CN105992385B - Physical random access channel signal generation method - Google Patents
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Abstract
The invention relates to a physical random access channel signal generation method, which comprises the following steps: receiving a random access channel parameter and a leader sequence parameter sent by a base station; calculating the offset of the central frequency point by using the random access channel parameters; reducing the first sampling frequency of the digital-to-analog conversion chip to a second sampling frequency; generating a ZC sequence by using the leader sequence parameters, and performing discrete Fourier transform operation on the ZC sequence to obtain a frequency domain signal; according to the second sampling frequency, performing fast Fourier inverse transformation operation on the frequency domain signal to obtain a time domain signal; adjusting the first central frequency point of the radio frequency chip to a second central frequency point according to the central frequency point offset; and sending the time domain signal according to the second central frequency point. The method provided by the application greatly reduces the operation amount, processing time delay and data cache generated by the PRACH signal by directly reducing the sampling frequency and adjusting the central frequency point according to the signal characteristics of the PRACH, and is simple and efficient.
Description
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a method and an apparatus for generating a Physical Random Access Channel (PRACH) signal in a Long Term Evolution (LTE) system.
Background
In the random access process of the LTE system, a terminal is required to complete the generation of a preamble sequence and a baseband signal. According to protocol specifications, the generation of analog baseband signals can be seen as two parts: ZC (Zadoff-chu) sequence length point Discrete Fourier Transform (DFT) of a preamble sequence and Inverse Fast Fourier Transform (IFFT) of a time period point of the preamble sequence. For example, under 20M bandwidth, the length of the preamble sequence with a preamble format of zero is 24576, and the PRACH signal generation needs 24576-point IFFT at most, which greatly increases the operation complexity and data buffer space. The bandwidth occupied by the PRACH signal in the frequency domain is only 6 Physical Resource Blocks (PRBs), after the DFT of the PRACH signal frequency domain data is completed, 0 needs to be supplemented to the whole bandwidth, and then the processing of the multipoint IFFT is completed, which is a waste from the perspective of data storage and complex operation.
In the prior art, the IFFT length is reduced by means of up-sampling frequency and frequency offset compensation, although the calculation amount of the long IFFT is reduced, the requirements of real-time performance and power consumption are difficult to meet, and the interpolation and phase adjustment which are performed later take a long time. Without the fast algorithm of interpolation and phase adjustment, the time saved by a short IFFT is not enough to offset the time overhead of interpolation.
Disclosure of Invention
The purpose of the application is to provide a physical random access channel signal generation method, which solves the problems of large data calculation amount, long processing time and large occupied storage space in the signal generation process of the PRACH channel by combining the direct reduction of the sampling frequency and the adjustment of the central frequency point.
In order to achieve the above object, the present application provides a method for generating a physical random access channel signal, the method comprising:
receiving a random access channel parameter and a leader sequence parameter sent by a base station;
calculating the offset of the central frequency point by using the random access channel parameters;
reducing the first sampling frequency of the digital-to-analog conversion chip to a second sampling frequency;
generating a ZC sequence by using the leader sequence parameters, and performing discrete Fourier transform operation on the ZC sequence to obtain a frequency domain signal;
according to the second sampling frequency, performing fast Fourier inverse transformation operation on the frequency domain signal to obtain a time domain signal;
adjusting the first central frequency point of the radio frequency chip to a second central frequency point according to the central frequency point offset;
and sending the time domain signal according to the second central frequency point.
The physical random access channel signal generation method provided by the application greatly reduces the calculation amount, processing time delay and data cache generated by the PRACH channel signal by directly reducing the sampling frequency and adjusting the central frequency point aiming at the signal characteristics of the PRACH channel, and is simple and efficient.
Drawings
Fig. 1 is a flowchart of a method for generating a physical random access channel signal according to an embodiment of the present disclosure.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. 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 application.
Fig. 1 is a flowchart of a method for generating a physical random access channel signal according to an embodiment of the present disclosure. As shown in fig. 1, the main execution body of the method is a wireless communication device, and the method specifically includes:
step 101, receiving a random access channel parameter and a preamble sequence parameter sent by a base station.
Specifically, the device receives a random access channel parameter and a preamble sequence parameter transmitted by a base station. Random access channel parameters such as subcarrier spacing Δ f, first physical resource block number occupied by PRACH resourceNumber of subcarriers of one resource block in frequency domainNumber of uplink resource blocksPreamble sequence parameters, e.g. ZC sequence length Nzc。
Optionally, after receiving the random access channel parameter and the preamble sequence parameter sent by the base station, the method further includes:
and recording a first central frequency point of the radio frequency chip, a first filter bandwidth and a first sampling frequency of the digital-to-analog conversion chip.
And 102, calculating the offset of the central frequency point by using the random access channel parameters.
Specifically, a formula is calculated according to the offset of the central frequency point
Calculating to obtain the offset of the central frequency point, wherein delta f is the interval of the sub-carriers,the first physical resource block number occupied by PRACH resources,for the number of subcarriers of one resource block in the frequency domain,is the number of uplink resource blocks.
And 103, reducing the first sampling frequency of the digital-to-analog conversion chip to a second sampling frequency.
Specifically, the first sampling frequency of the digital-to-analog conversion chip recorded in step 101 is reduced to 1/N times of the original sampling frequency, so as to obtain a second sampling frequency, where N is determined according to the processing capability of the device.
After the reducing the first sampling frequency of the digital-to-analog conversion chip to the second sampling frequency, the method further comprises:
and reducing the bandwidth of the first filter to 1/N times of the original bandwidth of the first filter to obtain the bandwidth of a second filter, wherein N is determined according to the processing capacity of the equipment.
And 104, generating a ZC sequence by using the leader sequence parameters, and performing discrete Fourier transform operation on the ZC sequence to obtain a frequency domain signal.
Specifically, a formula is calculated according to a ZC sequenceCalculating to obtain a ZC sequence, wherein xu(N) is the u-th root ZC sequence, NzcIs the ZC sequence length.
And carrying out discrete Fourier transform operation on the ZC sequence to obtain a frequency domain signal derivation process as follows:
without taking into account the time delay and the amplitude scaling factor betaPRACHIn this case, the discrete time domain representation of the preamble baseband signal:
wherein N iszcIs the length of ZC sequence, xu,v(n) a ZC sequence with a root sequence number u and a cyclic shift of v,NSEQis the number of samples of the preamble sequence, Δ fRASubcarrier spacing, T, for random access preamblesFor the sampling interval of the preamble sequence, TSEQTime period of preamble sequence, fsFor the sampling frequency, n0＝φ+K(k0+1/2)，n0Is at NSEQThe frequency domain position on the point sampling point, phi is a fixed offset used for determining the frequency domain position of the access preamble sequence in the physical resource block, K is the subcarrier interval of the uplink data transmission/the subcarrier interval of the random access preamble, the first physical resource block number occupied by PRACH resources,for the number of subcarriers of one resource block in the frequency domain,is as followsNumber of line resource blocks.
xu,v(n) is obtained by DFT:then s (m) can be expressed as:
due to Xu,v(k) Sequence length NZCLess than NSEQTaking preamble format 0 as an example, NZC＝839,NSEQ24576, mixing Xu,v(k) The sequence is calculated from the previous parameters at the frequency domain position n0Mapping to length NSEQNovel sequencesAbove, the rest are not Xu,v(k) The position occupied by the carbon fiber is added with 0,the expression is as follows:
then s (m) can be expressed as:
wherein Xu,v(k) The derivation of (c) is as follows:
by decomposition and combination of Xu(k) Can be expressed as:
wherein u is-1Representing u modulo NZCMultiplication afterInverse element, u-1The table can be made in advance and the table look-up mode is adopted.
Will u-1k is to be regarded as an independent variable,can be expressed as:
n + u-1k is to be regarded as a whole,can be expressed as:
from the cyclic nature of the ZC sequence, it can be derived:
can be seen as a root ZC sequence xuA direct current component of (n). In the real-time signal processing, the direct current component values of the ZC sequences corresponding to different u values can be calculated in advance, and the execution of the whole algorithm can be accelerated in a table look-up mode.
Finally, the DFT of the ZC base sequence can be written as:
Xu(k)＝xu *(u-1k)·Xu(0)
for the cyclic shift related parameter v, the final sequence form is:
xu,v(n)＝xu((n+Cv)mod NZC)
from the cyclic nature of the sequence, it can be derived:
mixing Xu(k) Substituting the above formula, one can obtain:
Xu,v(k)＝(Yu,v(k))*·Xu(0)
only need to find Yu,v(k) And Xu(0) Conjugate multiplication is carried out.
Wherein δ is (u)-1k)(u-1k+1)+2Cvk)/(2NZC)，θ＝δ/2。
And 105, performing fast Fourier inverse transformation operation on the frequency domain signal according to the second sampling frequency to obtain a time domain signal.
Specifically, the IFFT of the PRACH signal corresponding to the first sampling frequency is an I point, where I is TSEQ/TsAfter N times of down-sampling, according to the second sampling frequency, the X obtained in step 104 is processedu,v(k) IFFT operation is performed at I' ═ I/N points to obtain a time domain signal.
And 106, adjusting the first central frequency point of the radio frequency chip to a second central frequency point according to the central frequency point offset.
Specifically, the initial central frequency point of the radio frequency chip is adjusted according to the central frequency point offset calculated in step 102 to obtain a second central frequency point.
And step 107, sending the time domain signal according to the second central frequency point.
Specifically, the time domain signal is sent to the base station in the uplink transmission subframe according to the second filter bandwidth, the second sampling frequency and the second center frequency point.
Optionally, after the sending the time-domain signal according to the second central frequency point, the method further includes:
adjusting the second center frequency point to the first center frequency point;
adjusting the second filter bandwidth to the first filter bandwidth;
adjusting the second sampling frequency to the first sampling frequency.
The physical random access channel signal generation method provided by the application greatly reduces the calculation amount, processing time delay and data cache generated by the PRACH channel signal by directly reducing the sampling frequency and adjusting the central frequency point aiming at the signal characteristics of the PRACH channel, and is simple and efficient.
Those of skill would further appreciate that the various illustrative objects and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied in hardware, a software module executed by a processor, or a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
The above-mentioned embodiments, objects, technical solutions and advantages of the present application are described in further detail, it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present application, and are not intended to limit the scope of the present application, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present application should be included in the scope of the present application.
Claims (3)
1. A method for generating a physical random access channel signal, the method comprising:
receiving a random access channel parameter and a leader sequence parameter sent by a base station; recording a first central frequency point of a radio frequency chip, a first filter bandwidth and a first sampling frequency of a digital-to-analog conversion chip;
calculating the offset of the central frequency point by using the random access channel parameters; particularly, a formula is calculated according to the offset of the central frequency pointCalculating to obtain the offset of the central frequency point, wherein delta f is the interval of the sub-carriers,the first physical resource block number occupied by PRACH resources,for the number of subcarriers of one resource block in the frequency domain,the number of uplink resource blocks;
reducing the first sampling frequency of the digital-to-analog conversion chip to a second sampling frequency; reducing the first filter bandwidth to a second filter bandwidth;
generating a ZC sequence by using the leader sequence parameters, and performing discrete Fourier transform operation on the ZC sequence to obtain a frequency domain signal;
according to the second sampling frequency, performing fast Fourier inverse transformation operation on the frequency domain signal to obtain a time domain signal;
adjusting the first central frequency point of the radio frequency chip to a second central frequency point according to the central frequency point offset;
sending the time domain signal according to the second central frequency point;
adjusting the second center frequency point to the first center frequency point;
adjusting the second filter bandwidth to the first filter bandwidth;
adjusting the second sampling frequency to the first sampling frequency.
2. The method according to claim 1, wherein the generating the ZC sequence using the preamble sequence parameters is specifically:
according to ZC sequence calculation formula0≤n≤NZC-1, calculating a ZC sequence, wherein xu(N) is the u-th root ZC sequence, NzcIs the ZC sequence length.
3. The method of claim 1, wherein the sending the time domain signal to the base station by using the adjusted rf chip specifically comprises:
and sending the time domain signal to a base station by using the adjusted radio frequency chip according to the second filter bandwidth and the second sampling frequency.
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| CN105992385B (en) * | 2015-02-12 | 2019-12-31 | 苏州简约纳电子有限公司 | Physical random access channel signal generation method |
| US11044757B2 (en) * | 2017-10-09 | 2021-06-22 | Qualcomm Incorporated | Carrier-dependent random access channel (RACH) response search space |
| WO2019139426A1 (en) | 2018-01-11 | 2019-07-18 | Samsung Electronics Co., Ltd. | Method of determining frequency-domain offset parameter, user equipment (ue), random access method, method for configuring random access information, corresponding device and computer readable medium |
| CN110062472B (en) * | 2018-01-19 | 2022-11-04 | 北京三星通信技术研究有限公司 | Frequency domain offset parameter determination method, user equipment and computer readable medium |
| US10966172B2 (en) * | 2018-07-09 | 2021-03-30 | Qualcomm Incorporated | Physical random access channel (PRACH) configuration periodicity extension for backhaul links |
| US20220191947A1 (en) * | 2019-03-28 | 2022-06-16 | Panasonic Intellectual Property Corporation Of America | Transmission device, reception device, transmission method, and reception method |
| CN111835434B (en) * | 2019-04-19 | 2022-07-05 | 深圳市鼎阳科技股份有限公司 | Method and device for measuring broadband frequency response |
| CN112584542B (en) * | 2020-12-10 | 2022-07-12 | 紫光展锐(重庆)科技有限公司 | Signal generation method, device, apparatus and storage medium |
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| CN101860395A (en) * | 2010-05-31 | 2010-10-13 | 合肥东芯通信股份有限公司 | Method and equipment for generating preamble sequence |
| CN103516500A (en) * | 2012-06-29 | 2014-01-15 | 联芯科技有限公司 | Generation method and device for physical random accessing channel baseband signal |
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