impulse response corresponding to each of a plurality of orthogonal frequency division multiplexing, OFDM, symbols of the estimation sample from the local PBCH signal and the frequency domain received PBCH signal;

for each of the multiple estimation samples, determining a frequency domain channel impulse response corresponding to each of the multiple frequency domain resource units of the estimation sample according to a frequency domain channel impulse response corresponding to each of multiple OFDM symbols of the estimation sample.

4. The method of claim 3, wherein the frequency domain channel impulse responses for each of the plurality of OFDM symbols comprises:

5. The method of claim 2, wherein the determining the coarse frequency estimate and the signal quality indicator according to the target superposition result comprises:

6. The method of claim 5, wherein the determining the signal quality indicator according to the maximum value in the target superposition result comprises:

7. The method according to claim 5, wherein said determining the coarse frequency estimation value according to the target location number corresponding to the maximum value comprises:

and when the target position number is more than or equal to half of the IFFT point number, multiplying a target difference value by the frequency granularity to obtain the frequency coarse estimation value, wherein the target difference value is the difference value between the target position number and the IFFT point number.

8. The method of claim 2, wherein the determining the frequency offset estimation result according to the coarse frequency estimation value and the signal quality indicator comprises:

9. The method of claim 8, wherein performing a frequency offset fine estimation according to the coarse frequency estimation value and the signal quality indicator to obtain a fine frequency estimation value comprises:

10. The method of claim 8, wherein performing a frequency offset fine estimation according to the coarse frequency estimation value and the signal quality indicator to obtain a fine frequency estimation value comprises:

when the signal quality index is lower than or equal to a quality index threshold, determining a noise region in the target superposition result according to a target position number corresponding to a maximum value, wherein the maximum value is the maximum value of multiple target time domain channel impulse responses in the target superposition result, and the target position number is used for indicating the position of the maximum value in the target superposition result;

performing Fast Fourier Transform (FFT) operation on the time domain channel impact response after the zero setting processing to obtain an operated frequency domain channel impact response;

performing frequency offset correction on the operated frequency domain channel impact response according to the frequency rough estimation value to obtain the frequency domain channel impact response after the frequency offset correction;

11. The method of claim 8, wherein determining the frequency offset estimation result according to the coarse frequency estimation value and the fine frequency estimation value comprises:

12. The method of claim 1, wherein the acquiring the local PBCH signal comprises:

after the service cell is successfully resided, acquiring main system information block (MIB) information corresponding to the service cell;

13. The method of claim 1, wherein the obtaining the frequency domain received PBCH signal comprises:

14. A frequency offset estimation apparatus, for use in a user equipment, the apparatus comprising:

a first obtaining module, configured to obtain a local PBCH signal, where the local PBCH signal includes a local PBCH signal corresponding to each of multiple reconstructed estimation samples;

the estimation module is used for carrying out frequency offset estimation according to the local PBCH signal and the frequency domain receiving PBCH signal to obtain a frequency offset estimation result;

the estimation module is further configured to:

15. A user equipment, the user equipment comprising: a processor; a memory for storing processor-executable instructions;

wherein the processor is configured to:

the frequency coarse estimation is performed according to the local PBCH signal and the frequency domain receiving PBCH signal to obtain a frequency coarse estimation value and a signal quality index, and the method comprises the following steps:

16. A non-transitory computer readable storage medium having stored thereon computer program instructions, wherein the computer program instructions, when executed by a processor, implement the method of any one of claims 1 to 13.