Novel solutions are required to meet the stringent reliability and latency requirements targeted for the Ultra Reliable Low Latency Communication service class, which emerged with the introduction of 5G new radio. This paper analyses reliability-oriented multi-Connectivity-where the same data packet is independently transmitted through multiple links-as such a solution. Multi-connectivity is first presented at a conceptual level. We then propose a novel admission mechanism to control the number of users operating in multi-connectivity mode. Finally, the reliability and latency enhancement with multi-connectivity in heterogeneous network scenario with multi-service traffic is evaluated via system level simulation. Up to 23% latency reduction and 57% reliability improvements over the single connectivity solution are observed. However such gains are sensitive to the configuration criteria, and the average gains are more modest.

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Cellular networks based on current LTE Advanced or coming 5G technology, constitute an attractive candidate to provide communication links for drones in low level airspace. This paper extends previous findings on path loss exponent and shadow fading variation for an urban environment, by adding new and more extensive empirical evidence. Specifically, by way of the measurement methodology we study also the spatial correlation of the shadow fading, including the lateral spatial autocorrelation (decorrelation distance) and the crosscorrelation in shadowing variability between different heights. Data was obtained with the use of a drone flying at heights up to and above rooftop, using a radio network scanner for measuring live LTE signals at 1800 MHz. The path loss analysis confirmed the validity of previously presented modelling frameworks for the behaviour versus height, as well as the characteristics of the increased interference observed when the drone is above rooftop level. As for the spatial correlation of the shadow fading, the results indicate that decorrelation distance does not change appreciably from ground level up to and above rooftop level, and remains in the order of 10m. The shadow fading variability is generally uncorrelated versus height, although with a trend to be correlated below rooftop level, but not above.

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