Android Operating System

Smartphone devices such as iPhone, Blackberry, and those that support the Android operating system are progressively making an impact on society. In addition to their support for voice and text exchange, smartphones are capable of executing sophisticated embedded software applications, as well as provide a simple link to the Internet and its resources.

Android is a software stack for mobile devices that includes an operating system, middleware and key applications. Android's mobile operating system is based on a modified version of the Linux kernel. The increasing interest from the industry arises from two core aspects: its opensource

nature and its architectural model. Being an open-source project, allows Android to be fully analysed and understood, which enables feature comprehension, bug fixing, further

improvements regarding new functionalities and, finally, porting to new hardware. On the other hand, its Linux kernel-based architecture model also adds the use of Linux to the mobile industry, allowing taking advantage of the knowledge and features offered by Linux. Both of these aspects make Android an appealing target to be used in other type of environments. Another aspect that is important to consider when using Android is its own Virtual Machine (VM) environment. Android applications are Java-based and this factor entails the use of a VM environment, with both its advantages and known problems. In computing, a solution stack is a set of software subsystems or components needed to deliver a fully functional solution, e.g. a product or service. Middleware is computer software that connects software components or some people and their applications. Software that provides a link between separate software applications. Middleware is sometimes called plumbing because it connects two applications and passes data between them. Middleware allows data contained in one database to be accessed through another. The Android opensource software stack consists of Java applications running on a Java-based, object oriented application framework on top of Java core libraries running on a Dalvik virtual machine featuring JIT compilation. Libraries written in C include the surface manager, Open Core media framework, SQLite relational database management system, OpenGL ES 2.0 3D graphics API, WebKit layout engine, SGL graphics engine, SSL, and Bionic libc.. The Android operating system, including the Linux kernel, consists of roughly 12 million lines of code including 3 million lines of XML, 2.8 million lines of C, 2.1 million lines of Java, and 1.75 million lines of C++. Android uses WAVE & CALFIT. WAVE is an API for Android OS which allows easy management of by sensor networks (BSNs) on mobile platforms. It present a simple framework for health-oriented applications by providing functionality for data collection from sensors and data processing.

The platform is adaptable to larger, VGA 2D graphics library, 3D graphics library based on OpenGL ES 2.0 specifications, and traditional smartphone layouts.

Android supports connectivity technologies including GSM/EDGE, IDEN, CDMA, EV-DO, UMTS, Bluetooth, Wi-Fi, LTE, NFC and WiMAX.

Android supports the following audio/video/still media formats: WebM, H.263, H.264 (in 3GP or MP4 container), MPEG-4 SP, AMR, AMR-WB (in 3GP container), AAC, HE-AAC (in MP4 or 3GP container), MP3, MIDI, Ogg Vorbis, FLAC, WAV, JPEG, PNG, GIF, BMP, WebP.

SMS and MMS are available forms of messaging, including threaded text messaging and Android Cloud To Device Messaging (C2DM) and now enhanced version of C2DM, Android Google Cloud Messaging (GCM) is also a part of Android Push Messaging service.

Android supports multiple languages.

RTP/RTSP streaming (3GPP PSS, ISMA), HTML progressive download (HTML5

Android can use video/still cameras, touchscreens, GPS, accelerometers, gyroscopes, barometers, magnetometers, dedicated gaming controls, proximity and pressure sensors, thermometers, accelerated 2D bit blits (with hardware orientation, scaling, pixel format conversion) and accelerated 3D graphics.

Android has native support for multi-touch which was initially made available in handsets such as the HTC Hero. The feature was originally disabled at the kernel level (possibly to avoid infringing Apple's patents on touch-screen technology at the time). Google has since released an update for the Nexus One and the Motorola Droid which enables multi-touch natively.

Supports A2DP, AVRCP, sending files (OPP), accessing the phone book (PBAP), voice dialing and sending contacts between phones. Keyboard, mouse and joystick (HID) support is available in Android 3.1+, and in earlier versions through manufacturer customizations and third-party applications.

Android does not support native video calling, but some handsets have a customized version of the operating system that supports it, either via the UMTS network (like the Samsung Galaxy S) or over IP. Video calling through Google Talk is available in Android 2.3.4 and later. Gingerbread allows Nexus S to place Internet calls with a SIP account. This allows for enhanced VoIP dialing to other SIP accounts and even phone numbers. Skype 2.1 offers video calling in Android 2.3, including front camera support.

Multitasking of applications, with unique handling of memory allocation, is available.

Google search through voice has been available since initial release. Voice actions for calling, texting, navigation, etc. are supported on Android 2.2 onwards.

Android supports tethering, which allows a phone to be used as a wireless/wired Wi-Fi hotspot. Before Android 2.2 this was supported by third-party applications or manufacturer customizations.

Android supports capturing a screenshot by pressing the power and volume-down buttons at the same time. Prior to Android 4.0, the only methods of capturing a screenshot were through manufacturer and third-party customizations or otherwise by using a PC connection (DDMS developer's tool). These alternative methods are still available with the latest Android.

Most Android devices include microSD slot and can read microSD cards formatted with FAT32, Ext3 or Ext4 file system. To allow use of high-capacity storage media such as USB flash drives and USB HDDs, many Android tablets also include USB 'A' receptacle. Storage formatted with FAT32 is handled by Linux Kernel VFAT driver, while 3rd party solutions are required to handle other popular file systems such as NTFS, HFS Plus and exFAT

The following diagram shows the major components of the Android operating system.

Each section is described in more detail below. It consist of four layers: Application,

Application framework, the layer below is divided in two parts: libraries and Android

RunTime, and the last layer is Linux Kernel.

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4. ADVANTAGES

• 
  Wide range of mobile application.
  
• 
  one will be able to customize a mobile phones using Google Android platform , right down to the screen. Features like weather details, opening screen, live RSS feeds and even the icons on the opening screen will be able to be customized.
  

• 
  In addition, as a result of many mobile phones carrying Google Android, companies will come up with such innovative products.
  

• 
  In addition the entertainment functionalities will be taken a notch higher by Google Android being able to offer online real time multiplayer games.
  

Some of disadvantages of Android Operating System are:

• 
  Rejection of Google Android by carriers who charge a fee for some of the web based applications which Google Android will enable mobile phone holders to access free of charge.
  
• 
  Since Google Android is an open source platform driving all Android phones, it could significantly increase the risk of hacking these devices.
  

Now cell phone is the major part of everyone‘s life. Android making them more and more users

interactive by providing lots of applications and services. Its large touch pad and sensor mode

provide easy access to user. As all the mobile applications are build in java but android does not

have any java virtual machine, there is a special virtual machine which is built for Android that is

Dalvik virtual machine which compiles the code in .dev form. Android support for real time

application, providing four different directions making it a real time system.

6. REFERENCES

[1] ―About the Android open source project‖http://source.android.com/about/index.html.

[2] Android Developers. 21 July 2009. http://developer.android.com/guide/basics/what-isandroid.

html.

the original on 2011-02-23. http://www.webcitation.org/5wiw1JXa2.

[4] http://en.wikipedia.org/wiki/Android_(operating_system)

[5] http://www.lextrait.com/Vincent/implementations.html

[6] http://www.seeingwithsound.com/android.html

[7] Medical application for Android powered mobile systems by Gray S. Tyson and Ford

Tyson in CSI communication 8 April 2011. Journal of the American Geriatrics Society,

Vol. 58,No. 3, April 2010.

[8] Open Handset Alliance, ― Android overview,‖ http://www.openhandsetalliance.com/

[9] android_overview.html.

[10] Research paper on ―Evaluating Android OS for Embedded Real-Time Systems‖.

CISTER Research Centre, School of Engineering of the Polytechnic Institute of Porto in

Euromicro Conference on Real- time systems (ECRTS- 2010) july 6, 2010.

[11] Technical trands – smart phones, smart people by Harikumar P Travancore