Fiber Bus Research Articles

Research on prediction weighted interpolated polling dynamic bandwidth allocation for optical fiber bus based on gigabit passive optical network

Optical fiber bus technology is an important research direction in communication systems of electronic devices in special vehicle platforms. According to the requirements for communication quality between devices in special vehicle platforms, an optical fiber bus based on gigabit passive optical network topology is proposed. A data cache-based predictive weighted interpolated polling dynamic bandwidth allocation method is presented and investigated for the optical fiber bus’s upstream bandwidth allocation. The network controller establishes a weighted buffer area for the communication requirements in the polling period according to the type and data volume of the network terminal (NT) data stream and dynamically allocates the bandwidth of each optical NT to better meet the communication requirements for different data within the special device platform. Verification is done by means of OPNET software simulation and the establishment of a NT simulation test system in the laboratory. This proves that the proposed dynamic bandwidth allocation algorithm can reduce the end-to-end delay of RS422 port data by more than 50% and meet the Ethernet and controller area network port data delay requirements.

Survivable Deployments of Optical Sensor Networks against Multiple Failures and Disasters: A Survey.

Optical sensing that integrates communication and sensing functions is playing a more and more important role in both military and civil applications. Incorporating optical sensing and optical communication, optical sensor networks (OSNs) that undertake the task of high-speed and large-capacity applications and sensing data transmissions have become an important communication infrastructure. However, multiple failures and disasters in OSNs can cause serious sensing provisioning problems. To ensure uninterrupted sensing data transmission, survivability has always been an important research emphasis. This paper focuses on the survivable deployment of OSNs against multiple failures and disasters. We first review and evaluate the existing survivability technologies developed for or applied to OSNs, such as fiber bus protection, self-healing architecture, and 1 + 1 protection. We then elaborate on the disaster-resilient survivability requirement of OSNs. Moreover, we propose a new k-node (edge) sensing connectivity concept, which ensures the connectivity between sensing data and users. Based on k-node (edge) sensing connectivity, the disaster-resilient survivability technologies are developed. The key technologies necessary to implement k-node (edge) sensing connectivity are also elaborated. Recently, artificial intelligence (AI) has developed rapidly. It can be used to improve the survivability of OSNs. This paper details potential development directions of survivability technologies of optical sensing in OSNs employing AI.

Design of Switching System Based on FC-AE-1553 Bus

As 1553B bus system is also widely used in modern avionics system, so in the new bus system development, not only the quality improvement on the performance is needed, but also should be required to be compatible with the original avionics equipment complying with 1553Bbus protocol , maximum reducing avionics system upgrade difficulty. Based on this consideration, the American National Standards Committee has developed the upper mapping of FC protocol—FC-AE-1553 agreement. FC-AE-155 agreement takes full advantages of the fibre channel and also gives full consideration to the requirement of being compatible with the original 1553B equipment, so the system upgrade can be easily realized. Conduct the fibre bus study based on FC-AE-1553, raise the hardware and software design methods and complete the control system demonstration verification based on fibre-optic bus. At the same time, conduct the bridging technology of FC-AE-1553 and MIL-STD-1553B, construct two types of demonstration verification system for bus bridging, breaking the hardware and software technology of FC-AE-1553 and MIL-STD-1553B bridging and establish the hybrid structure of the high and low speed bus, to meet the needs of the actual model, which plays a very important significance for the further development of China's aerospace business.

原发性小肠肿瘤的诊断与治疗(附40例报告)

目的：探讨原发性小肠肿瘤的临床特点、误诊原因及诊断方法。方法：回顾性分析了40例原发性小肠肿瘤的临床资料。结果：术前只确诊13例，其余均误诊，误诊率达67.5%。本组均手术治疗，良性肿瘤均行肿瘤及局部肠管切除，共10例，恶性肿瘤行根治性切除24例，姑息性切除3例，捷径手术3例，术后近期死亡1例，余均出院。结论：本病少见，容易误诊，要引起足够的重视。上消化道内镜检查，X线钡餐检查，BUS及CT检查是诊断本病的主要方法。 Objective: To explore the clinical characteristics, cause of misdiagnosis and diagnosis methods of primary small intestinal tumor. Methods: Retrospective analyses of the clinical data were made on 40 cases of primary small bowel tumors. Results: Before operation, 13 cases were given confirmed diagnosis of small intestinal tumor. The rate of misdiagnosis is 67.5%. Partial excisions were administered in 10 cases with benign small intestinal tumor. Radical excisions were performed in 24 cases with malignant tumors. Palliative excision in 3 cases and shortcut operation in 3 cases. A patient died after operation and other 39 were discharged from hospital. Conclusions: This disease is rare and easy to misdiagnose, and we need to take it seriously. Fiber endoscopy, X-ray, barium meal, BUS and CT were the main methods of diagnosis.

Optical Fiber Bus Protection Network to Multiplex Sensors: Experimental Validation of Self-Diagnosis

The experimental demonstration of a resilient wavelength division multiplexed fiber bus network to interconnect sensors is reported. The network recovers operation after failures and it performs “self-diagnosis,” the identification of the failed constituent(s) from the patterns of surviving end-to-end connections at its operating wavelengths. We provide clear evidence for the channel arrivals predicted by theory. In doing so, we explore the potential for spurious signals caused by reflections from broken fiber ends. Appropriate precautionary measures, especially the imposition of electronic thresholds at the receivers, can greatly reduce the scope for false diagnoses. Software to predict the failure site within the network from the arriving channels at the receivers is also reported. We describe how to coordinate self-diagnosis with protection switching so as to reduce the momentary service interruption.

Optical Fiber Bus Protection Network to Multiplex Sensors: Dedicated Line and Dedicated Path Operation

This paper reports the simulation of a self-healing fiber bus network for the wavelength multiplexing of sensors. The network can recover service after one or more failures by “dedicated line” or “dedicated path” protection. We derive an easily implemented analytical method to determine the surviving channels after multiple failures and use it to explore the consequences of all double failures throughout the network. Dedicated line protection is a versatile option to provide full service recovery after many failure pairs. However, when it can be afforded, dedicated path protection offers even better performance and we list the failure pairs for which this is so. We also study the survival of telemetry signaling after double failures and show that the large majority of instances do not prevent its functioning. The network is, therefore, very resilient.

Optical Fiber Bus Protection Network to Multiplex Sensors: Self-Diagnostic Operation

We present a mathematical model for a wavelength- division multiplexed self-healing optical fiber bus network to interconnect an array of sensors. The network uses protection switching to reestablish service after the failure of one or more of its constituent elements. Our model is a matrix-vector formalism that divides the network into blocks. It predicts which wavelengths arrive at the receiver node when damage has occurred in one or more places. We study single and multiple failures within one block, categorizing and tabulating all combinations of surviving wavelengths. In this way, we correlate the received wavelengths with the failure location(s). The network thus provides “self-diagnosis,” which we define to be the determination of its own sites of failure from network management information, without requiring external resources.

Optical Fiber Bus Protection Network to Multiplex Sensors: Amplification by Remotely Pumped EDFAs

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We report a physical-layer study of an optical fiber network for the multiplexing of sensors that can regain service after damage to its fibers. It is a symmetrical dual-fiber bus that uses “dedicated-line” or “dedicated-path” protection switching in response to a failure. Amplification is normally needed when serving more than <formula formulatype="inline"><tex Notation="TeX">$\sim$</tex></formula>10 sensors, even when the network's directional couplers are optimized, and we simulate the use of remotely pumped spans of erbium-doped fiber to eliminate all electrical power feeds outside the end nodes. Our description of the network's management and signaling and its actions in response to a failure emphasizes the amplifier pump control. We model a network with dedicated-line protection to serve 40 sensors, showing that good channel power equalization and signal-to-noise ratios are possible by carefully optimizing the erbium-doped fiber lengths and including gain-equalizing filters. </para>

Double Raman Amplified Bus Networks for Wavelength-Division Multiplexing of Fiber-Optic Sensors

In this paper, three different double Raman fiber bus networks are compared and demonstrated experimentally for the first time as a means of gathering information from wavelength-division-multiplexed optical sensors: the double-bus scheme, the improved double-bus configuration, and the hybrid topology. We report how these structures reduce the received amplified-spontaneous-scattering noise generated. This low-noise configuration yields signal-to-noise ratios over 43 dB and increases the number of sensors that could be multiplexed in a single structure. Furthermore, the last one enables the reutilization of the gratings' wavelengths

Pickup suppression in sagnac-based fiber-optic acoustic sensor array

Large-scale acoustic fiber sensor arrays consisting of hundreds of hydrophones distributed along kilometers-long fiber buses are required for applications such as undersea oil exploration. Sagnac-based sensor arrays (SSAs) exhibit attractive performance; however, the acoustic wave incident on the buses generates a pickup signal that can swamp the signals from the hydrophones. A simple technique for reducing this unwanted pickup is proposed, modeled, and demonstrated by periodically inserting deaf hydrophones in the buses instead of hydrophones so the pickup signal is measured at different locations along the buses. The first method directly subtracts the deaf hydrophone signal from the signal seen by the adjacent hydrophone (true signal and pickup) to recover the true hydrophone signal. This method is limited to small signal amplitudes by the nonlinearity of the Sagnac interferometer. The second method corrects the nonlinearity before pickup subtraction and allows in principle a full suppression of the pickup. When applied to an experimental two-rung SSA, this technique produced a -18.6-dB pickup suppression for pickup amplitudes as large as 0.44 rad and signal amplitudes of up to 0.44 rad and -15 dB for a signal as large as 0.88 rad. These values are limited by the accuracy of the 8-bit data acquisition and/or electronic noise. With a low-noise 12-bit data acquisition, the pickup suppression for small signal amplitudes is predicted to be -35 dB. This paper makes headway toward practical SSAs.

Optical arithmetic unit using bit-WDM

A novel arithmetic unit is proposed consisting of a pipelined optical ripple carry adder that adds two words with bits multiplexed by different wavelengths on a single fiber. The addition result is returned to a fiber bus in the same format as the incoming words. The corresponding operand bit pairs are split off the fiber using wavelength division demultiplexers. Full adders compute the sum for each bit pair and the carry from the next lower significant bit pair. The full adder uses couplers and NOT, NOR and novel XOR logic gates constructed using semiconductor optical amplifiers for gain and wavelength shifting.

Single and double distributed optical amplifier fiber bus networks with wavelength-division multiplexing for photonic sensors

Two different optical fiber bus networks are compared and demonstrated experimentally as means of gathering information from four wavelength-division-multiplexed photonic sensors. Both topologies include distributed amplification, which allows one to overcome the limitation in the maximum number of sensors that can be multiplexed in a single structure. Results obtained with a dual-bus topology are compared with those achieved with a single-bus network.

Design of an opto-electronic VLSI/parallel fibre bus

We present a design for an opto-electronic bus system based on commercial parallel fibre ribbon transmission systems and opto-electronic VLSI smart pixel arrays. We describe the design of the individual components, their integration, the performance limits and potential applications.

Folded fibre bus interconnects with distributed amplification

An optical fibre network for application as an interconnect within major nodes is investigated theoretically. The network is configured as a folded bus in which the spine consists of erbium doped fibre to overcome the power division at the couplers. It is argued that high received powers with a narrow dynamic range can be obtained simultaneously with bit rates in the order of 10 Gbit/s and bit error rates of 10 −12 or less.

Single and double distributed optical amplifier fiber bus networks with wavelength division multiplexing for photonic sensors

This paper presents numerical simulations of single and dual fiber bus networks with distributed amplification, which are used for the wavelength division multiplexing of photonic sensors. The model upon which the simulations are based has been compared to a previously published experimental result and good agreement has been obtained. A novel technique for allocating the signal wavelength to the sensor position in order to equalize the received signal power is also discussed.

Optimization of large-scale fiber sensor arrays incorporating multiple optical amplifiers. I. Signal-to-noise ratio

We report on optimizing the signal-to-noise ratio (SNR) of large-scale fiber sensor arrays employing erbium-doped fiber amplifier (EDFA) telemetry with respect to the number of sensors per rung, the number of amplifiers per array, and the coupling ratio between the fiber buses and the rungs. Broad optimum regions are found, providing design flexibility to minimize pump power requirements. Simulations predict that 300 sensors can be multiplexed on a fiber pair while maintaining a high sensitivity (1 /spl mu/rad//spl radic/(Hz)) for all sensors with a moderate input pump power (<1 W).

Optimization of large-scale fiber sensor arrays incorporating multiple optical amplifiers. Part II: pump power

For part I see, ibid., p. 218, 1998. We discuss how to minimize the pump power required for large-scale fiber sensor arrays employing erbium-doped fiber amplifier (EDFA) telemetry with respect to the number of amplifiers per bus, number of sensors per rung, and the gain per amplifier. For a large array, the pump power requirement is dominated by passive component losses along the array. We investigate several methods, including alternative array topologies, to reduce the power requirement while minimizing the impact on the signal-to-noise ratio (SNR). We define an optimum topology which requires less than 1 W of 1480 nm pump power per bus to support 200 high sensitivity (1 /spl mu/rad//spl radic/(Hz)) sensors on a pair of fiber buses, a power requirement that is reasonable and attainable with available laser diodes.

High speed TDMA folded fibre bus LAN: design method

A simple model of an optical fibre based folded bus network for application as a time division multiplexed interconnect for computer work stations is presented. The model predicts the best positioning of discrete amplifiers to achieve the power budget requirements, as well as the optimum coupling ratios for the couplers on the bus.

Optical Amplified Recirculating Delay Lines Transient Response Effect on Hybrid Fiber Buses

This paper presents novel theoretical and experimental results of the temporal response of optical amplified recirculating delay lines. These optical amplified recirculating delay lines have been used for equalizing sensor signals from hybrid fiber buses. To assure nondistortion of telecommunication data in these fiber buses, optical equalizer high transient times must be avoided. The time analysis carried out in this work allows the development of equalizer design rules to overcome the transient time limitations and fulfil the steady-state equalizing scheme.

An efficient wavelength reusing/migrating/sharing protocol for dual bus lightwave networks

High-speed lightwave networks employing linear fiber bus topology have become attractive with the emergency of erbium-doped optical amplifiers. Moreover, the huge network capacity in a dual bus lightwave network is obtained by several parallely transmitting channels (wavelengths) on each bus. By applying the wavelength reusing concept, nonoverlapping traffic in the network can be serviced simultaneously to achieve high network throughput. It is also possible that a new incoming request is blocked even the bandwidth between the source and the destination is available. Nevertheless, this request may be accommodated by migrating some existing connections. Due to the number of wavelengths is limited, some requests may further share the same wavelength to improve the network throughput. In this paper, an efficient distributed wavelength reusing/migrating/sharing protocol (WRMSP) for the dual bus lightwave networks (DBLN) is proposed. This protocol consists of three efficient schemes for carrying out the wavelength reusing, migration and sharing, respectively. Simulation results show that for a limited number of wavelengths and tunable receivers, the proposed protocol substantially improve the network throughput and access delay under general traffic demands.