Specification, mapping and control for QoS adaptation

Cristian Koliver, Klara Nahrstedt, Jean Marie Farines, Joni Da Silva Fraga, Sandra Aparecida Sandri

Research output: Contribution to journalArticlepeer-review


In this paper we describe a fuzzy-control approach for quality of service (QoS) adaptation, needed in distributed multimedia applications. QoS adaptation is necessary (a) due to sudden variations in network resource availability, especially in the case of Internet, and (b) due to multiple applications requiring shared resource such as bandwidth. To solve the problem of QoS adaptation, several sub-problems need to be considered: (1) mapping of user perception and different combinations of applications QoS values onto a uniform quality metric, (2) estimation, control and adjustment of application QoS parameters in case of network and other resource congestion, and (3) enforcement algorithm which reacts according to adapted QoS parameters. Our approach is to solve the QoS adaptation using the integration of (a) quality degree function, which maps the application QoS parameters into a metric, called quality degree, (b) fuzzy controller, which controls, estimates and adjusts the application QoS parameters according to resource availability, and (c) filter algorithms, which are the services to enforce the adapted QoS parameters. The quality degree function associates quality degree as the quality measure with different combinations of application QoS values. This function is influenced by the user's perception of quality. The fuzzy control takes the results of the quality degree function, estimates the new quality degree and its corresponding quality level, predicts the new application QoS parameters, and adjusts them. The results of the adapted QoS parameters are then used by the filter algorithms to enforce the changes, proposed by the fuzzy controller, by allocating bandwidth to the application according to its QoS parameter values. We have implemented and applied the quality degree function, the fuzzy controller, and the filter algorithms to the video distribution system (VDS). The results of VDS over the local area network show that (1) the target system improves user perceived QoS at the receivers, and (2) the bandwidth utilization increases significantly when using our fuzzy-control approach for QoS adaptation.

Original languageEnglish (US)
Pages (from-to)143-174
Number of pages32
JournalReal-Time Systems
Issue number1-2
StatePublished - 2002


  • Adaptation
  • Fuzzy controller
  • Multimedia
  • Quality degree
  • Quality of service

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Modeling and Simulation
  • Computer Science Applications
  • Computer Networks and Communications
  • Control and Optimization
  • Electrical and Electronic Engineering


Dive into the research topics of 'Specification, mapping and control for QoS adaptation'. Together they form a unique fingerprint.

Cite this