CN104219189A - Angle-time delay domain pilot frequency multiplexing broadband mass MIMO (multiple input multiple output) communication method - Google Patents

Abstract

The invention provides an angle-time delay domain pilot frequency multiplexing broadband mass MIMO (multiple input multiple output) communication method. The method includes that a base station wirelessly communicates with multiple subscribers on each subcarrier; a probe sequence of each subscriber is generated via a same constant modulus sequence by means of frequency domain modulation, the different subscribers send uplink probe signals on multiple subcarriers of one or more continuous OFDM (orthogonal frequency division multiplexing) symbols simultaneously, and the base station acquires angle-time delay domain two-dimensional statistics channel information according to the uplink probe signals and determines pilot frequency modulation factors of all the subscribers according to the angle-time delay domain two-dimensional statistics channel information; a pilot frequency sequence of each subscriber is generated via the same constant modulus sequence by means of frequency domain modulation, the different subscribers send uplink pilot frequency signals on the multiple subcarriers of the one or more continuous OFDM symbols simultaneously, and the base station acquires channel estimation values of a pilot frequency band and a data segment of each subscriber according to the uplink pilot frequency signals; on each subcarrier, the base station implements uplink and downlink robust transmission according to the channel estimation values and estimation error space correlation matrixes. By the method, system pilot frequency overhead can be lowered, and system frequency spectrum and power efficiency is improved.

Description

The extensive MIMO communication means in angle-time delay domain pilot frequency multiplexing broadband

Technical field

The present invention relates to and a kind ofly use the extensive mimo wireless communication method in the broadband of multiple antennas, particularly relate to the extensive mimo wireless communication method in a kind of angle-time delay domain pilot frequency multiplexing broadband.

Background technology

Base station side is equipped with the extensive mimo wireless communication technology of large-scale antenna array can the Spatial Dimension resource of deep exploitation wireless channel, compare validity and reliability that tradition small-scale MIMO technology can promote wireless communication system further, cause the extensive concern of academia and industrial quarters.Actual radio propagation channel is broad-band channel, and broad-band channel can be decomposed into multiple parallel narrow band channel by OFDM (OFDM) technology, extensive MIMO is one of development trend of wide-band mobile communication system of future generation in conjunction with OFDM.

Wireless communication system transmission quality depends on the order of accuarcy of channel parameter estimation, in order to accurately and timely obtain channel parameter estimation value, and the normal channel estimation methods adopted based on pilot aided in reality.For large-scale and multiple users MIMO-OFDM wireless communication system, have a large amount of channel parameters to need to estimate, this will cause a large amount of pilot-frequency expense.Meanwhile, linear minimum mean-squared error channel estimating needs higher dimensional matrix inversion operation, and implementation complexity is higher.The complexity of pilot-frequency expense and channel estimating becomes the bottleneck problem of extensive MIMO-OFDM radio communication.

Actual wide-band wire-less transmitting channel presents concentration of energy characteristic in angle-time delay domain, utilizes this characteristic effectively can reduce the pilot-frequency expense of system.Extensive MIMO-OFDM channel presents decorrelation characteristic in angle-time delay domain, utilizes this characteristic effectively can reduce the implementation complexity of linear minimum mean-squared error channel estimating.Based on above characteristic, The present invention gives a kind of extensive mimo wireless communication method in angle-time delay domain pilot frequency multiplexing broadband based on angle-time delay domain Two-dimensional Statistical channel information.

Summary of the invention

Technical problem: the object of this invention is to provide a kind of extensive mimo wireless communication method in angle-time delay domain pilot frequency multiplexing broadband based on angle-time delay domain Two-dimensional Statistical channel information, the pilot resources of abundant excavation angle-time delay domain, the pilot-frequency expense of saving system, reduces the complexity of channel estimating.The basic characteristics of the method are, in community, each user sends uplink detection signal on multiple subcarriers of one or more continuous OFDM symbol simultaneously, and base station side obtains the angle-time delay domain Two-dimensional Statistical channel information of each user accordingly.Each user sends uplink pilot signal on multiple subcarriers of one or more continuous OFDM symbol simultaneously, and the frequency-domain pilot sequence of different user is generated through frequency domain modulation by same sequence.Base station side utilizes the angle-time delay domain Two-dimensional Statistical channel information of each user, dynamically determines pilot modulated pattern, i.e. the frequency-domain pilot sequence modulation factor of each user.

Technical scheme: the extensive MIMO communication means in a kind of angle-time delay domain pilot frequency multiplexing broadband, is characterized in that the method is specially:

A. be applicable to the extensive mimo wireless communication system in time division duplex broadband, adopt modulating in OFDM mode, radio communication is carried out with multiple user in base station on each subcarrier simultaneously;

B. communication process is made up of multiple successive frame, and each frame signal is made up of the uplink detection signal of frame head and multiple subframe; The signal of each subframe is made up of multiple OFDM symbol, each subframe is made up of upstream data. signals section, uplink pilot signal section and downlink data signal section successively, and transmission user sends to the uplink transmission signals of base station and uplink pilot signal and base station to issue the downlink transmission signal of user respectively;

C. base station side obtains the angle-time delay domain Two-dimensional Statistical channel information of each user in community by the uplink detection of each user, and the detectable signal of different user does not require to use orthogonal resource;

In d community, each user sends uplink pilot signal on multiple subcarriers of the one or more continuous OFDM symbol of each subframe uplink pilot signal section simultaneously, the pilot frequency sequence that in same community, different user uses in the multiple continuous OFDM symbol of uplink pilot signal section is generated through frequency domain modulation by same pilot frequency sequence, and the pilot modulated factor of different user is dynamically determined according to each user perspective-time delay domain Two-dimensional Statistical channel information by base station side;

E. according to the angle-time delay domain Two-dimensional Statistical channel information of each user, the pilot signal that base station side utilizes present sub-frame uplink pilot signal section to receive is estimated the channel parameter of each user in each OFDM symbol of present sub-frame pilot signal section, and utilize the pilot modulated factor of each user, determine the channel estimation errors space correlation battle array of each user in each OFDM symbol of present sub-frame pilot signal section;

F. base station side utilizes the time domain related features of channel and the channel parameter estimation value of present sub-frame pilot signal section, implement each subscriber channel parameter Estimation in the up and each OFDM symbol of downlink data signal section of present sub-frame, and obtain the channel estimation errors space correlation battle array of each user in each OFDM symbol of data-signal section;

G. in upstream data transmission phase, each user sends upstream data. signals respectively on each subcarrier simultaneously, data-signal received by base station side stores, after base station side receives uplink pilot signal and completes each subscriber channel parameter Estimation in each OFDM symbol of present sub-frame upstream data. signals section, channel parameter estimation value and evaluated error space correlation battle array is utilized to carry out robust reception process to uplink data signals;

H. in the downlink data transmission stage, base station side sends data-signal to each user respectively on each subcarrier simultaneously, base station side utilizes each subscriber channel estimates of parameters in each OFDM symbol of present sub-frame downlink data signal section and evaluated error space correlation battle array, each subcarrier implements robust pre-coding respectively, send data-signal to each user, each user carries out reception process respectively on each subcarrier simultaneously;

I. base station side is according to the angle-time delay domain Two-dimensional Statistical channel information of each user, determines the pilot modulated pattern of each user in this community, i.e. the pilot sequence modulates factor of each user in community, and notifies each user in this community.

The extensive mimo wireless communication system in described time division duplex broadband adopts OFDM modulation mode, and base station side communicates with multiple user respectively on each subcarrier simultaneously.

Described uplink transmission signals comprises uplink detection signal, upstream data. signals and uplink pilot signal, and downlink transmission signal comprises downlink data signal.Transmitting procedure can be divided into multiple continuous print frame, and each frame signal is made up of the uplink detection signal of frame head and multiple subframe.The signal of each subframe is made up of multiple OFDM symbol, and each subframe is made up of upstream data. signals section, uplink pilot signal section and downlink data signal section successively.

Angle-time delay domain Two-dimensional Statistical the channel information acquisition of described each user is completed by the channel detection process of up link.Each user sends uplink detection signal on multiple subcarriers of the one or more continuous OFDM symbol of each frame frame head simultaneously, and the detectable signal of different user does not require to use orthogonal resource.In same community, the frequency domain detectable signal of different user is generated through frequency domain modulation by same permanent mode sequence (being called the basic detection sequence of this community), the basic detection sequence of neighbor cell requires to have good their cross correlation, and namely cross-correlation is less than the threshold value required by system.Each cell base station obtains the least-squares estimation of angle-time delay domain channel parameter in each user's present frame in community according to the uplink detection signal received, and then utilize iterative method to estimate the angle-time delay domain Two-dimensional Statistical channel information of each user in present frame, i.e. angle-time delay domain channel energy coupling matrix.

In described community, each user sends uplink pilot signal on multiple subcarriers of the one or more continuous OFDM symbol of each subframe uplink pilot signal section simultaneously.The pilot frequency sequence that in same community, different user uses is generated through frequency domain modulation by same pilot frequency sequence (being called the basic pilot frequency sequence of this community), and its modulation factor is dynamically determined according to the angle-time delay domain Two-dimensional Statistical channel information of each user in community by base station side.The basic pilot frequency sequence of neighbor cell requires to have good their cross correlation, and namely cross-correlation is less than the threshold value required by system.

The pilot signal that described base station side utilizes present sub-frame uplink pilot signal section to receive is estimated the channel parameter of each user in each OFDM symbol of present sub-frame.Base station side utilizes the angle-time delay domain Two-dimensional Statistical channel information of each user, realizes the linear minimum mean-squared error channel parameter estimation of low complex degree.First least-squares estimation is implemented to the angle-time delay domain channel parameter of each user, and then the decorrelation characteristic of foundation angle-time delay domain channel, to angle-time delay domain channel implement low complex degree by element least-squares estimation, obtain the space-frequency domain channel parameter estimation value of each user in present sub-frame pilot signal section finally by unitary transformation.Pilot signal section each subscriber channel evaluated error space correlation battle array is determined by each user perspective-time delay domain Two-dimensional Statistical channel information and pilot modulated pattern.

Described base station side utilizes the time domain related features of channel and the channel parameter estimation value of present sub-frame pilot signal section, implement each subscriber channel parameter Estimation in the up and each OFDM symbol of downlink data signal section of present sub-frame, and obtain the channel estimation errors space correlation battle array in each OFDM symbol of data-signal section.Data-signal section each subscriber channel evaluated error space correlation battle array is determined by each user perspective-time delay domain Two-dimensional Statistical channel information, channel time domain correlation properties and pilot modulated pattern.

Described in upstream data transmission phase, each user sends upstream data. signals respectively on each subcarrier simultaneously, the data-signal received by base station side stores.Receive uplink pilot signal until base station and complete in each OFDM symbol of present sub-frame upstream data. signals section after each subscriber channel parameter Estimation, on each subcarrier, utilizing channel parameter estimation value and evaluated error space correlation battle array to carry out robust reception process to uplink data signals respectively.

Described in the downlink data transmission stage, base station side sends data-signal to each user respectively on each subcarrier simultaneously.Base station utilizes each subscriber channel estimates of parameters in each OFDM symbol of present sub-frame downlink data signal section and evaluated error space correlation battle array, each subcarrier implements robust pre-coding respectively, send data-signal to each user, each user carries out reception process respectively on each subcarrier simultaneously.

Described base station side, according to the angle-time delay domain Two-dimensional Statistical channel information of each user, determines the pilot modulated pattern of each user in this community, i.e. the pilot tone modulation factor of each user in community, and notifies each user in this community.The pilot modulated factor of each user is according to angle-time delay domain Two-dimensional Statistical channel information adaptive change.

Beneficial effect: the angle based on angle-time delay domain Two-dimensional Statistical channel information provided by the invention-time delay domain pilot frequency multiplexing broadband extensive mimo wireless communication method tool has the following advantages:

1, utilize wide-band wire-less transmitting channel at the statistical nature of angle-time delay domain, fully excavate the pilot resources of angle-time delay domain, significantly reduce the pilot-frequency expense of system, and then the spectrum efficiency of elevator system and power efficiency.

2, according to the angle-time delay domain Two-dimensional Statistical channel information of each user, adaptive dynamic dispatching is carried out to pilot resources, while reduction pilot-frequency expense, ensure channel estimating performance, and the flexibility of elevator system.

3, utilize the extensive mimo channel in broadband in the decorrelation characteristic of angle-time delay domain, significantly can reduce the implementation complexity of linear minimum mean-squared error channel estimating.Utilize the channel of the time domain related features of channel to data transfer phase to estimate, improve the accuracy of data segment channel estimating further.

4, each frame upstream data. signals sent before uplink pilot signal, reduced the inaccurate impact on transmitting uplink data performance of channel estimating, improved the robustness of system.

Accompanying drawing explanation

In order to be illustrated more clearly in the technical scheme in the embodiment of the present invention, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes only shows some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, the accompanying drawing of other embodiments can also be obtained according to these accompanying drawings.

Fig. 1 is the extensive MIMO-OFDM system transfers signal frame structure schematic diagram based on angle-time delay domain Two-dimensional Statistical channel information.

Embodiment

The present invention program is understood better in order to make those skilled in the art person, below in conjunction with the accompanying drawing in the embodiment of the present invention, clear, complete description is carried out to the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, should belong to the scope of protection of the invention.

1, system configuration, signal transmission frame structure and communication process

In multi cell cellular system, each cell base station side configuration packet is containing the large-scale antenna array of the above antenna element of dozens of, and large-scale antenna array can adopt one of multiple array structures such as linear array, circular array or plate array.Suppose that the antenna element number that base station side is equipped with is M, each antenna element can adopt omnidirectional antenna or fan antenna, when each antenna element adopts omnidirectional antenna, 120 degree of fan antennas and 60 degree of fan antennas, the spacing between each antenna element can be configured to 1/2 wavelength, wavelength and 1 wavelength.Each antenna element can adopt single polarization or multi-polarization antenna.Suppose in community, to there is the user that K is equipped with single antenna, with represent user's set.User and base station communication adopt time division duplex transmission pattern, and adopt OFDM (OFDM) modulation technique of band Cyclic Prefix, subcarrier number is N _c, circulating prefix-length is N _g.

Fig. 1 is the angle-time delay domain pilot frequency multiplexing broadband extensive mimo wireless communication system transmission signal frame structural representation based on angle-time delay domain Two-dimensional Statistical channel information, wherein send to the uplink transmission signals of base station to comprise uplink detection signal, upstream data. signals and uplink pilot signal by user, send to the downlink transmission signal of user to comprise downlink data signal by base station.System transfers process can be divided into multiple continuous print frame, and each frame signal is made up of the uplink detection signal of frame head and multiple subframe.The signal of each subframe is made up of multiple OFDM symbol, and each sub-frame signals is made up of upstream data. signals section, uplink pilot signal section and downlink data signal section successively.

Under this kind of system configuration, the broadband extensive MIMO-OFDM wireless communication procedure based on angle-time delay domain Two-dimensional Statistical channel information comprises following six steps:

1) angle-time delay domain Two-dimensional Statistical channel information acquisition: the angle-time delay domain Two-dimensional Statistical channel information acquisition of each user is completed by the channel detection process of up link.Each user sends uplink detection signal on multiple subcarriers of the one or more continuous OFDM symbol of each frame frame head simultaneously, the detectable signal of different user does not require to use orthogonal resource, and the frequency domain detectable signal of each user is generated through frequency domain modulation by same permanent mode sequence.Base station obtains the least-squares estimation of each user perspective-time delay domain channel parameter in present frame according to the detectable signal received, and then utilize iterative method to estimate the angle-time delay domain Two-dimensional Statistical channel information of each user in present frame, i.e. angle-time delay domain channel energy coupling matrix.

2) pilot resources scheduling: the pilot signal transmitted while that each user being on multiple subcarriers of the one or more continuous OFDM symbol of each subframe uplink pilot signal section in community, the pilot signal of different user does not require to use orthogonal resource, and the frequency-domain pilot sequence that each user uses is generated through frequency domain modulation by same permanent mode sequence.Base station side utilizes each user perspective-time delay domain Two-dimensional Statistical channel information obtained to implement pilot resources scheduling, determines pilot modulated pattern, i.e. the uplink pilot sequence modulation factor of each user, and each user in notifying cell.

3) upstream data. signals sends: when each subframe starts, each user sends upstream data. signals on each subcarrier simultaneously.Upstream data. signals received by base station side stores, does not deal with.

4) uplink pilot signal transmission and channel parameter estimation: each user sends respective uplink pilot signal, and base station side utilizes the pilot signal received, and obtains the channel parameter estimation of each user in each OFDM symbol of present sub-frame pilot signal section.And then utilize the time domain related features of channel, obtain the channel parameter estimation of each user in present sub-frame upstream data. signals section and each OFDM symbol of downlink data signal section.Angle-time delay domain Two-dimensional Statistical the channel information of base station side according to each user and the pilot modulated factor of each user, determine the channel estimation errors space correlation battle array of each user in each OFDM symbol of pilot signal section.

5) up robust data reception process: the reception process of base station side to each user uplink data is carried out respectively on each subcarrier.Base station side utilizes channel parameter estimation in each OFDM symbol of present sub-frame upstream data. signals section of each user of obtaining and evaluated error space correlation battle array, each subcarrier respectively robust reception process is carried out to the upstream data. signals stored, obtain the estimated value that each user uplink sends data-signal, and then obtain transmission bit data flow.

6) descending robust pre-coding transfer of data: base station side is carried out on each subcarrier respectively to each user's downlink data robust pre-coding transmission.Base station side utilizes each subscriber channel parameter Estimation and evaluated error space correlation battle array in each OFDM symbol of present sub-frame downlink data signal section, calculate on each subcarrier of present sub-frame downlink data signal section and send the robust pre-coding matrix needed for data-signal to each subscriber signal, generate descending transmission signal thus, sent to each user on each subcarrier respectively by base station side simultaneously, each user carries out reception process respectively according to the signal received on each subcarrier, obtains descending transmission bit data flow.

2, angle-time delay domain Two-dimensional Statistical channel information acquisition

The acquisition of base station side to each user perspective-time delay domain Two-dimensional Statistical channel information is completed by the ascending channel detecting process of each user.Each user sends uplink detection signal on multiple subcarriers of the one or more continuous OFDM symbol of each frame frame head simultaneously, and the detectable signal of different user is generated through frequency domain modulation by same permanent mode sequence.

With g _{t, k, n, m}represent the channel parameter on t frame detection phase n-th subcarrier between user k and base station side m antenna element.Make g _{t, k, n}=[g _{t, k, n, 1}g _{t, k, n, 2}g _{t, k, n, M}] ^t, wherein subscript T represents vector transposition computing, $G_{t,k}=\left[\begin{array}{cccc}{g}_{t,k,0}& g_{t,k,1}& \·\·\·& g_{t,k,N_c-1}\end{array}\right].$ If the statistical model of Gt, k is wherein U is the fixed matrix (being called space characteristics mode matrix) depending on base station side antenna configuration mode, M _kthe matrix (each element be on the occasion of) that channel statistical parameter is formed specific to user k, each element obey independent same distribution hypothesis (each element average be zero, variance be 1), for by N _cthe front N of dimension DFT matrix _gthe matrix of row composition, ⊙ represents by element product.Claim H _{t, k}for user k is at the angle-time delay two dimensional character mode field channel matrix of t frame detection phase, be called for short angle-time delay domain channel matrix.If Ω _k=M _k⊙ M _k, when space characteristics mode matrix U is known, Ω _kbe the angle-time delay domain Two-dimensional Statistical channel information of the required user k obtained, be called angle-time delay two dimensional character mode field channel energy coupling matrix, be called for short angle-time delay domain channel energy coupling matrix.

If each user is at the Q of each frame frame head _sdindividual continuous OFDM symbol sends simultaneously, wherein Q _sdmeet KN _g≤ Q _sdn _c.With represent that in community, user k (0≤k≤K-1) is at each frame frame head q (0≤q≤Q _sd-1) detectable signal individual OFDM symbol n-th subcarrier sent.The detectable signal of user k in each frame frame head q OFDM symbol is denoted as wherein subscript T represents vector transposition computing.

The transmission signal of different user in each OFDM symbol of uplink detection stage is by same sequence x ^sdgenerate through frequency domain modulation, wherein x ^sdbe a dimension be N _cthe permanent mode sequence of × 1, meets diag{x} represents that diagonal entry is the diagonal matrix of x.For user k, its transmission signal in uplink detection stage q OFDM symbol can be generated by following formula:

Wherein for detectable signal transmitting power, represent that k is to Q _sdmodulo operation, represent the maximum integer being no more than x, V _sdfor arbitrary Q _sd× Q _sdthe unitary matrice of dimension, [V] _{a, b}represent the element being positioned at the capable b row of matrix V a, ⊙ represents that vector is by element product, pilot modulated vector expression formula for any x is as follows:

$d_x^{\mathrm{sd}}={\left[\begin{array}{cccc}\exp (-j2\mathrm{\π}\frac{0}{N_c}{N}_{g}x)& \exp (-j2\mathrm{\π}\frac{1}{N_c}{N}_{g}x)& \·\·\·& \exp (-j2\mathrm{\π}\frac{N_c-1}{N_c}{N}_{g}x)\end{array}\right]}^T---\left(2\right)$

Wherein exp (x) represents x the power operation of nature truth of a matter exp, and j is imaginary number unit, and π is circumference ratio constant.

With represent the detectable signal that base station side m root antenna arrives at t frame q detection OFDM symbol n-th received over subcarriers.If $y_{t,q,n}^{\mathrm{sd}}={\left[\begin{array}{cccc}{y}_{t,q,n,1}^{\mathrm{sd}}& y_{t,q,n,2}^{\mathrm{sd}}& \·\·\·& y_{t,q,n,M}^{\mathrm{sd}}\end{array}\right]}^T,$ $Y_{t,q}^{\mathrm{sd}}=\left[\begin{array}{cccc}{y}_{t,q,0}^{\mathrm{sd}}& y_{t,q,1}^{\mathrm{sd}}& \·\·\·& y_{t,q,N_c-1}^{\mathrm{sd}}\end{array}\right].$ Order $Y_t^{\mathrm{sd}}=\left[\begin{array}{cccc}{Y}_{t,0}^{\mathrm{sd}}& Y_{t,1}^{\mathrm{sd}}& \·\·\·& Y_{t,Q_{\mathrm{sd}}-1}^{\mathrm{sd}}\end{array}\right],$ $X_k^{\mathrm{sd}}=\left[\begin{array}{cccc}\mathrm{diag}\left\{x_{0,k}^{\mathrm{sd}}\right\}& \mathrm{diag}\left\{x_{1,k}^{\mathrm{sd}}\right\}& \·\·\·& \mathrm{diag}\{x_{Q_{\mathrm{sd}}-1,k}^{\mathrm{sd}}\end{array},\}\right],$ Wherein for the detectable signal that user k sends in each frame frame head q OFDM symbol.In the uplink detection stage of t frame, the detectable signal that base station side receives is

Wherein diag{x} represents that diagonal entry is the diagonal matrix of x, for additive white Gaussian noise matrix, the average of its each element is zero, and variance is

In t transmission frame, first by the detectable signal received obtain the estimated value of each user perspective-time delay domain channel matrix, computing formula is as follows:

${\hat{H}}_{t,k}=\frac{1}{{\mathrm{\σ}}_x^{\mathrm{sd}}{Q}_{\mathrm{sd}}}{U}^H{Y}_t^{\mathrm{sd}}{\left(F_{N_c\×N_g}^T{X}_k^{\mathrm{sd}}\right)}^H---\left(4\right)$

Wherein subscript H represents vector conjugate transpose operation.Make the angle of user k in t transmission frame-time delay domain channel energy coupling matrix Ω _kestimated value be iterative method then can be utilized to obtain the estimated value of the angle-time delay domain channel energy coupling matrix in present frame, and computing formula is as follows:

Wherein each element of subscript * representing matrix gets conjugate operation, and χ is forgetting factor, meets 0 < χ < 1.

3, pilot signal is laid and angle-time delay domain pilot frequency multiplexing

Utilize different user channel in the sparse characteristic of angle-time delay domain, different user can transmit pilot signal on identical running time-frequency resource simultaneously, thus effectively reduces the pilot-frequency expense of extensive MIMO-OFDM wireless communication system.

In community, different user sends uplink pilot signal in the one or more continuous OFDM symbol of each subframe pilot signal section simultaneously.The frequency-domain pilot sequence that in community, each user sends is generated through frequency domain modulation by a permanent mode sequence (being called the basic pilot frequency sequence of this community), and its modulation factor is dynamically determined according to the angle-time delay domain Two-dimensional Statistical channel information of each user in community by base station side.The basic pilot frequency sequence of neighbor cell requires to have good their cross correlation, and namely cross-correlation is less than the threshold value required by system.

Suppose the uplink pilot signal process of transmitting of each user in community in each subframe from t _pto t _p+ Q _tr-1 is total to Q _trindividual continuous print OFDM symbol is carried out.For user u, its pilot modulated factor is Δ _u, modulation factor is from modulation factor set in choose, it is at q (t _p≤ q≤t _p+ Q _tr-1) frequency-domain pilot sequence individual OFDM symbol sent is:

Wherein x ^trrepresent the basic pilot frequency sequence of current area, meet v _trany one Q _tr× Q _trthe unitary matrice of dimension, for emission power of pilot signal, be a N _cthe pilot sequence modulates vector of × 1, its i-th element is

Base station side, according to the angle-time delay domain Two-dimensional Statistical channel information of each user in community, is determined the modulation factor of each user's pilot frequency sequence in community, and is notified each user.Each user generates respective pilot frequency sequence, and sends uplink pilot sequence in the uplink pilot signal section of each subframe.

4, pilot signal section low complex degree two dimensional channel parameter Estimation

The base station side of up channel parameter Estimation in each community of each user is carried out respectively.In the uplink pilot signal section of each subframe, in community, all users send uplink pilot signal on multiple subcarriers of one or more continuous OFDM symbol simultaneously, and base station side obtains channel parameter estimation and the evaluated error space correlation battle array of present sub-frame pilot signal section accordingly.

In each subframe, in community, each user is from t _pto t _p+ Q _tr-1 is total to Q _trmultiple subcarriers of individual continuous print OFDM symbol send uplink pilot signal simultaneously.With represent that base station side m root antenna is at present sub-frame t _pthe pilot signal that individual OFDM symbol n-th received over subcarriers arrives, to represent between user k and base station side m antenna element t in present sub-frame _pchannel parameter on individual OFDM symbol n-th subcarrier.If $y_{t_p,n}^{\mathrm{tr}}={\left[\begin{array}{cccc}{y}_{t_p,n,1}^{\mathrm{tr}}& y_{t_p,n,2}^{\mathrm{tr}}& \&CenterDot;\&CenterDot;\&CenterDot;& y_{t_p,n,M}^{\mathrm{tr}}\end{array}\right]}^T,Y_{t_p}^{\mathrm{tr}}=\left[\begin{array}{cccc}{y}_{t_p,0}^{\mathrm{tr}}& y_{t_p,1}^{\mathrm{tr}}& \&CenterDot;\&CenterDot;\&CenterDot;& y_{t_p,N_c-1}^{\mathrm{tr}}\end{array}\right],$ $Y^{\mathrm{tr}}=\left[\begin{array}{cccc}{Y}_{t_p}^{\text{tr}}& Y_{t_p+1}^{\mathrm{tr}}& \&CenterDot;\&CenterDot;\&CenterDot;& Y_{t_p+Q_{\mathrm{tr}}-1}^{\mathrm{tr}}\end{array}\right],g_{t_p,k,n}={\left[\begin{array}{cccc}{g}_{t_p,k,n,1}& g_{t_p,k,n,2}& \&CenterDot;\&CenterDot;\&CenterDot;& g_{t_p,k,n,M}\end{array}\right]}^T,$ $G_{t_p,k}=\left[\begin{array}{cccc}{g}_{t_p,k,0}& g_{t_p,k,1}& \&CenterDot;\&CenterDot;\&CenterDot;& g_{t_p,k,N_c-1}\end{array}\right],$ $X_k^{\mathrm{tr}}=\left[\begin{array}{cccc}\mathrm{diag}\left\{x_{t_p,k}^{\mathrm{tr}}\right\}& \mathrm{diag}\left\{x_{t_p+1,k}^{\mathrm{tr}}\right\}& \&CenterDot;\&CenterDot;\&CenterDot;& \mathrm{diag}\{x_{t_p+Q_{\mathrm{tr}}-1,k}^{\mathrm{tr}}\end{array}\}\right].$ Then in the uplink pilot signal transmission phase of present sub-frame, the pilot signal that base station side receives is

Wherein Z ^trfor additive white Gaussian noise matrix, the average of its each element is zero, and variance is

Base station side utilizes the decorrelation characteristic between angle-each element of time delay formula territory channel, and base station side can realize the extensive MIMO-OFDM channel parameter estimation of linear minimum mean-squared error of low complex degree.

For the user k in current area, the least-squares estimation value first obtaining its angle-time delay domain channel parameter is as follows:

${\hat{H}}_{t_p,k}^{\mathrm{LS}}=\frac{1}{{\mathrm{\&sigma;}}_x^{\mathrm{tr}}{Q}_{\mathrm{tr}}}{U}^H{Y}_{t_p}^{\mathrm{tr}}{\left[F_{N_c\&times;N_g}^T{X}_k^{\mathrm{tr}}\right]}^H---\left(8\right)$

According to the angle-time delay domain Two-dimensional Statistical channel information of extensive MIMO-OFDM channel, the Linear Minimum Mean-Square Error Estimation of the channel parameter of its angle-time delay domain can be obtained.Because extensive MIMO-OFDM channel presents decorrelation characteristic in angle-time delay domain, can be right each element carry out Linear Minimum Mean-Square Error Estimation respectively, thus reduce implementation complexity, the estimator of its i-th row jth column element is:

Wherein $\mathrm{\&delta;}(a-b)=\left\{\begin{array}{cc}1,& a=b\\ 0,& a\&NotEqual;b\end{array}\right.,$ Ω _kfor the estimated value of the angle-time delay domain channel energy coupling matrix of user k in present frame, computing formula for arbitrary integer Δ is

Foundation the space-frequency domain channel parameter estimation value that can obtain present sub-frame uplink pilot signal section is as follows:

${\hat{G}}_{t_p,k}={U\hat{H}}_{t_p,k}^{\mathrm{MMSE}}{F}_{N_c\&times;N_g}^T---\left(11\right)$

User k is as follows in the channel estimation errors space correlation battle array of uplink pilot signal section:

$R_{{\tilde{g}}_{t_p,k}}=\mathrm{Udiag}\left\{r_{{\tilde{g}}_{t_p,k}}\right\}{U}^H---\left(12\right)$

Wherein the computing formula of i-th element is:

5, data-signal section two dimensional channel parameter Estimation

Utilize the time domain related features of present sub-frame pilot signal section channel parameter estimation value and the channel obtained, can estimate (being also called channel estimating) by channel parameter that is up to present sub-frame and downlink data signal section.For user k, suppose that base station side estimates that the channel maximum Doppler frequency offset of the user k obtained is v _k, and it is at present sub-frame uplink pilot signal section (t _pto t _p+ Q _tr-1 OFDM symbol) channel estimation value be then be positioned at present sub-frame data-signal section (t _p+ Δ _tindividual OFDM symbol) space-frequency domain channel parameter estimation value can be calculated as follows:

${\hat{G}}_{t_p+{\mathrm{\&Delta;}}_t,k}={\mathrm{\&rho;}}_k({\mathrm{\&Delta;}}_t-\frac{Q_{\mathrm{tr}}-1}{2}){\hat{G}}_{t_p,k}---\left(14\right)$

Wherein ρ _k(x)=J ₀(2 π v _kt _symx), T _symfor system OFDM symbol length, J ₀the first kind zero Bessel function of (x) to be variable be x.

User k is calculated as follows in the channel estimation errors space correlation battle array of data-signal section:

$R_{{\tilde{g}}_{t_p+{\mathrm{\&Delta;}}_t,k}}=\mathrm{Udiag}\left\{r_{{\tilde{g}}_{t_p{+\mathrm{\&Delta;}}_t,k}}\right\}{U}^H---\left(15\right)$

Wherein the computing formula of i-th element be:

6, up robust data reception

In each subframe, each user sends upstream data. signals first respectively on each subcarrier simultaneously, the signal received by base station side stores.When base station side receives uplink pilot signal and completes the channel parameter estimation of upstream data. signals section, utilize upstream data. signals section channel estimation value and channel estimation errors space correlation battle array, each subcarrier implements robust reception to uplink data respectively.

For t OFDM symbol n-th subcarrier of upstream data. signals section in each subframe, up robust data reception process is described.With represent the upstream data. signals that in community, user k sends on present sub-frame t OFDM symbol n-th subcarrier, its average is zero, variance is the transmission data-signal of each user is that it sends the data-signal obtained after information bit flows through the mapping of chnnel coding, intertexture and modulation symbol.With represent the data-signal that base station side m root antenna arrives at present frame t OFDM symbol n-th received over subcarriers, g _{t, k, n, m}represent the channel parameter on present sub-frame t OFDM symbol n-th subcarrier between user k and base station side m antenna element.

If $y_{t,n}^{\mathrm{ul}}={\left[\begin{array}{cccc}{y}_{t,n,1}^{\mathrm{ul}}& y_{t,n,2}^{\mathrm{ul}}& \&CenterDot;\&CenterDot;\&CenterDot;& y_{t,n,M}^{\mathrm{ul}}\end{array}\right]}^T,$ G _{t, k, n}=[g _{t, k, n, 1}g _{t, k, n, 2}g _{t, k, n, M}] ^t, G _{t, n}=[g _{t, 0, n}g _{t, 1, n}gt _{, K-1, n}], the upstream data. signals that then base station side receives on current sub-carrier is:

$y_{t,n}^{\mathrm{ul}}=G_{t,n}{x}_{t,n}^{\mathrm{ul}}+z_{t,n}^{\mathrm{ul}}---\left(17\right)$

Wherein for additive white Gaussian noise vector, the average of its each element is zero, and variance is

Upstream data. signals received by base station side stores, receives the uplink pilot signal of each user until base station side and after completing upstream data. signals section channel parameter estimation, estimates the upstream data. signals that each user sends.

The channel parameter estimation value of each user base station side obtained on previous OFDM symbol current sub-carrier is designated as wherein for base station side is to channel parameter g _{t, k, n}estimated value.Under average minimum mean square error criterion, on previous OFDM symbol current sub-carrier, the Robust Estimation of each user uplink data signal is calculated by following formula:

Wherein for the transmitting signal to noise ratio that each user uplink data transmits, for the channel estimation errors space correlation battle array of user k on previous OFDM symbol.Utilize each user on previous OFDM symbol current sub-carrier to send the Robust Estimation value of data-signal, through processes such as demodulation, deinterleaving and channel-decodings, each user on previous OFDM symbol current sub-carrier can be obtained and send the estimated value of message bit stream.

7, descending robust pre-coding

In the downlink data transmission stage, base station side sends data-signal to each user respectively on each subcarrier simultaneously.Utilize each user of obtaining in the channel parameter estimation value of downlink data signal section and channel estimation errors space correlation battle array, each subcarrier is implemented descending robust pre-coding transmission respectively.Descending robust pre-coding transmission can adopt average minimum mean square error criterion, makes the mean square error mean value of least mean-square error precoding transmissions within the scope of channel estimation errors minimum.

Following transmitting procedure is for the n-th subcarrier in downlink data signal section t OFDM symbol.With represent the data-signal before the precoding of base station K user's transmission in previous OFDM symbol current sub-carrier Shang Xiang community, wherein a kth element is the data-signal sent to user k, and its average is zero, variance is the transmission data-signal of each user is that it sends the data-signal obtained after information bit flows through the mapping of chnnel coding, intertexture and modulation symbol.With B _{t, n}represent the base station pre-coding matrix on previous OFDM symbol current sub-carrier, base station side actual transmission signal is owing to adopting time division duplex transmission pattern, on the same subcarrier of same OFDM symbol, down channel can be expressed as up channel G _{t, n}transposition.The Received signal strength of user side can be expressed as:

$y_{t,n}^{\mathrm{dl}}=G_{t,n}^T{B}_{t,n}{x}_{t,n}^{\mathrm{dl}}+z_{t,n}^{\mathrm{dl}}---\left(19\right)$

Wherein represent the data-signal that K user receives on current sub-carrier, wherein a kth element is the data-signal that user k receives, for additive white Gaussian noise vector, the average of its each element is zero, and variance is

Under average minimum mean square error criterion, the robust pre-coding matrix of base station side is calculated by following formula:

Wherein for base station side is to current sub-carrier up channel parameter G _{t, n}estimated value, for the average emitted signal to noise ratio of each user's downlink transfer, γ _{t, n}for base station side transmit power constraint parameter, can be calculated by following formula:

Wherein tr{.} representing matrix asks mark computing.

Each user utilizes the signal arrived at each received over subcarriers, through processes such as demodulation, deinterleaving and channel-decodings, can obtain the estimated value of the descending transmission message bit stream on each subcarrier.

8, angle-time delay domain pilot tone scheduling

Pilot tone scheduling is implemented in base station side, base station side utilizes each user perspective-time delay domain Two-dimensional Statistical channel information obtained, according to given criterion, as channel estimating mean square error sum minimum criteria, determine the user's pilot modulated pattern in community, the i.e. frequency domain modulation factor of each user's pilot frequency sequence, and each user in notifying cell.With represent the pilot modulated pattern of current area, wherein k represents Customs Assigned Number, Δ _krepresent the pilot frequency sequence frequency domain modulation factor that user k uses.

Channel estimating mean square error sum can be obtained by following formula according to the angle of each user-time delay domain Two-dimensional Statistical channel information:

Namely pilot tone based on channel estimating mean square error sum minimum criteria dispatches: search out and make ε ^trminimum pilot modulated pattern the scheduling of this pilot tone completes by exhaustive search or greedy algorithm.

The dynamic conditioning of 9, angle-extensive MIMO transmission in time delay domain pilot frequency multiplexing broadband

In each user's moving process, along with angle between base station and each user-time delay domain Two-dimensional Statistical channel information Ω _kchange, base station side dynamically implements the scheduling of aforementioned pilot tone, forms the pilot modulated pattern after upgrading, and and then implements the aforesaid extensive MIMO wireless transmission in angle-time delay domain pilot frequency multiplexing broadband based on angle-time delay domain Two-dimensional Statistical channel information.The change of channel statistic is relevant with concrete application scenarios, and its typical statistic time window is several times or the decades of times of frame length, and the acquisition of relevant channel statistical information is also carried out on larger time width.

In the embodiment that the application provides, should be understood that, disclosed method, not exceeding in the spirit and scope of the application, can realize in other way.Current embodiment is a kind of exemplary example, should as restriction, and given particular content should in no way limit the object of the application.Such as, multiple unit or assembly can in conjunction with or another system can be integrated into, or some features can be ignored, or do not perform.

The above; be only the specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; change can be expected easily or replace, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of described claim.

Claims (10)

1. the extensive MIMO communication means in angle-time delay domain pilot frequency multiplexing broadband, is characterized in that the method is specially:

A. be applicable to the extensive mimo wireless communication system in time division duplex broadband, adopt modulating in OFDM mode, radio communication is carried out with multiple user in base station on each subcarrier simultaneously;

B. communication process is made up of multiple successive frame, and each frame signal is made up of the uplink detection signal of frame head and multiple subframe; The signal of each subframe is made up of multiple OFDM symbol, each subframe is made up of upstream data. signals section, uplink pilot signal section and downlink data signal section successively, and transmission user sends to the uplink transmission signals of base station and uplink pilot signal and base station to issue the downlink transmission signal of user respectively;

C. base station side obtains the angle-time delay domain Two-dimensional Statistical channel information of each user in community by the uplink detection of each user, and the detectable signal of different user does not require to use orthogonal resource;

D. in community, each user sends uplink pilot signal on multiple subcarriers of the one or more continuous OFDM symbol of each subframe uplink pilot signal section simultaneously, the pilot frequency sequence that in same community, different user uses in the multiple continuous OFDM symbol of uplink pilot signal section is generated through frequency domain modulation by same pilot frequency sequence, and the pilot modulated factor of different user is dynamically determined according to each user perspective-time delay domain Two-dimensional Statistical channel information by base station side;

E. according to the angle-time delay domain Two-dimensional Statistical channel information of each user, the pilot signal that base station side utilizes present sub-frame uplink pilot signal section to receive is estimated the channel parameter of each user in each OFDM symbol of present sub-frame pilot signal section, and utilize the pilot modulated factor of each user, determine the channel estimation errors space correlation battle array of each user in each OFDM symbol of present sub-frame pilot signal section;

F. base station side utilizes the time domain related features of channel and the channel parameter estimation value of present sub-frame pilot signal section, implement each subscriber channel parameter Estimation in the up and each OFDM symbol of downlink data signal section of present sub-frame, and obtain the channel estimation errors space correlation battle array of each user in each OFDM symbol of data-signal section;

G. in upstream data transmission phase, each user sends upstream data. signals respectively on each subcarrier simultaneously, data-signal received by base station side stores, after base station side receives uplink pilot signal and completes each subscriber channel parameter Estimation in each OFDM symbol of present sub-frame upstream data. signals section, channel parameter estimation value and evaluated error space correlation battle array is utilized to carry out robust reception process to uplink data signals;

H. in the downlink data transmission stage, base station side sends data-signal to each user respectively on each subcarrier simultaneously, base station side utilizes each subscriber channel estimates of parameters in each OFDM symbol of present sub-frame downlink data signal section and evaluated error space correlation battle array, each subcarrier implements robust pre-coding respectively, send data-signal to each user, each user carries out reception process respectively on each subcarrier simultaneously;

I. base station side is according to the angle-time delay domain Two-dimensional Statistical channel information of each user, determines the pilot modulated pattern of each user in this community, i.e. the pilot sequence modulates factor of each user in community, and notifies each user in this community.

2. the extensive MIMO communication means in angle according to claim 1-time delay domain pilot frequency multiplexing broadband, it is characterized in that: the extensive mimo wireless communication system in described time division duplex broadband adopts OFDM modulation mode, and base station side communicates with multiple user respectively on each subcarrier simultaneously.

3. the extensive MIMO communication means in angle according to claim 1-time delay domain pilot frequency multiplexing broadband, it is characterized in that: described uplink transmission signals comprises uplink detection signal, upstream data. signals and uplink pilot signal, and downlink transmission signal comprises downlink data signal; Transmitting procedure can be divided into multiple continuous print frame, and each frame signal is made up of the uplink detection signal of frame head and multiple subframe; The signal of each subframe is made up of multiple OFDM symbol, and each subframe is made up of upstream data. signals section, uplink pilot signal section and downlink data signal section successively.

4. the extensive MIMO communication means in angle according to claim 1-time delay domain pilot frequency multiplexing broadband, is characterized in that: the angle-time delay domain Two-dimensional Statistical channel information acquisition of described each user is completed by the channel detection process of up link; Each user sends uplink detection signal on multiple subcarriers of the one or more continuous OFDM symbol of each frame frame head simultaneously, and the detectable signal of different user does not require to use orthogonal resource; In same community, the frequency domain detectable signal of different user is generated through frequency domain modulation by same permanent mode sequence (being called the basic detection sequence of this community), the basic detection sequence of neighbor cell requires to have good their cross correlation, and namely cross-correlation is less than the threshold value required by system; Each cell base station obtains the least-squares estimation of angle-time delay domain channel parameter in each user's present frame in community according to the uplink detection signal received, and then utilize iterative method to estimate the angle-time delay domain Two-dimensional Statistical channel information of each user in present frame, i.e. angle-time delay domain channel energy coupling matrix.

5. the extensive MIMO communication means in angle according to claim 1-time delay domain pilot frequency multiplexing broadband, is characterized in that: in described community, each user sends uplink pilot signal on multiple subcarriers of the one or more continuous OFDM symbol of each subframe uplink pilot signal section simultaneously; The pilot frequency sequence that in same community, different user uses is called the basic pilot frequency sequence of this community by same pilot frequency sequence, generate through frequency domain modulation, its modulation factor is dynamically determined according to the angle-time delay domain Two-dimensional Statistical channel information of each user in community by base station side; The basic pilot frequency sequence of neighbor cell requires to have good their cross correlation, and namely cross-correlation is less than the threshold value required by system.

6. the extensive MIMO communication means in angle according to claim 1-time delay domain pilot frequency multiplexing broadband, is characterized in that: the pilot signal that described base station side utilizes present sub-frame uplink pilot signal section to receive is estimated the channel parameter of each user in each OFDM symbol of present sub-frame; Base station side utilizes the angle-time delay domain Two-dimensional Statistical channel information of each user, realizes the linear minimum mean-squared error channel parameter estimation of low complex degree; First least-squares estimation is implemented to the angle-time delay domain channel parameter of each user, and then the decorrelation characteristic of foundation angle-time delay domain channel, to angle-time delay domain channel implement low complex degree by element least-squares estimation, obtain the space-frequency domain channel parameter estimation value of each user in present sub-frame pilot signal section finally by unitary transformation; Pilot signal section each subscriber channel evaluated error space correlation battle array is determined by each user perspective-time delay domain Two-dimensional Statistical channel information and pilot modulated pattern.

7. the extensive MIMO communication means in angle according to claim 1-time delay domain pilot frequency multiplexing broadband, it is characterized in that: described base station side utilizes the time domain related features of channel and the channel parameter estimation value of present sub-frame pilot signal section, implement each subscriber channel parameter Estimation in the up and each OFDM symbol of downlink data signal section of present sub-frame, and obtain the channel estimation errors space correlation battle array in each OFDM symbol of data-signal section; Data-signal section each subscriber channel evaluated error space correlation battle array is determined by each user perspective-time delay domain Two-dimensional Statistical channel information, channel time domain correlation properties and pilot modulated pattern.

8. the extensive MIMO communication means in angle according to claim 1-time delay domain pilot frequency multiplexing broadband, it is characterized in that: described in upstream data transmission phase, each user sends upstream data. signals respectively on each subcarrier simultaneously, the data-signal received by base station side stores; Receive uplink pilot signal until base station and complete in each OFDM symbol of present sub-frame upstream data. signals section after each subscriber channel parameter Estimation, on each subcarrier, utilizing channel parameter estimation value and evaluated error space correlation battle array to carry out robust reception process to uplink data signals respectively.

9. the extensive MIMO communication means in angle according to claim 1-time delay domain pilot frequency multiplexing broadband, is characterized in that: described in the downlink data transmission stage, base station side sends data-signal to each user respectively on each subcarrier simultaneously; Base station utilizes each subscriber channel estimates of parameters in each OFDM symbol of present sub-frame downlink data signal section and evaluated error space correlation battle array, each subcarrier implements robust pre-coding respectively, send data-signal to each user, each user carries out reception process respectively on each subcarrier simultaneously.

10. the extensive MIMO communication means in angle according to claim 1-time delay domain pilot frequency multiplexing broadband, it is characterized in that: described base station side is according to the angle-time delay domain Two-dimensional Statistical channel information of each user, determine the pilot modulated pattern of each user in this community, the i.e. pilot tone modulation factor of each user in community, and notify each user in this community; The pilot modulated factor of each user is according to angle-time delay domain Two-dimensional Statistical channel information adaptive change.