engleski

Modelling of Network Traffic for Multiplayer Role Playing Games based on User Behaviour

While network traffic characteristics of Massively Multiplayer Online Role-Playing Games (MMORPG) are known to be very variable and somehow linked to game dynamics and user behaviour, the actual relationships have, thus far, not been described in a comprehensive and unified way, which could sucessfully be applied for synthetic traffic generation. This thesis aims to fill this gap by proposing a novel source based MMORPG traffic model, which explains and captures observed variations of traffic characteristics. The proposed model takes user behaviour at the application level as a starting point. As networked virtual worlds of MMORPGs are very complex, there is a wide variety of in-game situations based on “what users do” in the virtual world, which reflect onto network traffic in different ways. The model focuses on capturing, recognizing, understanding, and describing the relationships between user actions and network traffic. A classification proposed in this thesis distinguishes between the following user action categories: Trading, Questing, Player versus player combat, Dungeons, and Raiding. For each action category, a traffic model capturing the statistical characteristics of network traffic has been developed and validated through network traffic measurements. Client and server application protocol data unit size and interrarival time have been modeled by a combination of several distributions, including Weibull, Normal, Lognormal, Largest Extreme Value, and Deterministic. Next, the player behaviour over a sin-gle gaming session has been studied and modelled based on the defined action categories by using a first order Markov chain. Finally, the aggregate behaviour of all active users on a single MMORPG server has been described. The arrival of new players and departure of leaving players are modeled as a Homogeneous Poisson Process (HPP). Based on the proposed model, a functional architecture of a MMORPG traffic generator based on player behaviour, called UrBBaN-Gen, has been developed and implemented by using Java, Python and bash scripts, together with the open source software traffic generator – Distributed Internet Traffic Generator (D-ITG). Synthetic traffic generated by UrBBaN-Gen has been compared with independent empirical traces, and it has been demonstrated that the characteristics of the generated traffic closely follow the real traffic. Also, the model has been compared with the models found in literature, and its advantages over the existing models have been shown. The contribution of this thesis may be summarized as follows:  Classification of user actions in the virtual world of MMORPGs, and characterization of associated network traffic ;  User behaviour model based on categories of user actions, motivational parameters, and identified behavioural patterns on application level ; and  Architecture and implementation of traffic generator based on the model and verification of the model through comparison of synthetic and real traffic.

Network traffic modelling; source network traffic model; communication network; Internet; user behaviour modelling; networked virtual environment; network traffic generation; online game; MMORPG

Disertacija je napisana i obranjena na engleskom jeziku sukladno odluci Fakultetskog vijeća Fakulteta elektrotehnike i računarstva Sveučilišta u Zagrebu. Naziv disertacije na hrvatskom jeziku glasi: "Modeliranje mrežnog prometa višekorisničkih igara s preuzimanjem uloga temeljeno na korisnikovom ponašanju".