OSVC_Meta-Data based Simulation Automation to overcome Verification Challenge...
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Reliable multimedia transmission under noisy condition
1. Salim Syed
FA12-BTN-032
Shahrukh Ali Khan
FA12-BTN-020
Department of Computer Science
COMSATS Institute of IT, Abbottabad
Supervised By:
Dr. Abbas Khalid
Reliable Multimedia Transmission under Noisy
conditions
2. β’ TURBO codes (are a class of high performance FEC ) are the channel
coding scheme used in wireless cellular networks as they are able
to reach the Shannon limit (maximum information transfer rate of
the channel , for a particular noise level ) . In our project we
introduce turbo codes, and implement a turbo encoder/decoder.
The decoding scheme employs the BCJR algorithm, the maximum
aposteriori algoithm (MAP). Also, one of the most important parts
is the analysis of the code; is the implementation of the EXIT chart
and BER analysis. On the basis of these implementations, we were
able to study the iterative behavior of turbo codes.
Introduction
3. β’ A random signal will be encoded via turbo encoder.
β’ The encoded data will be modulated and transmitted on the channel.
β’ The errors caused by the channel will be detected and corrected by the
decoder.
β’ The decoder will be implemented using maximum a-posteriori probability
(MAP) algorithms.
β’ To optimize the performance of the decoder, Exit chart and BER analysis
will be made.
β’ The practical demonstration will be shown by transferring random bits or
a multimedia file.
Scope
4. β’ Turbo codes are a class of high
performance forward error correction(FEC)
codes.
β’ Turbo codes on source side consist of two
convolutional code separated by an inter-leaver.
β’ On receiver side Turbo codes consist of Two
decoders, that work cooperatively in order to
refine and improve the estimate of the original
bits.
4
Turbo Codes
8. Exit chart example
β’ In the process to get the exit chart curve, the information bits are separated
into positive and negative values. Positive values are the values which are
greater then 0.5 and the negative values are lesser then 0.5.
β’ Positive values: 12.6774 2.1132 8.4528 -0.0145
β’ 1 2 3 4 5 6 7
β’ 0 1 0 1 1 0 1
β’ 0 12.6774 0 2.1132 8.4528 0 -0.0145
β’ The positive values are 1 and the negative values are 0
β’ Negative values : 1.9846 19.0188 -4.2264
β’ 1 2 3 4 5 6 7
β’ 0 1 0 1 1 0 1
1.9846 0 19.0188 0 0 -4.2264 0
9. Exit chart example
β’ To make a histogram we take the positive values from minimum to maximum
by giving the movement of 1
β’ -4.2264 -3.2264 -2.2264 -1.2264 -0.2264 0.7736 1.7736
β’ 2.7736 3.7736 4.7736 5.7736 6.7736 7.7736 8.773
9.7736 10.7736 11.7736 12.7736 13.7736 14.7736 15.7736
β’ 16.7736 17.7736 18.7736
β’ Here the oneβs are the point in the histogram where the positive values lies
β’ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
β’ 0 0 0 0 1 0 1 0 0 0 0 0 0 1 0 0 0
β’
β’ 18 19 20 21 22 23 24
β’ 1 0 0 0 0 0 0
10. Exit chart example
β’ These point which points the positive values on the histogram is divided
by it sum ( sum = 4 )
β’ 0 0 0 0 1/4 0 1/4 0 0 0 0 0 0 1/4 0 0 0 1/4 0 0 0
0 0
β’ Divide
β’ 0 0 0 0 0.2500 0 0.2500 0 0 0 0 0 0 0.2500 0 0
0 0.2500 0 0 0 0 0 0
11. Exit chart implementation
now to make a histogram for negative values we take the negative values from
mininum to maximum by giving the movement of 1
-4.2264 -3.2264 -2.2264 -1.2264 -0.2264 0.7736 1.7736
2.7736 3.7736 4.7736 5.7736 6.7736 7.7736 8.7736
9.7736 10.7736 11.7736 12.7736 13.7736 14.7736 15.7736
16.7736 17.7736 18.7736
These point ,points the negative values on the histogram is divided by it sum (
sum = 3 ). Here 2 show that 2 points are lies at the same location
1 2 3 4 5 6 7 8 9 10 11
2 0 1 0 0 0 0 0 0 0 0
12 13 14 15 16 17 18 19 20 21 22 23 24
0 0 0 0 0 0 0 0 0 0 0 0 0
31. Branch Matric()
Ο π
π
= π΄ π
π
. exp(β
π₯ πβπ’ π .2
2πΏ2 +
π¦ πβπ π
2πΏ2 )
Λj = 0, 1, 2, 3 (= # of states in the trellis).
Λk = 0, 1, 2, ..n (= # of information bits).
Λπ’ π = π π‘β transmitted information bit
Λπ π = π π‘β transmitted parity bit
Λπ₯ π = π π‘β received information bit
Λπ¦ π
= π π‘β
received parity bit
π΄ π
π
= a priori probability (i=0 if π’ π
is 0 and i=1 otherwise).
82. β’ An EXIT chart (Extrinsic information transfer
chart) is a tool to aid the construction of good
iteratively-decoded error-correcting codes
such as Turbo Codes.
β’ Exit Chart is one of the most important part is
the analysis of the code.
β’ Using the EXIT charts we will study the
behavior of our turbo codes.
82
EXIT Chart
84. Encoder Testing
Test Name Encoding
Test Date 08/3/2016
Application Name Reliable Multimedia Transmission under Noisy Conditions
Input Binary data of Image
Output Encoded Bits
Test Conductor Salim Syed and Sharukh Ali Khan
Verified By Dr.Abbas Khalid
85. Decoder Testing
Test Name Decoding
Test Date 26/3/2016
Application Name Reliable Multimedia Transmission under Noisy Conditions
Input Binary data of Image
Output Decoded Bits and Graph
Test Conductor Salim Syed and Sharukh Ali Khan
Verified By Dr.Abbas Khalid
86. Exit Chart Analysis
Test Name EXIT chart analysis
Test Date 15/4/2016
Application Name Reliable Multimedia Transmission under Noisy Conditions
Input System Generated Bits
Output Graph and Received Bits
Test Conductor Salim Syed and Sharukh Ali Khan
Verified By Dr.Abbas Khalid
87. BER Analysis
Test Name BER analysis
Test Date 22/4/2016
Application Name Reliable Multimedia Transmission under Noisy Conditions
Input Image file
Output Graph and Received image file
Test Conductor Salim Syed and Sharukh Ali Khan
Verified By Dr.Abbas Khalid