Researchers in France are preparing a trial that will add more grist to the debate over waveforms for the air interface of 5G cellular.
CEA-Leti will begin next month a field trial of a multicarrier waveform it developed using the block-filtered version of OFDM. It is betting the format will be chosen from among many as the standard for the 5G air interface at sub 6GHz applications
The French telecommunications regulatory agency Arcep gave the institute a six-month licence to run a service at its Minatec campus in Grenoble. The trial will run in the 3.5GHz TDD band with 40MHz bandwidth.
“There are of course many, many laboratory and some field trials of the potential waveforms that could be used for 5G here in Europe and the rest of the world, but we believe this is the first to focus on a multicarrier, multi-service set-up in real-life situations,” Dimitri Ktenas, wireless lab manager at Leti told EE Times.
The over-the-air test platform is based on FPGAs, ARM processors and an off-the-shelf RF front end from Analog Devices, according to Ktenas. It uses a modular design to test 5G multiservice transmission for a mix of mobile broadband, cellular IoT and low latency communications.
The test will use two base stations and several types of user equipment, though Ktenas would not elaborate on specific use cases. The subscriber gear is based on a proprietary small form-factor baseband board. “We will also look at multiuser access with a technique that exploits the promising characteristics of frequency localization and agility,” he said.
The MAC layer will be able to adapt so that the channel can be shared with a coexisting system and thus provide a means to enable enhanced dynamic spectrum access.
The trial also will investigate a high spectral efficiency gains in-band full duplex (IBFD) technique. IBFD allows data to be transmitted and received in the same frequency band simultaneously, theoretically doubling the data rate.
Ktenas cautions that implementations of IBFD to date have not shown the anticipated gains with this technique, mainly due to self-interference between signals. Leti’s solution merges three approaches to mitigate this self-interference ---antenna isolation, RF cancellation circuits and non-linear digital filtering.
“On this particular project we are working on our own, but we also participate in numerous collaborative projects investigating 5G, and in particular those focusing on developments on waveforms,” said Ktenas.
“We see this as a first step. Once proven, we plan to discuss the potential to test the technology on a larger test bed with both other research organizations and companies. Ultimately, of course, the aim is to sell the IP related to the technology--that is the business model of the organization,” he said.
Leti also is active in the Fantastic-5G project that started two years ago under the auspices of the European Commission within the Horizon 2000 initiative. The project includes operators Orange and Telecom Italia, the Fraunhofer Institute, Alcatel-Lucent, Nokia, Huawei (Germany), Samsung (UK) and chip suppliers Intel (Germany) and France’s Sequans.
The focus of the project is to devise a single modular air interface that would support all use cases concurrently. It aims to enable parameterizing different parts of the band and related functions.
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