Bhojan Anand

Demo: adaptive display power management for mobile games

In this paper, we show how tone mapping techniques can be used to dynamically increase the image brightness, thus allowing the LCD backlight levels to be reduced. This saves significant power as the majority of the LCDs display power is consumed by its backlight. The Gamma function (or equivalent) can be efficiently implemented in smartphones with minimal resource cost. We describe how we overcame the Gamma functions non-linear nature by using adaptive thresholds to apply different Gamma values to images with differing brightness levels. These adaptive thresholds allow us to save significant amounts of power while preserving the image quality. We implemented our solution on a laptop and two Android smartphones. Finally, we present measured analytical results for two different games (Quake III and Planeshift), and user study results (using Quake III and 60 participants) that shows that we can save up to 68% of the display power without significantly affecting the perceived gameplay quality.

Game action based power management for multiplayer online game

Current mobile devices embrace a wide range of functionalities including high speed network support, hardware accelerated 3D graphics, and multimedia capabilities. These capabilities have boosted the interest for enabling multiplayer online games (MOG) support on such devices. However, the lack of similar growth in battery technology limits the usability of these devices for MOGs. In this paper, we present energy conservation techniques for highly interactive MOGs. These are games, such as first-person shooters, where crisp user interaction is paramount to the overall game experience. Hence, conserving energy while preserving crisp user interaction becomes a critical consideration in this domain. We first present three obvious power management approaches and highlight their limitations. We then discuss two application-assisted approaches for power management that manage to save power while preserving the required user experience. Our results demonstrate that these application-assisted approaches are very promising.

ARIVU: Power-aware middleware for multiplayer mobile games

With the improved processing power, graphic quality and high-speed wireless connection in recent generations of mobile phone, it looks more attractive than ever to introduce networked games on these devices. While device features and application resource requirements are rapidly growing, the battery technologies are not growing at the same pace. Networked Mobile games are a class of application, which consume higher levels of energy, as they are naturally more computationally intensive and use hardware components including audio, display and network to their fullest capacities. Therefore, the main concern is the limitation of the battery power of such portable devices to support the potentially long-hour of game play. In this paper we present ARIVU, a power aware middleware that dynamically controls the energy consumption of wireless interface based on the game and system state while maintaining the user experience. ARIVU provides the relevant API for game developers to easily integrate the middleware. We measure power consumption of game play over different wireless interfaces including 3.5G (HSPA), 802.11g and ZigBee. The middleware is able to save up to 40% of the total energy consumed by the wireless interfaces (802.11g and ZigBee). In addition, we show the efficiency of ZigBee interface as potential low power interface for networked game applications.

PARVAI — HVS aware adaptive display power management for mobile games

Displays are one of the major system energy consumers in smartphones. Power consumption of Organic Light-Emitting Diode (OLED) displays have direct relationship with the colour and intensity of the contents being displayed. Games are one of the most popular smartphone applications that consume relatively more resources and power. In this paper, we present Human Visual System (HVS) aware algorithms and techniques to reduce OLED display power consumption up to 45% while retaining the perceived quality of game content. We have implemented and evaluated our solution in the game Quake III and its Android port Kwaak3.

PGTP: Power aware game transport protocol for multi-player mobile games

Applications on the smartphones are able to capitalize on the increasingly advanced hardware to provide a user experience reasonably impressive. However, the advancement of these applications are hindered battery lifetime of the smartphones. The battery technologies have a relatively low growth rate. Applications like mobile multiplayer games are especially power hungry as they maximize the use of the network, display and CPU resources. The PGTP, presented in this paper is aware of both the transport requirement of these multiplayer mobile games and the limitation posed by battery resource. PGTP dynamically controls the transport based on the criticality of game state and the network state to save energy at the wireless network interface (WNIC) level with almost no degradation to the quality of the game play.

Dynamic lookahead mechanism for conserving power in multi-player mobile games

As the current generation of mobile smartphones become more powerful, they are being used to perform more resource intensive tasks making battery lifetime a major bottle-neck. In this paper, we present a technique called dynamic AoV lookahead for reducing wireless interface power consumption upto 50% while playing a popular, yet resource intensive, mobile multiplayer games.

Gamelets — Multiplayer mobile games with distributed micro-clouds

In recent years, cloud computing services have been increasing in greater pace. High penetration rate of mobile devices and resource limited devices escalate the demand for cloud services further [1], [2]. Even though the cloud industry continues to grow exponentially, the cloud gaming service has been left behind due to the limitations in todays technology. There are three well known reasons for the slower growth - latency, server scalability (esp. bandwidth) and lack of game data at client side to use latency hiding and synchronisation techniques such as Dead-reckoning. In this paper, we propose a novel distributed micro-cloud infrastructure with a next generation device called Gamelet to mitigate the limitations in traditional cloud system for multiplayer cloud gaming on resource limited mobile devices. The paper also investigates the opportunities, issues and possible solutions for Gamelet infrastructure for mobile games with a demonstrable prototype.

Game balancing with ecosystem mechanism

To adapt game difficulty upon game characters strength, Dynamic Difficulty Adjustment (DDA) and some other learning strategies have been applied in commercial game designs. However, most of the existing approaches could not ensure diversity in results, and rarely attempted to coordinate content generation and behaviour control together. This paper suggests a solution that is based on multi-level swarm model and ecosystem mechanism, in order to provide a more flexible way of game balance control.

CloudHide: Towards Latency Hiding Techniques for Thin-client Cloud Gaming

Though there is an explosion of cloud services in recent years, cloud gaming industry is still way behind in making a strong breakthrough. Despite many benefits of cloud gaming (video or pixel streaming of rendered game scenes), the primary factor that hinders the growth is response latency, a well known issue. In this paper, we introduce a novel predictive paradigm of cloud gaming in order to mitigate latency that is inherent in cloud gaming systems. The main idea of the predictive paradigm is to pre-generate and send future outcome frames in advance to the thin-client so that the thin-client can respond immediately to any user input. The approach in this work seeks to exploit the near unlimited processing power of the cloud and ever increasing network bandwidth. The paper provides a generic and comprehensive theoretical model that shows the relationship between various parameters (network bandwidth, round-trip-time and processing time for game logic, predicting future outcomes, rendering, capturing, encoding and decoding) of predictive cloud gaming and response latency. The theocratical model design is started with an ideal server with unlimited resources for ease of understanding and then it is enhanced with resource constraints of a practically feasible non-ideal server. The model demonstrates significant amount of response latency reduction in predictive cloud gaming when compared to conventional cloud gaming. The model is analysed further to estimate the resource requirements for predictive cloud gaming. A simple game is built to demonstrate key aspects of the model and to conduct subjective evaluation of quality of experience (QoE) of the game play. The evaluations show significant gain in QoE. The resource requirements of the predictive cloud gaming gaming system grows exponentially with respect to prediction period of future frames. The paper illustrates some optimisation methods to reduce exponential growth and discusses directions for further works in this area.

Report of HotMobile 2010

HotMobile is SIGMOBILEs highly selective, interactive workshop focused on mobile applications, systems, and environments, as well as their underlying state-of-the-art technologies. Themes from this years workshop were mobile and urban computing, security, privacy, and sensing.