Ultra wide band signals using orthogonal time frequency space modulation
Methods, systems and devices for wireless communication are described. One example method includes mapping information bits to transmission resources in a two-dimensional delay-Doppler grid In this example, the two-dimensional delay-Doppler grid includes N Doppler elements along a Doppler dimension and M delay elements along a delay dimension, and N and M are positive integers. The example method continues with converting a result of the mapping to a signal waveform, and generating an orthogonal time frequency space (OTFS) waveform by spreading the signal waveform using a spreading scheme. In some examples, the signal waveform includes an ultra-wide band (UWB) waveform.
1. A method of wireless communication, comprising:
mapping information bits to transmission resources in a two-dimensional delay-Doppler grid, wherein the two-dimensional delay-Doppler grid comprises N Doppler elements and M delay elements, where N and M are positive integers;
converting a result of the mapping to an orthogonal time frequency space (OTFS) waveform comprising sequences of pulses;
mapping the sequences of pulses to predetermined frequency bands and summing frequency-mapped signals to generate a resulting signal; and
generating an ultra-wideband (UWB) signal by spreading the resulting signal over a bandwidth greater than 200 MHz using a spreading scheme.
2. The method of claim 1 , wherein the sequences of pulses are modulated using a complex waveform depending on a coordinate of a Doppler element of a corresponding pulse.
3. The method of claim 2 , wherein time-domain positions of pulses in the sequences of pulses are shifted along a time dimension depending on a coordinate of a delay element of the corresponding pulse.
4. The method of claim 2 , wherein the sequences of pulses are mapped to overlapping frequency bands in the OTFS waveform.
5. The method of claim 1 , wherein the OTFS waveform corresponds to an output of exciting a two-dimensional filter in a delay-Doppler domain using the transmission resources.
6. The method of claim 1 , wherein the spreading scheme comprises applying a chirp spread spectrum scheme, applying a chaos-based transformation, applying a pseudo noise modulation, or applying frequency hopping.
7. The method of claim 1 , wherein the mapping the information bits to the two-dimensional delay-Doppler grid comprises multiplexing user data for multiple users and mapping to the two-dimensional delay-Doppler grid.
8. The method of claim 7 , wherein the multiplexing is performed along a delay dimension, a Doppler dimension, or a spatial dimension.
9. The method of claim 7 , wherein the multiplexing is performed using code division multiplexing.
10. The method of claim 1 , wherein the converting the result of the mapping to the OTFS waveform comprises applying a Symplectic Fast Fourier Transform (SFFT).
11. The method of claim 1 , wherein the converting the result of the mapping to the OTFS waveform comprises applying a Zak transform over a Doppler dimension.
12. An apparatus for wireless communication, comprising a processor configured to implement a method comprising:
mapping information bits to transmission resources in a two-dimensional delay-Doppler grid, wherein the two-dimensional delay-Doppler grid comprises N Doppler elements and M delay elements, where N and M are positive integers;
converting a result of the mapping to an orthogonal time frequency space (OTFS) waveform comprising sequences of pulses;
mapping the sequences of pulses to predetermined frequency bands and summing frequency-mapped signals to generate a resulting signal; and
generating an ultra-wideband (UWB) signal by spreading the resulting signal over a bandwidth greater than 200 MHz using a spreading scheme.
13. The apparatus of claim 12 , wherein the sequences of pulses are modulated using a complex waveform depending on a coordinate of a Doppler element of a corresponding pulse.
14. The apparatus of claim 13 , wherein time-domain positions of pulses in the sequences of pulses are shifted along a time dimension depending on a coordinate of a delay element of the corresponding pulse.
15. The apparatus of claim 13 , wherein the sequences of pulses are mapped to overlapping frequency bands in the OTFS waveform.
16. The apparatus of claim 12 , wherein the OTFS waveform corresponds to an output of exciting a two-dimensional filter in a delay-Doppler domain using the transmission resources.
17. The apparatus of claim 12 , wherein the spreading scheme comprises applying a chirp spread spectrum scheme, applying a chaos-based transformation, applying a pseudo noise modulation, or applying frequency hopping.
18. The apparatus of claim 12 , wherein the mapping the information bits to the two-dimensional delay-Doppler grid comprises multiplexing user data for multiple users and mapping to the two-dimensional delay-Doppler grid.
19. The apparatus of claim 18 , wherein the multiplexing is performed along a delay dimension, a Doppler dimension, or a spatial dimension.
20. The apparatus of claim 18 , wherein the multiplexing is performed using code division multiplexing.
21. The apparatus of claim 12 , wherein the converting the result of the mapping to the OTFS waveform comprises applying a Symplectic Fast Fourier Transform (SFFT).