The future traffic demands will require the deployment of new communication systems with faster as well as more efficient and reliable connections. The new 5G systems will represent a significant improvement over 4G systems, increasing the speed of LTE-Advanced by 1000. To increase channel capacity, the distribution of ultra-dense networks of base stations, the use of new frequency bands, such as millimeter-wave (mmWave), and the combination of beamforming techniques and advanced MIMO systems arise as a requirement. In this scenario, the knowledge of the radio channel holds the key to define the standard, select new frequency bands, and optimize the deployment of the network infrastructure.

With the aim of studying the radio channel properties for the new 5G scenarios, the project ICAR5G started in 2018. The objectives of this project are to generate new radio channel models based on extensive measurement campaigns, complementing the actions being already developed in other projects, to evaluate the different technologies to be implemented in the radio interface and to optimize the deployment of base stations. In addition, this knowledge is intended to assist decision-making in the process of reorganization and assignment of frequencies in future 5G systems by the standardization and radio spectrum management bodies.

Up to now, extensive channel measurements in underground and indoor office environments have been collected using a novel channel sounder implemented in the frequency domain and based on the use of radio over fiber (RoF) links with omnidirectional antennas. From the channel measurements, realistic channel models have been analyzed and developed in the potential frequency bands to deploy the future 5G systems, with special attention to mmWave, e.g., 26, 28, 38 and 60 GHz. These models have been compared with ray-tracing techniques to develop diffuse scattering models. The performance of multiuser MIMO techniques, that can be introduced into 5G systems, have also been investigated in these particular environments from the channel models.

Antennas, Microwaves and Propagation

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