Two-way ranging messaging scheme

1. A method of wireless communication, comprising:

transmitting a first packet from a first apparatus to a second apparatus;

receiving a second packet from the second apparatus as a result of the transmission of the first packet;

transmitting a third packet from the first apparatus to the second apparatus after the reception of the second packet;

determining a first time value associated with the reception of the second packet and a second time value associated with the transmission of the third packet;

receiving information from the second apparatus, wherein the information is indicative of a third time value associated with the transmission of the second packet and a fourth time value associated with the reception of the third packet;

determining a distance between the first apparatus and the second apparatus based on the first time value, the second time value, and the received information;

transmitting a fourth packet from the first apparatus to the second apparatus;

receiving a fifth packet from the second apparatus, wherein the fifth packet comprises a first symbol sequence for gain control at the first apparatus; and

determining a gain level for the reception of the second packet based on the first symbol sequence.

2. The method of claim 1 , wherein the third packet is transmitted a defined period of time after the transmission of the first packet.

3. The method of claim 1 , wherein:

the second packet comprises a second symbol sequence for a leading edge detection operation at the first apparatus; and

the determination of the first time value comprises detecting a leading edge associated with the second symbol sequence and determining a time of arrival of the leading edge.

4. The method of claim 3 , wherein:

the third packet comprises a third symbol sequence for a leading edge detection operation at the second apparatus; and

the third symbol sequence comprises the beginning of the third packet.

5. The method of claim 1 , wherein the transmission of the first packet provides a timing indication for triggering the second apparatus to transmit the second packet.

6. The method of claim 1 , wherein the fifth packet is received as a result of the transmission of the fourth packet.

7. The method of claim 1 , wherein:

the fourth packet comprises a second symbol sequence for gain control at the second apparatus; and

the fourth packet is transmitted a defined period of time before the transmission of the first packet.

8. The method of claim 7 , wherein the fourth packet further comprises a third symbol sequence for clock drift estimation at the second apparatus.

9. The method of claim 1 , further comprising:

initiating a ranging operation at the first apparatus; and

initiating the gain control at the first apparatus as a result of the initiation of the ranging operation at the first apparatus.

10. The method of claim 1 , further comprising:

initiating a ranging operation at the first apparatus; and

establishing at least one ranging channel as a result of the initiation of the ranging operation at the first apparatus, wherein the at least one ranging channel is established for the transmission of at least the first and third packets and the reception of at least the second packet.

11. The method of claim 10 , wherein the establishment of the at least one ranging channel comprises defining at least one of the group consisting of: a pulse repetition period and a pulse time hopping sequence.

12. An apparatus for wireless communication, comprising:

a transmitter configured to transmit a first packet to another apparatus;

a receiver configured to receive a second packet from the another apparatus as a result of the transmission of the first packet, wherein the transmitter is further configured to transmit a third packet to the another apparatus after the reception of the second packet;

a ranging controller configured to determine a first time value associated with the reception of the second packet and a second time value associated with the transmission of the third packet, wherein the ranging controller is further configured to determine a distance between the apparatus and the another apparatus based on the first time value, the second time value, and information received from the another apparatus that is indicative of a third time value associated with the transmission of the second packet and a fourth time value associated with the reception of the third packet, wherein:

the transmitter is further configured to transmit a fourth packet to the another apparatus;

the receiver is further configured to receive a fifth packet from the another apparatus;

the fifth packet comprises a first symbol sequence for gain control at the apparatus; and

a gain controller configured to determine a gain level for the reception of the second packet based on the first symbol sequence.

13. The apparatus of claim 12 , wherein the third packet is transmitted a defined period of time after the transmission of the first packet.

14. The apparatus of claim 12 , wherein:

the second packet comprises a second symbol sequence for a leading edge detection operation at the apparatus; and

the determination of the first time value comprises detecting a leading edge associated with the second symbol sequence and determining a time of arrival of the leading edge.

15. The apparatus of claim 14 , wherein:

the third packet comprises a third symbol sequence for a leading edge detection operation at the another apparatus; and

the third symbol sequence comprises the beginning of the third packet.

16. The apparatus of claim 12 , wherein the transmission of the first packet provides a timing indication for triggering the another apparatus to transmit the second packet.

17. The apparatus of claim 12 , wherein the fifth packet is received as a result of the transmission of the fourth packet.

18. The apparatus of claim 12 , wherein:

the fourth packet comprises a second symbol sequence for gain control at the another apparatus; and

the fourth packet is transmitted a defined period of time before the transmission of the first packet.

19. The apparatus of claim 18 , wherein the fourth packet further comprises a third symbol sequence for clock drift estimation at the another apparatus.

20. The apparatus of claim 12 , wherein:

the ranging controller is further configured to initiate a ranging operation; and

the gain controller is further configured to initiate the gain control at the apparatus as a result of the initiation of the ranging operation.

21. The apparatus of claim 12 , wherein:

the ranging controller is further configured to initiate a ranging operation;

the apparatus further comprises a communication controller configured to establish at least one ranging channel as a result of the initiation of the ranging operation; and

the at least one ranging channel is established for the transmission of at least the first and third packets and the reception of at least the second packet.

22. The apparatus of claim 21 , wherein the establishment of the at least one ranging channel comprises defining at least one of the group consisting of: a pulse repetition period and a pulse time hopping sequence.

23. An apparatus for wireless communication, comprising:

means for transmitting a first packet to another apparatus;

means for receiving a second packet from the another apparatus as a result of the transmission of the first packet, wherein the means for transmitting is configured to transmit a third packet to the another apparatus after the reception of the second packet;

means for determining a first time value associated with the reception of the second packet and a second time value associated with the transmission of the third packet;

means for determining a distance between the apparatus and the another apparatus based on the first time value, the second time value, and information received from the another apparatus that is indicative of a third time value associated with the transmission of the second packet and a fourth time value associated with the reception of the third packet, wherein:

the means for transmitting is configured to transmit a fourth packet to the another apparatus;

the means for receiving is configured to receive a fifth packet from the another apparatus;

the fifth packet comprises a first symbol sequence for gain control at the apparatus; and

means for determining a gain level for the reception of the second packet based on the first symbol sequence.

24. The apparatus of claim 23 , wherein the third packet is transmitted a defined period of time after the transmission of the first packet.

25. The apparatus of claim 23 , wherein:

the second packet comprises a second symbol sequence for a leading edge detection operation at the apparatus; and

the determination of the first time value comprises detecting a leading edge associated with the second symbol sequence and determining a time of arrival of the leading edge.

26. The apparatus of claim 25 , wherein:

the third packet comprises a third symbol sequence for a leading edge detection operation at the another apparatus; and

the third symbol sequence comprises the beginning of the third packet.

27. The apparatus of claim 23 , wherein the transmission of the first packet provides a timing indication for triggering the another apparatus to transmit the second packet.

28. The apparatus of claim 23 , wherein the fifth packet is received as a result of the transmission of the fourth packet.

29. The apparatus of claim 23 , wherein:

the fourth packet comprises a second symbol sequence for gain control at the another apparatus; and

the fourth packet is transmitted a defined period of time before the transmission of the first packet.

30. The apparatus of claim 29 , wherein the fourth packet further comprises a third symbol sequence for clock drift estimation at the another apparatus.

31. The apparatus of claim 23 , further comprising:

means for initiating a ranging operation; and

means for initiating the gain control at the apparatus as a result of the initiation of the ranging operation.

32. The apparatus of claim 23 , further comprising:

means for initiating a ranging operation; and

means for establishing at least one ranging channel as a result of the initiation of the ranging operation; wherein the at least one ranging channel is established for the transmission of at least the first and third packets and the reception of at least the second packet.

33. The apparatus of claim 32 , wherein the establishment of the at least one ranging channel comprises defining at least one of the group consisting of: a pulse repetition period and a pulse time hopping sequence.

34. A computer-program product for wireless communication, comprising:

computer-readable storage device comprising codes executable to:

transmit a first packet from a first apparatus to a second apparatus;

receive a second packet from the second apparatus as a result of the transmission of the first packet;

transmit a third packet from the first apparatus to the second apparatus after the reception of the second packet;

determine a first time value associated with the reception of the second packet and a second time value associated with the transmission of the third packet;

receive information from the second apparatus, wherein the information is indicative of a third time value associated with the transmission of the second packet and a fourth time value associated with the reception of the third packet;

determine a distance between the first apparatus and the second apparatus based on the first time value, the second time value, and the received information;

transmit a fourth packet from the first apparatus to the second apparatus;

receive a fifth packet from the second apparatus, wherein the fifth packet comprises a first symbol sequence for gain control at the first apparatus; and

determine a gain level for the reception of the second packet based on the first symbol sequence.

35. A headset, comprising:

a transmitter configured to transmit a first packet to an apparatus;

a receiver configured to receive a second packet from the apparatus as a result of the transmission of the first packet, wherein the transmitter is further configured to transmit a third packet to the apparatus a defined period of time after the reception of the second packet;

a ranging controller configured to determine a first time value associated with the reception of the second packet and a second time value associated with the transmission of the third packet, wherein the ranging controller is further configured to determine a distance between the headset and the apparatus based on the first time value, the second time value, and information received from the apparatus that is indicative of a third time value associated with the transmission of the second packet and a fourth time value associated with the reception of the third packet, wherein:

the transmitter is further configured to transmit a fourth packet to the apparatus;

the receiver is further configured to receive a fifth packet from the apparatus;

the fifth packet comprises a first symbol sequence for gain control at the headset; and

a gain controller configured to determine a gain level for the reception of the second packet based on the first symbol sequence; and

a transducer configured to provide an audio output based on the determined distance.

36. A watch, comprising:

a transmitter configured to transmit a first packet to an apparatus;

a receiver configured to receive a second packet from the apparatus as a result of the transmission of the first packet, wherein the transmitter is further configured to transmit a third packet to the apparatus a defined period of time after the reception of the second packet;

a ranging controller configured to determine a first time value associated with the reception of the second packet and a second time value associated with the transmission of the third packet, wherein the ranging controller is further configured to determine a distance between the watch and the apparatus based on the first time value, the second time value, and information received from the apparatus that is indicative of a third time value associated with the transmission of the second packet and a fourth time value associated with the reception of the third packet, wherein:

the transmitter is further configured to transmit a fourth packet to the apparatus;

the receiver is further configured to receive a fifth packet from the apparatus;

the fifth packet comprises a first symbol sequence for gain control at the watch; and

a gain controller configured to determine a gain level for the reception of the second packet based on the first symbol sequence; and

a user interface configured to provide an indication based on the determined distance.

37. A sensing device, comprising:

a transmitter configured to transmit a first packet to an apparatus;

a receiver configured to receive a second packet from the apparatus as a result of the transmission of the first packet, wherein the transmitter is further configured to transmit a third packet to the apparatus a defined period of time after the reception of the second packet;

a ranging controller configured to determine a first time value associated with the reception of the second packet and a second time value associated with the transmission of the third packet, wherein the ranging controller is further configured to determine a distance between the sensing device and the apparatus based on the first time value, the second time value, and information received from the apparatus that is indicative of a third time value associated with the transmission of the second packet and a fourth time value associated with the reception of the third packet, wherein:

the transmitter is further configured to transmit a fourth packet to the apparatus;

the receiver is further configured to receive a fifth packet from the apparatus;

the fifth packet comprises a first symbol sequence for gain control at the sensing device; and

a gain controller configured to determine a gain level for the reception of the second packet based on the first symbol sequence; and

a sensor configured to provide data for transmission as a result of the determined distance.