QoS Enhancements for V2X Services in 5G Networks

5G systems (5GS) have been conceived to provide, besides traditional mobile broadband services, also connectivity required by vertical industries, among which Vehicular to Everything (V2X) communication is a prominent example. Enhanced V2X communication extends its reach to safety critical services, which impose severe Quality of Service (QoS) requirements going beyond the capabilities of the early version of 5GS, corresponding to 3GPP release 15 standard specifications. This paper discusses a novel Multi Level QoS (MLQ) feature allowing a tighter QoS monitoring and control, aiming at improving service availability and continuity, essential for safety critical applications. Starting from a review of 3GPP Release 15 QoS model, the paper provides design details for the introduction of MLQ feature in the standard specifications. The paper also provides experimental evaluation of MLQ performance, combining on-field measurements and system level simulations. Results, albeit preliminary, hint to up to two-digit gain in terms of service availability and continuity, at a limited cost both in terms of complexity and additional required signaling.