Systems methods circuits and apparatus for calibrating wireless communication systems

• US 8,837,563 B2
• Filed: 08/17/2012
• Issued: 09/16/2014
• Est. Priority Date: 08/17/2011
• Status: Active Grant

• Current Assignee: Gonet Systems Ltd.
• Original Assignee: Gonet Systems Ltd.
• Inventors: Salhov, Moshe, Kinamon, Roy
• Primary Examiner(s): Tran, Khanh C
• Application Number:
  US13/588,036
• Publication Number:
  US 20130208774A1
• Time in Patent Office: 760 Days
• Field of Search: 375219-220, 375/222, 375/285, 375295-296, 375/316, 455/501, 455/63.1, 455/67.11, 455/67.13, 4551151-1152
• US Class Current: 375/220
• CPC Class Codes: H04B 17/0085 using test signal generators
• 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 17/29 Performance testing
• CPC Class Codes: H04B 7/005 Control of transmission; Equalising
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end

Abstract

Disclosed are wireless communication systems and methods for calibrating same. The communication systems may include first wireless transceivers having: (a) a modem, and (b) one or more Radio Frequency (RF) chain pairs. There may also be included a sounding circuit block. A calibrated switchable bridging block (CSBB) may switchably couple signals between the first transceivers and the sounding circuit block. Calibration control logic may regulate signal flow through said CSBB during a sounding sequence of said first wireless transceiver and may apply compensation coefficients to RF compensation circuits functionally associated with said the wireless transceiver RF chain pairs.

Claims

1. A wireless communication system comprising:

one or more antenna elements;

a first wireless transceiver comprising;

(a) a modem, and (b) one or more Radio Frequency (RF) chain pairs, wherein at least one RF chain pair includes;

(i) a receive chain (RX), and (ii) a transmit chain (TX);

a sounding circuit block comprising;

(a) a receive chain (RX), (b) a transmit chain (TX); and

control circuitry adapted to coordinate;

(1) reception of sounding signals from said first wireless transceiver, and (2) transmission of sounding signals to said first wireless transceiver; and

a calibrated switchable bridging block (CSBB) switchably coupling signals between said first transceivers and said sounding circuit block, said CSBB comprising;

a controllable signal switch having known channel characteristics between ports of said switch.

2. The wireless communication system according to claim 1, further comprising calibration control logic adapted to regulate signal flow through said CSBB during a sounding sequence of said first wireless transceiver and to apply compensation coefficients to RF compensation circuits functionally associated with said first wireless transceiver RF chain pairs.

3. The wireless communication system according to claim 2, wherein said sounding circuit block includes a second wireless transceiver comprising a second transceiver modem.

4. The wireless transmission system according to claim 3, wherein said calibration control logic is adapted to initiate a TX chain sounding sequence during which:

(1) at least one of said first transceiver TX chains is communicatively coupled through said CSBB to the RX chain of said second wireless transceiver;

(2) said modem and communicatively coupled TX chains of said first transceiver generate a sounding signal;

(3) the coupled RX chain of said second transceiver receives the generated sounding signal; and

(4) a channel estimator of said second transceiver modem analyzes the received sounding signal to estimate a channel characteristic of at least a portion of signal paths, including the first transceiver TX chains, between said first transceiver modem and said second transceiver modem.

5. The wireless transmission system according to claim 4, wherein said calibration control logic is adapted to perform TX chain calibration by:

(1) calculating TX chain compensation coefficients at least partially based on channel characteristics estimated during the TX chain sounding sequence; and

(2) applying the TX chain compensation coefficients to compensation circuits functionally associated with said first transceiver TX chains.

6. The wireless transmission system according to claim 3, wherein said calibration control logic is adapted to initiate a RX chain sounding sequence during which:

(1) at least one of said first transceiver RX chains is communicatively coupled through said CSBB to the TX chain of said second wireless transceiver;

(2) said modem and communicatively coupled TX chain of said second transceiver generate a sounding signal;

(3) the coupled RX chains of said first transceiver receive the generated sounding signal; and

(4) a channel estimator of said first transceiver modem analyzes the received sounding signal to estimate a channel characteristic of at least a portion of signal paths, including the first transceiver RX chains, between said second transceiver modem and said first transceiver modem.

7. The wireless transmission system according to claim 6, wherein said calibration control logic is adapted to perform RX chain calibration by:

(1) calculating RX chain compensation coefficients at least partially based on channel characteristics estimated during the RX chain sounding sequence; and

(2) applying the RX chain compensation coefficients to compensation circuits functionally associated with said first transceiver RX chains.

8. The wireless transmission system according to claim 6, wherein the sounding signal generated by said modem and communicatively coupled TX chain of said second transceiver is a wireless packet with a known signal pattern.

9. The wireless transmission system according to claim 8, wherein the wireless packet includes a payload with estimated channel characteristic of at least a portion of signal paths, including the first transceiver TX chains, between said first transceiver modem and said second transceiver modem.

10. The wireless communication system according to claim 2, wherein said sounding circuit block comprises signal sampling and storage circuits and a signal synthesizer.

11. The wireless transmission system according to claim 10, wherein said calibration control logic is adapted to initiate a RX chain sounding sequence during which:

(1) at least one of said first transceiver RX chains is communicatively coupled through said CSBB to the TX chain of said sounding circuit block;

(2) a synthesizer and communicatively coupled TX chain of said signal sounding block generate a sounding signal including a known pattern;

(3) the coupled RX chains of said first transceiver receive the generated sounding signal; and

(4) a channel estimator of said first transceiver modem analyzes the received sounding signal to estimate a channel characteristic of at least a portion of signal paths, including the first transceiver RX chains, between the signal sounding block synthesizer and said first transceiver modem.

12. The wireless transmission system according to claim 11, wherein said calibration control logic is adapted to perform RX chain calibration by:

(1) calculating RX chain compensation coefficients at least partially based on channel characteristics estimated during the RX chain sounding sequence; and

(2) applying the RX chain compensation coefficients to compensation circuits functionally associated with said first transceiver RX chains.

13. The wireless transmission system according to claim 10, wherein said calibration control logic is adapted to initiate a TX chain sounding sequence during which:

(1) at least one of said first transceiver TX chains is communicatively coupled through said CSBB to the RX chain of said sounding circuit block;

(2) said modem and communicatively coupled TX chains of said first transceiver generate a sounding signal;

(3) the coupled RX chain of said sounding circuit block receives the generated sounding signal;

(4) the received sounding signal is sampled and stored by a signal sampling and storage block;

(5) upon the TX chain of said sounding circuit being bridged into RX chains of said first wireless transceiver, a signal synthesizer generates and transmits the stored sounding signal back to said first wireless transceiver; and

(6) a channel estimator of said first transceiver modem analyzes the received sounding signal to estimate a channel characteristic of at least a portion of signal paths, including the first transceiver TX chains, between said first transceiver modem and said second transceiver modem.

14. The wireless transmission system according to claim 13, wherein said calibration control logic is adapted to perform TX chain calibration by:

(1) calculating TX chain compensation coefficients at least partially based on channel characteristics estimated during the TX chain sounding sequence; and

(2) applying the TX chain compensation coefficients to compensation circuits functionally associated with said first transceiver TX chains.

15. The wireless transmission system according to claim 14, wherein calculating TX chain compensation coefficients at least partially based on channel characteristics estimated during the TX chain sounding sequence also includes factoring channel characteristics estimated during the RX chain sounding sequence.

16. A method for calibrating a wireless communication system comprising:

switchably coupling signals between a first wireless transceiver and a sounding circuit block through a calibrated signal switch having known channel characteristics between ports of the switch;

generating sounding signals at the first wireless transceiver and at the sounding circuit block;

transmitting the sounding signals in both directions between the sounding circuit block and the first transceiver; and

generating compensation coefficients based on channel estimations performed on received sounding signals.

17. The method according to claim 16, wherein a TX chain sounding sequence includes:

(1) at least one of the first transceiver TX chains being communicatively coupled through a calibrated switchable bridging block (CSBB) to the RX chain of a second wireless transceiver on the sounding circuit block;

(2) a modem and communicatively coupled TX chains of the first transceiver generating a sounding signal;

(3) the coupled RX chain of the second transceiver receiving the generated sounding signal; and

(4) a channel estimator of the second transceiver analyzing the received sounding signal to estimate a channel characteristic of at least a portion of signal paths, including the first transceiver TX chains, between said transceiver and said second transceiver.

18. The method according to claim 17, wherein TX chain calibration includes:

(1) calculating TX chain compensation coefficients at least partially based on channel characteristics estimated during the TX chain sounding sequence; and

(2) applying the TX chain compensation coefficients to compensation circuits functionally associated with said first transceiver TX chains.

19. The method according to claim 16, wherein RX chain sounding sequence includes:

(1) at least one of said first transceiver RX chains being communicatively coupled through a calibrated switchable bridging block (CSBB) to the TX chain of said second wireless transceiver;

(2) said modem and communicatively coupled TX chain of said second transceiver generating a sounding signal;

(3) the coupled RX chains of said first transceiver receiving the generated sounding signal; and

(4) a channel estimator of said first transceiver analyzing the received sounding signal to estimate a channel characteristic of at least a portion of signal paths, including the first transceiver RX chains, between said second transceiver modem and said first transceiver modem.

20. The method according to claim 19, wherein RX chain calibration includes:

(1) calculating RX chain compensation coefficients at least partially based on channel characteristics estimated during the RX chain sounding sequence; and

(2) applying the RX chain compensation coefficients to compensation circuits functionally associated with said first transceiver RX chains.

21. The method according to claim 16, wherein a RX chain sounding sequence includes:

(1) at least one of said first transceiver RX chains being communicatively coupled through a calibrated switchable bridging block (CSBB) to the TX chain of said sounding circuit block;

(2) a synthesizer and communicatively coupled TX chain of said signal sounding block generating a sounding signal including a known pattern;

(3) the coupled RX chains of said first transceiver receiving the generated sounding signal; and

(4) a channel estimator of said first transceiver analyzing the received sounding signal to estimate a channel characteristic of at least a portion of signal paths, including the first transceiver RX chains, between the signal sounding block synthesizer and said first transceiver modem.

22. The method according to claim 21, wherein RX chain calibration includes:

(1) calculating RX chain compensation coefficients at least partially based on channel characteristics estimated during the RX chain sounding sequence; and

(2) applying the RX chain compensation coefficients to compensation circuits functionally associated with said first transceiver RX chains.

23. The method according to claim 16, wherein a TX chain sounding sequence includes:

(1) at least one of said first transceiver TX chains being communicatively coupled through a calibrated switchable bridging block (CSBB) to the RX chain of said sounding circuit block;

(2) said modem and communicatively coupled TX chains of said first transceiver generating a sounding signal;

(3) the coupled RX chain of said sounding circuit block receiving the generated sounding signal;

(4) the received sounding signal being sampled and stored by a signal sampling and storage block;

(5) upon the TX chain of said sounding circuit being bridged into RX chains of said first wireless transceiver, a signal synthesizer generating and transmitting the stored sounding signal back to said first wireless transceiver; and

(6) a channel estimator of said first transceiver analyzing the received sounding signal to estimate a channel characteristic of at least a portion of signal paths, including the first transceiver TX chains, between said first transceiver modem and said second transceiver modem.

24. The method according to claim 23, wherein TX chain calibration includes:

(1) calculating TX chain compensation coefficients at least partially based on channel characteristics estimated during the TX chain sounding sequence; and

(2) applying the TX chain compensation coefficients to compensation circuits functionally associated with said first transceiver TX chains.

25. A method for calibrating a wireless communication system comprising:

receiving a first sounding signal generated by a first wireless transceiver at a second wireless transceiver, both of which are integrated within said wireless communication system;

receiving a second sounding signal generated by the second wireless transceiver at the first wireless transceiver, wherein a payload of the second sounding signal includes channel estimations derived from the first sounding signal, thereby proving the first transceiver with channel estimates performed by the second transceiver; and

generating compensation coefficients based on channel estimations performed on the second sounding signal and factoring channel estimations performed of the first sounding signal.