Multi-G OTFS

OTFS is now widely endorsed by the global research community, leading mobile operators and vendors as a next generation wireless system for hypersonic communication. Cohere has been working with Orthogonal Time Frequency and Space (OTFS) modulation since the inception of the company in 2011. Cohere built an end-to-end wireless OTFS system which demonstrated superior cellular performance – as tested with Telefonica in March 2018 where Cohere’s OTFS system demonstrated spectral efficiency of 57 b/s/Hz across 14 layers in a 90-degree sector. OTFS modulation is part of a larger mathematical theory of communication in the Delay-Doppler domain (in contrast to the classical theory that uses the time frequency domain). Since 2011, Cohere’s innovations have resulted in over 300 patents for OTFS modulation, Delay-Doppler channel modulation, distributed cloud functions and antenna designs.

In 2018, Cohere decided to bring its innovation around the use of Delay-Doppler-based channel detection, estimation and prediction, as well as precoding software to improve 4G and 5G wireless systems. This innovative technology is agnostic to any modulation scheme and is fully compliant with 3GPP. The pioneering work in the Delay-Doppler domain enables robust channel estimation and accurate channel prediction into the future. It alleviates handset feedback requirements by leveraging geometric reciprocity and reduces computation complexity through concise channel representation. All of these features combine to deliver significant spectrum multiplier effect for 4G and 5G networks in both FDD and TDD.

Will 6G Go Hypersonic?
OTFS Delay-Doppler channels are immune to doppler effects. OTFS communications exhibits outstanding performance while operating within the high velocities of Hypersonic objects.

Will 6G Bring Together 5G & 4G in the Cloud?
Accurate channel prediction into the future, that is native to the Delay-Doppler domain, enables orthogonal beam scheduling across multiple DUs. The same Delay-Doppler principles that enable the spectrum multiplier effect are applied to schedule orthogonal beams from multiple DUs in same spectrum.

Will 6G Bring Together Earth and Satellite Communications?
OTFS Delay-Doppler channels are immune to doppler effects. OTFS communications exhibits outstanding performance while operating within the high velocities of Low Earth Orbit (LEO) satellite constellations. Other valuable characteristics of OTFS such as a higher SNR, better immunity to fading or interference, and MIMO beamforming are also vital for satellites to process weak signals from terrestrial devices.

Will 6G increase network capacity?
Our Universal Spectrum Multiplier xApp that has demonstrated up to 2x gains in spectral capacity is based on the Delay-Doppler channel model. This channel model has been extracted from the OTFS platform. Because the Delay-Doppler channel model is independent of the OTFS waveform, it can be applied to both 4G and 5G.

What is a Pulsone?
The term Pulsone describes the OTFS waveform carrier. It is “the fusion of a tone and a pulse” related through the Zak Transform. A Pulsone holds its shape when shifted in time or in frequency (Doppler shift), thus, it is invariant to distortion and delay from Doppler shift. This characteristic is valuable when communicating with fast moving objects that exhibit very high Doppler shift such as Low Earth Orbit satellites or hypersonic aircraft moving in Earth’s atmosphere.

The videos below provide foundational theoretical information on the OTFS system, the Pulsone waveform carrier, and operating in the Delay-Doppler domain. OTFS is a breakthrough that enables the use cases of “Multi-G” that cannot be addressed by today’s time-frequency model.