Interference rejection in wireless receivers

• US 7,653,035 B2
• Filed: 12/20/2004
• Issued: 01/26/2010
• Est. Priority Date: 12/20/2004
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Lin, Xintian E., Li, Qinghua, Chen, Camille C.
• Primary Examiner(s): Ngo; Ricky
• Assistant Examiner(s): HAN, CLEMENCE S
• Application Number:
  US11/017,517
• Publication Number:
  US 20060133259A1
• Time in Patent Office: 1,863 Days
• Field of Search: None
• US Class Current: 370/338
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters

Abstract

The effects of interference are mitigated in a wireless system through update noise variance estimates. Noise variance estimates may be update after the reception of a preamble in an OFDM receiver. Noise variance estimates may include averages of signal energy over multiple symbols in one OFDM tone and over multiple OFDM tones. A co-located wireless personal area network (WPAN) interface may signal its presence a wireless local area network (WLAN) interface, which may select a noise variance estimate algorithm based therein.

Claims

1. A method comprising:

updating a noise variance estimate during the reception of a data portion of a packet in an orthogonal frequency division multiplexing (OFDM) receiver wherein the noise variance estimate include an average signal energy over multiple symbols in multiple OFDM tones;

determining whether a Bluetooth complaint device is co-located with the OFDM receiver through direct communication using a least one electrical conductor between the Bluetooth complaint device and the OFDM receiver; and

selecting an algorithm to re-estimate the noise variance based on whether a Bluetooth complaint device is co-located.

2. The method of claim 1, further comprising estimating soft bits using the updated noise variance.

3. A method comprising:

updating a noise variance estimate during the reception of a data portion of a packet in an orthogonal frequency division multiplexing (OFDM) receiver wherein the noise variance estimate includes an average signal energy over multiple symbols in a single OFDM tone;

determining whether a Bluetooth complaint device is co-located with the OFDM receiver through direct communication using a least one electrical conductor between the Bluetooth complaint device and the OFDM receiver; and

selecting an algorithm to re-estimate the noise variance based on whether a Bluetooth complaint device is co-located.

4. A method comprising:

receiving a signal having a preamble in an orthogonal frequency division multiplexing (OFDM) system;

estimating a noise variance for multiple frequency sub-carrier ion the OFDM system;

receiving a signal having data in the OFDM system;

determining whether a Bluetooth complaint device is co-located with the OFDM receiver through direct communication using a least one electrical conductor between the Bluetooth complaint device and the OFDM receiver;

selecting an algorithm to re-estimate the noise variance based on whether a Bluetooth complaint device is co-located; and

re-estimating the noise variance by averaging signal energy over multiple symbols in the multiple frequency sub-carrier.

5. The method of claim 4 further comprising estimating soft bits from the re-estimated noise variance.

6. The method of claim 4 wherein re-estimating the noise variance comprises re-estimating a noise variance for each frequency sub-carrier in the OFDM system.

7. An article comprising a machine-readable medium adapted to hold instructions that when accessed result in a machine determining whether Bluetooth complaint device is co-located with an OFDM receiver through direct communication using a least one electrical conductor between the Bluetooth complaint device and the OFDM receiver, continuously estimating a noise variance for each tone in a received OFDM signal wherein estimating a noise variance comprises averaging received signal energy over a plurality of received symbols in one OFDM tone, wherein estimating a noise variance comprises using a first method to estimate the noise variance when the Bluetooth interface is co-located with the OFDM receiver, and using a second method to estimate the noise variance when no Bluetooth interface id co-located with the OFDM receiver.

8. The article of claim 7 wherein the second method comprises averaging received signal energy over a plurality of OFDM tones.

9. An electronic system comprising:

a wireless personal area network (WPAN) interface;

a wireless local area network (WLAN) interface that utilizes orthogonal frequency division multiplexing (OFDM);

and electrical conductor to form a signal path from the WPAN interface to the WLAN interface to indicate the presence of the WPAN interface in the electronic system; and

a memory storage element to hold instructions that when accessed result in updating a noise variance for a received WLAN signal, wherein the noise variance describes the received WLAN signal for a time period other than a time during which a preamble is received.

10. The electronic system of claim 9 wherein the WPAN interface comprises a Bluetooth compatible device.

11. The electronic system of claim 9 wherein the WLAN interface comprises an 802.11 compatible device.

12. The electronic system of claim 9 wherein the memory storage element further holds instructions that when accessed result in updating the noise variance using a different algorithm in response to the presence of the WPAN interface.