Channel estimation for a WLAN through increased use of preamble
A system including a receiver to receive, over a wireless channel, a packet including a preamble portion that includes a plurality of training fields and a first signal field and a controller to generate a first estimate of the wireless channel based on one or more of the plurality of training fields, and decode the first signal field based on the first estimate. Subsequent to decoding the first signal field, the controller re-encodes the first signal field to generate a second signal field. The controller verifies whether the first signal field was properly decoded by comparing the second signal field to the first signal field prior to being decoded. In response to the first signal field being correctly decoded, the controller generates a second estimate of the wireless channel based on the first signal field as decoded. The second estimate is usable to refine the first estimate.
1. A system, comprising:
a receiver configured to receive, over a wireless channel, a packet including a preamble portion, wherein the preamble portion includes (i) a plurality of training fields and (ii) a first signal field; and
a controller configured to
generate a first estimate of the wireless channel based on one or more of the plurality of training fields,
decode the first signal field based on the first estimate of the wireless channel,
subsequent to decoding the first signal field, re-encode the first signal field to generate a second signal field,
verify whether the first signal field was properly decoded by comparing (i) the second signal field to (ii) the first signal field prior to being decoded, and
in response to the first signal field being determined to have been correctly decoded based on the comparing of (i) the second signal field to (ii) the first signal field prior to being decoded, generate a second estimate of the wireless channel based on the first signal field as decoded, wherein the second estimate of the wireless channel is usable to refine the first estimate of the wireless channel.
2. The system of claim 1 , wherein the first signal field is located between two of the plurality of training fields.
3. The system of claim 1 , wherein the controller is configured to generate a third estimate of the wireless channel based on (i) the first estimate of the wireless channel and (ii) the second estimate of the wireless channel, and wherein the third estimate of the wireless channel corresponds to a refinement of the first estimate of the wireless channel.
4. The system of claim 3 , wherein the controller is configured to decode data in a data portion of the packet based on the third estimate of the wireless channel.
5. The system of claim 3 , wherein the controller is further configured to:
initially decode data in a data portion of the packet based on the first estimate of the wireless channel; and
subsequent to the second estimate of the wireless channel being generated, decode data in the data portion of the packet based on both of (i) the first estimate of the wireless channel and (ii) the second estimate of the wireless channel.
6. The system of claim 1 , wherein:
the preamble portion further comprises a field between the first signal field and one of the plurality of training fields, and
the controller is configured to generate a third estimate of the wireless channel based on (i) the first estimate of the wireless channel, (ii) the second estimate of the wireless channel, and (iii) the field.
7. A system, comprising:
a receiver configured to, over a wireless channel, receive a packet including a preamble portion, wherein the preamble portion includes (i) a first training field and (ii) a second training field; and
a controller configured to
generate a first estimate of the wireless channel based on the first training field,
generate a second estimate of the wireless channel based on a first portion of the second training field, and
generate a third estimate of the wireless channel based on (i) the first estimate of the wireless channel and (ii) the second estimate of the wireless channel.
8. The system of claim 7 , wherein the first training field is longer than the second training field.
9. The system of claim 7 , wherein the second training field includes a Legacy Short Training Field used in Greenfield mode.
10. The system of claim 7 , wherein the controller is configured to use a second portion of the second training field for synchronization or to adjust a gain of the receiver.
11. A method, comprising:
receiving, at a receiver, over a wireless channel, a packet including a preamble portion, wherein the preamble portion includes (i) a plurality of training fields and (ii) a first signal field;
generate a first estimate of the wireless channel based on one or more of the plurality of training fields,
decoding the first signal field based on the first estimate of the wireless channel;
subsequent to decoding the first signal field, re-encoding the first signal field to generate a second signal field;
verifying whether the first signal field was properly decoded by comparing (i) the second signal field to (ii) the first signal field prior to being decoded; and
in response to the first signal field being determined to have been correctly decoded based on the comparing of (i) the second signal field to (ii) the first signal field prior to being decoded, generating a second estimate of the wireless channel based on the first signal field as decoded, wherein the second estimate of the wireless channel is usable to refine the first estimate of the wireless channel.
12. The method of claim 11 , wherein the first signal field is located between two of the plurality of training fields.
13. The method of claim 11 , further comprising generating a third estimate of the wireless channel based on (i) the first estimate of the wireless channel and (ii) the second estimate of the wireless channel, and wherein the third estimate of the wireless channel corresponds to a refinement of the first estimate of the wireless channel.
14. The method of claim 13 , further comprising decoding data in a data portion of the packet based on the third estimate of the wireless channel.
15. The method of claim 13 , further comprising:
initially decoding data in a data portion of the packet based on the first estimate of the wireless channel; and
subsequent to the second estimate of the wireless channel being generated, decoding data in the data portion of the packet based on both of (i) the first estimate of the wireless channel and (ii) the second estimate of the wireless channel.
16. The method of claim 11 , wherein the preamble portion further comprises a field between the first signal field and one of the plurality of training fields, the method further comprising:
generating a third estimate of the wireless channel based on (i) the first estimate of the wireless channel, (ii) the second estimate of the wireless channel, and (iii) the field.
17. A method, comprising:
receiving, at a receiver, over a wireless channel, a packet including a preamble portion, wherein the preamble portion includes (i) a first training field and (ii) a second training field;
generating a first estimate of the wireless channel based on the first training field;
generating a second estimate of the wireless channel based on a first portion of the second training field; and
generating a third estimate of the wireless channel based on (i) the first estimate of the wireless channel and (ii) the second estimate of the wireless channel.
18. The method of claim 17 , wherein the first training field is longer than the second training field.
19. The method of claim 17 , wherein the second training field includes a Legacy Short Training Field used in Greenfield mode.
20. The method of claim 17 , further comprising using a second portion of the second training field for synchronization or to adjust a gain of the receiver.