Efficient auto detection for next generation WLAN
An auto-detection scheme may be applied to a physical layer (PHY) preamble of a communications packet, such as an 802.11 packet, to identify which generation of a communication standard was used to generate the packet. A packet of a wireless transmission may be received by a wireless device. The packet may include a PHY preamble, including a first field, such as a legacy long training field (L-LTF), and a second, subsequent field, such as a non-legacy Signal field. The wireless device may determine that the first field is encoded using a Fast-Fourier Transform (FFT) of a first size, and that the second field is encoded using a FFT of a second, different size. This determining may identify a generation of the communication standard used to generate the packet. In response to the determining, the wireless device may decode the packet according to the identified generation of the communication standard.
1. A wireless communication device comprising: at least one processor; a memory storing software instructions executable by the at least one processor; wireless communication circuitry communicatively coupled to the at least one processor; wherein the wireless communication device is configured to: receive a packet of a wireless transmission, the packet comprising a physical layer (PHY) preamble comprising a first field and a second, subsequent field; determine whether the first field and the second field are encoded using Fast-Fourier Transforms (FFTs) of the same size; in response to determining that the first field and the second field are encoded using FFTs of the same size, decode the packet according to a first generation of a communication standard; and in response to determining that the first field and the second filed are not encoded using FFTs of the same size, decode the packet according to a second, different generation of the communication standard; wherein the wireless communication device is further configured to: in response to determining that the second field is encoded using a larger FFT than the first field: estimate, using training information comprised in the first field, a communication channel through which the wireless transmission is received, wherein a number of channel estimation points resulting from the estimating is a function of the size of the FFT with which the first field is encoded; and interpolate additional channel estimation points for decoding the second field.
2. The wireless communication device of claim 1 , wherein the first field comprises a legacy long training field (L-LTF), and the second field comprises a non-legacy Signal field.
3. The wireless communication device of claim 1 , wherein the communication standard is the 802.11 communication standard.
4. The wireless communication device of claim 1 , wherein the determining whether the first field and the second field are encoded using FFTs of the same size comprises: decoding the first field and the second field using an Inverse Fast-Fourier Transform (IFFT) of a first size; and determining whether a data validity check including data from the first field and the second field decoded using the IFFT of the first size indicates an error.
5. The wireless communication device of claim 1 , wherein the determining whether the first field and the second field are encoded using FFTs of the same size further comprises: decoding the first field using an IFFT of a first size and decoding the second field using an IFFT of a second size; and determining that a data validity check including data from the second field decoded using the IFFT of the second size does not indicate an error.
6. A method, comprising: by a wireless device: receiving a packet of a wireless transmission, wherein the packet comprises a physical layer (PHY) preamble, wherein the PHY preamble comprises a first field and a second, subsequent field; determining that the first field is encoded using a Fast-Fourier Transform (FFT) of a first size and the second field is encoded using a FFT of a second, different size; decoding the packet according to a particular generation of a communication standard, wherein the particular generation of the communication standard is identified based on the determining; wherein the FFT of the second size is larger than the FFT of the first size, the method further comprising: estimating, using training information comprised in the first field, a communication channel through which the wireless transmission is received, wherein a number of channel estimation points resulting from the estimating is a function of the size of the FFT with which the first field is encoded; interpolating additional channel estimation points for decoding the second field with the FFT of the second size.
7. The method of claim 6 , further comprising: by the wireless device: receiving a second packet of a wireless transmission, wherein the second packet comprises a second PHY preamble, wherein the second PHY preamble comprises a third field and a fourth, subsequent field; determining that both the third field and the fourth field are encoded using a FFT of the first size; decoding the second packet according to a different generation of the communication standard, wherein the different generation of the communication standard is identified based at least partly on the determining that both the third field and the fourth field are encoded using a FFT of the first size.
8. The method of claim 7 , wherein the first field and the third field each comprise a legacy long training field (L-LTF), and the second field and the fourth field each comprise a non-legacy Signal field.
9. The method of claim 6 , wherein the communication standard is the 802.11 communication standard.
10. The method of claim 6 , wherein the determining that the second field is encoded using a FFT of the second size comprises: decoding the second field using an Inverse Fast-Fourier Transform (IFFT) of the first size; and determining that a data validity check including data from the second field decoded using the IFFT of the first size indicates an error.
11. The method of claim 6 , wherein the determining that the second field is encoded using a FFT of the second size further comprises: decoding the second field using an Inverse Fast-Fourier Transform (IFFT) of the second size; and determining that a data validity check including data from the second field decoded using the IFFT of the second size does not indicate an error.
12. A non-transitory computer-readable medium storing software instructions executable by a processor of a wireless communication device, the software instructions configured to cause the wireless communication device to: receive a packet of a wireless transmission, wherein the packet comprises a physical layer (PHY) preamble, wherein the PHY preamble comprises a first field and a second, subsequent field; determine that the first field is encoded using a Fast-Fourier Transform (FFT) of a first size and the second field is encoded using a FFT of a second, different size; decode the packet according to a particular generation of a communication standard, wherein the particular generation of the communication standard is identified based on the determining; wherein the FFT of the second size is larger than the FFT of the first size, wherein the software instructions are further configured to cause the wireless communication device to: estimate, using training information comprised in the first field, a communication channel through which the wireless transmission is received, wherein a number of channel estimation points resulting from the estimating is a function of the size of the FFT with which the first field is encoded; interpolate additional channel estimation points for decoding the second field with the FFT of the second size.
13. The non-transitory computer-readable medium of claim 12 , wherein the software instructions are further configured to cause the wireless communication device to: receive a second packet of a wireless transmission, wherein the second packet comprises a second PHY preamble, wherein the second PHY preamble comprises a third field and a fourth, subsequent field; determine that both the third field and the fourth field are encoded using a FFT of the first size; decode the second packet according to a different generation of the communication standard, wherein the different generation of the communication standard is identified based at least partly on the determining that both the third field and the fourth field are encoded using a FFT of the first size.
14. The non-transitory computer-readable medium of claim 13 , wherein the first field and the third field each comprise a legacy long training field (L-LTF), and the second field and the fourth field each comprise a non-legacy Signal field.
15. The non-transitory computer-readable medium of claim 12 , wherein the communication standard is the 802.11 communication standard.
16. The non-transitory computer-readable medium of claim 12 , wherein, in determining that the second field is encoded using a FFT of the second size, the software instructions are further configured to cause the wireless communication device to: decode the second field using an Inverse Fast-Fourier Transform (IFFT) of the first size; and determine that a data validity check including data from the second field decoded using the IFFT of the first size indicates an error.
17. The non-transitory computer-readable medium of claim 12 , wherein, in determining that the second field is encoded using a FFT of the second size, the software instructions are further configured to cause the wireless communication device to: decoding the second field using an Inverse Fast-Fourier Transform (IFFT) of the second size; and determining that a data validity check including data from the second field decoded using the IFFT of the second size does not indicate an error.