# US 12,184,468 B2 · Orthogonal time frequency space modulation techniques > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,184,468 B2 - Document ID: US12184468B2 - Status: Granted - Kind: B2 - Application number: 18/409,482 - Filed: 2024-01-10 - Published: 2024-06-06 - Granted: 2024-12-31 - Earliest claimed: 2015-11-18 - Assignees: Cohere Technologies, Inc. - Applicants: Cohere Technologies, Inc. - Inventors: Ronny Hadani; Shlomo Selim Rakib; Anton Monk; Michail Tsatsanis; Yoav Hebron - Web page: https://patentgrep.com/patent/US12184468B2 ## CPC - H04L 27/32: Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26 - H04L 27/18: Phase-modulated carrier systems, i.e. using phase-shift keying (H04L27/32 takes precedence) - H04L 27/2639: {Modulators using other transforms, e.g. discrete cosine transforms, Orthogonal Time Frequency and Space [OTFS] or hermetic transforms} - H04L 27/2697: {in combination with other modulation techniques} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract 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. ## Claims ### Claim 1 A wireless communication method, comprising: receiving multiple data streams, each data stream representing data for a separate user equipment; generating information symbols by multiplexing the multiple data streams; modulating the information symbols onto one of a set of two dimensional (2D) orthogonal basis functions that span at least a portion of bandwidth and time duration of an orthogonal time frequency space (OTFS) frame, wherein the set of 2D orthogonal basis functions comprises OTFS basis functions along a delay dimension and a Doppler dimension; and further processing and transmitting a transmission burst using a universal filtered multi-carrier (UFMC) technique, wherein modulating the information symbols includes placing each information symbol on a grid along the delay dimension and the Doppler dimension, and wherein at least one pilot symbol on the grid is surrounded by a rectangle of unused grid points. ### Claim 2 (depends on 1) The method of claim 1, wherein the modulating includes performing a quadrature amplitude modulation (QAM) or a quadrature phase shift keying (QPSK) modulation. ### Claim 3 (depends on 1) The method of claim 1, wherein the modulating includes giving different ones of the set of 2D orthogonal basis functions within the OTFS frame to each user equipment to achieve multiplexing of the multiple data streams. ### Claim 4 (depends on 1) The method of claim 1, wherein the modulating each of the information symbols includes: applying window functions to the set of 2D orthogonal basis functions to generate windowed basis functions; and modulating each of the information symbols using a corresponding windowed basis functions. ### Claim 5 (depends on 1) The method of claim 1, wherein the modulating the information symbols includes: multiplying, using a symplectic Fourier transform, each information symbol with a corresponding 2D orthogonal basis function; and superpositioning results of the multiplying for the information symbols. ### Claim 6 A wireless communication apparatus, comprising a processor configured for: receiving multiple data streams, each data stream representing data for a separate user equipment; generating information symbols by multiplexing the multiple data streams; modulating the information symbols onto one of a set of two dimensional (2D) orthogonal basis functions that span at least a portion of bandwidth and time duration of an orthogonal time frequency space (OTFS) frame, wherein the set of 2D orthogonal basis functions comprises OTFS basis functions along a delay dimension and a Doppler dimension; and further processing and transmitting a transmission burst using a universal filtered multi-carrier (UFMC) technique, wherein modulating the information symbols includes placing each information symbol on a grid along the delay dimension and the Doppler dimension, and wherein at least one pilot symbol on the grid is surrounded by a rectangle of unused grid points. ### Claim 7 (depends on 6) The apparatus of claim 6, wherein the modulating includes performing at least one of a quadrature amplitude modulation (QAM) or a quadrature phase shift keying (QPSK) modulation. ### Claim 8 (depends on 6) The apparatus of claim 6, wherein the modulating includes giving different ones of the set of 2D orthogonal basis functions within the OTFS frame to each user equipment to achieve multiplexing of the multiple data streams. ### Claim 9 (depends on 6) The apparatus of claim 6, wherein the modulating each of the information symbols includes: applying window functions to the set of 2D orthogonal basis functions to generate windowed basis functions; and modulating each of the information symbols using a corresponding windowed basis functions. ### Claim 10 (depends on 6) The apparatus of claim 6, wherein the processor is further configured to perform the modulating by: multiplying, using a symplectic Fourier transform, each information symbol with a corresponding 2D orthogonal basis function; and superpositioning results of the multiplying for the information symbols. ### Claim 11 A wireless communication method, implemented at a user equipment, comprising: receiving and processing an orthogonal time frequency space (OTFS) frame that includes information symbols for multiple user equipment that are multiplexed using a multiplexing scheme; recovering, from the OTFS frame, information symbols based on one of a set of two dimensional (2D) orthogonal basis functions that span a portion of a bandwidth and a time duration of the OTFS frame, wherein the set of 2D orthogonal basis functions comprises OTFS basis functions defined along a delay dimension and a Doppler dimension wherein the OTFS frame was received using a universal filtered multi-carrier (UFMC) technique, wherein the information symbols are recovered from a grid along the delay dimension and the Doppler dimension, and wherein at least one pilot symbol on the grid is surrounded by a rectangle of unused grid points; and recovering information bits by demodulating the information symbols. ### Claim 12 (depends on 11) The method of claim 11, wherein the demodulating includes performing at least one of a quadrature amplitude modulation (QAM) demodulation or a quadrature phase shift keying (QPSK) demodulation. ### Claim 13 (depends on 11) The method of claim 11, wherein the demodulating includes: performing a matched filtering operation on a portion of the OTFS frame assigned to the user equipment, followed by a symplectic fast Fourier transform operation to generate time-frequency samples of the information symbols. ### Claim 14 (depends on 11) The method of claim 11, wherein the receiving includes receiving the OTFS frame in a transmission burst using an orthogonal frequency division multiplexing (OFDM) physical layer or a Long Term Evolution (LTE) physical layer. ### Claim 15 A wireless communication apparatus, comprising a processor, wherein the processor is configured for: receiving and processing an orthogonal time frequency space (OTFS) frame that includes information symbols for multiple user equipment that are multiplexed using a multiplexing scheme; recovering, from the OTFS frame, information symbols based on one of a set of two dimensional (2D) orthogonal basis functions that span a portion of a bandwidth and a time duration of the OTFS frame, wherein the set of 2D orthogonal basis functions comprises OTFS basis functions defined along a delay dimension and a Doppler dimension wherein the OTFS frame was received using a universal filtered multi-carrier (UFMC) technique, wherein the information symbols are recovered from a grid along the delay dimension and the Doppler dimension, and wherein at least one pilot symbol on the grid is surrounded by a rectangle of unused grid points; and recovering information bits by demodulating the information symbols. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the set of orthogonal basis functions comprise an OTFS transform. ### Claim 17 (depends on 15) The apparatus of claim 15, wherein the processor is further configured for demodulating by performing at least one of a quadrature amplitude modulation (QAM) demodulation or a quadrature phase shift keying (QPSK) demodulation. ### Claim 18 (depends on 15) The apparatus of claim 15, wherein the processor is further configured for demodulating by performing a matched filtering operation on a portion of the OTFS frame assigned to the user equipment, followed by a symplectic fast Fourier transform operation to generate time-frequency samples of the information symbols. ### Claim 19 (depends on 15) The apparatus of claim 15, wherein the OTFS frame is received in a transmission burst using an orthogonal frequency division multiplexing (OFDM) physical layer or a Long Term Evolution (LTE) physical layer.