Single stream phase tracking during channel estimation in a very high throughput wireless MIMO communication system

Patent metadata

Field	Value
Publication number	US-9935750-B2
Application number	US-201414537829-A
Country	US
Kind code	B2
Filing date	Nov 10, 2014
Priority date	Aug 26, 2010
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

In a multiple-input, multiple-output (MIMO) system, a wireless node's receive chain demodulation function is enhanced to include phase tracking. VHT Long Training Fields (LTFs) embedded in a frame preamble are used for phase tracking. Single stream pilot tones are added during transmission of VHT-LTFs. A receiver estimates the channel using the pilot tones in a first set of LTFs. A second set of LTFs are used to estimate the phase of the pilot tones using the estimated channel. The phase estimation is continuously applied to other received data tones throughout the VHT-LTFs of data symbols. Phase errors due to PLL mismatches and phase noise are reduced at reception, leading to better signal to noise ratio for different levels of drift and frequency offset. Further, MIMO channel estimation is more accurate, improving the overall wireless network when the accurate MIMO channel estimation data participates in calibration and handshake between wireless nodes.

First claim

We claim:

1. A wireless communication apparatus comprising:
a processor configured to embed a set of identical information within each of a plurality of very-high throughput long-training-fields (VHT-LTFs) included in a preamble of a data frame;
a modulator configured to distribute the plurality of VHT-LTFs and payload data of the data frame into a plurality of spatial streams; and
a plurality of transceivers configured to output the plurality of spatial streams for transmission via a plurality of antennas.

2. The apparatus of claim 1 , wherein the set of identical information comprises a single stream of identical pilot tones.

3. The apparatus of claim 1 , wherein the modulator is configured to distribute the plurality of VHT-LTFs and payload data using orthogonal frequency division multiplexing (OFDM).

4. The apparatus of claim 1 , wherein the preamble of the data frame contains one VHT-LTF for each receive antenna of a device configured to receive the plurality of spatial streams.

5. The apparatus of claim 1 , further comprising a spatial processor to apply a per-stream cyclic shift delay to each of the plurality of spatial streams.

6. A method for wireless communication, comprising:
embedding a set of identical information within each of a plurality of very-high throughput long-training-fields (VHT-LTFs) included in a preamble of a data frame;
distributing the plurality of VHT-LTFs and payload data of the data frame into a plurality of spatial streams; and
outputting the plurality of spatial streams for transmission via a plurality of antennas.

7. The method of claim 6 , wherein the set of identical information comprises a single stream of identical pilot tones.

8. The method of claim 6 , wherein the plurality of VHT-LTFs and payload data are distributed using orthogonal frequency division multiplexing (OFDM).

9. The method of claim 6 , wherein the preamble of the data frame contains one VHT-LTF for each receive antenna of a device configured to receive the plurality of spatial streams.

10. The method of claim 6 , further comprising:
applying a per-stream cyclic shift delay to each of the spatial streams prior to transmission.

11. A non-transitory computer readable medium comprising instructions that, when executed by an apparatus, cause the apparatus to:
embed a set of identical information within each of a plurality of very-high throughput long-training-fields (VHT-LTFs) included in a preamble of a data frame;
distribute the plurality of VHT-LTFs and payload data of the data frame into a plurality of spatial streams; and
output the plurality of spatial streams for transmission via a plurality of antennas.

12. The non-transitory computer readable medium of claim 11 , wherein the set of identical information comprises a single stream of pilot tones.

13. The non-transitory computer readable medium of claim 11 , wherein the plurality of VHT-LTFs and payload data are distributed using orthogonal frequency division multiplexing (OFDM).

14. The non-transitory computer readable medium of claim 11 , wherein the preamble of the data frame contains one VHT-LTF for each receive antenna of a device configured to receive the plurality of spatial streams.

15. The non-transitory computer readable medium of claim 11 , wherein execution of the instructions further causes the apparatus to apply a per-stream cyclic shift delay to each of the plurality of spatial streams.

Assignees

• Qualcomm Inc

Inventors

• Shi Kai
• Zhang Ning

Classifications

• H04B7/0421 Primary

  utilizing implicit feedback, e.g. steered pilot signals · CPC title

• H04L27/2657

  Carrier synchronisation · CPC title

• H04B7/0413 Primary

  MIMO systems · CPC title

• H04L25/0204

  of multiple channels · CPC title

• H04L27/2672

  Frequency domain · CPC title