CN101222301B - Method for TDD mode system implementing multi-input multi-output closed-loop transmission - Google Patents
Method for TDD mode system implementing multi-input multi-output closed-loop transmission Download PDFInfo
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- CN101222301B CN101222301B CN2007100002384A CN200710000238A CN101222301B CN 101222301 B CN101222301 B CN 101222301B CN 2007100002384 A CN2007100002384 A CN 2007100002384A CN 200710000238 A CN200710000238 A CN 200710000238A CN 101222301 B CN101222301 B CN 101222301B
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Abstract
The invention discloses a method for a time division duplex system to realize multi-input multi-output closed loop transmission which comprises the steps that: at first, an uplink sending area is determined, sequences to be sent are selected for a user terminal; after the sequences to be sent are modulated, the modulated sequences are mapped to the corresponding sending area; by adopting a multi-antenna periodic alternating sending mode, different antennas send different modulated sequences in each uplink frame; a channel estimation vector of each transmitting antenna of the user terminal to a base station antenna is determined according to the sent modulated sequences, finally to obtain an uplink channel response matrix; the parameters needed by a downlink channel response matrix and a downlink closed loop transmission are determined; the downlink transmission is made according to the parameters of the downlink closed loop transmission. Compared with the prior art, the invention reduces the signal processing requirements of the user terminals and improves the performance of the system by sending the defined sequences in the uplink transmission and estimating the channel response by the base station side.
Description
Technical field
The present invention relates to Radio Transmission Technology, relate in particular to multiple-input and multiple-output MIMO transmission technology.
Background technology
Multiple-input and multiple-output MIMO technology is a kind of Radio Transmission Technology efficiently that grew up in recent years, is meant at transmitting terminal and receiving terminal, uses a plurality of transmitting antennas and reception antenna to communicate respectively.The single output of many inputs MISO mode and the many output of single input SIMO mode based on transmit diversity and receive diversity are the special circumstances of MIMO.The MIMO technology mainly comprises smart antenna and two kinds of forms of Space Time Coding.Because the up-downgoing channel can be thought consistently in the TDD mode TDD system, so base station BS just can estimate the downlink channel response parameter according to the up channel parameter that obtains, as shown in Figure 1.If transmitting terminal has obtained down channel parameter accurately, just can in descending process, realize effective closed loop transmission.Usually, we utilize feedback the method for the channel condition information of transmitting terminal to be referred to as closed loop transmission, and corresponding with closed loop transmission is open-loop transmission, and open-loop transmission does not need to know the channel condition information of transmitting terminal.Closed loop transmission has many advantages than open-loop transmission, and the channel condition information of utilization transmitting terminal can improve the link performance of system, increases the coverage of system, improves the reliability that covers.The application of closed loop transmission mainly contains: employed wave beam forming, space division multiple access, closed-loop MIMO etc. in array antenna.
The orthogonal frequency division multiplex OFDM technology is divided into the subchannel of several quadratures to frequency spectrum at frequency domain, and the carrier wave of each subchannel is overlapped, has improved the availability of frequency spectrum.Because therefore the bandwidth relative narrower of each subchannel is flat fading to whole transmitted bandwidth signal frequency-selective channel for each sub-channel signal, equilibrium can be carried out respectively each subcarrier, has simplified receiver structure greatly.Because OFDM has availability of frequency spectrum height, balanced simple advantage, is very suitable for wired or wireless transmission at a high speed, has therefore obtained broad research.
In order to improve the performance of many antennas ofdm system, the communication system of some many antennas OFDM, can utilize the transmission known array, obtain up channel quality, selection for descending Space Time Coding pattern, and the wave beam forming of the precoding of Space Time Coding and smart antenna provides reliable basis, thereby the closed loop transmission of the many antennas of adaptive realization improves the communication quality of whole system.
People such as IHM BIN-CHUL are disclosed on January 20th, 2005, the patent No. is: the US2005157808 patent has proposed a kind of system of closed-loop MIMO, this system has comprised a device that pre-determines by use, be used to form the new receiver that pre-determines device, select the matrix that knows of the new device that pre-determines, and feed back the index of this matrix, if the number of transmitting antenna increases, the transmission of the method realization signal that the matrix of transmitter by feedback index correspondence and transmission signals multiply each other.Although the number of transmitting antenna increases to some extent, the candidate matrices of the previous device of utilization can the new candidate matrices of easy to do acquisition.In addition, this patent also for selecting best solution that a reference is provided, have very little amount of calculation, and the load of system reduces significantly.But system need store the candidate matrices that sets in advance in a large number, has increased system cost.
People such as CHAE CHAN-BYEUNG announced on June 8th, 2005, the patent No. is: the patent of EP1538772 provides a kind of approach of selecting by characteristic vector, the equipment and the method that are used for transfer of data in the MIMO mobile communication system, this method use feedback information to realize the reception or the transmission of data in the mimo system of closed loop.This method comprises the step of feedback transmission by the characteristic vector selection information of the singular value decomposition decision of channel matrix; Send characteristic vector selection information to transmitter; The characteristic vector that receives the feedback transmission is selected information and is selected Information Selection transmission data according to the characteristic vector that receives; Transferring data to of selection is mapped to a transmitting antenna less gets on, send and transmit data to receiver.Because as feedback information, according to the matrix theory principle, the characteristic vector of singular value decomposition is not unique, and this system used feedback mechanism, has increased the processing demands of user terminal according to the resultant characteristic vector of singular value decomposition in this invention.
Thereby, the place that there is defective in existing technology and haves much room for improvement.
Summary of the invention
In order to solve the problems of the technologies described above, the invention provides the method that a kind of TDD mode system is realized the multi-input multi-output closed-loop transmission, comprise the steps:
(1) determines the sending zone of up transmission sequence, be user terminal selecting sequence to be sent;
(2) modulate to sent sequence after, modulation sequence is mapped to corresponding sending zone;
(3) mode that adopts many antennas to send periodically in turn sends different modulation sequences by different antennae in each uplink frame;
(4) determine the channel estimating vector of each transmitting antenna of user terminal according to the modulation sequence that sends, finally obtain the up channel response matrix to antenna for base station;
(5) determine the downlink channel response matrix according to the up channel response matrix, determine downlink closed-loop transmission parameters needed according to the maximum signal noise ratio principle of receiving terminal;
(6) carry out downlink transfer according to the downlink closed-loop transmission parameter.
Wherein, in the described step (1), described sending zone can be determined according to the running time-frequency resource of system.
Further, in the described step (1), described sending zone can be determined adaptively according to described running time-frequency resource.
Wherein, in the described step (1), can be the mutually orthogonal sequence described to be sent of different described user terminal selecting.
Wherein, in the described step (2), the modulation system that described modulation is adopted can comprise the BPSK modulation system.
Wherein, in the described step (2), the described mapping ruler that shines upon institute's basis can comprise the mapping ruler that frequency domain is preferential.
Wherein, in the described step (5), described parameter can comprise the pre-coding matrix of closed loop multiple-input-output-system.
Wherein, in the described step (5), described parameter can comprise the antenna weights of down beam shaping.
Further, in the described step (6), described downlink transfer utilizes described weights that downlink data is weighted processing.
Compared with prior art, the present invention estimates channel response by send known array in uplink by base station side, has reduced the signal processing demand of user terminal, has improved the performance of system.
Description of drawings
Fig. 1 is a schematic diagram of estimating the mimo channel response matrix in the prior art at receiving terminal;
Fig. 2 is an embodiment of the invention schematic flow sheet;
Fig. 3 is the sequence transmission schematic diagram of mimo channel of the present invention through Mr antenna cycle;
Fig. 4 is the decomposing schematic representation that the channel response matrix of Fig. 3 is estimated;
Fig. 5 is an Application Example schematic diagram of the present invention.
Embodiment
The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.
Thinking of the present invention is under the pattern of TDD, utilize the Given information sequencal estimation SS of user terminal SS transmission and the channel response of base station BS, because the up-downgoing channel can be thought unanimity in the TDD system, therefore BS just can estimate the downlink channel response parameter according to the up channel parameter that obtains, if transmitting terminal has obtained down channel parameter accurately, just can not feed back and do not need to utilize in the effective closed loop transmission of descending realization.
If the SS end sends and still receives all is an antenna, then the present invention utilizes the transmission known array, obtains the channel parameter of SIMO, carries out effective closed loop transmission, can realize simple and effective multi-antenna closed transmission; If the SS end is a transmitting antenna, many reception antennas, then utilize SS end antenna to send the training sequence signal in turn, be equivalent to mimo system is divided into Mr SIMO system, Mr is the number of antennas of SS end, for each SIMO system, the independent estimations channel response, thus channel response matrix obtained.If bandwidth resources take it easy, then can send long known array; If the bandwidth resources anxiety then sends shorter sequence or a plurality of SS and sends orthogonal sequence.With known array send finish after, finally obtain the up channel response matrix, determine the downlink channel response matrix, and the downlink closed-loop transmission is needed as parameters such as antenna weights according to the up channel response matrix, utilize these parameters, carry out the MIMO closed loop transmission.
With reference to figure 2, below be the TDD realization MIMO of system closed loop transmission method embodiment flow process of the present invention signal, comprise the steps:
In the 1st step, user terminal SS determines the sending zone of up known transmission sequence to select suitable up known array to be sent according to the running time-frequency resource of system adaptively.
When system resource is sufficient, send long known array, realize channel estimating more accurately; When system resource is nervous, send short known array.The same moment, each known array to be sent will have good orthogonal property or stronger autocorrelation performance.Different SS selects mutually orthogonal transmission sequence.
The 2nd step, the known array of selecting adopted have very the BPSK modulation system of strong robustness and modulate, obtain modulation sequence, and modulation sequence is mapped to corresponding sending zone according to the preferential mapping ruler of frequency domain.
The 3rd goes on foot, and determines the emission mechanism of each antenna of user terminal SS, the mode that adopts many antennas to send periodically in turn, and SS sends different known modulation sequence by fixed sending zone to base station BS by different antennae in each uplink frame.
Emission mechanism is meant that the antenna of user terminal SS sends the mode of mutually orthogonal known array periodically in turn, suppose that user terminal has Mr reception antenna, need be the cycle then, send different known modulation sequence to base station BS continuous Mr uplink frame in the cycle respectively with Mr frame length.
The 4th step, in the cycle, determine the channel estimating vector of each transmitting antenna of user terminal at a plurality of antenna to antenna for base station according to the known modulation sequence that sends, finally obtain complete up channel response matrix.
User terminal SS continuous Mr uplink frame in the time after base station BS sends different modulation sequences, BS obtains Mr channel estimating vector, utilizes the vectorial formation of this Mr channel estimating channel response matrix.Also promptly the 1st frame upstream data is by first transmitting antenna transmission of SS, and the 2nd frame upstream data is sent by second transmitting antenna of SS, and the like, distribute up to Mr transmitting antenna.With reference to figure 3, the sequence that SS sends is in the time in Mr antenna cycle, by arriving each reception antenna of BS after the Channel Transmission, each reception antenna of BS calculates channel response separately respectively then, estimate that at frequency domain the channel response ratio is easier to, because distributing to the known array of user terminal SS is controlled by base station BS, can obtain to distribute to the known array of SS at the BS end, therefore what SS sent to BS all is known training sequence, can carry out channel estimating, m=1 according to R (m)=H (m) S (m)+N (m), 2, ..., Nc, wherein Nc is a number of sub carrier wave; H in the formula (m) is a channel response matrix, and R (m) is the signal of receiving on m the subcarrier, and S (m) is the signal that sends on m subcarrier, and N (m) is a noise.Fig. 4 is SS end Mr decomposing schematic representation that antenna successively send corresponding with Fig. 3.
All reception antennas of base station BS carry out channel estimating according to own received modulation sequence respectively, whole process just begins Mr uplink frame and has no idea to obtain complete channel estimate matrix, can be provided with in advance according to transmitting antenna and reception antenna number; Channel estimating vector during the Mr+1 frame can utilize the previous the 1st, 2, channel estimate matrix when Mr channel estimating vector is formed the Mr+1 frame, the channel estimating vector during the Mr+2 frame can utilize the previous the 2nd, 3, Mr, the channel estimate matrix when Mr+1 channel estimating vector formed the Mr+2 frame, and the like.Owing to need the Mr frame to constitute channel response matrix, therefore need store Mr-1 channel estimating vector of front, very little of this memory space, the one, because the reception antenna of user terminal can not be too much, be that Mr can not be too big, the Mr=2 of general user's terminal; The 2nd, behind the Mr frame, only need to upgrade last channel estimating vector and just can form needed up channel response matrix of this moment.
The 5th step, determine the downlink channel response matrix according to the up channel response matrix that obtains, determine downlink closed-loop transmission parameters needed according to the maximum signal noise ratio principle of receiving terminal, as the pre-coding matrix of closed-loop MIMO, the antenna weights of down beam shaping etc.Up channel response matrix and downlink channel response matrix transposition each other in the TDD system, because identical frequency band is used in uplink and downlink in the TDD system, can think the up-downgoing reciprocity, therefore estimate channel response at up transmission known array by base station side, replace traditional feedback mechanism, reduced the signal processing demand of user terminal.The calculating of the pre-coding matrix of closed-loop MIMO is based on the principle of receiver maximum signal to noise ratio, if the channel response matrix that finally obtains is H, the characteristic value of HHH has been represented the power division gain so, therefore select the weights W of the maximum pairing characteristic vector of characteristic value, can guarantee to obtain maximum signal to noise ratio at receiving terminal as pre-coding matrix;
In the 6th step, carry out the downlink closed-loop transmission according to the weights of pre-coding matrix.The weights W that utilization obtains is weighted processing to the downlink data in identical data zone, and each BS antenna is implemented different weights to identical subcarrier, and the then final signal that receives at j reception antenna of SS end can be expressed as
M=1 wherein, 2 ..., Nc, i=1,2 ..., Mt, j=1,2 ..., Mr, Mt are BS end number of transmit antennas; Total signal that reception antenna receives is
J=1 wherein, 2 ..., Mr.
Below realize that to send the Sounding sequence in the 802.16e standard closed loop transmission is that the present invention will be described for Application Example of the present invention.
Suppose to have 1 SS, the SS end has only 1 transmitting antenna, 2 reception antennas simultaneously, and the BS end has two transmitting antennas, sees Fig. 5.Utilize the known Sounding signal of transmission to carry out the estimation of up channel.
1. step at first determines to send the sending zone of up known array, and structure sounding sequence, uses Decimation Separability mode herein, and according to agreement, selectable Sounding motif is classified as:
011011110001011101101000111011110110111100010000100101110001011101101111
2. step to the sounding sequence in the corresponding Sounding Zone, carries out the BPSK modulation respectively, the complex signal after obtaining modulating.
Step 3., as shown in Figure 5, two antennas of SS end send the Sounding sequence after the modulation in turn.
4. step obtains channel response vector H in the time of a frame
1={ H
11(m); H
21(m) }, and then obtain H
2={ H
12(m); H
22(m) }, just obtained complete channel response matrix H in the time of two frames.After the transmission of Sounding sequence finishes, obtain complete up channel response matrix.
5. step determines the downlink channel response matrix, calculates the parameter that realizes that multi-antenna closed transmission needs.When the BS end obtains just can calculate the closed loop transmission parameters needed according to channel response matrix behind the required channel response matrix.Calculate the precoding coefficient of MIMO, as shown in Figure 5, in descending employing is transmitting terminal two transmit antennas, two reception antennas of receiving terminal, obtained the downlink channel response matrix of estimating through two up frame Sounding sequences, therefore, for each subcarrier, all there is such channel response matrix to have H (m)={ H
11(m), H
12(m); H
21(m), H
22(m) }, m=1,2 ..., Nc, Nc are number of sub carrier wave.By calculating H (m) H
H(m) eigenvalue of maximum characteristic of correspondence vector is as the best weight value W (m) of m subcarrier, and the BS end has several transmitting antennas, and the characteristic of correspondence vector just has apteryx, so obtained the best weight value of m subcarrier of the individual transmitting antenna of i (i=1,2).
6. step is carried out the downlink closed-loop transmission and is sent.The weights W that utilization obtains is weighted processing to the downlink data in descending identical data zone, and each BS antenna is implemented different weights to identical subcarrier, and the then final signal that receives at j reception antenna of SS end can be expressed as
M=1 wherein, 2 ..., Nc; I=1,2; J=1,2; N wherein
j(m) be the noise of m subcarrier on j the reception antenna.
Because the each channel estimating of BS end all is single signal, rather than as mimo system, the signal that each BS antenna obtains is the signal sum of a plurality of SS antenna transmission, therefore this method makes channel estimating become simple relatively, compare with traditional feedback mechanism, alleviate the signal processing demand of SS end, realized effective closed loop transmission, thereby improved the performance of system.
It is pointed out that above-mentioned description at Application Example of the present invention is comparatively concrete, can not therefore think the restriction to scope of patent protection of the present invention, scope of patent protection of the present invention should be as the criterion with claims.
Claims (9)
1. a TDD mode system is realized the method that multi-input multi-output closed-loop transmits, and it is characterized in that, comprises the steps:
(1) determines the sending zone of up transmission sequence, be user terminal selecting known array to be sent;
(2) after known array is modulated, obtain modulation sequence, modulation sequence is mapped to corresponding sending zone;
(3) mode that adopts many antennas to send periodically in turn sends different modulation sequence by fixed sending zone to the base station by different antennae in each uplink frame;
(4) known array of distributing to user terminal is by base stations control, and the base station end can obtain described known array; Determine the channel estimating vector of each transmitting antenna of user terminal according to the modulation sequence that sends, finally obtain the up channel response matrix to antenna for base station;
(5) determine the downlink channel response matrix according to the up channel response matrix, determine downlink closed-loop transmission parameters needed according to the maximum signal noise ratio principle of receiving terminal;
(6) carry out downlink transfer according to the downlink closed-loop transmission parameter.
2. the method for claim 1 is characterized in that, in the described step (1), described sending zone is determined according to the running time-frequency resource of system.
3. method as claimed in claim 2 is characterized in that, in the described step (1), described sending zone is determined adaptively according to described running time-frequency resource.
4. the method for claim 1 is characterized in that, in the described step (1), is the mutually orthogonal known array described to be sent of different described user terminal selecting.
5. the method for claim 1 is characterized in that, in the described step (2), the modulation system that described modulation is adopted comprises the BPSK modulation system.
6. the method for claim 1 is characterized in that, in the described step (2), the described mapping ruler that shines upon institute's basis comprises the mapping ruler that frequency domain is preferential.
7. the method for claim 1 is characterized in that, in the described step (5), described parameter comprises the pre-coding matrix of closed loop multiple-input-output-system.
8. the method for claim 1 is characterized in that, in the described step (5), described parameter comprises the antenna weights of down beam shaping.
9. method as claimed in claim 8 is characterized in that, in the described step (6), described downlink transfer utilizes described weights that downlink data is weighted processing.
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| CN101765125B (en) * | 2008-12-24 | 2012-08-15 | 电信科学技术研究院 | Method for transmitting uplink detection signal in multi-input and multi-output system |
| CN101771448B (en) * | 2008-12-31 | 2012-08-08 | 电信科学技术研究院 | Space division multiplexing and MIMO combining method and base station |
| US20120099469A1 (en) * | 2009-06-23 | 2012-04-26 | Qinglin Luo | Methods of transmitting a signal in a time division duplexing mimo system and associated apparatuses |
| CN102237923B (en) * | 2010-04-26 | 2016-03-30 | 中兴通讯股份有限公司 | A kind of method of wave beam forming, device and base station |
| CN101944981A (en) * | 2010-09-03 | 2011-01-12 | 北京大学 | Method for acquiring status information of medium- and long-term channel of communication system |
| CN102355432B (en) * | 2011-08-12 | 2014-07-02 | 福建星网锐捷网络有限公司 | Method and base station for determining wireless message transmission rate |
| CN104219189B (en) * | 2014-09-03 | 2017-08-15 | 东南大学 | The extensive MIMO communication means in angle time delay domain pilot frequency multiplexing broadband |
| CN107979551B (en) * | 2016-10-25 | 2022-04-15 | 中兴通讯股份有限公司 | Channel error acquisition method and device |
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| WO2004038988A2 (en) * | 2002-10-25 | 2004-05-06 | Qualcomm, Incorporated | Pilots for mimo communication systems |
| WO2005101690A1 (en) * | 2004-04-14 | 2005-10-27 | Utstarcom Telecom Co., Ltd. | Multiple-input multiple-output (mimo) method based on a distributed transmission source in a centralized base station system |
| CN1829114A (en) * | 2006-04-07 | 2006-09-06 | 中兴通讯股份有限公司 | Downlink and uplink transmitting method for realizing MIMO |
| CN1890895A (en) * | 2003-12-05 | 2007-01-03 | 三星电子株式会社 | Apparatus and method for transmitting data using eigenvector selection in mimo mobile communication systems |
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| WO2004038988A2 (en) * | 2002-10-25 | 2004-05-06 | Qualcomm, Incorporated | Pilots for mimo communication systems |
| CN1890895A (en) * | 2003-12-05 | 2007-01-03 | 三星电子株式会社 | Apparatus and method for transmitting data using eigenvector selection in mimo mobile communication systems |
| WO2005101690A1 (en) * | 2004-04-14 | 2005-10-27 | Utstarcom Telecom Co., Ltd. | Multiple-input multiple-output (mimo) method based on a distributed transmission source in a centralized base station system |
| CN1829114A (en) * | 2006-04-07 | 2006-09-06 | 中兴通讯股份有限公司 | Downlink and uplink transmitting method for realizing MIMO |
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