CN102195756B - Method and device for calibrating time division duplex MIMO (Multiple Input Multiple Output) system - Google Patents

Abstract

The invention provides a method and device for calibrating a time division duplex (TDD) MIMO (Multiple Input Multiple Output) system. The method comprises the following steps of: determining any one end in a base station and a user terminal as a calibrating end and determining the other end in the base station and the user terminal as a second terminal, wherein the calibrating end is provided with M antennae, the second end is provided with N antennae, and M and N are more than 1; performing channel estimation on all links from the calibrating end to the second end and performing channel estimation on all links from the second end to the calibrating end; reporting the information of all estimated links from one antenna I at the calibrating end to the second end to the calibrating end by using the second end; performing self-calibration on the M antennae by using the calibration end to obtain a self-adjusting coefficient; and determining a calibrating coefficient according to the self-adjusting coefficient and the information of all reported links form one antenna I at the calibrating end to the second end by using the calibrating end. Due to the adoption of the method and the device, the calibrating performance is approximate to that of the conventional method, and less calibrating time is consumed as comparison with the conventional method.

Description

The calibration steps of time division duplex mimo system and device

Technical field

The present invention relates to wireless communication field, espespecially a kind of calibration steps of time division duplex (TDD) mimo system and device.

Background technology

Information theory shows: under multipath wireless channels, uses the capacity that the multiple-input and multiple-output of suitable space-time code (MIMO) system can provide larger compared with SISO system.Under being operated in mimo antenna configuration, mimo system without increase in bandwidth, can be compared SISO system and promotes the rate of information throughput exponentially, thus drastically increase the availability of frequency spectrum.

Based in the mobile communication system of MIMO, send from multiple transmitting antenna while of signal.For improving transmission rate and the transmission performance of system, the technology such as space division multiplexing (SDM), Space Time Coding (STC) and space-time joint transmission can be adopted according to the difference of channel circumstance.Particularly, MIMO technology is roughly divided into two classes: transmitting/receiving diversity and spatial reuse.Wherein, diversity technique is used for overcoming channel fading.For reception diversity technology, the signal carrying identical information is sent out away by different paths, can obtain the duplicate of the multiple independent decline of data symbol, thus obtain higher reception reliability at receiving terminal.Such as, in slow Rayleigh fading channel, when system uses 1 transmit antennas, N root reception antenna, signal is sent by N number of different path; If the decline between each reception antenna is independently, the maximum diversity gain that can obtain is N.Similarly, transmit diversity techniques is also utilize the gain of mulitpath to improve the reliability of system.Such as, have in the system of M transmit antennas, N root reception antenna at one, if antenna between path gain be the Rayleigh fading of independent and uniform distribution, the maximum diversity gain that can obtain is M*N.Can find out, the number of antennas used in mimo system is more, and the diversity gain obtained is larger, and the reliability of whole system is higher.

But for the mimo system using VBLAST structure, along with number of transmit antennas object increases, the complexity exponentially of receiving terminal in input increases.Therefore, existing mimo system uses low order MIMO mostly, and also namely number of transmit antennas is less than or equal to 4.

In the conventional method, the process estimated the calibration factor of high level MIMO system as shown in Figure 1, comprises the following steps.It may be noted that in following process and any one in base station or UE is called that A holds, another is called that B holds; In other words, transmitter is called that A holds, receiver is called that B holds.

Step 101: carry out channel estimating to the link that A holds B to hold, implementation procedure is shown in Fig. 2 (a) and (b).

Suppose that, in this high level MIMO system, the number of antennas of side a and b is 8.Therefore, step 101 needs to take 8 time slots.Wherein, the operation of time slot 1 is as shown in Fig. 2 (a), and the side that transmits got to by the duplexer of the antenna 1 of A end, and make antenna 1 and the connection that transmits, all the other duplexers are unsettled.Now, antenna 1 is only had for sending signal.Received signal strength side all got to by all duplexers of B end, the signal that the antenna 1 for receiving A end sends.

Similarly, the antenna 2 held by A at time slot 2 sends signal, and all antennas of B end receive.The rest may be inferred, and the operation of time slot 8 is as shown in Fig. 2 (b), and the side that transmits got to by the duplexer of the antenna 8 of A end, and all the other duplexers are unsettled; Received signal strength side all got to by all duplexers of B end, the signal that the antenna 8 for receiving A end sends.

Step 102: carry out channel estimating to the link that B holds A to hold, implementation procedure is shown in Fig. 3 (a) and (b).

Similarly, step 102 also needs to take 8 time slots.Wherein, the operation of time slot 1 is as shown in Fig. 3 (a), and the antenna 1 making B hold sends signal, and all antennas of A end are all for receiving this signal; The operation of time slot 8 is as shown in Fig. 3 (b).

Step 103:A end reports to B end the signal that receives, and implementation procedure is shown in Fig. 4, is held calculate calibration factor (calibration factor) by B, the channel information of what now A end sent is B to the A link that this end is estimated.Certainly, this step also can be that B end is reported to A end, is held calculate calibration factor by A.

Can find out, in (8, a 8) system, performing step 101 needs 8 time slots, and step 102 needs 8 time slots, and step 103 needs 8 time slots.That is, according to the method for prior art, altogether need 24 time slots, just can estimate all calibration factors.Because the number of antennas of high level MIMO system is comparatively large, the alignment time relatively also can be long.But in the mobile communication system in future, the use of high level MIMO system will be one of important research contents.How to reduce the alignment time in mimo system (especially high level MIMO system), become a problem needing to solve.

Summary of the invention

In view of this, the present invention proposes the calibration steps in a kind of time division duplex (TDD) multiple-input and multiple-output (MIMO) system and device, while calibration performance is close to conventional method, spend the alignment time fewer than conventional method.

For achieving the above object, technical scheme of the present invention is specifically achieved in that

A calibration steps for time division duplex mimo system, comprising:

Either end in base station and user terminal is defined as calibration terminal, the other end in base station and user terminal is defined as the second end, described calibration terminal is provided with M root antenna, and described second end is provided with N root antenna, and wherein M and N is all greater than 1;

To all links of the second end, channel estimating is carried out to calibration terminal, and to all links of calibration terminal, channel estimating is carried out to the second end;

A wherein antenna I of the calibration terminal that the second end is estimated gives described calibration terminal to the information reporting of all links of the second end;

Calibration terminal carries out self calibration to described M root antenna, obtains self-adjusting coefficient;

Described calibration terminal to the channel information of all links of the second end, determines calibration factor according to described self-adjusting coefficient, the wherein antenna I of the described calibration terminal reported to the channel information of all links of calibration terminal and the second end for the second end that estimates to obtain.

The described described M root antenna to calibration terminal carries out self calibration, obtains self-adjusting coefficient and comprises:

The switch of antenna i in calibration terminal is connected to the side that transmits, the switch of antenna k in calibration terminal is connected to Received signal strength side, after sending test signal from the side that transmits of antenna i, receive the first signal at the Received signal strength side joint of antenna k;

The switch of antenna k in calibration terminal is connected to the side that transmits, the switch of antenna i in calibration terminal is connected to Received signal strength side, after sending described test signal from the side that transmits of antenna k, receive secondary signal at the Received signal strength side joint of antenna i;

First signal and secondary signal are compared, obtains the self-adjusting coefficient between antenna k and antenna i ${\mathrm{\β}}_{k,i}=\frac{R_k{T}_i}{T_k{R}_i};$

Wherein, i=1 ..., M; K=1 ..., M and i ≠ k; R _ifor the reception coefficient of antenna i, T _ifor the emission ratio of antenna i; R _kfor the reception coefficient of antenna k, T _kfor the emission ratio of antenna k.

Described calibration terminal carries out the self calibration between described M root antenna after powering.

The described described M root antenna to calibration terminal carries out self calibration, obtains self-adjusting coefficient and comprises:

When carrying out channel estimating to the antenna i of calibration terminal to all links of the second end, the switch of antenna i in calibration terminal is connected to the side that transmits, and in calibration terminal, Signal reception is carried out in the Received signal strength side of antenna k, obtains the first signal;

When carrying out channel estimating to the antenna k of calibration terminal to all links of the second end, the switch of antenna k in calibration terminal is connected to the side that transmits, and in calibration terminal, Signal reception is carried out in the Received signal strength side of antenna i, obtains secondary signal;

First signal and secondary signal are compared, obtains the self-adjusting coefficient between antenna k and antenna i ${\mathrm{\β}}_{k,i}=\frac{R_k{T}_i}{T_k{R}_i};$

Wherein, i=1 ..., M; K=1 ..., M and i ≠ k; R _ifor the reception coefficient of antenna i, T _ifor the emission ratio of antenna i; R _kfor the reception coefficient of antenna k, T _kfor the emission ratio of antenna k.

A wherein antenna I of the calibration terminal that described second end is estimated comprises to described calibration terminal to the channel information reporting of all links of the second end:

Second end is according to formula determine that antenna I is the most reliable antenna of calibration terminal, and give described calibration terminal by this most reliable antenna to the channel information reporting of all links of the second end;

Wherein, described h _eff(i, j) is the channel information of the link of antenna j from the antenna i of calibration terminal to the second end, i=1 ..., M; J=1 ..., N.

The described described M root antenna to calibration terminal carries out self calibration, obtains self-adjusting coefficient and comprises:

The switch of antenna I in calibration terminal is connected to the side that transmits, the switch of antenna k in calibration terminal is connected to Received signal strength side, after sending test signal from the side that transmits of antenna I, receive the first signal at the Received signal strength side joint of antenna k;

The switch of antenna k in calibration terminal is connected to the side that transmits, the switch of antenna i in calibration terminal is connected to Received signal strength side, after sending described test signal from the side that transmits of antenna k, receive secondary signal at the Received signal strength side joint of antenna I;

First signal and secondary signal are compared, obtains the self-adjusting coefficient between antenna k and antenna I ${\mathrm{\β}}_{k,i}=\frac{R_k{T}_I}{T_k{R}_I};$

Wherein, k=1 ..., M and k ≠ I; R _ifor the reception coefficient of antenna I, T _ifor the emission ratio of antenna I; R _kfor the reception coefficient of antenna k, T _kfor the emission ratio of antenna k.

The described described M root antenna to calibration terminal carries out self calibration, obtains self-adjusting coefficient and comprises:

When carrying out channel estimating to the antenna I of calibration terminal to all links of the second end, the switch of antenna I in calibration terminal is connected to the side that transmits, and in calibration terminal, Signal reception is carried out in the Received signal strength side of antenna k, obtains the first signal;

When carrying out channel estimating to the antenna k of calibration terminal to all links of the second end, the switch of antenna k in calibration terminal is connected to the side that transmits, and in calibration terminal, Signal reception is carried out in the Received signal strength side of antenna I, obtains secondary signal;

First signal and secondary signal are compared, obtains the self-adjusting coefficient between antenna k and antenna I ${\mathrm{\β}}_{k,i}=\frac{R_k{T}_I}{T_k{R}_I};$

Wherein, k=1 ..., M and k ≠ I; R _ifor the reception coefficient of antenna I, T _ifor the emission ratio of antenna I; R _kfor the reception coefficient of antenna k, T _kfor the emission ratio of antenna k.

Described calibration terminal to the channel information of all links of the second end, determines that calibration factor comprises according to described self-adjusting coefficient, the wherein antenna I of the described calibration terminal reported to the channel information of all links of calibration terminal and the second end for the second end that estimates to obtain:

Calibration terminal is according to for the channel information of the second end to all links of calibration terminal, and a wherein antenna I of the described calibration terminal of the second end report, to the channel information of all links of the second end, determines the calibration factor α relevant with antenna I _i,j, wherein j=1 ..., N;

Calibration terminal is according to formula α _k,j=β _k,Iα _i,j, determine the calibration factor relevant with antenna k, wherein k=1 ..., M and k ≠ I.

For a base station for time division duplex mimo system, comprising:

Channel estimating unit, for carrying out channel estimating to user terminal to all links of this base station;

Self calibration unit, for carrying out self calibration to the M root antenna of self, obtains self-adjusting coefficient;

Calibration factor determining unit, for the channel information of the wherein antenna I to all links of described user terminal that receive this base station of described user terminal report, and provide according to this channel information, described channel estimating unit determine calibration factor for described user terminal to the channel information of all links of this base station and described self-adjusting coefficient.

Described self calibration unit comprises:

Test signal transceiver module, for the switch of antenna i in this base station is connected to the side that transmits, the switch of antenna k in this base station is connected to Received signal strength side, and the side that transmits of control antenna i sends test signal, and receives the first signal at the Received signal strength side joint of antenna k; Further, for the switch of antenna k in this base station is connected to the side that transmits, the switch of antenna i in this base station is connected to Received signal strength side, and the side that transmits of control antenna k sends described test signal, and receives secondary signal at the Received signal strength side joint of antenna i;

Self-adjusting Coefficient generation module, for the first signal and secondary signal being compared, obtains the self-adjusting coefficient between antenna k and antenna i wherein i=1 ..., M; K=1 ..., M and i ≠ k; R _ifor the reception coefficient of antenna i, T _ifor the emission ratio of antenna i; R _kfor the reception coefficient of antenna k, T _kfor the emission ratio of antenna k.

Described self calibration unit comprises:

Test signal transceiver module, for when carrying out channel estimating to the antenna i of this base station to all links of user terminal, in this base station, Signal reception is carried out in the Received signal strength side of antenna k, obtains the first signal; Further, for when carrying out channel estimating to the antenna k of this base station to all links of user terminal, in this base station, Signal reception is carried out in the Received signal strength side of antenna i, obtains secondary signal;

Self-adjusting Coefficient generation module, for the first signal and secondary signal being compared, obtains the self-adjusting coefficient between antenna k and antenna i wherein i=1 ..., M; K=1 ..., M and i ≠ k; R _ifor the reception coefficient of antenna i, T _ifor the emission ratio of antenna i; R _kfor the reception coefficient of antenna k, T _kfor the emission ratio of antenna k.

Described calibration factor determining unit is used for:

According to wherein antenna I of this base station of the described user terminal report received channel information to all links of described user terminal, and described channel estimating unit provide to the channel information of user terminal to all links of this base station, determine the calibration factor α relevant with antenna I _i,j, wherein j=1 ..., N;

And according to formula α _k,j=β _k,Iα _i,j, determine the calibration factor relevant with antenna k, wherein k=1 ..., M and k ≠ I.

For a user terminal for time division duplex mimo system, comprising:

Channel estimating unit, for carrying out channel estimating to base station to all links of this user terminal;

Self calibration unit, for carrying out self calibration to the M root antenna of self, obtains self-adjusting coefficient;

Calibration factor determining unit, for the channel information of the wherein antenna I to all links of described base station that receive this user terminal of described base station repeats, and provide according to this channel information, described channel estimating unit determine calibration factor for described base station to the channel information of all links of this user terminal and described self-adjusting coefficient.

Accompanying drawing explanation

Fig. 1 is the method flow diagram realizing in the mimo system of prior art calibrating;

Fig. 2 (a) and (b) realize schematic diagram for A to B channel estimating in prior art;

Fig. 3 (a) and (b) realize schematic diagram for B to A channel estimating in prior art;

Fig. 4 be in prior art A report to B realize schematic diagram;

Fig. 5 is the method flow diagram realizing in mimo systems in one embodiment of the invention calibrating;

Fig. 6 be in one embodiment of the invention B report to A realize schematic diagram;

Fig. 7 (a) and (b) are method of the present invention and the conventional method Performance comparision schematic diagram in channel estimating;

Fig. 8 is method of the present invention and the Performance comparision schematic diagram of conventional method in the error rate.

Embodiment

For making object of the present invention, technical scheme and advantage clearly understand, to develop simultaneously embodiment referring to accompanying drawing, the present invention is described in more detail.

The system model set in the following description is: receiving terminal has N root antenna, and transmitting terminal also has M root antenna.Wherein, transmitting terminal can be base station (eNB), also can be user terminal (UE).When transmitting terminal is base station, receiving terminal is UE; When transmitting terminal is UE, receiving terminal is base station.Because between base station and UE, the transmission of signal is two-way, existing upward signal from UE to base station, also has the downstream signal from base station to UE, any one in base station or UE can be called that A holds, another is called that B holds.It should be noted that, the number of antennas of receiving terminal and transmitting terminal can be arbitrary, and the number of antennas of the number of antennas of receiving terminal and transmitting terminal is uncorrelated, and such as receiving terminal only arranges 2 antennas, and transmitting terminal can arrange 4 antennas.

Correspondingly, from the signal y that A holds B to hold _aBas shown in formula (1), from the signal y that B holds A to hold _bAas shown in formula (2).

y _AB＝R _BHT _As+n (1)

y _BA＝R _AHT _Bs+n (2)

Wherein, H represents N × M channel matrix, R and T represents respectively and receive coefficient matrix and emission ratio matrix, wherein R _brepresent the reception coefficient matrix of B end, R _arepresent the reception coefficient matrix of A end;

The symbolic vector that behalf is launched, n represents white Gaussian noise vector, and y represents the signal vector that receiving terminal receives.

Particularly:

In mimo systems, efficient channel parameter is defined as wherein i=1 ..., M; J=1 ..., N.

Further, in time division duplex mimo system, because up-downgoing channel uses same frequency, different time slots, therefore its up-downgoing channel can be thought symmetrical.But, in actual applications, by a lot of device, such as amplifier, filter etc., thus its linear characteristic can be destroyed in the process of signal from base band to radio frequency, produce nonlinearity erron, affect the symmetry of up-downgoing channel.This nonlinearity erron can be considered as stochastic variable, produces and relatively fixing when starting shooting, and general only occurs changing when significantly changing in temperature.Therefore, as long as calibrate for error before communicating, obtain calibration factor, still can utilize the feature of TDD system channel symmetry.Generally, this calibration factor all can not change in for a long time.

That is, by being mimo system calibration, the following ratio receiving coefficient and emission ratio is obtained, that is:

wherein i=1 ..., M; J=1 ..., N

Just the efficient channel parameter of a link can known after, according to calibration factor α _i,jobtain backward channel parameter also namely:

i＝1,...,M；j＝1,...,N

Consider the feature of TDD system, embodiments of the invention propose a kind of calibration steps of improvement, to improve calibration speed, reduce the alignment time, detailed process is shown in Fig. 5.

Step 500:A holds the calibration carried out between self many antenna, obtains self-adjusting coefficient (self-adjustment factor).

In a specific implementation of the present invention, the process that A end is obtained from regulation coefficient is as follows:

Held by A the switch of antenna i to get to the side that transmits, held by A the switch of antenna k to get to Received signal strength side.Like this, from the signal that the Tx of antenna i sends, can receive at the Rx side joint of antenna k, be designated as S1.

Held by A the switch of antenna k to get to the side that transmits, held by A the switch of antenna i to get to Received signal strength side.Like this, from the signal that the Tx of antenna k sends, can receive at the Rx side joint of antenna i, be designated as S2.

Suppose that the test signal that the Tx of the signal that the Tx of antenna i sends and antenna k sends is S, then $S_1=S*R_k^A{T}_i^A,S_2=S*T_k^A{R}_i^A,$ Obtain ${\mathrm{\β}}_{k,i}^A=\frac{R_k^A{T}_i^A}{T_k^A{R}_i^A}.$ Wherein, i=1 ..., M; K=1 ..., M and i ≠ k.It may be noted that in this specific implementation, all duplexers of B end are all in unsettled.

In another specific implementation of the present invention, can the switch of antenna i be held to get to the side that transmits by A in step 501, while holding all antennas to send signal to B, carry out Signal reception (now the switch of the every other antenna of A end is unsettled) in the Received signal strength side of the every other antenna of A end, thus calculate self-adjusting coefficient

Step 501: the channel estimating of link A to B, this step is with step 101.Particularly, time slot 1 obtains (j=1 ..., N), time slot 2 obtains (j=1 ..., N), the rest may be inferred.

Step 502: the channel estimating of link B to A, this step is with step 102.Particularly, time slot 1 obtains (i=1 ..., M), time slot 2 obtains (i=1 ..., M), the rest may be inferred.

The signal holding a wherein antenna (being set to antenna I) from A that step 503:B end receives to the report of A end, is held according to the self-adjusting coefficient obtained in step 500 by A, calculates all calibration factors.Be specially:

5031:B end selects the antenna with most high reliability by training, such as according to formula determine antenna I.Certainly, B end can carry out the selection of most reliable antenna, but selects any antenna I and report its signal holding antenna I from A received.

5032:A end, according to the signal of B end report and the channel estimating of self, determines the calibration factor of antenna I suppose that B end is that A holds the signal of antenna 2 to the report of A end, namely (j=1 ..., N), then basis can calculate and hold with A the calibration factor that antenna 2 is relevant.

5033:A holds the calibration factor that basis is relevant with antenna I (j=1 ..., N) and self-adjusting coefficient calculate other calibration factors α _k,j(k=1 ..., M and k ≠ I).

${\mathrm{\α}}_{k,j}=\frac{R_k^A{T}_j^B}{T_k^A{R}_j^B}=\frac{R_k^A{T}_I^A}{T_k^A{R}_I^A}\·\frac{R_I^A{T}_j^B}{T_I^A{R}_j^B}={\mathrm{\β}}_{k,I}^A\·{\mathrm{\α}}_{I,j}$

It may be noted that, the time of implementation of step 500 is comparatively flexible, such as can perform when starting shooting, also can perform with step 501 simultaneously, also can A termination perform after receiving the report of B end in step 503, as long as obtain self-adjusting coefficient before calculating calibration factor in step 503.Further, can by traversal obtain the self-adjusting coefficient that A holds all antennas, also can in step 503 A end determine B end selected by antenna I after, only calculate β _k,I.Further, i and k is used in reference to any antenna of calibration terminal, there is certain scope (such as 1-M); I is used in reference to the specific antenna of calibration terminal, the second end report be exactly the information of antenna I.J is used in reference to any antenna of the second end, has certain scope (such as 1-N).

Still with (8,8) system for example, because step 500 is the self calibration communication carried out at local terminal, therefore call duration time cost negligible (utilizing the short period to carry out self calibration after such as mobile phone power-on).Step 501 needs 8 time slots, and step 502 needs 8 time slots, and the report of step 503 needs 1 time slot (see Fig. 6).Therefore, as long as 17 time slots just can estimate all calibration factors altogether.Can find out, reporting step has saved the time of 87.5% compared with conventional method (see Fig. 4).

Below provide embodiments of the invention and the simulation curve of conventional method on Performance comparision.Wherein, what Fig. 7 (a) and Fig. 7 (b) compared is Minimum Mean Square Error of Channel Estimation (Minimum-Mean-Squared-Error, MMSE) performance.Particularly, Fig. 7 (a) is it is considered that the situation of slight error, and namely time delay is 0.1 symbol period, phase deviation is 2 degree, range error is 1%; Fig. 7 (b) is it is considered that the situation of the worst error, and namely time delay is 0.5 symbol period, phase deviation is 20 degree, range error is 10%.What Fig. 8 compared is the error rate (Bit error rate, BER) performance.

Find out from simulation result, the calibration steps that the embodiment of the present invention provides not only realizes simply, on the alignment time, has very large advantage, and is more or less the same with conventional method in performance.

Further, The embodiment provides a kind of base station for time division duplex mimo system, comprising:

Channel estimating unit, for carrying out channel estimating to user terminal to all links of this base station;

Self calibration unit, for carrying out self calibration to the M root antenna of self, obtains self-adjusting coefficient;

Calibration factor determining unit, for the information of the wherein antenna I to all links of described user terminal that receive this base station of described user terminal report, and determines calibration factor according to this link information and described self-adjusting coefficient.

Described self calibration unit comprises:

Test signal transceiver module, for the switch of antenna i in this base station is connected to the side that transmits, the switch of antenna k in this base station is connected to Received signal strength side, and the side that transmits of control antenna i sends test signal, and receives the first signal at the Received signal strength side joint of antenna k; Further, for the switch of antenna k in this base station is connected to the side that transmits, the switch of antenna i in this base station is connected to Received signal strength side, and the side that transmits of control antenna k sends described test signal, and receives secondary signal at the Received signal strength side joint of antenna i;

Self-adjusting Coefficient generation module, for the first signal and secondary signal being compared, obtains the self-adjusting coefficient between antenna k and antenna i wherein i=1 ..., M; K=1 ..., M and i ≠ k.

Described self calibration unit comprises:

Test signal transceiver module, for when carrying out channel estimating to the antenna i of this base station to all links of user terminal, in this base station, Signal reception is carried out in the Received signal strength side of antenna k, obtains the first signal; Further, for when carrying out channel estimating to the antenna k of this base station to all links of user terminal, in this base station, Signal reception is carried out in the Received signal strength side of antenna i, obtains secondary signal;

Self-adjusting Coefficient generation module, for the first signal and secondary signal being compared, obtains the self-adjusting coefficient between antenna k and antenna i wherein i=1 ..., M; K=1 ..., M and i ≠ k.

Described calibration factor determining unit is used for:

According to wherein antenna I of this base station of the described user terminal report received information to all links of described user terminal, and described channel estimating unit provide to the channel estimating of user terminal to all links of this base station, determine the calibration factor α relevant with antenna I _i,j, wherein j=1 ..., N;

And according to formula α _k,j=β _k,Iα _i,j, determine the calibration factor relevant with antenna k, wherein k=1 ..., M and k ≠ I.

Further, The embodiment provides a kind of user terminal for time division duplex mimo system, comprising:

Channel estimating unit, for carrying out channel estimating to base station to all links of this user terminal;

Self calibration unit, for carrying out self calibration to the M root antenna of self, obtains self-adjusting coefficient;

Calibration factor determining unit, for the information of the wherein antenna I to all links of described base station that receive this user terminal of described base station repeats, and determines calibration factor according to this link information and described self-adjusting coefficient.

It may be noted that the either end in user terminal and base station can as calibration terminal.When user terminal is as calibration terminal, its internal structure (such as self calibration unit and calibration factor determining unit) and base station similar as internal structure during calibration terminal.Difference is, carries out information interaction as the user terminal needs of calibration terminal and the base station as the second end.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment made, equivalent replacement, improvement etc., all should be included within the scope of protection of the invention.

Claims (13)

1. a calibration steps for time division duplex mimo system, is characterized in that, comprising:

Either end in base station and user terminal is defined as calibration terminal, the other end in base station and user terminal is defined as the second end, described calibration terminal is provided with M root antenna, and described second end is provided with N root antenna, and wherein M and N is all greater than 1;

To all links of the second end, channel estimating is carried out to calibration terminal, and to all links of calibration terminal, channel estimating is carried out to the second end;

A wherein antenna I of the calibration terminal that the second end is estimated gives described calibration terminal to the channel information reporting of all links of the second end;

Calibration terminal carries out self calibration to described M root antenna, obtains self-adjusting coefficient;

Described calibration terminal to the channel information of all links of the second end, determines calibration factor according to described self-adjusting coefficient, the wherein antenna I of the described calibration terminal reported to the channel information of all links of calibration terminal and the second end for the second end that estimates to obtain.

2. method according to claim 1, is characterized in that, the described described M root antenna to calibration terminal carries out self calibration, obtains self-adjusting coefficient and comprises:

The switch of antenna i in calibration terminal is connected to the side that transmits, the switch of antenna k in calibration terminal is connected to Received signal strength side, after sending test signal from the side that transmits of antenna i, receive the first signal at the Received signal strength side joint of antenna k;

The switch of antenna k in calibration terminal is connected to the side that transmits, the switch of antenna i in calibration terminal is connected to Received signal strength side, after sending described test signal from the side that transmits of antenna k, receive secondary signal at the Received signal strength side joint of antenna i;

First signal and secondary signal are compared, obtains the self-adjusting coefficient between antenna k and antenna i ${\mathrm{\β}}_{k,i}=\frac{R_k{T}_i}{T_k{R}_i};$

Wherein, i=1 ..., M; K=1 ..., M and i ≠ k; R _ifor the reception coefficient of antenna i, T _ifor the emission ratio of antenna i; R _kfor the reception coefficient of antenna k, T _kfor the emission ratio of antenna k.

3. method according to claim 2, is characterized in that, described calibration terminal carries out the self calibration between described M root antenna after powering.

4. method according to claim 1, is characterized in that, the described described M root antenna to calibration terminal carries out self calibration, obtains self-adjusting coefficient and comprises:

When carrying out channel estimating to the antenna i of calibration terminal to all links of the second end, the switch of antenna i in calibration terminal is connected to the side that transmits, and in calibration terminal, Signal reception is carried out in the Received signal strength side of antenna k, obtains the first signal;

When carrying out channel estimating to the antenna k of calibration terminal to all links of the second end, the switch of antenna k in calibration terminal is connected to the side that transmits, and in calibration terminal, Signal reception is carried out in the Received signal strength side of antenna i, obtains secondary signal;

First signal and secondary signal are compared, obtains the self-adjusting coefficient between antenna k and antenna i ${\mathrm{\β}}_{k,i}=\frac{R_k{T}_i}{T_k{R}_i};$

Wherein, i=1 ..., M; K=1 ..., M and i ≠ k; R _ifor the reception coefficient of antenna i, T _ifor the emission ratio of antenna i; R _kfor the reception coefficient of antenna k, T _kfor the emission ratio of antenna k.

5. method according to claim 1, is characterized in that, a wherein antenna I of the calibration terminal that described second end is estimated comprises to described calibration terminal to the channel information reporting of all links of the second end:

Second end is according to formula determine that antenna I is the most reliable antenna of calibration terminal, and give described calibration terminal by this most reliable antenna to the channel information reporting of all links of the second end;

Wherein, described h _eff(i, j) is the channel information of the link of antenna j from the antenna i of calibration terminal to the second end, i=1 ..., M; J=1 ..., N.

6. method according to claim 1 or 5, it is characterized in that, the described described M root antenna to calibration terminal carries out self calibration, obtains self-adjusting coefficient and comprises:

The switch of antenna I in calibration terminal is connected to the side that transmits, the switch of antenna k in calibration terminal is connected to Received signal strength side, after sending test signal from the side that transmits of antenna I, receive the first signal at the Received signal strength side joint of antenna k;

The switch of antenna k in calibration terminal is connected to the side that transmits, the switch of antenna i in calibration terminal is connected to Received signal strength side, after sending described test signal from the side that transmits of antenna k, receive secondary signal at the Received signal strength side joint of antenna I;

First signal and secondary signal are compared, obtains the self-adjusting coefficient between antenna k and antenna I ${\mathrm{\β}}_{k,I}=\frac{R_k{T}_I}{T_k{R}_I};$

Wherein, k=1 ..., M and k ≠ I; R _ifor the reception coefficient of antenna I, T _ifor the emission ratio of antenna I; R _kfor the reception coefficient of antenna k, T _kfor the emission ratio of antenna k.

7. method according to claim 1 or 5, it is characterized in that, the described described M root antenna to calibration terminal carries out self calibration, obtains self-adjusting coefficient and comprises:

When carrying out channel estimating to the antenna I of calibration terminal to all links of the second end, the switch of antenna I in calibration terminal is connected to the side that transmits, and in calibration terminal, Signal reception is carried out in the Received signal strength side of antenna k, obtains the first signal;

When carrying out channel estimating to the antenna k of calibration terminal to all links of the second end, the switch of antenna k in calibration terminal is connected to the side that transmits, and in calibration terminal, Signal reception is carried out in the Received signal strength side of antenna I, obtains secondary signal;

First signal and secondary signal are compared, obtains the self-adjusting coefficient between antenna k and antenna I ${\mathrm{\β}}_{k,I}=\frac{R_k{T}_I}{T_k{R}_I};$

Wherein, k=1 ..., M and k ≠ I; R _ifor the reception coefficient of antenna I, T _ifor the emission ratio of antenna I; R _kfor the reception coefficient of antenna k, T _kfor the emission ratio of antenna k.

8. the method according to any one of claim 2-4, it is characterized in that, described calibration terminal to the channel information of all links of the second end, determines that calibration factor comprises according to described self-adjusting coefficient, the wherein antenna I of the described calibration terminal reported to the channel information of all links of calibration terminal and the second end for the second end that estimates to obtain:

Calibration terminal is according to for the channel information of the second end to all links of calibration terminal, and a wherein antenna I of the described calibration terminal of the second end report, to the channel information of all links of the second end, determines the calibration factor α relevant with antenna I _i,j, wherein j=1 ..., N;

Calibration terminal is according to formula α _k,j=β _k,Iα _i,j, determine the calibration factor relevant with antenna k, wherein k=1 ..., M and k ≠ I.

9. for a base station for time division duplex mimo system, it is characterized in that, comprising:

Channel estimating unit, for carrying out channel estimating to user terminal to all links of this base station;

Self calibration unit, for carrying out self calibration to the M root antenna of self, obtains self-adjusting coefficient;

Calibration factor determining unit, for the channel information of the wherein antenna I to all links of described user terminal that receive this base station of described user terminal report, and provide according to this channel information, described channel estimating unit determine calibration factor for described user terminal to the channel information of all links of this base station and described self-adjusting coefficient.

10. base station according to claim 9, is characterized in that, described self calibration unit comprises:

Test signal transceiver module, for the switch of antenna i in this base station is connected to the side that transmits, the switch of antenna k in this base station is connected to Received signal strength side, and the side that transmits of control antenna i sends test signal, and receives the first signal at the Received signal strength side joint of antenna k; Further, for the switch of antenna k in this base station is connected to the side that transmits, the switch of antenna i in this base station is connected to Received signal strength side, and the side that transmits of control antenna k sends described test signal, and receives secondary signal at the Received signal strength side joint of antenna i;

Self-adjusting Coefficient generation module, for the first signal and secondary signal being compared, obtains the self-adjusting coefficient between antenna k and antenna i wherein i=1 ..., M; K=1 ..., M and i ≠ k; R _ifor the reception coefficient of antenna i, T _ifor the emission ratio of antenna i; R _kfor the reception coefficient of antenna k, T _kfor the emission ratio of antenna k.

11. base stations according to claim 9, is characterized in that, described self calibration unit comprises:

Test signal transceiver module, for when carrying out channel estimating to the antenna i of this base station to all links of user terminal, in this base station, Signal reception is carried out in the Received signal strength side of antenna k, obtains the first signal; Further, for when carrying out channel estimating to the antenna k of this base station to all links of user terminal, in this base station, Signal reception is carried out in the Received signal strength side of antenna i, obtains secondary signal;

Self-adjusting Coefficient generation module, for the first signal and secondary signal being compared, obtains the self-adjusting coefficient between antenna k and antenna i wherein i=1 ..., M; K=1 ..., M and i ≠ k; R _ifor the reception coefficient of antenna i, T _ifor the emission ratio of antenna i; R _kfor the reception coefficient of antenna k, T _kfor the emission ratio of antenna k.

12. base stations according to claim 10 or 11, it is characterized in that, described calibration factor determining unit is used for:

According to wherein antenna I of this base station of the described user terminal report received channel information to all links of described user terminal, and described channel estimating unit provide to the channel information of user terminal to all links of this base station, determine the calibration factor α relevant with antenna I _i,j, wherein j=1 ..., N;

And according to formula α _k,j=β _k,Iα _i,j, determine the calibration factor relevant with antenna k, wherein k=1 ..., M and k ≠ I.

13. 1 kinds for the user terminal of time division duplex mimo system, is characterized in that, comprising:

Channel estimating unit, for carrying out channel estimating to base station to all links of this user terminal;

Self calibration unit, for carrying out self calibration to the M root antenna of self, obtains self-adjusting coefficient;

Calibration factor determining unit, for the channel information of the wherein antenna I to all links of described base station that receive this user terminal of described base station repeats, and provide according to this channel information, described channel estimating unit determine calibration factor for described base station to the channel information of all links of this user terminal and described self-adjusting coefficient.