Qos modeling for performance evaluation over evolved 3g networks

The end-to-end Quality of Service (QoS) must be ensured along the whole network in order to achieve the desired service quality for the end user. In hybrid wired-wireless networks, the wireless subsystem is usually the bottleneck of the whole network. The aim of our work is to obtain a QoS model to evaluate the performance of data services over evolved 3G radio links. This paper focuses on the protocols and mechanisms at the radio interface, which is a variable-rate multiuser and multichannel subsystem. Proposed QoS models for such scenario include selective retransmissions, adaptive modulation and coding, as well as a cross-layer mechanism that allows the link layer to adapt itself to a dynamically changing channel state. The proposed model is based on a bottom-up approach, which considers the cumulative performance degradation along protocol layers and predicts the performance of different services in specific environments. Numerical parameters at the physical layer resemble those proposed for 3GPP Long Term Evolution (LTE). By means of both analytical (wherever possible) and semi-analytical methods, streaming service quality indicators have been evaluated at different radio layers.