Performance of JPEG Image Transmission Using Proposed Asymmetric Turbo Code
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Research Article Performance of JPEG Image Transmission Using Proposed Asymmetric Turbo Code K. Ramasamy,1 Mohammad Umar Siddiqi,2 and Mohamad Yusoff Alias1 1 Faculty 2 Faculty
of Engineering, Multimedia University, Cyberjaya 63100, Selangor, Malaysia of Engineering, International Islamic University Malaysia, P.O. Box 10, Kuala Lumpur 50728, Malaysia
Received 23 February 2006; Revised 26 October 2006; Accepted 1 November 2006 Recommended by Richard J. Barton This paper gives the results of a simulation study on the performance of JPEG image transmission over AWGN and Rayleigh fading channels using typical and proposed asymmetric turbo codes for error control coding. The baseline JPEG algorithm is used to compress a QCIF (176 × 144) “Suzie” image. The recursive systematic convolutional (RSC) encoder with generator polynomials (1, D3 + D2 + 1/D3 + D + 1), that is, (13/11) in decimal, and 3G interleaver are used for the typical WCDMA and CDMA2000 turbo codes. The proposed asymmetric turbo code uses generator polynomials (1, D3 + D2 + 1/D3 + D + 1; D3 + D2 + 1/D3 + 1), that is, (13/11; 13/9) in decimal, and a code-matched interleaver. The effect of interleaver in the proposed asymmetric turbo code is studied using weight distribution and simulation. The simulation results and performance bound for proposed asymmetric turbo code for the frame length N = 400, code rate r = 1/3 with Log-MAP decoder over AWGN channel are compared with the typical system. From the simulation results, it is observed that the image transmission using proposed asymmetric turbo code performs better than that with the typical system. Copyright © 2007 Hindawi Publishing Corporation. All rights reserved.
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INTRODUCTION
The constraints on bandwidth, power, and time in many image communication systems prohibit transmission of uncompressed raw image data. Compressed image representation, however, is very sensitive to bit errors, which can severely degrade the quality of the image at the receiver. A wireless channel generally suffers from severe effect of multipath propagation caused by the diffractions, reflections, and scattering from obstacles such as buildings, furniture, or moving objects. The transmitted signal arrives at the receiver from different paths, with each path introducing a time-varying attenuation and a time delay. The result is a set of replicas of the transmitted signal arriving at the receiver with time-varying amplitudes and phase shifts. Possible shadowing of the line-of-sight path by obstacles causes further variation of the received signal strength. The above problems make the channel a long burst-error channel. Thus, some error control strategy is needed to transmit highly compressed images reliably over such a burst-error channel to combat the effect of fading. Turbo codes have attracted attention since introduced in 1993 [1]. Since turbo codes are a parallel concatenation of two or more convolutional codes separated by pseudo-
random interleaver, the characteristic of both constituent encoder as well as the interleaver is
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