Previous Research

Multimedia Multi-peer Communications

With emerging distributed multimedia group applications a lack of support for end-to-end group communication was observed. This included the management of multiple communications entities (peers) at an end-to-end level that require different topologies such as multicast (1:n) and N-plex (n:m) for their communication. Integrated communication support has to be provided for discrete as well as continuous media taking into account effective QoS support for heterogeneous communication peers. As part of this research two end-to-end communication services were developed. They are distinguished by the communication topology they provide; the M-Connection Service provides controlled and arbitrated multicast communication whereas N2N Connection Service offers controlled and arbitrated N-plex communication. The services are provided by a modular and configurable transport system architecture where end-to-end functions and mechanisms are separated according to problem spheres. The problem of heterogeneous receivers was addressed by using QoS filters (capable of adapting resource requirements of a data stream by changing its structure), which are placed at strategic points of the dissemination tree between the sender and the receivers.

Publications:

A. Mauthe: End-to-End Support for Multimedia Multipeer Communications, Ph.D. Thesis, Computing Department, Lancaster University, Bailrigg, Lancaster, LA1 4YR, U.K., 1998

A. Mauthe, N. Yeadon, D. Hutchison, F. Garcia: QoS Filtering and Resource Reservation in an Internet Environment, in Multimedia Tools and Applications Journal, Kluwer Academic Publishers, Vol. 13, No. 3, 2001

A. Mauthe, L. Mathy, D. Hutchison: Communication Services for Multimedia Systems, in High-Performance Networks for Multimedia Applications, edited by A. Danthine, O. Spaniol, W. Effelsberg, D. Ferrari, Kluwer Academic Publishers, Netherlands, 1999

Projects:

GCommS:  (Group Communication Support for Distributed Multimedia Systems). The project was an EPSRC funded activity within the Distributed Multimedia Group of the Computing Department at Lancaster University established in 1994. The GCommS project was concerned with end-to-end communications support for multiparty multimedia applications. It addressed the problem of group communication at the transport layer and above at a so called distributed multimedia application platform.
 

Quality of Service (QoS) Support for Multimedia Tasks

Multimedia processes (especially interactive and continuous media tasks) require special support from the underlying infrastructure (i.e. operating system and communication system). Apart from processing requirements they also have timing requirements that have to be met in order to consider the processing of a task successful. These requirements can be expressed in processing/transmission time, deadline, jitter and period in the case of periodic tasks. A number of scheduling schemes have been devised; most of them are based on the Earliest Deadline First or Rate Monotonic scheme. In the context of the operating system the original work has concentrated on a meta-scheduler for priority driven scheduling schemes. This was later expanded to consider scheduling and admission testing for jitter constraint periodic threads.

Publications:

A. Mauthe, G. Coulson: Scheduling and Admission Testing for Jitter Constrained Periodic Threads, in Multimedia Systems Journal, Vol. 5, No. 5, 1997

A. Mauthe, W. Schulz, R. Steinmetz: Inside the Heidelberg Multimedia Operating System Support: Real-Time Processing of Continuous Media in OS/2, Technical Report 43.9214, IBM Technical Report, October 1992

Projects:

Associated with SUMO: the project was interested in both communications and processing support for distributed real-time/ multimedia applications in end systems. The approach was based on thread-to-thread real-time support according to user supplied quality of service (QoS) parameters. Such support, depending on the level of QoS commitment required, can require dedicated, per-connection, resource allocation in the CPU scheduler, virtual memory system and communication system.

HeiTS (Heidelberg Transport System: the HeiTS project at the IBM’s European Networking Center in Heidelberg was concerned with the development of a new generation end-to-end communication system. It aimed at a heterogeneous environment comprising several computers with different operating systems and a variety of underlying networks incorporating end-system and gateway communication functions.