CN109168186B - Method for searching frequency point in LTE system - Google Patents

Method for searching frequency point in LTE system Download PDF

Info

Publication number
CN109168186B
CN109168186B CN201810980471.1A CN201810980471A CN109168186B CN 109168186 B CN109168186 B CN 109168186B CN 201810980471 A CN201810980471 A CN 201810980471A CN 109168186 B CN109168186 B CN 109168186B
Authority
CN
China
Prior art keywords
frequency
sequence
offset
data block
frequency point
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201810980471.1A
Other languages
Chinese (zh)
Other versions
CN109168186A (en
Inventor
章恩友
龙翔林
蒋卫平
曹小松
陆聪沛
张军强
沈叶
姚晓峰
余浩锋
许智景
林铁树
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ningbo Jianan Electronics Co ltd
Original Assignee
Ningbo Jianan Electronics Co ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ningbo Jianan Electronics Co ltd filed Critical Ningbo Jianan Electronics Co ltd
Priority to CN201810980471.1A priority Critical patent/CN109168186B/en
Publication of CN109168186A publication Critical patent/CN109168186A/en
Application granted granted Critical
Publication of CN109168186B publication Critical patent/CN109168186B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/16—Discovering, processing access restriction or access information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H04L2027/0024—Carrier regulation at the receiver end
    • H04L2027/0026—Correction of carrier offset
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Abstract

A method for realizing fast frequency point search in an LTE system. The invention carries out pre-frequency deviation on the local PSS sequence to ensure that the local PSS sequence is aligned with the received signal in the frequency domain, thereby solving the problem of poor network searching performance caused by inherent frequency deviation caused by frequency point misalignment. The traditional 3 times of calculation related to sliding is changed into 1 time of calculation, the searching performance is improved, and the problems of slow network searching and large power consumption caused by long time required by the adjacent frequency point attempt due to wide LTE bandwidth are solved.

Description

Method for searching frequency point in LTE system
Technical Field
The invention belongs to the field of mobile communication, and particularly relates to a terminal frequency point searching method of an LTE (Long term evolution) system.
Background
An LTE terminal generally needs to go through three phases before accessing a cell: a scanning frequency point stage, a synchronization signal (PSS and SSS) detection process and a Physical Broadcast Channel (PBCH) decoding process. After the above three phases are completed, the terminal determines the resources allocated to the user to communicate with the base station (eNodeB) according to the synchronization information and the broadcast information.
In the stage of scanning frequency points, a frequency band to be scanned is acquired through high-level configuration, scanning of initial frequency points is performed, frequency points (EARFCNs) where cells may exist are found, the interval of the EARFCNs is 100KHz according to the 3GPP, for an LTE system, the bandwidth ratio to be scanned is wide, if traversing search is performed according to each possible frequency point, a long time is often required, and great challenges are brought to power consumption.
Currently, the mainstream scheme is to perform auto-correlation or cross-correlation detection with the local PSS signal, and most of the schemes perform sliding correlation in the time domain, because the PSS has three possible IDs, it needs to try the three IDs one by one.
Figure 443986DEST_PATH_IMAGE001
Figure 403589DEST_PATH_IMAGE002
Figure 974379DEST_PATH_IMAGE003
Then the
Figure 153688DEST_PATH_IMAGE004
Figure 366494DEST_PATH_IMAGE005
Figure 714692DEST_PATH_IMAGE006
And respectively finding out the maximum values in the PSS sequences of the three IDs, then comparing the maximum values corresponding to the three IDs, finding out the total maximum value and the ID, wherein the maximum value sequence is the corresponding main synchronous signal sequence, and determining the position of timing synchronization according to the position corresponding to the maximum value.
In the 3GPP protocol (36.101), the cell frequency point number (EARFCN) spacing is defined as 100KHz, but in practice the OFDM subcarrier spacing for LTE is 15 KHz. Thus, there is a certain fixed frequency offset in the frequency domain:
Figure 987542DEST_PATH_IMAGE007
. According to the conventional frequency-sweeping scheme, this fixed frequency offset degrades performance, resulting in the FFT output not being aligned with the local synchronization signal at some point, as shown in fig. 2. Because of the inherent frequency offset problem caused by frequency point misalignment, the network searching performance is poor.
Disclosure of Invention
In order to overcome the defect of poor network searching performance caused by inherent frequency offset in the prior art, the invention provides a method for realizing frequency point searching in an LTE system, which can improve the network searching performance.
The invention is realized by the following technical scheme: a method for searching frequency points in an LTE system is provided.
(1) Pre-frequency-offset is carried out on a local PSS sequence, and the sequence comprises original sequences without frequency offset
Figure 857409DEST_PATH_IMAGE008
With negative frequency offset sequence
Figure 372442DEST_PATH_IMAGE009
Sequence with positive frequency offset
Figure 808102DEST_PATH_IMAGE010
To ensure alignment in the frequency domain with the received signal.
(2) Superposing the local sequence after the pre-frequency deviation into a new local sequence
Figure DEST_PATH_IMAGE011
Figure 720694DEST_PATH_IMAGE012
Figure 100002_DEST_PATH_IMAGE014
Wherein:
Figure 48164DEST_PATH_IMAGE015
Figure 868352DEST_PATH_IMAGE016
Figure 158519DEST_PATH_IMAGE017
m: for the length of each data block, i.e. the length of the FFT;
Δ f is pre-frequency offset;
j: coordinates of sampling points in each data block;
(3) in the frequency domain, the actual received signal is multiplied by the new local sequence
Figure 537286DEST_PATH_IMAGE018
Wherein:
n is the nth data block divided in time domain;
x (n) is frequency domain data of the nth data block after FFT;
x (n, j) is a j sampling point of the nth data block and can be regarded as a two-dimensional array;
Figure 116166DEST_PATH_IMAGE019
is as followsA new local sequence of j sample points;
(4) then, find the maximum value in the time domain
Figure 100002_DEST_PATH_IMAGE020
(5) Then, the maximum correlation time offset is found out by adopting an overlap-add or overlap-reserve method
Figure 382456DEST_PATH_IMAGE021
Where N is the number of data blocks, and the time offset is calculated by accumulating all the data blocks.
The invention has the beneficial effects that: 1) the local PSS sequence is subjected to pre-frequency offset to ensure that the local PSS sequence is aligned with a received signal in a frequency domain, so that the problem of poor network searching performance caused by inherent frequency offset due to frequency point misalignment is solved. 2) The traditional 3 times of calculation related to sliding is changed into 1 time of calculation, the searching performance is improved, and the problems of slow network searching and large power consumption caused by long time required by the adjacent frequency point attempt due to wide LTE bandwidth are solved.
Drawings
FIG. 1 is a block diagram of an implementation of the present invention.
Fig. 2 is a schematic diagram of the 2.5KHZ frequency offset of the present invention.
FIG. 3 is a schematic diagram of the present invention after 2.5KHZ pre-frequency offset.
FIG. 4 is a block diagram of the data of the present invention.
FIG. 5 is a comparative graphical representation of the detection capabilities of the present invention.
Fig. 6 is a graph illustrating the comparison of the frequency offset resistance performance under the fading channel.
Fig. 7 is a graph comparing interference rejection capabilities.
Detailed Description
The invention is described in further detail below with reference to the figures and the detailed description.
As shown in fig. 1, the implementation process of the present invention is as follows, after a signal is sampled and received, the signal is stored, then the data is subjected to block division and overlap addition or 0 complement preparation of an overlap preservation method, then FFT conversion is performed on each data block, that is, converted into frequency domain data x (n), frequency point data selection is performed according to a cell frequency point (EARFCN) supported by equipment, the selected frequency point data is multiplied by a PSS signal which is preprocessed (the following two steps (1) and (2)), and then is subjected to IFFT conversion processing to convert into time domain data, then effective data is intercepted according to the selected overlap addition or overlap preservation method, and the maximum value of each data block is found, and then the maximum value is found in all data blocks.
The algorithm is as follows:
(1) pre-frequency-offset is carried out on a local PSS sequence, and the sequence comprises original sequences without frequency offset
Figure 792708DEST_PATH_IMAGE008
With negative frequency offset sequence
Figure 312683DEST_PATH_IMAGE009
Sequence with positive frequency offset
Figure 175596DEST_PATH_IMAGE010
To ensure alignment in the frequency domain with the received signal, as shown in fig. 3.
(2) Superposing the local sequence after the pre-frequency deviation into a new local sequence
Figure 836123DEST_PATH_IMAGE011
Figure 632040DEST_PATH_IMAGE012
Figure 791757DEST_PATH_IMAGE014
Wherein:
Figure 834976DEST_PATH_IMAGE015
Figure 800658DEST_PATH_IMAGE022
Figure 919923DEST_PATH_IMAGE023
m: for the length of each data block, i.e. the length of the FFT;
Δ f is pre-frequency offset;
j: coordinates of the sample points in each data block.
(3) In the frequency domain, the actual received signal is multiplied by the new local sequence
Figure 47279DEST_PATH_IMAGE018
Wherein:
n is the nth data block divided in time domain;
x (n) is frequency domain data of the nth data block after FFT;
x (n, j) is a j sampling point of the nth data block and can be regarded as a two-dimensional array;
Figure 648900DEST_PATH_IMAGE019
a new local sequence for the jth sample point;
as shown in fig. 3, the received signal is divided in the time domain into a number of data blocks, each of which n has a length of M.
(4) Then, find the maximum value in the time domain
Figure 152693DEST_PATH_IMAGE020
(5) Then, the maximum correlation time offset is found out by adopting an overlap-add or overlap-reserve method
Figure 392045DEST_PATH_IMAGE021
Where N is the number of data blocks, and the time offset is calculated by accumulating all the data blocks.
Because the frequency deviation reduces the frequency sweeping performance, the invention carries out pre-frequency deviation on the local PSS sequence to ensure that the local PSS sequence is aligned with the received signal in the frequency domain, thereby solving the problem of poor network searching performance caused by inherent frequency deviation caused by frequency point misalignment.
Obtaining a new synchronization sequence by superimposing the pre-frequency offset processed sequences
Figure 690302DEST_PATH_IMAGE024
Then, the received signal is summed in the frequency domain
Figure 719831DEST_PATH_IMAGE024
Multiplying, reducing the traditional sliding-related 3 times of calculation to 1 time, improving the searching performance, and solving the problems of slow network searching and large power consumption caused by long time required by the adjacent frequency point attempt due to wide LTE bandwidth.
Fig. 4 is a schematic diagram of data blocking.
When the fixed frequency offset is 2.5KHZ, as shown in fig. 2, according to the conventional frequency sweep scheme, the fixed frequency offset may reduce performance, which may cause the output of the FFT to be misaligned with the local synchronization signal at some points, and the network searching performance is poor due to the inherent frequency offset caused by the misalignment of the frequency points.
As shown in fig. 3, the local PSS sequence is pre-frequency-shifted by 2.5KHZ to ensure that the received signal is aligned in the frequency domain, thereby solving the problem of poor network searching performance caused by inherent frequency offset due to frequency point misalignment.
The performance simulation is performed on the pre-frequency deviation and the non-pre-frequency deviation as follows:
the simulation parameters are as follows:
Figure 27316DEST_PATH_IMAGE025
two protocols were compared:
l 0 Hz: that is, the patent proposes, the local PSS band is pre-frequency offset processed;
l 2.5 KHz: in the traditional scheme, the local PSS is not subjected to pre-frequency offset processing;
compared with the traditional scheme, the scheme provided by the patent has obvious advantages when the signal-to-noise ratio is lower than 2.5dB, and the advantage is more obvious when the signal-to-noise ratio is lower. When the signal-to-noise ratio is equal to-4.5 dB, the detection capability can be improved by more than 30%.
The detection capability is shown in fig. 5, the frequency offset resistance under the fading channel is shown in fig. 6, and the interference resistance is shown in fig. 7.

Claims (1)

1. A method for searching frequency points in an LTE system is characterized in that:
(1) pre-frequency-offset is carried out on a local PSS sequence, and the sequence comprises original sequences without frequency offset
Figure DEST_PATH_IMAGE002
With negative frequency offset sequence
Figure DEST_PATH_IMAGE004
Sequence with positive frequency offset
Figure DEST_PATH_IMAGE006
To ensure alignment with the received signal in the frequency domain;
(2) superposing the local sequence after the pre-frequency deviation into a new local sequence
Figure DEST_PATH_IMAGE008
Figure DEST_PATH_IMAGE010
Figure DEST_PATH_IMAGE012
Wherein:
Figure DEST_PATH_IMAGE014
Figure DEST_PATH_IMAGE016
Figure DEST_PATH_IMAGE018
m: for the length of each data block, i.e. the length of the FFT;
Δ f is pre-frequency offset;
j: coordinates of sampling points in each data block;
(3) in the frequency domain, the actual received signal is multiplied by the new local sequence
Figure DEST_PATH_IMAGE020
Wherein:
n is the nth data block divided in time domain;
x (n) is frequency domain data of the nth data block after FFT;
x (n, j) is a j sampling point of the nth data block and can be regarded as a two-dimensional array;
Figure DEST_PATH_IMAGE022
a new local sequence for the jth sample point;
(4) then, find the maximum value in the time domain
Figure DEST_PATH_IMAGE024
(5) Then, the maximum correlation time offset is found out by adopting an overlap-add or overlap-reserve method
Figure DEST_PATH_IMAGE026
Where N is the number of data blocks, and the time offset is calculated by accumulating all the data blocks.
CN201810980471.1A 2018-08-27 2018-08-27 Method for searching frequency point in LTE system Active CN109168186B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201810980471.1A CN109168186B (en) 2018-08-27 2018-08-27 Method for searching frequency point in LTE system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201810980471.1A CN109168186B (en) 2018-08-27 2018-08-27 Method for searching frequency point in LTE system

Publications (2)

Publication Number Publication Date
CN109168186A CN109168186A (en) 2019-01-08
CN109168186B true CN109168186B (en) 2021-04-06

Family

ID=64896754

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201810980471.1A Active CN109168186B (en) 2018-08-27 2018-08-27 Method for searching frequency point in LTE system

Country Status (1)

Country Link
CN (1) CN109168186B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111132272A (en) * 2019-12-31 2020-05-08 重庆邮电大学 Cell search timing synchronization method for 5G NR system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105704783A (en) * 2014-11-24 2016-06-22 中国移动通信集团公司 Frequency sweep interval determination method and device, terminal frequency sweep method and device, and terminal
CN105847212A (en) * 2016-03-23 2016-08-10 北京裕源大通科技股份有限公司 Detection method and device of downlink primary synchronization signals in LTE system
CN106162813A (en) * 2015-03-24 2016-11-23 中兴通讯股份有限公司 A kind of small region search method and device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20160092415A (en) * 2015-01-27 2016-08-04 엘지전자 주식회사 Mobile terminal and method for controlling the same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105704783A (en) * 2014-11-24 2016-06-22 中国移动通信集团公司 Frequency sweep interval determination method and device, terminal frequency sweep method and device, and terminal
CN106162813A (en) * 2015-03-24 2016-11-23 中兴通讯股份有限公司 A kind of small region search method and device
CN105847212A (en) * 2016-03-23 2016-08-10 北京裕源大通科技股份有限公司 Detection method and device of downlink primary synchronization signals in LTE system

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
LTE终端小区搜索算法研究;崔子川 宋利利;《现代商贸工业》;20130930;全文 *
NR inter-RAT mobility to LTE CSG cell;LG Electronics Inc.;《3GPP TSG-RAN2 Meeting #103 R2-1812878》;20180810;全文 *

Also Published As

Publication number Publication date
CN109168186A (en) 2019-01-08

Similar Documents

Publication Publication Date Title
CN110519196B (en) Method for searching physical cell identity, computer readable storage medium and small base station
US9107158B2 (en) Robust downlink timing synchronization method in LTE system
CN106105361A (en) The transmission of random access lead code signal and reception
CN108924943B (en) Maximum correlation estimation detection method based on narrowband Internet of things random access channel
US8718641B2 (en) Cell search method in wireless communication system
EP1869909A2 (en) System and method for ranging
CN107819717B (en) Frequency domain field intensity searching method based on PUSCH in LTE interference
WO2011157134A2 (en) Interference detection between base stations and base station
CN110912645A (en) 5G NR downlink synchronization method and system based on SDR platform
WO2014063275A1 (en) Method for determining remote same-frequency interference source and locating method therefor
CN101998586A (en) Method and device for searching PLMN (Public Land Mobile Network) of TD-LTE (Time Division-LongTerm Evolution)
CN102014461B (en) Frequency-sweeping method and device used for TD-LTE (Time Division-Long Term Evolution)
CN101039499B (en) CAZAC sequence-based cell searching structure of multi-carrier communication and searching method thereof
CN102271384B (en) Primary cell searching method for long term evolution (LTE) system
CN103905363A (en) Secondary synchronization signal (SSS) detection method and device and network mode judgment method
CN109168186B (en) Method for searching frequency point in LTE system
CN105634542B (en) A kind of TD-SCDMA multi-cell searchs method
CN112714448B (en) Method for detecting master synchronizing signal in dynamic spectrum sharing
CN113438730A (en) Wireless positioning method based on GFDM signal
CN103441830A (en) Timing synchronization method based on sounding reference signal
CN108989259A (en) The time offset estimation method and system of wireless comprehensive test instrument narrowband Physical Uplink Shared Channel
RU2721157C1 (en) Broadband detection of a synchronization signal in an nr system
KR101629680B1 (en) Downlink synchronization method for lte system
US10536913B2 (en) Methods and device for improved cell synchronization
CN104735002B (en) A kind of removing method and terminal of interference signal

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant