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SANSA Report Summary

Project ID: 645047
Funded under: H2020-EU.

Periodic Reporting for period 1 - SANSA (Shared Access Terrestrial-Satellite Backhaul Network enabled by Smart Antennas)

Reporting period: 2015-02-01 to 2016-07-31

Summary of the context and overall objectives of the project

The aim of SANSA project is to boost the performance of mobile wireless backhaul networks in terms of capacity and resilience while assuring an efficient use of the spectrum. Recently, a global mobile traffic increase of 11-fold between 2013 and 2018 has been predicted. The industry and research communities are proposing novel access technologies such as millimeter wave access or dense small cell deployments for facing these traffic requirements. However, these technologies impose new challenging requirements to backhaul networks, so novel solutions are required to avoid backhaul becoming the bottle neck of future mobile networks. In this sense, SANSA proposes a spectrum efficient self-organizing hybrid terrestrial-satellite backhaul network based on three key principles: (i) a seamless integration of the satellite segment into terrestrial backhaul networks; (ii) a terrestrial wireless network capable of reconfiguring its topology according to traffic demands; (iii) a shared spectrum between satellite and terrestrial segments. This solution is enabled by two key components. On the one side, low-cost smart antennas deployed in terrestrial nodes allowing the network topology reconfiguration and spatial interference mitigation. On the other side, a hybrid network management scheme for an efficient use of all the network resources, either terrestrial or satellite. This scheme is based on a centralized component, i.e. Hybrid Network Manager, and distributed components deployed at the terrestrial nodes, i.e. Intelligent Backhaul Nodes.
The possibility of offloading backhaul traffic to the satellite and adapting the terrestrial network topology to the traffic needs will permit meeting the project objectives in terms of capacity and resilience to link failures or congestion. In the same way, the spectrum coexistence between the terrestrial and satellite segments will provide the targeted spectrum efficiency improvement. In addition, SANSA also aims to improve the energy efficiency of backhaul networks and to facilitate the deployment of mobile networks both in low and highly populated areas. The former will be achieved thanks to the terrestrial network reconfiguration which allows setting nodes in sleep mode during low demand traffic periods. The later will be met by the extended coverage provided by the satellite which facilitates deployment in remote areas, and by the use of smart antennas with self-pointing capabilities, thus not requiring qualified personnel at installation.
Finally, the SANSA consortium strongly believes that SANSA will set the basis for a win-win collaboration between European terrestrial and satellite operators that will result in the strengthening of both market sectors, generating economic growth and in turn, societal benefits for the European citizens.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

On the technical side, all WP were active WP2 being the only one that concluded within this period. It successfully achieved its goals. In particular, WP2 carried out the study of the current regulation at the targeted Ka band (D2.1) and of the state-of-the-art (SOTA) of backhauling technologies (D2.2), which were the basis on which the consortium defined the relevant use cases, scenarios and KPIs (D2.3, Milestone Ms7). The scenario definition included the derivation and analysis of two benchmark topologies that were used for deriving the requirements of the smart antennas as a SANSA’s key enabling component (D2.4, Ms10), and that will be also used as a basis for demonstrating the achievement of the numerical project objectives in WP3 and WP4. The functional requirements of the other two SANSA’s key enabling components, namely the Hybrid Network Manager (HNM) and the Intelligent Backhaul Node (IBN) were also identified in D2.4. WP2 concluded with the analysis of the theoretical upper bounds for two main SANSA’s KPIs, the aggregated throughput and the energy efficiency.
Within WP3, the task relative to the study of medium access control mechanisms for the SANSA system also concluded successfully. It produced three remarkable outcomes covering both terrestrial and satellite segments: the error performance curves that are currently being used in WP4 for modelling the terrestrial and satellite links (D3.1, Ms11); a novel satellite access mechanism based on the combination of Direct Sequence Spread Spectrum(DSSS) and Slotted Aloha; and a novel cross-layer design of the flow control and link scheduling policies in hybrid terrestrial-satellite wireless backhaul based on STDMA (D3.2). Besides, the task of selecting the most suitable antenna candidate for the SANSA terrestrial nodes is almost completed (D3.3 to be ready at the end of this month). The SOTA and beyond SOTA analysis of different candidates against the requirements specified in D2.4 concluded with the identification of hybrid analog-digital beamforming arrays as the most promising solution in terms of cost/beamforming capabilities trade-off. However, alternative low-cost structures such as parasitic arrays and metasurface antennas require a deeper analysis that will be conducted on WP5. In turn, the project also progressed a lot in the development of novel interference mitigation techniques based on beamforming /precoding. The main focus here was in hybrid analog-digital schemes but other promising techniques such as symbol level precoding, coordinated multi-user/multi-node precoding and precoding over wide-beam antennas for point–to-multipoint links are being addressed. Finally, the consortium initiated the task related to the development of hybrid radio resource management which is expected to produce relevant results in the following weeks.
WP4 was mainly devoted to the definition of the SANSA network architecture and the functionality splits between the two main SANSA network devices, the HNM and the IBN. This task is almost completed with a detailed logical and physical description of the two components. The final architecture definition of the two devices will be delivered in D4.1 at the end of next October and will serve as the starting point for the construction of the proof-of-concept in WP5. In addition, important progress was achieved in the development of some of the identified functionalities. This includes the design of backpressure routing algorithms for the hybrid network which already showed significant throughput and delay improvements, the design of energy saving algorithms based on the capability of enabling and disabling access interfaces, or the development of topology calculation routines. Finally, the task relative to the multicast beamforming towards the terrestrial distribution network was initiated and the first results are expected in the following months.
Since the topology calculations addressed in WP4 are totally affected by physical parameters (e.g. SINR) which are tackled in WP3, the consortium initiated a cross WP3- WP4 activity. The main idea is that the HNM is assisted by a radio environment mapping module which is the responsible for calculating the SINR for each node in each topology according to the beamforming and radio resource management techniques applied (task performed within WP3). The first simulation results of this activity considering full frequency reuse and backpressure routing are already available. In the next period these cross-WP simulations will also integrate the topology calculations performed in WP4. It is important to remark here that this simulations will put together part of the outcomes of WP3 and WP4, reinforcing the cohesion of the project.
Based on the recommendations of WP3, WP5 started the construction of a hybrid-analog digital beamforming antenna. At this stage the antenna element design is completed, the phase shifter and amplifying components are selected and a small element+back–end prototype will be tested in September.
WP6 almost finished the definition of the three demonstrations for evaluating the performance of the three SANSA key enabling components: the smart antennas, the HNM and the IBN. In the meantime WP6 also achieved milestones Ms8 and Ms13, relative to the preparation of the demonstration environment for the OTA test of the antenna prototype and for the emulation of a terrestrial and satellite backhaul network on RF level (OTA and conducted).
WP7 was activate since the beginning of the project carrying out dissemination, standardization and exploitation activities, and produced an initial dissemination, standardization and exploitation plan (D7.1) at the end of the first year. It included an estimation of publications for years 2 & 3, a plan for the organization of SANSA events, the identification of standardization bodies to be followed, and an initial exploitation plan. Since then, the consortium is closely following the plan and the following results have been achieved for this reporting period. On the dissemination side, the consortium published 18 conference/workshop papers and 2 journal papers either focused on some of the developed techniques or giving a general project overview. Besides, the project website disseminated all project activities including meetings, publications, presence in conferences, standardization activities, innovation assets, etc., thus achieving all milestones related to website updates. On the standardization side, the consortium actively contributed to a Working Item of the ETSI SES SCN group and to a 3GPP RAN activity, both devoted to the integration of satellite communications in 5G networks. In addition, SANSA contributed to the discussions of the 5GPPP spectrum and architecture groups, promoting the hybrid-satellite terrestrial network solution.
On the coordination side, WP1 provided all necessary resources for the proper execution of the project (Consortium Agreement, website (D1.1, Ms1), document templates, internal repository, etc.); monitored the preparation of a work plan for each starting task as well as the progress of the active ones, co-organized and chaired four face-to-face meetings with all the consortium participants, coordinated and edited all progress reports (D1.2-4) and coordinated the project’s innovation management including the first SANSA innovation session.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

So far, the progress beyond the state of the art of the SANSA project followed three directions. First, a novel network management scheme for self-organizing hybrid terrestrial-satellite backhaul networks was defined. Two main entities performing all management activities were conceived: a centralized one called Hybrid network manager, and distributed ones located in each network node called Intelligent backhaul nodes. The focus was on designing a solution which could be adopted as seamlessly as possible by the terrestrial network operators, so avoiding the need of rethinking the management procedures of current networks. In addition, novel techniques were developed regarding specific functionalities of the two devices, such as backpressure routing algorithms for hybrid networks, Q-learning algorithms for improving energy efficiency and network topology calculation algorithms.
Second, the project progressed in the development of novel antenna and signal processing techniques for enabling the topology reconfiguration of the SON network and an aggressive frequency reuse among terrestrial nodes, and also among terrestrial and satellite terminals. In these sense, SANSA proposed several signal processing solutions for hybrid analog-digital arrays such as: convex optimization techniques for null–steering; maximization of the spectral efficiency constrained by the interference level created in some directions; and interference mitigation algorithms, which are based on block diagonalization for a multi-base station scenario. Reflectarray antennas were also addressed and two novel solutions proposed: a low complexity method for controlling reflectarray based on addressing the elements by rows and columns; and a novel method for performing null-steering. In the same way, a novel design of an ESPAR antenna at 10 GHz was proposed and robust multi-cell channel aware precoding for this kind of antennas was developed. Finally the project also proposed novel symbol level precoding strategies.
Third, SANSA proposed two novel techniques in the context of MAC mechanisms for the SANSA scenario. In particular, a novel satellite access mechanism based on the combination of Direct Sequence Spread Spectrum(DSSS) and Slotted Aloha; and a novel cross-layer design of the flow control and link scheduling policies in hybrid terrestrial-satellite wireless backhaul based on STDMA (space-time division multiple access) were developed.
So far the impact of the aforementioned advances is restricted to the research community. However, it is expected that through the development of these novel solutions, at the end of the project, the SANSA consortium will be able to demonstrate that a hybrid terrestrial/satellite backhaul network is not only feasible but it also performs better than the existing solutions in terms of capacity, resilience and deployments costs.
In a long term, it is expected that the SANSA solution will support future media content services delivery, using the combination of satellite networks with off-the-shelf terrestrial 4G network. Such strategy leverages the strengths of each individual technology and forms the integrated satellite terrestrial-networks that will maintain long term profitability to deliver new services in line with user always increasing expectations in terms of speed, quality of service and content availability.
SANSA will also provide the industry with the ability to develop new hybrid satellite - cellular backhauling networking scenarios. These scenarios will be built thanks to the definition of the technologies and new products that will be promoted in SANSA. For the first time, SANSA will set up the enablers to guarantee the optimal solution built upon the combination of both access technologies. This is done by incorporating techniques brought from 4G (e.g. SON) to guarantee the best configuration for spectrum sharing and backhaul network adaptation for high traffic loads.
The win-win collaboration between satellite and cellular network solutions built upon SANSA's hybrid network management concept will strengthen the European telecommunication industry based on the CAPEX and OPEX costs reduction for service and telecom operators that will cover seamlessly both access technologies. In particular SANSA outcomes will demonstrate that the satellite segment will become an essential part of mobile networks. This will open new business opportunities for European satellite operators generating economic growth of the European satellite sector. In a similar way, mobile network operators will benefit from SANSA solutions, since they will have new technologies available for addressing the unprecedented traffic demand increase and for improving the resilience of their networks. As a result, they will be able to provide better and faster services to their users which will be translated in increased revenues and in economic growth of the terrestrial mobile operators too. Besides, SANSA will also open new business opportunities for equipment manufacturers of terrestrial and satellite networks, which will be able to develop new product lines to address the technological challenges of the hybrid solution, which will in turn result in increased revenues.
SANSA project will also have a strong indirect impact over the European society. On one side, SANSA hybrid terrestrial-satellite technology will provide support to the ever increasing demands of mobile traffic. Therefore, SANSA will contribute to the appearance of new applications and user trends providing fast internet connection every time and everywhere. On the other side, SANSA will contribute to the economic growth of the European satellite and terrestrial telecommunications industries, which will be translated in new job openings, and thus it will strengthen the welfare state of the European citizens.

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