Kenneth Tong

Hybrid wire-surface wave architecture for one-to-many communication in networks-on-chip

Network-on-chip (NoC) is a communication paradigm that has emerged to tackle different on-chip challenges and has satisfied different demands in terms of high performance and economical interconnect implementation. However, merely metal based NoC pursuit offers limited scalability with the relentless technology scaling, especially in one-to-many (1-to-M) communication. To meet the scalability demand, this paper proposes a new hybrid architecture empowered by both metal interconnects and Zenneck surface wave interconnects (SWI). This architecture, in conjunction with newly proposed routing and global arbitration schemes, avoids overloading the NoC and alleviates traffic hotspots compared to the trend of handling 1-to-M traffic as unicast. This work addresses the system level challenges for intra chip multicasting. Evaluation results, based on a cycle-accurate simulation and hardware description, demonstrate the effectiveness of the proposed architecture in terms of power reduction ratio of 4 to 12X and average delay reduction of 25X or more, compared to a regular NoC. These results are achieved with negligible hardware overheads.

Surface wave communication system for on-chip and off-chip interconnects

Network-on-chip (NoC) is a communication paradigm that has emerged to tackle different on-chip challenges and satisfy different demands in terms of high performance and economical interconnect implementation. However, merely metal based interconnect pursuit offers limited scalability with the relentless technology scaling. To meet the scalability demand, this paper proposes a new hybrid interconnect fabric empowered by metal interconnect NoC and Zenneck surface Waves Interconnect (SWI) technology. Our initial results show a considerable power reduction (9 to 17%) and performance improvement (35%) of the proposed hybrid architecture compared to regular NoC. These results are achieved over relatively small hardware and area overhead (2.29% of die). This paper explores promising potentials of SWI for future System-on-Chip (SoC) global communication.

Novel Hybrid Wired-Wireless Network-on-Chip Architectures: Transducer and Communication Fabric Design

Existing wireless communication interface of Hybrid Wired-Wireless Network-on-Chip (WiNoC) has 3-dimensional free space signal radiation which has high power dissipation and drastically affects the received signal strength. In this paper, we propose a CMOS based 2-dimensional (2-D) waveguide communication fabric that is able to match the channel reliability of traditional wired NoCs as the wireless communication fabric. Our experimental results demonstrate that, the proposed communication fabric can achieve a 5dB operational bandwidth of about 60GHz around the center frequency (60GHz). Compared to existing WiNoCs, the proposed communication fabric can improve the reliability of WiNoCs with average gains of 21.4%, 13.8% and 10.6% performance efficiencies in terms of maximum sustainable load, throughput and delay, respectively.

On the Design of Reliable Hybrid Wired-Wireless Network-on-Chip Architectures

With the ever increase in transistor density over technology scaling, energy and performance aware hybrid wireless Network-on-Chip (WiNoC) has emerged as an alternative solution to the slow conventional wireline NoC design for future System-on-Chip (SoC). However, combining wireless and wireline channels drastically reduces the total reliability of the communication fabric. Besides being lossy, existing feasible wireless solution for WiNoCs, which is in the form of millimeter wave (mm-Wave), relies on free space signal radiation which has high power dissipation with high degradation rate in the signal strength per transmission distance. Alternatively, low power wireless communication fabric in the form of surface wave has been proposed for on-chip communication. With the right design considerations, the reliability and performance benefits of the surface wave channel could be extended. In this paper, we propose a surface wave communication fabric for emerging WiNoCs that is able to match the channel reliability of traditional wireline NoCs. Here, a carefully designed transducer and commercially available thin metal conductor coated with a low cost dielectric material are employed to general surface wave signal to improve the wireless signal transmission gain. Our experimental results demonstrate that, the proposed communication fabric can achieve a 5dB operational bandwidth of about 60GHz around the center frequency (60GHz). By improving the transmission reliability of wireless layer, the proposed communication fabric can improve maximum sustainable load of NoCs by an average of 20.9% and 133.3% compared to existing WiNoCs and wireline NoCs, respectively.

Large scale antenna arrays with increasing antennas in limited physical space

Large Scale multiple input multiple output (MIMO) systems have recently emerged as a promising technology for 5G communications. While they have been shown to offer significant performance benefits in theoretical studies, the large scale MIMO transmitters will have to be deployed in the limited physical space of todays base stations (BSs). Accordingly, this paper examines effects of deploying increasing numbers of antennas in fxed physical space, by reducing the antenna spacing. We focus on the resulting performance of large-scale MIMO transmitters using low complexity closed form precoding techniques. In particular, we investigate the combined effect of reducing the distance between the antenna elements with increasing the number of elements in a fxed transmitter space. This gives rise to two contradicting phenomena: the reduction of spatial diversity due to reducing the separation between antennas and the increase in transmit diversity by increasing the number of elements. To quantify this tradeoff, we investigate densely deployed uniform antenna arrays modelled by detailed electromagnetic simulation. Our results show the somewhat surprising result that, by reducing the separations between the antennas to signifcantly less than the transmit wavelength to ft more antennas, the resulting system performance improves.

Synthetic Aperture Radar Signature for Oil Sands Exploration

Common soil and oil sand have different electromagnetic wave reflectivity. In this paper, we explore the possibility to use Synthetic Aperture Radar (SAR) technique to identify and distinguish between three types of soil. The results from the electromagnetic wave models provide a comparison of backscattering behavior between common soil and oil sand terrain. Moreover it enables the development of a radar signature database that can provide useful reference for the design of an optimum SAR system for oil sand resource discovery.

Modeling Electromagnetic Reflectivity of Agbabu Oil Sand from Hyperspectral Infrared Reflectance Spectra and Dielectric Properties at L-, C- and X-Band Frequencies

In this paper remote identification of oil sand reservoirs from synthetic aperture radar (SAR) is enhanced by accurate modeling of the electromagnetic (EM) reflectivity of Agbabu oil sands. This is demonstrated using a novel combination of hyperspectral reflectance spectra and dielectric permittivity measurements with computer simulation tools. Infrared spectra (4cm-1 resolution) were obtained that covered the near-infrared (NIR) and mid-infrared (MIR) regions (2.5 - 25μm) to verify the presence of bitumen and sand in Agbabu oil sands. Thereafter the dielectric properties at L-, C- and X-band frequencies were determined using coaxial probe measurements to provide previously non-existent information on the electrical properties of oil sand terrain. This data was used to investigate the EM reflectivity of Agbabu oil sand with EM scattering models developed using computer simulation tools for L-, C- and X-band and geometry θi = 20° to 90°.

Development of a hybrid microwave-optical tissue oxygenation probe to measure thermal response in the deep tissue.

The design of a new non-invasive hybrid microwave-optical tissue oxygenation probe is presented, which consists of a microwave biocompatible antenna and an optical probe. The microwave antenna is capable of inducing localised heat in the deep tissue, causing tissue blood flow and therefore tissue oxygenation to change. These changes or thermal responses are measured by the optical probe using near-infrared spectroscopy. Thermal responses provide important information on thermoregulation in human tissue. The first prototype of the biocompatible antenna was developed and placed on the human calf for in vivo experiments. The measured results include oxy-, deoxy- and total haemoglobin concentration changes (ΔHbO2/ΔHHb/ΔHbT), tissue oxygenation index and the normalised tissue haemoglobin index for two human subjects. Both ΔHbO2 and ΔHbT show an increase during 5 min of microwave exposure. The thermal response, defined as the ratio of the increase in ΔHbT to the time duration, is 7.7 μM/s for subject 1 (fat thickness = 6.8 mm) and 18.9 μM/s for subject 2 (fat thickness = 5.0 mm), which may be influenced by the fat thicknesses. In both subjects, ΔHbO2 and ΔHbT continued to increase for approximately another 70 s after the microwave antenna was switched off.

Electromagnetic Characterisation of Terrain for Unconventional Petroleum Exploration

A method to characterize the electromagnetic (EM) signature of barefaced terrain using 3D computer electromagnetic models (CEM) for radar applications is presented. Five barefaced terrain types with different electrical, physical and chemical properties were investigated. They include both homogeneous and heterogeneous terrain types particularly beach sand, gravel and pebble acquired locally and oil sands from Nigeria. The approach develops CEMs using reflectance spectroscopy and dielectric permittivity data. First geochemical signatures were determined using reflectance spectroscopy in the Near Infrared region while dielectric properties were experimentally determined at L-, C- and X-band for multi-frequency radar. Both viscous and hard oil sand indicated resonance effects in the upper C-band. The results provide new information on the complex electrical permittivity ε*(co) and loss tangent, tan ö. Finally a laboratory based approach to measure the relationship between sensor configuration and terrain backscatter for 0.013m3 of terrain samples using microwave measurement techniques in an anechoic chamber is outlined.

Development of a Hybrid Microwave-Optical Thermoregulation Monitor for the Muscle

This paper presents the latest development of the hybrid microwave-optical thermoregulation monitor for the muscle. It is capable of warming the muscle and measuring the subsequent blood volume changes, using a novel microwave applicator with integrated optical probes. The challenge is to measure the thermoregulation response in deep tissue while minimizing any effect from the skin layer. We have introduced a skin cooling device, an additional integrated optical Laser Doppler flow monitoring probe and a temperature sensor to measure skin blood flow and temperature, respectively. The result shows that skin cooling is essential to minimize skin flow changes during microwave warming. The hybrid probe was placed on a human thigh to measure oxy/deoxy/total haemoglobin concentration changes (ΔHbO₂/ΔHHb/ΔHbT), skin flux and temperature upon microwave warming. Without skin cooling, the skin temperature was elevated by 4 °C and both ΔHbO₂/ΔHbT and skin flux increased, showing microwave warming occurring in both the skin and muscle. With skin cooling, the skin temperature was kept relatively constant. While ΔHbO₂/ΔHbT increased, the skin flux was relatively stable, showing a preferential microwave warming in the muscle, rather than the skin.