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18-07-2010, 01:41 PM
I am Kalyani Nawathe. I want full seminar report on "Echo Cancellation in Wireless Communication".
My email ID is kalyani.nawathe[at]gmail.com
I will be very glad if u send me the full seminar report of the topic "Airborne Internate".
please send me fast it is urgent for me.
Thank you
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I am Sreejith.S.J. I full seminar report on "Echo cancellation in wireless communication."
My e-mail id is sreejith_panayara[at]yahoo.in
I will be very glad if send me the report of the topic "Echo cancellation in wireless communication".
Please send me fast it is urgent for me.
Thank you.
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Summary
The design of high quality echo-cancelation schemes for wireless networks is a challenging task. Even though there are the limitations of time-varying channel conditions and limited bandwidth, good quality should be maintained. This is a challenging task. bit rate, delay, power consumption, complexity, and quality of coded speech are the parameters that must be considered while designing the system. The network protocols determine the Available bandwidth. bandwidth-efficiency considerations are the major driving forces behind echo cancellation. the target application being telephonic where the channel does not vary considerably with time and the Signal-to-Noise (SNR) is relatively high
A technique for nonlinear echo cancellation in wireless networks
The echo cancellation technique in wireless telephones mostly uses the echo canceller to be placed in the wireless handset.In this system , the processing is done in the handsets themselves which require the costlier handsets and more power consumption. By using the echo canceller in the base station, this problem can be solved. nonlinear echo is generated in a wireless network and the speech codecs present at the base station produce nonlinear distortion in the mobile signal.Here, an echo cancellation technique based on adaptive Volterra filters has been proposed for cancellation of nonlinear echo due to codecs.
for this paper, visit:
http://ieeexplore.ieeexpl/mostRecentIssu...umber=9787
for further details, visit:
http://shortstoryexpressDSPwhitepaper.PDF
http://ee.ucla.edu/~spapl/projects/codin...references
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echo cancellation in wireless communicetion
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ABSRACT
In this paper, the echo cancellation network, there. Different types causes, the process of echo cancellation and controlling the echo are Present. This paper also discuss the nature of echo and how echo cancellation technique is helpful in improving the quality standards of mobile call. The echo cancellation technique reduces the background noise and remove hybrid and acoustic echo before any transcoder process.
INTRODUCTION
Now a days the use of wireless phone are increases. This wireless Phones becomes the essential part of the communication network. Day to day the Network get expand and become more complicated because of the competion between the wireless carrier. The echo is generated during the transmission in the network. In addition they eliminate double talk capabilities and greatly reducing the ability to achieve the natural conversation. An echo cancellation in such system has to deal with the cancellation of acoustic (multi-path)echoes generated with each syllables of speech.
HISTORY OF ECHO CANCELLATION
The late 1950s marked the birth of echo control in the telecommunication. Industry with the development of the first echo suppression devices. Although echo suppressers reduced echo caused by transmission problems in the network, they also reduced in choppy first syllables and artificial volume adjustment. Echo cancellation theory was developed in early 1960s by AT &T Bell Labs, by COMSAT Tele Systems. COMSAT design the first analog echo canceller system to demonstrate feasibility and performance of satellite communication networks. These systems were not commercially viable, however, because of their size and manufacturing costs.
TYPES OF ECHO
a) Acoustic echo
Acoustic echo is generated with analog and digital handsets, With the degree of echo related to the type and quality of equipment used. This form of echo is produced by poor voice coupling between erapiece and microphone in handsets and hands-free devices. Further voice degradation is caused as a voice compressing encoding /decoding devices (vocoders) process the voice paths within the handsets and in wireless networks. This results in returned echo signals with highly variable properties. Acoustic echo was first encountered with the early video/audio conferencing studios and –as figure 1 shows-now also occurring typical mobile situations, such as peoples are driving theirs cars. In this situations sound from a loudspeakers is heard by a listener, as intented. However, this same sound also is picked up by the microphones, both directly and indirectly, after bouncing off the roofs, windows, and seats of the car.
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