Smart antenna communication system for signal calibration

• US 20060135211A1
• Filed: 12/02/2005
• Published: 06/22/2006
• Est. Priority Date: 12/02/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kwon, Young-Hoon, Yang, Jang-Hoon, Chae, Heon-Ki
• Granted Patent: US 7,801,564 B2
• Time in Patent Office: Days
• US Class Current: 455/562.100
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence

Abstract

A calibration apparatus and method for controlling the phase and amplitude of a signal in a smart antenna multicarrier communication system are provided. A calibration signal is allocated to remaining carriers after allocating carriers to a data signal, prior to transmission. Thus, the efficiency of frequency resources for data transmission is increased.

Claims

1. A smart antenna communication system comprising:

a scheduler for allocating a data signal to a plurality of carriers as data carriers, providing the data signal to a baseband processor, and controlling a calibration processor and a controller to generate a calibration signal to be allocated to non-data carriers to which the data signal is not allocated;

the calibration processor and the controller for generating the calibration signal on the non-data carriers under the control of the scheduler, and calculating a calibration vector using the calibration signal and a feedback calibration signal, being the calibration signal passed through a transmission path; and

the baseband processor for calibrating a beamforming weight vector for a data signal with the calibration vector and transmitting the calibrated data signal in the transmission path.

2. The smart antenna communication system of claim 1, wherein the calibration processor and controller comprises:

a calibration signal generator for generating the calibration signal on the non-data carriers under the control of the scheduler; and

a calibration vector processor for calculating the calibration vector using the calibration signal and the feedback calibration signal.

3. The smart antenna communication system of claim 2, wherein the calibration signal generator comprises:

a calibration signal allocater for allocating the calibration signal to the non-data carriers according to carrier-data allocation information received from the scheduler; and

an IFFT processor for modulating the calibration signal received from the calibration signal allocater by IFFT.

4. The smart antenna communication system of claim 2, wherein the calibration vector processor comprises:

a fast Fourier transform (FFT) processor for separating the feedback calibration signal by carriers;

a calibration signal acquirer for measuring the phases and amplitudes of the calibration signal on the non-data carriers to which the calibration signal is allocated, based on calibration carrier position information received from the scheduler;

a calibration signal updater for updating a memory with the phase and amplitude measurements; and

a calibration vector calculator for eliminating coupler characteristics from the phase and amplitude measurements stored in the memory and calculating a calibration vector using the coupler characteristics from phase and amplitude measurements.

5. The smart antenna communication system of claim 4, further comprising an interpolator for estimating the phases and amplitudes of the calibration signal on carriers to which the calibration signal is not allocated by interpolating the phase and amplitude measurements stored in the memory, and storing the estimated phased and amplitudes of the calibration signal in the memory.

6. The smart antenna communication system of claim 1, wherein the scheduler comprises:

a carrier-set finder for finding carriers having timer values not exceeding a threshold as data carriers;

a data allocater for allocating the data signal to the data carriers; and

a timer for updating timer values for the data carriers.

7. The smart antenna communication system of claim 1, wherein the baseband processor comprises:

a data mapper for receiving the data signal allocated to the data carriers by the scheduler;

a calibrator for applying the calibration vector received from the calibration vector processor to the data signal; and

an inverse fast Fourier transform (IFFT) processor for modulating the data signal received from the calibrator by IFFT.

8. The smart antenna communication system of claim 1, wherein the smart antenna communication system is an Orthogonal Frequency Division Multiplexing (OFDM) or an Orthogonal Frequency Division Multiple Access (OFDMA) communication system.

9. A smart antenna communication system comprising:

a scheduler for controlling a calibration signal generator to generate a calibration signal to be allocated to non-data carriers other than data carriers on which a data signal is received from a mobile station;

a calibration processor and controller for generating the calibration signal on the non-data carriers under the control of the scheduler and calculating a calibration vector using the calibration signal and a feedback calibration signal being the calibration signal passed through a reception path; and

a baseband processor for calibrating a beamforming weight vector for a data signal with the calibration vector and transmitting the calibrated data signal in the reception path.

10. The smart antenna communication system of claim 9, wherein the calibration processor and controller comprises:

the calibration signal generator for generating the calibration signal on the non-data carriers under the control of the scheduler; and

a calibration vector processor for calculating the calibration vector using the calibration signal and the feedback calibration signal.

11. The smart antenna communication system of claim 10, wherein the smart antenna communication system is an OFDM (Orthogonal Frequency Division Multiplexing) or an OFDMA (Orthogonal Frequency Division Multiple Access) communication system.

12. A method of allocating a calibration signal to carriers in a smart antenna communication system, comprising the steps of:

comparing a timer value of the n^th carrier with a timer threshold (Time_threshold);

excluding the n^th carrier as unavailable as a data carrier if timer value of the n^th carrier is greater than the threshold;

allocating data on the n^th carrier if timer value of the n^th carrier is not greater than the timer threshold;

allocating a calibration signal on the n^th carrier if data is not allocated in the step of allocating data.

13. A method of estimating a calibration vector in a smart antenna communication system, comprising the steps of:

receiving a feedback calibration signal on a carrier to which a calibration signal is allocated;

updating a memory having the values of the feedback calibration signal received on previous carriers with the value of the feedback calibration signal;

repeating the reception step and the updating step for all carriers of a symbol; and

calculating a calibration vector for each of the carriers using the values of the feedback calibration signal stored in the memory.

14. The method of claim 13, wherein the calculation step comprises eliminating a coupler characteristic from the values of the feedback calibration signal stored in the memory and calculating the calibration vector for the each carrier.

15. The method of claim 13, wherein the calculation step comprises calculating the calibration vector for the each carrier by estimating the values of the feedback calibration signal on carriers to which the calibration signal is not allocated.

16. A signal calibration method in a smart antenna communication system, comprising the steps of:

allocating a data signal to a plurality of carriers as data carriers;

allocating a calibration signal to non-data carriers to which the data signal is not allocated and transmitting the calibration signal in a transmission path;

calculating a calibration vector using the calibration signal and a feedback calibration signal received from the transmission path; and

calibrating a beamforming weight vector for the data signal using the calibration vector and transmitting the calibrated data signal in the transmission path.

17. The signal calibration method of claim 16, wherein the calibration signal allocation and transmission step comprises:

allocating the calibration signal to the non-data carriers; and

modulating the allocated calibration signal.

18. The signal calibration method of claim 16, wherein the calibration and transmission step comprises:

receiving the data signal on each of the data carriers;

applying the calibration vector to the data signal; and

modulating the data signal to which the calibration vector is applied.

19. The signal calibration method of claim 16, wherein the calculation step comprises the steps of:

separating the feedback signal by carriers;

measuring the phases and amplitudes of the calibration signal on the non-data carriers to which the calibration signal is allocated based on calibration carrier position information;

updating a memory with the phase and amplitude measurements; and

eliminating coupler characteristics from the phase and amplitude measurements stored in the memory and calculating a calibration vector using the coupler characteristics-free from phase and amplitude measurements.

20. The signal calibration method of claim 19, wherein the memory updating step comprises estimating the phases and amplitudes of the calibration signal on carriers to which the calibration signal is not allocated by interpolating the phase and amplitude measurements stored in the memory, and storing the estimated phased and amplitudes of the calibration signal in the memory.