Difference between pages "TDMA" and "Libqcow"

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{{Wikify}}
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{{Infobox_Software |
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  name = libqcow |
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  maintainer = [[Joachim Metz]] |
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  os = [[Linux]], [[FreeBSD]], [[NetBSD]], [[OpenBSD]], [[Mac OS X]], [[Windows]] |
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  genre = {{Disk imaging}} |
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  license = {{LGPL}} |
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  website = [http://code.google.com/p/libqcow/ code.google.com/p/libqcow] |
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}}
  
'''TDMA - Time Division Multiple Access'''
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The '''libqcow''' package contains a library and applications to read the [[QCOW_Image_Format | QEMU Copy-On-Write (QCOW) image]] format.
  
TDMA (Time Division Multiple Access), has the largest network in the US.
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== Tools ==
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The '''libqcow''' package contains the following tools:
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* '''qcowinfo''', which shows the information about QCOW files.
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* '''qcowmount''', which FUSE mounts QCOW image files.
  
TDMA is a digital wireless communication method allowing many users to access a single radio frequency without interference.  Every individual user is given a unique time slot within each channel. 
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== Examples ==
  
'''Why use TDMA?'''
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FUSE mounting a QCOW image (libqcow 20111009 or later)
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<pre>
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qcowmount image.qcow mount_point
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</pre>
  
It increases the efficiency of transmission and offers a number of other advantages.  A major pro is it can be easily adapted to transmission of data as well as voice communication.  It offers the ability to carry date rates of 64 kbps to 120 mbps, which enables options of communication such as fax, voiceband data, sms, as well as bandwidth intensive apps.  TDMA allows the user to have extended battery life since the mobile is only transmitting a portion of the time during conversations.  Furthermore, it is the most cost effective technology for upgrading a current analog system to digital.
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== History ==
  
'''How it works:'''
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Libqcow was created by [[Joachim Metz]] in 2010.
  
It’s necessary for TDMA to rely upon that fact that the audio signal has been digitized.  These signals are divided into a number of milliseconds.  TDMA is also the access technique used in the European digital standard, GSM, and the Japanese digital standard, personal digital cellular (PDC). The reason for choosing TDMA for all these standards was that it enables some vital features for system operation in an advanced cellular or PCS environment. Today, TDMA is an available, well-proven technique in commercial operation in many systems.
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== Also See ==
A single channel can carry all four conversations if each conversation is divided into relatively short fragments, is assigned a time slot, and is transmitted in synchronized timed. 
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[[QCOW_Image_Format | QEMU Copy-On-Write (QCOW) image format]]
  
 
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== External Links ==
 
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* [https://code.google.com/p/libqcow/ Project site]
'''Pros & Downfaults:'''
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* [https://code.google.com/p/libqcow/wiki/Building Building libqcow and tools from source]
 
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* [https://code.google.com/p/libqcow/wiki/Mounting Mounting a QCOW image]
TDMA can be wasteful of bandwidth because time slots are allocated to specific conversations whether or not anyone was speaking at the given moment.  There is an enhanced version however, EDTMA, which attempts to correct this problem.  Unlike TDMA which waits to determine whether a subscriber is transmitting, ETDMA assigns subscribers using a dynamic method.  The data is sent through pauses which normal speech contains.  If the subscriber has something they would like to transmit, it is placed as one bit in the buffer queue.  The system then scans the buffer and notices the user has something to transmit, allocating the bandwidth accordingly.  However, if there is nothing to transmit, it goes to the next subscriber.  This technique can be 10 times more efficient as analog transmission of TDMA. 
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'''Cell Phone Providers:'''
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There are several cell phone companies competing to sell their phones and advertise their network coverage area.  They will primarily be competing within two categories:  TDMA and CDMA.  The pros and cons of TDMA have been mentioned, and the companies that offer TDMA are the following:  AT&T, Cingular, Nextel, T-Mobile.  The companies that support CDMA are:  ALLTEL, Amp'd Mobile, Cricket Wireless, ESPN, Quest, Sprint, Verizon, Virgin Mobile.  As we can see, more companies are supporting CDMA.  The question that arises is, what makes the two so different? 
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'''TDMA Vs. CDMA'''
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TDMA is better for international plans and debately has better battery life.  CDMA claims it has better battery life and coverage, however, Cingular is supposed to have the best coverage area and that is TDMA.  All of this started however ever since CDMA was introduced in 1989, and the wireless world has been in debate over merits of TDMA and CDMA.  Those who are for CDMA have claimed that its technology has bandwidth efficiency of up to 13 times that of TDMA and between 20 to 40 times that of analog transmission.  Furthermore, CDMA lovers say its spread spectrum technology is more secure and offers higher transmissin quality than TDMA because of TDMA's increased resistance to multipath distortion.   
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Those who favor TDMA point out that there has been no successful major trial of CDMA technology that supports the capacities it claims.  Not to mention, theoretical improvements in bandwidth efficiency claimed CDMA is now being approached by enhancements to TDMA technology.  TDMA's evolution allows capacity increases of 20 to 40 fold over analog in the near future.  CDMA is a very expensive technology that needs $300,000 per base station, compared to $80,000 for TDMA.  Lastly, TDMA is the proven leader as the most economical digital migration path for existing AMPS networks.  No one has the final word in this debate, however, it is evident that TDMA will remain the dominant technology in the wireless market. 
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'''References'''
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[http://en.wikipedia.org/wiki/Time_division_multiple_access TDMA]
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[http://www.iec.org/online/tutorials/tdma/topic04.html]
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[http://www.cellphoneinfo.com/index.html]
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Latest revision as of 00:29, 15 July 2013

libqcow
Maintainer: Joachim Metz
OS: Linux, FreeBSD, NetBSD, OpenBSD, Mac OS X, Windows
Genre: Disk imaging
License: LGPL
Website: code.google.com/p/libqcow

The libqcow package contains a library and applications to read the QEMU Copy-On-Write (QCOW) image format.

Contents

Tools

The libqcow package contains the following tools:

  • qcowinfo, which shows the information about QCOW files.
  • qcowmount, which FUSE mounts QCOW image files.

Examples

FUSE mounting a QCOW image (libqcow 20111009 or later)

qcowmount image.qcow mount_point

History

Libqcow was created by Joachim Metz in 2010.

Also See

QEMU Copy-On-Write (QCOW) image format

External Links