tag:blogger.com,1999:blog-46288832435110252612024-03-13T09:01:08.090+05:30Tech-A-Break !!Tech-Knowledgy Nuggets of Android, GCC, Compiler and much morepriyankahttp://www.blogger.com/profile/13978896481000985823noreply@blogger.comBlogger9125tag:blogger.com,1999:blog-4628883243511025261.post-3059058301443775782014-02-19T16:35:00.001+05:302014-02-24T18:58:47.980+05:30Fundamental blocks of an Android Application<div dir="ltr" style="text-align: left;" trbidi="on">
This article will provide an overview of the android application components from a developer's point of view.<br />
<br />
In order to develop an Android application, we need to first know what components make up an android app. There are four fundamental components which form an Android App. These building blocks, which are implemented as JAVA classes, are:<br />
<br />
<ul style="text-align: left;">
<li>Activity Class - Activities provide the GUI to the user of the application, enabling the user to enter and receive data. Therefore, we can say this component works in the foreground, i.e, is visible to the user.</li>
</ul>
<ul style="text-align: left;">
<li>Service Class - Services allow the different processes to request operations and share data.</li>
</ul>
<ul style="text-align: left;">
<li>Broadcast receiver - This block can be considered like a dormant component, waiting for an event to occur, like a message to be received, or battery level going below 5% etc. and take actions like show notifications.<br /><br /><div class="separator" style="clear: both; text-align: center;">
<a href="http://3.bp.blogspot.com/-uMbRZYJ2WSw/UwSOm0F5qOI/AAAAAAAAG-Q/KvS7ZhlKen4/s1600/not.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em; text-align: center;"><img alt="broadcast receiver notification" border="0" src="http://3.bp.blogspot.com/-uMbRZYJ2WSw/UwSOm0F5qOI/AAAAAAAAG-Q/KvS7ZhlKen4/s1600/not.jpg" title="Notification of broadcast receiver" /></a></div>
<div style="text-align: left;">
<br />
Consider, the watchman of your Apartment. He sits at the main gate of the complex, dormant. While you are inside your flat unaware of any activity occurring outside. Now say, some friend decides to visit you. This friend reaches the complex gates. The watchman sitting there, stops the visitor, finds out which flat this visitor wants to go to, and then notifies you through intercom that - You have a visitor! In this case the watchman acts like the Broadcast receiver of an Android application.</div>
</li>
</ul>
<div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<ul style="text-align: left;">
<li>Content Provider - We have discussed the Content Provider before <a href="http://wirelessthought.blogspot.in/2014/01/the-android-application-framework.html" target="_blank">(read here)</a>. Content Provider enables data sharing between Android applications. It allows data to be centralised at one place like a database, however, it has many more other functions than being just a database.</li>
</ul>
Now that we have some idea of the organisation of our application, next we will delve into details in the next post.<br />
<br />
<div>
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<span style="color: #990000; font-family: inherit; font-size: x-small;">Hope this Android Application Development tutorial is helping. If not, please lets us know.</span></div>
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priyankahttp://www.blogger.com/profile/13978896481000985823noreply@blogger.com0tag:blogger.com,1999:blog-4628883243511025261.post-55734377314577263982014-02-07T19:29:00.000+05:302014-02-19T16:47:46.036+05:30LEARN ANDROID FOR FREE<div dir="ltr" style="text-align: left;" trbidi="on">
<div class="separator" style="clear: both; text-align: center;">
<a href="http://3.bp.blogspot.com/-mSP7D4Alj5c/UvTmTNX1LRI/AAAAAAAAG90/uJ3lQu98CXk/s1600/graphic-card-for-android-improve-performance-of-android-phone1.jpeg" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="Learning Android Easy" border="0" src="http://3.bp.blogspot.com/-mSP7D4Alj5c/UvTmTNX1LRI/AAAAAAAAG90/uJ3lQu98CXk/s1600/graphic-card-for-android-improve-performance-of-android-phone1.jpeg" height="360" title="Learn Android for free" width="640" /></a></div>
<h4 style="text-align: left;">
Want to have your own android app some day?</h4>
A lot of us want to learn writing Android Apps. But where does one start?<br />
<br />
It looks like a daunting and never ending task. There are a million resources to learn from, but when you look at the never-ending list of documentation they have, it seems like you are drowning in a sea of information and yet starving for a drop of practical knowledge. Following this, many have given up there quest for Learning Android.<br />
<br />
<table cellpadding="0" cellspacing="0" class="tr-caption-container" style="float: right; margin-left: 1em; text-align: right;"><tbody>
<tr><td style="text-align: center;"><a href="http://farm3.staticflickr.com/2759/5708487972_0cb873229e_z.jpg" imageanchor="1" style="clear: right; margin-bottom: 1em; margin-left: auto; margin-right: auto;"><img alt="Android learning easy and free" border="0" src="http://farm3.staticflickr.com/2759/5708487972_0cb873229e_z.jpg" height="320" title="Google's Android" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Add caption</td></tr>
</tbody></table>
However, the truth is you don't have to read tons and tons of documentation of Android Manual and resources to learn Android. You can learn Android for free and within a short time.<br />
<br />
Don't get confused. Start learning for free.<br />
<br />
If you are looking for a guide to learning Android the practical way, you have found the right place. My posts have the gist of all the documentation. And you need nothing except a laptop/PC and this blog will set you rolling.<br />
<h4 style="text-align: left;">
How to use this blog to learn Android App Development free</h4>
<div>
Book mark this page . Start here and follow this list in order. I will keep updating as and when needed.</div>
<div>
<ol style="text-align: left;">
<li><span style="text-decoration: none;"><a href="http://wirelessthought.blogspot.in/2014/02/develop-android-app.html" style="text-decoration: none;">How to develop a mobile application using Android</a></span></li>
<li><span style="text-decoration: none;"><a href="http://wirelessthought.blogspot.com/android-basics.html" style="text-decoration: none;">Basics of Android</a></span></li>
<li><span style="text-decoration: none;"><a href="http://wirelessthought.blogspot.in/2014/01/the-android-application-framework.html" style="text-decoration: none;">The Android Application Framework</a></span></li>
<li><h3 class="post-title entry-title" itemprop="name" style="background-color: white; margin: 0px; position: relative;">
<span style="font-family: inherit; font-size: small; font-weight: normal;"><a href="http://wirelessthought.blogspot.in/2014/02/fundamental-blocks-of-android.html" target="_blank">Fundamental Blocks of an Android Application</a></span></h3>
</li>
<li>to be continued..</li>
</ol>
</div>
<br />
<br />
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<span style="color: #990000; font-family: inherit;">Do you have Questions? Arguments? doubts?... we'll try our best to resolve</span></div>
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priyankahttp://www.blogger.com/profile/13978896481000985823noreply@blogger.com0tag:blogger.com,1999:blog-4628883243511025261.post-21819890306309983002014-02-04T13:14:00.002+05:302014-02-07T17:49:49.072+05:30How to develop a mobile application using Android<div dir="ltr" style="text-align: left;" trbidi="on">
So, You want to develop your own mobile application that would run on Android. You are at the right page. This and a lot more posts will teach beginners how to develop an android app for free.<br />
<br />
To start off here is what you will need:<br />
<br />
1. Basic knowledge of the Android System. Read <a href="http://wirelessthought.blogspot.in/android-basics.html" target="_blank">this post</a>.<br />
.<br />
2. Android SDK which can be <a href="http://developer.android.com/sdk/index.html?utm_source=weibolife" rel="nofollow" target="_blank">downloaded here</a><br />
<br />
3. JAVA programming language. If you don't know that, don't worry. This blog will help you cope with that.<br />
<br />
Once you are done with the above requisites, you are all set to learn how to develop your own android application. Keep following this blog.<br />
<br /></div>
priyankahttp://www.blogger.com/profile/13978896481000985823noreply@blogger.com0tag:blogger.com,1999:blog-4628883243511025261.post-90933770237787532222014-01-28T14:46:00.001+05:302014-02-19T16:21:40.345+05:30THE ANDROID APPLICATION FRAMEWORK<div dir="ltr" style="text-align: left;" trbidi="on">
<div style="text-align: left;">
<span style="font-family: inherit;">Welcome back, to the Basics of Android guide. Here you are going to learn Android free.</span></div>
<div style="text-align: left;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
</div>
<div style="line-height: 150%; margin-bottom: 0cm; text-align: left;">
<span style="color: black; font-family: inherit;">In
my <a href="http://wirelessthought.blogspot.com/2014/01/the-android-stack.html" target="_blank">previous
post</a> I had given an overview of the android system. Now,
that we are familiar with the stack, let's take a closer look at the
application framework. </span></div>
<div style="line-height: 150%; margin-bottom: 0cm; text-align: left;">
<span style="color: black; font-family: inherit;"><br /></span></div>
<div style="line-height: 150%; margin-bottom: 0cm; text-align: left;">
<span style="font-family: inherit;"><span style="color: black;">In software systems, we often across situations where more than one module needs to perform the same task. For such tasks we generally have a library of reusable code</span><span style="color: black;"> </span><span style="color: black;">which can be invoked from any module. This helps us eliminate repetitive code and also minimize binary size. The Android Application Framework helps us do exactly that.</span></span></div>
<div style="line-height: 150%; margin-bottom: 0cm; text-align: left;">
<span style="color: black; font-family: inherit;"><br /></span></div>
<div style="line-height: 150%; margin-bottom: 0cm; text-align: left;">
<span style="color: black; font-family: inherit;">Application
Framework as we saw earlier, is above the native libraries and the
Android runtime system. It consists of pre-installed blocks of
software which various applications can use. </span></div>
<div style="line-height: 150%; margin-bottom: 0cm; text-align: left;">
<span style="color: black; font-family: inherit;"><br /></span></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://4.bp.blogspot.com/-qHZusCSyMyA/UudsVMylBOI/AAAAAAAAG9c/cwxftE6QDWs/s1600/framework.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: inherit;"><img alt="Application framework layer of Android Stack" border="0" src="http://4.bp.blogspot.com/-qHZusCSyMyA/UudsVMylBOI/AAAAAAAAG9c/cwxftE6QDWs/s1600/framework.png" height="112" title="Application framework of Android" width="640" /></span></a></div>
<div style="line-height: 150%; margin-bottom: 0cm; text-align: left;">
<span style="color: black; font-family: inherit;"><br /></span></div>
<div style="line-height: 150%; margin-bottom: 0cm; text-align: left;">
<span style="color: black; font-family: inherit;">Let us take a look at some of its blocks,and try to understand how this framework facilitates re-usability</span></div>
<blockquote class="tr_bq" style="text-align: left;">
<span style="font-family: inherit;"><span style="color: black;"><b>Package Manager</b> : </span><span style="line-height: 150%;">contains data about all the
applications
installed on the device</span></span> </blockquote>
<blockquote class="tr_bq" style="text-align: left;">
<span style="font-family: inherit;"><span style="color: black;"><br /></span></span>
<span style="font-family: inherit;"><span style="color: black;"><b>Activity Manager </b>: Manages the life cycle of an Application.</span></span> </blockquote>
<blockquote class="tr_bq" style="text-align: left;">
<span style="font-family: inherit;"><span style="color: black; line-height: 150%;"><b>Window Manager</b> : </span><span style="line-height: 24px;">manages the many windows of the </span><span style="line-height: 24px;">applications. An application may need more than one window. Say ta main window, a menu window, another sub-menu window and so on.</span></span> </blockquote>
<blockquote class="tr_bq" style="text-align: left;">
<span style="font-family: inherit;"><span style="line-height: 24px;"><b>View System</b>: contains common UI related elements such as pop-ups, buttons and icons.</span></span> </blockquote>
<blockquote class="tr_bq" style="text-align: left;">
<span style="font-family: inherit;"><span style="line-height: 24px;"><b>Content Provider</b> : </span>database for an application to store and retrieve data and let other app access its data. This facilitates inter application data sharing.<br /></span></blockquote>
<div style="text-align: left;">
<span style="font-family: inherit;">Similarly the other blocks Location, Notification, Telephony and Resource Managers provide services, as suggested by their names, to the top application layer. We will learn about them gradually.</span></div>
<div class="separator" style="clear: both; text-align: center;">
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<div class="separator" style="clear: both; text-align: center;">
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priyankahttp://www.blogger.com/profile/13978896481000985823noreply@blogger.com0tag:blogger.com,1999:blog-4628883243511025261.post-75046953936591339872014-01-23T13:41:00.000+05:302014-02-04T12:36:38.635+05:30BASICS OF ANDROID <div dir="ltr" style="text-align: left;" trbidi="on">
To learn how to develop a Mobile Application using Android, We need to first understand the basics of Android. This and the following few posts will provide a guide or tutorial for Android mobile app development.<br />
<br />
<u>Overview of The Android Stack </u><br />
<br />
The Android is a platform which support mobile devices such as phones and tablets. It has several layers that manage everything from sensors to the applications you see on the screen (and the android app that you are going to develop).<br />
<br />
Shown below is a representation of Android stack<br />
<br />
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="http://mahalelabs.files.wordpress.com/2013/03/androidstack-1.jpg" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="android stack diagram" border="0" src="http://mahalelabs.files.wordpress.com/2013/03/androidstack-1.jpg" title="WHAT ANDROID STACK CONTAINS" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The Android System Stack</td></tr>
</tbody></table>
<br />
Android has:<br />
<ul style="text-align: left;">
<li>LINUX KERNEL as the bottom layer</li>
</ul>
<ul style="text-align: left;">
<ul>
<li>which provides the operating system services.</li>
</ul>
</ul>
<ul style="text-align: left;">
<li>THE SYSTEM LIBRARIES and the ANDROID RUNTIME SYSTEM above it</li>
</ul>
<ul style="text-align: left;">
<ul>
<li>C/C++
libraries that make many operations easier for the programmer and
also help improve performance</li>
<li>ANDROID
RUNTIME : JAVA libararies and the Dalvik Virtual Machine (Explained below)</li>
</ul>
</ul>
<ul>
<li><div align="LEFT" style="margin-bottom: 0cm;">
<span style="color: black;"><span style="font-family: Times New Roman;">next
up is a rich APPLICATION FRAMEWORK</span></span></div>
</li>
</ul>
<ul>
<ul>
<li><div align="LEFT" style="margin-bottom: 0cm;">
<span style="color: black;"><span style="font-family: Times New Roman;">reusable
software that can be used by many applications, like buttons and
icons</span></span></div>
</li>
</ul>
<ul>
<li><div align="LEFT" style="margin-bottom: 0cm;">
<span style="color: black;"><span style="font-family: Times New Roman;"><a href="http://wirelessthought.blogspot.com/2014/01/the-android-application-framework.html" target="_blank">Deeper Look into Application Framework</a></span></span></div>
</li>
</ul>
</ul>
<ul>
<li><div align="LEFT">
<span style="color: black;"><span style="font-family: Times New Roman;">and at the top of all these the APPLICATIONS that we use.</span></span><span style="font-family: Times;"> This is the interface of the USER and the rest of the android system</span></div>
</li>
</ul>
<div style="text-align: left;">
<div style="text-align: left;">
<u>THE DALVIK VIRTUAL MACHINE (DVM)</u></div>
<blockquote class="tr_bq">
Android programs are generally written in JAVA. However they are not executed bythe JAVA virtual machine. They actually run on the Dalvik Virtual Machine. </blockquote>
<blockquote class="tr_bq">
Applications programmed in JAVA are compiled using a JAVA compiler to generate the JAVA byte code. In order to make it executable in the DVM, the JAVA bytecode is converted to a DEX format using appropriate tools. This DEX code, with other packages of the application, is installed on the target device and when run, it is executed by the Dalvik Virtual Machine. </blockquote>
<blockquote class="tr_bq">
<b>WHY DVM and NOT JVM?</b><br />
JVM is not designed to run on mobile devices where resources like CPU, memory and power are limited. DVM is particularly designed for this purpose. Hence while developing an Android app, the developer has to worry less about the constrained resources.</blockquote>
</div>
<div style="text-align: left;">
Next, Let us have a <a href="http://wirelessthought.blogspot.in/2014/01/the-android-application-framework.html" target="_blank">closer look at the android application framework</a>.<br />
<br />
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priyankahttp://www.blogger.com/profile/13978896481000985823noreply@blogger.com0tag:blogger.com,1999:blog-4628883243511025261.post-38123066046326898002014-01-02T14:14:00.000+05:302014-02-07T17:52:34.355+05:30COMPILER Basics for Dummies- 1<div dir="ltr" style="text-align: left;" trbidi="on">
<div style="text-align: left;">
<span style="font-size: x-small;"><span style="font-weight: normal;"><i>Starting from this article, we are going to present a free guide and introduction to the principles of Compiling a program. Beginners can read it as a brief guide to get started on Compilers.</i></span><span style="font-weight: normal;"><i>Going forward we will be looking into GNU's GCC. I am avoiding too much details and providing information enough for Freshers/ Engineers and Undergrads to understand compilers.</i></span></span></div>
<br />
A compiler is a program that reads another program, called the source code ( written in a particular high level programming language) and converts it into, a low level language.<br />
<br />
By low level I mean either Assembly or machine code.<br />
<a name='more'></a>Also, as a part of the compilation process, the compiler will report the errors present in the source code.<br />
<br />
It is but obvious, that this compilation process can not happen in a single step. That is to say, the compilation process in itself is broken up into a series of processes. In most cases, compilation process can be grouped into two parts: Analysis and Synthesis.<br />
<br />
While Analyzing, the source code is converted to an intermediate representation.<br />
Lets us briefly look at how this happens:<br />
<ul style="text-align: left;">
<li><span style="background-color: #f3f3f3;">Lexical Analysis : </span></li>
<ul>
<li><span style="background-color: #f3f3f3;">Stream of characters from Source program are scanned from left to right. </span></li>
<li><span style="background-color: #f3f3f3;">Meaningful Tokens are identified based on programming language rules.</span></li>
<li><span style="background-color: #f3f3f3;">spaces are eliminated</span></li>
<li><span style="background-color: #f3f3f3;">Parsing : grouping of tokens to generate PARSE TREE</span></li>
</ul>
</ul>
<ul style="text-align: left;">
<li><span style="background-color: #f3f3f3;">Syntax Analysis</span></li>
<ul>
<li><span style="background-color: #f3f3f3;">Check syntax as per programming language specs (type casting etc.)</span></li>
<li><span style="background-color: #f3f3f3;">convert parse tree into SYNTAX TREE</span></li>
</ul>
</ul>
<ul style="text-align: left;">
<li><span style="background-color: #f3f3f3;">Semantic Analysis</span></li>
<ul>
<li><span style="background-color: #f3f3f3;">check for semantic errors</span></li>
</ul>
</ul>
<div>
Although an error can occur at any stage, the syntax and semantic analyzing phases generally detect most of the errors in the program.</div>
<div>
<br /></div>
<div>
Based on the above we arrive at some building blocks of a compiler.</div>
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</div>
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This is early part of the compiler as shown above is commonly called the FRONT END.</div>
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priyankahttp://www.blogger.com/profile/13978896481000985823noreply@blogger.com0tag:blogger.com,1999:blog-4628883243511025261.post-17377406581618160912013-11-30T13:46:00.000+05:302014-02-28T12:55:59.673+05:30Frequency Reuse with Cellular Topology<div dir="ltr" style="text-align: left;" trbidi="on">
<span style="background-color: white; font-family: inherit; line-height: 19.200000762939453px;">Start this tutorial from : <a href="http://wirelessthought.blogspot.in/2012/08/more-or-less-its-wireless.html">I<span id="goog_374979825"></span>ntroductio<span id="goog_374979826"></span>n</a></span><br />
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<span style="background-color: white; font-family: inherit; line-height: 19.200000762939453px;">Primitively mobile networks </span><span style="background-color: white; line-height: 19.200000762939453px;"> </span><span style="background-color: white; line-height: 19.200000762939453px;">(that should probably be called the 0g mobile network such as IMTS),</span><span style="background-color: white; font-family: inherit; line-height: 19.200000762939453px;">were designed like TV networks... one very powerful base station catered to a large area. </span><br />
<span style="font-family: inherit;"><br />
<span style="line-height: 19.196969985961914px;">The IMTS by AT&T for instance in New York, had 12 channels only. This means that at a given time only 12 calls could be active. Because of limited channels, AT&T had to limit subscribers to 2000. On an average users had to wait around 20 minutes before there calls could be placed.</span></span><br />
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<span style="background-color: white; font-family: inherit;"><span style="line-height: 19.196969985961914px;">This user capacity limitation was overcome by using a </span><span style="line-height: 19.196969985961914px;">Cellular Topology</span></span><br />
<span style="background-color: white; font-family: inherit;"><span style="line-height: 19.200000762939453px;"><br /></span><span style="line-height: 19.200000762939453px;">A</span><span style="line-height: 19.196969985961914px;"> land area to be covered is divided into regular shaped cells</span><span style="line-height: 19.196969985961914px;">(as big as 10-15 miles),</span><span style="line-height: 19.200000762939453px;"> which can be hexagonal, square, circular or some other regular shapes.Hexagonal cells are conventional because hexagons best resemble a circle. (as a BTS would radiate around itself in more or less a circular radius)</span></span></div>
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<tr><td style="text-align: center;"><a href="http://www.privateline.com/Cellbasics/sevencellcluster.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><span style="font-family: inherit;"><img alt="Cluster of Cells" border="0" src="http://www.privateline.com/Cellbasics/sevencellcluster.gif" height="320" title="Cluster in Cellular Topology" width="312" /></span></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: inherit; font-size: small;">A cluster of cells</span></td></tr>
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<span style="background-color: white; font-family: inherit;"><span style="line-height: 19.200000762939453px;">Each cell is </span><span style="line-height: 19.200000762939453px;">served by one or more fixed-location </span>transceiver<span style="line-height: 19.200000762939453px;">, known as a </span>cell site<span style="line-height: 19.200000762939453px;"> or </span>base station<span style="line-height: 19.200000762939453px;">. A mobile device would communicate with a cell-site most closest to it. </span><span style="line-height: 19.200000762939453px;">Every</span><span style="line-height: 19.200000762939453px;"> </span>radio base stations transmits/receives information in its cell at a particular frequency range from <i style="line-height: 19.200000762939453px;">f</i><sub style="line-height: 1em;">1</sub><span style="line-height: 19.200000762939453px;"> - </span><i style="line-height: 19.200000762939453px;">f</i><sub style="line-height: 1em;">6</sub> <span style="line-height: 19.200000762939453px;">. The group of frequencies can be reused in other cells, provided that the same frequencies are not reused in adjacent neighboring cells as that would cause </span>co-channel interference<span style="line-height: 19.200000762939453px;">.</span></span><br />
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<span style="font-family: inherit;"><span style="line-height: 19.196969985961914px;">How capacity is improved by cellular topology?</span></span></h4>
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<span style="line-height: 19.196969985961914px;">In IMTS : </span></span><br />
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<span style="font-family: inherit;"><span style="line-height: 19.196969985961914px;">we can think the entire area A as one big cell with one BTS. </span></span></blockquote>
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<span style="font-family: inherit; line-height: 19.196969985961914px;">Let total number of channels = 14</span><span style="font-family: inherit; line-height: 19.196969985961914px;">Number of Active calls that can be supported in area A = 14</span></blockquote>
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<span style="line-height: 19.196969985961914px;">In Cellular: </span></span><br />
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<span style="font-family: inherit;"><span style="line-height: 19.196969985961914px;">Let A be divided in 10 clusters</span></span></blockquote>
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<span style="font-family: inherit; line-height: 19.196969985961914px;">No. Of cells in one cluster = 7 </span><span style="font-family: inherit; line-height: 19.196969985961914px;">Number of channels per cluster = 14/7 = 2</span><span style="font-family: inherit;"><span style="line-height: 19.196969985961914px;"><br /></span></span><span style="font-family: inherit;"><span style="line-height: 19.196969985961914px;">Number of channels in area A = (14*10)/7=20</span></span><span style="font-family: inherit;"><span style="line-height: 19.196969985961914px;">Number of Active calls that can be supported in area A = 20</span></span></blockquote>
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This was a short description of channel multiplication using frequency reuse. Now, that we know basic concepts behind cellular topology, we shall for now, stop here. There's a lot more to frequency re-use and cell planning which is a major field research and application. Cell planning is a science in itself.</span><br />
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priyankahttp://www.blogger.com/profile/13978896481000985823noreply@blogger.com0tag:blogger.com,1999:blog-4628883243511025261.post-32230554085523429822013-11-04T11:17:00.000+05:302014-02-28T12:52:53.639+05:30Mobile Communication Systems - Basics<div dir="ltr" style="text-align: left;" trbidi="on">
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<span style="font-family: Times, 'Times New Roman', serif;">Now, let us see what makes up a communication system. A very basic components are</span><br />
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<li>SOURCE the beginning point </li>
<li>INFORMATION or DATA to be conveyed</li>
<li>CARRIER or MEDIUM that will take data from source to destination</li>
<li>RECIPIENT</li>
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<span style="font-family: Times, 'Times New Roman', serif;">Now, the very important requirement for communication, is a MEDIUM through which information will flow from the SOURCE to the RECIPIENT. For wireless systems this medium is called the CARRIER, which consists of waves of given frequency. For mobile telephony, RADIO FREQUENCY range is used.</span></div>
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<span style="font-family: Times, Times New Roman, serif;">The carrier can be modulated in a variety of ways to embed data/information into it. It is then signaled from a transmitter. The receiving end has a receiver that captures this signals and demodulates it to decipher the embedded data/info/message.</span></div>
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<span style="font-family: Times, Times New Roman, serif;">Since there are so many different mobile carriers, to avoid exchange of signals and interference, each carrier can use only an allotted frequency range from the spectrum. That is why the radio spectrum has become a very valuable asset.</span></div>
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<span style="font-family: Times, Times New Roman, serif;">MOBILE NETWORKS</span></h3>
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<span style="font-family: Times, Times New Roman, serif;"><span style="background-color: white; line-height: 19.200000762939453px;">A </span><span style="background-color: white; line-height: 19.200000762939453px;">mobile network</span><span style="background-color: white; line-height: 19.200000762939453px;"> is a </span>radio<span style="background-color: white; line-height: 19.200000762939453px;"> network distributed over huge land areas. Terminal devices or mobile phones can move around in this land areas and still communicate.</span></span><br />
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<span style="background-color: white; font-family: Times, Times New Roman, serif; line-height: 19.196969985961914px;">In order to support communication between subscribers we need a pair of RF channels <span style="background-color: white;">per active call. </span></span><span style="background-color: white; font-family: Times, 'Times New Roman', serif; line-height: 19.196969985961914px;">1 Channel requires atleast two frequencies, one for forward link and one for reverse link.</span><br />
<span style="font-family: Times, Times New Roman, serif;"><span style="background-color: white; line-height: 19.196969985961914px;"><br /></span><span style="background-color: white; line-height: 19.196969985961914px;">In large cities where operators could have thousands of subscribers, we would require a large number of channels. A given base station can transceive only at a given frequency range, and the number of channels would be limited. </span><span style="background-color: white; line-height: 19.196969985961914px;">Also there is a </span><span style="background-color: white; line-height: 19.196969985961914px;">limit to availability of spectrum. </span></span><br />
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<a href="http://4.bp.blogspot.com/-QS68TmWiNRs/UDTLEPWWQlI/AAAAAAAABSU/_EumzcK1UqQ/s1600/Picture3.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><span style="font-family: inherit;"><img alt="forward and reverse path communication" border="0" src="http://4.bp.blogspot.com/-QS68TmWiNRs/UDTLEPWWQlI/AAAAAAAABSU/_EumzcK1UqQ/s640/Picture3.png" height="456" title="Full duplex wireless mobile communication" width="640" /></span></a></div>
<span style="font-family: Times, Times New Roman, serif;"><span style="background-color: white; line-height: 19.200000762939453px;"><br /></span></span><span style="font-family: Times, Times New Roman, serif;"><span style="background-color: white; line-height: 19.196969985961914px;">If an operators get a 1 MHz band, and has 12 </span><span style="background-color: white; line-height: 19.196969985961914px;">channels to use and only one base station to cover the entire state, then at any given time it could support only 12 active calls at max</span><span style="background-color: white; line-height: 19.196969985961914px;">. To overcome this limitation, you have to create zones of coverage, </span><span style="background-color: white; line-height: 19.196969985961914px;">which are called as cells. </span></span><br />
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READ NEXT : <a href="http://wirelessthought.blogspot.in/2012/08/frequency-reuse-with-cellular-topology.html">Frequency Reuse in Cellular Toplogy</a></div>
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priyankahttp://www.blogger.com/profile/13978896481000985823noreply@blogger.com0tag:blogger.com,1999:blog-4628883243511025261.post-38244903409967214612013-10-24T17:56:00.000+05:302014-02-28T12:27:21.282+05:30More or Less... We're Wireless<div dir="ltr" style="text-align: left;" trbidi="on">
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<span style="font-family: inherit;">You may be wondering why I am posting about Wireless mobile communication systems.</span><br />
<span style="font-family: inherit;">They have been there since decades! </span><span style="font-family: inherit;">What's new about them ?</span><br />
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Well you are right, there's nothing new about them. They have evolved for so many years. </span><br />
<span style="font-family: inherit;">But the interesting thing is they don't stop evolving.. from simply "cellular technology" to 3G, 4G and 5G or the LTE advanced... wireless technology is always renewing.</span><br />
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<span style="font-family: inherit;">This and some more following posts will help you quickly learn how wireless technology evolved and soon you will be up-to-date with recent advances.</span><br />
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<span style="font-family: inherit; font-size: small;">What Qualifies to be called a Wireless Communication System?</span></h4>
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<span style="font-family: inherit; line-height: 19.200000762939453px;">Communication - means transfer of data from one point to another. </span><br />
<span style="font-family: inherit; line-height: 19.200000762939453px;">Any transfer of information between two or more points that are not physically connected by wires is wireless communication. </span><br />
<span style="font-family: inherit; line-height: 19.200000762939453px;"><br /></span>
<span style="font-family: inherit; line-height: 19.200000762939453px;">Therefore, e</span><span style="font-family: inherit;"><span style="line-heightpan: 19.200000762939453px;">ven when you talk to your friend sitting beside you, technically you are communicating "wireless-ly". </span></span><span style="font-family: inherit; line-height: 19.196969985961914px;">But since we are Engineers, let's leave aside these naive examples.</span><br />
<span style="font-family: inherit;"><span style="line-height: 19.196969985961914px;"><br /></span></span>
<span style="font-family: inherit;"><span style="line-height: 19.196969985961914px;">We will consider only technologically advanced wireless data transfer as wireless communication. So, more complex examples of wireless communication systems would be:</span></span><br />
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<span style="font-family: inherit; line-height: 19.200000762939453px;"><span style="font-family: inherit;">Short Distance : TV controlled by remote</span></span></div>
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<span style="font-family: inherit; line-height: 19.200000762939453px;">OR</span></div>
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<span style="background-color: white; font-family: inherit; line-height: 19.196969985961914px;">Long Distance : Space Radio Communication</span></div>
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<span style="font-family: inherit; font-size: small; line-height: 19.196969985961914px;">A Piece of Fun Fact</span></h4>
<span style="font-family: inherit;"><span style="line-height: 19.196969985961914px;">(click on image for magnified view)</span></span><br />
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<span style="font-family: inherit;"><span style="line-height: 19.200000762939453px;">The world's first wireless telephone conversation occurred in 1880, when </span><a href="http://inventors.about.com/od/pstartinventions/a/photophone.htm" rel="nofollow" target="_blank">Alexander Graham Bell</a><span style="line-height: 19.200000762939453px;"> and </span>Charles Sumner Tainter<span style="line-height: 19.200000762939453px;"> invented and patented </span><i>photophone</i><span style="line-height: 19.200000762939453px;">, a telephone that conducted audio conversations wirelessly over modulated </span>light beams<span style="line-height: 19.200000762939453px;">. </span></span><br />
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<a href="http://www.assistivelistening.net/sc_assistivetech_info/sc_agbell_photophone.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><span style="color: black; font-family: inherit;"><img alt="photophone" border="0" src="http://www.assistivelistening.net/sc_assistivetech_info/sc_agbell_photophone.jpg" title="Alexander Graham Bell's Photophone" /></span></a></div>
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<span style="font-family: inherit;"><span style="line-height: 19.200000762939453px;">At that time this invention was practically useless. Decades later </span><span style="line-height: 19.200000762939453px;">the photophone's principles found their first practical applications in </span>military communications<span style="line-height: 19.200000762939453px;"> and later in </span>fiber-optic communications<span style="line-height: 19.200000762939453px;">.</span></span></div>
<span style="font-family: inherit;"><span style="line-height: 19.200000762939453px;">This happened in that primitive era when </span>electricity was a luxury<span style="line-height: 19.200000762939453px;">, and </span>lasers<span style="line-height: 19.200000762939453px;"> had not even been conceived of in </span>science fictions. The transmitter required a clear line-of-sight with the receiver. (As light rays were carrying the info). Another requirement was sun-light and good weather to operate.</span><br />
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<span style="line-height: 19.196969985961914px;"><span style="font-family: inherit; font-size: small;">Evolution milestones of Mobile Communication Technology</span></span></h4>
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<span style="font-family: inherit; line-height: 19.196969985961914px;">The following map summarizes the evolution of cellular technology generations.</span><br />
<span style="font-family: inherit; line-height: 19.196969985961914px;">(click on image for magnified view)</span></div>
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<tr><td class="tr-caption" style="text-align: center;"><span style="font-family: inherit; font-size: small;">Summary of Cellular Technology Generations</span><br />
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<span style="font-family: inherit; line-height: 19.196969985961914px;">Although there are so many different wireless technologies from WLAN and Bluetooth to radio space communications, for this series we will be limiting ourselves to Wireless Mobile communications, as that is the most widely used wireless technology these days.</span></div>
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<span style="font-family: inherit;"><b> </b></span><span style="color: black; font-family: inherit; text-align: center;">NEXT READ:<b> </b></span><a href="http://wirelessthought.blogspot.in/2012/08/mobile-communication-system.html" target="_blank">MOBILE COMMUNICATION SYSTEM</a></div>
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<span style="color: red; font-family: inherit;">Please leave us a comment</span></div>
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