Tag communications with access point
A method of establishing communication at a tag includes calculating a metric for each of a plurality of automatic frequency control (AFC) hypotheses where the plurality of AFC hypotheses correspond to a timing used by an access point; based on the calculated metrics, identifying one or more relevant AFC hypotheses; performing a check on a demodulated data stream identified using the one or more relevant AFC hypotheses; identifying a valid AFC hypothesis based at least in part on the check; and determining where a frame starts based at least in part on the check.
1. A method of establishing communication at a tag, the method comprising:
calculating a metric at a processor for each of a plurality of automatic frequency control (AFC) hypotheses, wherein the plurality of AFC hypotheses correspond to a timing used by an access point;
based on the calculated metrics, identifying one or more relevant AFC hypotheses;
performing a check on a demodulated data stream identified using the one or more relevant AFC hypotheses;
identifying a valid AFC hypothesis based at least in part on the check; and
determining where a frame starts based at least in part on the check.
2. The method of claim 1 , wherein the demodulated data stream is a single bit input from each of a plurality of analog-to-digital (ADC) modules.
3. The method of claim 1 , further comprising:
identifying frame timing by iterating over a multi-slot timing hypothesis; and
using the frame timing to identify a time slot in which the access point is broadcasting.
4. The method of claim 1 , wherein simultaneously evaluating the one or more relevant AFC hypotheses includes assigning the one or more relevant AFC hypotheses to a plurality of dedicated fingers.
5. The method of claim 1 , further comprising simultaneously evaluating the one or more relevant AFC hypotheses to identify a fine AFC hypothesis, wherein the fine AFC hypothesis is used in the check on the data stream.
6. The method of claim 1 , wherein the plurality of AFC hypotheses correspond to chip times four hypotheses for each of a plurality of coarse automatic frequency control values.
7. The method of claim 1 , wherein the check comprises a cyclic redundancy check.
8. A tag for communicating with an access point, the tag comprising:
a receiver, wherein the receiver is configured to receive a data stream from the access point; and
a processor in communication with the receiver, wherein the processor is configured to
calculate, based on the received data stream, a metric for each of a plurality of automatic frequency control (AFC) hypotheses;
identify one or more relevant AFC hypotheses based on the calculated metrics;
perform a check on a demodulated data stream identified using the one or more relevant AFC hypotheses;
identify a valid AFC hypothesis based at least in part on the check; and
determine where a frame starts based at least in part on the check.
9. The tag of claim 8 , wherein the calculated metrics are based at least in part on a pseudo-noise (PN) code which is unique to the tag.
10. The tag of claim 8 , wherein the processor is further configured to assign the one or more relevant AFC hypotheses to a plurality of dedicated fingers based at least in part on the calculated metrics.
11. The tag of claim 8 , wherein the processor is further configured to simultaneously evaluate the one or more relevant AFC hypotheses to identify a fine AFC hypothesis, wherein the fine AFC hypothesis is used in the check on the data stream.
12. The tag of claim 8 , wherein the demodulated data stream is a single bit input from each of a plurality of analog-to-digital (ADC) modules.
13. The tag of claim 8 , wherein the processor is further configured to provide a payload associated with the data stream to a medium access control layer of the tag.
14. The tag of claim 8 , wherein the plurality of AFC hypotheses correspond to chip times four hypotheses for each of a plurality of coarse automatic frequency control values.
15. A computer-readable medium having computer-readable instructions stored thereon, where, upon execution by a processor, the computer-readable instructions cause the processor to:
calculate at the processor, based on a received data stream, a metric for each of a plurality of automatic frequency control (AFC) hypotheses, wherein the plurality of AFC hypotheses correspond to a timing used by an access point;
identify one or more relevant AFC hypotheses based on the calculated metrics;
perform a check on a data stream identified using the one or more relevant AFC hypotheses;
identify a valid AFC hypothesis based at least in part on the check; and
determine where a frame starts based at least in part on the check.
16. The computer-readable medium of claim 15 , wherein the processor is further caused to assign the one or more relevant AFC hypotheses to a plurality of dedicated fingers based at least in part on the calculated metrics.
17. The computer-readable medium of claim 15 , the demodulated data stream is a single bit input from each of a plurality of analog-to-digital (ADC) modules.
18. The computer-readable medium of claim 15 , wherein the processor is further configured to simultaneously evaluate the one or more relevant AFC hypotheses to identify a fine AFC hypothesis, wherein the fine AFC hypothesis is used in the check on the data stream.
19. The computer-readable medium of claim 15 , wherein the check comprises a cyclic redundancy check.
20. The computer-readable medium of claim 15 , wherein the calculated metrics are based at least in part on a pseudo-noise (PN) code which is unique to the tag.