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Summary:
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This Technical Report describes a framework and methodology for a spatially resolved single-number indicator expressing mobile network usefulness for a given range of purposes. The spatial resolution can be adjusted, by respective aggregation; practical ranges start at 25 to 50 m depending on the quality of GNSS data. The spectrum of purposes includes single-network assessment (e.g., expected speech quality or call stability) as well as assessment of coverage for emergency calls, where coverage of multiple networks is combined into a single indicator.
Single-number indicators are used in QoS and QoE contexts to express an overall assessment of a system or service from a given perspective. Such indicators are used routinely, e.g., in mobile network benchmarking, where a number of QoS KPI is aggregated towards a single rating. This Technical Report describes a methodology which works in the same way, but is using low-level measurement data, i.e., RF level values. The particular instance, i.e., the actual type of input value, depends on the radio network technology, e.g., RxLev for 2G, RSCP for 3G and RSRP for 4G and 5G, respectively.
The indicator which is the result of data processing expresses a quantity from the QoS domain, namely the usefulness of the network coverage for a given range of purposes. The algorithm uses mapping relations which link the input quantity to component quantities from the QoS domain, such as telephony call setup success, call stability or call quality, or respective QoS KPI for packet-data services. These mapping relations are typically created from empirical data, e.g. from analysis of sufficiently large amounts of actual measurement data.
It is understood that the respective indicator does not assume the same level of accuracy or relevance as a primary QoS quantity from active measurements. The degree of prediction accuracy will depend on input data available for respective characteristic curves, e.g., visualized by a scatter plot, or a heatmap-style density visualization. The indicator is however providing additional value in situations where only data from passive measurements, i.e., measurement of said RF levels, is available, or to create additional insights from data produced otherwise. It is meant to work with diverse data sources, such as RF level values provided from industrial-grade testing tools, apps, RF scanners, and even crowdsourcing.
It is important to understand that this Technical Report does not attempt to provide actual fixed numbers, target values, thresholds or concrete mapping functions, as such absolute relations would not reflect the diversity of applications and situations in mobile network operation worldwide. Rather, it provides a solid methodological framework to create such implementations, as well as accompanying guidance and considerations on reliability of data in relation to properties of data sources.
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