Monitoring Energy Consumption of Smartphones

With the rapid development of new and innovative applications for mobile devices like smartphones, advances in battery technology have not kept pace with rapidly growing energy demands. Thus energy consumption has become a more and more important issue of mobile devices. To meet the requirements of saving energy, it is critical to monitor and analyze the energy consumption of applications on smartphones. For this purpose, we develop a smart energy monitoring system called SEMO for smartphones using Android operating system. It can profile mobile applications with battery usage information, which is vital for both developers and users.Comment: The 1st International Workshop on Sensing, Networking, and Computing with Smartphones (PhoneCom), IEEE, Dalian, China, Oct 19-22, 201

Modelagem Multiagentes de uma Infraestrutura Descentralizada para Aprendizagem Ubíqua

GLOBAL é uma infraestrutura descentralizada para ambientes de aprendizagem ubíqua, baseada em agentes de software. A partir da extensão dos seus agentes ou adição de novos, a infraestrutura pode ser especializada para a criação de ambientes de aprendizagem ubíqua. Este artigo contribui apresentando a modelagem da infraestrutura através de uma metodologia multiagentes. Nesse trabalho, GLOBAL foi completamente modelada usando a metodologia Prometheus. Além disso, o artigo discute como os agentes foram implementados e como foram integrados a um sistema dedicado à colaboração em ambientes de aprendizagem ubíqua

Análisis y procesado de medidas de parámetros de banda estrecha utilizando un smartphone con sistema operativo Android

La medición de los parámetros de RF en las redes celulares es de suma importancia para la caracterización del canal de banda estrecha. Para el mejor conocimiento, no existe ninguna aplicación Android test drive disponible actualmente que captura los parámetros de la señal de RF a lo largo de un camino. Por consiguiente, hemos programado una aplicación Android para smartphones que mide la potencia de RF recibida a lo largo de un camino. Esta aplicación calcula la posición del teléfono inteligente utilizando las coordenadas geográficas proporcionadas por el GPS. También calculamos la distancia aproximada entre la estación base y el teléfono inteligente con la base de datos de las estaciones base proporcionadas por Google. Por último, se ha realizado una campaña de medidas en calles anchas y calles estrechas de la ciudad de Valencia. Y asi, hemos obtenido el exponente de propagación y la desviación estándar de shadowing para ambos ambientes.The measurement of RF parameters in cellular networks is of paramount importance for the characterization of the narrowband channel. To the author best knowledge, no Android test drive application is currently available which captures RF signal parameters along a path. Therefore we have programmed an Android application for smartphones which measures RF power received along a path. This application calculates the position of the smartphone by using the geographic coordinates provided by its GPS. We also estimate the distance between the base station and the smartphone with the base station data base location from Google. Finally, a simple measurement campaign has been carried out in both wide streets and narrow streets of Valencia. Thus, we have obtained the propagation exponent and the standard deviation of the shadowing for both environments.Carrillo Padilla, WR. (2013). Análisis y procesado de medidas de parámetros de banda estrecha utilizando un smartphone con sistema operativo Android. http://hdl.handle.net/10251/35013.Archivo delegad

Open source software GitHub ecosystem: a SEM approach

Open source software (OSS) is a collaborative effort. Getting affordable high-quality software with less probability of errors or fails is not far away. Thousands of open-source projects (termed repos) are alternatives to proprietary software development. More than two-thirds of companies are contributing to open source. Open source technologies like OpenStack, Docker and KVM are being used to build the next generation of digital infrastructure. An iconic example of OSS is 'GitHub' - a successful social site. GitHub is a hosting platform that host repositories (repos) based on the Git version control system. GitHub is a knowledge-based workspace. It has several features that facilitate user communication and work integration. Through this thesis I employ data extracted from GitHub, and seek to better understand the OSS ecosystem, and to what extent each of its deployed elements affects the successful development of the OSS ecosystem. In addition, I investigate a repo's growth over different time periods to test the changing behavior of the repo. From our observations developers do not follow one development methodology when developing, and growing their project, and such developers tend to cherry-pick from differing available software methodologies. GitHub API remains the main OSS location engaged to extract the metadata for this thesis's research. This extraction process is time-consuming - due to restrictive access limitations (even with authentication). I apply Structure Equation Modelling (termed SEM) to investigate the relative path relationships between the GitHub- deployed OSS elements, and I determine the path strength contributions of each element to determine the OSS repo's activity level. SEM is a multivariate statistical analysis technique used to analyze structural relationships. This technique is the combination of factor analysis and multiple regression analysis. It is used to analyze the structural relationship between measured variables and/or latent constructs. This thesis bridges the research gap around longitude OSS studies. It engages large sample-size OSS repo metadata sets, data-quality control, and multiple programming language comparisons. Querying GitHub is not direct (nor simple) yet querying for all valid repos remains important - as sometimes illegal, or unrepresentative outlier repos (which may even be quite popular) do arise, and these then need to be removed from each initial OSS's language-specific metadata set. Eight top GitHub programming languages, (selected as the most forked repos) are separately engaged in this thesis's research. This thesis observes these eight metadata sets of GitHub repos. Over time, it measures the different repo contributions of the deployed elements of each metadata set. The number of stars-provided to the repo delivers a weaker contribution to its software development processes. Sometimes forks work against the repo's progress by generating very minor negative total effects into its commit (activity) level, and by sometimes diluting the focus of the repo's software development strategies. Here, a fork may generate new ideas, create a new repo, and then draw some original repo developers off into this new software development direction, thus retarding the original repo's commit (activity) level progression. Multiple intermittent and minor version releases exert lesser GitHub JavaScript repo commit (or activity) changes because they often involve only slight OSS improvements, and because they only require minimal commit/commits contributions. More commit(s) also bring more changes to documentation, and again the GitHub OSS repo's commit (activity) level rises. There are both direct and indirect drivers of the repo's OSS activity. Pulls and commits are the strongest drivers. This suggests creating higher levels of pull requests is likely a preferred prime target consideration for the repo creator's core team of developers. This study offers a big data direction for future work. It allows for the deployment of more sophisticated statistical comparison techniques. It offers further indications around the internal and broad relationships that likely exist between GitHub's OSS big data. Its data extraction ideas suggest a link through to business/consumer consumption, and possibly how these may be connected using improved repo search algorithms that release individual business value components

Reducing Energy Consumption of a Modem via Selective Packet Transmission Delaying

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2017. 2. 홍성수.스마트폰을 비롯한 생활 밀착형 모바일 장치에서 모뎀이 소모하는 전력량을 줄이고자 하는 노력들이 끊임없이 경주되고 있다. 이러한 모뎀의 전력 소모량 절감 방안에 대한 연구들은 주로 패킷 전송 지연 기법에 기반한다. 패킷 전송 지연 기법이란 모바일 장치에서 지연 전송이 가능한 패킷의 전송 요청이 발생하는 경우, 해당 패킷의 전송을 지연시켰다가 이후에 전송 요청된 패킷들과 함께 한 번에 전송하는 기법이다. 이 기법은 모뎀이 여러 개의 패킷을 긴 시간에 걸쳐 산발적으로 전송하는 것에 비해서, 같은 패킷들을 짧은 시간 동안 한꺼번에 전송할 때 훨씬 적은 양의 전력을 소모하는 특성을 가지고 있다는 점에 착안하여 개발된 기법이다. 기존 연구들은 패킷 전송 지연 기법을 모바일 장치의 다양한 동작 상황에서 효과적으로 적용하는 각기 다른 방안들을 제시한다. 그러나 스마트폰과 같은 최신 모바일 장치의 복잡한 동작 환경에서 모뎀의 무선 자원 제어 상태를 치밀하게 고려하지 않고 적용하는 패킷 전송 지연 기법은 오히려 예기치 못한 추가적인 전력 소모를 야기하기도 한다. 이 문제는 기존의 모뎀 전력 소모량 절감 기법들의 효용성을 크게 해침으로써 실제 산업에 적용되기 어렵게 만든다. 본 학위논문에서는 앞서 설명한 문제를 해결하기 위해 선별적 패킷 전송 지연 기법을 제안한다. 제안하는 기법은 패킷 전송을 지연한 결과로 모뎀의 전력 소모량이 줄어들 것으로 예상될 때에만 선별적으로 패킷 전송을 지연한다. 이 기법의 핵심 골자는 패킷 전송 지연에 따른 전력량 이득 추산 모델이다. 이 모델은 모바일 장치에서 어떤 패킷의 전송 요청이 발생했을 때, 해당 시점의 모뎀의 무선 자원 제어 상태와 다음 번 패킷 전송 요청의 예상 발생 시점을 사용하여, 해당 패킷을 지연 전송하는 경우 모뎀의 전력 소모량이 어떻게 변화할지를 계산하는 모델이다. 제안하는 선별적 패킷 전송 지연 기법은 세 개의 핵심 컴포넌트들로 구성된다. 첫 번째는 지연 가능 패킷 판별기(Deferrable Packet Identifier)이다. 이 컴포넌트는 패킷 전송 요청이 발생했을 때, 해당 패킷의 전송 지연을 모바일 장치의 사용자가 인지할 수 있는지 여부를 사용하여 그 패킷의 지연 가능 여부를 판단한다. 두 번째는 패턴 기반 다음 패킷 예측기(Pattern-based Next Packet Predictor)이다. 이 컴포넌트는 사전 학습 단계와 온라인 적용 단계로 나누어 동작한다. 먼저 사전 학습 단계에서는 모바일 장치에서 수행되는 응용들의 패킷 전송 요청들을 모니터링하고, 이를 통해 각 응용의 패킷 전송 요청 패턴들을 도출한다. 이후 온라인 적용 단계에서는 도출된 패턴들을 사용하여 모바일 장치에서 다음 패킷 전송 요청이 언제 발생할지를 예측한다. 마지막 컴포넌트는 패킷 전송 시점 결정기(Packet Transmission Time Designator)이다. 이 컴포넌트는 패킷 전송 요청이 발생했을 때, 앞서 언급한 두 컴포넌트의 수행 결과와 패킷 전송 지연에 따른 전력량 이득 추산 모델을 사용하여 최종적으로 모뎀의 전력 소모량이 절감되도록 해당 패킷의 실제 전송 시점을 결정한다. 본 연구에서 제안한 기법의 효용성을 검증하기 위해서 실제 이동통신 네트워크망에 연결된 상용 스마트폰을 사용하여 다양한 실험을 수행하였다. 구체적으로, KT의 4세대 LTE 네트워크 망에 연결된 Google Nexus 5 스마트폰에 앞서 설명한 세 가지 핵심 컴포넌트들을 구현하고 실험적으로 모뎀의 전력 소모량 절감 효과를 평가하였다. 실험 결과, 제안된 기법을 적용함으로써 모뎀의 전력 소모량이 최대 22.5% 줄어드는 것을 확인하였다. 이러한 결과는 본 논문에서 제안하는 패킷 전송 지연에 따른 전력량 이득 추산 모델과 이를 활용한 선별적 패킷 전송 지연 기법이 최신 모바일 장치에 탑재된 모뎀의 전력 소모량을 줄이는 실용적이고 효과적인 수단임을 보여준다.1. 서론 1 1.1 연구 동기 3 1.2 연구 내용 5 1.3 논문 구성 9 2. 배경 지식과 관련 연구 10 2.1 무선 자원 제어 프로토콜과 비연속적 수신 기법 10 2.2 모뎀의 전력 소모량 절감 기법 19 2.1.1 Tail 시간의 빠른 종료 24 2.2.2 Tail 시간들의 중첩 28 3. 문제 설명과 해결 방안 개관 33 3.1 시스템 모델 33 3.2 문제 설명 39 3.3 해결 방안 개관 45 4. 선별적 패킷 전송 지연 기법 50 4.1 지연 가능 패킷의 판별 50 4.2 모바일 장치의 다음 패킷 전송 요청 시점 예측 53 4.2.1 패킷 전송 요청 그룹의 생성 53 4.2.2 패턴 검출 57 4.2.3 다음 패킷 전송 요청 시점의 예측 63 4.3 예상 전력 이득에 기반한 패킷 전송 시점의 결정 66 5. 구현과 실험적 평가 78 5.1 선별적 패킷 전송 지연 기법의 구현 78 5.2 실험 설정 89 5.3 실험 결과 92 5.4 분석적 평가 99 6. 결론 104 참고 문헌 107 Abstract 115Docto

A Task Offloading Framework for Energy Saving on Mobile Devices using Cloud Computing

Over the last decade, mobile devices have become popular among people, and their number is ever growing because of the computing functionality they offer beyond primary voice communication. However, mobile devices are unable to accommodate most of the computing demand as long as they suffer the limited energy supply caused by the capacity of their small battery to store only a relatively small amount of energy. The literature describes several specialist techniques proposed in academia and industry that save the mobile device energy and solve this problem to some extent but not satisfactorily. Task offloading from mobile devices to cloud computing is a promising technique for tackling the problem especially with the emergence of high-speed wireless networks and the ubiquitous resources from the cloud computing. Since task offloading is in its nascent age, it lacks evaluation and development in-depth studies. In this dissertation, we proposed an offloading framework to make task offloading possible to save energy for mobile devices. We achieved a great deal of progress toward developing a realistic offloading framework. First, we examined the feasibility of exploiting the offloading technique to save mobile device energy using the cloud as the place to execute the task instead of executing it on the mobile device. Our evaluation study reveals that the offloading does not always save energy; in cases where the energy for the computation is less than the energy for communication no energy is saved. Therefore, the need for the offloading decision is vital to make the offloading beneficial. Second, we developed mathematical models for the energy consumption of a mobile device and its applications. These models were then used to develop mathematical models that estimate the energy consumption on the networking and the computing activities at the application level. We modelled the energy consumption of the networking activity for the Transmission Control Protocol (TCP) over Wireless Local Area Network (WLAN), the Third Generation (3G), and the Fourth Generation (4G) of mobile telecommunication networks. Furthermore, we modelled the energy consumption of the computing activity for the mobile multi-core Central Processing Unit (CPU) and storage unit. Third, we identified and classified the system parameters affecting the offloading decision and built our offloading framework based on them. In addition, we implemented and validated the proposed framework experimentally using a real mobile device, cloud, and application. The experimental results reveal that task offloading is beneficial for mobile devices given that in some cases it saves more than 70% of the energy required to execute a task. Additionally, our energy models accurately estimate the energy consumption for the networking and computing activities. This accuracy allows the offloading framework to make the correct decision as to whether or not offloading a given task saves energy. Our framework is built to be applicable to modern mobile devices and expandable by considering all system parameters that have impact on the offloading decision. In fact, the experimental validation proves that our framework is practical to real life scenarios. This framework gives researchers in the field useful tools to design energy efficient offloading systems for the coming years when the offloading will be common.4 month

Methodologies for Evaluating User Centric Performance of Mobile Network Applications

Performance is an important attribute of mobile software applications, having a direct impact on end-user's experience. One of the obstacles that make software performance testing difficult to pursue is the lack of performance requirements that complicates the process of verifying the correctness of the test case output. Moreover, compared to other platforms, mobile applications' quality assurance is more challenging, since their functionality is affected by the surrounding environment. In this work, we propose methodologies and frameworks to evaluate the impact of interaction of the quality of the wireless network connection and application configurations on performance behaviour and performance robustness of a mobile networked application as perceived by the end user. We follow a model-based approach. The thesis starts by defining the system model of software applications that we target, the network stack that the application is assumed to use to provide the service to the end user, and the metric used to capture the quality of the provided network service. Then, an analytical performance model that captures the application-network interactions is developed using the Markovian framework. To model realistic interactions with the network, the performance model is developed and solved using supplementary variable technique (SVT). The model is intensively verified with simulation. Furthermore, two input network models are analytically developed. In both models, the mobile application is assumed to have a wireless network access through a WiFi access point that implements IEEE 802.11 protocol. In the first model, data transfer is achieved using user datagram protocol (UDP), while in the second, data transfer is accomplished using transmission control protocol (TCP). For the TCP model, two scenarios are considered. In the first scenario, an application data unit (APDU) is assumed to fit in one TCP packet, while in the second scenario, an APDU is assumed to fit in multiple TCP packets. All models are verified using the well-known NS2 network simulator. Third, we propose a model based test generation methodology to evaluate the impact of the interaction of the environment, the wireless network, and the application configurations on the performance of a mobile networked application. The methodology requires four artefacts as inputs, namely, a behaviour model of the software under test, a network model, a test coverage criterion, and a set of desired performance levels. The methodology consists of three steps: performance model development, test generation, and estimation of test execution parameters. To evaluate the end-user quality of experience, test generation is formulated as an inversion problem and solved as an optimization problem. To generate an efficient set of test cases, two test coverage criteria are proposed: user experience (UE) and user experience and input interaction (UEII). Test execution optimizations are inferred using a performance simulation model. To show the applicability of the methodology, two mobile networked app examples are used: multimedia streaming and web browsing. The effectiveness of the methodology is evaluated by comparing the time cost to design a test suite with random testing. The obtained results are very promising. Fourth, to minimize the incurred cost of performance model evaluations, we utilize metamorphic testing to generate test cases. Metamorphic testing is a technique that is proposed to alleviate the test oracle problem. By utilizing certain inherent properties of the system under test (metamorphic relations), test cases are generated and verified without the need to know the expected output of each individual test case in advance. By hybridizing our proposed test generation methodology with metamorphic testing, the time cost of generating a test suite is reduced tremendously. We first generate a limited set of seed test cases using our test generation methodology. Then, we generate a set of follow-up test cases by utilizing the developed network models as metamorphic relations and without the need to invoke the performance model. Follow-up test generation is formulated as a maximization problem. The objective is to maximize the distance between a seed test case and follow-up test cases so that to generate a non-redundant set of test cases. Three distance metrics are used: Euclidean, squared Euclidean, and Manhattan. The modified methodology is used to generate test cases for a multimedia streaming application. We empirically evaluate the modified test generation methodology using two evaluation metrics: the incurred time cost and the percentage of redundancy in the generated test suite. The obtained results show the advantage of the modified methodology in minimizing the cost of test generation process. Fifth, we propose a third methodology to evaluate the impact of the wireless network conditions on robustness of performance of adaptive and non-adaptive mobile networked applications. Software robustness is mainly about how the system behaves under stressful conditions. In this work, we target performance robustness under stressful network conditions. The proposed methodology consists of three steps and it requires three different artefacts as inputs. To quantify robustness, two metrics (static and dynamic robustness) are proposed. The main challenge in evaluating robustness is the combinatorial growth of network-application interactions that need to be evaluated. To mitigate this issue, we propose an algorithm to limit the number of interactions, utilizing the monotonicity property of the performance model. To evaluate the dynamic robustness metric, the ability of the adaptive application to tolerate degraded network conditions has to be evaluated. This problem is formulated as a minimization problem. The methodology is used to evaluate the performance robustness of a mobile multimedia streaming application. The effectiveness of the proposed methodology is evaluated. The obtained results show three to five times reduction in total cost compared to the naive approach in which all combinations are exhaustively evaluated