System and method for communication utilizing time division duplexing
An integrated communication system includes a satellite portion and a terrestrial portion. A plurality of timeslots are allocated for transmission and reception of data by the various components of the satellite portion and terrestrial portion. The allocation of timeslots to the satellite portion and the terrestrial portion may be predetermined or dynamically allocated based on traffic loads, time of day, day of week, and the like. Communication may be accomplished on a single frequency with the appropriate allocation of timeslots. The system includes delay compensation to accommodate signal processing delays and signal propagation delays. For example, a satellite may be instructed to terminate transmission prior to the end of its allocated timeslot to permit the signal from the satellite to propagate to its intended destination within the allocated timeslot to thereby avoid spillover into the next timeslot. This avoids interference between various elements of the communication system.
1. A communication system having a satellite network portion and a terrestrial network portion, the system comprising:
a satellite;
a satellite transmitter configured to transmit data on a selected frequency;
a satellite receiver configured to receive data on the selected frequency;
a satellite timing controller to selectively control operation of the satellite transmitter and the satellite receiver;
a first terrestrial station;
a first terrestrial transmitter configured to transmit data on the selected frequency;
a first terrestrial receiver configured to receive data on the selected frequency; and
a first terrestrial timing controller configured to selectively control operation of the first terrestrial transmitter and the first terrestrial receiver, wherein the satellite timing controller and the first terrestrial timing controller are configured to cooperatively control the respective transmitters and receivers to control transmission and reception of data in selected time intervals such that the satellite transmitter is enabled to transmit data in a first selected time interval, the satellite receiver receives data in a second selected time interval, the first terrestrial transmitter is enabled to transmit data in a third selected time interval, and the first terrestrial receiver receives data in a fourth selected time interval,
wherein the satellite timing controller is configured to initiate transmission from the satellite transmitter prior to the start of the first selected time interval by an amount of time substantially equal to a propagation delay between the satellite and the first terrestrial station.
2. A communication system having a satellite network portion and a terrestrial network portion, the system comprising:
a satellite having a transmitter and receiver configured to communicate on a selected frequency;
a first terrestrial station having a transmitter and receiver configured to communicate on the selected frequency;
a satellite controller to selectively control operation of the satellite transmitter, the satellite controller enabling transmission during a first selected time interval and terminating transmission at a point in time prior to the end of the first selected time interval wherein the point in time prior to the end of the selected time interval is based on a propagation delay between the satellite and the first terrestrial station; and
a first terrestrial controller to selectively control operation of the first terrestrial station transmitter, the first terrestrial controller enabling transmission during a second selected time interval contiguous with the first time interval and terminating transmission at a point in time prior to the end of the second selected time interval wherein the point in time prior to the end of the second selected time interval is based on a propagation delay between the first terrestrial station and the satellite.
3. The system of claim 2 wherein the first terrestrial station is a mobile user terminal having a transmitter and receiver configured to communicate on the selected frequency.
4. The system of claim 3 wherein the user terminal is configured for communication with the satellite only.
5. The system of claim 3 wherein the user terminal is configured for communication with the satellite or with a second terrestrial station.
6. The system of claim 3 , further comprising a system controller configured to determine a propagation delay between the satellite and the first terrestrial station.
7. The system of claim 6 wherein the propagation delay between the satellite and the first terrestrial station is used by the satellite controller to terminate transmission at the point in time prior to the end of the selected time interval.
8. The communication system of claim 2 wherein the first terrestrial controller is further configured to enable transmission at a point in time prior to the second selected time interval.
9. A communication system having a satellite network portion and a terrestrial network portion, the system comprising:
a satellite having a transmitter and receiver configured to transmit and receive data on a selected frequency;
satellite control means for selectively controlling operation of the satellite transmitter and the satellite receiver;
a first terrestrial station having a transmitter and receiver configured to transmit and receive data on the selected frequency;
first terrestrial control means for selectively controlling operation of the first terrestrial transmitter and the first terrestrial receiver, wherein the satellite control means and the first terrestrial control means cooperatively control the respective transmitters and receivers to control transmission and reception of data in selected time intervals such that the satellite transmitter is enabled to transmit data in a first selected time interval, the satellite receiver receives data in a second selected time interval, the first terrestrial transmitter is enabled to transmit data in a third selected time interval, and the first terrestrial receiver receives data in a fourth selected time interval,
wherein the satellite control means comprises means for initiating transmission from the satellite transmitter prior to the start of the first selected time interval by an amount of time substantially equal to a propagation delay between the satellite and the first terrestrial station.