• Supporting Remote Sensing and Control over IP Networks

    This is the subject matter of my Ph.D. dissertation. We aim to solve the communication problems associated with remotely controlling robotic sensors and collecting the feedback such as video, audio etc. I designed an overlay network based framework to improve the QoS for real-time teleoperated robotic tasks through the Internet. A similar mechanism is also developed for wireless (MANET) environments.

  • Improve QoS of Teleoperation Systems over Overlay Networks

    For Internet based real-time teleoperation systems, random time delay can cause instability in the closed loop control system and hence hinder task accomplishment. Event based control systems have been proposed to overcome the instability caused by the random time delay. High latency at the transport layer can still impede effective and reliable execution of tasks with high dexterity requirements. Network QoS based dynamic resource allocation has been proposed to increase the efficiency and reliability of task execution. However, these approaches only try to mitigate or overcome the effects of random time delay and do not address the cause of latency issues in the communication channel.

    This research addresses the efficiency and reliability requirements for supermedia enhanced teleoperated systems by reducing the end-to-end transmission latency through the use of overlay networks. The proposed system (Supermedia TRansport over Overlay Networks, STRON) reduces the transmission latency by using multiple, disjoint paths in overlay networks. The proposed system facilitates reliable and efficient task completion for tasks with high dexterity requirements.

    Simulation of the system under NS2 shows the system works better than traditional approaches.

    NS2 plugins of the supermedia application. Features include: (1) the OPSM module of STRON; (2) a modified TFRC agent that supports payloads; (3) a modified link module that can change the link capacity according to traces, etc.

    Experimental validation of the proposed teleoperated system using the PlanetLab (the overlay relay agent) Network is provided for the task of teleoperating a mobile manipulator system.

    This is a joint work with RA Lab under the direction of Dr. Mutka and Dr. Xi.

    Publications: Networking 2005 (poster, and a longer technical report version Technical Report MSU-CSE-05-01), ICRA 2005 (slides), and IROS 2005 (slides).

    A poster presented to the CSE department. Another poster presented to the CSE department, which was awarded the best posters prize.

  • Improved Transport Service for Remote Sensing and Control over Wireless Networks

    In remote sensing and control applications, such as bilateral teleoperated systems, the signal transmissions between an operator and the slave manipulators have different QoS requirements in comparison to traditional network traffic. The challenge for supporting teleoperated systems over wireless networks is more difficult in comparison to wired networks. The media streams involved in teleoperated systems differentiate themselves from other media types in that they require both reliable and smooth delivery. Reliable delivery requires that the transport service have TCP style semantics. By being smooth, the transport service should be able to deliver the control and sensing data with both the average latency and the standard deviation of the latency bounded and reduced. We conducted numerous teleoperated experiments using our system. Our teleoperation experiments and simulations show that traditional transport services have great difficulty meeting the latency requirements of delivering sensing and control data over wireless networks. This research project proposes an improved Transport service for Remote Sensing and Control (TRSC) . The service reduces the end-to-end latency and the standard deviation of the latency (jitter) for real-time reliable media in mobile ad hoc networks by using forward error correction encoding and multiple network paths.

    Part of the research is published in MASS 2005 (slides).

  • Modeling and Design of Mobile Surveillance Networks

    Networked surveillance systems provide an extended perception and distributed reasoning capability in monitored environments through the use of multiple networked sensors. The challenge for such large scale networked systems is to design an efficient modeling and analysis tool and devise stable control algorithms for accomplishing the surveillance task. Current feature (point) based visual servo and tracking techniques generally employed do not provide an optimal solution for the surveillance task. This research project presents a mutational analysis approach for shapes, and shape based control to model and design mechanisms for such active surveillance systems. The techniques of image based Hausdorff tracking and cooperative Hausdorff tracking are studied. Our experimental results demonstrate the efficacy of the proposed approach for tracking targets over a large area.

    This is collaborated with Amit Goradia and Dr. Ning Xi, et al.

    Part of the research is published in IROS 2005 (slides), AIM 2005 and FLAIRS 2006.

  • Available Bandwidth Measurement through One Way Delay Trend Detection

    Available bandwidth (AB) defined as a minimum spare capacity of links constituting a network path is an important QoS characteristic of the path. We propose to improve a whole range of AB measurement tools that send sequences of measurement packets (called trains) across the network path. If transmission times of packets in the train, called One Way Delays (OWD), show an increasing trend as packet sequence number in the train increases, then AB is believed to be lower than the rate at which the train was sent. In contrast, an absence of a trend indicates that AB is higher than the rate of the train. We propose an algorithm for efficient OWD trend detection and compare it to widely used OWD trend detection tests.

    Collaborated with Alexander L Chobanyan under the direction of Dr. Mutka.

    Part of the research is published in GLOBECOM 2005.

    cpuload: a tool to push the CPU load to a certain extent to facilitate the measurement test. A wrapper to run pathload on PlanetLab nodes. tgen: a UDP traffic generator that generates traffic between two end hosts according to a given rate.

  • A Topology-Aware Routing Protocol for Hierarchical Wireless Sensor Networks

    We proposed a Topology-Aware (TPAW) routing protocol for hierarchical wireless sensor networks (WSNs), where each cluster head is capable of determining its nearest base station (BS) and reporting timely to this very BS. A dynamic route recovery method is proposed in the protocol to handle route failures. The recovery is on demand as the AODV protocol does. However, in order to save routing overheads, the TPAW takes advantage of the topology information obtained from a probing procedure to "direct" the recovery, where the probing is periodically initiated by the BS's to refresh the topology information. In contrast to the DSDV protocol where each node broadcasts into the network for route updating, the updating in TPAW is centralized by the few number of BS's. As a result, the TPAW protocol is a hybrid of a centralized DSDV and AODV protocol. As an effort to alleviate the frequency of probing and hence reduce the network traffic, a robust majority vote method is proposed in TPAW protocol to locally update the topology.

    On going research collaborated with Huahui Wang and Dr. Tongtong Li. The work is published in EIT 2006.

  • QoS Aware Wireless Bandwidth Aggregation for 3G Cellular Communications

    Some mobile devices are beginning to support both cellular and IEEE 802.11 based network interfaces. Although rates are increasing, current cellular networks provide relatively low bandwidth that do not meet the QoS requirements of many high-demanding multimedia applications. In this research, we propose an integrated network architecture that utilizes both wireless interfaces to provide better QoS support by QoS Aware Wireless Bandwidth Aggregation (QAWBA). Via QAWBA, mobile nodes form a mobile ad hoc network (MANET) using their IEEE 802.11 interfaces to share their cellular link capacity. Some mobile nodes act as proxies to contribute their idle cellular links to support a QoS request that may exceed the available bandwidth of any individual mobile node. A K-path proxy discovery algorithm is proposed for fast and efficient proxy discovery. Simulation results show that QAWBA can significantly improve network utilization and the admission rate of QoS requests.

    This is a joint research with Danyu Zhu under the direction of Dr. Mutka. The work is published in Qshine 2004 and GLOBECOM 2005.

    We also designed a MAC layer retransmission rate based mechanism to determine the optimal number of peers in a bandwidth sharing system. The work is published in MASS 2006.

  • Solving Minimal Dominating Set Problem

    CSE830 (Design and Theory of Algorithms) term project. Minimal dominating set is one of the major NP-Complete problems. I developed a brute force algorithm with a lot of heuristic optimizations. Here is the C Code.

  • Security of Windows LM Authentication

    CSE891 (Selected Topics on Computer Security) term project. I discussed security issues related with the Windows authentication protocols. Here are the Slides.

  • Motion Prediction in Mobile Communication Systems from a Historical and Geographical Perspective

    CSE812 (Advanced Operating Systems) term project, collaborated with Hong Chen and Xiaomei Liu. We proposed an algorithm to predict the motion of mobile communication hosts based on neural network algorithms. Here are the report and slides.

  • Exploring Dynamic Branch Prediction Methods

    This is the term project of CSE820 (Computer Architecture), working together with Ming Wu and Junwei Zhou. It is a literature survey of current (when I was taking the class) technologies of predicting branches in modern processors. The report is here.

  • Network Measurement and Analysis Platform

    This is my major master degree work under the direction of Prof. Chuanshan Gao in the Computer Science and Engineering Department of Fudan University. My colleagues were Suo Cong, Gansha Wu, Liangxiu Han, Chunbo Chu, Yan Liu, Feng Rao, Jun Yang, Zhige Wang, etc.

    The Internet has historically been insufficiently measured compared with its fast development. With the rapid, tremendous, and ceaseless growth of the network, this issue is becoming even worse. The global infrastructure of the Internet makes it a very complex and gigantic system to analyze diagnostically.

    However, the insights into the network performance are very critical to the operation, maintenance, design and research of the network. It is well known now that the systemic measurements of elaborate defined performance metrics would facilitate network operations and engineering. Each measurement effort provides a new window on the infrastructure for network operation, design and research. But without well-considered, strategically deployed, and collaboratively maintained measurement tools/infrastructure, these windows cannot offer any useful insight.

    The FUNAP (Fudan University Network Analysis Platform) project focuses mainly on researching the methodologies applied in measuring the network performance, analyzing and simulating the behavior of the network. The results from FUNAP can be used not only in network operation and problem diagnosis but also in researching the evolution of next generation network. I worked in this group from Sept. 1999 to Jun. 2002.

    Here are some related projects of our peers:

    The Internet Performance Measurement and Analysis Project,;

    Towards a systemic understanding of the Internet organism: a framework for the creation of a network analysis Infrastructure, 1998,;

    An Infrastructure for Internet Performance Measurements, June 1999,

    Bell Labs Internet Traffic Research:

    CAIDA, a famous project on Traffic Engineering:,

    In Chaos, Solitons and Fractals. In Small and Micro Computer System, Chinese. In PDCS 2001. In the Third International Asia-Pacific Web Conference (the Presentation).

    My master thesis (in Chinese) in Fudan University. Proposal of this paper (MS PowerPoint)

  • Web-Based Document Management System

    A joint project of GE China Lighting Technical Center and Fudan University.

    Published in Computer Applications and Software, Chinese.

  • Others

    Co-translated "Understanding Data Communications & Networks, Second Edition", Shay, W. A., Machine Industry Publishing House. Mar., 2000

    Co-translated "Distributed System Design", Jie Wu, Machine Industry Publishing House. Feb., 2001.

    Second Prize in the 5th English Lecture Contest of Fudan University Graduate School, May, 2000. You can find the lecture script and the slides. I used to be the Board Master of the Foreign Language Board of Fudan BBS, here are introduction to the board and the slides.

    An introduction to Tool Command Language(MS PowerPoint) and TCP/IP(MS PowerPoint) presented in Kingnet Security, Inc. where I worked for a part time position in Shanghai.