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 method of wireless communication, implemented by a wireless communication receiver, the method comprising:
receiving, over a channel, a wireless signal comprising a data signal portion and a pilot signal portion, wherein the pilot signal portion includes multiple pilot signals multiplexed together in a two-dimensional plane with an x-axis representing delay and a y-axis representing Doppler;
performing, using samples of the wireless signal received within a two-dimensional observation window, a channel estimation, wherein the two-dimensional observation window is configured based on a delay spread and a Doppler spread of the channel; and
recovering, based on the channel estimation, information bits from the wireless signal.
2. The method of claim 1 , wherein the channel estimation is based on an optimization criterion.
3. The method of claim 2 , wherein the optimization criterion comprises a minimum mean square error (MMSE) optimization criterion or is based on a two-dimensional spline function.
4. The method of claim 1 , wherein the multiple pilot signals are multiplexed in the two-dimensional plane based on the delay spread or the Doppler spread of the channel.
5. The method of claim 4 , wherein the multiple pilot signals are multiplexed by sparsely packing the multiple pilot signals in a delay-Doppler torus, and wherein a circumference of the delay-Doppler torus is based on an expected value of the delay spread or an expected value of the Doppler spread.
6. The method of claim 1 , wherein performing the channel estimation comprises:
generating an initial channel estimate based on a subset of the pilot signal portion; and
generating a channel estimate by interpolating and/or predicting the initial channel estimate, wherein the channel estimation is performed using the channel estimate.
7. A wireless communication apparatus comprising a processor, wherein the processor is configured to implement a method of wireless communication, the method comprising:
receiving, over a channel, a wireless signal comprising a data signal portion and a pilot signal portion, wherein the pilot signal portion includes multiple pilot signals multiplexed together in a two-dimensional plane with an x-axis representing delay and a y-axis representing Doppler;
performing, using samples of the wireless signal received within a two-dimensional observation window, a channel estimation, wherein the two-dimensional observation window is configured based on a delay spread and a Doppler spread of the channel; and
recovering, based on the channel estimation, information bits from the wireless signal.
8. The wireless communication apparatus of claim 7 , wherein the channel estimation is based on an optimization criterion.
9. The wireless communication apparatus of claim 8 , wherein the optimization criterion comprises a minimum mean square error (MMSE) optimization criterion or is based on a two-dimensional spline function.
10. The wireless communication apparatus of claim 7 , wherein the multiple pilot signals are multiplexed in the two-dimensional plane based on the delay spread or the Doppler spread of the channel.
11. The wireless communication apparatus of claim 10 , wherein the multiple pilot signals are multiplexed by sparsely packing the multiple pilot signals in a delay-Doppler torus, and wherein a circumference of the delay-Doppler torus is based on an expected value of the delay spread or an expected value of the Doppler spread.
12. The wireless communication apparatus of claim 7 , wherein performing the channel estimation comprises:
generating an initial channel estimate based on a subset of the pilot signal portion; and
generating a channel estimate by interpolating and/or predicting the initial channel estimate, wherein the channel estimation is performed using the channel estimate.
13. The wireless communication apparatus of claim 12 , wherein the interpolating comprises applying a cubic spline interpolator to the initial channel estimate.
14. A non-transitory computer-readable storage medium having code stored thereupon, the code, when executed, causing a processor to implement a method of wireless communication, the non-transitory computer-readable storage medium comprising:
instructions for receiving, over a channel, a wireless signal comprising a data signal portion and a pilot signal portion, wherein the pilot signal portion includes multiple pilot signals multiplexed together in a two-dimensional plane with an x-axis representing delay and a y-axis representing Doppler;
instructions for performing, using samples of the wireless signal received within a two-dimensional observation window, a channel estimation, wherein the two-dimensional observation window is configured based on a delay spread and a Doppler spread of the channel; and
instructions for recovering, based on the channel estimation, information bits from the wireless signal.
15. The non-transitory computer-readable storage medium of claim 14 , wherein the channel estimation is based on an optimization criterion.
16. The non-transitory computer-readable storage medium of claim 15 , wherein the optimization criterion comprises a minimum mean square error (MMSE) optimization criterion or is based on a two-dimensional spline function.
17. The non-transitory computer-readable storage medium of claim 14 , wherein the multiple pilot signals are multiplexed in the two-dimensional plane based on the delay spread or the Doppler spread of the channel.
18. The non-transitory computer-readable storage medium of claim 17 , wherein the multiple pilot signals are multiplexed by sparsely packing the multiple pilot signals in a delay-Doppler torus, and wherein a circumference of the delay-Doppler torus is based on an expected value of the delay spread or an expected value of the Doppler spread.
19. The non-transitory computer-readable storage medium of claim 14 , wherein the instructions for performing the channel estimation comprises:
instructions for generating an initial channel estimate based on a subset of the pilot signal portion; and
instructions for generating a channel estimate by interpolating and/or predicting the initial channel estimate, wherein the channel estimation is performed using the channel estimate.