Device, system and global navigation satellite system method using local fine time information
View Patent ↗A user equipment (UE) and method of providing local fine timing assistance are generally described. Prior to storing a Global Navigation Satellite System (GNSS)-cellular time relationship in the UE and, when the network is unable to provide fine timing assistance, a GNSS receiver transmits a request to a modem. The modem, in response, periodically or as scheduled transmits a pulse and pulse timing information (PTI) including a pulse transmission time (PTT) based on cellular network time. The receiver determines a GNSS-cellular time relationship and obtains a GNSS satellite positioning signal and GNSS fix using the PTI. For pulses after the initial pulse, the PTI includes a time difference between the PTT and a PTT of the preceding pulse. The receiver determines a time difference between the PTT and GNSS fix. The modem is configured to terminate pulse transmission in response to receiving a termination request from the receiver.
1. An apparatus of a mobile device comprising:
a processor configured to execute instructions to:
at a first time:
obtain a first Global Navigation Satellite System (GNSS) fix, wherein the first GNSS fix is based on satellite positioning signals received from a plurality of satellites;
determine a first GNSS fix time of the first GNSS fix;
receive, from a cellular modem of the mobile device, a first pulse and first pulse timing information of the first pulse, the first pulse timing information indicating a first pulse time in cellular network time; and
determine, based on the first pulse time in cellular network time and the first GNSS fix time, a GNSS-cellular time relationship; and
at a second time, subsequent to the first time:
determine that a GNSS signal from the plurality of satellites is too weak to extract time of week (TOW) information;
in response to the determination that the GNSS signal from the plurality of satellites is too weak to extract the TOW information, request, from the cellular modem of the mobile device, a second pulse;
receive, from the cellular modem of the mobile device, the second pulse and second pulse timing information of the second pulse, the second pulse timing information indicating a second pulse time in cellular network time, wherein the second pulse timing information is based on:
cumulative cell switching time offsets of inter- and intra-radio access technology (RAT) transitions of the mobile device since an immediately preceding pulse; and
a cumulative number of frame wraparounds for each RAT;
determine, based on the second pulse time and the GNSS-cellular time relationship, a GNSS time; and
obtain, based on the GNSS time and GNSS satellite positioning signals, a second GNSS fix.
2. The apparatus of claim 1 , wherein the processor is further configured to:
start a GNSS timer in response to reception of the second pulse, wherein to determine the GNSS time is further based on the GNSS timer.
3. The apparatus of claim 1 , wherein the processor is further configured to:
determine that the GNSS-cellular time relationship is to be generated; and
in response to the determination that the GNSS-cellular time relationship is desired, request the first pulse from the cellular modern.
4. The apparatus of claim 3 , wherein the processor is further configured to:
in response to the determination that the second GNSS fix is to be generated and the determination that the GNSS signal from the plurality of satellites is too weak to extract the TOW information, request the second pulse from the cellular modem.
5. The apparatus of claim 3 , wherein, to request the first pulse from the cellular modem, the processor is further configured to:
request a plurality of periodic pulses, wherein to request the plurality of periodic pulses includes specifying at least one of a number of the plurality of periodic pulses or a periodicity of transmission of the plurality of periodic pulses.
6. The apparatus of claim 5 , wherein the processor is further configured to:
indicate to the cellular modem to terminate transmission of the plurality of periodic pulses.
7. The apparatus of claim 1 , wherein the first pulse timing information is indicated in the first pulse.
8. The apparatus of claim 1 , wherein the first pulse timing information is indicated in a message separate from the first pulse.
9. A mobile device comprising:
a Global Navigation Satellite System (GNSS) receiver;
a cellular modem; and
a processor configured to execute instructions to:
at a first time:
obtain a first Global Navigation Satellite System (GNSS) fix, wherein the first GNSS fix is based on satellite positioning signals received from a plurality of satellites;
determine a first GNSS fix time of the first GNSS fix;
receive, from a cellular modem of the mobile device, a first pulse and first pulse timing information of the first pulse, the first pulse timing information indicating a first pulse time in cellular network time; and
determine, based on the first pulse time in cellular network time and the first GNSS fix time, a GNSS-cellular time relationship; and
at a second time, subsequent to the first time:
determine that a GNSS signal from the plurality of satellites is too weak to extract time of week (TOW) information;
in response to the determination that the GNSS signal from the plurality of satellites is too weak to extract the TOW information, request, from the cellular modem of the mobile device, a second pulse;
receive, from the cellular modem of the mobile device, the second pulse and second pulse timing information of the second pulse, the second pulse timing information indicating a second pulse time in cellular network time, wherein the second pulse timing information is based on:
cumulative cell switching time offsets of inter- and intra-radio access technology (RAT) transitions of the mobile device since an immediately preceding pulse; and
a cumulative number of frame wraparounds for each RAT;
determine, based on the second pulse time and the GNSS-cellular time relationship, a GNSS time; and
obtain, based on the GNSS time and GNSS satellite positioning signals, a second GNSS fix.
10. The mobile device of claim 9 , wherein the processor is further configured to:
start a GNSS timer in response to reception of the second pulse, wherein to determine the GNSS time is further based on the GNSS timer.
11. The mobile device of claim 9 , wherein the processor is further configured to:
determine that the GNSS-cellular time relationship is to be generated; and
in response to the determination that the GNSS-cellular time relationship is desired, request the first pulse from the cellular modem.
12. The mobile device of claim 11 , wherein the processor is further configured to:
in response to the determination that the second GNSS fix is to be generated and the determination that the GNSS signal from the plurality of satellites is too weak to extract the TOW information, request the second pulse from the cellular modem.
13. The mobile device of claim 11 , wherein, to request the first pulse from the cellular modem, the processor is further configured to:
request a plurality of periodic pulses, wherein to request the plurality of periodic pulses includes specifying at least one of a number of the plurality of periodic pulses or a periodicity of transmission of the plurality of periodic pulses.
14. The mobile device of claim 13 , wherein the processor is further configured to:
indicate to the cellular modem to terminate transmission of the plurality of periodic pulses.
15. The mobile device of claim 9 , wherein the first pulse timing information is indicated in the first pulse.
16. The mobile device of claim 9 , wherein the first pulse timing information is indicated in a message separate from the first pulse.
17. A non-transitory memory medium of a mobile device comprising:
program instructions, the program instructions configured to cause a processor executing the program instructions to:
at a first time:
obtain a first Global Navigation Satellite System (GNSS) fix, wherein the first GNSS fix is based on satellite positioning signals received from a plurality of satellites;
determine a first GNSS fix time of the first GNSS fix;
receive, from a cellular modem of the mobile device, a first pulse and first pulse timing information of the first pulse, the first pulse timing information indicating a first pulse time in cellular network time; and
determine, based on the first pulse time in cellular network time and the first GNSS fix time, a GNSS-cellular time relationship; and
at a second time, subsequent to the first time:
determine that a GNSS signal from the plurality of satellites is too weak to extract time of week (TOW) information;
in response to the determination that the GNSS signal from the plurality of satellites is too weak to extract the TOW information, request, from the cellular modem of the mobile device, a second pulse;
receive, from the cellular modem of the mobile device, the second pulse and second pulse timing information of the second pulse, the second pulse timing information indicating a second pulse time in cellular network time, wherein the second pulse timing information is based on:
cumulative cell switching time offsets of inter- and intra-radio access technology (RAT) transitions of the mobile device since an immediately preceding pulse; and
a cumulative number of frame wraparounds for each RAT;
determine, based on the second pulse time and the GNSS-cellular time relationship, a GNSS time; and
obtain, based on the GNSS time and GNSS satellite position signals, a second GNSS fix.
18. The non-transitory memory medium of claim 17 , wherein the program instructions further cause the processor to:
start a GNSS timer in response to reception of the second pulse, wherein to determine the GNSS time is further based on the GNSS timer.
19. The non-transitory memory medium of claim 17 , wherein the program instructions further cause the processor to:
determine that the GNSS-cellular time relationship is to be generated; and
in response to the determination that the second GNSS fix is to be generated and the determination that the GNSS signal from the plurality of satellites is too weak to extract the TOW information, request the first pulse from the cellular modem.
20. The non-transitory memory medium of claim 19 , wherein, to request the first pulse from the cellular modem, the program instructions further cause the processor to:
request a plurality of periodic pulses, wherein to request the plurality of periodic pulses includes specifying at least one of a number of the plurality of periodic pulses or a periodicity of transmission of the plurality of periodic pulses.
21. The non-transitory memory medium of claim 20 , wherein the program instructions further cause the processor to:
indicate to the cellular modem to terminate transmission of the plurality of periodic pulses.
22. The non-transitory memory medium of claim 17 , wherein the first pulse timing information is indicated in the first pulse.
23. The non-transitory memory medium of claim 17 , wherein the first pulse timing information is indicated in a message separate from the first pulse.
24. A method for operating a mobile device, the method comprising:
at the mobile device:
at a first time:
obtaining a first Global Navigation Satellite System (GNSS) fix, wherein the first GNSS fix is based on satellite positioning signals received from a plurality of satellites;
determining a first GNSS fix time of the first GNSS fix;
receiving; from a cellular modem of the mobile device, a first pulse and first pulse timing information of the first pulse, the first pulse timing information indicating a first pulse time in cellular network time; and
determining, based on the first pulse time cellular network time and the first GNSS fix time, a GNSS-cellular time relationship; and
at a second time, subsequent to the first time:
determining that a GNSS signal from the plurality of satellites is too weak to extract time of week (TOW) information;
in response to the determination that the GNSS signal from the plurality of satellites is too weak to extract the TOW information, requesting, from the cellular modem of the mobile device, a second pulse;
receiving, from the cellular modem of the mobile device, the second pulse and second pulse timing information of the second pulse, the second pulse timing information indicating a second pulse time in cellular network time, wherein the second pulse timing information is based on:
cumulative cell switching time offsets of inter- and intra-radio access technology (RAT) transitions of the mobile device since an immediately preceding pulse; and
a cumulative number of frame wraparounds for each RAT;
determining, based on the second pulse time and the GNSS-cellular time relationship, a GNSS time; and
obtaining, based on the GNSS time and GNSS satellite positioning signals, a second GNSS fix.
25. The method of claim 24 , the method further comprising:
starting a GNSS timer in response to reception of the second pulse, wherein to determine the GNSS time is further based on the GNSS timer.
26. The method of claim 24 , wherein the first pulse is one of a plurality of periodic pulses, the method further comprising:
indicating to the cellular modem to terminate transmission of the plurality of periodic pulses.
27. The method of claim 24 , wherein thy: first pulse timing information is indicated in the first pulse.
28. The method of claim 24 , wherein the first pulse timing information is indicated in a message separate from the first pulse.
29. The apparatus of claim 1 , wherein the second pulse timing information is an absolute reference time (AbsTime) generated by:
AbsTime
=
F
m
+
∑
r
=
1
R
[
dT
r
+
n
r
f
r
+
∑
n
=
1
N
dT
nr
]
.
where:
F m is a current reference time, R is a number of intra-RAT changes, N is a number of inter-RAT changes, n r is a number of frame wraparounds, f r is a time of 1 wraparound, dT nr is a time offset for intra-RAT changes, and dT r is a time offset of inter-RAT changes.