CN112888047B

CN112888047B - PRACH signal processing method, device, communication equipment and storage medium

Info

Publication number: CN112888047B
Application number: CN202110469870.3A
Authority: CN
Inventors: 钱斌; 刘波; 邹刚; 干永刚; 荣元政
Original assignee: Wuxi Xinglian Xintong Technology Co ltd; Chengdu Xinglian Xintong Technology Co ltd
Current assignee: Wuxi Xinglian Xintong Technology Co.,Ltd.
Priority date: 2021-04-29
Filing date: 2021-04-29
Publication date: 2021-08-06
Anticipated expiration: 2041-04-29
Also published as: CN112888047A

Abstract

The invention relates to the technical field of communication, and provides a PRACH signal processing method, a device, communication equipment and a storage medium, wherein the PRACH signal processing method applied to a signal receiving end comprises the following steps: receiving a PRACH signal sent by a signal sending end, wherein the PRACH signal consists of the same pilot sequences with preset number; intercepting a plurality of pilot sequences in the PRACH signal according to the position of a preset window; calculating a PDP value corresponding to each position of a preset window according to a plurality of leader sequences corresponding to each position of the preset window; and detecting whether an access signal exists according to the maximum value in the PDP values corresponding to all the positions of the preset window. The invention adopts a brand-new PRACH signal format, is not limited by the contradiction between the transmission delay and the subcarrier interval size, and can realize the accurate detection of the access signal in a large-delay scene.

Description

PRACH signal processing method, device, communication equipment and storage medium

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a PRACH signal processing method, apparatus, communication device, and storage medium.

Background

Compared with a ground communication system, the low-orbit satellite system has larger transmission delay, and can be mainly used as a random access channel of LTE/NR (long term evolution/noise ratio) which is taken as a random access reference of a low-orbit broadband system at present. The PRACH signal of LTE/NR is composed of Cyclic Prefix (CP) and preamble, followed by Guard Time (GT, Guard Time) for protecting the random access signal from falling into the same detection window after delay. The difference between the length of the PRACH signal and the length of the detection window is the guard time. The leader sequences of LTE/NR adopt ZC sequences.

When the transmission delay in the low-orbit satellite system is too large, the PRACH format of LTE/NR can not meet the timing requirement of a base station for a user, if the CP length is greater than the transmission delay, the pilot length is too large, the pilot length causes the frequency interval between pilot subcarriers to be too small, the pilot subcarriers are easily affected by frequency offset, and finally the access signal detection is failed.

Disclosure of Invention

The invention aims to provide a PRACH signal processing method, a device, communication equipment and a storage medium, wherein a brand-new PRACH signal format is adopted, the PRACH signal format consists of a preset number of identical pilot sequences, the PRACH signal received by a signal receiving end corresponding to each sliding position of a sliding window is processed in a sliding window mode to obtain a corresponding PDP value, and accurate detection of an access signal is realized according to the PDP value.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

in a first aspect, the present invention provides a PRACH signal processing method, which is applied to a signal receiving end, where the signal receiving end is in communication connection with a signal transmitting end, and the method includes: receiving the PRACH signal sent by the signal sending end, wherein the PRACH signal consists of a preset number of identical pilot sequences, each pilot sequence is obtained by carrying out time domain-frequency domain conversion on a ZC sequence, and the ZC sequence is generated according to a preset root value; intercepting a plurality of pilot sequences in the PRACH signal according to the position of a preset window, wherein the position of the preset window comprises the current position and the position of each sliding when sliding for a preset number of times from the current position; calculating a PDP value corresponding to each position of the preset window according to the plurality of leader sequences corresponding to each position of the preset window; and detecting whether an access signal exists according to the maximum value in the PDP values corresponding to all the positions of the preset window.

In a second aspect, the present invention provides a PRACH signal processing method, which is applied to a signal transmitting end, where the signal transmitting end is in communication connection with a signal receiving end, and the method includes: generating a ZC sequence according to a preset root value; carrying out time domain-frequency domain conversion on the ZC sequence to obtain a pilot sequence; and forming PRACH signals by the preset number of pilot sequences and sending the PRACH signals to the signal receiving end.

In a third aspect, the present invention provides a PRACH signal processing apparatus, which is applied to a signal receiving end, where the signal receiving end is in communication connection with a signal transmitting end, and the apparatus includes: a receiving module, configured to receive a PRACH signal sent by the signal sending end, where the PRACH signal is composed of a preset number of identical preamble sequences, each of the preamble sequences is obtained by performing time-frequency domain conversion on a ZC sequence, and the ZC sequence is generated according to a preset root; a processing module, configured to intercept multiple preamble sequences in the PRACH signal according to a position of a preset window, where the position of the preset window includes a current position and a position where sliding is performed for a preset number of times from the current position; the processing module is further configured to calculate a PDP value corresponding to each position of the preset window according to the plurality of preamble sequences corresponding to each position of the preset window; and the detection module detects whether an access signal exists according to the maximum value in the PDP values corresponding to all the positions of the preset window.

In a fourth aspect, the present invention provides a PRACH signal processing apparatus, which is applied to a signal transmitting end, where the signal transmitting end is in communication connection with a signal receiving end, and the apparatus includes: the signal generation module is used for generating a ZC sequence according to a preset root value; the signal generation module is used for carrying out time domain-frequency domain conversion on the ZC sequence to obtain a pilot sequence; and the sending module is used for forming the PRACH signals by the preset number of pilot sequences and sending the PRACH signals to the signal receiving end.

In a fifth aspect, the present invention provides a communication device, including a memory and a processor, where the memory stores a computer program, and the processor implements the PRACH signal processing method applied to a signal receiving end or the signal transmitting end as described above when executing the computer program.

In a sixth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored, which, when executed by a processor, implements the PRACH signal processing method applied to a signal receiving end as described above, or implements the PRACH signal processing method applied to a signal transmitting end as described above.

Compared with the prior art, the invention adopts a brand-new PRACH signal format which consists of the same pilot sequences with the preset number, and the PRACH signal format does not have CP, so the pilot sequences are not limited by contradiction between transmission delay and subcarrier interval size, and simultaneously the PRACH signal received by a signal receiving end corresponding to each sliding position of a sliding window is processed by utilizing a sliding window mode to obtain a corresponding PDP value, and the accurate detection of the access signal is realized according to the PDP value.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a diagram illustrating an NR PRACH channel format according to the prior art according to an embodiment of the present invention.

Fig. 2 is a diagram illustrating an NR PRACH signal transmission procedure in the prior art according to an embodiment of the present invention.

Fig. 3 is a diagram illustrating an exemplary NR receiving end detection window according to an embodiment of the present invention.

Fig. 4 is a diagram illustrating an NR PRACH signal reception procedure according to the prior art according to an embodiment of the present invention.

Fig. 5 is an exemplary diagram of an improved PRACH channel format according to an embodiment of the present invention.

Fig. 6 is an exemplary diagram of a PRACH signal processing procedure applied to a signal transmitting end according to an embodiment of the present invention.

Fig. 7 is an exemplary diagram of a process flow for obtaining a preamble sequence according to an embodiment of the present invention.

Fig. 8 is a diagram illustrating an improved PRACH signal transmission procedure according to an embodiment of the present invention.

Fig. 9 is an exemplary diagram of a PRACH signal processing procedure applied to a signal receiving end according to an embodiment of the present invention.

Fig. 10 is a diagram illustrating a sliding example of a default window according to an embodiment of the present invention.

Fig. 11 is an exemplary diagram of a processing flow for calculating a PDP value corresponding to each position of a preset window according to an embodiment of the present invention.

Fig. 12 is an exemplary diagram of three-peak combining according to an embodiment of the present invention.

Fig. 13 is a diagram illustrating an improved PRACH signal reception procedure according to an embodiment of the present invention.

Fig. 14(a) is an exemplary diagram of a PDP with preset window positions after the first sliding window according to an embodiment of the present invention.

Fig. 14(b) is an exemplary diagram of a PDP with a preset window position after the second sliding window according to an embodiment of the present invention.

Fig. 14(c) is an exemplary diagram of a PDP with a preset window position after the third sliding window according to an embodiment of the present invention.

Fig. 15 is a diagram of detection probability of an access signal according to an embodiment of the present invention.

Fig. 16 is a block diagram of a first PRACH signal processing apparatus according to an embodiment of the present invention.

Fig. 17 is a block diagram of a second PRACH signal processing apparatus according to an embodiment of the present invention.

Fig. 18 is a block diagram of a communication device according to an embodiment of the present invention.

Icon: 10-a communication device; 11-a processor; 12-a memory; 13-a bus; 14-a communication interface; 100-a first PRACH signal processing means; 110-a signal generation module; 120-a sending module; 200-second PRACH signal processing means; 210-a receiving module; 220-a processing module; 230-detection module.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. indicate an orientation or a positional relationship based on that shown in the drawings or that the product of the present invention is used as it is, this is only for convenience of description and simplification of the description, and it does not indicate or imply that the device or the element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention.

Furthermore, the appearances of the terms "first," "second," and the like, if any, are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

It should be noted that the features of the embodiments of the present invention may be combined with each other without conflict.

In the prior art, for an application scenario with a large delay, such as a low-orbit broadband system, a Random Access reference of the system is a Random Access Channel of a Long Term Evolution (LTE) technology or a New Radio (NR) technology, and Physical Random Access Channel (PRACH) signals of the LTE/NR are both composed of a Cyclic Prefix (CP) and a preamble sequence, and then a Guard Time GT (Guard Time, GT) is used for protecting the Random Access signals from falling into the same detection window after being delayed. The difference between the length of the PRACH signal and the length of the detection window is the guard time. The leader sequences of LTE/NR adopt ZC sequences.

The generation flow of the leader sequence is as follows: after generating a basic time domain ZC sequence, performing Discrete Fourier Transform (DFT) operation on the ZC sequence to convert the ZC sequence into a Frequency domain, then mapping Frequency domain data after DFT to corresponding subcarriers according to subcarrier configuration allocated to a PRACH by a system, then performing Inverse Fast Fourier Transform (IFFT) operation to perform Orthogonal Frequency Division Multiplexing (OFDM) modulation to generate a time domain basic preamble sequence, finally repeating the preamble sequence for several times according to a required PRACH frame format, and finally adding a CP to assemble a baseband PRACH signal.

Generally, a specific PRACH channel format adopted in an actual application environment is related to a cell coverage radius, generally, a longer sequence can obtain a better coverage range, but a larger coverage range requires a longer CP and a GT to offset a corresponding round trip delay, the larger the cell coverage range is, the longer the transmission delay is, the larger the GT is, and a relationship constraint principle of a random access preamble sequence format and the cell coverage range is as follows: the transmission delay of the edge users in the cell needs to be inside the GT to ensure that the PRACH can be received normally. To meet different coverage requirements, the 38.211 protocol specifies PRACH parameters (cyclic prefix length, preamble length, and GT length) in 5 formats, please refer to fig. 1, fig. 1 is an exemplary diagram of a prior art NR PRACH channel format according to an embodiment of the present invention, and fig. 1 is an NR PRACH channel format of format 1 in the above 5 formats.

As a specific embodiment, a procedure for transmitting an NR PRACH signal may refer to fig. 2, where fig. 2 is an exemplary diagram of a procedure for transmitting an NR PRACH signal in the prior art according to an embodiment of the present invention, and in fig. 2, the signal is transmitted according to an embodiment of the present inventionThe number sending end firstly selects the root value of a ZC sequence according to the system configuration

And

generating a ZC sequence by equal parameters, then performing DFT operation on the ZC sequence to map the ZC sequence to a frequency domain, then mapping the ZC sequence to different subcarriers according to system configuration, performing OFDM modulation through IFFT operation, and finally forming a PRACH baseband signal according to the frame format of the PRACH.

A plurality of different sending windows are specified in the NR system, after synchronizing with a downlink signal, a User Equipment UE (User Equipment, UE) sends a PRACH access signal at the time of the sending window, and a detection window is set for reception at a base station end (i.e., a signal receiving end), and the configuration of the base station ensures that the time delay of User signals in the cell is not greater than the GT length, so that all User signals in the cell fall within the same detection window. Referring to fig. 3, fig. 3 is a diagram illustrating an exemplary NR receiving end detection window according to an embodiment of the present invention.

After receiving the NR PRACH signal, the signal receiving end intercepts the desired signal in the detection window, performs FFT operation to demodulate OFDM symbols, then performs demapping on subcarriers, extracts the PRACH signal on corresponding subcarriers, then multiplies the PRACH signal by a DFT conjugate of a local ZC sequence, performs IDFT operation to form a time domain correlation sequence, and finally performs spectrum peak detection and timing to estimate whether there is user access, please refer to fig. 4, which is an exemplary diagram of an NR PRACH signal receiving flow in the prior art provided by an embodiment of the present invention.

In the prior art, a ZC sequence forms frequency domain data after DFT, and then zero padding is performed to perform IFFT, and the resulting ZC sequence is converted into a time domain, so that the resulting ZC sequence is interpolated from the original ZC sequence, and the properties of the ZC sequence can be maintained. That is, this procedure requires one time of calculation of DFT, and the ZC sequence adopted by the PRACH is usually a relatively large prime number, so an operation of calculating a prime number long DFT is required, which is generally complex, for example, CZT algorithm, and in order to avoid directly calculating a prime number DFT, it is necessary to use FFT operation to first construct a sequence of power 2, convolve with a ZC sequence of power zero padding to power 2, and then perform fast fourier transform. Therefore, two forward fourier transforms and one inverse fourier transform are required for implementation.

Meanwhile, the radius of the cell of the ground communication system is smaller, so the time delay is not too large usually, in this case, the lengths of the CP and the GT do not need to be too long, so that the user time delay can be ensured to be within the protection of the CP, and all UE signals in the cell can be received by using one receiving window at the receiving end. In an application scenario with a large time delay, such as a low-earth satellite system, the satellite-ground transmission time delay is large, and the cell coverage radius is larger than that of a ground system, the conventional PRACH channel format cannot meet the user timing requirement of a base station, and if the CP length is larger than the transmission time delay, the pilot length is too large, and the frequency interval between pilot subcarriers is too small due to the too large pilot length, which is easily affected by the frequency offset, resulting in detection failure or timing misalignment.

In addition, in the PRACH receiving procedure of LTE/NR, since the transmission delay is within the protection range of the CP, a detection window is adopted, which can not only fully receive all access signals in the cell. However, in an application scenario with a large delay, the transmission delay difference between the central user and the edge user in the cell is also large, and it cannot be ensured that the access signals of all users fall within one window in a CP manner, so the conventional PRACH of LTE/NR cannot be applied to this scenario.

In view of the above problems in the application scenario where the prior art is applicable to a large transmission delay, the inventors provide a new PRACH signal format, and provide a corresponding PRACH signal processing method based on the PRACH signal format, which will be described in detail below.

Taking a low-orbit broadband satellite system as an example, because an application scenario with a large time delay is to be applied, the subcarrier interval of the random access signal is larger than the compensated satellite-to-ground frequency offset, at this time, the length of the preamble sequence is correspondingly shortened, and the situation that the random access time delay is larger than the preamble length may exist, the improved PRACH format is framed in a way that the complete preamble sequence is repeated for multiple times,and a CP (cyclic redundancy check) adding mode is not adopted to protect the Round Trip transmission Delay (RTD) and the channel Delay, the repeated number of the leader sequences depends on the signal-to-noise ratio required by receiving and the coverage condition of a satellite cell, meanwhile, the total length of the random signal is less than the length of a detection window of a base station minus GT, and the GT is required to meet the requirement of being more than the maximum inter-satellite Round Trip transmission Delay possibly caused after ephemeris correction. In addition, since the time delay of PRACH signal of low-orbit broadband satellite system may be larger than the length of single preamble sequence, it cannot be configured as same as NR system

The parameters enable a plurality of users to share the same root sequence, so when the ZC sequence is generated, in the scheme provided by the embodiment of the invention, the ZC sequence is generated without the need of generating

Parameters, but ZC sequences are generated from the root sequence.

Referring to fig. 5, fig. 5 is an exemplary diagram of an improved PRACH channel format according to an embodiment of the present invention, and in fig. 5, an improved PRACH signal is composed of a predetermined number of identical preamble sequences, and no longer includes a CP and a GT.

The improved PRACH channel format does not contain CP and GT any more, so the leader sequence is not limited by the contradiction between the transmission delay and the size of the subcarrier interval any more, and the application scene of larger delay can be supported.

Based on the improved PRACH channel format, an embodiment of the present invention further provides a method for processing an improved PRACH signal by a signal transmitting end, where the method is applied to the signal transmitting end, and fig. 6 is a diagram illustrating a PRACH signal processing flow provided by an embodiment of the present invention, where the method includes the following steps:

and step S100, generating a ZC sequence according to a preset root value.

In this embodiment, the preset root value is also referred to as a preset root sequence, and in this embodiment, each user employs a respective preset root sequence.

Step S110, the ZC sequence is subjected to time domain-frequency domain conversion to obtain a leader sequence.

And step S120, forming the PRACH signals by the preset number of pilot sequences and sending the PRACH signals to a signal receiving end.

In this embodiment, the preset number is predetermined according to the signal-to-noise ratio of the received signal in the actual application scenario and the coverage condition of the satellite cell.

The method provided by the embodiment of the invention generates the ZC sequence according to the preset root value, then performs time-frequency domain conversion on the ZC sequence to obtain the pilot sequence, and finally forms the PRACH signal which accords with the improved PRACH signal format by the pilot sequences with the preset number and sends the PRACH signal to the signal receiving end, thereby providing the signal generation method suitable for the improved PRACH signal format.

On the basis of fig. 6, an embodiment of the present invention further provides a specific method for obtaining a preamble sequence, please refer to fig. 7, fig. 7 is an exemplary diagram of another PRACH signal processing flow provided by the embodiment of the present invention, and step S110 includes the following sub-steps:

sub-step S1101, maps ZC sequences to subcarriers.

And a substep S1102, performing IFFT operation on the subcarriers to obtain a preamble sequence.

In this embodiment, the ZC sequence is directly mapped to the subcarriers, and after performing IFFT operation on the subcarriers, a preamble sequence is obtained, which can be represented by the following formula:

wherein the content of the first and second substances,

transmitting data for the user's frequency domain as a root value

The ZC sequence of (a) to (b),

firstly, toA pilot sequence, k denotes an index value of a ZC sequence, i.e., the kth ZC sequence, N denotes a length of a time domain sequence, N denotes an index of the time domain sequence,

，

is and

root value of the dual.

The specific leader sequence may be demonstrated using the above formula as follows:

suppose that the frequency domain of the user sends data as root

The ZC sequence of (a) to (b),

and then IDFT is performed on it, the time domain signal transmitted by the baseband can be expressed as:

(1)

wherein the content of the first and second substances,

the definition is as follows:

it can be proved that if the frequency domain signal is a ZC sequence, the result after IDFT (1) is not a ZC sequence but is related to the ZC sequence and can be regarded as an equivalent ZC sequence, and the root of the equivalent ZC sequence has a dual relationship with the root of the frequency domain ZC sequence, which is proved as follows:

assuming a transmitted pilot signal

Is a ZC sequence

Inverse Fourier transform of

(2)

Wherein the content of the first and second substances,

satisfy the requirement of

In the formula (2)

(3)

Due to the fact that

Therefore, the temperature of the molten steel is controlled,

wherein

Is a positive integer. (3) First item in the formula

In the above formula, the first and second carbon atoms are,

，

is rooted in

ZC sequence of

。

(3) Second term in the formula

Since ZC sequences have the characteristic of N cycles, the above formula is the sum of ZC sequences, which is a fixed value.

After the above two deductions, the signal is finally sent

Can be expressed in the following forms

(4)

From the formula (4), ZC sequence B

The IDFT of (A) is one with the otherIndividual ZC sequence

Related sequence if

Considered as an equivalent ZC sequence, its root value

Root grafting with original ZC sequence

And (4) dual.

In this embodiment, for better comparison with the prior art, please refer to fig. 8, and fig. 8 is an exemplary diagram of an improved PRACH signaling procedure according to an embodiment of the present invention. In fig. 8, after the ZC sequence is generated, the ZC sequence is directly mapped to subcarriers without performing DFT calculation as in the conventional technique.

In the prior art, because the length of the ZC sequence used by the preamble is generally a prime number, the FFT algorithm of power of 2 cannot be used for DFT operation in the NR system, and additional algorithms and hardware resources are required. The method provided by the embodiment of the invention adopts a mode that the ZC sequence is directly mapped on the frequency domain subcarrier and utilizes the principle that the IDFT of the ZC sequence is another equivalent ZC sequence, thereby omitting the step of generating the DFT of the ZC sequence in the process of generating the PRACH signal, simultaneously saving the extra expense required by the quality-length DFT, saving the computing resource and the hardware resource required by the generation of the PRACH signal and improving the efficiency of generating the PRACH signal.

Based on the above signaling flow, correspondingly, after a signal receiving end receives an improved PRACH signal, in order to perform accurate user access detection based on the improved PRACH signal, an embodiment of the present invention further provides a PRACH signal processing method applied to the signal receiving end, please refer to fig. 9, where fig. 9 is an exemplary diagram of another PRACH signal processing flow provided by the embodiment of the present invention, and the method is applied to the signal receiving end, and includes the following steps:

step S200, receiving a PRACH signal sent by a signal sending end, wherein the PRACH signal consists of a preset number of same pilot sequences, each pilot sequence is obtained by performing time domain-frequency domain conversion on a ZC sequence, and the ZC sequence is generated according to a preset root value.

Step S210, intercepting a plurality of preamble sequences in the PRACH signal according to a position of a preset window, where the position of the preset window includes a current position and a position where sliding is performed for a preset number of times from the current position.

In this embodiment, the length of the preset window may be determined according to the number of preambles in the preamble in the PRACH signal and the length of the preamble, and as a specific implementation manner, in order to make the collected PRACH signal more complete as low as possible, the length of the preset window = (the number of preambles in the PRACH signal + 1) × the length of the preamble is usually preset.

In this embodiment, the preset window performs sliding for a preset number of times, where the preset number of times may be predetermined according to actual needs, for example, the preset number of times is set to 2. Referring to fig. 10, fig. 10 is a diagram illustrating a sliding of a preset window according to an embodiment of the present invention. In fig. 10, if the number of the preamble sequences in the PRACH signal is 3, the length of the preset window is set to the total length of 4 preamble sequences. As can be seen from fig. 10, when the preset window is located at the current position, only the first two complete preamble sequences in the PRACH signal are captured, after the preset window slides for the first time, the first 3 complete preamble sequences in the PRACH signal captured by the preset window are captured, and after the preset window slides for the second time, the last two complete preamble sequences in the PRACH signal captured by the preset window are captured, so that when the preset window is located at the position after the first sliding, the signal is collected most completely, and the PDP value is higher, so that it can be determined that the PRACH signal is completely located in the second sliding window, and thus the time delay of the integral multiple of the preamble can be solved.

Step S220, calculating a PDP value corresponding to each position of the preset window according to the plurality of preamble sequences corresponding to each position of the preset window.

In this embodiment, when the preset window is located at different positions, the number of the captured preamble sequences is different, and a PDP value corresponding to each position of the preset window may be calculated for the preamble sequences captured at each position of the preset window.

In this embodiment, the PDP value is a Power Delay Profile, and the PDP is called Power Delay Profile.

Step S230, detecting whether there is an access signal according to a maximum value of the PDP values corresponding to all positions of the preset window.

In this embodiment, as a specific implementation manner for detecting whether there is an access signal, the detection may be implemented by determining whether the maximum value is greater than a preset threshold, that is, if the maximum value is greater than the preset threshold, it is determined that there is an access signal, and if the maximum value is less than or equal to the preset threshold, it is determined that there is no access signal.

According to the method provided by the embodiment of the invention, the position of the preset window is slid for multiple times, the corresponding PDP value is calculated according to the leader sequences at different positions, and finally whether the access signal exists is detected according to the maximum value in the PDP value, so that the detection of the access signal is more accurate.

On the basis of fig. 9, an embodiment of the present invention further provides a specific implementation manner of calculating a PDP value corresponding to each position of a preset window, please refer to fig. 11, fig. 11 is an exemplary diagram of another PRACH signal processing flow provided by the embodiment of the present invention, and step S220 includes the following sub-steps:

in the substep S2201, any position of the preset window is set as a target position, and a plurality of preamble sequences corresponding to the target position are set as target preamble sequences.

In this embodiment, the PDP value corresponding to any position of the preset window may be calculated by the method described in the substeps S2201 to 2204. The target position is any position of the preset window, the target preamble sequence is a preamble sequence captured when the preset window is at the target position, and the preamble sequence may be multiple.

And a substep S2202, performing frequency domain-time domain conversion on each preamble sequence in the target preamble sequence to obtain a time domain related sequence of each preamble sequence.

In this embodiment, the frequency-domain-to-time-domain conversion is actually the inverse conversion flow of the time-domain-to-frequency-domain conversion described above. As a specific embodiment, the following method may be adopted for performing the frequency domain-time domain conversion:

firstly, any preamble sequence in the target preamble sequence is used as a preamble sequence to be processed.

And secondly, performing FFT operation on the pilot sequence to be processed, and then performing subcarrier demapping to obtain subcarrier frequency domain data.

In this embodiment, the FFT operation and the IFFT operation are inverse operations, and the subcarrier mapping and the subcarrier demapping are inverse processing flows.

And thirdly, carrying out conjugate multiplication on the subcarrier frequency domain data and the preset reference ZC sequence to obtain a multiplication result.

And fourthly, carrying out IDFT calculation on the multiplication result to obtain a time domain correlation sequence of the pilot sequence to be processed.

And a substep S2203, overlapping the plurality of time domain correlation sequences of the target preamble sequence to obtain a target correlation sequence.

In sub-step S2204, a PDP value corresponding to the target position is calculated based on the main peak having the largest peak value in the target correlation sequence.

In this embodiment, a peak with the largest peak value in the target correlation sequence is called a main peak, and as an implementation manner for specifically calculating a PDP value corresponding to a target position, the following method may be adopted:

first, the former peak and the latter peak adjacent to the main peak are taken as the secondary peaks.

And secondly, combining the peak value of the main peak and the peak value of the secondary peak to obtain a PDP value corresponding to the target position.

In the embodiment, because the main peak and the secondary peak are considered simultaneously, the pilot sequence energy can be collected as much as possible, and the access signal can be better detected than the main peak value is detected independently. Referring to fig. 12, fig. 12 is a diagram illustrating three-peak combining according to an embodiment of the present invention.

In this embodiment, in order to better support the calculation process of the PDP, the embodiment of the present invention further provides a calculation formula of the PDP and a derivation process of the calculation formula, where the derivation process is as follows:

the signal received by the signal receiving terminal

Is that the user sends PRACH signal

Through superposition of a channel, frequency offset and noise:

wherein

For the channel coefficients of the l-th multipath,

is the time delay of the first multipath, L is the number of the multipath,

frequency offset for signals

Wherein

In order to be able to sample the rate,

for the purpose of frequency offset,

is a mean of 0 and a variance of

N is the index of the time domain sequence, N is the length of the time domain sequence, j is the imaginary part indicator

，

The time domain transmission signal is represented by equation (4). In the random access channel, because the symbol period of the random access signal is designed to be longer and much longer than the multipath delay, the multipath can be regarded as only one path, and the received signal is rewritten as follows:

wherein the content of the first and second substances,

is an invariant value, and is ignored in subsequent derivation

，

Substituting the transmitted signal for user delay

To obtain

Wherein the content of the first and second substances,

is a root value, and is rooted with the original ZC sequence of the signal sending end

And (4) dual. After the received signal is obtained, FFT operation is carried out, N effective data values in the frequency domain resource corresponding to the PRACH are obtained through sub-carrier demapping, and assuming that the influence of frequency offset, time delay and a channel is not considered, the value on the k sub-carrier is as follows

，

Wherein the content of the first and second substances,

is the value on the k-th sub-carrier,

in the case of frequency-domain noise,

is the original ZC sequence.

At a receiving end, the FFT data is multiplied by the local reference signal in a conjugate mode, and then IDFT is carried out to form a time domain correlation sequence

Can prove that

Frequency domain computing method of

Equivalent to time domain calculation formula as follows

In the above equation, it is assumed that the delay is ignored

Taking into account only frequency deviation

Related sequences

Can be expressed as:

due to the fact that

Sum of variance of

Is fixed, and therefore

The value of (A) depends on the first term, the noise term can be ignored, have

Proposing an item independent of n

In the above formula

The absolute value of (a) is a fixed value, wherein,

is a sub-carrier spacing of the carrier,

is the time length of the preamble sequence. When in use

In m satisfying the following formula,

maximum value of

Due to the fact that

The relationship of the period is m satisfying the following relationship

Generating a maximum value

Due to the fact that

M is an integer value, so that m satisfies

When the temperature of the water is higher than the set temperature,

there is a maximum value. Meanwhile, the frequency deviation causes the occurrence of secondary peakThe secondary peak appears in

M of (1).

When the receiving end detects the user, it is assumed that other smaller secondary peaks are ignored, the values of the corresponding main peak and the left and right secondary peaks are accumulated, and then whether the values exceed the threshold or not is judged, so that the sequence energy can be collected as much as possible, and the user can be better detected than the user can be detected by singly detecting the main peak. This method of accumulation with three peaks is called the three-peak detection method. The method is a more effective method than single peak detection when performing autocorrelation detection on a ZC sequence affected by frequency deviation. The PDP for the trimodal detection method is calculated as:

wherein the content of the first and second substances,

，

is the peak value of the main peak, and the peak value of the main peak,

a secondary peak value of a previous peak adjacent to the main peak,

is the secondary peak value of the latter peak adjacent to the main peak.

In this embodiment, for better comparison with the prior art, please refer to fig. 13, where fig. 13 is an exemplary diagram of an improved PRACH signal reception procedure according to an embodiment of the present invention. In fig. 13, the spectral peak search at the current position corresponds to the calculation of the PDP value at the current position in the method, the spectral peak search at the position after each sliding corresponds to the calculation of the PDP value at the position after each sliding in the method, the maximum spectral peak is searched for a plurality of times and corresponds to the maximum value in the PDP values determined in the method, and the access signal detection is performed according to the maximum spectral peak and corresponds to the method according to the maximum value.

In order to more clearly illustrate the detection method of the sliding preset window, the embodiment of the present invention provides a specific simulation analysis process, and the simulation parameters are set as follows: the low-orbit satellite system adopts Ka wave band, and the subcarrier interval of PRACH channel is 10 kHz. The root of the ZC sequence is 240. mu. and 839 in length. The Doppler frequency offset of the PRACH signal in the simulation is 0.3 times of the subcarrier interval, and the signal-to-noise ratio of the PRACH signal is-5 dB. The format of the PRACH signal is composed of two pilot sequences, and the position of the transmission time is the length of one pilot sequence plus 20 sampling points.

Referring to fig. 14(a), fig. 14(b) and fig. 14(c) again, fig. 14(a), fig. 14(b) and fig. 14(c) are exemplary diagrams of PDPs with preset window positions after the first sliding window, the second sliding window and the third sliding window, respectively, and the PDPs with preset windows at these three positions are 0.47, 0.94 and 0.43, respectively. As can be seen from the three PDP values, the peak value at the second position is larger than the first and third sliding windows, indicating that the signal is within the predetermined window at the second position, and therefore the signal delay is a pilot length plus 20, which is the same as the actual position of the transmitted signal. In addition, in the exemplary PDP of the second sliding window in fig. 14(b), due to the existence of frequency offset, a secondary peak appears in the correlation peak, the main peak is at the position of 20, the left and right secondary peaks are at the positions of 619 and 260, respectively, and the distance from the main peak is 240 (equal to that of the main peak)

Value) consistent with a theoretically derived peak relationship. Meanwhile, the value of the left side secondary peak is larger than that of the right side secondary peak, and the positive and negative directions of the frequency deviation are indicated.

Referring to fig. 15, fig. 15 is a detection probability diagram of an access signal according to an embodiment of the present invention, where a main peak is decreased and an auxiliary peak is increased due to the existence of frequency offset, so that a three-peak joint detection method is adopted in detection, that is, a main peak and two auxiliary peaks around the main peak are combined to determine whether an access signal exists. As can be seen from the simulation, the PRACH format proposed by the embodiment of the present invention can effectively detect the user access signal at a low signal-to-noise ratio.

In the method provided by the embodiment of the invention, the plurality of preamble sequences of the preset window at the target position are subjected to frequency domain-time domain conversion, the time domain related sequences corresponding to the plurality of preamble sequences are superposed to obtain the target related sequence, and the corresponding PDP value is calculated based on the main peak in the target related sequence.

In order to perform the corresponding steps applied to the signal transmitting end in the foregoing embodiments and various possible implementations, an implementation manner of the first PRACH signal processing apparatus 100 is given below. Referring to fig. 16, fig. 16 is a block diagram illustrating a first PRACH signal processing apparatus 100 according to an embodiment of the present invention. The first PRACH signal processing apparatus 100 is applied to a signal transmitting end, and it should be noted that the basic principle and the generated technical effects of the first PRACH signal processing apparatus 100 provided in this embodiment are the same as those of the above embodiments, and for the sake of brief description, no reference is made in this embodiment.

The first PRACH signal processing apparatus 100 includes a signal generating module 110 and a transmitting module 120.

And a signal generating module 110, configured to generate a ZC sequence according to a preset root value, and perform time-frequency domain conversion on the ZC sequence to obtain a preamble sequence.

The sending module 120 is configured to combine the preset number of pilot sequences into a PRACH signal and send the PRACH signal to a signal receiving end.

As a specific implementation manner, the signal generating module 110 is specifically configured to: mapping a ZC sequence to a subcarrier; and performing IFFT operation on the subcarriers to obtain a pilot sequence.

In order to perform the corresponding steps applied to the signal receiving end in the foregoing embodiments and various possible embodiments, an implementation manner of the second PRACH signal processing apparatus 200 is given below. Referring to fig. 17, fig. 17 is a block diagram illustrating a second PRACH signal processing apparatus 200 according to an embodiment of the present invention. It should be noted that the basic principle and the technical effects of the second PRACH signal processing apparatus 200 provided in this embodiment are the same as those of the above-mentioned embodiments, and for the sake of brief description, no reference is made in this embodiment.

The second PRACH signal processing apparatus 200 includes a receiving module 210, a processing module 220, and a detecting module 230.

A receiving module 210, configured to receive a PRACH signal sent by a signal sending end, where the PRACH signal is composed of a preset number of identical preamble sequences, each of the preamble sequences is obtained by performing time-frequency domain conversion on a ZC sequence, and the ZC sequence is generated according to a preset root value.

A processing module 220 for: intercepting a plurality of pilot sequences in the PRACH signal according to the position of a preset window, wherein the position of the preset window comprises the current position and the position of each sliding when sliding for a preset number of times from the current position; and calculating a PDP value corresponding to each position of the preset window according to the plurality of leader sequences corresponding to each position of the preset window.

As a specific implementation manner, the processing module 220 is specifically configured to: taking any position of a preset window as a target position, and taking a plurality of pilot sequences corresponding to the target position as target pilot sequences; performing frequency domain-time domain conversion on each pilot sequence in the target pilot sequence to obtain a time domain related sequence of each pilot sequence; superposing a plurality of time domain related sequences of a target pilot sequence to obtain a target related sequence; and calculating a PDP value corresponding to the target position according to the main peak with the maximum peak value in the target correlation sequence.

As a specific implementation manner, when performing frequency-domain to time-domain conversion on each preamble sequence in the target preamble sequence to obtain a time-domain correlation sequence of each preamble sequence, the processing module 220 is specifically configured to: taking any leader sequence in the target leader sequence as a leader sequence to be processed; performing FFT operation on a pilot sequence to be processed, and then performing subcarrier demapping to obtain subcarrier frequency domain data; carrying out conjugate multiplication on the subcarrier frequency domain data and a preset reference ZC sequence to obtain a multiplication result; and performing IDFT calculation on the multiplication result to obtain a time domain correlation sequence of the pilot sequence to be processed.

As a specific embodiment, when the processing module 220 calculates the PDP value corresponding to the target position according to the main peak with the maximum peak value in the target correlation sequence, it is specifically configured to: taking the former peak and the latter peak adjacent to the main peak as secondary peaks; and combining the peak value of the main peak and the peak value of the secondary peak to obtain a PDP value corresponding to the target position.

The detecting module 230 is configured to detect whether there is an access signal according to a maximum value of the PDP values corresponding to all positions of the preset window.

Referring to fig. 18, fig. 18 shows a block schematic diagram of the communication device 10 according to the embodiment of the present invention, where the communication device 10 includes a processor 11, a memory 12, a bus 13, and a communication interface 14. The processor 11 and the memory 12 are connected by a bus 13, and the processor 11 communicates with an external device via a communication interface 14.

The processor 11 may be an integrated circuit chip having signal processing capabilities. In implementation, the steps of the above method may be performed by integrated logic circuits of hardware or instructions in the form of software in the processor 11. The Processor 11 may be a general-purpose Processor, and includes a Central Processing Unit (CPU), a Network Processor (NP), and the like; but may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components.

The memory 12 is used for storing a program, for example, the first PRACH signal processing apparatus 100 or the second PRACH signal processing apparatus 200 in the embodiment of the present invention, and each of the first PRACH signal processing apparatus 100 or the second PRACH signal processing apparatus 200 includes at least one software functional module which may be stored in the memory 12 in a form of software or firmware (firmware), and the processor 11 executes the program after receiving an execution instruction to implement the PRACH signal processing method applied to the signal transmitting end or the PRACH signal processing method applied to the signal receiving end in the embodiment of the present invention.

The Memory 12 may include a high-speed Random Access Memory (RAM) and may also include a non-volatile Memory (non-volatile Memory). Alternatively, the memory 12 may be a storage device built in the processor 11, or may be a storage device independent of the processor 11.

The bus 13 may be an ISA bus, a PCI bus, an EISA bus, or the like. Fig. 18 is represented by only one double-headed arrow, but does not represent only one bus or one type of bus.

An embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the PRACH signal processing method applied to a signal transmitting end or the PRACH signal processing method applied to a signal receiving end as described above.

In summary, embodiments of the present invention provide a PRACH signal processing method, an apparatus, a communication device, and a storage medium, where the PRACH signal processing method applied to a signal receiving end includes: receiving a PRACH signal sent by a signal sending end, wherein the PRACH signal consists of a preset number of identical pilot sequences, each pilot sequence is obtained by carrying out time domain-frequency domain conversion on a ZC sequence, and the ZC sequence is generated according to a preset root value; intercepting a plurality of pilot sequences in the PRACH signal according to the position of a preset window, wherein the position of the preset window comprises the current position and the position of each sliding when sliding for a preset number of times from the current position; calculating a PDP value corresponding to each position of a preset window according to a plurality of leader sequences corresponding to each position of the preset window; and detecting whether an access signal exists according to the maximum value in the PDP values corresponding to all the positions of the preset window. Compared with the prior art, the embodiment of the invention adopts a brand-new PRACH signal format, the PRACH signal format consists of the same pilot sequences with the preset number, and the PRACH signal format does not have CP, so the pilot sequences are not limited by contradictions between transmission delay and subcarrier interval size, and meanwhile, the PRACH signal received by a signal receiving end corresponding to each sliding position of a sliding window is processed by utilizing a sliding window mode to obtain a corresponding PDP value, and the accurate detection of an access signal is realized according to the PDP value.

The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.

Claims

1. A PRACH signal processing method is applied to a signal receiving end which is in communication connection with a signal sending end, and the method comprises the following steps:

receiving a Physical Random Access Channel (PRACH) signal sent by the signal sending end, wherein the PRACH signal consists of a preset number of same pilot sequences and does not comprise a Cyclic Prefix (CP) and a Guard Time (GT), each pilot sequence is obtained by performing time domain-frequency domain conversion on a ZC sequence, and the ZC sequence is generated according to a preset root value;

intercepting a plurality of pilot sequences in the PRACH signal according to the position of a preset window, wherein the position of the preset window comprises the current position and the position of each sliding when sliding for a preset number of times from the current position;

taking any position of the preset window as a target position, and taking the plurality of preamble sequences corresponding to the target position as target preamble sequences;

performing frequency domain-time domain conversion on each pilot sequence in the target pilot sequence to obtain a time domain related sequence of each pilot sequence;

superposing the plurality of time domain related sequences of the target pilot sequence to obtain a target related sequence;

calculating a power time delay spectrum (PDP) value corresponding to the target position according to the main peak with the maximum peak value in the target correlation sequence;

and detecting whether an access signal exists according to the maximum value in the PDP values corresponding to all the positions of the preset window.

2. The method for processing the PRACH signal according to claim 1, wherein the step of performing frequency-domain to time-domain conversion on each of the target preamble sequences to obtain a time-domain correlation sequence of each of the preamble sequences comprises:

taking any one of the target preamble sequences as a preamble sequence to be processed;

performing FFT operation on the pilot sequence to be processed, and then performing subcarrier demapping to obtain subcarrier frequency domain data;

carrying out conjugate multiplication on the subcarrier frequency domain data and a preset reference ZC sequence to obtain a multiplication result;

and carrying out IDFT calculation on the multiplication result to obtain a time domain correlation sequence of the pilot sequence to be processed.

3. The method for processing the PRACH signal according to claim 1, wherein the step of calculating the PDP value corresponding to the target location according to the main peak with the largest peak value in the target correlation sequence includes:

taking a former peak and a latter peak adjacent to the main peak as secondary peaks;

and combining the peak value of the main peak and the peak value of the secondary peak to obtain a PDP value corresponding to the target position.

4. A PRACH signal processing method is applied to a signal sending end, wherein the signal sending end is in communication connection with a signal receiving end, and the method comprises the following steps:

generating a ZC sequence according to a preset root value;

carrying out time domain-frequency domain conversion on the ZC sequence to obtain a pilot sequence;

forming a Physical Random Access Channel (PRACH) signal by a preset number of pilot sequences and sending the PRACH signal to the signal receiving end so that the PRACH information is processed by the signal receiving end in the following way: intercepting a plurality of pilot sequences in the PRACH signal according to the position of a preset window, wherein the PRACH signal does not comprise a Cyclic Prefix (CP) and a Guard Time (GT), and the position of the preset window comprises the current position and the position of each sliding when sliding for a preset number of times from the current position; taking any position of the preset window as a target position, and taking the plurality of preamble sequences corresponding to the target position as target preamble sequences; performing frequency domain-time domain conversion on each pilot sequence in the target pilot sequence to obtain a time domain related sequence of each pilot sequence; superposing the plurality of time domain related sequences of the target pilot sequence to obtain a target related sequence; calculating a power time delay spectrum (PDP) value corresponding to the target position according to the main peak with the maximum peak value in the target correlation sequence; and detecting whether an access signal exists according to the maximum value in the PDP values corresponding to all the positions of the preset window.

5. The method for processing the PRACH signal according to claim 4, wherein the step of performing the time-frequency domain conversion on the ZC sequence to obtain a preamble comprises:

mapping the ZC sequence to subcarriers;

and performing IFFT operation on the subcarriers to obtain a pilot sequence.

6. A PRACH signal processing apparatus, which is applied to a signal receiving end, where the signal receiving end is in communication connection with a signal transmitting end, and the apparatus includes:

a receiving module, configured to receive a PRACH signal, which is a physical random access channel and is sent by the signal sending end, where the PRACH signal is composed of a preset number of identical preamble sequences, and does not include a cyclic prefix CP and a guard time GT, each of the preamble sequences is obtained by performing time-frequency domain conversion on a ZC sequence, and the ZC sequence is generated according to a preset root;

a processing module, configured to intercept multiple preamble sequences in the PRACH signal according to a position of a preset window, where the position of the preset window includes a current position and a position where sliding is performed for a preset number of times from the current position;

a processing module further configured to: taking any position of the preset window as a target position, and taking the plurality of preamble sequences corresponding to the target position as target preamble sequences; performing frequency domain-time domain conversion on each pilot sequence in the target pilot sequence to obtain a time domain related sequence of each pilot sequence; superposing the plurality of time domain related sequences of the target pilot sequence to obtain a target related sequence; calculating a power time delay spectrum (PDP) value corresponding to the target position according to the main peak with the maximum peak value in the target correlation sequence;

and the detection module detects whether an access signal exists according to the maximum value in the PDP values corresponding to all the positions of the preset window.

7. The PRACH signal processing device is applied to a signal sending end, wherein the signal sending end is in communication connection with a signal receiving end, and the device comprises:

the signal generation module is used for generating a ZC sequence according to a preset root value;

the signal generation module is used for carrying out time domain-frequency domain conversion on the ZC sequence to obtain a pilot sequence;

a sending module, configured to form a physical random access channel PRACH signal with a preset number of pilot sequences and send the PRACH signal to the signal receiving end, so that the signal receiving end processes PRACH information in the following manner: intercepting a plurality of pilot sequences in the PRACH signal according to the position of a preset window, wherein the PRACH signal does not comprise a Cyclic Prefix (CP) and a Guard Time (GT), and the position of the preset window comprises the current position and the position of each sliding when sliding for a preset number of times from the current position; taking any position of the preset window as a target position, and taking the plurality of preamble sequences corresponding to the target position as target preamble sequences; performing frequency domain-time domain conversion on each pilot sequence in the target pilot sequence to obtain a time domain related sequence of each pilot sequence; superposing the plurality of time domain related sequences of the target pilot sequence to obtain a target related sequence; calculating a power time delay spectrum (PDP) value corresponding to the target position according to the main peak with the maximum peak value in the target correlation sequence; and detecting whether an access signal exists according to the maximum value in the PDP values corresponding to all the positions of the preset window.

8. A communication device comprising a memory and a processor, wherein the memory stores a computer program which, when executed by the processor, implements the PRACH signal processing method according to any one of claims 1-3, or implements the PRACH signal processing method according to any one of claims 4-5.

9. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the PRACH signal processing method according to any one of claims 1-3, or carries out the PRACH signal processing method according to any one of claims 4-5.