Polychronis Koutsakis

Telemedicine traffic transmission has gained in importance during the past few years. Due to the fact that it carries critical information regarding the patients’ condition, the expedited and errorless transmission of multimedia telemedicine traffic is of fundamental importance. The prioritized or guaranteed transmission of telemedicine traffic, however, can lead to the violation of the Quality of Service (QoS) requirements of regular traffic users and to the loss of guaranteed bandwidth in cases when it is left unused, due to the infrequent nature of telemedicine traffic. To resolve these problems, we propose a Multiple Access Control (MAC) protocol, for the integrated transmission of regular and telemedicine traffic transmission over next generation cellular networks and an adaptive bandwidth reservation scheme based on road map information and on user mobility and a fair scheduling scheme for telemedicine traffic transmission over cellular networks. The combination of the two schemes achieves high channel bandwidth utilization while offering full priority to telemedicine traffic over regular traffic. Three scheduling algorithms are evaluated, quantitatively and qualitatively, in terms of the QoS and the fairness they offer to different types of traffic.

Due to the burstiness of video traffic, video modeling is very important in order to evaluate the performance of future wired and wireless networks. In this paper, we investigate the possibility of modeling this type of traffic with well-known distributions. Our results regarding the behavior of single videoconference traces provide significant insight and help to build a Discrete Autoregressive (DAR(1)) model to capture the behavior of multiplexed MPEG-4 videoconference movies from VBR coders.

The provision of acceptable Quality-of-Service (QoS) for integrated multimedia traffic over a geosynchronous earth orbit (GEO) satellite network demands the existence of a well-designed Medium Access Control (MAC) protocol. This paper proposes a new dynamic satellite bandwidth allocation technique which is based on accurate videoconference traffic prediction. Our work is combined with another work on data traffic modeling and prediction and is shown to provide very good throughput and delay results.

In this work we propose and evaluate mechanisms for the multiplexing and the integrated delivery of Video and Data Traffic over a Wireless Cellular High Speed Packet Switched Network. We envision a system where the Mobile Terminals are considered to be high performance devices with extended storage capabilities which can act like cache memories streaming multimedia material. We focus on the uplink channel and we thoroughly investigate the system’s performance under a variety of possible loads which consist of actual MPEG-4 streams and Data Traffic.

A new medium access control (MAC) protocol for mobile wireless communications is presented and investigated. We explore, via an extensive simulation study, the performance of the protocol when integrating voice and data traffic over a wireless channel of medium capacity (referring mostly to outdoor microcellular environments). Data message arrivals are assumed to occur according to a Poisson process and to vary in length according to a geometric distribution. We evaluate the voice packet dropping probability and access delay, as well as the data packet access and data message transmission delays for various voice and data load conditions. By combining two novel ideas of ours with a useful idea which has been proposed in other MAC schemes, we obtain very good voice sources multiplexing results along with most satisfactory voice and data performance and quality of service (QoS) requirements servicing. This is demonstrated by the nature of our results, as well as by the comparison of both the concepts and the results of our scheme to those of MAC schemes which were recently introduced in the literature.