International Journal of Engineering Trends and Technology (IJETT) – Volume 26 Number 1- August 2015
Echo Canceller Simulation for a Network Extender
Ms.Akhila 1, Mr.Bhaskar Reddy 2, Mr.Kesavarao Vetapalem 3
Pg student
Dept of Electronic and Communication, Qis College OF Engineering And Technology, Ongole ,
Prakasam District,Andhra Pradesh,India .
Professor
Dept of Electronic and Communication, Qis College OF Engineering And Technology,
Ongole ,Prakasam District,Andhra Pradesh,India.
Member technical staff-II, FidZeal Technologies Pvt Ltd,Banglore,India .
Abstract — Echo is one of the problem in network
repeaters which causes loss of information in order to
reduce it for better usage performance of network
repeaters we use echo cancellers .Echo cancellers
may also be used in radio frequency repeaters,
network extenders or any other kind of signal
boosters. Eventually, this not only improves the signal
strength and eliminates the echo/noise present in the
communication path, it also helps in improving the
data transfer rate. Here we are introducing a echo
cancellation algorithm
which increased the
performance of a portable network extender.
Keywords — Network extender, channel
estimation, Equalization .
Introduction
In order to overcome the problem of poor
cell reception of network in some Remote /Inside
Home where it is far from base station we
implemented the network extender with the perfect
echo cancellation algorithm and gain control so that
every person can achieve a good improved call
performance in cell phones. Network extender takes
the existed primary network as input and boosts the
signal converts to a second network given as output to
be used by the mobile phones in homes and
offices .Network extender usage not only improves
call signal performance it also improves data signal
rate. The newly improved network extender is a plug
and play device without the external antennas when
compared with the previous network extenders
present in market which makes easy usage of
equipment when ever needed.
I. LITERATURE SURVEY
A general problem in telephony is the
occurrence of an acoustic echo. It occur through
poorly screened cables or insufficient bandwidth.
ISSN: 2231-5381
Most echo laden telecom transactions are quickly
abandoned by the participants. So we use Echo
cancellation algorithms which
implemented in
software and hardware (echo cancellers).
Echo cancellers may be used in radio
frequency repeaters, network extenders or any other
kind of signal boosters. Eventually, this not only
improves the signal strength and eliminates the
echo/noise present in the communication path, it also
helps in improving the data transfer rate.
A wireless repeater/ network extender
receives an existing primary network as signal and
rebroadcasts it to create a second network with
improved performance and transmits the newly
generated signal so that it can be used by cell phones.
II. NETWORK EXTENDER
The network extender which receives signal
from the nearest base station boosts the signal using
the echo cancellation block and gain control block and
transmits the boosted signal to the user equipment or
mobile.
Figure I: RF Scenario, Downlink
http://www.ijettjournal.org
Page 6
International Journal of Engineering Trends and Technology (IJETT) – Volume 26 Number 1- August 2015
A. Gain control
The transceiver used for gain control in this
network extender uses manual gain control mode
operation where we will set parameters which can
effect the total gain .
5
4
2
1
0
0
4
3
3
25
45
60
R/Tx0L(A)
R/Tx1H(A)
R/Tx0H(A)
Table I: Ant. port for different bands
D. Performance parameters
B. Echo cancellation
The performance of the Echo Cancellation
algorithm can be calculated using the two
parameters
Echo cancellation is one of the module in network
extender and this module performs the cancellation of
the echo in the system. The sub components involved
in this algorithm are
1)BER (Bit Error Rate).
Correlation
This module will do the correlation between
received signal and reference signal. Here we use
Zadoff-Chu sequence as reference signal, the
correlation method will be used to estimate the
delay in the echo path.
If BER is found zero, i.e The data transmited
received properly.
is
2) EVM (Error Vector Magnitude).
EVM should be between < 15% for the better
signal to receive with less error.
Channel estimation
The channel in the echo path will be estimated
from the received samples and the buffered signal. The
channel estimates will be updated during the
calibration. The channel estimates will be stored in the
buffer and the average channel estimates will be used
for equalization.
III. CONCLUSIONS
In this paper we simulated the echo
cancellation algorithm in a echo canceller for the
improved performance of network extender which
found a way for the better call performance even at the
hilly areas where the normal base station signal does
not give much signal.
Equalization
REFERENCES
[1] “Cellular Antenna Requirements”, Dragon Project Network
The equalization of the received data will be
done by zero forcing equalization method. The
averaged channel estimates and buffered signal will be
used for the equalization. The estimated delay will be
applied on the buffered signal and equalized with the
average channel estimates.
Extension Device, 5BARz International, Inc., Tom Bilotta.
[2] John G. Proakis, "Digital Communication", McGraw Hill,
4th edition, 2001.
[3] Bernard Sklar, "Digital Communication - Fundamental and
[4]
[5]
C. Bands
The different bands used in the network extender
are 12,13,5,4,2 where the antenna ports for the local
side and donor side are different for each bands. Here
we can clearly see in the below table where the
Downlink and Uplink bands are clearly seen here
[6]
[7]
[8]
BAND
12
13
Antenna Port
Donor
Local
2
5
2
5
ISSN: 2231-5381
BW
(MHz)
17
10
MAX2580
Ant.Port
R/Tx1L(A)
R/Tx1L(A)
applications", Pearson education (Asia), Pvt. Ltd., 2nd edition,
2001.
Digital communications, Simon Haykin, John Wiley India
Pvt. Ltd, 2008.
John G. Proakis, Digital signal processing, principles,
algorithms , and application.
[9] K. M. Nasr, J. P. Cosmas, M. Bard and J. Gledhill,
“Performance of an Echo Canceller for On-Channel Repeater
in DVB-T/H Networks”. IEEE Transcation on Broadcasting,
vol. 53, no.3, Sep.2007: 609-618.
Munjal, A., Aggarwal, V. & Singh, G., “RLS
Algorithm for Acoustic Echo Cancellation” COIT, March,
2008.
Huston, M.,”Acoustic Echo Cancellation using Digital Signal
Processing”, PhD thesis, the school of information,
technology and Electrical Engineering, The University of
Queensland, 2003.
http://www.ijettjournal.org
Page 7
International Journal of Engineering Trends and Technology (IJETT) – Volume 26 Number 1- August 2015
Figure II
ISSN: 2231-5381
http://www.ijettjournal.org
Page 8