CN107295535A - A kind of GSM R systems frequency shift (FS) auto-correction method - Google Patents
A kind of GSM R systems frequency shift (FS) auto-correction method Download PDFInfo
- Publication number
- CN107295535A CN107295535A CN201710498856.XA CN201710498856A CN107295535A CN 107295535 A CN107295535 A CN 107295535A CN 201710498856 A CN201710498856 A CN 201710498856A CN 107295535 A CN107295535 A CN 107295535A
- Authority
- CN
- China
- Prior art keywords
- frequency
- gsm
- frames
- fcch
- auto
- 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.)
- Pending
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W24/00—Supervisory, monitoring or testing arrangements
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/10—Monitoring; Testing of transmitters
- H04B17/11—Monitoring; Testing of transmitters for calibration
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/20—Monitoring; Testing of receivers
- H04B17/21—Monitoring; Testing of receivers for calibration; for correcting measurements
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
Abstract
The present invention provides a kind of GSM R systems frequency shift (FS) auto-correction method, searches for 124 channels, i.e., all BCH passages carry out power scan to them, select most strong bcch carrier to be stationed；Detect FCCH frames；Next frame search SCH frames of FCCH frames are being found, are being demodulated afterwards, the characteristics of quickly being moved for railway, pass through the frequency shift (FS) for quickly estimating to be brought by high-speed mobile, compensate again, so as to reduce the influence that Doppler effect communicates to GSM R, improve the communication quality of GSM R systems.
Description
Technical field
The present invention relates to a kind of GSM-R system frequency excursions auto-correction method.
Background technology
GSM-R be merged on the basis of public network GSM technology dispatching communication function dedicated for railway wireless communication
Digital clustering communication system.GSM-R outstanding features are that High Speed Railway Trains are automatically controlled into the transmission of information and with voice communication
Based on dispatching communication uniformly include same radio communication platform, be that One function is perfect, realize Signal ＆ Communication Integration
Advanced efficient communication system.
At present, GSM-R digital mobile communication systems are the communication mode of China railways mobile communication standard；China has turned into
High-speed railway runs the country that mileage is most long, building scale is maximum in the world；In recent years, high speed railway construction is in worldwide
In high speed development trend, the fast development of high-speed railway is both an opportunity, is also one for high-speed railway wireless communication system
Individual huge challenge.With the continuous acceleration of Development of High Speed Railway, in order to adapt to the particularity of high-speed railway environment, and enter one
Step meets the growing communication requirement of mobile subscriber, and research is increasingly becoming based on GSM-R communication radio frequency extension unit systems
Focus, at the same time, the doppler shift effect under research high-speed railway scene are also cured to the importance of the design of communication system
Plus it is prominent.
In the case of high-speed mobile, due to Doppler effect between terminal and base station (or Remote Radio Unit), it can produce
Raw frequency shift (FS), so that synchronous be difficult to set up, keep.
The content of the invention
The technical problem to be solved in the present invention, is to provide a kind of GSM-R system frequency excursions auto-correction method, for
The characteristics of railway is quickly moved, by the frequency shift (FS) for quickly estimating to be brought by high-speed mobile, then compensates, so as to reduce
The influence that Doppler effect communicates to GSM-R, improves the communication quality of GSM-R systems.
What the present invention was realized in：A kind of GSM-R system frequency excursions auto-correction method, comprises the following steps：
Step 1,124 channels of search, i.e., all BCH passages carry out power scan to them, select most strong BCCH
Carrier wave is stationed；
Step 2, detection FCCH frames；
Step 3, next frame search SCH frames of FCCH frames are being found, be demodulated afterwards.
Further, the step 2 is specially further：Because data are complete 1 in FCCH frames, it is after gmsk is modulated
Frequency is 67kHz sine wave, carries out FFT computings to (2N+1) in the list entries of 156 bit longs individual frequency every time, if
FFT peak value continuously occurs in tap 8, then have found FCCH frames；Otherwise the list entries of next 156 bit is proceeded
Identical processing, until detecting FCCH frames.
Further, described (2N+1) individual frequency includes：67kHz frequencies, and centered on 67kHz frequencies, both sides are each
N number of frequency is chosen again.
Further, according to formula,
In above formula, Δ f is frequency deviation value, and T is receives the time interval between signal, and L is receives signal number, and R (m) is each letter
Correlation between number,
The FCCH frames detected are compensated by Δ f afterwards, accurate FCCH frames are obtained.
The invention has the advantages that：A kind of GSM-R system frequency excursions auto-correction method of the present invention, passes through search
124 BCH passages, bcch carrier is determined to its mode for carrying out power scan, then first carries out coarse frequency estimation using FFT,
After correction, the smart Frequency Estimation of method of correlation is reused, can effectively reduce and cause because bullet train is quickly mobile after essence estimation
Doppler shift.
Brief description of the drawings
The present invention is further illustrated in conjunction with the embodiments with reference to the accompanying drawings.
Fig. 1 is that GSM-R communication system frequencies offset automatic correction device block diagram.
Fig. 2 is mapping schematic diagrames of the FCCH and SCH in 51 superframes.
Fig. 3 is the search schematic diagram to FCCH and SCH.
Fig. 4 is FCCH Frequency Synchronization flow charts.
Fig. 5 is the synchronous flow chart of FCCH essences.
Embodiment
GSM-R system frequency excursions auto-correction method of the present invention, comprises the following steps：
Step 1,124 channels of search, i.e., all BCH passages carry out power scan to them, select most strong BCCH
Carrier wave is stationed；
Step 2, due in FCCH frames data be complete 1, be the sine wave that frequency is 67kHz after gmsk is modulated, every time
(2N+1) individual frequency carries out FFT computings in the list entries of 156 bit longs, if FFT peak value continuously occurs in tap 8,
It then have found FCCH frames；Otherwise identical processing is proceeded to the list entries of next 156 bit, until detecting FCCH
Frame, (2N+1) the individual frequency includes：67kHz frequencies, and centered on 67kHz frequencies, N number of frequency is respectively chosen on both sides again,
According to formula,
In above formula, Δ f is frequency deviation value, and T is receives the time interval between signal, and L is receives signal number, and R (m) is each letter
Correlation between number, is afterwards compensated the FCCH frames detected by Δ f, obtains accurate FCCH frames；
Step 3, next frame search SCH frames of FCCH frames are being found, be demodulated afterwards.
Main application scenarios：
GSM-R system auto frequency offsets means for correcting is applied to high-speed railway (more than 350km/h), maglev
(speed per hour is up to 431km/h), subway etc. lead to not connect due to doppler shift effect, the occasion of the existing picture such as call drop.The dress
Put low with easy for installation, construction investment, the advantages of instant effect, with high cost performance.Equipment block diagram is as shown in Figure 1.Respectively
Function, which is referred to, to be described as follows：
1) low noise amplifier
Low-noise amplifier is carried out to the faint GSM-R radiofrequency signals that business antenna end is inputted, reduction base station receives noise
Level, improves signal to noise ratio.
2) frequency mixer (descending)
Frequency spectrum shift is carried out to radiofrequency signal, radiofrequency signal is moved to intermediate frequency and is handled.
3)A/D
Analog signal digital, is converted into data signal by analog signal and is handled.
4)FPGA
Data signal after being changed through A/D gives FPGA and is demodulated processing, calculates its frequency error, and this frequency is missed
Difference can solve Doppler frequency shift caused by excessive velocities handoff procedure as the frequency deviation of output reference frequency.(specific AFC
Process is with reference to following AFC operation principles)
5)D/A
Data signal is simulated, converts digital signals into analog signal and is handled.
6) frequency mixer (up)
Frequency spectrum shift is carried out to intermediate-freuqncy signal, intermediate-freuqncy signal is moved to emission of radio frequency signals and goes out.
2.2.1 operation principle：
The device completes synchronous between base station by logic channel (FCCH, SCH).Wherein FCCH is used for completing frequency
Essence/thick synchronous and time is slightly synchronous, and it is synchronous that SCH is used for deadline essence.FCCH and SCH framing bits in the 0th time slot of 51 superframes,
As shown in Figure 2.
After start, the operation relevant with synchronization that mobile station is carried out is:
The first step：124 channels are searched for, i.e., all BCH passages carry out power scan to them, selected most strong
Bcch carrier is stationed；
Second step：Detect FCCH frames
Continuous detection, at most 11 frames of detection, must can find FCCH (by the structures shape of 51 superframes)；
Frequency rough/essence estimation, time rough estimate；
3rd step：Finding next frame search SCH frames of FCCH frames
Time essence estimation and compensation；
SCH data are demodulated.
Second step and the 3rd step are as shown in Figure 3.
GSM-R remote radio unit systems additionally use answering for its system of series of algorithms foot during designing and developing
With characteristic, here is detailed to introduce FCCH detection, coarse frequency synchronization and frequency precise synchronization in AFC devices：
1) FCCH detection and coarse frequency synchronization
FCCH frames be base station send Frequency Synchronization frame (data be complete 1), alignment and reduction for mobile station frame boundaries
Frequency error.FCCH frames do not contain useful information, so need not demodulate.It is only used for frequency rough/essence synchronous slightly synchronous with the time.
Agreement provides that the error of coarse frequency synchronization is 10ppm (20kHz), and the synchronous error of essence is 0.1pp m (200Hz).
As shown in figure 4, the characteristics of FCCH detection and coarse frequency synchronization take full advantage of FCCH frames.Because number in FCCH frames
It is the sine wave that frequency is 67kHz after gmsk is modulated, we enter to the list entries of 156 bit longs every time according to for complete 1
The point FFT computings of row 32, window a length of 32.
In view of the simplification of realization, without being operated to all 32 points, which part point can be only chosen, but necessarily
67kHz, this frequency is included, and general consideration is that centered on 67kHz frequencies, N number of point is respectively chosen on both sides again, i.e.,
Common (2N+1) individual frequency.The method that we use is only this 5 points of calculating the 6th, 7,8,9,10, wherein the 8th point correspondence is most
Accurate 270/32*8=67kHz. is because the thick synchronous precision of regulation is 20kHz, and 5 points of selection can just meet (270/
32*2)。
If FFT peak value continuously occurs in tap 8, it is believed that have found FCCH frames；Otherwise to next 156 bit
List entries proceed identical processing.At most search for continuous 11 frame, you can complete FCCH detections and coarse frequency synchronization.
After the completion of thick synchronous precision ± 4.23kHz (270/32) coarse frequency synchronizations, mobile station can adjust local frame boundaries, phase
The time answered slightly synchronously also completes.Time precision is ± 16 symbols (window length 32).
FCCH frequency precise synchronization
After rough estimate, down coversion is carried out with the frequency values of rough estimate to all input datas, the signal so obtained
Frequency spectrum is certainly in the range of 67KHz ± 4.25kHz, it is possible to first LPF in the range of this.FCCH synchronization is filled
Divide the special construction that make use of its frame, after GMSK modulation, FB is the standard sine wave that a frequency is 67KHz, therefore is utilized
Selective FFT method to it carries out frame-grab and coarse frequency synchronization, after thick synchronous result compensation；(we utilize phase
It is synchronous to enter the frequency essence of line frequency to close the method for summation) the synchronous flow of essence is as shown in Figure 5.
Smart estimation is related method.Algorithm is derived below, and derivation is in order to which easy orders receive signal
X (n)=ejωn, it is added without initial phase and white noise, the related of white noise is still white noise, and the influence of initial phase can be with
It is included in noise.
After rough estimate, set receive signal expression as：ejωnT, utilize formulaObtain
Function it is relevant with frequency deviation Δ ω, ω be receive frequency, ω1It is the frequency by rough estimate,
The method for solving frequency deviation is to use auto-correlation principle,
Here ZkFor 142Bit data in FB.Detailed derivation is as follows：
Due toSo having
Correlation is summed
(geometric progression)
ρ is constant in above formula.Above formula can be write as：
Wherein, π Δs fT (L+1) isArgument, have
Therefore
T is receives the time interval between signal in above formula, and L is receives signal number, and R (m) is the correlation between each signal
Value.The frequency deviation tried to achieve is used for adjusting the frequency of reception, with synchronous with base station frequency.
Mobile station is in start, preliminary and base station synchronization, and not only frequency is present there is also deviation in deviation, and time,
The time deviation in the range of -16T~16T can be obtained in FCCH search methods.
Although the foregoing describing the embodiment of the present invention, those familiar with the art should manage
Solution, the specific embodiment described by us is merely exemplary, rather than for the restriction to the scope of the present invention, is familiar with this
The equivalent modification and change that the technical staff in field is made in the spirit according to the present invention, should all cover the present invention's
In scope of the claimed protection.
Claims (4)
1. a kind of GSM-R system frequency excursions auto-correction method, it is characterised in that：Comprise the following steps：
Step 1,124 channels of search, i.e., all BCH passages carry out power scan to them, select most strong bcch carrier
It is stationed；
Step 2, detection FCCH frames；
Step 3, next frame search SCH frames of FCCH frames are being found, be demodulated afterwards.
2. a kind of GSM-R system frequency excursions auto-correction method according to claim 1, it is characterised in that：The step
Rapid 2 are specially further：It is the sine wave that frequency is 67kHz after gmsk is modulated, often because data are complete 1 in FCCH frames
(2N+1) individual frequency carries out FFT computings in the secondary list entries to 156 bit longs, if FFT peak value continuously goes out in tap 8
It is existing, then it have found FCCH frames；Otherwise identical processing is proceeded to the list entries of next 156 bit, until detecting
FCCH frames.
3. a kind of GSM-R system frequency excursions auto-correction method as claimed in claim 2, it is characterised in that：(the 2N+
1) individual frequency includes：67kHz frequencies, and centered on 67kHz frequencies, N number of frequency is respectively chosen on both sides again.
4. a kind of GSM-R system frequency excursions auto-correction method as claimed in claim 2, it is characterised in that：
According to formula,
In above formula, Δ f be frequency deviation value, T for receive signal between time interval, L for receive signal number, R (m) be each signal it
Between correlation,
The FCCH frames detected are compensated by Δ f afterwards, accurate FCCH frames are obtained.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710498856.XA CN107295535A (en) | 2017-06-27 | 2017-06-27 | A kind of GSM R systems frequency shift (FS) auto-correction method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710498856.XA CN107295535A (en) | 2017-06-27 | 2017-06-27 | A kind of GSM R systems frequency shift (FS) auto-correction method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN107295535A true CN107295535A (en) | 2017-10-24 |
Family
ID=60098482
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710498856.XA Pending CN107295535A (en) | 2017-06-27 | 2017-06-27 | A kind of GSM R systems frequency shift (FS) auto-correction method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107295535A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114401177A (en) * | 2022-03-24 | 2022-04-26 | 北京理工大学 | Frame synchronization method and device, electronic equipment and storage medium |
| CN116298513A (en) * | 2023-03-01 | 2023-06-23 | 扬州宇安电子科技有限公司 | Broadband spectrum monitoring system with multiple scanning modes |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060030365A1 (en) * | 2002-04-16 | 2006-02-09 | Omri Hovers | Method and apparatus for synchronizing a smart antenna apparatus with a base station transceiver |
| CN101365227A (en) * | 2007-08-10 | 2009-02-11 | 大唐移动通信设备有限公司 | Method, apparatus and mobile terminal acquiring synchronous timing of GSM adjacent cells |
| CN102685047A (en) * | 2012-05-25 | 2012-09-19 | 京信通信系统（中国）有限公司 | Global system for mobile communication (GSM) frequency deviation estimation method and system |
| CN103096452A (en) * | 2011-10-28 | 2013-05-08 | 联芯科技有限公司 | Method and device of acquiring frequency correction burst (FB) |
-
2017
- 2017-06-27 CN CN201710498856.XA patent/CN107295535A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060030365A1 (en) * | 2002-04-16 | 2006-02-09 | Omri Hovers | Method and apparatus for synchronizing a smart antenna apparatus with a base station transceiver |
| CN101365227A (en) * | 2007-08-10 | 2009-02-11 | 大唐移动通信设备有限公司 | Method, apparatus and mobile terminal acquiring synchronous timing of GSM adjacent cells |
| CN103096452A (en) * | 2011-10-28 | 2013-05-08 | 联芯科技有限公司 | Method and device of acquiring frequency correction burst (FB) |
| CN102685047A (en) * | 2012-05-25 | 2012-09-19 | 京信通信系统（中国）有限公司 | Global system for mobile communication (GSM) frequency deviation estimation method and system |
Non-Patent Citations (2)
| Title |
|---|
| 梁光胜等: ""基于SDR的GSM移动终端同步算法的研究及实现"", 《中国电力教育》 * |
| 邱烈义等: ""非安全数字移动通信标准网络监听平台的设计与数字处理器实现"", 《科学技术与工程》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114401177A (en) * | 2022-03-24 | 2022-04-26 | 北京理工大学 | Frame synchronization method and device, electronic equipment and storage medium |
| CN116298513A (en) * | 2023-03-01 | 2023-06-23 | 扬州宇安电子科技有限公司 | Broadband spectrum monitoring system with multiple scanning modes |
| CN116298513B (en) * | 2023-03-01 | 2024-03-12 | 扬州宇安电子科技有限公司 | Broadband spectrum monitoring system with multiple scanning modes |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| RU2464721C2 (en) | Methods and devices for synchronisation and detection in wireless communication systems | |
| US8576830B2 (en) | Method and system for tracking timing drift in multiple frequency hypothesis testing | |
| JP5117507B2 (en) | Wireless communication system, synchronization method between base stations, and base station | |
| CN103475614B (en) | Method and device for frequency offset estimation and compensation | |
| US20040097190A1 (en) | Mobile unit position determination using RF signal repeater | |
| CN101990291B (en) | Method for pre-compensating frequency bias as well as device | |
| US20080316911A1 (en) | Simultaneous Cell Group and Cyclic Prefix Detection Method, Apparatus and System | |
| CN101473620A (en) | Method and apparatus for using the synchronization channel to obtain measurements of neighboring cells in an OFDM communications system | |
| KR20120036018A (en) | Apparatus and method for frequency offset estimation for high speed in wireless communication system | |
| WO2014063275A1 (en) | Method for determining remote same-frequency interference source and locating method therefor | |
| CN102480443B (en) | Carrier frequency offset estimation method and device for mobile communication system | |
| US10439859B2 (en) | Synchronization in mixed OFDM sub-carrier spacing scenarios | |
| US9621340B1 (en) | Method and device for detecting primary synchronization signal in LTE and LTE advanced communication system | |
| CN106953823B (en) | A kind of wireless communication high-precision frame synchornization method based on synchronizing sequence | |
| US20100311346A1 (en) | Communication Device and Method | |
| CN101753492A (en) | Method and system for correcting frequency offset of mobile communication terminal | |
| CN107295535A (en) | A kind of GSM R systems frequency shift (FS) auto-correction method | |
| US20090232051A1 (en) | Method and system for the extension of frequency offset estimation range based on correlation of complex sequences | |
| CN111083777A (en) | PSS timing synchronization method and system based on conjugate symmetry in 5G system | |
| CN102752713A (en) | Wireless locating method based on long-term evolution signal system, and terminal | |
| WO2022115041A1 (en) | Methods and communication apparatuses for 5g-based positioning | |
| CN101630961B (en) | Frequency bias estimation equipment, method and communication device | |
| WO2003058808A1 (en) | Fast timing acquisition for multiple radio terminals | |
| JP2004528777A (en) | Apparatus for synchronizing a transmitter and a receiver in a communication system | |
| KR101629680B1 (en) | Downlink synchronization method for lte system |
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 | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20171024 |
|
| RJ01 | Rejection of invention patent application after publication |