Method and apparatus for interference cancellation in hybrid satellite-terrestrial network
In a method for cancelling interference caused by a terrestrial transmitter at a satellite receiver in a hybrid satellite-terrestrial network, a satellite receiver generates an interference cancellation signal based on a reference terrestrial signal from the terrestrial transmitter and a received over-the-air (OTA) signal. The satellite receiver then cancels the interference caused by the terrestrial transmitter by combining the interference cancellation signal with the received OTA signal. The interference cancellation signal is a modified version of the reference terrestrial signal.
1. A method for cancelling interference caused by a terrestrial transmitter at a satellite receiver in a hybrid satellite-terrestrial network, the method comprising:
modulating payload data including multimedia content, the payload data being part of satellite information obtained from a satellite signal component of a received over-the-air (OTA) signal;
generating a reference terrestrial signal based on the modulated payload data;
generating, at the satellite receiver, an interference cancellation signal based on the reference terrestrial signal and the received OTA signal, the interference cancellation signal being a modified version of the reference terrestrial signal; and
cancelling, at the satellite receiver, the interference caused by the terrestrial transmitter by combining the interference cancellation signal with the received OTA signal.
2. The method of claim 1 , wherein the generating the interference cancelation signal comprises:
adjusting channel characteristics of the reference terrestrial signal to generate the interference cancellation signal.
3. The method of claim 2 , wherein the channel characteristics include at least one of frequency, timing and amplitude.
4. The method of claim 1 , wherein the reference terrestrial signal is generated by the terrestrial transmitter.
5. The method of claim 1 , wherein the satellite information further includes channel characteristics for the satellite signal component.
6. The method of claim 5 , wherein the channel characteristics include frequency and timing offset information for the satellite signal component.
7. The method of claim 1 , wherein
the satellite information further includes channel characteristics; and the modulating further includes
modulating the payload data including the multimedia content based on the channel characteristics.
8. The method of claim 1 , wherein the generating the interference cancelation signal comprises:
obtaining the satellite information from the satellite signal component of the received OTA signal;
generating a reconstructed satellite digital signal based on the satellite information;
combining the reconstructed satellite digital signal with a digital representation of the received OTA signal to obtain a terrestrial digital signal component of the digital representation of the received OTA signal;
detecting channel characteristics associated with the reference terrestrial signal based on the terrestrial digital signal component and a digital representation of the reference terrestrial signal; and
generating the interference cancellation signal based on the detected channel characteristics.
9. The method of claim 8 , wherein the channel characteristics include at least time delay and frequency offset between transmission and reception of the reference terrestrial signal at the satellite receiver.
10. The method of claim 1 , wherein the interference cancellation signal is a signal that is substantially equal to, but opposite in phase from, the reference terrestrial signal.
11. The method of claim 1 , wherein the satellite signal component of the received OTA signal and the reference terrestrial signal carry the same data.
12. A method for cancelling interference caused by a terrestrial transmitter at a satellite receiver in a hybrid satellite-terrestrial network, the method comprising:
generating, at the satellite receiver, an interference cancellation signal based on a reference terrestrial signal from the terrestrial transmitter and a received over-the-air (OTA) signal, the interference cancellation signal being a modified version of the reference terrestrial signal;
cancelling, at the satellite receiver, the interference caused by the terrestrial transmitter by combining the interference cancellation signal with the received OTA signal;
increasing a transmission power of the reference terrestrial signal;
comparing the transmission power of the reference terrestrial signal with a transmission power level; and
determining whether to transmit the reference terrestrial signal based on the comparing step.
13. The method of claim 12 , wherein the reference terrestrial signal is transmitted if the increased transmission power is less than the transmission power level.
14. A satellite receiver comprising:
an interference cancellation block configured to generate an interference cancellation signal based on a reference terrestrial signal from a terrestrial transmitter and a received over-the-air (OTA) signal, the interference cancelation signal being a modified version of the reference terrestrial signal;
a first combiner configured to combine the interference cancellation signal with the received OTA signal to cancel interference caused by the terrestrial transmitter in a hybrid satellite-terrestrial network; and
a satellite signal decoder configured to obtain satellite information from a satellite signal component of the received OTA signal; wherein
the satellite information is payload data including multimedia content,
the payload data is modulated, and
the reference terrestrial signal is generated based on the modulated payload data.
15. The satellite receiver of claim 14 , wherein the interference cancellation block is configured to adjust channel characteristics of the reference terrestrial signal to generate the interference cancellation signal.
16. The satellite receiver of claim 14 , wherein the reference terrestrial signal is generated by the terrestrial transmitter.
17. The satellite receiver of claim 14 , wherein the satellite information further includes channel characteristics for the satellite signal component.
18. The satellite receiver of claim 14 , wherein
the interference cancellation block includes,
a reconstruction block configured to generate a reconstructed satellite digital signal based on the satellite information,
a second combiner configured to combine the reconstructed satellite digital signal with a digital representation of the received OTA signal to obtain a terrestrial digital signal component of the digital representation of the received OTA signal,
a detector configured to detect channel characteristics associated with the reference terrestrial signal based on the terrestrial digital signal component and a digital representation of the reference terrestrial signal, and
an interference cancellation signal generation block configured to generate the interference cancellation signal based on the detected channel characteristics.
19. An interference cancellation system for a hybrid satellite-terrestrial network, the system comprising:
a terrestrial transmitter configured to compare a transmission power of a reference terrestrial signal with a transmission power level, and to transmit the reference terrestrial signal if the transmission power is less than the transmission power level; and
a satellite receiver including,
an interference cancellation block configured to generate an interference cancellation signal based on the reference terrestrial signal and a received over-the-air (OTA) signal, the interference cancelation signal being a modified version of the reference terrestrial signal, and
a combiner configured to combine the interference cancellation signal with the received OTA signal to cancel interference caused by the terrestrial transmitter in the hybrid satellite-terrestrial network.