Apparatus and method for a system architecture for multiple antenna wireless communication systems using round robin channel estimation and transmit beam forming algorithms

• US 20070093274A1
• Filed: 10/23/2006
• Published: 04/26/2007
• Est. Priority Date: 10/24/2005
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Liu, Li, Jafarkhani, Hamid
• Granted Patent: US 7,539,458 B2
• Time in Patent Office: Days
• US Class Current: 455/562.1
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]

Abstract

A multiple antenna wireless system including a transmitter and a receiver comprises a reconfigurable large antenna array having a plurality of antennas. A plurality of RF chains in the transmitter is coupled to the reconfigurable large antenna array. A pilot assisted round robin channel estimation means tracks the fading channel; and an adaptive round robin transmit beamforming means beam forms the reconfigurable large antenna array. A method for multiple antenna wireless communication comprising the steps of tracking a plurality of fading channels in a reconfigurable large antenna array having a plurality of antennas using pilot assisted round robin channel estimation to selectively couple a plurality of RF chains in the transmitter to the reconfigurable large antenna array, and adaptively, round-robin transmit beamforming the reconfigurable large antenna array.

Claims

1. A multiple antenna wireless system including a transmitter and a receiver comprising:

a reconfigurable large antenna array having a plurality of antennas;

a plurality of RF chains in the transmitter coupled to the reconfigurable large antenna array;

a pilot assisted channel estimation means for tracking of a fading channel; and

an adaptive transmit beamforming means at the transmitter for beamforming the reconfigurable large antenna array.

2. The system of claim 1 where the channel estimation means performs tracking of a fading channel and transmit beamforming means performs beam forming the reconfigurable large antenna array in a round-robin manner.

3. The system of claim 1 where the pilot assisted round robin channel estimation means and the adaptive transmit beamforming means operate at an optimal training duration for a given mobile speed of the receiver.

4. The system of claim 1 where the plurality of RF chains are divided into two groups, a first group of the RF chains being employed to drive a first group of antennas in the large antenna array for normal data transmissions, and a second group of the RF chains is comprised of an RF chain being employed to transmit a pilot training sequence on corresponding other one of the plurality of antennas.

5. The system of claim 4 where the second group of the RF chains is comprised of single RF chain.

6. The system of claim 4 where the second group of the RF chains transmit a pilot training sequence on corresponding other one of the plurality of antennas in a round robin fashion.

7. The system of claim 1 where the receiver measures performance of the fading channel, generates relative channel phase information, and feeds back the relative channel phase information to the transmitter, the system further comprises a plurality of RF phase shifters coupled to the large antenna array, the RF phase shifters being adjusted to perform co-phase transmission (CPT) using the relative channel phase information fed back from the receiver.

8. The system of claim 7 further comprising a plurality of RF switches for selectively coupling either a data signal to be transmitted or a piloting training signal to be transmitted to each of the antennas in the large antenna array.

9. The system of claim 8 further comprising a plurality of impedance matching circuits selectively coupled to each of the antennas in the large antenna array to provide impedance matching as different RF chains are selectively coupled to the antennas.

10. The system of claim 8 where the system is operated in an open loop mode where there is no channel state information available at the transmitter, where the receiver generates STCs to provide spatial diversity to compensate for channel fading, where the RF switches are configured into a predetermined corresponding position for each RF chain and where all of the phase shifters are configured into a fixed position so that all antennas coupled to RF chains driven in parallel operate as a single combined antenna with respect to channel path gain.

11. The system of claim 8 where the system is operated in a closed loop mode, where there is channel state information available at the transmitter from the receiver, where the phase shifters coupled to each RF chain are adaptively configured in a round robin fashion in that the RF switches are reconfigured such that a pilot training sequence is directed to a selected one of the antennas in the large antenna array in sequence until the corresponding channels for each of the antennas has been trained, the receiver calculating two effective channel path gains for each antenna without interrupting ongoing data communication, and feeding back channel phase information to the transmitter to reconfigure the phase shifter corresponding to the antenna being trained.

12. The system of claim 11 further comprising a baseband modulator coupled in sequence to each of the antennas of the large antenna array to provide a pilot training signal in sequence to each antenna as controlled by a selected configuration of the plurality of RF switches with the other ones of the antennas being coupled to a data signal, the receiver generating relative channel phase information between the antenna being trained and a first antenna trained, the receiver sending the relative channel phase information back to the transmitter for each antenna as it is trained, the phase shifter corresponding to the trained antenna being adjusted to attain maximum signal-to-noise ration (SNR) at the trained antenna.

13. The system of claim 1 where the pilot assisted round robin channel estimation means comprises means for separately estimating the channel path gain from each antenna of the large antenna array.

14. The system of claim 1 where the round robin channel estimation means and transmit beam forming means adaptively adjusts each antenna in the large antenna array such that the transmitted signal better or optimally fits the channel reality.

15. A method for multiple antenna wireless communication comprising:

tracking a plurality of fading channels in a reconfigurable large antenna array having a plurality of antennas using pilot assisted round robin channel estimation to selectively couple a plurality of RF chains in the transmitter to the reconfigurable large antenna array; and

adaptively, round-robin transmit beamforming the reconfigurable large antenna array.

16. The method of claim 15 where tracking of the fading channels and transmit beamforming are performed in a round-robin manner.

17. The method of claim 15 where tracking of the fading channels and transmit beamforming are performed at an optimal training duration for a given mobile speed of the receiver.

18. The method of claim 15 where tracking of the fading channels comprises driving a selected group of antennas in the large antenna array for normal data transmissions with a selected group of the RF chains, and transmitting a pilot training sequence on a different antenna and RF chain not included within the selected groups of antennas and RF chains.

19. The method of claim 15 where adaptively, round-robin transmit beamforming comprises measuring performance of the fading channel, generating relative channel phase information, and feeding back the relative channel phase information, adjusting a plurality of RF phase shifters coupled to the large antenna array to perform co-phase transmission (CPT) using the relative channel phase information fed back.

20. The method of claim 15 further comprising providing impedance matching as different RF chains are selectively coupled to the antennas.

21. The method of claim 15 where adaptively, round-robin transmit beamforming the reconfigurable large antenna array comprises transmit beamforming in an open loop mode where there is no channel state information available using STCs to provide spatial diversity to compensate for channel fading, where all but one of the antennas are coupled to a corresponding RF chain and operate as a single combined antenna with respect to channel path gain, the one antenna operating to track the plurality of fading channels.

22. The method of claim 15 where the system is operated in a closed loop mode, where there is channel state information available, where adaptively, round-robin transmit beamforming comprises directing a pilot training signal to a selected one of the antennas in the large antenna array in sequence until the corresponding channels for each of the antennas has been trained in a round robin fashion, and feeding back channel phase information to reconfigure the corresponding antenna being trained in a round robin fashion.

23. The method of claim 15 where the system is operated in a closed loop mode, and where adaptively, round-robin transmit beamforming comprises coupling a baseband modulator coupled in sequence to each of the antennas of the large antenna array to provide the pilot training signal in sequence to each antenna as controlled by a selected configuration of a plurality of RF switches with the other ones of the antennas being coupled to a data signal, generating relative channel phase information between the antenna being trained and a first antenna trained, sending the relative channel phase information back for each antenna as it is trained, adjusting a phase shifter corresponding to the trained antenna to attain maximum signal-to-noise ration (SNR) at the trained antenna.

24. The method of claim 15 where tracking a plurality of fading channels comprises separately estimating the channel path gain from each antenna of the large antenna array.

25. The method of claim 15 where adaptively, round-robin transmit beamforming the reconfigurable large antenna array comprises adaptively adjusting each antenna in the large antenna array such that the transmitted signal better or optimally fits the channel reality.