CN1972271B - A synchronization method of MIMO-OFDM system - Google Patents
A synchronization method of MIMO-OFDM system Download PDFInfo
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- CN1972271B CN1972271B CN2006101360989A CN200610136098A CN1972271B CN 1972271 B CN1972271 B CN 1972271B CN 2006101360989 A CN2006101360989 A CN 2006101360989A CN 200610136098 A CN200610136098 A CN 200610136098A CN 1972271 B CN1972271 B CN 1972271B
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Abstract
This invention relates to one MIMO-OFDM system simultaneous method, which comprises the following steps: a, processing relative computation by received local sequence and local ones to get relative peak and its side; b, processing filter on peak value and sides through one degree impact without limit; c, in the non integral digital sampling, the said peak value and its side are ordered to keep their position as time lag information; d, in the integral code sampling, it orders the peak value and its side and removes the sides and keeps relative peak position as time lag position to realize the simultaneous process.
Description
Technical field
The present invention relates to a kind of method for synchronous of wireless communication system, be particularly useful for multi-input multi-output-orthogonal frequency-division multiplexing (MIMO-OFDM) system.
Background technology
The OFDM technology can overcome the frequency selective fading of channel, and the MIMO technology can significantly increase power system capacity, impels the combination of OFDM technology and MIMO technology for the raising of mobile data speed and quality requirement.A significant advantage of both combinations is the OFDM technology can be a plurality of parallel flatness fading channels with the frequency-selective channel equivalence in broadband, thus the complexity of handling when greatly reducing empty that the MIMO technology brings.Therefore, MIMO-OFDM is the most promising technology in the super 3 g mobile communication system.
Synchronous and channel estimating is the key technology of MIMO-OFDM system applies research, and timing estimation can guarantee that system receiving terminal recovers transmission information in the tram, and Multipath Time Delay Estimation helps the complexity of channel estimating in the simplified system.Up to the present, be mainly two kinds at the method for MIMO-OFDM system synchronization: one distinguishes the synchronizing sequence of antenna for design, and is that carry out synchronously on the basis with this sequence; Two for only adopting many antennas to carry out synchronously at one of transmitting terminal and receiving terminal, and the method for synchronous shortcoming of visible MIMO-OFDM system mostly is based on related operation.In addition, receiving terminal generally carries out non-integral multiple chip sample to received signal, and it can cause energy leakage, in the method for synchronous behind the related operation correlation peak can correspondingly occur the expansion.If still only keep correlation peak location this moment, suitable difficulty is arranged to guaranteeing precision of channel estimation and systematic function.Take all factors into consideration above factor, it is very necessary that the method for synchronous of a kind of MIMO-OFDM of being applicable to system under non-integral multiple chip sample is provided.Good method for synchronous must guarantee high accuracy under the prerequisite of low complex degree, must possess flexibility and practicality simultaneously, has engineering using value and prospect as target.
Summary of the invention
At the problem that exists in the existing simultaneous techniques, the present invention proposes the method for synchronous of a kind of MIMO-OFDM system, described method comprises step:
(1) local training sequence and the sequence that receives are carried out related operation, obtain correlation peak and secondary lobe thereof;
(2) described correlation peak and secondary lobe thereof are carried out filtering by the single order infinite impulse response digital filter;
(3) when described MIMO-OFDM system in non-integral multiple chip sample following time, filtered described correlation peak and secondary lobe thereof are sorted, keep correlation peak and secondary lobe relevant position thereof as delay positions information;
(4) when described MIMO-OFDM system in integral multiple chip sample following time, filtered described correlation peak and secondary lobe thereof are sorted, and remove the correlation peak secondary lobe, keep correlation peak location as delay positions information, thereby realize synchronously.
Preferably, step (1) also comprises step:
After carrying out related operation, described correlation peak that obtains and secondary lobe thereof are carried out noise estimation processing, estimate to simplify noise power.
Preferably,, judge that its position is not best timing position, make that correlation peak and secondary lobe thereof are zero, to reduce follow-up operand when described correlation peak and secondary lobe thereof during less than noise power; Otherwise, keep described correlation peak and secondary lobe thereof.
Preferably, step (1) also comprises step:
The sequence that receives extracting synchronous training sequence, and is carried out related operation with described synchronous training sequence and local training sequence through separator.
Preferably, described synchronous training sequence is an OFDM symbol.
Method of the present invention is not only applicable to system under the integral multiple chip sample, and the system that is applicable to carries out the extraction of multidiameter delay information under non-integral multiple chip sample.It can provide complete time delay information to be used for channel estimating and equilibrium, further improves the performance of MIMO-OFDM system.
Description of drawings
Below in conjunction with accompanying drawing and with reference to embodiment the present invention is described, wherein:
Fig. 1 is a MIMO-OFDM system synchronization block diagram provided by the invention.
Embodiment
According to basic design of the present invention, method of the present invention may further comprise the steps:
(1) local sequence and the sequence that receives are carried out related operation, local sequence is the sequence after the synchronous training sequence identical with transmitting terminal carries out the IFFT conversion;
(2) utilizing the Noise Estimation technology to simplify noise power estimates.When correlation during less than noise power, judge that its position is not best timing position, make that correlation is zero, to reduce follow-up operand.Otherwise, keep correlation herein;
(3) utilize level and smooth each the frame correlation of first order IIR digital filtering technique, average treatment when realizing length is effectively controlled the correlation peak drift that multidiameter fading channel brings;
(4) handle correlation by switch control different modes;
When system in non-integral multiple chip sample following time, switch is selected admission passage 1, and correlation is sorted;
When system in integral multiple chip sample following time, switch is selected admission passage 2, correlation is sorted, and remove the correlation peak secondary lobe;
(5) utilize Multipath Time Delay Estimation to keep correlation peak location as delay positions information.
Wherein switch is selected to determine based on the requirement of sampling and channel estimating.
By the present invention the MIMO-OFDM system is carried out synchronously, integer and non-integer sampling time delay information can be provided, can effectively solve the Energy Leaking that non-integral multiple chip sample causes simultaneously, have flexibility and practicality concurrently, can guarantee accurate synchronization accuracy, improve the MIMO-OFDM systematic function.
Specifically, the MIMO-OFDM system synchronization method of the present invention's proposition carries out finishing function in a time slot.
Fig. 1 is a MIMO-OFDM system synchronization block diagram provided by the invention, the message processing flow of visible whole synchro system therefrom, received signal is at first passed through separator to extract synchronous training sequence, this sequence and local training sequence carry out related operation, wherein by noise estimation processing to simplify subsequent operation, make correlation through the first order IIR digital filter then, with level and smooth each frame correlation.When system in non-integral multiple chip sample following time, switch is selected admission passage 1, and correlation is sorted, and keeps correlation peak and secondary lobe relevant position thereof as delay positions information.When system in integral multiple chip sample following time, switch is selected admission passage 2, correlation is sorted, and remove the correlation peak secondary lobe, keeps correlation peak location as delay positions information.This time delay position offers channel estimating as multidiameter delay information, thereby improves systematic function.For being without loss of generality, training symbol is an OFDM symbol synchronously.
In conjunction with example to prove high efficiency of the present invention, reliability and practicality.Simulated conditions is: system bandwidth 20MRz, total number of sub-carriers is 1024, circulating prefix-length is 216, channel model is the COST207 indoor channel, can detect the footpath number is 2, and normalization multidiameter delay position is [030], and number of transmit antennas is 4, the reception antenna number is 8, and channel estimation method is a time domain LS algorithm.When receiving terminal adopts 0.875 times of chip sample, the method for synchronous that adopts the present invention to propose, bit error rate (BER) then can reach 2 * 10 at SNR 〉=4dB
-6Yet do not adopt the inventive method, promptly only the 2 footpath time delay information of estimating to obtain are offered channel estimating, BER will approach 0.5 all the time, and system can't operate as normal.
Claims (5)
1. the method for synchronous of a MIMO-OFDM system, described method comprises step:
(1) local training sequence and the sequence that receives are carried out related operation, obtain correlation peak and secondary lobe thereof;
(2) described correlation peak and secondary lobe thereof are carried out filtering by the single order infinite impulse response digital filter;
(3) when described MIMO-OFDM system is in non-integral multiple chip sample, filtered described correlation peak and secondary lobe thereof are sorted, keep correlation peak and secondary lobe relevant position thereof as delay positions information;
(4) when described MIMO-OFDM system is in the integral multiple chip sample, filtered described correlation peak and secondary lobe thereof are sorted, and remove the correlation peak secondary lobe, keep correlation peak location as delay positions information, thereby realize synchronously.
2. method according to claim 1, wherein step (1) also comprises step:
After carrying out related operation, described correlation peak that obtains and secondary lobe thereof are carried out noise estimation processing, estimate to simplify noise power.
3. method according to claim 2 when described correlation peak and secondary lobe thereof during less than noise power, judges that its position is not best timing position, makes that correlation peak and secondary lobe thereof are zero, to reduce follow-up operand; Otherwise, keep described correlation peak and secondary lobe thereof.
4. method according to claim 1, wherein step (1) also comprises step:
The sequence that receives extracting synchronous training sequence, and is carried out related operation with described synchronous training sequence and local training sequence through separator.
5. method according to claim 4, wherein said synchronous training sequence are OFDM symbols.
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| CN2006101360989A CN1972271B (en) | 2006-10-19 | 2006-10-19 | A synchronization method of MIMO-OFDM system |
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| CN1972271B true CN1972271B (en) | 2010-11-10 |
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| CN106953670A (en) * | 2017-04-01 | 2017-07-14 | 东南大学 | Up-downgoing joint Timing Synchronization Hardware Implementation based on extensive MIMO |
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| CN1455533A (en) * | 2003-04-01 | 2003-11-12 | 北京邮电大学 | Time synchronous method for multi-carrier CDMA system |
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| CN1455533A (en) * | 2003-04-01 | 2003-11-12 | 北京邮电大学 | Time synchronous method for multi-carrier CDMA system |
Non-Patent Citations (2)
| Title |
|---|
| 白洁等.MIMO-OFDM ***定时与多径时延估计.北京邮电大学学报28 5.2005,28(5),52-54. |
| 白洁等.MIMO-OFDM ***定时与多径时延估计.北京邮电大学学报28 5.2005,28(5),52-54. * |
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