Jonathan C. Li

Multi Impairment Monitoring for Optical Networks

As optical networks become more complex, the need for in-line monitoring of more than just channel wavelength, power and OSNR becomes compelling. In this paper we describe an asynchronous delay tap sampling technique coupled with statistical machine learning that enables a single monitor to measure multiple simultaneous impairments on multiple formats. We demonstrate the technique for simultaneous measures of CD and 1st order PMD on a 40 Gbit/s NRZ-DPSK signal.

On TCP performance enhancing proxies in a wireless environment

TCP performance enhancement in wireless access networks is an important ongoing area of research. It is known that the hostile nature of the wireless channel and the mobile nature of wireless users interact adversely with standard TCP congestion control mechanisms [1], causing a drastic reduction in throughput. This article surveys a selection of different approaches to managing TCP performance over wireless links, and presents the results of simulation and field trial results of a novel TCP performance enhancing proxy over diverse cellular radio access technologies based on the GSM, cdma2000, and UMTS standards. The proposed TRL TCP performance enhancing proxy has the advantages of being completely transparent to both TCP endpoints and tunable to different access technologies, and frequently achieves the maximum throughput available from any of the studied radio access technologies.

Telehealth to improve asthma control in pregnancy: A randomized controlled trial

Poorly controlled asthma during pregnancy is hazardous for both mother and foetus. Better asthma control may be achieved if patients are involved in regular self‐monitoring of symptoms and self‐management according to a written asthma action plan. Telehealth applications to optimize asthma management and outcomes in pregnant women have not yet been evaluated. This study evaluated the efficacy of a telehealth programme supported by a handheld respiratory device in improving asthma control during pregnancy.

Consumer radar: Technology and limitations

Recent advances in micro-electronics have created the possibility of building very low cost, very small, high performance single chip Radar systems. Concurrent with this technological advance, a diverse range of new applications for such radar systems is emerging. The coming consumer radar revolution is on the verge of entering the market place in areas including automotive radar, bicycle radar, micro-UAV radar, and many other applications. This short paper briefly describes the current state of the technology covering RF, signal processing and antenna systems. We also introduce recent work on performance limitations of such systems including radar information theory and its connections with quantum mechanics.

Transponder Dependence Issues in Asynchronous Delay-Tap Monitoring

Asynchronous delay-tap sampling is an effective method enabling monitoring of multiple optical impairments on live traffic. This letter addresses impairment measurement issues arising from transponder manufacturing variations and presents methods to mitigate this.

Simultaneous and Independent OSNR and Chromatic Dispersion Monitoring Using Empirical Moments of Asynchronously Sampled Signal Amplitudes

We analytically investigate and derive equations for the empirical moments of asynchronously sampled signal amplitudes as functions of signal power, noise power, and accumulated chromatic dispersion (CD) of a transmission link. The solutions of these equations enable low-cost, simultaneous and independent monitoring of in-band optical signal-to-noise ratio (OSNR) and CD of the fiber link for various modulation formats and data rates. Numerical simulations are performed to validate the proposed technique and the results demonstrate independent OSNR and CD monitoring with good accuracy and large monitoring ranges. The influence of first-order polarization-mode dispersion (PMD) on the accuracy of the proposed monitoring technique is also investigated.

Intelligent Automated Diagnosis of Client Device Bottlenecks in Private Clouds

We present an automated solution for rapid diagnosis of client device problems in private cloud environments: the Intelligent Automated Client Diagnostic (IACD) system. Clients are diagnosed with the aid of Transmission Control Protocol (TCP) packet traces, by (i) observation of anomalous artifacts occurring as a result of each fault and (ii) subsequent use of the inference capabilities of soft-margin Support Vector Machine (SVM) classifiers. The IACD system features a modular design and is extendible to new faults, with detection capability unaffected by the TCP variant used at the client. Experimental evaluation of the IACD system in a controlled environment demonstrated an overall diagnostic accuracy of 98%.

Enabling ASON Routing via Novel Signal Quality Metrics

We propose a new algorithm for path selection in automatically switched optical networks (ASONs), based on eye closure penalty, Q-factor and a modified OSPF protocol. We demonstrate the technique for a nine node network.

Adapting a Low-Cost Selective Compliant Articulated Robotic Arm for Spillage Avoidance

Flexible automation systems provide the needed adaptability to serve shorter-term projects and specialty applications in biochemical analysis. A low-cost selective compliant articulated robotic arm designed for liquid spillage avoidance is developed here. In the vertical-plane robotic arm movement test, the signals from an inertial measurement unit (IMU) and accelerometer were able to sense collisions. In the horizontal movement test, however, only the signals from the IMU enabled collision to be detected. Using a calculation method developed, it was possible to chart the regions where the obstacle was likely to be located when a collision occurred. The low cost of the IMU and its easy incorporation into the robotic arm offer the potential to meet the pressures of lowering operating costs, apply laboratory automation in resource-limited venues, and obviate human intervention in response to sudden disease outbreaks.

AUTOMATED INFERENCE SYSTEM FOR END -TO - END DIAGNOSIS OF NETWORK PERFORMANCE ISSUES IN CLIENT -TERMINAL DEVICES

Traditional network diagnosis methods of Client-Terminal Device (CTD) problems tend to be laborintensive, time consuming, and contribute to increased customer dissatisfaction. In this paper, we propose an automated solution for rapidly diagnose the root causes of network performance issues in CTD. Based on a new intelligent inference technique, we create the Intelligent Automated Client Diagnostic (IACD) system, which only relies on collection of Transmission Control Protocol (TCP) packet traces. Using soft-margin Support Vector Machine (SVM) classifiers, the system (i) distinguishes link problems from client problems and (ii) identifies characteristics unique to the specific fault to report the root cause. The modular design of the system enables support for new access link and fault types. Experimental evaluation demonstrated the capability of the IACD system to distinguish between faulty and healthy links and to diagnose the client faults with 98% accuracy. The system can perform fault diagnosis independent of the user’s specific TCP implementation, enabling diagnosis of diverse range of client devices.