Recent Research Projects



  • Current Projects

    1. Energy Efficient Schemes for Supporting Flexible Cache Consistency in Mobile Ad Hoc Networks (Project No. 7002494, CityU SRG)
      2. With the proliferation of portable computing devices, peer to peer mobile computing is rapidly entering the mainstream of computing and new applications based on wireless ad hoc networks are beginning to emerge. Such applications are however still hampered by energy constraints, and caching is often used to improve performance, reduce power consumption as well as alleviate the effect of disconnection. Cache consistency strategies must however be devised, otherwise users might access stale data. Much of the existing research in cache consistency in mobile systems is devoted to infrastructure based mobile networks and cannot be applied directly to mobile ad hoc networks. Our aim in this project is to develop a cache consistency strategy for mobile clients in a mobile ad hoc network that can exploit the
    2. Energy-efficient Network-Aware Caching Strategies for Streaming Multimedia in Wireless Networks (Project No.7001778 , CityU SRG)
      Many of the emerging mobile applications will require streaming video to mobile handheld devices such as a cell phone or PDA. An important in the design of such appplications is how to conserve power, as many portable devices have a short battery life. Another issue is the nature of the wireless link, which is error-prone and susceptible to disconnection. The aim of this project is to take advantage of the rapid drop in memory prices and use caching and pre-fetching techniques to reduce the overall energy consumption of streaming video to mobile clients without compromising user perceived quality.
    3. Energy-constrained peer to peer video streaming for mobile devices (Project No.: 7001601, CityU SRG)
      Among the many emerging mobile applications, some of the more exciting ones will require streaming video to mobile hand held devices such as a cell phone or PDA. While multimedia streaming has been extensively studied and implemented in wired networks, there are many additional challenges in a mobile network environment, particularly in a peer to peer environment. A major issue is how to conserve power, since many portable devices have short battery life. The aim of this project is to design and implement a real-time streaming protocol that will conserve energy, and also to build a peer to peer video delivery system that will not only transmit a given video stream within a prescribed energy budget but also to provide the best possible user perceived quality by adapting to changing network conditions.
  • Lists of Recent Research Projects (Principal Investigator)

    1. Location Management Schemes for Supporting Location Dependent Continuous Queries in Cellular Networks (Project No.: 7001544, CityU SRG)
      Advances in wireless network technology has led to the development of many new mobile applications that needs to track moving objects e.g. an ambulance driver might want to know the number and up-to-date location of other ambulances in the vicinity that can support its mission. To satisfy this types of query, which is known as a Location Dependent Continuous Query (LDCQ), the location of such objects need to be updated periodically; which takes up significant amount of valuable bandwidth. Most existing research on location management are devoted to voice-centric traffic and assumes the users/objects being tracked are independent. Since the objects involved in a LDCQ may be located in different cells with different network loading, it is possible that their tracking error might be different, which can affect the overall accuracy of the LDCQ. The objective of this research is to devise an adaptive location management strategy can ensure acceptable accuracy for multiple LDCQs in a cellular network environment even when the allocation of bandwidth in each cell is uneven.
    2. Real-time Information Dissemination in Mobile Environments (Project No.: 9040431, CERG)
      Many new applications based on real time data distribution over mobile network are beginning to appear in technologically advanced countries. An example of these applications is the real time distribution of financial information such as stock prices to large number of end users via mobile phones. This trend has special significance for Hong Kong, which depends on superior information technology to support its role as an international financial center. However, two properties of mobile networks pose special problems: the capacity of the down-link is typically much larger than that of the up-link, and the quality of service is much poorer than conventional fixed-line networks. In this research, we will formulate broadcast strategies that will ensure data can be broadcast to users reliably within the specified deadline. We will study the use of caching to improve overall performance, and we will look at realistic scenarios where there are multiple data requests in a single query.
    3. Cache Maintenance Strategies for Mobile Web-based Systems (Project No. 7001117, CityU SRG)
      Explosive growth in mobile network technology and Web-based applications has led to many new applications. Examples include real-time retrieval of financial information such as stock prices as well as electronic shopping, all executed using a mobile phone or a mobile computing device. This trend has special significance for Hong Kong, which depends on superior information technology to support its role as an international financial center. However, a challenging problem is that the transmission capacity of the mobile link is typically much smaller than that of a conventional network, and the mobile link is also prone to disconnection. Caching, or storing frequently used data, at the user's device is an effective solution to these problems. A major challenge, however, is to ensure the data at the user cache and at the data source are consistent. Moreover, since the user cache is usually small, a suitable replacement strategy must be derived when the cache is full. The objective of this research is to formulate a cache maintenance strategy which will improve the response time of mobile applications, included Web-based applications, and at the same time reduce the likelihood of user unknowingly accessing stale or inconsistent data.
    4. Neural Network Based Integrated Traffic Management for ATM Networks (Project No.: 7000795, CityU SRG)
      ATM is a critical technology in constructing the infrastructure of future high speed networks. A key challenge is to derive techniques to management the available bandwidth so that traffic with diverse service requirements can be met efficiently. While much work has been done based on known assumptions of traffic sources, neural network based approaches which adapt and have learning ability are seen to be more realistic in the emerging multimedia world. Past research has established the applicability of neural network approach. This project will develop a neural network based traffic management model for ATM networks. The effectiveness of various techniques and comparison with conventional methods will be evaluated. The aim is to arrive at an integrated system to provide for overall traffic management of heterogeneous traffic sources. Extensive simulation using realistic traffic scenarios will be used to verify the model.
  • Other Projects (as Co-Investigator)

    1. Adaptive Strategies for Processing of Continuous Queries on Real-time Data in Mobile Computing Systems (Project No. 9040697, CERG)
      In this research project, we will study the issues important for efficient processing of continuous queries, which are generated from mobile clients and require access to the real-time data items maintained by the system. Associated with a continuous query is its begin time and end time. During the begin time and end time, the query will be evaluated continuously to monitor its interested data items. In particular, we are interested in using Push and Pull for processing of the continuous queries. These two techniques have been shown to be efficient for management and dissemination of real-time data items in distributed and mobile environment. In Push, once a continuous query has been generated by a mobile client, it will be sent to the database server through a mobile network. The query will stay at the database server and be processed there continuously until its end time. Any query result will be pushed to the initiating client once it is generated. In Pull, the continuous query will generate requests from its initiating client periodically to the database server (pulling). After the database server has served a request and has transmitted the query result to the initiating client, the request will be destroyed. When it receives the next request from the continuous query, it will process the request as a new request.
    2. Monitoring of Real-time Data of Moving Objects in Mobile Computing Systems (Project No. 7001259, CityU SRG)
      One of the important mobile computing applications is to monitor real-time information of moving objects for mobile clients. Once it satisfies the conditions of any queries of the mobile clients, the mobile clients will be informed immediately. Some typical applications are fleet management systems and mobile phone location management systems. Two important design issues in providing timely real-time information of moving objects to mobile clients are update processing and data monitoring. In this research work, we will first design efficient update methods for reporting the real-time status of moving objects to a database system. Different data monitoring schemes will then be explored to work with the update method to evaluate the queries from mobile clients. In the design of the update generation and monitoring schemes, we need to consider the unique characteristics of the underlying mobile network, i.e., low bandwidth and frequent disconnection, and the real-time properties of moving objects, i.e. high rate of changes.
    3. Efficient Concurrency Control Protocols for Transactions in Mobile Real-time Database Systems (Project No. 9040512, CERG)
      Recent advances in mobile communication technology have made mobile information services a reality. Various novel mobile computing systems, such as tele-medicine systems, real-time traffic information and navigation systems, and mobile Internet stock trading systems, are emerging as mobile users require instant access to information using their palmtops, personal digital assistant (PDA) and notebook computers, no matter where they are. An important characteristic of the new mobile computing applications is that they have to handle transactions in a real-time manner and the data values of the databases are highly dynamic. Meeting the timing requirements is vital to the usefulness of the systems. For example, in a stock trading system, a late response of a stock analysis transaction may result in a loss of a good trading opportunity. The consequence of missing a transaction deadline in a tele-medicine system for ambulance services may even result in the loss of a human life. In this research work, we will design new concurrency control protocols based on our previous research in real-time database systems to meet the real-time requirements of the mobile applications. An important consideration in the design of the protocols is that the unique characteristics of underlying mobile networks and the applications characteristics have to be considered so that the overheads for detecting and resolving data conflicts can be minimized.

Publications

Graduate Students

  • Current

  • Alumni

    1. Dick, Hung Hon Tak(2004)
      Thesis title: RETINA: A Real-time Navigation System
    2. Ng Siu Wah (2002)
      Thesis title: TCP-Friendly Streaming Protocols in Mobile Computing Environment
    3. Hunter Leung Hei Wing (2002)
      Thesis title: Protocols for Consistent Data Broadcast and Cache Management in Mobile Computing Systems
    4. Au Mei Wei (2001)
      Thesis title: An Efficient Protocol for Broadcasting Consistent Data to Read-Only Transactions from Mobile Clients
    5. Joe Yuen Chun Hung (2000)
      Thesis title: Data Dissemination Strategies in Mobile Computing Environment
    6. Peter Tsang Hin Ho (1998)
      Thesis title: Performance Evaluation of the FDDI Medium Access Protocol for Real-time Traffic

BSCS Final Year Projects

Potential BSCS Final Year Projects (2008-2009)


  1. Landmark based navigation system

    The aim of this project is to provide an image / landmark based navigation system to users. Most vehicular navigation system only provides maps to assist the user. Unfortunately in cities like Hong Kong where the GPS system does not work very well, some additional aids such as images and more importantly, easily identified landmarks can be very helpful to the driver who is lost. The system will also provide route planning with embedded landmarks based on the user's preferences.  
  2. Web Archival System

    Currently it is not easy to trace the history of certain Web sites. For instance, a user might want to track the personnel changes in the Computer Science Department at City University of Hong Kong based on its Web site. However there is no convenient tool to do that. The objective of this project is design a Web archival system that will poll selected Web sites periodically, determine whether there has been any change, retrieve the modified version of the Web site and archive it, and also provide a user-friendly interface for searching and browsing the archived information. Some of the challenges include change detection mechanism and determination of Web retrieval update interval.

    Required skill: Web based application programming.