The technical activities of SANSA were focused, on the on hand, on the specification of the network architecture, the development of the main functionalities of the HNM and IBN entities and their evaluation with NS3 simulations. In particular, SANSA developed: (i) a novel backpressure hybrid algorithm and evaluated it in rural and dense urban scenarios against state-of-the-art solutions; (ii) a novel topology manager capable of providing alternative topologies in the presence of congestion or link failure events; (iii) an energy saving agent based on a distributed q-learning solution for dense scenarios based on small cells equipped with energy harvesters; and (iv) a new algorithm enabling to combine link selection capabilities with traffic classification techniques enabling an efficient offloading of terrestrial traffic. The combination and smart orchestration of these functionalities provided noticeable performance improvements to backhaul networks. Specifically, aggregated throughput gains up to 35% and latency improvements for delay non-tolerant traffic of 150%, as well as energy saving up to 37% were demonstrated in a realistic scenario based on a real network deployment close to Helsinki. In addition, SANSA also explored a hybrid terrestrial/satellite caching scheme for content delivery networks, which enable drastic bandwidth savings in terrestrial backhaul networks.
On the other hand, SANSA developed interference mitigation techniques enabling an efficient use of the spectrum. SANSA explored multi-antenna beamforming and nulling solutions with the focus on low cost/low complexity schemes. Hence, SANSA studied low cost antenna technologies such as hybrid analog-digital arrays, reflectarrays, metasurface antennas and parasitic arrays, as well as an extensive range of beamforming strategies covering point-to-point, point-to-multipoint and multipoint-to-multipoint situations. Beamforming algorithms were evaluated in the realistic Helsinki scenario providing network spectral efficiency (NSE) gains up to 3.5x which could be extended to 9x in the case the channel characteristics permit multi-stream transmissions. These gains were upper bounded by the original number of carriers used in the benchmark scenario and reused thanks to SANSA solutions. NSE gains above 10x could be envisaged in future dense deployments. SANSA complemented the multi-antenna techniques with the development of dynamic and hybrid resource management solutions.
After the promising results obtained at simulation level, SANSA proceeded to the experimental validation of its two main enabling components. To this end, a hybrid analog-digital array prototype was developed and used in the over-the-air demonstration of the spectrum coexistence of a satellite and a terrestrial link. The antenna prototype in combination with the developed beamforming algorithms successfully protected a closely located satellite receiver, which was able to reproduce a received video with high quality. In addition, a HNM and IBN prototypes were evaluated in a pure virtual network emulation at IP level. It permitted demonstrating the improved resilience of SANSA networks thanks to the capabilities of the HNM/IBN to adapt the network topology to the traffic status and demands, thus solving congestion and link failure events.
These technical activities were disseminated in 4 SANSA events, 16 scientific journals, 58 conference/workshop papers and in 2 book chapters. In addition, spectrum sharing results were disseminated to regulatory bodies such as CEPT FM 44 group or the Hellenic Telecommunications and Post Commission (EETT). SANSA also contributed to two working groups in ETSI SES SCN and in 3GPP SA1 related to the integration of satellites in 5G. On the exploitation side, the project produced two patent fillings, analysed a successful business case for the SANSA solution and detailed a roadmap for bringing SANSA to the market in the next future.
