Robust and Traffic Aware Medium Access Control Mechanisms for Energy-Efficient mm-Wave Wireless Network-on-Chip Architectures

To cater to the performance/watt needs, processors with multiple processing cores on the same chip have become the de-facto design choice. In such multicore systems, Network-on-Chip (NoC) serves as a communication infrastructure for data transfer among the cores on the chip. However, conventional metallic interconnect based NoCs are constrained by their long multi-hop latencies and high power consumption, limiting the performance gain in these systems. Among, different alternatives, due to the CMOS compatibility and energy-efficiency, low-latency wireless interconnect operating in the millimeter wave (mm-wave) band is nearer term solution to this multi-hop communication problem. This has led to the recent exploration of millimeter-wave (mm-wave) wireless technologies in wireless NoC architectures (WiNoC). To realize the mm-wave wireless interconnect in a WiNoC, a wireless interface (WI) equipped with on-chip antenna and transceiver circuit operating at 60GHz frequency range is integrated to the ports of some NoC switches. The WIs are also equipped with a medium access control (MAC) mechanism that ensures a collision free and energy-efficient communication among the WIs located at different parts on the chip. However, due to shrinking feature size and complex integration in CMOS technology, high-density chips like multicore systems are prone to manufacturing defects and dynamic faults during chip operation. Such failures can result in permanently broken wireless links or cause the MAC to malfunction in a WiNoC. Consequently, the energy-efficient communication through the wireless medium will be compromised. Furthermore, the energy efficiency in the wireless channel access is also dependent on the traffic pattern of the applications running on the multicore systems. Due to the bursty and self-similar nature of the NoC traffic patterns, the traffic demand of the WIs can vary both spatially and temporally. Ineffective management of such traffic variation of the WIs, limits the performance and energy benefits of the novel mm-wave interconnect technology. Hence, to utilize the full potential of the novel mm-wave interconnect technology in WiNoCs, design of a simple, fair, robust, and efficient MAC is of paramount importance. The main goal of this dissertation is to propose the design principles for robust and traffic-aware MAC mechanisms to provide high bandwidth, low latency, and energy-efficient data communication in mm-wave WiNoCs. The proposed solution has two parts. In the first part, we propose the cross-layer design methodology of robust WiNoC architecture that can minimize the effect of permanent failure of the wireless links and recover from transient failures caused by single event upsets (SEU). Then, in the second part, we present a traffic-aware MAC mechanism that can adjust the transmission slots of the WIs based on the traffic demand of the WIs. The proposed MAC is also robust against the failure of the wireless access mechanism. Finally, as future research directions, this idea of traffic awareness is extended throughout the whole NoC by enabling adaptiveness in both wired and wireless interconnection fabric

Devices for safety-critical molecular programmed systems

The behavior of matter at the molecular level can be programmed to create nanoscale molecular components that accomplish desired tasks. Many molecular components are developed with intended uses that are safety-critical, such as medical applications. Ensuring the correctness and fault tolerance of such devices is paramount. Techniques to develop robustly correct programs have been widely studied in software systems and many devices have been constructed to aid in the safe operation of systems. We seek to demonstrate the effectiveness of software and safety engineering techniques in the molecular programming domain. In this thesis, we present the design of five new devices to aid in the development of safetycritical molecular programmed systems. We introduce a Runtime Fault Detection device (RFD) to robustly detect faults and initiate recovery actions in response to a failed system. We present the Concentration Monitor, a device that can detect changes, major and minor, in concentrations in real-time and demonstrate its utility. We also describe methods for constructing chemical reaction networks that can robustly simulate any combinational logic gate. Finally, we present two devices to log the state of a molecular program, where the first device logs a state upon receiving a request, and the second device ensures that the current state meets a defined validity property before allowing a log to be taken. All devices have been formally verified using model checking, simulations, or formal proof techniques. The methods used to construct and verify these devices can be adapted to the design of future molecular systems to assist in ensuring their correctness

FDMA Enabled Phase-based Wireless Network-on-Chip using Graphene-based THz-band Antennas

The future growth in System-on-chip design is moving in the direction of multicore systems. Design of efficient interconnects between cores are crucial for improving the performance of a multicore processor. Such trends are seen due to the benefits the multicore systems provide in terms of power reduction and scalability. Network-on-chips (NoC) are viewed as an emerging solution in the design of interconnects in multicore systems. However, Traditional Network-on-chip architectures are no longer able to satisfy the performance requirements due to long distance communication over multi-hop wireline paths. Multi-hop communication leads to higher energy consumption, increase in latency and reduction in bandwidth. Research in recent years has explored emerging technologies such as 3D integration, photonic and radio frequency based Network-on-chips. The use of wireless interconnects using mm-wave antennas are able to alleviate the performance issues in a wireline interconnect system. However, to satisfy the increasing demand for higher bandwidth and lower energy consumption, Wireless Network-on-Chip enabled with high speed direct links operating in THz band between distant cores is desired. Recent research has brought to light highly efficient graphene-based antennas operating in THz band. These antennas can provide high data rate and are found to consume less power with low area overheads. In this thesis, an innovative approach using novel devices based on graphene structures is proposed to provide a high-performance on-chip interconnection. This novel approach combines the regular NoC structure with the proposed wireless infrastructure to exploit the performance benefits. An architecture with wireless interfaces on every core is explored in this work. Simultaneous multiple communications in a network can be achieved by adopting Frequency Division Multiple access (FDMA). However, in a system where all cores are equipped with a wireless interface, FDMA requires more number of frequency bands. This becomes difficult to achieve as the system scales and the number of cores increase. Therefore, a FDMA protocol along with a 4-phased repetitive multi-band architecture is envisioned in this work. The phase-based protocol allows multiple wireless links to be active at a time, the phase-based protocol along with the FDMA protocol provides a reliable data transfer between cores with lesser number of frequency bands. In this thesis, an architecture with a combination of FDMA and phase-based protocol using point-to-point graphene-based wireless links is proposed. The proposed architecture is also extended for a multichip system. With cycle accurate system-level simulations, it is shown that the proposed architecture provides huge gains in performance and energy-efficiency in data transfer both in NoC based multicore and multichip systems

Enabling Cyber-Physical Communication in 5G Cellular Networks: Challenges, Solutions and Applications

Cyber-physical systems (CPS) are expected to revolutionize the world through a myriad of applications in health-care, disaster event applications, environmental management, vehicular networks, industrial automation, and so on. The continuous explosive increase in wireless data traffic, driven by the global rise of smartphones, tablets, video streaming, and online social networking applications along with the anticipated wide massive sensors deployments, will create a set of challenges to network providers, especially that future fifth generation (5G) cellular networks will help facilitate the enabling of CPS communications over current network infrastructure. In this dissertation, we first provide an overview of CPS taxonomy along with its challenges from energy efficiency, security, and reliability. Then we present different tractable analytical solutions through different 5G technologies, such as device-to-device (D2D) communications, cell shrinking and offloading, in order to enable CPS traffic over cellular networks. These technologies also provide CPS with several benefits such as ubiquitous coverage, global connectivity, reliability and security. By tuning specific network parameters, the proposed solutions allow the achievement of balance and fairness in spectral efficiency and minimum achievable throughout among cellular users and CPS devices. To conclude, we present a CPS mobile-health application as a case study where security of the medical health cyber-physical space is discussed in details

Terahertz Communications and Sensing for 6G and Beyond: A Comprehensive View

The next-generation wireless technologies, commonly referred to as the sixth generation (6G), are envisioned to support extreme communications capacity and in particular disruption in the network sensing capabilities. The terahertz (THz) band is one potential enabler for those due to the enormous unused frequency bands and the high spatial resolution enabled by both short wavelengths and bandwidths. Different from earlier surveys, this paper presents a comprehensive treatment and technology survey on THz communications and sensing in terms of the advantages, applications, propagation characterization, channel modeling, measurement campaigns, antennas, transceiver devices, beamforming, networking, the integration of communications and sensing, and experimental testbeds. Starting from the motivation and use cases, we survey the development and historical perspective of THz communications and sensing with the anticipated 6G requirements. We explore the radio propagation, channel modeling, and measurements for THz band. The transceiver requirements, architectures, technological challenges, and approaches together with means to compensate for the high propagation losses by appropriate antenna and beamforming solutions. We survey also several system technologies required by or beneficial for THz systems. The synergistic design of sensing and communications is explored with depth. Practical trials, demonstrations, and experiments are also summarized. The paper gives a holistic view of the current state of the art and highlights the issues and challenges that are open for further research towards 6G.Comment: 55 pages, 10 figures, 8 tables, submitted to IEEE Communications Surveys & Tutorial

Channel Modelling of Blood Capillary-based Molecular Communication

Molecular communication (MC) is a new and promising interdisciplinary bio-inspired communication paradigm, which uses molecules as information carriers. Differing from traditional communication, MC is proposed as a feasible solution for nanoscale communication with the help of biological scenarios to overcome the communication limitations. Meanwhile, it is inspired by intracellular and intercellular communication, which involves exchange of information through the transmission, propagation, and reception of molecules. Blood capillaries, extensively distributed in the human body and mutually connected with tissues, are potentially applied to MC, which is the major motivation of this thesis. The focus of this PhD thesis is on the channel modelling of blood capillaries or blood vessels. The objectives of the research are to provide solutions to the modelling of blood capillary-based MC from a communication engineering and information theory perspective. The relationship of the biological scenario in blood capillaries to a communication system is studied. After demonstrating the mapping from biological phenomenon to emission, propagation and reception processes, system models are established. There are three models of blood capillaries behind different biological scenarios. Firstly, the thesis establishes a basic model of vesicle release, vesicle diffusion through blood capillary and ligand reception processes within the endocrine phenomenon. Moreover, differing from previous research in macroscopic Fick's diffusion, this work involves microscopic Langevin diffusion to describe the propagation process with a frequency domain method being proposed to calculate the information-theoretical performance channel capacity. Secondly, a much more realistic blood capillary model with blood flow drift which matches a laminar flow regime is presented, where a generalised Langevin equation is used to model the drift force exerted by blood flow. Finally, the thesis establishes a single input and multiple output MC model with hierarchical levels of Y-shaped bifurcation of blood capillaries, then BER, SNR, and channel capacity performance are analysed

Mathematical Modeling and Simulation in Mechanics and Dynamic Systems

The present book contains the 16 papers accepted and published in the Special Issue “Mathematical Modeling and Simulation in Mechanics and Dynamic Systems” of the MDPI “Mathematics” journal, which cover a wide range of topics connected to the theory and applications of Modeling and Simulation of Dynamic Systems in different field. These topics include, among others, methods to model and simulate mechanical system in real engineering. It is hopped that the book will find interest and be useful for those working in the area of Modeling and Simulation of the Dynamic Systems, as well as for those with the proper mathematical background and willing to become familiar with recent advances in Dynamic Systems, which has nowadays entered almost all sectors of human life and activity