Channel acquisition using orthogonal time frequency space modulated pilot signals
Techniques for performing channel estimation in an orthogonal time, frequency and space (OTFS) communication system include receiving a wireless signal comprising a data signal portion and a pilot signal portion in which the pilot signal portion includes multiple pilot signals multiplexed together in the OTFS domain, performing two-dimensional channel estimation in a time-frequency domain based on a minimum mean square error (MMSE) optimization criterion, and recovering information bits using a channel estimate obtained from the two-dimensional channel estimation.
1. A wireless communication method implemented by a transmitter of wireless signals, comprising:
transmitting a wireless signal comprising a data signal portion and a reference signal portion multiplexed in a delay-Doppler domain, wherein the reference signal portion is sent on a first time-frequency lattice that is coarser than a second time-frequency lattice on which data portion is sent, and wherein the first time-frequency lattice is a subset of the second time-frequency lattice.
2. The method of claim 1 , wherein Delay-Doppler (τ,ν) torus associated with the first time-frequency lattice is represented as:
C
τ
P
=
1
/
(
Mdf
)
C
v
P
=
1
/
(
Ndt
)
and wherein a Delay-Doppler torus associate with the second time-frequency lattice is represented as:
C
τ
D
=
1
/
df
C
v
D
=
1
/
dt
where M and N are positive integers, t represents time, and f represents frequency.
3. The method of claim 1 , wherein the first time-frequency lattice forms a sublattice of the second time-frequency lattice.
4. The method of claim 3 , wherein the reference signal portion is generated by packing in the delay-Doppler domain, starting from a finest time-frequency pilot lattice that meets an allowed overhead.
5. The method of claim 3 , wherein the reference signal portion is generated by packing in time-frequency domain, starting from a coarsest time-frequency pilot lattice that supports transmission of at least one reference signal.
6. The method of claim 1 , wherein the first time-frequency lattice is a non-structured subset of the second time-frequency lattice.
7. The method of claim 1 , wherein the wireless signal is transmitted in a downlink direction from a base station to user equipment.
8. The method of claim 1 , wherein the wireless signal is transmitted in an uplink direction from a user equipment to a base station.
9. The method of claim 1 , wherein the wireless signal is transmitted in a time division duplexing (TDD) system.
10. The method of claim 1 , wherein the wireless signal is transmitted in a frequency division duplexing (FDD) system.
11. A transmitter of wireless signals, comprising one or more processors configured to cause the transmitter to implement a method comprising:
transmitting a wireless signal comprising a data signal portion and a reference signal portion multiplexed in a delay-Doppler domain, wherein the reference signal portion is sent on a first time-frequency lattice that is coarser than a second time-frequency lattice on which data portion is sent, and wherein the first time-frequency lattice is a subset of the second time-frequency lattice.
12. The transmitter of claim 11 , wherein Delay-Doppler (τ,ν) torus associated with the first time-frequency lattice is represented as:
C
τ
P
=
1
/
(
Mdf
)
C
v
P
=
1
/
(
Ndt
)
and wherein a Delay-Doppler torus associate with the second time-frequency lattice is represented as:
C
τ
D
=
1
/
df
C
v
D
=
1
/
dt
where M and N are positive integers, t represents time, and f represents frequency.
13. The transmitter of claim 11 , wherein the first time-frequency lattice forms a sublattice of the second time-frequency lattice.
14. The transmitter of claim 13 , wherein the reference signal portion is generated by packing in the delay-Doppler domain, starting from a finest time-frequency pilot lattice that meets an allowed overhead.
15. The transmitter of claim 13 , wherein the reference signal portion is generated by packing in time-frequency domain, starting from a coarsest time-frequency pilot lattice that supports transmission of at least one reference signal.
16. The transmitter of claim 11 , wherein the first time-frequency lattice is a non-structured subset of the second time-frequency lattice.
17. The transmitter of claim 11 , wherein the transmitter is configured to transmit the wireless signal in a downlink direction from a base station to user equipment.
18. The transmitter of claim 11 , wherein the transmitter is configured to transmit the wireless signal is transmitted in an uplink direction from a user equipment to a base station.
19. The transmitter of claim 11 , wherein the transmitter is configured to transmit the wireless signal in a time division duplexing (TDD) system.
20. The transmitter of claim 11 , wherein the transmitter is configured to transmit the wireless signal in a frequency division duplexing (FDD) system.