Apparatus and method for RF interference avoidance in an automotive detection system
A method of mitigates RF interference from an RF interferer. An RF signal is received at an RF transceiver during a time period. The RF signal that includes, for at least a portion of the time period, an interference signal having a cyclic transmission pattern with at least one deterministic feature. The received RF signal is analyzed in order to determine timing information for the at least one deterministic feature and the associated interference signal cyclic transmission pattern. Transmission of the RF signals from the RF transceiver are synchronized with the interference signal transmission pattern based on the determined timing information to mitigate interference between the RF signals and the interference signal.
1. A method of mitigating RF interference from an RF interferer, comprising:
receiving at an RF transceiver during a time period an RF signal that includes, for at least a portion of the time period, an interference signal having a cyclic transmission pattern with at least one deterministic feature, the at least one deterministic feature allowing for the identification of an interfering signal associated with a known interferer;
analyzing the received RF signal to identify the interfering signal and known interferer based on the at least one deterministic feature and determine timing information for the at least one deterministic feature and the associated interference signal cyclic transmission pattern, wherein analyzing the received RF signal comprises:
measuring a power envelope of the received RF signal to identify the at least one deterministic feature and timing information associated therewith, wherein measuring the power envelope comprises application of a sliding power window to the received RF signal, the sliding power window taking a time segment of a set length and viewing total power received during all segments of that length over a time period; and
comparing the identified at least one deterministic feature and timing information associated therewith to one or more known deterministic features associated with RF power envelope transmission patterns to identify a starting time and an ending time for the interference signal cyclic transmission pattern; and
synchronizing transmission of RF signals from the RF transceiver with the interference signal transmission pattern based on the determined timing information to mitigate interference between the RF signals and the interference signal.
2. The method of claim 1 , wherein the interference signal comprises a direct wave from an interferer RF transceiver.
3. The method of claim 2 , wherein the receiving RF transceiver and the interferer RF transceiver transmit in the same frequency band.
4. The method of claim 1 , further comprising accessing the one or more known deterministic features from a library of known transmission patterns for RF interferers.
5. The method of claim 1 , wherein the interference signal transmission pattern includes at least one transition between RF transmission frequencies.
6. The method of claim 1 , wherein receiving the RF signal further comprises scanning on a plurality of RF frequencies at random time intervals.
7. The method of claim 1 , wherein synchronizing comprises temporally alternating the transmission of the RF signals with the determined timing of the cyclic transmission pattern of the interference signal.
8. The method of claim 1 , wherein synchronizing comprises temporally delaying the transmission of the RF signals with respect to the determined timing of the cyclic transmission pattern of the interference signal.
9. The method of claim 1 , wherein synchronizing comprises adjusting the transmission frequency of the RF signals based on at least one maximum collision point between the interference signal and previously transmitted RF signals.
10. The method of claim 1 , wherein synchronizing comprises temporally adjusting the transmission of the RF signals to transmit only when noise from the interfering signal is below a maximum noise threshold.
11. The method of claim 1 further comprising adjusting the transmitted RF signals to have a cyclic transmission pattern that matches the cyclic transmission pattern of the interference signal.
12. The method of claim 1 , wherein synchronizing comprises modifying the transmission pattern of the RF signals and aligning the transmission timing of the modified RF signals with the determined timing of the cyclic transmission pattern of the interference signal.
13. The method of claim 1 , wherein the at least one deterministic feature occurs at a known temporal offset from the start and end of a known cyclic transmission pattern.
14. The method of claim 1 , wherein the at least one deterministic feature comprises a power amplitude characteristic selected from: a slope value; a geometric shape; volume; height; and a higher order derivative value.
15. An RF transceiver configured to mitigate RF interference from an interference signal, comprising:
an RF receiving module configured to receive, during a time period, an RF signal that includes for at least a portion of the time period an interference signal having a periodic cyclic transmission pattern with at least one deterministic feature, the at least one deterministic feature allowing for the identification of an interfering signal associated with a known interferer;
an interference detector configured to analyze the received RF signal to identify the interfering signal and known interferer based on the at least one deterministic feature and determine timing information for the at least one deterministic feature and the associated interference signal cyclic transmission pattern, wherein the interference detector includes a controller configured to analyze the received RF signal by:
measuring a power envelope of the received RF signal to identify the at least one deterministic feature and timing information associated therewith, wherein measuring the power envelope comprises application of a sliding power window to the received RF signal, the sliding power window taking a time segment of a set length and viewing total power received during all segments of that length over a time period; and
comparing the identified at least one deterministic feature and timing information associated therewith to one or more known deterministic features associated with RF power envelope transmission patterns to identify a starting time and an ending time for the interference signal cyclic transmission pattern; and
an RF transmitter configured to synchronize transmission of RF signals with the interference signal cyclic transmission pattern based on the timing information to mitigate interference between the RF signals and the interference signal.
16. The RF transceiver of claim 15 , wherein the RF transceiver comprises an automotive radar transceiver.
17. The RF transceiver of claim 15 , wherein the controller is further configured to access, from a library contained within memory, data related to the one or more known transmission patterns for detection systems such that the known transmission patterns can be compared to the received RF signal to identify the interferer based on the one or more deterministic features.
18. The RF transceiver of claim 15 , wherein the RF receiving module receives the RF signal by scanning on a plurality of RF frequencies at random time intervals.
19. The RF transceiver of claim 15 , wherein the controller is configured to synchronize the transmission of the RF signals by one of:
temporally alternating the transmission of the RF signals with the determined timing of the cyclic transmission pattern of the interference signal;
temporally delaying the transmission of the RF signals with respect to the determined timing of the cyclic transmission pattern of the interference signal; and
modifying the transmission pattern of the RF signals and aligning the transmission timing of the modified RF signals with the determined timing of the cyclic transmission pattern of the interference signal.
20. The RF transceiver of claim 15 , wherein the at least one deterministic feature occurs at a known temporal offset from the start and end of a known cyclic transmission pattern.