Adaptive transmission and interference cancellation for MIMO radar

• US 9,689,967 B1
• Filed: 04/07/2017
• Issued: 06/27/2017
• Est. Priority Date: 04/07/2016
• Status: Active Grant

• Current Assignee: Uhnder, Inc.
• Original Assignee: Uhnder, Inc.
• Inventors: Stark, Wayne E., Davis, Curtis, Bordes, Jean P., Rao, Raghunath K., Maher, Monier, Schmid, Otto A., Hegde, Manju
• Primary Examiner(s): Bythrow, Peter
• Application Number:
  US15/481,648
• Time in Patent Office: 81 Days
• Field of Search: 342 70, 342159
• CPC Class Codes: G01S 13/87 Combinations of radar systems, e.g. primary radar and secondary radar
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 13/93 for anti-collision purposes
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/9316 combined with communication equipment with other vehicles or with base stations
• CPC Class Codes: G01S 2013/9322 using additional data, e.g. driver condition, road state or weather data
• CPC Class Codes: G01S 2013/93271 in the front of the vehicles
• CPC Class Codes: G01S 2013/93272 in the back of the vehicles
• CPC Class Codes: G01S 7/023 Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36
• CPC Class Codes: G01S 7/0233 Avoidance by phase multiplex
• CPC Class Codes: G01S 7/0234 Avoidance by code multiplex
• CPC Class Codes: G01S 7/292 Extracting wanted echo-signals
• CPC Class Codes: G01S 7/4021 of receivers
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04L 27/2278 using correlation techniques, e.g. for spread spectrum signals

Abstract

A radar system has different modes of operation. In one mode the radar operates as a single-input, multiple-output (SIMO) radar system utilizing one transmitted signal from one antenna at a time. Codes with known excellent autocorrelation properties are utilized in this mode. At each receiver the response after correlating with various possible transmitted signals is measured in order to estimate the interference that each transmitter will represent at each receiver. The estimated effect of the interference from one transmitter on a receiver that correlates with a different code is used to mitigate the interference. In another mode, the radar operates as a MIMO radar system utilizing all the antennas at a time. Interference cancellation of the non-ideal cross correlation sidelobes when transmitting in the MIMO mode are employed to remove ghost targets due to unwanted sidelobes.

Claims

1. A method for measuring interference in a radar system in a vehicle, the method comprising:

providing a radar system comprising a plurality of transmitters configured for installation and use on a vehicle and configured to transmit radio signals, and a plurality of receivers configured for installation and use on the vehicle and configured to receive radio signals that include the transmitted radio signals reflected from objects in the environment;

wherein each transmitter of the plurality of transmitters is further configured to phase modulate the transmitted radio signals using a unique spreading code;

for a first period of time, transmitting with only a first transmitter of the plurality of transmitters and receiving radio signals transmitted from the first transmitter with each receiver of the plurality of receivers;

correlating the received radio signals with each receiver of the plurality of receivers to estimate interference that the first transmitter will represent at each receiver of the plurality of receivers;

for a second period of time, transmitting with only a second transmitter of the plurality of transmitters and receiving radio signals transmitted from the second transmitter with each receiver of the plurality of receivers;

correlating the received radio signals with each receiver of the plurality of receivers to estimate interference that the second transmitter will represent at each receiver of the plurality of receivers; and

mitigating at each receiver of the plurality of receivers the estimated interference that is due to interfering radio signals transmitted by the first and second transmitters of the plurality of transmitters.

2. The method of claim 1, wherein transmitting with a first transmitter comprises further modulating the transmitted radio signals with spreading codes selected with known autocorrelation properties.

3. The method of claim 2, wherein the estimated effect of the interference from a particular transmitter on a receiver that correlates with a different set of spreading codes is used to mitigate the interference from the particular transmitter.

4. The method of claim 2, wherein a length of the spreading codes is selected based upon an interference level.

5. The method of claim 2, wherein the spreading codes are binary codes, and comprise one of m-sequences, APAS sequences, Golay sequences, Frank-Zadoff-Chu sequences, and Hadamard codes.

6. The method of claim 1, wherein transmitting with a first transmitter comprises the first transmitter transmitting with a single antenna.

7. The method of claim 6, wherein transmitting with a second transmitter comprises the second transmitter transmitting with a different single antenna.

8. A radar sensing system for a vehicle, the radar sensing system comprising:

a plurality of transmitters configured for installation and use on a vehicle, and further configured to transmit radio signals, wherein each transmitter of the plurality of transmitters is further configured to phase modulate the transmitted radio signals using a unique spreading code;

a plurality of receivers configured for installation and use on the vehicle, and further configured to receive radio signals that include the transmitted radio signals reflected from objects in the environment; and

a controller configured to direct during a first operational mode, for a first period of time, only a first transmitter of the plurality of transmitters to transmit, and wherein radio signals transmitted from just the first transmitter are received by each receiver of the plurality of receivers;

wherein, during the first operational mode, each receiver of the plurality of receivers is configured to correlate the received radio signals to estimate interference that the first transmitter will represent at each receiver of the plurality of receivers;

wherein the controller is further configured to direct during the first operational mode, for a second period of time, only a second transmitter of the plurality of transmitters to transmit, wherein radio signals transmitted from just the second transmitter are received by each receiver of the plurality of receivers;

wherein, during the first operational mode, each receiver of the plurality of receivers is further configured to correlate the received radio signals to estimate interference that the second transmitter will represent at each receiver of the plurality of receivers; and

wherein during a second operation mode, each receiver of the plurality of receivers is further configured to mitigate the estimated interference that is due to interfering radio signals transmitted by the first and second transmitters of the plurality of transmitters.

9. The radar sensing system of claim 8, wherein, during the first operational mode, each transmitter of the plurality of transmitters is further configured to further modulate the transmitted radio signals using spreading codes selected with known autocorrelation properties, and wherein each receiver of the plurality of receivers correlates with a different set of spreading codes.

10. The radar sensing system of claim 9, wherein the second transmitter transmits a radio signal via a second antenna.

11. The radar sensing system of claim 9, wherein each receiver of the plurality of receivers is configured to estimate the effect of interference from each transmitter that correlates with a different set of spreading codes, and wherein the estimated interference is used to mitigate the interference.

12. The radar sensing system of claim 9, wherein a length of the spreading codes is selected based upon an interference level.

13. The radar sensing system of claim 9, wherein the spreading codes are binary codes, and comprise one of m-sequences, APAS sequences, Golay sequences, Frank-Zadoff-Chu sequences, and Hadamard codes.

14. The radar sensing system of claim 8, wherein the first transmitter transmits a radio signal via a first antenna.

15. A method for measuring interference in a radar system in a vehicle, the method comprising:

providing a radar sensing system comprising at least two transmitters configured for installation and use on a vehicle and configured to transmit radio signals, and at least two receivers configured for installation and use on the vehicle and configured to receive radio signals that include the transmitted radio signals reflected from objects in the environment;

wherein each transmitter of the at least two transmitters is further configured to phase modulate the transmitted radio signals using a unique spreading code;

in a first mode of operation, exclusively transmitting in turn each transmitter of the at least two transmitters for a separate period of time and receiving radio signals transmitted from each respective transmitter of the at least two transmitters with the at least two receivers, and wherein the radio signals are received from only one transmitter at a time;

in the first mode of operation, with each receiver of the at least two receivers, correlating the received radio signals to estimate interference due to particular transmitters at each receiver of the at least two receivers; and

in a second mode of operation, mitigating at each receiver of the at least two receivers the estimated interference that is due to interfering radio signals transmitted by other transmitters of the at least two transmitters.

16. The method of claim 15, wherein exclusively transmitting in turn each transmitter comprises further modulating the transmitted radio signals with spreading codes selected with known autocorrelation properties.

17. The method of claim 16, wherein the estimated effect of the interference from a particular transmitter on a receiver that correlates with a different set of spreading codes is used to mitigate the interference from the particular transmitter.

18. The method of claim 16, wherein a length of the spreading codes is selected based upon an interference level.

19. The method of claim 16, wherein the spreading codes are binary codes, and comprise one of m-sequences, APAS sequences, Golay sequences, Frank-Zadoff-Chu sequences, and Hadamard codes.

20. The method of claim 15, wherein each transmitter of the at least two transmitters is coupled with a separate antenna.