NeTS: Small: Massive Wireless Random Access: Principles and Protocols

Stanford University, Stanford CA

Investigators

Abstract

The next generation of wireless systems are widely expected to connect a massive number of low-energy sensors and actuators that form the fabric of smart technologies and cyberphysical systems. The resultant 'Internet of Things' is expected to be one of the major drivers of technological growth over the next decade. However, its design presents new challenges to wireless engineers. One of the key challenges is how to enable a massive number of low-energy wireless devices to sporadically access the scarce spectrum with minimal coordination and channel estimation overheads. While there are several existing solutions for random access, they are not well-suited for this emerging paradigm due to high energy cost for retransmissions and carrier sensing, near-far effects, or significant control layer overheads. This project aims to fundamentally rethink wireless random access for IoT networks by identifying the sporadic access of a massive number of severely energy limited devices as its key distinguishing characteristic. It develops a mathematical framework to study this problem and shows how this framework relates to a seemingly unrelated problem in theoretical computer science called group testing. By building on this connection it aims to develop optimal mathematical solutions that can be translated to innovative random-access protocols which (a) jointly optimize control and information layer tasks, such as device discovery and data transmission; (b) embrace sensor collisions and thus, eliminate the complexity and energy cost of collision resolution and retransmissions; (c) are designed to satisfy stringent energy constraints and match the energy dynamics at the transmitters; (d) employ simple modulation and detection techniques that do not require channel estimation; and (e) are low-complexity (encoding/decoding), flexible (can be applied in heterogeneous settings), and resilient to noise and device imperfections. The multi-disciplinary nature of the formulated problems will enable the cross-fertilization of ideas from different sub-disciplines of electrical engineering, computer science and applied mathematics. The project is complemented with a strong education and outreach program with an emphasis on broadening participation in electrical engineering. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.