Project Supervisor: Prof. David Siew

2. An Early Video Slice Discard Scheme for VBR Service
The Variable Bit Rate (VBR) service class defined by the ATM Forum is proposed to support continuous transmission of bursty traffics, such as compressed audio and video streams. Unfortunately, the characteristics of these traffics are difficult, if not impossible, to define. Consequently, excess resource, in terms of its peak cell rate and maximum burst size, must be reserved to accommodate the fluctuation in transmission rates in order that the Quality of Service (QoS) requirements can be adequately guaranteed. However, it is well known that temporal media of video and audio are high tolerable to short-term distortions (or breaks). Hence, it should be possible to maximise the number of network connections by selective discarding the least important sequence of the data streams. Since most of the video streams are MPEG compressed, they follow a strict hierarchical structure, which can be exploited in the selective discards. This hierarchical structure comprises of the smallest encoding unit, Block, Macroblock, Slice, Frame, Group of Pictures, and Sequence.

By discarding many smallest data units (video slice) instead of one entire MPEG frame, freed resources can be used to accommodate additional connections without introducing significant distortion in the reconstructed sequence. By considering also the different important of different coded frames: I, P, or B the impact of the distortion due to selective discards can further be reduces. Unlike the selective cell discarding mechanism based on the Cell Loss Priority (CLP), early slice discard remaining cells belonging to a packet where one or more cells have already been lost. This prevents the forwarding of cells belonging to corrupt video slice through the ATM network, thereby conserving bandwidth.

In this project, the student is expected to propose and evaluate an approach to delimit and tag such independent video slice at the AAL for early discard. The student shall also study and propose a mechanism for message passing using the CLP and PTI bits in the cell header to facilitate the selective discarding of affected cells within each video slice as opposed to dropping of cells at random from multiple video frames. OPNET will be used in the project to evaluate and analyse the mechansim proposed.

Project Supervisor: Prof. Ang Yew Hock

3. Performance Evaluation of TCP/IP traffic over ABR Service
Available Bit Rate (ABR) service has been defined to support data transfer over ATM network. In this project, the student is required to investigate how the widely used transport protocol, TCP, performs when it is used on top of the ABR service. The investigation will be concentrated on various factors, such as TCP's congestion mechanism, window size, ABR parameters and switch buffering, that may affect the throughput of TCP traffic. The stdent is require to use OPNET to model various TCP congestion control techniques and analysis the network performance.

Project Supervisor: Prof. Jim M Ng

4. Study on the performance of leaky bucket policing for heterogeneous traffic
The behavior of the traffic sources representing the applications which make use of ATM technology in the future are not yet well understood and characterized. Given the trend in multimedia applications, it can be assumed that traffic appearing at the input to a switched connection (and hence at the input to the leaky bucket) is likely to be of heterogeneous nature. This project explores how the throughput and QoS will be affected under such heterogeneous traffic patterns. OPNET simulation tool will be used in this project.

Project Supervisor: Prof. Quah Tong Seng

5. Using case-based reasoning tool to perform traffic shaping for ATM network
Traffic management for asynchronous transmission is important to ensure that bandwidth is efficiently utilized. Many researchers have tried to enhance traffic management using Artificial Intelligence. Out of these attempts, traffic shaping using case-based reasoning tool is a possibility.

One possible way to maximize the usage or the throughput of a multimedia ATM network is via traffic shaping. By means of traffic shaping, the amount of traffic injected into a network may be kept within the maximum usable capacity of the network. This project requires using case-based reasoning tool to manage the arriving traffic and prioritize their injection into the network, and OPNET will be used to simulate the network performance.

Project Supervisor: Prof. Quah Tong Seng

6. Courses Using OPNET
E6135 - Simulation and Network Design is a MSc course instructed by Asst Prof. Jim Ng. The course covers queuing analysis as well as simulation techniques for the performance analysis and design of computer networks. OPNET is one of the network simulation tools that the students will learn in class for network performance analysis.