Radar coordination for multi-radar coexistence
Disclosed are techniques for transmitting and receiving a plurality of encoded information bits on a radar signal. In an aspect, a transmitter radar generates a first set of modulated phase-coded symbols to convey the plurality of encoded information bits, generates a second set of modulated phase-coded symbols as reference symbols having a known phase modulation, phase codes a plurality of chirps of the radar signal according to the first and second sets of modulated phase-coded symbols, and transmits the plurality of chirps according to the phase coding. A receiver radar determines a phase difference between the receiver and transmitter radars based on a phase of the plurality of chirps, equalizes the phase based on the determined phase difference, determines a phase code of the first set of symbols based on the equalized phase, and decodes the encoded information bits based on the phase code of the first set of symbols.
1. An apparatus, comprising:
a receiver radar configured to:
receive, from a transmitter radar, a plurality of chirps of a radar signal, wherein the plurality of chirps of the radar signal are phase coded according to a first set of phase-shift keying (PSK) modulated phase-coded symbols and a second set of PSK modulated phase-coded symbols, wherein the first set of PSK modulated phase-coded symbols convey a plurality of encoded information bits, and wherein the second set of PSK modulated phase-coded symbols are reference symbols having a known phase modulation;
determine a phase difference between the receiver radar and the transmitter radar based on a phase of the plurality of chirps of the radar signal phase coded according to the second set of PSK modulated phase-coded symbols;
equalize the phase of the plurality of chirps of the radar signal based on the determined phase difference;
determine a phase code of the first set of PSK modulated phase-coded symbols based on the equalized phase of the plurality of chirps; and
decode the plurality of encoded information bits based on the phase code of the first set of PSK modulated phase-coded symbols.
2. The apparatus of claim 1 , wherein a number of PSK modulated phase-coded symbols in the first set is equal to a number of the plurality of chirps of the radar signal minus a number of PSK modulated phase-coded symbols in the second set.
3. The apparatus of claim 1 , wherein a number of the plurality of encoded information bits is represented as (Nc−Nc1)*Q, wherein Nc is a number of the plurality of chirps of the radar signal, Nc1 is a number of PSK modulated phase-coded symbols in the second set, and Q is a PSK modulation order.
4. The apparatus of claim 1 , wherein:
a first set of chirps in the plurality of chirps of the radar signal are phase coded according to the first set of PSK modulated phase-coded symbols; and
a second set of chirps in the plurality of chirps of the radar signal are phase coded according to the second set of PSK modulated phase-coded symbols.
5. The apparatus of claim 4 , wherein the first set of chirps in the plurality of chirps of the radar signal are interleaved with the second set of chirps in the plurality of chirps of the radar signal.
6. The apparatus of claim 4 , wherein the first set of chirps in the plurality of chirps of the radar signal are phase coded according to s k exp(jØ m (2) −Ø m (1) ), where s k is a k-th symbol of the first set of PSK modulated phase-coded symbols to be modulated to a m-th chirp of the plurality of chirps, j represents the square root of −1, Ø m (2) ) is phase noise of the m-th chirp at the receiver radar, and Ø m (1) is phase noise of the m-th chirp at the transmitter radar.
7. The apparatus of claim 4 , wherein the second set of chirps in the plurality of chirps of the radar signal are phase coded according to d k exp(jØ m (2) −Ø m (1) ), where d k is a k-th symbol of the second set of PSK modulated phase-coded symbols to be modulated to a m-th chirp of the plurality of chirps, j represents the square root of −1, Ø m (2) is phase noise of the m-th chirp at the receiver radar, and Ø m (1) is phase noise of the m-th chirp at the transmitter radar.
8. The apparatus of claim 1 , wherein the radar signal is received from a radar of an autonomous or semi-autonomous vehicle.
9. The apparatus of claim 8 , wherein the plurality of encoded information bits comprises an identifier of the autonomous or semi-autonomous vehicle.
10. The apparatus of claim 9 , wherein the identifier comprises a license plate number of the autonomous or semi-autonomous vehicle, a vehicle identification number (VIN) of the autonomous or semi-autonomous vehicle, or a user equipment (UE) identifier associated with the autonomous or semi-autonomous vehicle.
11. The apparatus of claim 9 , further comprising:
a transceiver configured to establish a sidelink with the autonomous or semi-autonomous vehicle based on the identifier to coordinate radar transmissions between the autonomous or semi-autonomous vehicle and the receiver radar.
12. The apparatus of claim 1 , wherein the receiver radar comprises a radar of an autonomous or semi-autonomous vehicle.
13. The apparatus of claim 1 , wherein the receiver radar is further configured to:
determine a Doppler of the first set of PSK modulated phase-coded symbols based on the equalized phase of the plurality of chirps of the radar signal.
14. A method of receiving a plurality of encoded information bits on a radar signal performed by a receiver radar, comprising:
receiving, from a transmitter radar, a plurality of chirps of the radar signal, wherein the plurality of chirps of the radar signal are phase coded according to a first set of phase-shift keying (PSK) modulated phase-coded symbols and a second set of PSK modulated phase-coded symbols, wherein the first set of PSK modulated phase-coded symbols convey the plurality of encoded information bits, and wherein the second set of PSK modulated phase-coded symbols are reference symbols having a known phase modulation;
determining a phase difference between the receiver radar and the transmitter radar based on a phase of the plurality of chirps of the radar signal phase coded according to the second set of PSK modulated phase-coded symbols;
equalizing the phase of the plurality of chirps of the radar signal based on the determined phase difference;
determining a phase code of the first set of PSK modulated phase-coded symbols based on the equalized phase of the plurality of chirps; and
decoding the plurality of encoded information bits based on the phase code of the first set of PSK modulated phase-coded symbols.
15. The method of claim 14 , wherein a number of the plurality of encoded information bits is represented as (Nc−Nc1)*Q, wherein Nc is a number of the plurality of chirps of the radar signal, Nc1 is a number of PSK modulated phase-coded symbols in the second set, and Q is a PSK modulation order.
16. The method of claim 14 , wherein:
a first set of chirps in the plurality of chirps of the radar signal are phase coded according to the first set of PSK modulated phase-coded symbols; and
a second set of chirps in the plurality of chirps of the radar signal are phase coded according to the second set of PSK modulated phase-coded symbols.
17. The method of claim 16 , wherein the first set of chirps in the plurality of chirps of the radar signal are interleaved with the second set of chirps in the plurality of chirps of the radar signal.
18. The method of claim 16 , wherein the first set of chirps in the plurality of chirps of the radar signal are phase coded according to s_k exp([(jØ)]_m{circumflex over ( )}((2))-Ø_m{circumflex over ( )}((1))), where sk is a k-th symbol of the first set of PSK modulated phase-coded symbols to be modulated to a m-th chirp of the plurality of chirps, j represents the square root of −1, Ø_m{circumflex over ( )}((2)) is phase noise of the m-th chirp at the receiver radar, and 0_m{circumflex over ( )}((1)) is phase noise of the m-th chirp at the transmitter radar.
19. The method of claim 16 , wherein the second set of chirps in the plurality of chirps of the radar signal are phase coded according to d_k exp([(jØ)]_m{circumflex over ( )}((2))-Ø_m{circumflex over ( )}((1))), where dk is a k-th symbol of the second set of PSK modulated phase-coded symbols to be modulated to a m-th chirp of the plurality of chirps, j represents the square root of −1, Ø_m{circumflex over ( )}((2)) is phase noise of the m-th chirp at the receiver radar, and Ø_m{circumflex over ( )}((1)) is phase noise of the m-th chirp at the transmitter radar.