CN106603131A - Frame synchronization method for MIMO system - Google Patents
Frame synchronization method for MIMO system Download PDFInfo
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- CN106603131A CN106603131A CN201710062976.5A CN201710062976A CN106603131A CN 106603131 A CN106603131 A CN 106603131A CN 201710062976 A CN201710062976 A CN 201710062976A CN 106603131 A CN106603131 A CN 106603131A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2656—Frame synchronisation, e.g. packet synchronisation, time division duplex [TDD] switching point detection or subframe synchronisation
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Synchronisation In Digital Transmission Systems (AREA)
- Radio Transmission System (AREA)
Abstract
The invention discloses a frame synchronization method for an MIMO system. A low-pass filter is designed to filter the interference of the data part of MIMO wireless frames to the process of synchronization, so that the stability of synchronization is improved. Through down-sampling, the complexity of the follow-up cross-correlation algorithm is reduced greatly. In addition, by judging the effectiveness of the synchronization position, the reliability of the system is enhanced. The MIMO system frame synchronization method is applicable to a system frame structure of which the frames are synchronized using a synchronization sequence, and greatly improves the efficiency of synchronization.
Description
Technical field
The present invention relates to a kind of frame synchornization method of mimo system, belongs to mobile communication technology field.
Background technology
In MIMO (Multiple-Input Multiple-Output) technology, transmitting terminal and receiving terminal are respectively using more
Root antenna improves channel quality improving channel capacity, and this technology takes full advantage of space resources, in limited frequency spectrum resource
Under can significantly improve system channel capacity, wherein massive MIMO technologies have become the important skill in future mobile communications field
One of art.
The development of MIMO also brings many problems for needing and solving, such as the Problem of Frame Synchronization of system wireless signal.Mesh
The front frame synchornization method for mimo system receiving terminal multiple antennas is little, particularly in massive mimo systems, receiving terminal
Substantial amounts of antenna is configured with, frame synchronization resource overhead and how to handle some antennas well that a large amount of reception antennas bring how is reduced
The problems such as can not carrying out frame synchronization due to the impact of barrier becomes the difficult point of system design, for this reason, it may be necessary to propose a kind of multiple
It is miscellaneous to spend the good frame synchronization algorithm of relatively low, robustness.
In mimo systems, the multiple antennas of transmitting terminal synchronously send the wireless signal with certain frame structure, and this is wireless
Signal can insert synchronizing sequence on fixed position, and the main points that synchronizing sequence is selected are that to have good autocorrelation, while
In order to reduce excessive occupancy of the synchronizing sequence to system limited spectrum resources, general synchronizing sequence adopts the low-pass signal of arrowband,
How the pass of mimo system frame synchronization is become by the starting position for determining radio frames to the detection of the narrow-band low pass signal
Key point, is also that the system subsequently carries out the basis that MIMO demodulation is relied on.
The content of the invention
Goal of the invention：In order to overcome the deficiencies in the prior art, the present invention to provide a kind of frame for mimo system
Synchronous method, this method solves the Problem of Frame Synchronization of multiple antennas in mimo system, at the same answer in right massive MIMO
The complexity run under extensive antenna and validity problem, can rapidly and accurately be found in time wirelessly by this synchronous method
The sync bit of frame.
Technical scheme：For achieving the above object, the technical solution used in the present invention is：
A kind of frame synchornization method for mimo system, it is adaptable to mimo system, by the synchronization for detecting MIMO radio frames
, to find the position of the sequence, so as to carry out time synchronized to MIMO radio frames, technical scheme is as follows for sequence：
(1) by radio frequency reception to data carry out LPF, filter the out-of-band signal of synchronizing signal.
(2) low-pass signal after LPF is carried out down-sampled.
(3) cross-correlation is carried out with local synchronous time domain signal with the signal after down-sampled.
(4) modulus computing and in a radio frame search peak are carried out to computing cross-correlation result, with the position of peak value
Come the positioning for synchronizing, sync bit is found.
(5) mean value that the peak value for finding is exported with cross-correlator is compared, if less than mean value certain multiple,
The peak value for then searching is invalid.
(6) side-play amount of the peak and peak before for finding is calculated, it is invalid to position if skew is too big.
(7) mode is asked to the effective sync bit on many antennas being found, as the synchronization of final whole receiving terminal
Position.
Preferably, in transmitting terminal, all antennas synchronously send with the wireless of the same MIMO frame structures methods described
Frame, must send identical synchronizing sequence on every antenna.
Preferably, in step (1), the cut-off frequency of low pass filter is the bandwidth of synchronizing signal.
Preferably, in step (2), the setting of down-sampled multiple will can guarantee that：Down-sampled low-pass signal frequency spectrum afterwards is not
Aliasing.
Preferably, in step (3), described local synchronous time domain signal is the local synchronizing signal for generating through drop
Signal after sampling, every antenna receive and through LPF and it is down-sampled after signal simultaneously with local synchronization letter
Number cross-correlation is carried out, obtain the cross correlation results on every reception antenna, the window size of described cross-correlator is original synchronization
The length of time-domain signal is divided by down-sampled multiple.
Preferably, in step (4), search peak is within the time of a radio frames, to find in the time period mutually
The maximum of the modulus value of device output is closed, the position in the maximum place radio frames positions to synchronizing signal, needs mutual
One counter, for counting to each output of cross-correlator, the meter of counter are set after the output of correlator
One number time be total sampling number of a MIMO radio frames divided by down-sampled multiple, the design docking of counter collects mail number each
Point is positioned.
Preferably, in step (5), the basis for judging the validity of peak value is that peak value is far longer than cross-correlator output number
According to mean value this property.
Preferably, in step (6), the validity of sync bit is judged, because being to connect between radio frames in mimo system
It is continuous, thus receiving terminal before and after radio frames sync bit will not offset it is too big.
Preferably, in step (7), looking for the purpose one of mode can prevent some antenna timing errors and cause to be performance
Decline to a great extent, two is to look for mode process, and amount of calculation is little, it is easy to which system is realized.
The present invention compared to existing technology, has the advantages that：
The MIMO frame synchornization methods of the present invention, employ the design of low pass filter, have filtered MIMO wireless frame datas portion
Divide the interference to synchronizing process, improve synchronous stability, while down-sampled addition, greatly reduces follow-up cross-correlation and calculate
The complexity of method, it is possible to additionally incorporate the availability deciding of sync bit, strengthen the reliability of system.This mimo system frame synchronization
Method, it is adaptable to the system frame structure of frame synchronization is carried out using synchronizing sequence, synchronous efficiency is greatly improved.
Description of the drawings
Fig. 1 is the MIMO frame synchronization algorithm block diagrams of the present invention.
The amended LTE frame structures that Fig. 2 is used for present example.
Synchronous subframe structure in the amended LTE frame structures that Fig. 3 is used for present example.
Fig. 4 is cross-correlator output result, comprising multiple radio frames.
Fig. 5 is cross-correlator output result, comprising single radio frames.
Specific embodiment
Below in conjunction with the accompanying drawings and specific embodiment, the present invention is further elucidated, it should be understood that these examples are merely to illustrate this
Invention rather than restriction the scope of the present invention, after the present invention has been read, those skilled in the art are various to the present invention's
The modification of the equivalent form of value falls within the application claims limited range.
A kind of frame synchornization method for mimo system, as Figure 1-4, it is adaptable to mimo system, by detecting MIMO
The synchronizing sequence of radio frames, so as to carry out time synchronized to MIMO radio frames, is comprised the steps with finding the position of the sequence：
(1) by radio frequency reception to data LPF is carried out by low pass filter, filter synchronizing signal out-of-band
Signal.Wherein, the cut-off frequency of low pass filter is the bandwidth of synchronizing signal.
(2) low-pass signal after LPF is carried out down-sampled.The setting of down-sampled multiple will can guarantee that：It is down-sampled
Low-pass signal frequency spectrum not aliasing afterwards.
(3) cross-correlation is carried out with local synchronous time domain signal with the signal after down-sampled.
Local synchronous time domain signal is signal of the local synchronizing signal for generating after down-sampled, every antenna institute
Receive and through LPF and it is down-sampled after signal simultaneously cross-correlation is carried out by cross-correlator with local synchronization signal,
The cross correlation results on every reception antenna are obtained, the window size of described cross-correlator is the length of original synchronous time domain signal
Divided by down-sampled multiple.
(4) modulus computing and in a radio frame search peak are carried out to computing cross-correlation result, with the position of peak value
Come the positioning for synchronizing, sync bit is found.
Search peak is that the maximum of the modulus value of cross-correlator output in the time period is found within the time of a radio frames
Value, the position in the maximum place radio frames positions to synchronizing signal, needs to be arranged after the output of cross-correlator
One counter, for counting to each output of cross-correlator, the counting cycle of counter is that a MIMO is wireless
Total sampling number of frame divided by down-sampled multiple, dock number each point of collecting mail and positioned by the design of counter.
(5) mean value that the peak value for finding is exported with cross-correlator is compared, if less than mean value certain multiple,
The peak value for then searching is invalid.
The basis for judging the validity of peak value is this property for the mean value that peak value is far longer than cross-correlator output data
Matter.
(6) side-play amount of the peak and peak before for finding is calculated, it is invalid to position if skew is too big.
In step (6), the validity of sync bit is judged, because in mimo system between radio frames being continuous, institute
Will not be offset with the sync bit of radio frames before and after receiving terminal too big.
(7) mode is asked to the effective sync bit on many antennas being found, as the synchronization of final whole receiving terminal
Position.
In step (7), the purpose one for looking for mode be can prevent some antenna timing errors and cause be performance significantly under
Drop, two is to look for mode process, and amount of calculation is little, it is easy to system realization, improves the robustness of system synchronization algorithm.
In transmitting terminal, all antennas synchronously send the radio frames with the same MIMO frame structures, must on every antenna
Beard and hair send identical synchronizing sequence.
Example
With reference to the embodiment description present invention of 16x4 MIMO ofdm systems.
, using the frame format similar to LTE, specific frame structure is not for the frame format of 16x4 MIMO ofdm system emitters
Become, simply have modified the sign pattern of some transmission symbols in radio frames.One radio frames of 16x4 MIMO ofdm systems are
10ms, is divided into 10 subframes, and each subframe is divided into 2 slot, and each slot point is 7 OFDM symbols, and each symbol is adopted
2048 points of IFFT modulation, adds corresponding Cyclic Prefix each radio frames and has 307200 data points.In first slot
First OFDM symbol on be put into PSS signals, the PSS signals carry out 2048 point IFFT and obtain by 62 point ZC sequences zero paddings, are
Low frequency signal, bandwidth 0.465MHz, emitter must continuously send the class LTE frame structure with PSS signals.
In receiving terminal, ADC samplings are carried out first, sample rate is 30.72MHz, obtains I/Q two paths of signals, through low pass drop
Sampling filter, a width of 0.5MHz of band that the wave filter is arranged, the system employs high-order Fir low pass filters, while the filter
Ripple device can configure sampling rate, be configured to 16 times and be capable of achieving down-sampled functions, and can guarantee that it is down-sampled after signal not aliasing.
Cross-correlator carries out 128 computing cross-correlations the signal after low pass is down-sampled with local PSS signals,
Local PSS signals are corresponding with the PSS time-domain signals that emitter sends, and original 2048 points are done with 16 times of sampling and is obtained,
Here what is done is plural cross-correlation, and it is to be merged to form by two real number cross-correlation to implement.
Peak value searching inside modules have a calculator, and the output to cross-correlation is counted, and cycle count 307200 is removed
With 16 --- 19200 points, for positioning to a frame data point, while carrying out modulus fortune to cross-correlator output plural number
Calculate, numerical value of the modulus value in the range of 19200 points in maximizing and counter when recording maximizing is designated as
ID, and modulus value is added up, when counter counts it is full 19200 when, export the peak value that finds and the corresponding ID of peak value with it is cumulative
Sum out, uses and obtains mean value.
The strategy for judging sync validity first determines whether whether peak value is more than 4 times of mean value, and 4 times is default value, according to
Specific communication environment can be changed, if it is determined that passing through, then judge whether the ID of peak value ensures phase in continuous 3 wireless frame ins
Adjacent peak I D difference is less than 5, if by being believed that synchronous success, exporting correct ID, and finds radio frames according to ID
Starting position, first have to be multiplied by ID 16 here, then deduct certain skew, offset it is relevant with concrete implementation details, this
In skew be 2440 or so, be 2048 (PSS length)+160 (Cyclic Prefix)+232 (low pass filter, cross-correlator postpones),
Output result is the original position of radio frames.
Finally merge the frame synchronization information on all 16 reception antennas, look for mode in all of effective synchronous ID, such as
Fruit does not have effective synchronization ID then output system frame synchronization failure signals, shows not receive radio frame signal.If be successfully found
Mode, output system frame synchronization pass signal, and the mode is exported, as the frame synchronization position on all reception antennas.
The above is only the preferred embodiment of the present invention, it should be pointed out that：For the ordinary skill people of the art
For member, under the premise without departing from the principles of the invention, some improvements and modifications can also be made, these improvements and modifications also should
It is considered as protection scope of the present invention.
Claims (6)
1. a kind of frame synchornization method for mimo system, it is characterised in that comprise the following steps：
Step 1, by radio frequency reception to data LPF is carried out by low pass filter, filter the out-of-band letter of synchronizing signal
Number；
Step 2, is carried out down-sampled to the low-pass signal after LPF；
Step 3, cross-correlation is carried out with the signal after down-sampled with local synchronous time domain signal；
Step 4, modulus computing and in a radio frame search peak are carried out to computing cross-correlation result, with the position of peak value come
The positioning for synchronizing, finds sync bit；
Step 5, the mean value that the peak value to finding is exported with cross-correlator is compared, if less than mean value certain multiple,
The peak value for then searching is invalid；
Step 6, calculates the side-play amount of the peak and peak before for finding, and it is invalid to position if skew is too big；
Step 7, to the effective sync bit on many antennas being found mode is sought, used as the sync bit of final whole receiving terminal
Put.
2. the frame synchornization method of mimo system is used for according to claim 1, it is characterised in that：In step 1, LPF
The cut-off frequency of device is the bandwidth of synchronizing signal.
3. the frame synchornization method of mimo system is used for according to claim 2, it is characterised in that：In step 2, down-sampled times
Several meets following condition：Low-pass signal frequency spectrum after down-sampled not aliasing.
4. the frame synchornization method of mimo system is used for according to claim 3, it is characterised in that：In step 3, described sheet
The synchronous time domain signal on ground is signal of the local synchronizing signal for generating after down-sampled, and every antenna is received and passed through
LPF and it is down-sampled after signal simultaneously cross-correlation is carried out by cross-correlator with local synchronization signal, obtain being connect per root
The cross correlation results on antenna are received, the window size of described cross-correlator is the length of original synchronous time domain signal divided by down-sampled
Multiple.
5. the frame synchornization method of mimo system is used for according to claim 4, it is characterised in that：In step 4, search peak
It is the maximum that the modulus value of cross-correlator output in the time period is found within the time of a radio frames, according to the maximum
Position in the radio frames of place positions to synchronizing signal, needs to arrange a counter after the output of cross-correlator, is used for
Each output to cross-correlator is counted, and counting cycle of counter is that total sampling number of a MIMO radio frames is removed
With down-sampled multiple, the design of counter is docked number each point of collecting mail and is positioned.
6. the frame synchornization method of mimo system is used for according to claim 5, it is characterised in that：In transmitting terminal, all antennas
The radio frames with the same MIMO frame structures are synchronously sent, identical synchronizing sequence must be sent on every antenna.
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| CN201710062976.5A CN106603131A (en) | 2017-01-31 | 2017-01-31 | Frame synchronization method for MIMO system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107144343A (en) * | 2017-07-10 | 2017-09-08 | 薛天 | Low-frequency vibration displacement transducer network-building method, system and device |
| CN108183726A (en) * | 2017-12-19 | 2018-06-19 | 南京雷行信息技术有限公司 | Multiple antenna communication synchronization detecting method based on airspace filter |
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| CN101778088A (en) * | 2010-03-12 | 2010-07-14 | 中国科学院声学研究所 | Training sequence frame timing synchronized method based on pseudo-random sequence modulation based |
| CN101841505A (en) * | 2009-03-20 | 2010-09-22 | 天际微芯(北京)科技有限公司 | Method for obtaining frame synchronization information in frame detection system with correlation characteristics |
| CN104717722A (en) * | 2015-04-01 | 2015-06-17 | 东南大学 | PSS interference elimination-based small cell discovery method in ultra dense wireless network |
| CN104767706A (en) * | 2015-04-14 | 2015-07-08 | 东莞中山大学研究院 | MIMO OFDM timing synchronization device |
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| EP1952549A1 (en) * | 2006-01-18 | 2008-08-06 | Huawei Technologies Co., Ltd. | Method and system for synchronization in a communication system |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107144343A (en) * | 2017-07-10 | 2017-09-08 | 薛天 | Low-frequency vibration displacement transducer network-building method, system and device |
| CN108183726A (en) * | 2017-12-19 | 2018-06-19 | 南京雷行信息技术有限公司 | Multiple antenna communication synchronization detecting method based on airspace filter |
| CN108183726B (en) * | 2017-12-19 | 2020-04-28 | 南京雷行信息技术有限公司 | Multi-antenna communication system synchronous detection method based on spatial filtering |
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Application publication date: 20170426 |