The third generation UMTS(Universal Mobile Telecommunication Systems) networks has opened up doors to many applications such as real time video calling, video mail, video on demand, interactive video services, etc. and has unfolded new horizons in the prov
Audiovisual Quality Assessment for 3G Networks in Support of E-Healthcare Services
Asiya Khan, Zhuoqun Li, Lingfen Sun, Emmanuel Ifeachor
Centre for Signal Processing and Multimedia Communication School of Computing, Communications and Electronics
University of Plymouth Plymouth PL4 8AA, UK.
Email: ; ; ;
Keywords: Quality of Service, 3G, Audio Quality, Video Quality, Asterisk®, E-healthcare
The third generation UMTS(Universal Mobile Telecommunication Systems) networks has opened up doors to many applications such as real time video calling, video mail, video on demand, interactive video services, etc. and has unfolded new horizons in the provision of e-healthcare because of increased bandwidth. With 3G wireless networks it is possible for healthcare professionals wherever they are to monitor patients anywhere and anytime thus improving the quality of their lives. The purpose of this paper is to present a critical review of the existing literature on audiovisual quality over 3G mobile networks and hence provide an understanding of the key factors that affect audiovisual quality of service and further discuss the existing quality assessment methods for voice and video. We then present results of our preliminary investigation to assess the quality of a video call over live 3G network subjectively. Finally, we discuss the QoS implications in the application of 3G networks in e-healthcare. 1 Introduction
Quality of Service(QoS) as defined by ITU-T is “the collective effect of service performance which determines the degree of satisfaction of a user of that service.” Therefore, successful large-scale deployment of 3G networks and wide applications depend on how good the quality of voice and video is and whether they can meet the end user or a customers’ satisfaction. For both commercial, domestic and time critical healthcare applications it is crucial for equipment providers, network operators and service providers to be able to assess, predict and possibly control the end to end perceptual voice and video quality for 3G wireless networks.
QoS in 3G wireless networks is based on a service classification of four classes: conversational, streaming,
interactive and background – each class corresponding to
different application requirements. For example, the conversational class has the highest QoS requirements, while the background class has the lowest and can be seen as best-effort traffic class. In the interactive class the bandwidth and delay requirements are lower, but the reliability of the transfer must be high. Streaming class applications include video and audio streaming. The class has high bandwidth requirements
but tolerates longer transfer delays. QoS of e-healthcare services as dictated by the medical professional and the patients(end users) will fit in all of the above four traffic classes depending on the required service. For example the
QoS requirement for videoconferencing would be both in the interactive and streaming classes. For voice and video communications 3G works on a 64 kb/s circuit switched connection: QoS comes at a cost of bandwidth. This means that a limited amount of data can be sent, making audio and video quality a real challenge.
The current trends in the development of wireless internet applications (IEEE 802.11) and mobile systems indicate that the future internet architecture will need to support various applications with different QoS requirements. More recently the term QoE(Quality of Experience) has been used and defined as the users perceived QoS. It has been proposed in [2,3,4] that a better QoE can be achieved when the QoS is considered both in the network and application layers as a whole. In the application layer QoS is driven by factors such as resolution, frame rate, colour, video codec type, audio codec type, layering strategy, sampling rate, number of channels, etc. The network layer introduces impairment
parameters such as jitter, delay, burstiness, latency, packet loss, etc. The paper is structured as follows. Section 2 summarizes the
QoS assessment methods for voice and video outlining subjective and objectives measurements and their tools. In section 3 we give an overview of the audiovisual quality assessment highlighting the factors that affect voice and video QoS. In section 4 we assess the audio/video quality of a video call subjectively and present preliminary test results from our experiment. Section 5 discusses the e-healthcare applications supported by 3G networks and their QoS requirements. Finally, section 6 concludes the paper and highlights areas of further work. 2 QOS Assessment Methods for Voice and Video QoS for voice and video can be measured both subjectively and objectively. Subjective quality is the users’ perception of service quality(ITU-T P.800) and is measured through subjective quality assessment. The performance of the system under test is rated directly (Absolute Category Rating, ACR) or relative to the subjective quality of a reference