On Revealing the ARQ Mechanism of MSTV

Ensuring a high customer satisfaction by monitoring Quality of Experience (QoE) aspects has become common practice for service providers. Such monitoring solutions, together with underlying QoE models, are mostly limited to measures captured in the core or access network and may thus neglect the QoE impact of recovery mechanisms deployed at client-side, e.g., FEC or ARQ. This limitation makes QoE models prone to mispredict QoE and consequently may lead the operators to misleading interpretations of customer experience. In this paper, we empirically study the behavior of the Microsoft TV Set-top Box (STB) with respect to the deployed ARQ recovery mechanism. As the ARQ implementation details of the STB are proprietary, we implement and simulate three ARQ algorithms of different complexities and evaluate their performance by comparing with corresponding empirical measurements. This comparison reveals insights into the ARQ scheme implemented in the STB. Moreover, it leads us to speculate that MSTV uses simple ARQ schemes which are sufficient to drastically improve the QoE in the presence of a multitude of loss patterns.