Receiver with low power listen mode in a wireless local area network

• US 7,522,677 B2
• Filed: 10/21/2003
• Issued: 04/21/2009
• Est. Priority Date: 10/21/2003
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Liang, Jie
• Primary Examiner(s): TSE, YOUNG TOI
• Application Number:
  US10/690,446
• Publication Number:
  US 20050084037A1
• Time in Patent Office: 2,009 Days
• Field of Search: 375/316, 375/354, 375/216, 375/217, 375/144, 375/147, 375/148, 375/224, 375/340, 375/341, 375/349, 375/343, 455/13.4, 455/574, 455/456.4, 455/522, 455/212, 455/218, 370/338
• US Class Current: 375/316
• CPC Class Codes: H04L 27/0002 analog front ends; means for connecting modulators, demodulators or transceivers to a transmission line duplex arrangements H04L5/143
• CPC Class Codes: H04W 52/028 switching on or off only a part of the equipment circuit blocks
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A receiver for a wireless local area network, WLAN, having a low power listening mode of operation. The receiver includes two separate paths in the analog front end, AFE. One path includes a low resolution and low power analog to digital converter, ADC. The other path includes a high resolution and high power ADC. In listen mode, only the low resolution ADC is powered and provides inputs to a packet detector for identifying a barker code. When the correct barker code is received, the high resolution ADC is enabled and coupled to a receiver for receiving a payload in the data packet.

Claims

1. A wireless receiver having a low-power listen mode, comprising:

a first receiver path having a low resolution analog-to-digital converter for decoding a preamble to a wireless data packet and a second receiver path having a high resolution analog-to-digital converter for decoding a data packet payload, a packet detection logic to identify data packets directed to the wireless receiver; and

a switching logic coupled to the packet detection logic to select the first receiver path or the second receiver path depending on whether the packet detection logic has identified a data packet directed to the wireless receiver, wherein the first receiver path has a lower decoding resolution than the second receiver path.

2. The wireless receiver of claim 1 wherein the second receiver path is separated from the first receiver path.

3. The wireless receiver of claim 1 wherein the first receiver path requires less power to operate than the second receiver path.

4. The wireless receiver of claim 1 wherein the low resolution analog-to-digital converter is a 2-bit analog-to-digital converter.

5. The wireless receiver of claim 1 wherein the high resolution analog-to-digital converter is an 8-bit analog-to-digital converter.

6. The wireless receiver of claim 1 wherein the first receiver path uses barker-code detection to decode the preamble.

7. The wireless receiver of claim 6 wherein the switching logic selects the first receiver path until the data packet is identified and then selects the second receiver path to decode the data packet payload.

8. A wireless receiver having a low-power listen mode, comprising:

a first analog front end comprising a low resolution analog-to-digital converter for receiving and decoding a preamble to a wireless data packet and a second analog front end comprising a high resolution analog-to-digital converter for receiving and decoding a data packet payload;

a packet detection logic to identify whether the wireless data packet is directed to the wireless receiver; and

a switching logic coupled to the packet detection logic to select the first analog front end or the second analog front end depending on whether the packet detection logic has identified the data packet as being directed to the wireless receiver, wherein the first analog front end receives and decodes the preamble and the second analog front end receives and decodes the data packet payload, wherein the first analog front end has a lower decoding resolution than the second analog front end.

9. The wireless receiver of claim 8 wherein the first analog front end requires less power to operate than the second analog front end.

10. The wireless receiver of claim 8 wherein the low resolution analog-to-digital converter is a 2-bit analog-to-digital converter.

11. The wireless receiver of claim 8 wherein the high resolution analog-to-digital converter is an 8-bit analog-to-digital converter.

12. The wireless receiver of claim 8 wherein a first receiver path, coupled to the first analog front end, uses barker-code detection to decode the preamble.

13. The wireless receiver of claim 8 wherein the switching logic selects the first analog front end until the data packet is identified as being directed to the wireless receiver and then selects the second analog front end to receive the data packet payload.

14. A method for receiving data packets in a wireless receiver, comprising:

receiving radio frequency signals with a first receiver path comprising a low resolution analog-to-digital converter;

decoding signals received through the first receiver path to detect a code in a preamble of a received data packet;

upon detection of the code, switching to a second receiver path;

receiving a payload of the received data packet with the second receiver path comprising a high resolution analog-to-digital converter, wherein the first receiver path has a lower decoding resolution than the second receiver path; and

decoding the payload received through the second receiver path using the decoding resolution of the second receiver path.

15. The method of claim 14 further comprising switching back to the first receiver path when receiving of the payload is completed.

16. The method of claim 14 wherein the first receiver path requires less power than the second receiver path.

17. A wireless device that is adapted to receive data packets from another wireless device, comprising:

receiving means for receiving encoded information via a data packet, the receiving means comprising

a first decoding means comprising a low resolution analog-to-digital converter for decoding a preamble of the data packet, the receiving means further comprising a second decoding means comprising a high resolution analog-to-digital converter for decoding a payload of the data packet, and switching means for switching between the first and second decoding means, wherein the first decoding means has a lower decoding resolution than the second decoding means.