Beam-change indication for channel estimation improvement in wireless networks

• US 9,954,594 B2
• Filed: 03/07/2016
• Issued: 04/24/2018
• Est. Priority Date: 05/03/2012
• Status: Active Grant

• Current Assignee: MediaTek Singapore Pte. Ltd. (MediaTek, Inc.)
• Original Assignee: MediaTek Singapore Pte. Ltd. (MediaTek, Inc.)
• Inventors: Liu, Jianhan, Pare, Jr., Thomas Edward, Wang, Chao-Chun, Wang, James June-Ming, Hsu, YungPing
• Primary Examiner(s): Roberts, Brian
• Application Number:
  US15/062,403
• Publication Number:
  US 20160191136A1
• Time in Patent Office: 778 Days
• Field of Search: None
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0695 using beam selection
• CPC Class Codes: H04L 2025/03783 Details of reference signals
• 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 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition

Abstract

A method of channel estimation enhancement is provided. In a wireless communications system, a transmitting device transmits a long preamble frame comprising a first training field, a signal field, and a second training field. The signal field has a beam-change indicator bit indicates whether there is beam change between the first training field and the second training field. A receiving device receives the long preamble frame, performs a first channel estimation based on the first training field, and performs a second channel estimation based on the second training field. If the beam-change indicator bit indicates negative beam change, then the receiving device performs channel estimation enhancement by combining the first channel estimation and the second channel estimation. As a result, channel estimation performance is improved.

Claims

1. A method comprising:

applying a first beam-steering matrix to a training sequence and generating a first training field by a wireless device;

applying a second beam-steering matrix to the training sequence and generating a second training field by the wireless device;

inserting a beam-change indicator in a signal field, wherein the beam-change indicator indicates whether there is beam change between the first training field and the second training field; and

encoding the first training field, the signal field, and the second training field into a long preamble frame to be transmitted to a receiving device, wherein the signal field is transmitted after the first training field but before the second training field.

2. The method of claim 1, where the device determines the beam-change indicator by comparing the first beam-steering matrix and the second beam-steering matrix.

3. The method of claim 2, wherein the long preamble is transmitted over K subcarriers, wherein K is a positive integer, and wherein the beam-change indicator is determined by comparing the beam-steering matrixes for each of the subcarriers.

4. The method of claim 3, wherein the beam-change indicator is set to zero if the beam-steering matrixes are equal for all subcarriers.

5. The method of claim 1, wherein the first beam-steering matrix is applied to an omni portion of the training sequence.

6. The method of claim 1, wherein the second beam-steering matrix is applied to a data portion of the training sequence.

7. The method of claim 1, wherein the first beam-steering matrix is an identity matrix to achieve omnidirectional transmission.

8. The method of claim 1, wherein the second beam-steering matrix is a beamforming matrix with precoding weights to achieve directional transmission based on channel sounding feedback information.

9. The method of claim 1, wherein the beam-change indicator also indicates whether to apply channel smoothing.

10. A wireless device, comprising:

a first training field generator circuit that generate a first training field by applying a first set of beam-steering matrices to a training sequence;

a second training field generator circuit that generates a second training field by applying a second set of beam-steering matrices to the training sequence;

a signal field generator circuit that inserts a beam-change indicator in a signal field, wherein the beam-change indicator indicates whether there is beam change between the first training field and the second training field;

an encoder circuit that encodes the first training field, the signal field, and the second training field into a long preamble frame; and

a radio frequency transmitter that transmits the long preamble frame in a wireless communication network, wherein the signal field is transmitted after the first training field but before the second training field.

11. The wireless device of claim 10, where the device comprises a processor that determines the beam-change indicator by comparing the first beam-steering matrix and the second beam-steering matrix.

12. The wireless device of claim 11, wherein the long preamble is transmitted over K subcarriers, wherein K is a positive integer, and wherein the beam-change indicator is determined by comparing the beam-steering matrixes for each of the subcarriers.

13. The wireless device of claim 12, wherein the beam-change indicator is set to zero if the beam-steering matrixes are equal for all subcarriers.

14. The wireless device of claim 10, wherein the first beam-steering matrix is applied to an omni portion of the training sequence.

15. The wireless device of claim 10, wherein the second beam-steering matrix is applied to a data portion of the training sequence.

16. The wireless device of claim 10, wherein the first beam-steering matrix is an identity matrix to achieve omnidirectional transmission.

17. The wireless device of claim 10, wherein the second beam-steering matrix is a beamforming matrix with precoding weights to achieve directional transmission based on channel sounding feedback information.

18. The wireless device of claim 10, wherein the beam-change indicator also indicates whether to apply channel smoothing.