NeTS: Small: Collaborative Research: Fine-Grained Spectrum Access for Carrier-Aggregation Based Wireless Networks

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

Dynamic spectrum access brings great benefits for users in overcrowded radio spectrum to opportunistically harvest spectrum resources, which is especially useful for high date rate applications such as video conferencing and multimedia streaming. Since available spectrum may be fragmented, carrier aggregation becomes a critical enabling technique. Many recent and emerging protocols (e.g., 802.11ac WiFi, 802.11af TV whitespace networks, 3GPP LTE unlicensed, and 802.11ay millimeter-wave networks) have been incorporating carrier aggregation mechanisms. However, these mechanisms are still preliminary and heavily rely on conventional MAC/PHY which is designed for nodes sharing the same contiguous channel. As carrier aggregation networks evolve to new generations, three inherent problems will become the fundamental barrier to their efficiency, fairness, and scalability: (i) a transmitter is unable to sense medium state during transmission, (ii) more users and high spectrum dynamics worsen the medium access contention, and (iii) the need of fast spectrum agreement to aggregate multiple fragmented spectrum chunks. The objective of this research is to explore general primitives to effectively realize carrier aggregation with three research components: (i) Migrate the spectrum sensing paradigm from "detect and then transmit" to "simultaneously transmit and detect". The end goal is to overcome the efficiency and fairness problems in standard spectrum sensing mechanisms to enable asynchronous, out-of-band OFDM spectrum sensing and multi-antenna based full-duplex sensing. (ii) Address the contention issue in wideband fragmented spectrum sharing with low collision probabilities and low overhead. A spectrum arbitration mechanism is proposed, enabled by a parallel bitwise signaling scheme and a novel compound packet preamble design. (iii) Design a light-weight in-band mechanism that achieves fast synchronization and spectrum agreement, so as to overcome the substantial control channel overhead for spectrum agreement under high spectrum dynamics. The success of the proposed research will enhance radio spectrum sharing, and inspire standardization bodies to incorporate the proposed new protocol primitives for much higher performance. A continuous effort will be made to integrate the proposed research to education program, to mentor undergraduate researchers, and recruit women and minority students.