OTOSiS is a research project funded by the Ministerio de Economía y Competitividad of Spain under the research call 2013 Proyectos I+D+i “Retos Investigación”. It concerns the development of realistic performance limits as well as the proposition of physical-layer signaling schemes for next-generation wireless communication systems.

The surge in the use of broadband services combined with the growth of machine-type communication poses high demands on future wireless networks, from the core (backhaul) to the periphery (cellular base stations). Network operators predict that network throughput will have to increase by two to three orders of magnitude by 2020 to match future demands. The required throughput gains can be achieved only by a denser and heterogeneous deployment of the wireless network infrastructure. Under this scenario, interference management, which requires the exchange of control information, becomes crucial. While the control overhead due to exchange of control information in currently deployed wireless networks is negligible, the situation is different in the envisaged dense and heterogenous communication networks. In fact, in certain scenarios, the control-information overhead may outweigh the potential throughput gains. Hence, control-information appears to be the actual bottleneck towards the achievement of the throughput objectives of future broadband networks.

This project advocates a paradigm shift in the way control information is treated in wireless networks. Our philosophy is to view the amount of overhead due to control information as a crucial metric to assess the optimality of physical layer schemes, rather than just an accessory. We will investigate the cost of acquiring network knowledge in dense heterogeneous networks from a fundamental perspective, taking the latency constraints associated with different traffic typologies into account. By studying the information-theoretic limits of wireless networks, we will be able to describe their fundamental overhead-throughput-latency tradeoff. Using these limits, system designers will be able to perform a global wireless network optimization, thereby achieving unparalleled throughput and energy efficiency. We will further propose physical layer signaling schemes that optimally trade overhead, throughput, and latency.

To achieve these objectives, we shall consider the following basic problems:

1. We will take a new look at the problem of modeling dense heterogeneous networks. In contrast to existing models for wireless communication networks, which are typically oversimplified generalizations of models for point-to-point links, our model will be explicitly tailored to realistic wireless networks. Consequently, it will capture the relevant limitations in such networks more accurately, and it will be free of modeling errors introduced by generalizing the point-to-point channel models to networks.
2. We will determine the information-theoretic limits of wireless networks under realistic assumptions. To address latency constraints, we will replace the asymptotic approach that lies at the foundation of currently available information-theoretic analytical frameworks by more sophisticated non-asymptotic tools.
3. We will propose physical layer signaling schemes that approach the obtained information-theoretic limits. At a later stage, the signaling schemes developed in this project will be assessed on a hardware testbed through over-the-air tests.