Santa Clara, Calif.-based Cohere Technologies is going up against some big competition in its drive to get the standards community to consider using a 5G air interface based on Orthogonal Time Frequency and Space (OTFS) rather than Orthogonal Frequency Division Multiplexing (OFDM)-based technology.
Several proposals for a 5G air interface are expected to come from the likes of Nokia (NYSE:NOK), Qualcomm (NASDAQ:QCOM), Ericsson (NASDAQ: ERIC) and Huawei, and Cohere plans to be right there with them as the 3GPP considers proposals. That said, Cohere executives also say their technology co-exists nicely with OFDM and its proposal will include a graceful migration from 4G to 5G, with some added benefits to be drawn from OTFS.
Unlike the one-dimensional channels currently used in LTE networks, Cohere describes OTFS as a paradigm shift in wireless networking that creates a two-dimensional view of the delay and Doppler of the wireless channel. Cohere Technologies CEO Shlomo Rakib said he learned about OTFS from a professor at the University of Texas at Austin and started exploring how it could be applied in wireless. That teacher, Ronny Hadani, is now the CTO of Cohere.
Rakib says the philosophy of OTFS is different from OFDM, in part because OTFS contains an element to spread information across time and frequency, which allows signals to benefit from diversity in the channel while also penetrating through material like concrete and glass. The way it's configured, OTFS is immune to fading, multipath and other signal impairments that plague conventional modulations.
While Cohere Technologies says it is preparing to produce Massive MIMO radios that include 64 x 64 antenna arrays, the company's trials use currently available MIMO radios with 2 x 2 and 4 x 4 antenna arrays. The tests it conducted spanned urban settings with tall buildings, mountainous regions, rural settings and moving vehicles, all at various distances, with and without line-of-site configurations.
The company says that while OFDM-based radios used for comparison would fade, drop signals or lose capacity, the OTFS radios never faded – even at distances beyond 4 km – and maintained connectivity even in the most challenging mobile scenarios. The tests were able to maintain a minimum of 4bps/Hz in 10 MHz achieving at least 120 Mbps up to 320 Mbps.
Cohere is currently focused on the 3.5 GHz space, but it says its technology is perfect for the high-band millimeter wave spectrum bands that are being eyed for 5G services. It so happens that 3.5 GHz is lightly licensed and the focus of the FCC's plans to use a Spectrum Access System (SAS) for sharing in what it's been calling the innovation, or CBRS, band.
The green pin at the top is Cohere's headquarters. The seven different nodes are located in a mixed residential area Santa Clara, Calif. The tests were conducted in 3.5 GHz using 2x2 MIMO radios. (Image source: Cohere)
The company is working with multiple carriers in trials but isn't in a position to name them. Rakib told FierceWirelessTech that it's also hard to say exactly who Cohere competes with because its business model is still emerging.
He said the company's main goals for this year include the successful deployment of the company's products in field trials with as many carriers as possible, as well as getting OTFS considered as part of the new proposed 5G air interface. Cohere plans to participate in the 5G standards-setting process and will attend an upcoming 3GPP meeting where participants are expected to talk about their expectations for 5G.
That's where the company also will be competing with much larger companies. Huawei, for one, has proposed its non-orthogonal access technology based on Sparse Code Multiple Access (SCMA), and Filtered-OFDM.
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