Why Latency Matters to Mobile Backhaul - O3b Networks

Why Latency Matters to Mobile BackhaulMobile Service ClassificationFrom a mobile network perspective, the ITU and the 3GPP have groupedthe end-user services into four classes based on their sensitivity to latency.Figure 4 – User services classificationThis paper focuses on the three major service classes for mobile operatorsand the practical impact of latency on:− Conversational Voice− Interactive Applications, such as cloud-based applications, onlineshopping, instant messenger and online search.− Non real-time data, such as web browsing, email SMS/Text messaging,file sharing, and video streaming.Conversational Voice ServicesVoice quality is measured in the ITU model by the R factor, which can alsobe translated into a Mean Opinion Score (MOS) score, a scale widely usedto evaluate the quality of a voice call. The MOS score and voice call qualitydegrades rapidly when the ear-to-mouth latency increases beyond 200ms.Annex 1 provides a detailed explanation of the ITU model.A latency comparison for a UMTS Release 99 voice call for two cases usingMEO and GEO satellites is shown below.Figure 5 – End to end latency distribution for a voice call with O3b satellite backhaulwww.o3bnetworks.com 7