Millimeter-wave interconnects for intra- and inter-chip transmission and beam steering in NoC-based multi-chip systems

The primary objective of this work is to investigate the communication capabilities of short-range millimeter-wave (mm-wave) communication among Network-on-Chip (NoC) based multi-core processors integrated on a substrate board. To address the demand for high-performance multi-chip computing systems, the present work studies the transmission coefficients between the on-chip antennas system for both intra- and inter-chip communication. It addresses techniques for enhancing transmission by using antenna arrays for beamforming. It also explores new and creative solutions to minimize the adverse effects of silicon on electromagnetic wave propagation using artificial magnetic conductors (AMC). The following summarizes the work performed and future work. Intra- and inter-chip transmission between wireless interconnects implemented as antennas on-chip (AoC), in a wire-bonded chip package are studied 30GHz and 60 GHz. The simulations are performed in ANSYS HFSS, which is based on the finite element method (FEM), to study the transmission and to analyze the electric field distribution. Simulation results have been validated with fabricated antennas at 30 GHz arranged in different orientations on silicon dies that can communicate with inter-chip transmission coefficients ranging from -45dB to -60dB while sustaining bandwidths up to 7GHz. The fabricated antennas show a shift in the resonant frequency to 25GHz. This shift is attributed to the Ground-Signal-Ground (GSG) probes used for measurement and to the Short-Open-Load (SOLT) calibration which has anomalies at millimeter-wave frequencies. Using measurements, a large-scale log-normal channel model is derived which can be used for system-level architecture design. Further, at 60 GHz densely packed multilayer copper wires in NoCs have been modeled to study their impact on the wireless transmission between antennas for both intra- and inter-chip links and are shown to be equivalent to copper sheets. It is seen that the antenna radiation efficiency reduces in the presence of these densely packed wires placed close to the antenna elements. Using this model, the reduction of inter-chip transmission is seen to be about 20dB as compared to a system with no wires. Lastly, the transmission characteristics of the antennas resonating at 60GHz in a flip-chip packaging environment are also presented

Location prediction and trajectory optimization in multi-UAV application missions

Unmanned aerial vehicles (a.k.a. drones) have a wide range of applications in e.g., aerial surveillance, mapping, imaging, monitoring, maritime operations, parcel delivery, and disaster response management. Their operations require reliable networking environments and location-based services in air-to-air links with cooperative drones, or air-to-ground links in concert with ground control stations. When equipped with high-resolution video cameras or sensors to gain environmental situation awareness through object detection/tracking, precise location predictions of individual or groups of drones at any instant possible is critical for continuous guidance. The location predictions then can be used in trajectory optimization for achieving efficient operations (i.e., through effective resource utilization in terms of energy or network bandwidth consumption) and safe operations (i.e., through avoidance of obstacles or sudden landing) within application missions. In this thesis, we explain a diverse set of techniques involved in drone location prediction, position and velocity estimation and trajectory optimization involving: (i) Kalman Filtering techniques, and (ii) Machine Learning models such as reinforcement learning and deep-reinforcement learning. These techniques facilitate the drones to follow intelligent paths and establish optimal trajectories while carrying out successful application missions under given resource and network constraints. We detail the techniques using two scenarios. The first scenario involves location prediction based intelligent packet transfer between drones in a disaster response scenario using the various Kalman Filtering techniques. The second scenario involves a learning-based trajectory optimization that uses various reinforcement learning models for maintaining high video resolution and effective network performance in a civil application scenario such as aerial monitoring of persons/objects. We conclude with a list of open challenges and future works for intelligent path planning of drones using location prediction and trajectory optimization techniques.Includes bibliographical references

Wireless Interconnects for Intra-chip & Inter-chip Transmission

With the emergence of Internet of Things and information revolution, the demand of high performance computing systems is increasing. The copper interconnects inside the computing chips have evolved into a sophisticated network of interconnects known as Network on Chip (NoC) comprising of routers, switches, repeaters, just like computer networks. When network on chip is implemented on a large scale like in Multicore Multichip (MCMC) systems for High Performance Computing (HPC) systems, length of interconnects increases and so are the problems like power dissipation, interconnect delays, clock synchronization and electrical noise. In this thesis, wireless interconnects are chosen as the substitute for wired copper interconnects. Wireless interconnects offer easy integration with CMOS fabrication and chip packaging. Using wireless interconnects working at unlicensed mm-wave band (57-64GHz), high data rate of Gbps can be achieved. This thesis presents study of transmission between zigzag antennas as wireless interconnects for Multichip multicores (MCMC) systems and 3D IC. For MCMC systems, a four-chips 16-cores model is analyzed with only four wireless interconnects in three configurations with different antenna orientations and locations. Return loss and transmission coefficients are simulated in ANSYS HFSS. Moreover, wireless interconnects are designed, fabricated and tested on a 6’’ silicon wafer with resistivity of 55Ω-cm using a basic standard CMOS process. Wireless interconnect are designed to work at 30GHz using ANSYS HFSS. The fabricated antennas are resonating around 20GHz with a return loss of less than -10dB. The transmission coefficients between antenna pair within a 20mm x 20mm silicon die is found to be varying between -45dB to -55dB. Furthermore, wireless interconnect approach is extended for 3D IC. Wireless interconnects are implemented as zigzag antenna. This thesis extends the work of analyzing the wireless interconnects in 3D IC with different configurations of antenna orientations and coolants. The return loss and transmission coefficients are simulated using ANSYS HFSS

Environmentally-Aware and Energy-Efficient Multi-Drone Coordination and Networking for Disaster Response

In a Disaster Response Management (DRM) Scenario, Communication and Coordination Are Limited, and Absence of Related Infrastructure Hinders Situational Awareness. Unmanned Aerial Vehicles (UAVs) or Drones Provide New Capabilities for DRM to Address These Barriers. However, There is a Dearth of Works that Address Multiple Heterogeneous Drones Collaboratively Working Together to Form a Flying Ad-Hoc Network (FANET) with Air-To-Air and Air-To-Ground Links that Are Impacted By: (I) Environmental Obstacles, (Ii) Wind, and (Iii) Limited Battery Capacities. in This Paper, We Present a Novel Environmentally-Aware and Energy-Efficient Multi-Drone Coordination and Networking Scheme that Features a Reinforcement Learning (RL) based Location Prediction Algorithm Coupled with a Packet Forwarding Algorithm for Drone-To-Ground Network Establishment. We Specifically Present Two Novel Drone Location-Based Solutions (I.e., Heuristic Greedy, and Learning-Based) in Our Packet Forwarding Approach to Support Application Requirements. These Requirements Involve Improving Connectivity (I.e., Optimize Packet Delivery Ratio and End-To-End Delay) Despite Environmental Obstacles, and Improving Efficiency (I.e., by Lower Energy Use and Time Consumption) Despite Energy Constraints. We Evaluate Our Scheme with State-Of-The-Art Networking Algorithms in a Trace-Based DRM FANET Simulation Testbed Featuring Rural and Metropolitan Areas. Results Show that Our Strategy overcomes Obstacles and Can Achieve 81-To-90% of Network Connectivity Performance Observed under No Obstacle Conditions. in the Presence of Obstacles, Our Scheme Improves the Network Connectivity Performance by 14-To-38% While Also Providing 23-To-54% of Energy Savings in Rural Areas; the Same in Metropolitan Areas Achieved an Average of 25% Gain When Compared with Baseline Obstacle Awareness Approaches with 15-To-76% of Energy Savings

Beam Steering for 3D Network on Chip with Embedded Micro Thermofluidic Cooling Channels

The present work uses phased antenna arrays to provide a dynamic reconfiguring of 3D Wireless-Network-on-a-Chip (WNoC) to respond to various demands for example, thermal emergencies. A novel 3D WNoC architecture with embedded micro fluidic layers addresses the interior heating. Zigzag antenna and log periodic antenna modeled at 60GHz in HFSS are configured as phased arrays for beam steering. Results are encouraging, with a good main beam in the plane of the chip

Conversion of a CNG Powered Auto Rickshaw to an Electric Rickshaw Designed for Indian Conditions

Three wheeler taxis, commonly known as auto rickshaw are a popular means of transport in developing countries. However, low efficiencies and poor maintenance are common (especially in India). This results in high fossil fuel consumption, and very high urban air pollution due to these vehicles. Electrification of auto-rickshaw, therefore, is a potential solution to reduce dependence on fossil fuels, and reduce environmental pollution. However, this conversion is not straightforward. In this work, we investigate some of the challenges of converting an existing combustion engine powered auto-rickshaw to an electric auto rickshaw (electric vehicle (EV)). The cost of conversion to EV and sufficient charge storage capacity for driving range are important factors in the viability of such a conversion. The solution developed here is a design for low total ownership cost for short-range transport. The factors that affect the total cost of ownership are local availability of components, performance efficiency, actual cost of conversion, and skills available with local technicians. These constraints move the most suitable configuration away from configurations that are more typical in the developed economies, such as Li-Ion Batteries and brush-less DC motors (BLDC) to more affordable and well-known technologies such as lead acid batteries and permanent magnet DC motors (PMDC). In this paper, the relative merits of various configurations of batteries, motors and power transmission systems are discussed. Design variables are optimized for a specific top speed and driving range via simulations. The design is evaluated by on-road testing of the modified vehicle. The design challenges are described and the safety aspects and concerns are highlighted. An over-the-life cost comparison of the electrification of the rickshaw with conventional engine powered rickshaws is also discussed.by Rounak Mehta, Preet Shah, Harsh Gupta, Prathamesh Bhat, Vaibhav Gandhi, Kimaya Kale, Madan Taldevkar, Akash Singh, Chinmay Ghoroi, Atul Bhargav and Amey Karni

The Advances, Challenges and Future Possibilities of Millimeter-Wave Chip-to-Chip Interconnections for Multi-Chip Systems

With aggressive scaling of device geometries, density of manufacturing faults is expected to increase. Therefore, yield of complex Multi-Processor Systems-on-Chips (MP-SoCs) will decrease due to higher probability of manufacturing defects especially, in dies with large area. Therefore, disintegration of large SoCs into smaller chips called chiplets will improve yield and cost of complex platform-based systems. This will also provide functional flexibility, modular scalability as well as the capability to integrate heterogeneous architectures and technologies in a single unit. However, with scaling of the number of chiplets in such a system, the shared resources in the system such as the interconnection fabric and memory modules will become performance bottlenecks. Additionally, the integration of heterogeneous chiplets operating at different frequencies and voltages can be challenging. State-of-the-art inter-chip communication requires power-hungry high-speed I/O circuits and data transfer over long wired traces on substrates. This increases energy consumption and latency while decreasing data bandwidth for chip-to-chip communication. In this paper, we explore the advances and the challenges of interconnecting a multi-chip system with millimeter-wave (mm-wave) wireless interconnects from a variety of perspectives spanning multiple aspects of the wireless interconnection design. Our discussion on the recent advances include aspects such as interconnection topology, physical layer, Medium Access Control (MAC) and routing protocols. We also present some potential paradigm-shifting applications as well as complementary technologies of wireless inter-chip communications