Method and apparatus for timing advance estimation

1. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform at least the following:

determine a first timing associated with a first signal, wherein the first signal corresponds to a cellular downlink signal transmitted by a cellular base station;

detect a second timing associated with a second signal, wherein the second signal corresponds to a cellular uplink signal transmitted by a cellular device, wherein the first signal is a signal different from the second signal;

estimate a timing advance value based at least in part on the detected first timing and the second timing, wherein the timing advance value is estimated by subtracting a time difference between the first timing and the second timing from a guard period, the timing advance value corresponds to a difference between a start timing of a first uplink pilot time slot a id a second unlink pilot time slot, and the second uplink pilot time slot is the earliest arrived uplink pilot time slot field; and

synchronize to a surrounding cellular user by transmitting signals using the estimated timing advance value.

2. The apparatus according to claim 1 , wherein the apparatus is caused to further perform:

determine a time difference between the first timing and the second timing, wherein the timing advance value is estimated based at least in part on the determined time difference.

3. The apparatus according to claim 1 , wherein the apparatus is caused to further perform:

detect a common downlink signal to obtain frame timing, wherein the first timing is determined at least in part based on the obtained frame timing.

4. The apparatus according to claim 1 , wherein the first signal comprises a downlink signal or an uplink signal and the second signal comprises an uplink signal.

5. The apparatus according to claim 1 , wherein the first signal comprises a downlink pilot time slot, and the second signal comprises an uplink pilot time slot.

6. The apparatus according to claim 1 , wherein the second timing associates with at least one of the start and the end of the second signal.

7. The apparatus according to claim 1 , wherein the estimated timing advance value associates with a cellular user that is synchronized with a cellular base station.

8. The apparatus according to claim 1 , wherein the apparatus is caused to further perform:

receive system information from a remote node; and

determine the position of the first signal and the second signal within a frame based on the received system information,

wherein the system information comprises at least one of a preamble format configuration of a physical random access channel, and a resource allocation of the physical random access channel and,

wherein the physical random access channel transmission is filtered out of the first signal and the second signal with the remainder of the first and the second signal being configured for the timing advance estimation.

9. The apparatus according to claim 1 , wherein the first timing associates with the end of the first signal.

10. A method, comprising:

determining a first timing associated with a first signal, wherein the first signal corresponds to a cellular downlink signal transmitted by a cellular base station;

detecting a second timing associated with a second signal, wherein the second signal corresponds to a cellular uplink signal transmitted by a cellular device, wherein the first signal is a signal different from the second signal;

estimating a timing advance value based at least in part on the detected first timing and the second timing, wherein the timing advance value is estimated by subtracting a time difference between the first timing and the second timing from a guard period, the timing advance value corresponds to a difference between a timing of a first uplink pilot time slot and a second uplink pilot time slot, and the second uplink pilot time slot is the earliest arrived uplink pilot time slot field; and

synchronizing to a surrounding cellular user by transmitting signals using the estimated timing advance value.

11. The method according to claim 10 , wherein the estimating the timing advance value further comprises determining a time difference between the first timing and the second timing, wherein the timing advance value is estimated based at least in part on the determined time difference.

12. The method according to claim 10 , wherein the determining the first timing further comprises detecting a common downlink signal to obtain frame timing.

13. The method according to claim 10 , wherein the first signal comprises a downlink signal or an uplink signal and the second signal comprises an uplink signal.

14. The method according to claim 10 , wherein the first signal comprises a downlink pilot time slot, the second signal comprises an uplink pilot time slot.

15. The method according to claim 10 , further comprising:

transmitting signals with a timing associated with the estimated timing advance value.

16. The method according to claim 10 , wherein the method further comprises:

receiving system information from a remote node; and

determining the position of the first signal and the second signal within a frame based on the received system information,

wherein the system information comprises at least one of a preamble format configuration of a physical random access channel, and a resource allocation of the physical random access channel and,

wherein the physical random access channel transmission is filtered out of the first signal and the second signal with the remainder of the first and the second signal being configured for the timing advance estimation.

17. A computer program product comprising a non-transitory computer-readable medium bearing computer program code embodied therein for use with a computer, the computer program code comprising:

code for determining a first timing associated with a first signal, wherein the first signal corresponds to a cellular downlink signal transmitted by a cellular base station;

code for detecting a second timing associated with a second signal, wherein the second signal corresponds to a cellular uplink signal transmitted by a cellular device, wherein the first signal is a signal different from the second signal;

code for estimating a timing advance value based at least in part on the detected first timing and the second timing, wherein the timing advance value is estimated by subtracting a time difference between the first timing and the second timing from a guard period, the timing advance value corresponds to a difference between a start timing of a first uplink pilot time slot and a second uplink pilot time slot, and the second uplink pilot time slot is the earliest arrived uplink pilot time slot field; and

code for synchronizing to a surrounding cellular user by transmitting signals using the estimated timing advance value.

18. The computer program product according to claim 17 , further comprising

code for transmitting signals with a timing associated with the estimated timing advance value.

19. The computer program product according to claim 17 , further comprising:

code for receiving system information from a remote node; and

code for determining the position of the first signal and the second signal within a frame based on the received system information,

wherein the system information comprises at least one of a preamble format configuration of a physical random access channel, and a resource allocation of the physical random access channel and,

wherein the physical random access channel transmission is filtered out of the first signal and the second signal with the remainder of the first and the second signal being configured for the timing advance estimation.