Leti, a research institute of CEA Tech, and CloudNet IT-Solutions, a Scottish SME specializing in TVWS (TV White Space), on December 18, 2017, announced field trial results for a new flexible multicarrier system in the Orkney Islands designed to demonstrate a new post-OFDM (orthogonal frequency-division multiplexing) multicarrier waveform.
The trial showed that the post-OFDM multicarrier waveform, a block filtered-OFDM (BF-OFDM), can overcome all shortcomings inherent in actual OFDM waveforms (WiFi/LTE) and is backward compatible with existing receivers.
“The results of these field trials enhance Leti’s technology-to-system offer for its industrial partners in the context of telecom applications and ad-hoc proprietary radio solutions for vertical sectors,” said Dimitri Ktenas, Leti wireless lab manager. “Leti’s patented technology unlocks the usage of spectrum sharing, such as License Shared Access in TVWS and CBRS (Citizens Broadband Radio Service) at 3.5GHz.”
Leti was granted in January 2017 an 18-month license from Arcep, France’s telecommunications regulatory agency, to run a field trial with multiservice transmission at 3.5 GHz TDD band, and continues to deploy its patented multicarrier technology on broadband wireless channels. In the Orkney Islands field trial, Leti demonstrated the flexibility as well as the performance of the technology in terms of spectral efficiency in the 700 MHz TVWS band for rural broadband and maritime broadband radio scenarios. The measurements were supported under the framework of the H2020 EU-funded GateOne project.
Leti’s post-OFDM multicarrier waveform is designed to achieve good frequency localization and support simultaneous single-carrier and multicarrier modulations, along with classical multi-antenna systems, e.g. multiple-input/multiple-output (MIMO) solutions. The duration of the elementary communication slot is configurable and can be adapted to the targeted latency and channel conditions. In addition, classical multi-user (MU) access can be used on top of it, and even combined with MIMO, leading to MU-MIMO technologies in fragmented spectrum scenarios.
The Orkney Islands deployment assessed the performance of a broadband transmission in a 16MHz fragmented spectrum channel while fitting with ETSI EN 301 598 TVWS regulation. The measurements performed at the beginning of November strongly validated the trial’s innovative concepts in a real-life situation. Rural broadband content delivery was demonstrated up to 20km, using non-contiguous channels. Leti’s over-the-air versatile and portable test platform based on field-programmable gate arrays (FPGA), ARM processors and agile RF front-end was used to demonstrate a broadband transmission. The same set of equipment is also part of the 5G Leti testbed under evaluation in the future 5G 3.5GHz band.