Method for minimizing receive packet processing for a personal computer implementation of a wireless local area network adapter

• US 7,577,122 B1
• Filed: 06/12/2003
• Issued: 08/18/2009
• Est. Priority Date: 06/18/2002
• Status: Active Grant

• Current Assignee: Intellectual Ventures I LLC (Intellectual Ventures LLC)
• Original Assignee: Xocyst Transfer AG LLC (Intellectual Ventures LLC)
• Inventors: Hoffmann, John Erich, Schultz, Richard Douglas
• Primary Examiner(s): Nguyen; Brian D
• Application Number:
  US10/460,684
• Time in Patent Office: 2,259 Days
• Field of Search: 370/252, 370/229, 370/216, 370/241, 370/503, 370/500, 370/392, 370/338, 370/349, 370/389, 370/394, 370/401, 370/465, 370/474, 375/224
• US Class Current: 370/338
• CPC Class Codes: H04L 27/0012 arrangements for identifying the type of modulation
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01

Abstract

A method and wireless local area network (WLAN) adapter for the reduction of receive packet processing in a communications system receiver. The method includes establishing a set of criteria which identifies a packet as one requiring demodulation. The method further includes detecting a packet preamble to trigger at least one waveform identification function and determining with the at least one waveform identification function of the detected packet meets an established criteria for demodulation. The established criteria may include at least one of data rate, modulation type, signal to noise ratio, or coding rate. If the detected packet meets the established criteria for demodulation, a host processor may be interrupted to begin demodulation.

Claims

1. A method for the reduction of receive packet processing in a communications system receiver comprising the steps of:

establishing a set of criteria which identifies a packet as one requiring demodulation;

detecting a packet preamble to trigger at least one waveform identification function;

determining with the at least one waveform identification function if said detected packet meets an established criteria for demodulation, the established criteria comprising at least one of data rate, modulation type, signal to noise ratio, or coding rate; and

interrupting a host processor to begin demodulation if said detected packet meets the established criteria for demodulation.

2. A method as in claim 1, wherein the waveform identification function determines a forward error correction encoding rate used in the packet.

3. A method as in claim 1, wherein the waveform identification function determines the modulation type used in the packet.

4. A method as in claim 1, wherein the waveform identification function utilizes the dynamics of an automatic gain control (AGC) response to estimate a received signal to noise ratio (SNR).

5. A method as in claim 1, wherein the waveform identification function operates on samples that remain in a time-domain representation.

6. A method as in claim 1, in which the waveform identification function operates on samples that have been converted to a frequency-domain representation.

7. A method as in claim 1, in which the waveform identification function operates on samples that exist in either time-domain or frequency domain representation.

8. A method as in claim 1, in which the communications system is wireless.

9. A method as in claim 1, in which the communications system is IEEE 802.11 wireless local area network (WLAN).

10. A method as in claim 1, in which the communications system is Bluetooth.

11. A method as in claim 1, in which the communications system is IEEE 802.12 wireless personal area network (PAN).

12. A method as in claim 1, in which the waveform identification function determines RATE bits of a SIGNAL field in an IEEE 802.11 PLCP header.

13. A method as in claim 1, in which the waveform identification function determines the modulation type used in DATA symbols of an IEEE 802.11 PPDU frame.

14. A method as in claim 1, in which the waveform identification function determines a convolutional encoder rate used to protect a DATA field of an IEEE 802.11 PPDU frame.

15. A wireless local area network (WLAN) adapter for use with a host processor, the WLAN adapter comprising:

a receive amplifier;

an analog-to-digital converter; and

a baseband processor, wherein the adapter is configured to (i) analyze received data from the analog-to-digital converter to detect a packet preamble and to trigger at least one waveform identification function (ii) determine whether the data contains information destined for the host processor by using a waveform detector to determine that the detected packet meets an established criteria for demodulation the established criteria comprising at least one of data rate, modulation type, signal to noise ratio, or coding rate and (iii) selectively transfer samples to the host processor when the data contains information destined for the host processor.

16. The WLAN adapter of claim 15, wherein the baseband processor comprises a preamble detector wherein the preamble detector is configured to determine whether the received data from the analog-to-digital converter contains valid preambles, and wherein the adapter is configured to selectively transfer samples to the host processor in the event that the preamble detector detects a valid preamble.

17. The WLAN adapter of claim 15, wherein the WLAN adapter further comprises a host processor interface wherein the host processor interface allows communication between the adapter and the host processor.

18. The WLAN adapter of claim 15, wherein the baseband processor comprises:

a convolutional encoder;

a modulation recognition device;

an automatic gain control (AGC) dynamics and noise floor comparison matching device; and

an information combiner, wherein the information combiner accepts inputs from the convolutional encoder, the modulation recognition device, and the AGC dynamics and noise floor comparison matching device in order to determine if the data contains information destined for the host processor.