Dario Gallucci

Traffic Prioritization of H.264/SVC Video over 802.11e Ad Hoc Wireless Networks

The H.264/SVC video codec extends the H.264/AVC standard with scalability features. In this paper we introduce a traffic prioritization algorithm suitable for the transmission of both H.264/SVC and H.264/AVC video over 802.11e ad hoc wireless networks. The proposed algorithm exploits the traffic prioritization capabilities offered by 802.11e to provide better protection to the most perceptually important parts of a video while achieving efficient network resource usage. We evaluate the algorithm by simulating video transmissions in an ad hoc network scenario. Results show that the H.264/SVC codec particularly benefits from the proposed algorithm, which enables a graceful video quality degradation in congested network conditions, as well as PSNR gains up to 2 dB with respect to the H.264/AVC codec using the same amount of network resources.

Detecting energy leaks in Android app with POEM

This paper presents the design and implementation of a Portable Open Source Energy Monitor (POEM) to enable developers to automatically test and measure the energy consumption of every single application component down to the control flow level. Based on existing portable power meter designs, POEM extends the state of the art of application analysxis with the energy annotation of the control flow down to the basic blocks, the call graph, and the Android API calls, allowing developers to locate energy leaks in their applications with high accuracy. Because the power consumption is tied to the system status, energy annotation is also coupled with system activities.

Content-adaptive traffic prioritization of spatio-temporal scalable video for robust communications over QoS-provisioned 802.11e networks

In this work a low complexity traffic prioritization strategy to transmit H.264 scalable video coding (SVC) video over 802.11e wireless networks is presented (the approach applies to any DiffServ-like network). The distinguishing feature of the proposed strategy is the ability to adapt the amount of error protection to the changing characteristics of the video content. First, we estimate the perceptual impact of data losses in the different types of enhancement layers, i.e., temporal or spatial, for a large set of H.264/SVC videos. The experiments show that perceptual impairments are highly correlated with the level of motion activity in the video sequence. Then, we propose a content-adaptive traffic prioritization strategy based on the identification of the most important parts of the enhancement layers of the video sequence by means of a low complexity macroblock analysis process. The prioritization algorithm is tested by simulating a realistic 802.11e ad hoc network scenario. Simulation results show that the proposed traffic prioritization strategy consistently outperforms, particularly for dynamic video sequences, fixed a priori approaches, as well as a traditional FEC-based UEP strategy.

High-Performance H.264/SVC Video Communications in 802.11e Ad Hoc Networks

This work focuses on improving the performance of video communications based on the recently developed H.264 Scalable Video Coding (SVC) standard over 802.11e wireless networks. The H.264/SVC standard is particularly suitable for wireless communications because of its compression efficiency and the ability to adapt to different network scenarios. The adoption of the H.264/SVC codec in 802.11 networks poses however some issues. In particular, since pictures are encoded into several small video units, the overhead imposed by the 802.11 contention-based channel access mechanism might be large. Thus, the strategy employed for the packetization of the video data plays a key role in determining the performance of the network. This work proposes two network adaptation strategies for H.264/SVC video to efficiently use the QoS-enabled 802.11e extension of the 802.11 standard by designing a scheme for joint optimization of video data aggregation and unequal error protection. Simulations of video transmissions in a realistic home networking scenario characterized by direct communications between devices in ad hoc mode show that the proposed strategies reduce the packet loss rate and significantly improve the quality of the communication with PSNR gains up to about 2 dB. Moreover, the performance of the proposed low-complexity strategy is close to that of the optimal, high-complexity, strategy.

Content-Adaptive Robust H.264/SVC Video Communications over 802.11e Networks

In this paper we present a low-complexity traffic prioritization strategy for video transmission using the H.264 scalable video coding (SVC) standard over 802.11e wireless networks.The first part of this work focuses on assessing the perceptual impact of data loss in the various enhancement layers using a wide set of H.264/SVC encoded videos.The analysis shows that perceptual impairments are highly correlated with the motion activity in the video sequence.Thus, we propose an adaptive unequal error protection strategy which identifies the most perceptually important parts of the enhancement layers in the video sequence by means of a low complexity macroblock motion analysis process.The algorithm is tested by simulating a realistic 802.11e based home network scenario.Results obtained on a large set of video sequences show that the proposed content-aware traffic prioritization strategy enables PSNR gains up to 2.5 dB as well as noticeable visual quality improvements with respect to a traditional prioritization strategy aiming at minimizing error propagation.

Modeling Social Interactions in Real Work Environments

We present a study for modeling the behavioral patterns of employees and keeping track of the social interactions among people in a real work environment. The main advantage of our approach to capture social interactions in a work environment is the use of off-the-shelf tools and devices - like smartphones available on the market - and the utilization of the discovered patterns for the optimum distribution of employees in a office building. We carried out an experiment in our building at Fernfachhochschule Schweiz and captured data about physical proximity, virtual interactions (i.e., email exchange) and individual performance satisfaction of 20 employees for 8 working days, during their working hours. The objective of the experiment was to investigate the interaction patterns of employees in relation to four aspects: quantity, space, performance and organization. Besides confirming the existence of different social interaction types, we also provide insights in how distance between office spaces affects type and amount of social interaction. Further, we describe the influence of contacts among workers on their performance. Finally, our analysis emphasizes the importance of an employees role in terms of number of physical and virtual interactions.

A Hybrid method for testing routing protocols in mesh networks

Abstract This article presents a hybrid method for testing routing protocols specifically dedicated to mesh networks. The architecture of software routers is described and a graphic environment that would ensure effective configuration of test networks is proposed. The platform for tests of routing protocols presented in the article combines an implementation of routing protocols (the real control plane) with a router data plane simulator. The proposed solution provides an opportunity to test real implementations of routing protocols for any parameters of data plane, not limited by the physical implementation of a test network. The presented platform is based on an open source code

User-profiled platform with advanced navigation support

The increasing spreading of top-medium range mobile phones offering advanced capabilities and the broader use of short-range wireless technologies embedded in them are laying the foundations for the development of new added-value services. In this paper we present an architectural solution for delivering location-based services over heterogeneous mobile phones tailored to the preferences of individual users. We then discuss the performance of a solution for proximity marketing derived from the platform, in terms of localization accuracy and client-application usability.

QoS enabled mobility support for mesh networks

Existing solutions for building wireless mesh networks suffer from reduced efficiency. This is due to lack of reliable self-configuration procedures that can dynamically adapt to varying network conditions, lack of efficient and scalable end-to-end Quality of Service (QoS) support, and lack of generalized and seamless mobility support. Therefore, ensuring a certain level of QoS to mobile users is one of the most crucial challenges, and it is clearly one of the major inhibitors to the commercial success of mesh networks. In this paper, we present a heuristic service classification approach and a correspondent traffic classification algorithm for handling the multimedia traffic at the network and the application layer, in order to better characterize the traffic. The preliminary simulation results show that the approach is able to classify a large part of the traffic and, consequently, to handle it appropriately. This is confirmed by the encouraging preliminary results where the worst case is managed fairly in comparison to the average case.