Reconfigurable Operation Research Articles

TOOLS OF C PROGRAM TRANSLATION FOR RECONFIGURABLE AND HYBRID COMPUTER SYSTEMS BASED ON FIELD-PROGRAMMABLE GATE ARRAYS

In this article, we consider the stages of development of a novel application toolkit for reconfigurable computer systems, its architecture and operation principles. The toolkit provides the translation of procedural programs in C to configuration files for field-programmable gate arrays in 6 stages. The conversion of procedural program in C to parallel program in COLAMO (Common Oriental Language for Architecture of Multi Objects) is performed using four additional programs: the “Angel ” translator and three preprocessors called the “Mermaid ”, the “Procrustes” and the “Nutcracker ”. At the first stage, the “Angel ” translates the C program into the absolutely parallel program in the COLAMO language. During the second stage, the information dependences of the initial C program are analyzed, scalar variables are split, and arrays are stretched by iterations. Then, at the third stage, the COLAMO code is converted to the parallel and pipeline form using the partition of arrays and loops into the vector and strea components. The fourth stage involves the transformation of the COLAMO program to the scalable parallel and pipeline form. The optional fifth stage, which is aimed at the reduction of the base subgraph, is executed only in the case of the lack of hardware resource for the structural implementation of the base subgraph of a problem. At the sixth stage, the COLAMO program is transformed to the unique computational structure and several cadrs designed for the architecture of the chosen reconfigurable computer system. The distinctive feature of the developed toolkit is the support of the resource-independent computing, which allows for the scaling of calculations in both cases of increase (induction) and decrease (reduction) in available hardware resources.

Compact planar reconfigurable UWB‐MIMO antenna with on‐demand worldwide interoperability for microwave access/wireless local area network rejection

In this study, a compact ultrawideband (UWB) multiple-input-multiple-output (MIMO) antenna with reconfigurable band notch characteristics is presented. The key feature of the antenna is its novel dual-band notch technique which blocks worldwide interoperability for microwave access or wireless local area network band interference. The UWB-MIMO property is achieved by two square monopoles separated by grounded multi-branch T-shaped stub. The reconfigurable dual-band notch operation is performed by PIN diodes integrated in a parasitic resonant structure in the ground plane. The antenna has a compact size of 40 × 20 mm 2 , with the operating frequency band of 3-11 GHz, where port isolation is better than 15 dB. The MIMO performance is ensured by calculating envelope correlation coefficient for the isotropic, indoor and outdoor environment.

Optical complex media as universal reconfigurable linear operators

Performing linear operations using optical devices is a crucial building block in many fields ranging from telecommunications to optical analog computation and machine learning. For many of these applications, key requirements are robustness to fabrication inaccuracies, reconfigurability, and scalability. We propose a way to perform linear operations using complex optical media such as multimode fibers or scattering media as a computational platform driven by wavefront shaping. Given a large random transmission matrix representing light propagation in such a medium, we can extract any desired smaller linear operator by finding suitable input and output projectors. We demonstrate this concept by finding input wavefronts using a spatial light modulator that cause the complex medium to act as a desired complex-valued linear operator on the optical field. We experimentally build several 16×16 operators and discuss the fundamental limits of the scalability of our approach. It offers the prospect of reconfigurable, robust, and easy-to-fabricate linear optical analog computation units.

MmWave Backhaul Testbed Configurability Using Software-Defined Networking

Future mobile data traffic predictions expect a significant increase in user data traffic, requiring new forms of mobile network infrastructures. Fifth generation (5G) communication standards propose the densification of small cell access base stations (BSs) in order to provide multigigabit and low latency connectivity. This densification requires a high capacity backhaul network. Using optical links to connect all the small cells is economically not feasible for large scale radio access networks where multiple BSs are deployed. A wireless backhaul formed by a mesh of millimeter-wave (mmWave) links is an attractive mobile backhaul solution, as flexible wireless (multihop) paths can be formed to interconnect all the access BSs. Moreover, a wireless backhaul allows the dynamic reconfiguration of the backhaul topology to match varying traffic demands or adaptively power on/off small cells for green backhaul operation. However, conducting and precisely controlling reconfiguration experiments over real mmWave multihop networks is a challenging task. In this paper, we develop a Software-Defined Networking (SDN) based approach to enable such a dynamic backhaul reconfiguration and use real-world mmWave equipment to setup a SDN-enabled mmWave testbed to conduct various reconfiguration experiments. In our approach, the SDN control plane is not only responsible for configuring the forwarding plane but also for the link configuration, antenna alignment, and adaptive mesh node power on/off operations. We implement the SDN-based reconfiguration operations in a testbed with four nodes, each equipped with multiple mmWave interfaces that can be mechanically steered to connect to different neighbors. We evaluate the impact of various reconfiguration operations on existing user traffic using a set of extensive testbed measurements. Moreover, we measure the impact of the channel assignment on existing traffic, showing that a setup with an optimal channel assignment between the mesh links can result in a 44% throughput increase, when compared to a suboptimal configuration.

A Phase-Calibration Method for Vector-Sum Phase Shifters Using a Self-Generated LUT

This paper presents a new self-calibration method for vector-sum phase shifters (PS) to compensate for process variations and achieve reconfigurable operating frequency. The calibration system generates a look-up table for the control voltages of the variable-gain amplifiers of the PS to minimize the rms phase error at a frequency of interest. The calibration system consists of a coupled-line coupler, an amplifier, a power detector (PD), an analog-to-digital converter, and a data processing unit. In this calibration method, first, the amplitudes of IQ vectors are swept and their powers are measured. Then, phase errors are calculated from these power measurements using the cosine formula. Finally, the vector pairs providing the least phase error are chosen for each desired phase shift. The practicality of the proposed system is demonstrated by realizing a self-calibrated $X$ -band 7-b PS fabricated in IHP 0.25- $\mu \text{m}$ SiGe BiCMOS technology, including the on-chip coupler, amplifier, and PD. The calibration system improves the rms phase error by at least 1°, does not degrade the rms gain error, and increases the insertion loss by 1.6 dB. The self-calibrated PS achieves a 2° rms phase error across $X$ -band frequencies. The overall chip size is 2.6 mm2. The power consumption of the PS and the overall system are 110 and 233 mW, respectively. This built-in calibration system mitigates process variation effects, and the performance of the PS can be optimized for any center frequency across $X$ -band.

Dynamic Cloud Network Control Under Reconfiguration Delay and Cost

Network virtualization and programmability allow operators to deploy a wide range of services over a common physical infrastructure and elastically allocate cloud and network resources according to changing requirements. While the elastic reconfiguration of virtual resources enables dynamically scaling capacity in order to support service demands with minimal operational cost, reconfiguration operations make resources unavailable during a given time period and may incur additional cost. In this paper, we address the dynamic cloud network control problem under non-negligible reconfiguration delay and cost. We show that while the capacity region remains unchanged regardless of the reconfiguration delay/cost values, a reconfiguration-agnostic policy may fail to guarantee throughput-optimality and minimum cost under nonzero reconfiguration delay/cost. We then present an adaptive dynamic cloud network control policy that allows network nodes to make local flow scheduling and resource allocation decisions while controlling the frequency of reconfiguration in order to support any input rate in the capacity region and achieve arbitrarily close to minimum cost for any finite reconfiguration delay/cost values.

A Multi-Clustering Approach to Scale Distributed Tenant Networks for Mobile Edge Computing

Fifth generation (5G) mobile networks will lead to a deep integration between networks and applications. Through novel paradigms like network functions virtualization and edge computing, the new classes of heterogeneous application services will be enabled to run close to the mobile end-user devices with zero-perceived latency and fully-cognitive dynamic reconfiguration capabilities. Such “vertical” applications exhibit diverse performance/scalability requirements, and will rely on highly distributed, extremely virtualized, multi-tenant, and software-defined infrastructures. In such a context, handling the required operations in a scalable and dynamic fashion will be of paramount importance. A specific aspect, addressed by software-defined networking (SDN), regards the provision of suitable communication channels, once resource allocation mechanisms have performed the most efficient deployment of virtual network function instances, and VNF chaining needs to be implemented to enable network services. In this respect, this paper introduces the multi-cluster overlay (MCO) network paradigm: a tunnel-less SDN scheme for scalable realization of virtual tenant networks across the 5G distributed infrastructure, able to support (bulk) migrations of software instances among geo-distributed computing resources in a seamless and effective fashion. The numerical simulation and experimental results show that the MCO achieves up to over one order of magnitude smaller number of forwarding rules than the other state-of-the-art SDN mechanisms, while also assuring high performance during reconfiguration operations.

The Adaptive Avionics Platform

Current avionics systems are composed of standardized components. Configuring these components requires millions of configuration parameters. The creation of configurations requires a lot of time and effort in the avionics development process. The AAP consists of standardized modules for computing and peripheral interaction that are self-configuring and fault tolerant. During an organizational phase, the actual topology is detected, the applications are distributed, and all message routes are configured. With an ACMS, the feasibility of the AAP is shown. The ACMS utilizes COTS components, POSIX-API, and Ethernet. In 2.5 min., it is able to configure itself. Moreover, it can withstand a single hardware fault in CPMs, I0Ms, and the network without extra effort. Due to the lack of a reconfigurable certifiable operating system, missing hard real-time capabilities and certifiability are the greatest drawback that will be addressed in the future. The aim is to enable self-configuring and self-fault-tolerant avionics in the safety-critical domain up to DAL A.

Reconfigurable Graphene Circular Polarization Reflectarray/Transmitarray Antenna

Abstract Reconfigurable reflectarray/transmitarray antennas have found broad applications in wireless communication due to their low cost, small size, flexible design, and superior performance. However, one common drawback of most current designs is the complex reconfiguration operation, which restricts their further applications. In this research, a new design strategy for reconfigurable reflectarray/transmitarray antennas is proposed and shown. Specifically, a circularly polarized $11 \times 11$ unit-cell graphene-based reflectarray/transmitarray antenna covering an area of $1.1 \times 1.1$ mm2 is designed, with a graphene-based frequency selective surface (FSS) as a ground. By adjusting the electric field, a dynamic change in the complex conductivity of graphene is achieved, which in turn changes the phase and the resonance point of the reflected or transmitted wave at the element. By tuning the size of the patch and changing the chemical potential of graphene, the element of the reflectarray/transmitarray operated at 1 THz can provide a dynamic phase range of more than ${360^ \circ }$. The simulation results show that the designed antenna can be dynamically reconfigured between the circularly polarized reflectarray/transmitarray antenna of the single structure, and has potential applications in emerging terahertz communication systems.

Frequency tuning varactor-loaded reconfigurable antenna for m-WiMAX and WLAN applications

A design approach for a microstrip patch antenna to achieve the reconfigurable dual-band operation with a tunable device is presented in this work. The approach uses a BB833 varactor diode in the middle of a slotted patch antenna which which is able to produce dual-band resonant frequencies. The reconfigurable antenna is designed and simulated in CST Microwave Studio® software and is later, fabricated on a FR-4 substrate with a dielectric constant, of 4.5, loss tangent, tan δ of 0.019 and thickness, h of 1.6 mm. By changing the DC voltages of the varactor diode, different capacitance values of the varactor diode are obtained which dictate the specific resonant frequencies. From the simulation results, the capacitance value of 0.5 pF with a bias voltage of 2.0 V is chosen as it produces the required dual-band resonant frequencies at 3.38 GHz and 5.37 GHz for desired applications in the m-WiMAX and WLAN bands.

Tunable terahertz amplification based on photoexcited active graphene hyperbolic metamaterials [Invited

The efficient amplification and lasing of electromagnetic radiation at terahertz (THz) frequencies is a non-trivial task achieved mainly by quantum cascade laser configurations with limited tunability and narrowband functionality. There is a strong need of compact and efficient THz electromagnetic sources with reconfigurable operation in a broad frequency range. Photoexcited graphene can act as the gain medium to produce coherent radiation at low THz frequencies but its response is very weak due to its ultrathin thickness. In this work, we demonstrate an alternative design to achieve efficient tunable and compact THz amplifiers and lasers with broadband operation based on active THz hyperbolic metamaterials (HMM) designed by multiple stacked photoexcited graphene layers separated by thin dielectric sheets. The hyperbolic THz response of the proposed ultrathin active HMM is analytically and numerically studied and characterized. When the graphene-based HMM structure is periodically patterned, a broadband slow-wave propagation regime is identified, thanks to the hyperbolic dispersion. In this scenario, reconfigurable amplification of THz waves in a broad frequency range is obtained, which can be made tunable by varying the quasi-Fermi level of graphene. We demonstrate that the THz response of the presented tunable THz amplifiers or lasers is controlled by the incident optical pumping (photodoping) and the loaded dielectric materials in the HMM waveguide array, an interesting property that can have great potential for THz amplification, emission, and sensing applications.

Self-organizing control for satellite clusters using artificial potential function in terms of relative orbital elements

Self-organizing control for satellite clusters is a challenging and promising problem which has drawn considerable attention in the recent past. The artificial potential function method has been widely used for self-organizing control due to its elegant mathematical analysis and simplicity. This paper proposes a set of self-organizing control rules for satellite clusters described by artificial potential functions, so that the reconfiguration, uniform distribution and collision avoidance operations can be achieved spontaneously. It may work regardless of the failure of satellites, attendance of new members or existence of space debris, and the corresponding communication and control system are completely distributed. Particularly, the artificial potential functions are written in terms of relative orbital elements derived from T–H equations, so that the self-organizing control can reflect relative motion dynamics, and guide the satellite along a fuel-efficient trajectory. The proposed method is especially suitable for highly distributed micro-satellite clusters and large-scale clusters to track moving targets, with few fuel cost and relatively high control accuracy, and it is applicable to clusters in either deep space or near-earth space. The stability of the control was proved by Lyapunov second method, and verified by Monte Carlo simulation. Finally, the comparison between self-organizing control and fuel-optimal control was made to demonstrate the performance properties.

Analysis of slot-based radiators using TCM and its application in MIMO antennas

In this article, with the help of the theory of characteristic modes (TCM), it is found that the introduction of circular slots in a chassis modifies the chassis modes. Based on the location of the slot, different chassis modes will be affected. For a fixed location, the slot to chassis size ratio plays an important role in its effect on the radiating bandwidth (BW). For a small size ratio, a modified chassis mode will be created without affecting the radiating BW. The current concentration across the slot depends on the shape of the slot (circular, rectangular, triangular, or square) and its location on the chassis. Moreover, the effect of multiple circular slots on the chassis modes is investigated. For slots introduced in a symmetrical fashion, that is, four elements, the modes are not affected and are similar to the original chassis ones. We also investigate the principle behind frequency reconfigurability using TCM analysis. The varactors used for frequency reconfigurability do not alter the radiating BW (Modal Significance plots) but only help in the input impedance matching at different frequency bands of the same mode. If a mode is excited purely using a proper feeding arrangement, the same frequency reconfigurable antenna will behave as a wide band one. Based on the detailed analysis presented in this work, a compact multiple-input-multiple-output annular slot frequency reconfigurable antenna operating between 1.8 and 2.45 GHz is presented. Frequency tuning is achieved using varactor diodes.

Exploring a SOT-MRAM Based In-Memory Computing for Data Processing

In this paper, we propose a Spin-Orbit Torque Magnetic Random-Access Memory (SOT-MRAM) array design that can simultaneously work as non-volatile memory and implement a reconfigurable in-memory logic operation without add-on logic circuits. The computed output can be simply read out like a typical MRAM bit-cell through the modified peripheral circuit. Such intrinsic in-memory computation can be used to process data locally and transfer the “cooked” data to the primary processing unit (i.e., CPU or GPU) for complex computations with high precision requirement. It greatly reduces the power-hungry and long-distance data communication, and further leads to extreme parallel computation within memory. In this work, we further propose an in-memory edge extraction algorithm as a case study to demonstrate the efficiency of the in-memory pre-processing methodology. The simulation results show that our edge extraction method reduces data communication as much as 8x for grayscale image, thus greatly reducing system energy consumption. Meanwhile, the F-measure result shows only <inline-formula><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula> 10 percent degradation compared to conventional edge detection operator, such as Prewitt, Sobel, and Roberts. Moreover, the edges extracted from the memory show comparable good quality with Canny edges in the context of edge-based motion detection and cross-modality object recognition.

Design and Fabrication of a Frequency and Polarization Reconfigurable Microwave Antenna on a Printed Partially Magnetized Ferrite Substrate

Design of a polarization reconfigurable and frequency-tunable patch antenna operating in the partially magnetized state of a ferrite substrate is presented in this communication. A low-cost additive manufacturing process based on a custom iron-oxide magnetic ink (to realize the magnetic substrate) and a silver-organo-complex metallic ink (to realize the antenna) has been used to demonstrate a novel fully printed magnetically controlled antenna. The magnetic substrate is characterized for its magnetostatic and microwave properties. The ink shows a saturation magnetic flux density of 156 mT with a squareness of 0.26. A prototype patch antenna at 6 GHz is implemented on the magnetic substrate using inkjet printing. When excited by an external magnetic field, the antenna shows frequency splitting and polarization reconfigurability. The measured results agree well with the simulation model of the antenna in the partially magnetized state. A maximum tuning range of 16.7% and 5% for the two splitted frequency points is obtained with circular polarizations of the opposite sense. The results show the viability of reconfigurable and tunable radio frequency components on partially magnetized substrates through low-cost additive manufacturing techniques.

Performance of a Multifunctional Robot for Natural Orifice Transluminal Endoscopic Surgery.

Natural orifice transluminal endoscopic surgery (NOTES) has gained attention as a revolutionary technique with its potential advantages in eliminating skin incisions, shortening recovery time, and decreasing postoperative complications; however, its practical application is still constrained by the complexity of navigation through the surgical field and paucity of available instruments. Current progress on NOTES focuses on designing flexible articulated robots or fully inserted bimanual robots to address the limitations. However, the lack of multitasking tools, trade-offs between size and power, and lack of sufficient surgical force are too often neglected. The authors designed a bimanual robot with a multifunctional manipulator, which can realize on-site instrument-change according to surgeon needs. An articulated drive mechanism with 2 independent curvature sections was designed to deliver the robot to the surgical site. A corresponding reconfiguration operation sequence was formulated to ease insertion and thereby decrease the design trade-off between size and power. This article presents 3 benchtop and animal tests to evaluate the robotic surgery approach and demonstrate the effectiveness of the robot.

Wideband bandpass‐to‐all‐stop reconfigurable filtering power divider with bandwidth control and all‐passband isolation

A novel wideband bandpass-to-all-stop reconfigurable filtering power divider is proposed in this study, which allows for four-order bandpass-to-all-stop reconfigurable operating function and equal power division. Its circuit configuration includes the cascaded coupled-line sections with tight coupling to extend the impedance transforming. Furthermore, with the introduction of the half-wavelength open-circuit stubs, which controls the bandwidth, extra transmission poles located at the cut-off frequency are generated, thus resulting in high frequency selectivity. Moreover, by using a single resistor between input coupled-lines, the high all-passband isolation can be achieved. The grounding are then loaded to the output coupled-lines to enable bandpass-to-all-stop operating functionality. For demonstration, a prototype operating at 2 GHz is designed, simulated, and measured with a 15 dB bandwidth of 51%, 19 dB stopband rejection up to 5 GHz, and 14.5 dB all-passband isolation, which shows a good agreement between the simulated and measured results.

A 130 nm 165 nJ/frame Compressed-Domain Smashed-Filter-Based Mixed-Signal Classifier for “In-Sensor” Analytics in Smart Cameras

To avoid data deluge at the back end, it is imperative that advanced sensor nodes perform “in-sensor” processing to extract relevant features from data. We propose a compressed-domain smashed-filter-based object recognition system and measurements from a 130 nm mixed-signal test chip to demonstrate reconfigurable and ultra-low power operation. We measure greater than 90% accuracy in object localization with 165 nJ energy per frame on image data sets.

A Wideband Frequency Tunable FSS for Electromagnetic Shielding Applications

A reconfigurable frequency-selective surface (RFSS) for electromagnetic shielding applications is presented in this letter. The unit cell of the proposed RFSS contains a pair of shorted square loops separated by a uniform distance. Wideband RFSS with the frequency tuning ratio of 1:2.34 achieved by varying the horizontal spacing is proposed. The RFSS covers the frequencies 3.5, 5, and 5.8 GHz shielding the WiMAX, WLAN, and ISM/WiMAX bands, respectively. The prototype of the proposed RFSS is fabricated and loaded on to the mechanical tuning setup. The tuning setup has a box frame with rotating shafts attached to the bevel gears to control the horizontal spacing. The use of collapsible linkage mechanism ensures uniform spacing during reconfigurable operation. The simulated results are validated with measurements. The proposed FSS offers wideband frequency tuning for electromagnetic shielding applications.

An approach for managing the dynamic reconfiguration of software architectures

Currently, most software systems have a dynamic nature and need to evolve at runtime. The dynamic reconfiguration of software systems is a mechanism that must be dealt with to enable the creation and destruction of component instances and their links. To reconfigure a software system, it must be stopped, patched and restarted; this causes unavailability periods which are always a problem for highly available systems. In order to address these problems, this paper presents an approach called software architecture reconfiguration approach (SAREA). We define for this approach a set of intelligent agents, each of them has a precise role in the functioning and the control of software. Our approach implements a restoring mechanism of software architecture to a fully functional state after the failure of one or more reconfiguration operations; it also proposes a reconfiguration mechanism which describes the execution process of reconfigurations.