Dual Ring Topology Research Articles

Wideband-tunable microwave photonic filter using dissipative self-interference microring resonators

We propose and demonstrate a widely tunable microwave photonic filter with controlled frequency agility, bandwidth reconfigurability and flexible switching functions. It is based on the self-interference microring aided by an asymmetric Mach–Zehnder interferometer, breaking the fundamental microring footprint limit and achieving a doubled free spectral range (123.2 GHz) with a strong out-of-band rejection. Simulation results show that a bandpass microwave photonic filter can be tuned across a 60 GHz frequency range with a varied 3-dB bandwidth from 2.13 GHz to 40.7 GHz in a cascaded dual-ring topology. Its RF out-of-band rejection ratio is improved by more than 60 dB in the high frequency region due to a perfect residual phase cancellation. A dual-band notch microwave photonic filter with an extinction ratio of about 50 dB and a frequency tunable range of about 27.7 GHz is also demonstrated, showing its broadly applicability. Our method highlights its suitability to improve chip-scale wideband and high-performance RF receiver systems.

Tetraphenylethene-based macrocycles with dual-ring topology: synthesis, structures, and applications

This review focuses on the eight-shaped double ring structure of tetraphenylethylene, summarizes the research progress of structures, ionic molecular structures and metal molecular structures, and looks forward to its future development direction.

A 27–44 GHz CMOS Dual-Ring Subharmonic Up-Conversion Mixer With Linearization Technique

A 27–44 GHz subharmonic up-conversion mixer using 65 nm CMOS technology is presented. For subharmonic scheme and wide RF/IF bandwidth, a dual-ring topology is developed in this mixer design. To increase the linearity and conversion gain (CG) without adding additional local oscillator (LO) power, a LO boosting linearization technique is adopted. The subharmonic up-conversion mixer achieves a measured CG of −12 dB ± 1.5 dB from a wide RF frequency of 27 to 44 GHz. The 3-dB IF bandwidth is from dc to 10 GHz. After adopting the linearization technique, the output 1-dB compression point (OP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1 dB</sub> ) of the subharmonic up-conversion mixer can be improved from −12 to −9 dBm at 38 GHz with zero addition dc consumption.

Compact dual‐mode dual‐band bandpass filter with inside–outside–reversed dual‐ring topology

A compact dual-mode dual-band bandpass filter is proposed based on the inside–outside–reversed dual-ring topology. Different from the traditional design, the total size of the filter is limited by the second passband with shorter wavelength at higher frequency, instead of the first passband with longer wavelength at lower frequency. By loading four square patches in the inner ring, the degenerate modes of the inner ring move down and form the first passband, whereas the second passband is constructed by the outer ring. By utilising the coplanar-waveguide feeding at ground plane, a prototype of the dual-band filter with two operating frequencies at 0.92 and 1.47 GHz is designed and verified experimentally.

Construction and experimental verification of a novel flexible thermal control system configuration for the autonomous on-orbit services of space missions

This paper proposed a novel flexible thermal control system (F-TCS) configuration for realizing thermal management for spacecrafts autonomous on-orbit service (A-OOS) demands. With a dual-ring topology which composes of a heat collecting bus, a heat dissipating bus, connection brunches and inter-platform service interfaces, the F-TCS may realize not only self-reconfiguration operations but also providing heat dissipation resources for other spacecrafts or cabins. The F-TCS hydraulic and thermal dynamics were modeled, a verification testbed was also established to validate the F-TCS thermal control performance. Focused on investigating the self-reconfiguration and thermal control cooperative operations, several typical A-OOS cases were imposed on the F-TCS, numerical simulations and experimental validations were respectively implemented. Both results demonstrated that the meticulously designed F-TCS is capable of offering self-topological reconfiguration with fast time response and robust temperature control performances, high systemic heat transfer efficiency is also recommended from the point of view of energy saving. The F-TCS is suggested as a promising solution for A-OOS owing to its higher reliability and promising autonomous maintenance potential which is suitable for future spacecrafts thermal management requirements.

Fault-Tolerant Algorithms for Connectivity Restoration in Wireless Sensor Networks.

As wireless sensor network (WSN) is often deployed in a hostile environment, nodes in the networks are prone to large-scale failures, resulting in the network not working normally. In this case, an effective restoration scheme is needed to restore the faulty network timely. Most of existing restoration schemes consider more about the number of deployed nodes or fault tolerance alone, but fail to take into account the fact that network coverage and topology quality are also important to a network. To address this issue, we present two algorithms named Full 2-Connectivity Restoration Algorithm (F2CRA) and Partial 3-Connectivity Restoration Algorithm (P3CRA), which restore a faulty WSN in different aspects. F2CRA constructs the fan-shaped topology structure to reduce the number of deployed nodes, while P3CRA constructs the dual-ring topology structure to improve the fault tolerance of the network. F2CRA is suitable when the restoration cost is given the priority, and P3CRA is suitable when the network quality is considered first. Compared with other algorithms, these two algorithms ensure that the network has stronger fault-tolerant function, larger coverage area and better balanced load after the restoration.

A complete real-time Ethernet solution for numerical control systems

This paper proposes a complete real-time Ethernet (RTE) solution including master and slave controllers for numerical control (NC) systems. To meet the development tendency of NC systems moving toward multi-axis coordination, high speed and high precision, one type of RTE architecture is built up with a dual ring topology. The function blocks of master/slave nodes are designed to realize the real-time communication capabilities using embedded CPU and field programmable gate array (FPGA) technologies. To reduce the minimum achievable cycle time, a cut-through transmission mechanism is employed to decrease the process latency at slave nodes, and the synchronization frame is optimized to shorten the frame duration. In order to synchronize the nodes of RTE-based NC systems accurately, a time synchronization strategy is scheduled and a proportion-integration (PI)-based phase-locked loop (PLL) is designed to keep the master clock and the slave clocks in step stably. The theoretical analysis and experimental results show that the proposed RTE solution can achieve good real-time performance with low process latency and high time-synchronization accuracy, which satisfies the real-time communication requirements of RTE-based NC systems in an economical way.

ATM switch with dual transceiver ring architecture

Different techniques exist for an asynchronous transfer mode (ATM) switch design. An ideal ATM switch has high throughput, low loss and low delay. A technique for designing an ATM switch is the use of a shared medium. In this technique a bus or ring may be used as the shared medium. A new switch that uses a dual ring as a shared medium is introduced. The dual ring topology has been proposed for local area networks and has higher throughput than a conventional ring. A throughput higher than 96%, delay less than 35 /spl mu/s and low loss are the results obtained from the performance analysis of this new switch.

Reliability analysis of distributed computing systems in ring networks

Distributed Computing System (DCS) has become very popular for its high fault-tolerance, potential for parallel processing, and better reliability performance. One of the important issues in the design of the DCS is the reliability performance. Distributed Program Reliability (DPR) has to be addressed to obtain this reliability measure. An efficient network topology is quite important for the distributed computing system. For example, the ring network has been widely used in current distributed system design. In this paper, we focus on DCS with ring topologies. We propose polynomial-time algorithms to analyze the DPR of the dual ring topology and show that solving the DPR problem on a ring of trees topology is NP-hard.

Design of a self-routing frequency division multiple access (SR-FDMA) network using an optical ring filter with or without gain as a router

Self-routing frequency division multiple access (SR-FDMA) network with ASK coherent detection and dual ring topology is proposed. The router, which employs the optical ring filter, is used as a means for selecting the desired channel carrier and at the same time as a bypass of the other channel carriers. The channel capacity and the carrier-to-noise ratio are investigated with the consideration of cross talk and power budget penalty. We find that there exists an optimum coupling coefficient of the transceiver coupler and a trade-off in selecting channel number and data rate. The results show that the router with gain can suppress the cross talk, compensate the power budget penalty, and largely increase the channel number. Therefore, with this router, a self-routing, high-density FDMA network is feasible.

Transputer-based fault-tolerant and fail-safe node for dual ring distributed railway signalling systems

Railway signalling systems are based on fault-tolerant and fail-safe techniques to provide high reliability and safety. Transputers offer multiple communication links and provide a high degree of parallelism and are being used in safety-critical and fault-tolerant applications. We propose a fault-tolerant and fail-safe node using transputers for a local area network with dual ring topology to be used in distributed railway signalling systems. The proposed scheme uses a new technique of leadership based on rotation amongst the transputers of the node. Aspects of safe shutdown, recovery, reconfiguration and clock synchronization of the fault-tolerant and fail-safe node are addressed. Formal specifications of the fail-safe node and the simulation of the proposed technique are also given.

Destination stripping dual ring: a new protocol for MANs

Abstract A new MAC protocol for ring-topology Metropolitan Area Networks (MANs) is defined. Starting from an analysis of ring-topology networks and of current MANs, guidelines for the definition of high performance MAC protocols are derived. The DSDR (Destination Stripping Dual Ring) protocol is defined applying these guidelines. Its key characteristics are the dual-ring topology and the destination stripping capability which, together with multiple tokens, slotted operation and other details, give DSDR very high performance, mainly in terms of total throughput, guaranteed throughput per station and maximum access delay. The protocol parameters can be tailored for different compromises between guaranteed throughput for delay-sensitive applications and total throughput. On each of the two rings, guaranteed throughput, with bounded access delay, can be close to twice the medium capacity under worst case hypotheses, while total throughput, under realistic hypotheses, can be close to four times the medium capacity. The maximum interval between accesses by the same station can be as low as N/2 slot times, with N stations on the network. Multicast can be supported with the same simplicity and the same cost as in other LANs and MANs.