Orthogonal time frequency space modulation techniques
Orthogonal Time Frequency Space (OTFS) is a novel modulation scheme with significant benefits for 5G systems. The fundamental theory behind OTFS is presented in this paper as well as its benefits. We start with a mathematical description of the doubly fading delay-Doppler channel and develop a modulation that is tailored to this channel. We model the time varying delay-Doppler channel in the time-frequency domain and derive a new domain (the OTFS domain) where we show that the channel is transformed to a time invariant one and all symbols see the same SNR. We explore aspects of the modulation like delay and Doppler resolution, and address design and implementation issues like multiplexing multiple users and evaluating complexity. Finally we present some performance results where we demonstrate the superiority of OTFS.
1. A wireless communication method, comprising:
receiving information bits;
generating information symbols from the information bits; and
generating a transmission burst from the information symbols such that the generating the transmission burst corresponds to:
mapping the information symbols to a two dimensional delay-Doppler plane;
applying a first transform to the mapped information symbols in the two dimensional delay-Doppler plane to mapped information symbols in a time frequency plane;
transforming the mapped information symbols in the time frequency plane using a second transform to the transmission burst in a time domain using a generalized modulation scheme.
2. The method of claim 1 , wherein the mapping the information symbols to the two dimensional delay-Doppler plane includes mapping the information symbols along points of a lattice in the two dimensional delay-Doppler plane, wherein the points are separated by a reciprocal of maximum delay along a delay dimension and a reciprocal of a maximum Doppler shift along a Doppler dimension.
3. The method of claim 2 , wherein, during the first transformation, one or more pilot symbols are mapped to at least some of the points of the lattice in the two dimensional delay-Doppler plane.
4. The method of claim 1 , wherein the generating the information symbols includes using at least one of a quadrature amplitude modulation (QAM) and a quadrature phase shift keying (QPSK) modulation.
5. The method of claim 1 , wherein the transmission burst is transmitted using an orthogonal frequency division multiplexing (OFDM) physical layer.
6. The method of claim 1 , wherein the generalized modulation scheme comprises a single carrier modulation scheme.
7. The method of claim 1 , wherein the first transform comprises a Heisenberg transform and the second transform comprises a symplectic fast Fourier transform.
8. The method of claim 1 , wherein the mapping the information symbols to the two dimensional delay-Doppler plane comprises multiplexing information symbols for different users in the two dimensional delay-Doppler plane.
9. The method of claim 1 , wherein the mapped information symbols in the time frequency plane comprise information symbols for different users that are multiplexed in the time frequency plane.
10. The method of claim 1 , wherein the transmission burst is transmitted by spatially multiplexing transmissions of multiple users using beamforming.
11. An apparatus comprising a processor and transmission circuitry, wherein the processor is configured to implement a method, comprising:
receiving information bits;
generating information symbols from the information bits; and
generating a transmission burst from the information symbols such that the generating the transmission burst corresponds to:
mapping the information symbols to a two dimensional delay-Doppler plane;
applying a first transform to the mapped information symbols in the two dimensional delay-Doppler plane to mapped information symbols in a time frequency plane;
transforming the mapped information symbols in the time frequency plane using a second transform to the transmission burst in a time domain using a generalized modulation scheme.
12. The apparatus of claim 11 , wherein the mapping the information symbols to the two dimensional delay-Doppler plane includes mapping the information symbols along points of a lattice in the two dimensional delay-Doppler plane, wherein the points are separated by a reciprocal of maximum delay along a delay dimension and a reciprocal of a maximum Doppler shift along a Doppler dimension.
13. The apparatus of claim 12 , wherein, during the first transformation, one or more pilot symbols are mapped to at least some of the points of the lattice in the two dimensional delay-Doppler plane.
14. The apparatus of claim 11 , wherein the generating the information symbols includes using at least one of a quadrature amplitude modulation (QAM) and a quadrature phase shift keying (QPSK) modulation.
15. The apparatus of claim 11 , wherein the transmission circuitry is configured to transmit the transmission burst using an orthogonal frequency division multiplexing (OFDM) physical layer.
16. The apparatus of claim 11 , wherein the generalized modulation scheme comprises a single carrier modulation scheme.
17. The apparatus of claim 11 , wherein the first transform comprises a Heisenberg transform and the second transform comprises a symplectic fast Fourier transform.
18. The apparatus of claim 11 , wherein the mapping the information symbols to the two dimensional delay-Doppler plane comprises multiplexing information symbols for different users in the two dimensional delay-Doppler plane.
19. The apparatus of claim 11 , wherein the mapped information symbols in the time frequency plane comprise information symbols for different users that are multiplexed in the time frequency plane.
20. The apparatus of claim 11 , wherein the transmission circuitry is configured to transmit the transmission burst by spatially multiplexing transmissions of multiple users using beamforming.