Methods and apparatus for mitigating known interference
Systems and methods for mitigating known interference at a receiving device are provided. A signal from a transmission source is received by a receiving device that is affected by an interference source. At least one of a first pilot signal associated with the transmission source and a second pilot signal associated with the interfering source is determined. The first pilot signal includes information broadcast from the transmission source and the second pilot signal includes information broadcast from the interference source. Interference caused by the interference source is mitigated from the received signal using at least one of the first pilot signal and the second pilot signal.
1. A method for mitigating known interference at a receiving device, the method comprising:
receiving a signal from a transmission source that is affected by an interference source;
determining at least one of i) a first pilot signal associated with the transmission source, and ii) a second pilot signal associated with the interfering source, wherein the first pilot signal includes information broadcast from the transmission source and the second pilot signal includes information broadcast from the interference source; and
mitigating interference caused by the interference source from the received signal using at least one of i) the first pilot signal and ii) the second pilot signal, wherein mitigating the interference caused by the interference source comprises generating an interference whitened received signal based on an interference correlation matrix.
2. The method of claim 1 , wherein the mitigating interference generates an interference mitigated received signal, and wherein the method further comprises processing the interference mitigated received signal to generate at least one of a channel estimate associated with the transmission source, synchronization with the transmission source, decoded data received from the transmission source, and a signal quality indicator for the received signal.
3. The method of claim 1 , wherein the mitigating interference comprises:
computing a channel estimate associated with the interference source based on at least one of the first pilot signal and the second pilot signal; and
applying the channel estimate to the received signal to mitigate the interference.
4. The method of claim 3 , wherein applying the channel estimate comprises combining the channel estimate with the received signal to generate the interference whitened received signal.
5. The method of claim 3 , wherein applying the channel estimate comprises subtracting received interfering signals from the received signal to cancel the interference from the received signal.
6. The method of claim 1 , wherein the mitigating interference comprises generating, independently of an interference mitigated received signal, at least one of a channel estimate associated with the transmission source, synchronization associated with the transmission source, decoded data received from the transmission source, and a signal quality indicator associated with the received signal.
7. The method of claim 1 , wherein the mitigating the interference from the received signal comprises mitigating interference in accordance with:
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where y(i) is the received signal, H 1 (i) is the channel associated with the transmission source, s 1 (i) is a transmitted signal from the transmission source, s 2 (i) is a transmitted signal from the interference source, T is a time/frequency, and i is a time/frequency index.
8. The method of claim 1 , wherein the information broadcast from at least one of the transmission source and the interference source includes at least one of synchronization signals, system information, control information, cell-specific reference signals, Physical Broadcast Channel (PBCH) information, Physical Control Format Indicator Channel information (PCFICH), Physical Downlink Shared Channel information (PDSCH), and Physical Downlink Control Channel information (PDCCH).
9. The method of claim 1 , further comprising:
measuring a quality metric of at least one of the first pilot signal and the second pilot signal; and
determining whether to continue mitigating interference caused by the interference source based on whether the quality metric exceeds a threshold value.
10. The method of claim 1 , wherein determining the second pilot signal comprises at least one of:
scanning neighboring transmission sources to receive the second pilot signal;
receiving assistance data from at least one of the transmission source and the interference source; and
receiving the second pilot signal from the interference source after some other pilot signals become available from the interference source.
11. A system for mitigating known interference at a receiving device, the system comprising:
control circuitry configured to
receive a signal from a transmission source that is affected by an interference source,
determine at least one of i) a first pilot signal associated with the transmission source and ii) a second pilot signal associated with the interfering source, wherein the first pilot signal includes information broadcast from the transmission source and the second pilot signal includes information broadcast from the interference source, and
mitigate interference caused by the interference source from the received signal using at least one of i) the first pilot signal and ii) the second pilot signal, wherein mitigating the interference caused by the interference source comprises generating an interference whitened received signal based on an interference correlation matrix.
12. The system of claim 11 , wherein the control circuitry generates an interference mitigated received signal, and wherein the control circuitry is further configured to process the interference mitigated received signal to generate at least one of a channel estimate associated with the base station, synchronization with the transmission source, decoded data received from the transmission source, and a signal quality indicator for the received signal.
13. The system of claim 11 , wherein the control circuitry is further configured to:
compute a channel estimate associated with the interference source based on at least one of the first pilot signal and the second pilot signal; and
apply the channel estimate to the received signal to mitigate the interference.
14. The system of claim 13 , wherein the control circuitry is further configured to combine the channel estimate with the received signal to generate the interference whitened received signal.
15. The system of claim 13 , wherein the control circuitry is further configured to subtract received interfering signals from the received signal to cancel the interference from the received signal.
16. The system of claim 11 , wherein the control circuitry is further configured to generate, independently of an interference mitigated received signal, at least one of a channel estimate associated with the transmission source, synchronization associated with the transmission source, decoded data received from the transmission source, and a signal quality indicator associated with the received signal.
17. The system of claim 11 , wherein the control circuitry is further configured to mitigate interference in accordance with:
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where y(i) is the received signal, H 1 (i) is the channel associated with the transmission source, s 1 (i) is a transmitted signal from the transmission source, s 2 (i) is a transmitted signal from the interference source, T is a time/frequency, and i is a time/frequency index.
18. The system of claim 11 , wherein the information broadcast from at least one of the transmission source and the interference source includes at least one of synchronization signals, system information, control information, cell-specific reference signals, Physical Broadcast Channel (PBCH) information, Physical Control Format Indicator Channel information (PCFICH), Physical Downlink Shared Channel information (PDSCH), and Physical Downlink Control Channel information (PDCCH).
19. The system of claim 11 , wherein the control circuitry is further configured to:
measure a quality metric of at least one of the first pilot signal and the second pilot signal; and
determine whether to continue mitigating interference caused by the interference source based on whether the quality metric exceeds a threshold value.
20. The system of claim 11 , wherein the control circuitry is further configured to determine the second pilot signal by at least one of:
scanning neighboring transmission sources to receive the second pilot signal;
receiving assistance data from at least one of the transmission source and the interference source; and
receiving the second pilot signal from the interference source after some other pilot signals become available from the interference source.