Methods and apparatus for distributing time, frequency, and/or phase information using NB-IoT
Timing synchronization information is communicated to a plurality of indoor communications devices supporting NB-IoT, e.g., indoor CBSDs supporting NB-IoT, from an outdoor communications device, e.g. a cellular base station supporting NB-IoT signaling using guard bands of a communications channel. An indoor device receiving the timing synchronization information from the outdoor device via NB-IoT signaling may, and sometimes does, process and forward synchronization information to other indoor devices, e.g. other CBSDs, which may be out of direct range of the outdoor device. In some embodiments, a plurality of outdoor base stations supporting NB-IoT receive timing reference information for distribution from the same NPT server coupled to a single reference source, e.g. an atomic clock.
1. A method of communicating timing information, the method comprising:
operating a first indoor device with a Narrowband Internet of Things (NB-IoT) receiver to receive a NB-IoT signal transmitted by a first outdoor base station and to recover timing information from said received NB-IoT signal; and
operating the first indoor device to communicate timing information recovered from said received NB-IoT signal to a second indoor device.
2. The method of claim 1 , wherein recovering timing information includes recovering a first packet of timing synchronization information, said first packet of timing synchronization information including an original reference time stamp indicating a time indicated by a reference timing source which provided timing information to said first outdoor base station.
3. The method of claim 2 , wherein said first packet of timing synchronization information further includes a first stratum indicating the level of proximity to the reference timing source.
4. The method of claim 3 , wherein said first packet of timing synchronization information further includes a first path loss delay offset and a synch counter; and
wherein said first packet of timing synchronization information further includes a reference time stamp indicating a reference time stamp value, frequency information indicating oscillator pulse frequency and phase information indicating oscillator pulse phase.
5. The method of claim 2 , wherein operating the first indoor device to communicate timing information recovered from said NB-IoT signal to a second indoor device includes:
operating the first indoor device to generate a second packet of timing synchronization information from timing information recovered from said first packet of timing synchronization information; and
operating the first indoor device to transmit the second packet of timing synchronization information to the second indoor device.
6. The method of claim 5 , wherein generating the second packet of timing synchronization information includes:
incrementing stratum information to reflect that the second packet of timing synchronization information is being transmitted by a device which is further away from said reference timing source than said first outdoor base station.
7. The method of claim 6 , wherein generating the second packet of timing synchronization information further includes:
including a second path loss delay offset value in said second packet of timing synchronization information, said second path loss delay offset value being larger than a first path loss delay offset value included in said first packet of timing synchronization information.
8. The method of claim 7 , wherein generating the second packet of timing synchronization information further includes:
including a reference time stamp generated by said first indoor device in said second packet of timing synchronization information and an original time stamp obtained from said first packet of timing synchronization information.
9. The method of claim 5 , wherein transmitting the second packet of timing synchronization information to the second indoor device includes transmitting the second packet of timing synchronization information over a wired network interface to said second indoor device.
10. The method of claim 5 , further comprising:
operating the first indoor device to send a synchronization request signal to the first outdoor base station via a wireless NB-IoT signal transmitted by the first indoor device; and
wherein said first packet of timing synchronization information is received from the first outdoor base station in response to said synchronization request signal.
11. The method of claim 10 , further comprising:
storing in a network server or a database coupled to said network server information indicating indoor devices which are to receive timing synchronization signals via NB-IoT signals as part of a NB-IoT timing service; and
operating a network time protocol (NTP) server to provide timing information from said reference timing source to one or more outdoor base stations which provide service to one or more indoor devices which subscribe to a NB-IoT timing service, said one or more outdoor base stations including said first outdoor base station.
12. The method of claim 10 , further comprising:
operating the first outdoor base station to receive timing information from said reference timing source;
operating the first outdoor base station to generate said first packet of timing synchronization information from timing information received from said reference timing source; and
operating the first outdoor base station to transmit said first packet of timing synchronization information to said first indoor base station in response to said synchronization request signal.
13. A communications system comprising:
a first indoor device including:
a first Narrowband Internet of Things (NB-IoT) receiver; and
a first processor; and wherein said first processor is configured to:
operate the first indoor device with the first NB-IoT receiver to receive a NB-IoT signal transmitted by a first outdoor base station and to recover timing information from said received NB-IoT signal; and
operate the first indoor device to communicate timing information recovered from said received NB-IoT signal to a second indoor device.
14. The communications system of claim 13 , wherein said first processor is configured to:
operate the first indoor device to recover a first packet of timing synchronization information, as part of being configured to operate the first indoor device to recover timing information, said first packet of timing synchronization information including an original reference time stamp indicating a time indicated by a reference timing source which provided timing information to said first outdoor base station.
15. The communications system of claim 14 , wherein said first processor is configured to:
generate a second packet of timing synchronization information from timing information recovered from said first packet of timing synchronization information; and
operate the first indoor device to transmit the second packet of timing synchronization information to the second indoor device,
as part of being configured to operate the first indoor device to communicate timing information recovered from said NB-IoT signal to a second indoor device.
16. The communications system of claim 15 , wherein said first processor is configured to:
operate the first indoor device to transmit the second packet of timing synchronization information over a wired network interface to said second indoor device, as part of being configured to operate the first indoor device to transmit the second packet of timing synchronization information to the second indoor device.
17. The communications system of claim 15 , wherein said first processor is further configured to:
operate the first indoor device to send a synchronization request signal to the first outdoor base station via a wireless NB-IoT signal transmitted by the first indoor device; and
wherein said first packet of timing synchronization information is received from the first outdoor base station in response to said synchronization request signal.
18. The communications system of claim 17 , further comprising:
a network server including a second processor; and
wherein said second processor is configured to:
operate the network server to: store in the network server information indicating indoor devices which are to receive timing synchronization signals via NB-IoT signals as part of a NB-IoT timing service or
operate the network server to: retrieve from a database information indicating indoor devices which are to receive timing synchronization signals via NB-IoT signals as part of a NB-IoT timing service; and
a network time protocol (NTP) server including a third processor; and
wherein said third processor is configured to:
operate the network time protocol (NTP) server to provide timing information from said reference timing source to one or more outdoor base stations which provide service to one or more indoor devices which subscribe to a NB-IoT timing service, said one or more outdoor base stations including said first outdoor base station.
19. The communications system of claim 17 , further comprising:
said first outdoor base station including a second processor; and
wherein said second processor is configured to:
operate the first outdoor base station to receive timing information from said reference timing source;
generate said first packet of timing synchronization information from timing information received from said reference timing source; and
operate the first outdoor base station to transmit said first packet of timing synchronization information to said first indoor base station in response to said synchronization request signal.
20. A non-transitory computer readable medium including computer executable instructions which when executed by a processor of a first indoor device cause the first indoor device to perform the steps of:
operating the first indoor device to receive a Narrowband Internet of Things (NB-IoT) signal transmitted by a first outdoor base station and to recover timing information from said received NB-IoT signal; and
operating the first indoor device to communicate timing information recovered from said received NB-IoT signal to a second indoor device.