High Bandwidth Communication Channels Research Articles

A 16-nm 784-Core Digital Signal Processor Array, Assembled as a 2 × 2 Dielet With 10-μm Pitch Interdielet I/O for Runtime Multiprogram Reconfiguration

Modern applications require hardware accelerators to maintain energy efficiency while satisfying the increasing computation requirements. However, with evolving standards and rapidly changing algorithmic complexity as well as rising design costs at advanced technology nodes, the iterative development of inflexible accelerators for such applications becomes ineffective. The reconfigurable architectures can provide a higher throughput and the required flexibility, but with substantial energy and area efficiency overhead relative to the accelerators. We develop a domain-specific, energy- and area-efficient (within 2× - 10× of accelerators) multiprogram runtime reconfigurable accelerator called the universal digital signal processor (UDSP). The design maximizes generality and resource utilization for signal processing and linear algebra with minimal area and energy penalty. The statistics-driven multilayer network minimizes the network delay and consists of an optimized switchbox design that maximizes the connectivity per hardware cost. The multilayered interconnect network is linearly scalable with the number of processing elements and allows for intradielet and multidielet scaling. The network features’ deterministic routing and timing for fast program compile and its translation and rotation symmetries allow for hardware resource reallocation. Multidielet scaling is enabled by energy-efficient, high-bandwidth, and high-density interdielet communication channels that seamlessly extend the intradielet routing network across the dielet boundaries using 10- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> fine-pitch silicon interconnect fabric (Si-IF) interposer. A 2 × 2 multidielet UDSP on Si-IF can achieve a peak energy efficiency of 785 GMACs/J at 0.42 V and 315 MHz. The interdielet communication channel, SNR-10, provides a shoreline bandwidth density of 297 Gb/s/mm at 1.1 Gb/s/pin at 0.8 V and nominal energy efficiency of 0.38 pJ/bit.

Transient Wavelet Energy-Based Protection Scheme for Inverter-Dominated Microgrid

When faults occur in the microgrids, high frequency transients will be superimposed on the system currents and voltages. The magnitude of those transients will attenuate as it encounters the discontinuity points in the network such as busbars, or any other impedance discontinuity points. This phenomenon can also be quantified by wavelet energy, which provides a useful tool to detect faults and locate the faulted feeder in the microgrid. In this paper, a novel protection scheme based on the transient wavelet energy of the superimposed current extracted by the Maximal Overlap Discrete Wavelet Transform (MODWT) algorithm is developed to detect faults and locate the faulted feeder in microgrids. Compared with existing protection schemes, the proposed protection scheme has the advantage of being largely immune to the changes in system fault level, fault types and positions, microgrid operating status and the control strategies deployed on the inverters, while presenting much lower requirement on the sampling frequency (10 kHz) compared with travelling wave-based methods. Unlike the conventional differential protection, the proposed scheme does not require synchronized measurement or high bandwidth communication channels, and thus, it can be considered as an economical and promising solution for microgrids.

A Multilevel Distributed Hybrid Control Scheme for Islanded DC Microgrids

This paper proposes a multilevel hybrid control scheme, including grid control and node control, for an islanded 48-V solar photovoltaic-based low voltage dc microgrid that aims to overcome the drawbacks of centralized and decentralized control schemes. The analyzed microgrid includes a 35-kW rooftop solar system as the main power source at bus-1 with battery storage, 5-kW hybrid energy storage system (Vanadium Redox flow battery with super capacitor) at bus-2, and variable loads such as electrical vehicles at bus-3. In the case of a central failure, the proposed hybrid control scheme is capable of seamlessly switching between high bandwidth communication and low bandwidth communication channels of communications to implement a distributed control scheme. The central supervisory controller is responsible for updation of grid characteristics and sending/receiving information to/from local node controllers, which are responsible for bus voltage regulation and energy management. The control hierarchy features optimized and safe operation (charge and discharge) of storage devices in dc microgrids. The paper also demonstrates the application of battery-supercapacitor systems to absorb system transients during load changes. The simulation showcases the continuous flow of information and decision processes via each level of control while simultaneously taking into consideration the constraints of each subsystem. The scheme has been simulated in MATLAB/Simulink environment for various case studies to evaluate system robustness. Further, the proposed scheme has been tested experimentally with its prototype and its results are explored.

Cooperative Regulation of Imbalances in Three-Phase Four-Wire Microgrids Using Single-Phase Droop Control and Secondary Control Algorithms

Collaborative control of power converters operating in microgrids with unbalanced single-phase loads is difficult to achieve, considering that the voltages and currents have positive-, negative-, and zero-sequence components. In this paper, a new control scheme for collaborative control of four-leg microgrids is proposed. The main advantage of the proposed methodology is simplicity, because the sharing of the powers produced by the positive-, negative-, and zero-sequence voltage and currents is simple to achieve using the easy to implement and well-known droop control algorithms, i.e., as those based on $P$ – $\omega$ and $Q$ – $v$ droop control. The proposed droop algorithms do not require high bandwidth communication channels and the application of virtual impedances, whose design usually demands extensive simulation work, is not required. Three secondary control systems are also analyzed, discussed, and implemented in this paper to regulate the frequency, voltage, and phase at the point of common coupling (PCC), to achieve a balanced 50-Hz three-phase voltage supply in the PCC during steady-state operation. For these secondary control systems, single-phase phase-locked loop based on quadrature signal generators are implemented. Small signal modeling and design are discussed in this paper. A microgrid prototype of $\approx$ 5 kW, implemented using two power converters of 3 kW (each), is used to experimentally validate the proposed algorithms.

Distributed Load Balancing for the Adaptive Video Streaming Using CDN with Ring System of Server Consolidation by Circulant Topology

This article is devoted to development of an automated service for media content delivery network when adaptive online streaming on the Internet. This allows automatically adjusting of the amount of transmitted data per unit of time (bitrate) with changing in quality of requested media content accordingly. Consequently, the quality will be underestimated to those using low-bandwidth data channels, and vice versa, the content will be provided with highest possible quality for those connected to high-bandwidth communication channels. In this process, a user does not take any part: client video player itself determines which bitrate will optimally display the content to a particular user in order to avoid video buffering with the highest possible quality ensured. Switching between bitrates can occur continuously with a decrease/increase according to changes in quality of currently available bandwidth. In addition to adaptive video broadcast, the developed service allows transcoding of video streams on the fly. After receiving of input RTSP/RTMP stream, the network converts it to RTMP/HLS multi-bitrate, resulting in the generation of video streams of different quality which can be supported by both mobile devices and personal computers.

Source Coding Options to Improve HEVC Video Streaming in Vehicular Networks

Video delivery in Vehicular Ad-hoc NETworks has a great number of applications. However, multimedia streaming over this kind of networks is a very challenging issue because (a) it is one of the most resource-demanding applications; (b) it requires high bandwidth communication channels; (c) it shows moderate to high node mobility patterns and (d) it is common to find high communication interference levels that derive in moderate to high loss rates. In this work, we present a simulation framework based on OMNeT++ network simulator, Veins framework, and the SUMO mobility traffic simulator that aims to study, evaluate, and also design new techniques to improve video delivery over Vehicular Ad-hoc NETworks. Using the proposed simulation framework we will study different coding options, available at the HEVC video encoder, that will help to improve the perceived video quality in this kind of networks. The experimental results show that packet losses significantly reduce video quality when low interference levels are found in an urban scenario. By using different INTRA refresh options combined with appropriate tile coding, we will improve the resilience of HEVC video delivery services in VANET urban scenarios.

Introduction to the Special Issue on Signal Processing for Millimeter Wave Wireless Communications

The eleven papers in this special section focus signal processing for millimeter wave (mmWave) wireless communications. These mmWave frequencies are defining a new era of wireless communication. The mmWave band relieves spectral gridlock at lower frequencies by offering much higher bandwidth communication channels than presently used in commercial wireless systems. The next generation of wireless local area networks is exploiting the mmWave unlicensed band at 60 GHz to provide multigigabit-per-second data rates. There is also growing interest in using mmWave licensed spectrum for 5G cellular systems. MmWave communication could also provide important benefits in other application scenarios like wearable networks, vehicular communications, or autonomous robots. The potential for mmWave is immense. Signal processing is critical for enabling the next generation of mmWave communication. Because of the wide bandwidth, overall complexity and mixed signal power consumption are significant concerns. The papers in this section bring together contributions from researchers and practitioners in the area of signal processing for wireless communications with an emphasis on communication at millimeter wave frequencies. I

MIMO Precoding and Combining Solutions for Millimeter-Wave Systems

Millimeter-wave communication is one way to alleviate the spectrum gridlock at lower frequencies while simultaneously providing high-bandwidth communication channels. MmWave makes use of MIMO through large antenna arrays at both the base station and the mobile station to provide sufficient received signal power. This article explains how beamforming and precoding are different in MIMO mmWave systems than in their lower-frequency counterparts, due to different hardware constraints and channel characteristics. Two potential architectures are reviewed: hybrid analog/digital precoding/combining and combining with low-resolution analog- to-digital converters. The potential gains and design challenges for these strategies are discussed, and future research directions are highlighted.

Coverage and capacity of millimeter-wave cellular networks

The millimeter-wave (mmWave) band offers the potential for high-bandwidth communication channels in cellular networks. It is not clear, however, whether both high data rates and coverage in terms of signal-to-noise-plus-interference ratio can be achieved in interference-limited mmWave cellular networks due to the differences in propagation conditions and antenna topologies. This article shows that dense mmWave networks can achieve both higher data rates and comparable coverage relative to conventional microwave networks. Sum rate gains can be achieved using more advanced beamforming techniques that allow multiuser transmission. The insights are derived using a new theoretical network model that incorporates key characteristics of mmWave networks.

Advance lightpath reservation for WDM networks with dynamic traffic

Advance reservation is a topic that is rarely discussed within the domain of wavelength division multiplexed (WDM) networks. However, for many emerging applications in the telecommunication and/or grid computing industries, a demand for a high bandwidth communication channel as well as a guarantee on resource availability certainly exists. Such applications include: remote surgery, remote experimentation with teleobservation capabilities, teleconferencing, and bulk transfers. We present what we believe to be a new model for reserving advance lightpath requests in a centralized system. This model attempts to 'migrate,' i.e., move previously reserved lightpaths to candidate wavelengths in order to lower the system's blocking probability. We have tailored different lightpath migration algorithms to address two specific network objectives: (1) minimize the number of hops a new request traverses after migration, and (2) minimize the number of migrated lightpaths.

A flexible DSP-based network for real-time image-processing

This paper proposed a general purpose real-time image processing system based on a flexible DSP-based Network, which is implemented by a high bandwidth communication channel, links. The links is realized using FPGA and provides a bandwidth of 12. 8 Gbit/s. Using the links, The topologic of multi-DSP system can be changed online to meet the variabilities of the parallel algorithm of image processing. The system can be assembled with utmost tens of boards and maintain the high communication speed. Analysis of the system adaptivity to image processing is testified followed by actual results.

THESEUS—THE EVOLUTION OF A HYPERMEDIUM

The convergence of computer technology, multimedia, and high-bandwidth communication channels challenges our understanding of information technology. Processes of education, training, and entertainment, as well as provision of knowledge, can be envisaged as constituting a common environment of enhanced communication and interaction. Braiding together these disparate strands entails a novel appreciation of both knowledge itself and the learning process. The Theseus system is prototypical of such convergence, demonstrating how the idealist models of knowledge transfer and expertise that have dominated computer design and information systems may be replaced by an embodied model of knowledge and understanding as effective action. Realizing the imperatives for an enabling network system, Theseus allows the expression of personal views and subjective experience, while providing the means of constituting local, regional, and global domains of shared appreciation and understanding.

The 1988 CSCW: trip report

Computer-supported cooperative work (CSCW) is a new research field focused on the role of the computer in group work. On one hand it is technology-driven, motivated by such things as distributed computing, network file systems, electronic messaging, and high-bandwidth communication channels. On the other hand, it is socially-driven, motivated by studies of group interaction.