Method and apparatus for handling communications between spacecraft operating in an orbital environment and terrestrial telecommunications devices that use terrestrial base station communications
A multiple-access transceiver handles communications with mobile stations in environments that exceed mobile station design assumptions without necessarily requiring modifications to the mobile stations. One such environment is in Earth orbit. The multiple-access transceiver is adapted to close communications with mobile stations while exceeding mobile station design assumptions, such as greater distance, greater relative motion and/or other conditions commonly found where functionality of a terrestrial transceiver is to be performed by an orbital transceiver. The orbital transceiver might include a data parser that parses a frame data structure, a signal timing module that adjusts timing based on orbit to terrestrial propagation delays, frequency shifters and a programmable radio capable of communicating from the Earth orbit that uses a multiple-access protocol such that the communication is compatible with, or appears to the terrestrial mobile station to be, communication between a terrestrial cellular base station and the terrestrial mobile station.
1. A method for reconfiguring one or more communication channels of a communication channel allocation scheme of a multiple-access base station, wherein the communication channels are for transmitting one or more signals, wherein the one or more signals are transmitted between the multiple-access base station and terrestrial mobile stations of a plurality of terrestrial mobile stations, the multiple-access base station having one or more transceiver that handles communication with the plurality of terrestrial mobile stations, and wherein the one or more signals are affected by a delay due to an orbital path of the communication channels and/or affected by a Doppler shift due to a motion of an orbital component of the communication channels, the method comprising:
(a) reconfiguring the one or more communication channels of the communication channel allocation scheme into reconfigured communication channels, based at least on the delay and/or the Doppler shift;
(b) reconfiguring a transceiver associated with the one or more communication channels of the communication channel allocation scheme by altering a timeslot synchronization offset associated with a signal transmission timeslot;
(c) updating a configured frequency offset for receiving and transmitting signals of the transceiver associated with the one or more communication channels of the communication channel allocation scheme; and
(d) remapping the reconfigured communication channels in the communication channel allocation scheme.
2. The method of claim 1 , wherein reconfiguring the one or more communication channels is based on a mapping of those terrestrial mobile stations connected to the multiple-access base station.
3. The method of claim 1 , wherein reconfiguring the one or more communication channels is based on a mapping of anticipated terrestrial mobile stations to be connected to the multiple-access base station.
4. The method of claim 1 , wherein reconfiguring the one or more communication channels is based on the multiple-access base station receiving a large number of signals from those terrestrial mobile stations exhibiting similar Doppler shift ranges and operating within similar distances from the multiple-access base station.
5. The method of claim 1 , wherein the multiple-access base station is an orbital base station to be operated in Earth orbit.
6. The method of claim 5 , wherein reconfiguring one or more communication channels of the communication channel allocation scheme and remapping the reconfigured communication channels to blocks of the communication channel allocation scheme are conducted such that a particular communication channel is dedicated to a particular terrestrial mobile station for the entirety of an orbital overpass.
7. The method of claim 1 , further comprising:
wherein the communication channel allocation scheme further comprises a mapping of communication channel blocks;
reconfiguring one or more communication channel blocks of the communication channel allocation scheme by setting a minimum and a maximum timeslot synchronization offset and a minimum and a maximum Doppler compensation for one or more communication channels in the communication channel block, wherein the minimum and the maximum timeslot synchronization offset are based on a minimum and a maximum distance from the multiple-access base station, and wherein the minimum and the maximum Doppler compensations are based on a minimum and a maximum Doppler shift measurement made by the multiple-access base station; and
remapping the communication channel blocks to the communication channel allocation scheme.
8. The method of claim 7 , further comprising before reconfiguring the one or more communication channel blocks of the communication channel allocation scheme, determining, by the multiple-access base station, that one or more communication channel blocks of the mapping of communication channel blocks should be reconfigured.
9. The method of claim 8 , wherein determining that one or more communication channel blocks of the mapping of communication channel blocks should be reconfigured is based on a detection at the multiple-access base station that the plurality of terrestrial mobile stations are densely packed geographically.
10. The method of claim 1 , further comprising:
predicting, by the multiple-access base station, future motion of a footprint of the multiple-access base station using a velocity and a direction of travel of the multiple-access base station;
predicting, by the multiple-access base station, a future Doppler shift and a future distance from the multiple-access base station for one or more terrestrial mobile stations in communication with the multiple-access base station, based at least in part on the future motion of the footprint; and
predicting, using the future Doppler shifts and future distance from the multiple-access base station of the one or more terrestrial mobile stations, that the communication channel allocation scheme of the multiple-access base station will need to be modified in the near future.
11. The method of claim 10 , further comprising reserving one or more communication channels of the communication channel allocation scheme as reserved communication channels that are to be allocated during the predicted future modification of the communication channel allocation scheme, such that communications channels that are actively being used to communicate with terrestrial mobile stations are not abruptly stopped so that the communication channel can be reconfigured.
12. The method of claim 11 , wherein the communication channels of the communication channel allocation scheme are assigned sequential numbers for identification and wherein the reserved communication channels comprise every odd numbered communication channel.
13. A method of processing, on a terrestrial mobile station, a signal from an orbital base station having thereon a multiple-access transceiver configured for communication with a plurality of terrestrial mobile stations, the method comprising:
receiving the signal from the orbital base station to create a received signal, wherein the received signal is consistent with a multiple-access protocol used for communication between a terrestrial cellular base station and the terrestrial mobile station notwithstanding that the orbital base station and the terrestrial mobile station are operating outside of a design assumption of the multiple-access protocol;
parsing the received signal into a frame according to a frame structure assigned to the terrestrial mobile station, wherein the frame structure defines which timeslots are allocated to the terrestrial mobile station, wherein the received signal and allocated timeslots align to account for orbit-terrestrial propagation delays over at least a part of a communication path between the orbital base station and the terrestrial mobile station; and
processing the frame to extract data transmitted by the orbital base station using the multiple-access protocol without accounting for the orbital base station and the terrestrial mobile station are operating outside of the design assumption of the multiple-access protocol.
14. The method of claim 13 , wherein the design assumption of the multiple-access protocol that the orbital base station and the terrestrial mobile station are operating outside of is that the orbital base station and the terrestrial mobile station are separated by more than a maximum communication distance provided for by the multiple-access protocol, and wherein processing the frame to extract the data transmitted by the orbital base station using the multiple-access protocol is done without accounting for the orbital base station and the terrestrial mobile station being separated by more than the maximum communication distance.
15. The method of claim 14 , wherein the frame structure comprises a plurality of slots each having a zero or nonzero timeslot synchronization offset that provides for variable transmission delays that are due to a first communication distance between the orbital base station and the terrestrial mobile station, and timing of transmitted signals relative to the frame structure are signals adjusted for the transmitted signals to the terrestrial mobile station based on the first communication distance where the first communication distance exceeds the maximum communication distance, notwithstanding that the first communication distance exceeds the maximum communication distance.
16. The method of claim 13 , wherein the design assumption of the multiple-access protocol that the orbital base station and the terrestrial mobile station are operating outside of is that the orbital base station and the terrestrial mobile station are moving relative to each other at a velocity that exceeds a maximum velocity provided for by the multiple-access protocol, and wherein processing the frame to extract the data transmitted by the orbital base station using the multiple-access protocol is done without accounting for the orbital base station and the terrestrial mobile station moving relative to each other at the velocity that exceeds the maximum velocity.
17. The method of claim 13 , performed with the terrestrial mobile station comprising one or more of a cellular telephone handset, a smartphone, and/or a connected device.
18. The method of claim 13 , wherein receiving the signal comprises receiving the signal from the orbital base station and processing it as a signal from a terrestrial cellular base station.
19. The method of claim 13 , wherein a separation between the orbital base station and the terrestrial mobile station ranges between 500 to 750 kilometers.
20. The method of claim 13 , further comprising processing the received signal according to a channel assignment assigned to the terrestrial mobile station by the multiple-access transceiver based on a grid location of the terrestrial mobile station on a surface of the Earth relative to the orbital base station and a corresponding Doppler shift.