Efficient Energy Consumption Approach during Browsing in Android Smartphones

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International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459,ISO 9001:2008 Certified Journal, Volume 5, Issue 5, May 2015)

180

Efficient Energy Consumption Approach during Browsing in

Android Smartphones

Ashwini M. Sonwane

Department of Computer Science & Engineering, Deogiri Institute of Engineering & Management Studies, Dr. B.A.M.U., Aurangabad, India

Abstract—Due to some additional characteristics of the wireless radio interface, web browsing via smart phones requires a lot of power while downloading webpages. Proposed system identifies special characteristics, and address power consumption issues through two novel techniques. We proposed a framework for measuring the specified energy used by a mobile browser to deliver web pages to users. Proposed method adequately specifies a tool to analyze the energy required for delivery of particular web elements, such as cascade style sheets (CSS), images, Javascript. With the help of gathered information we conclude some endorsement on designing of web pages to curtail the energy required to deliver the page. Furthermore, proposed method can further decrease the webpage loading time and increase the network capacity.

Keywords- Energy Consumption, Mobile Computing, Portable devices, Wireless Communication, Web Browser

I. INTRODUCTION

Smartphones are well known for their rapid support for web browsing. Still, the current smartphone wastes tremendous amount of power during downloading web pages. There have been lots of research to optimize the power usage of smartphone, but they focus on display to curtail power consumption. Other focus is on WiFi interface which has different characteristics than cellular interfaces such as 3G and 4G LTE, which also absorbs huge amount of power [1]. UMT S 3G and 4G LTE networks used multiple timers to command the resource and the timeout value to commute the resources. So, there is possibility that wireless radio interface absorbs huge amount of power before timer exits, even when there is no network traffic. Advantage of this technique is that it can curtail the latency of next possible data transmission that reaches before the timer quits, because the connection between the smartphone and the determined network is still available. Otherwise, the determined network has to allot the resource again, which will absorbs more time and power. As a result, naturally adjusting the timer may not be a good solution for saving power.

Due to the finite calculation of capability, during opening of a webpage, current smartphone web browser takes a lengthy time period for downloading and processing all objects of the webpage.

As a result, the data transmissions are assigned along the whole webpage downloading duration, and then the data rate at any instant time is quite low. Although there are many useless times between these data transmissions, each useless time period is still smaller than the time out value, and these data transmissions reboot the timers repeatedly before they lapse. Therefore, the radio interface is always on and the radio resource cannot be discharged, which absorbs huge power and shrinks the network capacity [2].

Proposed system direct the two novel approaches for solving problems in power utilization during web browsing. Firstly, we reconstruct the computation sequence of the web browser when processing a webpage. There are various calculations when processing a webpage such as HTML parsing, JavaScript code execution, image decoding, style formatting, page layout, etc. These calculations belongs to two streams based on generation of new data transmissions from web server. We want to isolate these two types of calculations so that the web browser can first run the calculations that will responsible for generation of new data transmissions and retrieve these data from server. Then, the web browser can put the wireless radio interface into low power state, discharge all the radio resource, and then run the remaining calculations which may take 40 –70% of the processing time for processing webpages [3]. Thus, a significant amount of power and radio resource can be saved.

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International Journal of Emerging Technology and Advanced Engineering

181 II. RELATED WORK

There have been many research for advancing the power management of smart phones, but they focus on display of smartphones to curtail power consumption. Some of them focus is on wireless interfaces such as WiFi or Bluetooth interface to reduce the power consumption [1].

As users of 3G smartphones are increasing day by day, power consumption of the 3G wireless interface problem becoming severe issue. Zhao et al. [1] proposed an architecture called virtual-machine based Proxy (VMP), which shifts the computation from smartphones to VMPs to save power and delay for web browsing in 3G networks. Bartendr [4] founds the relationship between signal strength and power consumption, and lineups the communication based on the signal strength to recover power. Analytical models are used to measure power consumption of mobile devices with different timer values. They focus on the changing timer values to save power. Different from previously executed work, our technique updates the timer based on the predicted reading time Complementary to this work, Qian et al. [5] proposed caching techniques to reduce the power consumption and improve the radio resource utilization for web browsing in 3G networks.

To enhance transmission delay, grouping of multiple transmissions are done by holding them. Many latest smartphones and networks support the fast dormancy feature supported by 3GPP [6]. Using this approach, smartphone can contact to the network to notify the completion of data transmission, and thus the smartphone can settle to low power level. Fast dormancy may waste power on switching the smartphone back to high power level. Speculative parsing and Google SPDY controls the webpage loading time. Speculative parsing is finite due to dependency requirements in the DOM tree. This is different from our approach which parses the whole file to fetch all objects related to data transmission so that the wireless interface can enter sleep earlier [9].

1) Power Consumption of the 3G Radio Interface:

To efficiently utilize the limited radio resource of the backbone network [10], the 3G Radio Resource Control protocol defines the following three states for smart phones to control their radio interface as follow/s:

 IDEL State: This State Slightly consumes Power. Smart Phone can’t send user data due to non-signaling connections with backbone network.

 DCH State: In this state, Smartphone can send user data because dedicated transmission channels to the Smartphone, it require more power.

[image:2.612.346.520.176.287.2]

 FACH State: Compare to IDEL and DCH State it require low speed to transmit user data and signaling data through common shared transmission channels [11].

Fig. 1: The power level of the 3G radio interface on smartphones at different states.

2) Web Browser Design:

Web browser is multipart design which use various scripting language and design such as Html, DHTMl, XML, JavaScript, and CSS Style Sheet. These are used with HTML Language. CSS used for Particular template design. Document Object Model (DOM) is edge that allows program and scripting to inform Code, structure and style of document. Dom parses the code of html and CSS then DOM tree node store html data and CSS style and layout properties assign. After that we can see web page on screen [2].

When web browser receives the main HTML page, data transmission takes place due to three types of sources: HTML, CSS and JavaScript. Objects such as HTML files, JavaScript files, images and flashes, of HTML and CSS, are mentioned by URLs. Web browser required to fetch and attached them to the DOM tree as a node. JavaScript is either converted to HTML code and then retrieves objects or it can directly obtain content objects from the web server.

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International Journal of Emerging Technology and Advanced Engineering

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182

Fig. 2: The workflow of webpage processing in smartphone based web browser

As shown in Fig. 2, in the latest smartphone web browser, there are two types of calculations combined with each incoming object. The first type is the calculations that achieves new data transmissions such as HTML and CSS file parsing and JavaScript code execution, which are commonly known as the data transmission computation. The second type is the computation that does not cause data transmission. This type of computation is used to lay out the webpage such as image decoding, style formatting, page layout calculation and page rendering, which is referred to as the layout computation.

Images, Javascript, and CSS are the power eager web components of a web page. We have to enhance web pages so as to curtail the power consumption of these elements.

1) Reducing Javascript Power Consumption

Javascript is the most energy absorbing components of a web page. Websites using Javascript requires a huge download and energy. This happens because of these webpages load large Javascript files for delivering the web pages to users even though there is no need of all script for loading web page.

The Wikipedia webpage attached with two Javascript as application.js and jquery.js. The application.js Javascript is precise to the Wikipedia site and the jquery.js Javascript is precise to the generic jquery Javascript library. Each section of Wikipedia page such as introduction, history, Table of Contents, etc. can be crash and developed by the click of a button above each section of a page.

The jquery.js Javascript is mainly needed to dynamically describe the correct section depending on the id of the button clicked. But loading of this single Javascript in to the memory requires 4 Joules of energy.

Reducing Javascript on a mobile page to include only those functions required by the page highly decrease energy use. Generic Javascript libraries simplifies web development, but highly increases the energy used by the resulting pages [2].

2) Reducing CSS Power Consumption

Huge CSS files with unwanted CSS rules absorbs more energy than minimum needed energy. Apple absorbs a large amount of energy to download and deliver CSS. It requires 12 Joules of energy for downloading and delivering purpose. Reason behind this is that Apple homepage uses 5 different CSS files containing distinct rules used in the page.

The logic to avoid energy consumption is to replace multiple CSS files by single file which consists of all rules required for the webpage. This idea conclude energy drop up to 5 Joules. This energy consumption can be saved by using single CSS file with only the required CSS rules. CSS file should be page precise and must include only those rules which are useful to elements in the page [2].

3) Image Formats: Comparison and Optimization

Most commonly, web sites uses various types of image

formats, as JPEG, GIF, and PNG. But the energy

consumption to deliver an image to user totally depends on the setting of encoding format. We can easily compare the energy consumptions of the different types of image format. Let us consider 3 dominant image formats as PNG, JPEG and GIF. GIF format supports 8-bits per pixel and uses the Lempel-Ziv-Welch (LZW) lossless data compression method. PNG is uses a bitmapped image format that was invented to boost upon and replace GIF. PNG also supports for lossless data compression. JPEG is another prominent image format that supporting lossy data compression. In mobile web browsing, mostly, GIFs are used for very small size images, and PNGs and JPEGs are

used for larger images. JPEG is the more energy efficient

format on the Android mobile phone for all image sizes [2].

III. PROPOSED SYSTEM

A. Proposed Architecture:

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International Journal of Emerging Technology and Advanced Engineering

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Fig 3: System architecture

Proposed method provides analysis of the energy re-quired to deliver famous web sites and the energy rere-quired to deliver particular web elements such as images, cript, and Cascade Style Sheets (CSS). Complicated Javas-cript and CSS can be costly to deliver as images in web pages. Furthermore, request for dynamic Javascript by user can extremely boost the cost of delivering the page because it avoids caching of contents of web page. Delivery of JPEG images is appreciably less expensive than other for-mats such as GIF and PNG for comparable size images on the Android browser. For example, try to translate all imag-es on the Facebook web site to JPEG and check the rimag-esult to obtain considerable energy savings. Our conversion easily changes working of Javascript on the page, without altering the user experience. We just have to modify the default Android browser. Our modified browser instru-ments fully load a URL P in one of two modes.For that we define two approaches as below:

• No Cache:

Before starting to load the URL, browser cache is made clear. Result of this is all elements of web page are get downloaded first from network and then delivered on the phone. This approach analyze the total energy used for navigating to the page, including 3G transmission, parsing HTML, and delivering

• With Cache:

There is no need to use the radio to download any content of web page as all elements of the web page are previously present in the browser cache. This approach analyze the energy required to parse and deliver HTML from cache. No 3G traffic is granted in this approach.

Proposed method includes two components: (1) a Browser Profiler, an Android application we wrote, and (2) the built-in Android Browser with some changes. We have refer to these components as Profiler and Browser respectively. Our proposed technique and methodology mathematics is as follows:

B. Measurement Workflow:

The profiler introduces an easy user interface that takes input as URL P and number of iterations n. When user press a button to start with profiling, its profiler’s duty to take care that web page P get loaded in NO CACHE mode. For that, Profiler firstly direct the browser to empty its cache by performing ACTION_CLEAR CACHE intent. In response, browser clears its cache and sends back CACHE_CLEARED intent to Profiler. When the process of page loading is completed, user taps the BACK button to switch the control back to Profiler. This process is repeated n times and represents n page loads of P in NO_CACHE mode. When NO_CACHE mode is finishes its execution, all components of page P will be present in the browser cache.

At last, profiler directs to load web page P again n times with the help of sequence of ACTION_VIEW intent and BACK button as before. However, we do not clear the cache after every load this time. So, this represents n page loads of P in WITH_CACHE mode.

C. Offloading via a Front-end Proxy:

There are two types of offloading calculations as Front end proxy and Back-end server.

Front-end proxy:

A web proxy checks entire traffic to the phone and fractionally deliver the page to save work for the phone. Proxy used here conclude the modifications in the contents before it gets deliver to the phone. WAP gateways used this technique to convert HTML to WAP. This technique is also used by Opera and SkyFire, but is not used by the default Android or iPhone browsers.

Back-end server:

The phone downloads web content as it is, but then offloads certain operations to a server claim. Here the phone itself decides what needs to be offloaded.

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International Journal of Emerging Technology and Advanced Engineering

184 The energy savings that result from a front-end proxy that down-scales all large JPEG images to 160 pixel width. Since all images larger than 160x160 are scaled down by the proxy, the energy beyond that image size is flat.

D. Down-scaling is not without limitations:

• By down-scaling images, users lose the ability to quickly zoom in on intricate image details. Instead, a zoom-in requires downloading the zoomed part of the image. But the more common case is that no zooming takes place.

• For content sent encrypted using SSL, the proxy cannot see the content and therefore cannot down-scale it. Down-scaling can be offered as an option to users to improve the browsing experience on the phone.

To calculate energy consumed by any element of a web page, we must have to copy that web page on our servers, then we can easily compare the energy consumption used for loading and delivering the full page to the energy consumption needed for loading and delivering the page after deletion of particular components of a web page. Difference between two entries provides evaluation of the energy required to present the component. First we estimate the total energy used for loading and delivering each component of a web page, which includes both delivering and transmission energy. Based on this, we estimate parsing and delivering energy separately, by forcing the browser to cache all content locally on the phone.

Mathematical Model

To compute energy model for protected web browsing on mobile device, we firstly find out the components which are responsible for heavy energy consumption at the time of web browsing session. These process required energy to be drained out at the TLS handshaking phase along with and the secure Web data exchange phase. We partition en-ergy absorbing components into two parts as enen-ergy drained from the battery as a result of communications ac-tivities (data transmission and reception) and energy drained from the battery as a result of processing activities (data encryption, decryption, hashing, etc.).

ETotal + EHandshake = EWeb (1)

Above equation (1) shows the total energy consumption in mobile device. EHandshake stands for energy consumption

at the TLS handshaking phase and EWeb stands for energy

consumption at the HTTP application-layer data exchange phase.

EHandshake + EH-Exchange = EH-Proc (2)

Above equation (2) shows the energy consumption in handshaking step, where EH-Exchange takes energy exhausted

during communications activities at the time of handshak-ing phase.

EH.Exchange=

Er.(BCilentHello+BClientKeyExchange+BChangeCipherSpec+BFinished)+ER(

B

Server

Hel-lo+BClientKeyExchange+BServerDone+BChangeCipherSpec+BFinished)+E1.(T

Handshake+Er.NHExchange.BTCPIP+ER.NH-ExchangeBTCPIP)+ETCP.H

• ET stands for energy absorption per byte at time of data transmission, ET stands for energy absorption per byte at time of data reception, EI stands for energy absorption per byte at time of idle mode.

• BH1 is the total size of the ClientHello message in bytes.

BH2 is the total size of the ClientKeyExchange, client

ChangeCipherSpec, and client Finished messages. BH3 is

the total size of the ServerHello, ServerKeyExchange, and ServerHelloDone messages. BH4 is the total size of

the server ChangeCipherSpec and server Finished mes-sages because they are normally sent together.

• ƬHandshake is the total time of the handshaking phase.

Mul-tiplication of t Handshake by EI results into total ideal energy absorption while performing handshaking phase • NH-Exchange, T denotes the total number of handshaking

protocol packets transformation from the mobile device while performing the handshaking phase. Generally it acquires value as 2 because BH1 and BH2 are smaller than

the maximum transfer unit (MTU) size and thus require one link layer frame for each MTU. NH-Exchange, T is the total number of handshaking protocol packets re-ceived by the mobile device.

• BTCP/IP stands for size of header included into transport

(TCP), network (IP), and data link (Ethernet) layers. ETCP-H is denotes energy absorption at the time of TCP

operation while performing handshaking procedure which consists of transmission and reception of TCP segments as part of the TCP connection setup phase. EH-Proc takes the energy absorbed emerged from

pro-cessing activities in the mobile device with help of the TLS handshaking procedure. It can be modeled as follows:

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International Journal of Emerging Technology and Advanced Engineering

185 Where EKeyGen denotes the total energy absorbed during

key generation-processing activities along with pre-master secret encryption by using RSA, ECertVerify stands for the

energy consumed at the time of processing activities to check the server certificate, EFinished is the energy deplete at

the end of message hashing.

Generally, we have carry out handshaking process repet-itively for each object in the website either in full mode or in an abbreviated mode to restart a TLS session. In restart-ed session of TLS only hello, change cipher spec, and fin-ished messages are transferred which results into bypass for execution of key generation and RSA algorithm.

IV. CONCLUSIONS

We proposed an experimental infrastructure for calculating the power consumption of web pages, consisting precise component on the page. Proposed technique provides different view for evaluating web sites. It also provides new version to web developers for constructing more energy economical sites. We proposed an energy-aware technique for web browsing in 3G based smartphones. First, we rearrange the computation sequence for loading webpage. So that web browser first of all will run the webpages having calculations that will produce new data transmissions and fetch these data from browser. The web browser then put the 3G radio interface into IDLE state, discharge the radio resource, and then run the remaining layout computation. This technique not only saves power as well as time period for processing webpage. Secondly, we can predict the reading time of webpage after it gets downloaded. If the predicted reading time is larger than a threshold, proposed technique is used. Additionally, our approach can also increase the network capacity, since the radio resource can be released earlier.

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