KR20050050829A - Beam forming method for antenna, and apparatus for the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a beam of an antenna and a device for forming the beam, in particular in a code division multiple access (CDMA) communication system. Provided are a beamforming method of an antenna and an apparatus therefor for simplifying a calculation of a downlink beamforming weight vector using only one information.

Description

Beamforming method of antenna and apparatus for same

The present invention relates to a communication system, and more particularly, to a method for forming a beam of an antenna and a device for forming the beam in a code division multiple access (CDMA) communication system.

In general, a beamforming method of downlink for a smart antenna is classified as follows.

Probing-Feedback approach: A method of estimating an instantaneous downlink channel response.

Direct of Arrival based approach (DOA-based approach): A method of estimating and using direction information. Where DOA is Direct of Arrival.

Frequency-Calibrated (FC) approach: A method of estimating statistical downlink channel response.

Other methods used (Centralized algorithm): A method of minimizing the overall transmitted power while maintaining the signal-to-interference ratio (SIR) requirements.

In the related art using the above-listed schemes, downlink beamforming weights may be determined from downlink channel information.

However, in the frequency division duplex mode (FDD mode), the downlink channel covariance matrix required for a base station to estimate downlink beamforming weights for downlink beamforming. covariance matrix (DCCM) Here "covariance" means a statistical measure of the change of a plurality of variables.

There is also a method of estimating downlink channel information from the obtained uplink channel information. That is, the relation of downlink channel information with respect to uplink channel information can be obtained through specific frequency calibration processing that can be applied by using a complex frequency measurement matrix (FC). The downlink channel information can be obtained through the above-described equation.

On the other hand, it is not easy to estimate information on the direction of the multipath of a desired signal in a multipath environment. Thus, in the prior art, there is a practical limit to applying a direct of an rival based approach (DOA-based approach) for downlink beamforming.

In addition, in the related art, a mobile terminal estimates downlink channel information, feeds back to a base station, and informs the base station, and the base station enables downlink beamforming through the base station. However, there are errors and delays caused by feedback, and there is a disadvantage that a change of uplink and downlink protocols is required.

SUMMARY OF THE INVENTION An object of the present invention has been made in view of the above points, and in a multipath environment, a beamforming method of an antenna suitable for allowing a receiver to more easily calculate a downlink beamforming weight vector using only information that it has or has calculated. And a device therefor.

It is yet another object of the present invention to provide a beamforming method of an antenna and an apparatus therefor suitable for preventing a separate operation or processing for downlink beamforming in a multipath environment.

A first aspect of the beamforming method according to the present invention for achieving the above object is the step of calculating the weight vectors (PPPW: Per-path-per-weight) for each path in the uplink multipath (PPPW), And assigning the calculated weight vectors (PPPW) for each path to the corresponding paths of the uplink and downlink to form beam patterns for each path.

More preferably, when different carrier frequencies are used in each of the uplink and the downlink, that is, in the case of a frequency division duplex mode (FDD mode), the calculated angle Compensating the path-specific weight vectors (PPPWs) by the carrier frequency difference between the uplink and the downlink, respectively, and assign them to the corresponding paths of the downlink, while the same carrier frequency is used in each path of the uplink and the downlink. In other words, in the case of a time division duplex mode (TDD mode), the calculated weight vector PPPW for each path is allocated to the corresponding path of the uplink and the downlink with the same value.

More preferably, the method further includes generalizing the equalized gain combining PPPWs for each path, and assigning the generalized weight vector to the downlink paths. It is characteristic.

A second feature of the beamforming method according to the present invention for achieving the above object is that the receiver having a figure for each path beams for the uplink figures through a preset weight vector generation algorithm. Calculating each formation weight vector (uplink PPPW) and converting the calculated beamforming weight vectors (uplink PPPW) into at least one beamforming weight vector (downlink PPPW) for downlink figures. And forming a beam pattern of corresponding downlink figures by using the transformed beamforming weight vector (downlink PPPW).

More preferably, the beamforming weight vectors (uplink PPPWs) for the calculated uplink figures are equal-gain combined to convert into one normalized beamforming weight vector, wherein The transformed generalized beamforming weight vector is equally used for the downlink figures.

More preferably, the calculated beamforming weight vectors (uplink PPPW) for the uplink figures are used as the beamforming weight vectors (downlink PPPW) for the downlink figures without any modification.

More preferably, the calculated beamforming weight vectors (uplink PPPW) for the uplink figures are compensated by the carrier frequency difference between the uplink and the downlink to form the beamforming for the downlink figures. Convert to weight vectors (downlink PPPW). Optionally, beamlink weighting vectors (downlink PPPWs) for downlink figures transformed through the compensation are equal-gain combined and converted into one normalized beamforming weight vector.

A feature of the beamforming apparatus according to the present invention for achieving the above object is to obtain the beamforming weight vector (uplink PPPW) for each path in the uplink paths, respectively, the beamforming weight vector for each path ( a weight vector generator for converting uplink PPPWs into at least one weight vector for downlink beamforming, and a beam for the downlink paths using the converted weight vector; It is configured to include a beamforming module (beamforming module) for forming a pattern.

More preferably, the weight vector generation unit is obtained when different carrier frequencies are used in each of the uplink and the downlink, that is, in the case of a frequency division duplex mode (FDD mode). Compensating the uplink PPPW for each path of the uplink by the carrier frequency difference between the uplink and the downlink is converted into the downlink beamforming weight vector (downlink PPPW), while the uplink and the uplink When the same carrier frequency is used in each downlink path, that is, in a time division duplex mode (TDD mode), the obtained beamforming weight vector (uplink PPPW) for each path of the uplink is determined. A beamforming weight vector (downlink PPPW) for each path of the downlink is used without any change.

More preferably, the weight vector generation unit generalizes the transformed downlink weight vector for each downlink by equal-gain combining, and generalizes the generalized weight vector to each of the downlinks. Use the same for paths.

The beamforming method and apparatus for the antenna according to the present invention having the above-mentioned features are provided in the code division multiple access (CDMA) in a multipath environment using smart antenna technology. It is used for system or next generation communication system (eg IMT2000 system) which will be commercialized in the future.

Other objects, features and advantages of the invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

Hereinafter, a beam forming method of an antenna and an apparatus therefor according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing an apparatus configuration for beam forming according to the present invention.

1 illustrates an internal configuration of a receiver for beamforming, particularly in a base station system having a smart antenna.

Referring to FIG. 1, an interior of a receiver for downlink beamforming includes a beamforming module 10 and a weight vector generator 20. And a receiver that provides multipath is divided into a number of figures along each path.

The weight vector generator 20 generates a weight or a weight vector to be used for each figure and provides it to the beamforming module 10. The beamforming module 10 then forms a beam pattern using the updated weight or weight vector of each figure.

The present invention obtains a downlink beamforming weight or weight vector for a specific mobile terminal from uplink beamforming weight information obtained for each figure to improve uplink performance in a multipath environment based on the above configuration. The operation of each component associated with it will be described below.

The weight vector generator 20 calculates a beamforming weight vector (Per-path-per-weight; hereinafter abbreviated as PPPW) for each path or each figure in uplink paths or figures. . The calculated uplink PPPW for each path or each figure of the uplink of the uplink is converted into at least one weight vector (downlink PPPW) for downlink beamforming. At this time, the procedure or method of the conversion is described in more detail below with reference to FIG.

The beamforming module 10 receives the converted weight vector from the weight vector generator 20 to form a beam pattern for downlink paths or figures.

In particular, when different carrier frequencies are used in the uplink and the downlink such as the frequency division duplex mode (FDD mode), the weight vector generator 20 performs the downlink beamforming weight vector (downlink PPPW). When converting to the compensation for the beamforming weight vector (uplink PPPW) for each path or each figure of the uplink calculated in advance as much as the carrier frequency difference between the uplink and downlink. The downlink PPPWs are then used for beamforming in each corresponding path or figure.

However, in the case where the same carrier frequency is used in the uplink and the downlink as in the time division duplex mode (TDD mode), the weight vector generator 20 calculates each path or each of the uplinks calculated in advance. The figure-specific beamforming weight vector (uplink PPPW) may be used as the beamforming weight vector (downlink PPPW) for each path or each figure of the downlink without any change. That is, the uplink beamforming weight calculated for a specific uplink path or figure is used as the beamforming weight of the downlink path or figure mapped with the uplink path or figure.

In addition, as another example of the present invention, the weight vector generator 20 downlinks one weight vector without using different weights for each path or each figure of the downlink corresponding one-to-one to the path or the figure of the uplink. Use the same for each path or each figure in the link. In more detail, the weight vector generator 20 generalizes the weight vector downlink PPPW for each downlink or each figure by equal-gain combining. The generalized one weight vector is used equally for each path or each figure of the downlink. This separate example is optional, and applies only when one multipath environment is excellent in uplink and downlink, for example. More specifically, the receiver measures the service quality of the uplink and the downlink and uses the generalized weight vector equally in each of the downlinks or paths when the measured quality of service is above a certain level.

The following describes the beam shape procedure of the antenna.

2 illustrates a downlink beamforming procedure according to the present invention.

Referring to FIG. 2, a receiver having a figure for each path includes a weight vector generator for calculating a weight vector for improving uplink performance through a weight vector generation algorithm.

The weight vector generator of the receiver calculates a beamforming weight vector (uplink PPPW) for each uplink path or each figure through a preset weight vector generation algorithm (S10).

Subsequently, the weight vector generator converts the calculated uplink beamforming weight vectors (uplink PPPWs) into beamforming weight vectors (downlink PPPWs) for downlink paths or figures in a one-to-one mapping format (S11). . This conversion process is a case in which carrier frequencies used in uplink and downlink are different from each other, such as a frequency division duplex mode (FDD mode). Accordingly, the weight vector generator compensates the beamforming weight vectors (uplink PPPWs) for the respective uplink paths or the figures by the carrier frequency of the uplink and the downlink to compensate for the downlink paths. Or convert to beamforming weight vectors (downlink PPPWs) for figures.

However, when the same carrier frequency is used in the uplink and the downlink, such as a time division duplex mode (TDD mode), the weight vector generator generates a beam for a predetermined uplink path or each figure. The formation weight vectors (uplink PPPWs) are mapped one-to-one to beamforming weight vectors (downlink PPPWs) for downlink figures and used without change. This is a method used by the receiver when the multipath environment is above a certain level. As an example, the receiver measures service quality of uplink and downlink. Calculate the beamforming weight vectors (uplink PPPW) for each figure or each figure and use them as the beamforming weight vector (downlink PPPW) for the downlink paths or figures. In short, unlike the frequency division multiple mode (FDD mode) does not go through the above-described conversion process.

The final downlink beamforming weight vector (downlink PPPW) is calculated using the values determined as beamforming weight vectors (downlink PPPWs) for the downlink paths or figures (S12).

The process of calculating the final value is divided as follows.

First, one normalized beamforming weight vector is calculated by equal-gain combining the beamforming weight vectors (uplink PPPWs) for the pre-calculated uplink paths or figures. The generalized beamforming weight vector calculated at this time is used equally for the downlink path figures. This is preferably used in the case of time division duplex mode (TDD mode), but is not limited thereto.

Second, one normalized by equal-gain combining beamforming weight vectors (downlink PPPWs) for downlink paths or figures transformed through compensation of carrier frequency differences. Calculate the beamforming weight vector. The generalized beamforming weight vector calculated at this time is used equally for the downlink path figures. This is preferably used in the case of a frequency division duplex mode (FDD mode), but the present invention is not limited thereto.

Whether to implement the generalization process through equal-gain combining takes into account the multipath environment. That is, it is determined whether to perform the generalization process in consideration of uplink and downlink quality of service.

Finally, the weight vector generator provides the update value of the final weight to the beamforming module, and the beamforming module uses the downlink beamforming weight vector (PUPW: Per-user-per-weight) of the given mobile terminal to obtain the update value. A beam pattern of corresponding downlink paths or figures of the mobile terminal is formed (S13).

2, the present invention calculates weighted vectors (PPPW) for each path or each figure in an uplink multipath, and calculates the weighted vector for each path or each figure ( PPPWs) are assigned to corresponding paths or corresponding figures of uplink and downlink.

However, when the uplink weight vectors (uplink PPPWs) are allocated to the downlink weight vectors (downlink PPPW), the carriers are compensated by the difference between the uplink and downlink carrier frequencies and allocated to the corresponding paths of the downlink. Of course, when the same carrier frequency is used for the uplink and the downlink, the compensation of the carrier frequency difference is omitted.

In addition, one weight vector generalized through equal-gain combining is equally allocated to downlink paths.

According to the present invention described above, since the downlink beamforming weight vector can be simply calculated using the uplink beamforming weight vector obtained in the multipath environment, the downlink performance of a communication system using an antenna, in particular a smart antenna (downlink) capacity can be improved.

In addition, if the present invention, which obtains the downlink beamforming weight vector of the smart antenna modem in the multipath environment, is applied to the receiver of the next generation mobile communication system (eg IMT2000 system) to be commercialized, it will contribute to the downlink performance and capacity increase of the communication system. Can be.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

1 is a view showing a device configuration for forming a beam according to the present invention.

2 illustrates a downlink beamforming procedure according to the present invention.

* Explanation of symbols on the main parts of the drawings

10: beamforming module 20: weight vector generator

Claims (14)

Calculating weight vectors for each path in the uplink multipath; And forming a beam pattern for each path by assigning the calculated weight vectors for each path to the corresponding paths of the uplink and the downlink. The method of claim 1, wherein when different carrier frequencies are used in each of the paths of the uplink and the downlink, the calculated weight vectors for each path are compensated by the carrier frequency difference between the uplink and the downlink. The beamforming method of the antenna, characterized in that assigned to the corresponding path of the downlink. The method of claim 1, wherein when the same carrier frequency is used in each path of the uplink and the downlink, the calculated weight vectors for each path are assigned the same value to the corresponding path of the uplink and the downlink. Beam forming method of an antenna, characterized in that. 2. The method of claim 1, further comprising: generalizing by equal-gain combining the calculated weight vectors for each path; And assigning the generalized one weight vector to the downlink paths. Calculating a beamforming weight vector for uplink figures by a receiver having a figure for each path through a preset weight vector generation algorithm; Converting the calculated beamforming weight vectors into at least one beamforming weight vector for downlink figures; And forming a beam pattern of corresponding downlink figures by using the transformed beamforming weight vector. The antenna of claim 5, wherein the beamforming weight vectors of the calculated uplink figures are equal-gain combined and converted into one normalized beamforming weight vector. Beamforming method. 7. The method of claim 6, wherein the transformed generalized beamforming weight vector is equally used for the downlink figures. 6. The method of claim 5, wherein the calculated beamforming weight vectors for the uplink figures are used as beamforming weight vectors for the downlink figures. The method according to claim 5, wherein the beamforming weight vectors for the uplink figures are compensated by the difference between the carrier frequency of the uplink and the downlink to the beamforming weight vectors for the uplink figures. The beamforming method of the antenna, characterized in that for converting. 10. The method of claim 9, wherein the beamforming weight vectors for downlink figures transformed through the compensation are converted into one normalized beamforming weight vector by equal-gain combining. Beamforming method of the antenna. A weight vector generator for obtaining beamforming weight vectors for each path in uplink paths and converting the beamforming weight vectors for each path into at least one weight vector for downlink beamforming. )Wow; And a beamforming module for forming a beam pattern for the downlink paths using the converted weight vector. 12. The method of claim 11, wherein the weight vector generation unit, when different carrier frequencies are used in each of the paths of the uplink and the downlink, the uplink and the uplink And converting the downlink beamforming weight vector by compensating for the carrier frequency difference between downlinks. 12. The method of claim 11, wherein the weight vector generation unit, when the same carrier frequency is used in each of the path of the uplink and the downlink, the weighting beamforming weight vector for each path of the uplink obtained A beamforming method of an antenna, characterized in that used as a beamforming weight vector for each path. 12. The apparatus of claim 11, wherein the weight vector generation unit generalizes the transformed weight vector for each downlink path by equal-gain combining, and generalizes the generalized weight vector to each path of the downlink. Beam forming method of an antenna, characterized in that used in the same way.