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Optimizing Background Email Sync on Smartphones
"... Email is a key application used on smartphones. Even when the phone is in stand-by mode, users expect the phone to continue syncing with an email server to receive new messages. Each such sync operation wakes up the smartphone for data reception and processing. In this paper, we show that this “cost ..."
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Email is a key application used on smartphones. Even when the phone is in stand-by mode, users expect the phone to continue syncing with an email server to receive new messages. Each such sync operation wakes up the smartphone for data reception and processing. In this paper, we show that this “cost of email sync ” in stand-by mode constitutes a significant source of energy consumption, and thus reduces battery life. We quantify the power performance of different existing email clients on two smartphone platforms, Android and Windows Phone, and study the impact of system parameters such as email size, inbox size, and pull vs. push. Our results show that existing email clients do not handle email sync in an energy efficient way. This is because the underlying protocols and architectures are not designed for the specific needs of operating in stand-by mode. Based on our findings, we derive general design principles for energyefficient event handling on smartphones, and apply these principles to the case of email sync and implement our techniques on commercial smartphones. Experimental results show that our techniques are able to significantly reduce energy cost of email sync by 49.9 % on average with our experiment settings.
1Code-Based Neighbor Discovery Protocols In Mobile Wireless Networks
"... Abstract—In mobile wireless networks, the emerging proximity-based applications have led to the need for highly effective and energy-efficient neighbor discovery protocols. However, existing works cannot realize the optimal worst-case latency in symmetric case, and their performances with asymmetric ..."
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Abstract—In mobile wireless networks, the emerging proximity-based applications have led to the need for highly effective and energy-efficient neighbor discovery protocols. However, existing works cannot realize the optimal worst-case latency in symmetric case, and their performances with asymmetric duty cycles can still be improved. In this work, we investigate asynchronous neighbor discovery through a code-based approach, including the symmetric and asymmetric cases. We derive the tight worst-case latency bound in the case of symmetric duty cycle. We design a novel class of symmetric patterns called Diff-Codes, which is optimal when the Diff-Code can be extended from a perfect difference set. We further consider the asymmetric case, and design ADiff-Codes. To evaluate (A)Diff-Codes, we conduct both simulations and testbed experiments. Both simulation and experiment results show that (A)Diff-Codes significantly outperform existing neighbor discovery protocols in both the median case and worst-case. Specifically, in the symmetric case, the maximum worst-case improvement is up to 50%; in both symmetric and asymmetric cases, the median case gain is as high as 30%.
Watts2Share: Energy-Aware Traffic Consolidation
"... Abstract—Energy consumption is becoming the Achilles ’ heel of the mobile user quality of experience partly due to undisciplined use of the cellular (3G) transmissions by applications. The operator infrastructure is typically configured for peak performance, whereas during periods of underutilisatio ..."
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Abstract—Energy consumption is becoming the Achilles ’ heel of the mobile user quality of experience partly due to undisciplined use of the cellular (3G) transmissions by applications. The operator infrastructure is typically configured for peak performance, whereas during periods of underutilisation the handsets pay the price by staying in high energy states even if each application only uses a fraction of the maximum available bandwidth. In this paper we promote a bi-radio scenario where instead of independently using own cellular connections, several users share a single cellular link offered by one member of a coalition (a rotating aggregator). We present Watts2Share, an architecture for energy-aware traffic consolidation whereby group members’ data flows transmitted through a second radio (e.g., WiFi) are aggregated by the aggregator and retransmitted through the cellular link. Through careful and repeatable studies we demonstrate that this scheme saves up to 68 % of the total transmission energy in handsets compared to a pure 3G scenario. The studies are based on a wide range of real traffic traces and real cellular operator settings, and further illustrate that this scheme reduces the overall energy by reducing the signalling overhead, as well as extending the lifetime of all handsets. Index Terms—traffic consolidation; bandwidth sharing; 3G; WiFi; SoftAP;
Exploiting ZigBee in Reducing WiFi Power Consumption for Mobile Devices
, 2013
"... Abstract—We present HoWiES, a system that saves energy consumed by WiFi interfaces in mobile devices with the assistance of ZigBee radios. The core component of HoWiES is a WiFi-ZigBee message delivery scheme that enables WiFi radios to convey different messages to ZigBee radios in mobile devices. B ..."
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Abstract—We present HoWiES, a system that saves energy consumed by WiFi interfaces in mobile devices with the assistance of ZigBee radios. The core component of HoWiES is a WiFi-ZigBee message delivery scheme that enables WiFi radios to convey different messages to ZigBee radios in mobile devices. Based on the WiFi-ZigBee message delivery scheme, we design three protocols that target three WiFi energy saving opportunities in scanning, standby and wakeup respectively. We have implemented the HoWiES system with two mobile devices platforms and two AP platforms. Our real-world experimental evaluation shows that our system can convey thousands of different messages fromWiFi radios to ZigBee radios with an accuracy over 98 percent, and our energy saving protocols, while maintaining the comparable wakeup delay to that of the standard 802.11 power save mode, save 88 and 85 percent of energy consumed in scanning state and standby state respectively. Index Terms—WiFi, 802.11, energy savings, ZigBee, 802.15.4, mobile devices Ç 1
Model-Driven Energy-Aware Rate Adaptation
"... Rate adaptation in WiFi networks has received significant attention recently. However, most existing work focuses on selecting the rate to maximize throughput. How to select a data rate to minimize energy consumption is an important yet under-explored topic. This problem is becoming increasingly imp ..."
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Rate adaptation in WiFi networks has received significant attention recently. However, most existing work focuses on selecting the rate to maximize throughput. How to select a data rate to minimize energy consumption is an important yet under-explored topic. This problem is becoming increasingly important with the rapidly increasing popularity of MIMO deployment, because MIMO offers diverse rate choices (e.g., the number of antennas, the number of streams, modulation, and FEC coding) and selecting the appropriate rate has significant impact on power consumption. In this paper, we first use extensive measurement to develop a simple yet accurate energy model for 802.11n wireless cards. Then we use the models to drive the design of an energy-aware rate adaptation scheme. A major benefit of a model-based rate adaptation is that applying a model allows us to eliminate frequent probes in many existing rate adaptation schemes so that it can quickly converge to the appropriate data rate. We demonstrate the effectiveness of our approach using trace-driven simulation and real implementation in a wireless testbed.
Performance Evaluation of Mobile Hotspots in Densely Deployed WLAN Environments
"... Abstract—This paper presents a study of mobile wireless LAN (WLAN) hotspots which are used to provide cellular-WiFi tethering service to personal devices. A dense deployment scenario for fixed and mobile WLAN is described and potential performance problems due to interference are identified. An anal ..."
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Abstract—This paper presents a study of mobile wireless LAN (WLAN) hotspots which are used to provide cellular-WiFi tethering service to personal devices. A dense deployment scenario for fixed and mobile WLAN is described and potential performance problems due to interference are identified. An analytical model for coexisting fixed and mobile WLAN hotspots with heterogeneous traffic is presented. The model is used to evaluate the performance of a mobile WLAN as it transits through a set of densely deployed fixed access points (APs), and performance problems due to lack of frequency coordination are identified. An adaptive channel assignment (ACA) scheme for improving mobile AP performance is proposed and evaluated. It is shown that significant performance gains can be achieved with ACA with maximum absolute and percentage throughput gains up to 1.24 Mbps and 42.8 % respectively. We also show that setting the scanning interval in ACA requires consideration of the speed at which the mobile WLAN is moving in order to compensate for the throughput losses during channel scanning. Index Terms—adaptive channel assignment, hotspots, mobile WLAN, WiFi tethering. I.
Physical Media Covert Channels on Smart Mobile Devices
"... In recent years mobile smart devices such as tablets and smartphones have exploded in popularity. We are now in a world of ubiquitous smart devices that people rely on daily and carry everywhere. This is a fundamental shift for com-puting in two ways. Firstly, users increasingly place unprece-dented ..."
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In recent years mobile smart devices such as tablets and smartphones have exploded in popularity. We are now in a world of ubiquitous smart devices that people rely on daily and carry everywhere. This is a fundamental shift for com-puting in two ways. Firstly, users increasingly place unprece-dented amounts of sensitive information on these devices, which paints a precarious picture. Secondly, these devices commonly carry many physical world interfaces. In this pa-per, we propose information leakage malware, specifically designed for mobile devices, which uses covert channels over physical “real-world ” media, such as sound or light. This malware is stealthy; able to circumvent current, and even state-of-the-art defenses to enable attacks including privilege escalation, and information leakage. We go on to present a defense mechanism, which balances security with usability to stop these attacks.
Mobile Wi-Fi Hotspot Cooperation Towards Better Energy Efficiency
"... Abstract—Power consumption has become a primary concern for mobile phone users in the past few years. This paper focuses on a common scenario, where cellular network is the only option to access the Internet for a number of mobile phones, e.g. because of overcrowded Wi-Fi access (in lecture halls). ..."
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Abstract—Power consumption has become a primary concern for mobile phone users in the past few years. This paper focuses on a common scenario, where cellular network is the only option to access the Internet for a number of mobile phones, e.g. because of overcrowded Wi-Fi access (in lecture halls). Compared with cellular data transmission, Wi-Fi transmission is significantly more energy-efficient. Thus, we propose to utilize Wi-Fi tethering technique to optimize the overall power consumption. For that purpose, cooperation among users is fundamental. A certain number of mobile phones are selected to act as Wi-Fi hotspot nodes, while the rest act as dumb Wi-Fi nodes. We make two main contributions. Firstly, based on a series of measurements, we find out principles of choosing appropriate mobile Wi-Fi hotspot nodes, i.e., selecting the ones with reasonable 3G signal strength, sufficient battery capacity and good Wi-Fi coverage, while making use of the 3G bandwidth of the hotspot nodes as much as possible. Secondly, we propose cooperation two algo-rithms to optimize the overall power consumption. Simulation results demonstrate that our algorithms can achieve up to 29% power saving compared with normal 3G approach. I.
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"... e ene mmu sation exp knowledge about current services we show that the scheme can achieve energy savings he fa n mo ation Several major works focus on reducing the energy foot-print of the infrastructure nodes (e.g., [1–3]), which by y resources. From can be ac rdware an but also so residing in tran ..."
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e ene mmu sation exp knowledge about current services we show that the scheme can achieve energy savings he fa n mo ation Several major works focus on reducing the energy foot-print of the infrastructure nodes (e.g., [1–3]), which by y resources. From can be ac rdware an but also so residing in transport and application/session laye development, flow management). While vendo continuously reduce the hardware footprint they optimise energy at packet/flow level since the device is application agnostic. This paper focuses on the communica-tion energy optimisation at the device level. Other energy saving measures managed within the infrastructure
Web API Energy efficiency Transfer size reduction
, 2013
"... Abstract Recently, the proliferation of smartphones and the extensive coverage of wireless networks have enabled numerous mobile users to access Web resources with smartphones. Mobile mashup applications are very attrac-tive to smartphone users due to specialized services and user-friendly GUIs. How ..."
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Abstract Recently, the proliferation of smartphones and the extensive coverage of wireless networks have enabled numerous mobile users to access Web resources with smartphones. Mobile mashup applications are very attrac-tive to smartphone users due to specialized services and user-friendly GUIs. However, to offer new services through the integration of Web resources via Web API invocations, mobile mashup applications suffer from high energy consumption and long response time. In this paper, we propose a proxy system and two techniques to reduce the size of data transfer, thereby enabling mobile mashup applications to achieve energy-efficient and cost-effective Web API invocations. Specifically, we design an API query language that allows mobile mashup applications to readily specify and obtain desired information by instructing a proxy to filter unnecessary information returned from Web API servers. We also devise an image multi-get module, which results in mobile mashup applications with smaller transfer sizes by combining multiple images and adjusting the quality, scale, or resolution of the images. With the proposed proxy and techniques, a mobile mashup appli-cation can rapidly retrieve Web resources via Web API invocations with lower energy consumption due to a smaller number of HTTP requests and responses as well as smaller response bodies. Experimental results show that the proposed proxy system and techniques significantly reduce transfer size, response time, and energy consumption of mobile mashup applications.
