Radio technologies for ubiquitous communications in the evolution from 5G to 6G
Total activity: 2
Type of activity
AGENCIA ESTATAL DE INVESTIGACION
Funding entity code
In 2018, the first release of 5G New Radio was ready driven by the increasing capacity demand, productivity from industry, and importance of Internet of Things. Now that the first 5G networks are being launched, the research community is discussing about open questions related to the evolution to 6G. Future networks will have to cope with completely new applications like cross-reality, telepresence, autonomous vehicles, accurate indoor positioning, etc. This will increase the data traffic, diversity of services, multiplicity of scenarios and number of connected devices, posing extremely stringent requirements (beyond those already defined for 5G) on spectral efficiency, ubiquitous coverage, end-to-end latency, reliability and energy efficiency, in scenarios ranging from outdoor to indoor, from vehicular to wearables. According to the previous issues, the project ROUTE56 has defined a set of objectives to cope with the previous challenges, as explained in what follows. Although future 6G networks will still utilize low frequencies, super-efficiency and short-range connectivity will be key for increased spectral efficiency. The use of wider bands at very high-frequencies (mmWave or THz), the dense deployments of terminals and new massive MIMO concepts are promising solutions in that direction. They demand the study of new channel models in the far- and near-fields, the blocking effects and a better understanding of the behavior of extremely large antenna arrays. Ubiquitous coverage entails the development of new, albeit simple and accurate, coverage prediction tools for very high frequencies and innovative solutions based on passive antenna elements that transform the properties of the channel conveniently. In addition to terrestrial networks, those based on satellite and unmanned aerial vehicles will allow to meet coverage and capacity requirements in remote or highly congested areas. An effective joint transmission and mobility management is crucial to guarantee seamless connectivity. Extreme energy efficiency will also be essential and particularly challenging. For each service type (mobile broadband, ultra-reliable lowlatency and massive machine-type communication), a tailored transceiver design should exhibit high energy efficiency and yet low spectral efficiency loss. Also, opportunistic charging of batteries from ambient interference and through explicit wireless power transfer (WPT) are promising ways of increasing the autonomy of terminals. End-to-end latency will also be critical in 6G. Among the many causes of latency, a proper design of handover and mobility management assisted by network data can make a substantial difference. To that end, distributed artificial intelligence (AI) is expected to be central in learning the static and dynamic components of the radio environment. For example, AI could accurately decide on optimal handover and radio resource allocation by a proper prediction of events. Some of the problems and applications will require extremely precise positioning in harsh scenarios not possible in traditional networks. In this sense, dense cell-free wireless networks with high-frequency antenna arrays have an inherent localization potential to provide high resolvability and accurate 6-dimensional positioning. Sensing the environment and tracking users mobility will enable ultra-short handover latencies and identify areas with more density of battery-limited devices towards which WPT could be directed.