Method for acquiring channel state information in FDD MIMO wireless networks

• US 9,692,577 B2
• Filed: 12/20/2014
• Issued: 06/27/2017
• Est. Priority Date: 12/20/2013
• Status: Active Grant

• Current Assignee: RF DSP, Inc.
• Original Assignee: RF DSP, Inc.
• Inventors: Liang, Ping, Zhu, Dengkui
• Primary Examiner(s): Pezzlo, John
• Application Number:
  US15/101,949
• Publication Number:
  US 20160315749A1
• Time in Patent Office: 920 Days
• Field of Search: 370252, 370329, 370330, 370344, 370430
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

This invention presents methods and circuits for a BS to acquire DL CSI in a FDD wireless network comprising switching the normal transmitting and receiving frequencies in a first and a second FDD apparatus, and using UL pilot signals to estimate the DL CSI based on reciprocity of the over the air channels.

Claims

1. A method for a BS to acquire DL CSI in a FDD wireless network comprising a second FDD apparatus who normally receives UL signals in frequency band F2 from and sends DL signals in frequency band F1 to a first FDD apparatus whose DL CSI is to be estimated;

a CSI estimation enable control signal and a set of switches controlled by the CSI estimation enable control signal in the first FDD apparatus; and

upon the CSI estimation enable control signal becoming active, changing the connections of the set of switches so that the transmitting frequency band of a transmitter in the first FDD apparatus is changed from the normal transmitting frequency band F2 to the normal receiving frequency band F1 and the transmitting signal is transmitted out of a normal receiving antenna instead of a normal transmitting antenna; and

correspondingly, a second CSI estimation enable control signal and a second set of switches controlled by the CSI estimation enable control signal in the second FDD apparatus; and

upon the CSI estimation enable control signal becoming active, changing the connections of the set of switches so that the receiving frequency band of a receiver in the second FDD apparatus is changed from the normal receiving frequency band F2 to the normal transmitting frequency band F1 and the receiving signal is received from a normal transmitting antenna instead of a normal receiving antenna.

2. The method in claim 1 further comprising transmitting one or more pilot signals using the newly configured transmit path in the first FDD apparatus in the frequency band F1.

3. The method in claim 2 further comprising receiving the one or more pilot signals using the newly configured receiving path in the second FDD apparatus in the frequency band F1.

4. The method in claim 3 further comprising using the received one or more pilot signals in the frequency band F1 to estimate the UL channel from the first FDD apparatus to the second FDD apparatus in the frequency band F1.

5. The method in claim 4 further comprising using the estimation of the UL channel and calibration data of the hardware dependent components of the DL and UL channels to obtain an estimate of the DL channel from the second FDD apparatus to the first FDD apparatus in the frequency band F1 based on reciprocity of the over the air channel.

6. The method in claim 1 further comprising the normal receiving antenna and normal transmitting antenna in the first FDD apparatus are the same antenna.

7. The method in claim 1 further comprising the normal receiving antenna and normal transmitting antenna in the second FDD apparatus are the same antenna.

8. A circuit in a first FDD apparatus for estimating DL CSI in a FDD wireless network comprising generator of a CSI estimation enable control signal and a set of switches controlled by the CSI estimation enable control signal in the first FDD apparatus;

and upon the CSI estimation enable control signal becoming active, changing the connections of the set of switches so that the transmitting frequency band of a transmitter in the first FDD apparatus is changed from the normal transmitting frequency band F2 to the normal receiving frequency band F1 and the transmitting signal is transmitted out of a normal receiving antenna instead of a normal transmitting antenna.

9. The circuit in claim 8 further comprising transmitting to one or more second FDD apparatus one or more pilot signals using the newly configured transmit path in the first FDD apparatus in the frequency band F1.

10. The circuit in claim 8 further comprising the normal receiving antenna and normal transmitting antenna in the first FDD apparatus are the same antenna.

11. A circuit in a second FDD apparatus for estimating DL CSI in a FDD wireless network comprising generator of a CSI estimation enable control signal and a set of switches controlled by the CSI estimation enable control signal in the second FDD apparatus;

and upon the CSI estimation enable control signal becoming active, changing the connections of the set of switches so that the receiving frequency band of a receiver in the second FDD apparatus is changed from the normal receiving frequency band F2 to the normal transmitting frequency band F1 and the receiving signal is received from a normal transmitting antenna instead of a normal receiving antenna.

12. The circuit in claim 11 further comprising the normal receiving antenna and normal transmitting antenna in the second FDD apparatus are the same antenna.

13. The circuit in claim 11 further comprising receiving one or more pilot signals sent by a first FDD apparatus using the newly configured receiving path in the second FDD apparatus in the frequency band F1.

14. The circuit in claim 13 further comprising using the received one or more pilot signals in the frequency band F1 to estimate the UL channel from the first FDD apparatus to the second FDD apparatus in the frequency band F1.

15. The circuit in claim 14 further comprising using the estimation of the UL channel and calibration data of the hardware dependent components of the DL and UL channels to obtain an estimate of the DL channel from the second FDD apparatus to the first FDD apparatus in the frequency band F1 based on reciprocity of the over the air channel.

16. A method for acquiring the downlink channel information through the reciprocity of wireless channel in a FDD wireless network comprising reserving a time slot in the DL radio resource frame structure in the first frequency band (F1) for one or more UEs to transmit pilot or test signal(s) in the UL direction;

one or more UEs using the reserved time slot to transmit pilot or test signal(s) in the first frequency band F1;

a BS receiving and using the pilot or test signal(s) to estimate the DL channel information, and performing downlink MIMO beamforming using the estimate of the DL channel information.