Joint Source-Channel Coding of Images Toolbox

Simulation of transmission of SPIHT encoded images over unreliable channels. Requires the MATLAB Communications Toolbox. Scripts for measuring the channel error rate, RCPC code characteristics and Rate-Distortion (R-D) curve of the SPIHT compression for the input image and selected channel characteristics.

Functions

• awgn_EsN0 - Simulation of the Additive White Gaussian Noise (AWGN) channel
• BSC_BER - Simulation of the Binary Symemtric Channel (BSC)
• GE_awgn - Simulation of the Gilbert-Elliot (GE) channel, using two AWGN channels
• get_channel - Loads a predefined channel (saved in a txt file)
• get_RCPC_code - Loads a predefined RCPC code from a default code family ('Punct_codes.txt')
• RCPC_encode - Rate Compatible Punctured Convolutional (RCPC) coding of the binary stream
• RCPC_test_equal_data - Transmission of packets with constant data part, using RCPC
• RCPC_test_equal_packet - Transmission of packets with constant size, using RCPC
• optimal_RCPC_equal - Computes the Equal Error Protection (EEP) scheme for a given image and channel
• send_image_equal - Transmission of SPIHT encoded image using EEP
• send_image_equal_RS - Transmission of SPIHT encoded image using EEP and Reed-Solomon protection
• optimal_RCPC_unequal - Computes the Unequal Error Protection (UEP) scheme for a given image and channel
• send_image_unequal - Transmission of SPIHT encoded image using UEP
• script_channel_performance - Measures the BER and PER values for RCPC transmission on a given channel
• RDcurveBytePrec - Runs SPIHT over range of target bitrates and stores the R-D curve

Examples

get_channel (contents of the file AWGN1.txt):

ch_handle=@awgn_EsN0;
parametar.EsN0=-0.8556;
parametar.state=-1;
parametar.Bch=128000;
parametar.Nch=256;

get_RCPC_code (one RCPC entry from the file Punct_codes.txt):

8/9
[Hag88]
Memory=6
CodeGenerator=[133 171 145]
PunctCode=f78800
cd=[0,0,24,740,13321,217761,3315491,48278177]
%Punctcode=[f7,88,00]=[1 1 1 1 0 1 1 1,1 0 0 0 1 0 0 0,0 0 0 0 0 0 0 0]

RCPC_encode:

>> signal=round(rand(1,8))
 signal =
      0     1     1     0     0     0     1     0
>> [Memory,Ib,Kb,t,PN,P,TotRate,PunctInd] = get_RCPC_code('8/9');
>> outsignal = RCPC_encode(signal,Memory,t,P,PunctInd)
 outsignal =
      1     1    -1    -1    -1     1    -1     1     1

RCPC_test_equal_data:

>> [diffvec,BER,PER]=RCPC_test_equal_data(100,128,'AWGN1','1/2',8,0);
 Mother code rate: 1/3
 Puncturing code rate: 16/24
 Total rate: 1/2
 Packet size: 284
 Number of packets: 100
 Transmitted data bits: 12800

 ***Errors Statistics***
 Errors = 52
 BER = 0.004063
 Packet errors = 12
 PER = 0.120000
 (CRC) Correctly detected packet errors = 12
 (CRC) Detected packet errors = 12

script_channel_performance:

>> script_channel_performance(@RCPC_test_equal_packet,100000,16,'GE1');   

optimal_RCPC_equal:

>> optimal_RCPC_equal(1000,16,'GE1','Lena512RD','draw_small');
RCPC total rate: 1/1 - average PSNR: 17.281731
RCPC total rate: 8/9 - average PSNR: 18.406105
RCPC total rate: 4/5 - average PSNR: 18.432578
RCPC total rate: 2/3 - average PSNR: 19.129653
RCPC total rate: 4/7 - average PSNR: 21.051831
RCPC total rate: 1/2 - average PSNR: 24.052347
RCPC total rate: 4/9 - average PSNR: 26.976499
RCPC total rate: 2/5 - average PSNR: 29.522427
RCPC total rate: 4/11 - average PSNR: 30.491567
RCPC total rate: 1/3 - average PSNR: 30.432119
***
Minimal distortion RCPC code: 4/11
PSNR: 30.491567