Interactive online game applications require connectivity between the game application client and a game application server. The game application client typically runs on a UE or on a device attached to a UE. The type of traffic generated depends on the type of game. The Quality of Experience is influenced by the adequacy of the QoS of the connectivity and the traffic requirements from the game application. For example, Ref. [23] provides delay thresholds per game type in Table A-1:

Cloud gaming implies that, while the game is being played by a user on a client, game application processing and rendering is totally or partly performed in a remote network entity, potentially at the edge of the network. The rendered 2D or VR360 video is then encoded and streamed to the client. These extra steps in game workflow influence the overall interactive delay and audio/video quality (e.g. encoding type/profile/level and performances, resolution and frame rate), and hence influence the Quality of Experience. There is work in ITU-T Study Group 12 regarding assessment of gaming quality. Two recommendations are published:

• ITU-T G.1032 "Influence factors on gaming quality of experience" (https://www.itu.int/rec/T-REC-G.1032-201710-I/en) [38]
• ITU-T P.809 "Subjective evaluation methods for gaming quality" (https://www.itu.int/rec/T-REC-P.809/en). [39]

This last recommendation could be used to produce comparable subjective evaluations of the influence of connectivity characteristics over QoE. Clause 5.3.1 of TR 22.842 discusses cloud gaming requirements. It states that "Taking out the delay for rendering and encoding/decoding processing, the round-trip time (RTT) delay over 5GS should be less than 5 ms". Cloud gaming services already exist, and new ones are being launched, enabling users to play any type of game (whether it is originally offline or online, single player or multiplayer etc.) on a device like a lite smartphone, tablet or TV which would typically be unable to process such a game. The following is a brief look at several of these services and the public information about their requirements. Cloud gaming typical traffic characteristics are evolving as services are being deployed. But a tendency can be derived from the data available. Bitrates in the range of 5-35Mbps are expected. Although latency requirements vary from game types and users, cloud gaming services are expected to offer a Quality of Experience which is at least as good as the experience of regular (locally processed) gaming.