METHOD AND SYSTEM TO DETECT PACKETS OF DIFFERENT FORMATS IN A WIRELESS RECEIVER

1 . A method for detecting packets of different formats in a receiver comprising:

initializing the receiver to be in a legacy mode;

receiving at least one data symbol by the receiver; and

detecting if there is a high throughput (HT) signal field within a data packet; and

determining the format of the data packet based upon the detection of a high throughput signal field.

2 . The method of claim 1 wherein the different formats comprises a green field format, a mixed mode format and a legacy mode format.

3 . The method of claim 1 wherein if the HT signal field is detected within a first predetermined time period, a first HT format is detected.

4 . The method of claim 3 wherein if the data rate from a low throughput signal field is at a predetermined value and a HT signal field is detected within a second predetermined period after the first predetermined true period, a second HT format is detected; and wherein if neither of the above conditions are met, the receiver remains in a legacy mode.

5 . The method of claim 1 wherein the HT signal field is detected once a binary phase shift keying (BPSK) modulation is appended to the packet.

6 . The method of claim 1 wherein the detection compares equalizer symbols power in the I and Q signals in a constellation diagram.

7 . The method of claim 1 wherein a threshold is provided based upon the signal to noise ratio (SNR) of the HT signal field to ensure that the packets are properly detected.

8 . The method of claim 1 wherein a proper range of detection is based upon the S>α·N where S is the signal power, N is the noise power, and α is the signal to noise ratio.

9 . The method of claim 8 wherein the detection threshold comprises (2·α+1).

10 . The method of claim 9 wherein a proper range of the detection threshold is between 1.5 and 2.

11 . A system for detecting packets of different formats in a receiver, comprising:

means for initializing the receiver to be in a legacy mode;

means for receiving at least one data symbol by the receiver; and

means for detecting if there is a high throughput (HT) signal field within a data packet; and

means for determining the format of the data packet based upon the detection of a high throughput signal field.

12 . The system of claim 11 wherein the different formats comprises a green field format, a mixed mode format and a legacy mode format.

13 . The system of claim 11 wherein if the HT signal field is detected within a first predetermined time period, a first HT format is detected.

14 . The system of claim 13 wherein if that data rate from a low throughput signal field is at a predetermined value and a HT signal field is detected within a second predetermined period after the first predetermined true period, a second HT format is detected; and wherein if neither of the above conditions are met, the receiver remains in a legacy mode.

15 . The system of claim 11 wherein the HT signal field is detected once a binary phase shift keying (BPSK) modulation is appended to the packet.

16 . The system of claim 11 wherein the detection compares equalizer symbols power in the I and Q signals in a constellation diagram.

17 . The system of claim 11 wherein a threshold is provided based upon the signal to noise ratio (SNR) of the HT signal field to ensure that the packets are properly detected.

18 . The system of claim 1 wherein a proper range of detection is based upon the S>α·N where S is the signal power, N is the noise power, and α is the signal to noise ratio.

19 . The system of claim 18 wherein the detection threshold comprises (2·α+1).

20 . The system of claim 19 wherein a proper range of the detection threshold is between 1.5 and 2.