SpecEES: A spectrally-dense 650-GHz photonic wireless backhaul via secure network coding

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

Wireless communications and networks have experienced exponential growth in data rates and traffic over the past decade, driven by the ever-increasing density of mobile devices, multimedia services and data requirements. The resulting electromagnetic spectrum below 60-GHz has become extremely overcrowded, even with advanced spectrum-efficient modulation formats and spatially diverse multiple-input multiple-output (MIMO) techniques. At present, the sub-millimeter-wave (sub-mm-Wave) electromagnetic spectrum between 300 GHz and 850 GHz is largely unassigned and provides a unique opportunity for more efficient utilization. This will avoid further crowding the currently heavily used spectrum and significantly enhance data rates to tens of Gb/s. This project seeks to demonstrate such a fundamentally new platform towards spectral-efficient and energy-efficient wireless communications with embedded security. Due to the inherent atmospheric attenuation, the sub-mm-Wave communication distance has been limited to within 50 m. Thus, this project proposes network configurations of sub-mm-Wave point-to-point links to enable secured spatial coverage over longer distances and larger areas. There are two distinct differences of the sub-mm-Wave links compared to traditional wireless networks: the directivity of the sub-mm-Wave links and the possibility for a transmitter to connect to multiple receivers through adaptive electronic beam-steering and beam-forming. The beam-forming with narrow beam-width removes broadcasting and avoids interference, enabling much simpler network operation to approach the theoretical upper limits of network information capacity. The project seeks to demonstrate the modular sub-mm-Wave link hardware to achieve the above goal. The proposed research will be complemented with an integrated education and outreach program. This includes diversity recruitment, mentoring and retention, hands-on curriculum development, minority high-school and undergraduate training, and public outreach. The cross-layer scientific and education provides a new platform at the interface of hardware, software, and networks in next-generation wireless communication networks. This project will develop a spectrally dense, high-data-rate, 650-GHz photonic wireless communications platform in a diamond mesh network, while explicitly addressing network security and energy efficiency in the architecture. The collaborative research spans across the physical layer, the network layer, and the software layer, addressing cross-layer issues in the fundamental architecture. The proposed research consists of three thrust areas. In Thrust I, the project will examine a modular photonic sub-mm-Wave link, based on a chip-scale photomixer driven by an optical frequency comb recently developed by the team. This enables high-power spectrally dense, 80 Gb/s sub-mm-Wave transmission. In Thrust II, the project will examine a photonic sub-mm-Wave 80 Gb/s testbed, implemented with an adaptive smart antenna array. Beam-steering and beam-forming will enable simultaneously a directional line-of-sight (LoS) link and a non-line-of-sight (NLoS) link, with the former establishing a spectrally efficient channel with less inter-symbol and inter-channel interference. The latter mitigates medium non-idealities such as interference, shadowing, and multi-path effects. In Thrust III, the project will study the capacity of sub-mm-Wave communication networks and explore the design of near-optimal efficient and secure algorithms. Enabled by the intrinsic directivity and beam-forming capabilities of our sub-mm-Wave link, the project will advance the possibility of unconditional security in the wireless backhaul network through physical layer security algorithms. 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.