SMArT

Every year, the European Commission (EC) conducts a study to monitor the progress of European member states toward the broadband coverage objective: ‘Broadband Coverage of 50% of households with speeds at least 100 Mbps by 2020’. The study performed in 2017 reveals that 8% of the homes in the rural areas are not covered by any fixed network and 53% are not covered by any wired Next Generation Access (NGA) technology, such as VDSL, Cable Docsis 3.0 and FTTP 4. This is
due to the low economic profitability of investments in broadband access infrastructure in rural areas with low population density. As a result, the gap between the total NGA coverage and the rural NGA coverage is much larger at 33.2% in 2017. Despite the efforts made to minimize the gap, the significantly lower rate of the NGA network deployment in rural areas leads to a very large broadband divide between urban and rural areas. The broadband divide has been widening not only in EU, but also in other developed countries as well as developing countries across the world. The Middle East, North Africa and sub-Saharan Africa have not matched the advanced trends in broadband internet access and the broadband divide is increasingly becoming the knowledge divide.

To close the broadband divide and to provide ultra-fast broadband in rural areas, there is a need to devise new fixed access technologies that requires low investment from the telecom operator and no additional cost overhead from the end user. Since the current wired NGA technologies do not fulfill these requirements, the only promising solution is to devise extensions to the 5G LTE technology to provide wireless broadband access. This can currently be done with a central 5G base station communicating wirelessly to a

3GPP-compliant Customer Premise Equipment (CPE), such as Home outdoor modem, wall-mounted to the end-user home as shown in the Figure above. The main advantage of such a fixed wireless access solution compared to NGA technologies is the relatively low investment as mobile operators can re-use the installation of 5G base stations or install an additional one to cover houses within a radius of few kilometers instead of laying underground cables over the rural terrain. Although fixed wireless access solution sounds promising for rural broadband access and economically viable from the perspective of mobile operator, two main challenges need to be addressed to close the bandwidth divide:

1. Achieve over ten-fold (10X) improvement in data rates; (i.e. up to 10 Gb/s) between the base station and the home outdoor modem, compared to state-of-the-art NGA technologies7,8,9.
2. Maintain a low power consumption of the home outdoor modem; as the energy for powering the modem is continuously derived from the home unlike a base station powered by the industry.

Thanks to the sub-6 GHz 5G mobile broadband technology that operates on much wider licensed spectrum compared to the existing 4G technology, it is theoretically possible to achieve over 10X improvement in data rates even though such high data rates are not promised by any proposed variant of the sub-6 GHz 5G standard. This can be realized only with ultra-wideband transceivers operating in the sub-6 GHz licenced band.
However, the bandwidth specification for such transceivers in the User Equipment (UE), home outdoor modem in this case, will be several orders more stringent than that of the conventional mobile UE (5G mobile phone) to achieve the desired data rate. The transceiver design for a regular mobile UE in 5G systems is already very challenging due to techniques like Massive MIMO and Beamforming that are integral part of the 5G standard. When this is combined with the ultra-wide bandwidth specification required to achieve the desired data rate as well as the constraints imposed by the power budget of the home outdoor modem, the design of transceiver circuits for the proposed system becomes extremely challenging. Clearly, the conventional analog design methodologies traditionally employed in the design of wireless transceivers proves insufficient to realize the system, necessitating a fundamental paradigm shift. With this proposal, we seek to explore the possibilities offered by a novel approach to transceiver design where analog signal processing is achievedentirely with digital components by representing analog signals using time-based signal parameters instead of using voltage/curren/charge like in conventional circuits.

The SMArT project has thus two main aims:

Aim 1: Develop technology for energy-efficient ultra-wideband transceivers to enable 10Gb/s 5G home outdoor modem: SMArT project will develop ground-breaking transceiver technologies for 5G and beyond, with an immediate emphasis on the requirements for energy-efficient 10Gb/s home outdoor modem to provide high-speed fixed wireless internet aceess to rural areas.

Aim 2: Train future researchers through active industry–academia collaboration: SMArT will create a platform to train a new generation of innovative Early Stage Researchers (ESRs) through technology development to address the industrial demand for highly skilled researchers required to shape future communication systems. The active collaboration of academia and industry in the training activities as well as in the technology development will empower the ESRs with a unique mix of highly valued transferable research skills and application-focused industry perspective.

Publications

"Digital Predistortion with Compressed Observations for Cloud-Based Learning", https://researchportal.tuni.fi/en/publications/digital-predistortion-with-compressed-observations-for-cloud-base