Periodic calibration on a communications channel

• US 20030050016A1
• Filed: 04/29/2002
• Published: 03/13/2003
• Est. Priority Date: 05/01/1998
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: ArrayComm LLC (Ygomi LLC)
• Inventors: Barratt, Craig H., Uhlik, Christopher R., Trott, Mitchell D., Boros, Tibor
• Granted Patent: US 6,963,742 B2
• Time in Patent Office: Days
• US Class Current: 455/67.14
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices
• CPC Class Codes: H04B 17/10 of transmitters
• CPC Class Codes: H04B 17/11 for calibration
• CPC Class Codes: H04B 17/12 of transmit antennas, e.g. of the amplitude or phase
• CPC Class Codes: H04B 17/14 of the whole transmission and reception path, e.g. self-test loop-back
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements
• CPC Class Codes: H04B 7/005 Control of transmission; Equalising
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0842 Weighted combining
• CPC Class Codes: H04B 7/0848 Joint weighting
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end

Abstract

A method and apparatus for estimating the downlink signature for a remote transceiver which is part of a wireless communication system that includes a main transceiver for communicating with the remote transceiver. The main transceiver includes an array of transmit antenna elements. The method uses the remote transceiver for receiving signals when the main transceiver transmits downlink calibration signals. When the main transceiver also has a receive antenna array, the remote transceiver can transmit uplink calibration signals to the main transceiver for determining an uplink signature. The downlink and uplink signatures are used to determine a calibration function to account for differences in the apparatus chains that include the antenna elements of the arrays, and that enable downlink smart antenna processing weights to be determined from uplink smart antenna processing weights when the main transceiver includes means for smart antenna processing according to weights.

Claims

1. In a wireless communication system comprising a main transceiver and a remote transceiver capable of receiving signals from and transmitting signals to the main transceiver, the main transceiver comprising an array of transmit antenna elements, and at least one receive antenna element, each transmit antenna element being part of a transmit electronics chain for transmitting a transmit apparatus signal using the transmit antenna element, and each receive antenna element being part of a receiver apparatus chain for receiving a received antenna signal from the receive antenna element, the main transceiver and the remote transceiver designed for mutual communication using waveforms conforming to an air interface standard, a method for estimating the downlink signature for the remote transceiver, the method comprising:

(a) transmitting a set of one or more downlink calibration waveforms from the main transceiver via the transmit antenna array to the remote transceiver, the set of downlink calibration waveforms substantially conforming to the air interface standard;

(b) processing the signals received at the remote transceiver corresponding to the downlink calibration waveforms, the processing to determine downlink signature related signals related to the downlink signature for the remote transceiver;

(c) transmitting the downlink signature related signals from the remote transceiver to the main transceiver using waveforms substantially conforming to the air interface standard; and

(d) determining the downlink signature of the remote transceiver from the downlink signature related signals received at the main transceiver.

2. The method of claim 1, wherein the at least one receive antenna element are a plurality of receive antenna elements forming an array of receive antenna elements, the number of elements in the array of receive antenna elements being the same as the number of antenna elements in the array of transmit antenna elements, the method further comprising:

(e) transmitting a set of one or more uplink calibration waveforms from the remote transceiver to the main transceiver, the set of downlink calibration waveforms substantially conforming to the air interface standard;

(f) processing at the main transceiver the received antenna signals corresponding to the uplink calibration signals transmitted from the remote transceiver, the processing determining the uplink signature for the remote transceiver; and

(h) determining a calibration function for the main transceiver from the uplink and downlink signatures for the remote transceiver.

3. In a wireless communication system comprising a main transceiver and a remote transceiver capable of receiving signals from and transmitting signals to the main transceiver, the main transceiver comprising an array of transmit antenna elements, and at least one receive antenna element, each transmit antenna element being part of a transmit electronics chain for transmitting a transmit apparatus signal using the transmit antenna element, and each receive antenna element being part of a receiver apparatus chain for receiving a received antenna signal from the receive antenna element, the main transceiver and the remote transceiver designed for mutual communication using waveforms conforming to an air interface standard, a method for estimating the downlink signature for the remote transceiver, the method comprising:

(a) transmitting a set of one or more downlink calibration waveforms from the main transceiver via the transmit antenna array to the remote transceiver, the set of downlink calibration waveforms designed to be robust to one or more of the set comprising frequency offset, phase noise, I/Q mismatch, and timing offset;

(b) processing the signals received at the remote transceiver corresponding to the downlink calibration waveforms, the processing to determine downlink signature related signals related to the downlink signature for the remote transceiver;

(c) transmitting the downlink signature related signals from the remote transceiver to the main transceiver; and

(d) determining the downlink signature of the remote transceiver from the downlink signature related signals received at the main transceiver.

4. The method of claim 3, wherein the at least one receive antenna element are a plurality of receive antenna elements forming an array of receive antenna elements, the number of elements in the array of receive antenna elements being the same as the number of antenna elements in the array of transmit antenna elements, the method further comprising:

(e) transmitting a set of one or more uplink calibration waveforms from the remote transceiver to the main transceiver, the set of downlink calibration waveforms;

(f) processing at the main transceiver the received antenna signals corresponding to the uplink calibration signals transmitted from the remote transceiver, the processing determining the uplink signature for the remote transceiver; and

(g) determining a calibration function for the main transceiver from the uplink and downlink signatures for the remote transceiver.

5. The method of claim 3, wherein each of the set of downlink calibration waveforms conforms to the air interface standard.

6. In a wireless communication system comprising a main transceiver and a remote transceiver capable of receiving signals from and transmitting signals to the main transceiver, the main transceiver comprising an array of transmit antenna elements, and at least one receive antenna element, each transmit antenna element being part of a transmit electronics chain for transmitting a transmit apparatus signal using the transmit antenna element, and each receive element being part of a receiver apparatus chain for receiving a received antenna signal from the receive antenna element, the main communication transceiver designed to transmit traffic waveforms, the main communication transceiver also designed to transmit downlink calibration waveforms, a method for estimating the downlink signature for the remote transceiver, the method comprising:

(a) transmitting downlink calibration waveforms and traffic waveforms from the main transceiver via the transmit antenna array to the remote transceiver, the downlink calibration waveforms interspersed with the traffic waveforms;

(b) determining at the remote transceiver whether the signals received at the remote transceiver correspond to downlink calibration waveforms or to traffic waveforms;

(c) processing signals received at the remote transceiver determined in step (b) to correspond to downlink calibration waveforms, the processing to determine downlink signature related signals related to the downlink signature for the remote transceiver;

(d) processing signals received at the remote transceiver determined in step (b) to correspond to traffic waveforms, the processing to perform normal traffic functions;

(e) transmitting the downlink signature related signals from the remote transceiver to the main transceiver; and

(f) determining the downlink signature of the remote transceiver from the downlink signature related signals received at the main transceiver.

7. The method of claim 6, wherein the downlink calibration waveforms are transmitted during silent periods.

8. The method of claim 6, wherein the downlink calibration waveforms are transmitted only after a number of idle waveforms are transmitted from the main transceiver.