The solution envisaged by SANSA in order to meet the project objectives, and especally to avoid the "capacity crunch" in backhaul networks, is based on a self-organizing hybrid terrestrial-satellite backhaul network operating at the microwave region (Ka band) based on the following key principles:
- A seamless integration of the satellite segment into terrestrial backhaul networks
- A terrestrial wireless network capable of reconfiguring its topology according to traffic demands
- Spectrum coexistence between satellite and terrestrial segments.
Why a satellite? Because the integration of the satellite component with the terrestrial backhaul network not only provides the evident benefits in terms of easy and cost efficient network deployment in rural or remote areas, but it also enables data off-loading from the terrestrial network, which in turn results in overall capacity increase. Besides, it also provides a new path for routing the traffic that increases the network resilience against link failures or congestion in hotspots.
Why a self-organizing terrestrial network? Because it allows adapting the network topology to the traffic demands, routing the traffic to less congested links which results in a net capacity increase. It also provides the capability of skipping too congested or failed links for an improved network resilience. Besides, it enables the use of energy aware routing algorithms capable of reducing the overall energy consumption by setting different network nodes in sleep mode during low demand traffic periods. Moreover, it reduces the need of an exhaustive radio planning of the whole network.
Why spectrum coexistence of the two segments? Because frequency spectrum is a scarce resource that should be used in the most efficient way. Satellite operators are already demanding more spectrum for other applications such as broadcasting, so there is not so much bandwidth left for mobile backhauling. SANSA will focus its research effort on Ka band where terrestrial backhauling bands of 18 GHz and 28 GHz are shared with the satellite-to-Earth and Earth-to-satellite satellite bands, respectively. The choice of this frequency bands have been made because they are already used in both terrestrial and satellite communications and current regulation already allows coexistence on a coprimary basis there. However, SANSA solution will be easily exportable to other frequency bands.
This solution entails many system design challenges that will be solved by the development of the following disruptive technologies:
- Low cost antenna beamforming solutions for interference management and network topology reconfiguration
- Smart dynamic radio resource management techniques for hybrid terrestrial-satellite networks
- Database-assisted shared spectrum techniques
- Interoperable and self-organizing load-balancing routing algorithms
- Energy efficient traffic routing algorithms
- Satellite Multicast beamforming towards the terrestrial distribution network
SANSA will rely in two key enabling components, which will be implemented and demonstrated in a proof-of-concept during the project:
- Low cost smart antennas, which will be deployed in every terrestrial backhaul node enabling interference management through beamforming as well as network topology reconfiguration.
- Hybrid network manager, which will be deployed in hybrid terrestrial-satellite nodes enabling the efficient use of all the network resources in order to improve capacity and energy efficiency.