Turbo Diversity S heme applied to JPEG Image

Turbo Diversity S heme applied to JPEG Image Transmission Wei Xiang Institute for Tele ommuni ations Resear h University of South Australia Mawson Lakes Blvd Mawson Lakes SA 5095 Australia e-mail: wei spri.levels.unisa.edu.au S. Adrian Barbules u Institute for Tele ommuni ation Resear h University of South Australia Mawson Lakes Blvd Mawson Lakes SA 5095 Australia Abstra t | A novel turbo diversity s heme (TDS) applied to JPEG oded image is proposed in this paper. By utilising the built-in turbo enoder stru ture, the transmitted JPEG image enoded by a rate half ode is re overed at the reeiver using a more powerful rate third ode generated by the proposed TDS. Simulation results reveals the TDS obtains a signi ant oding gain over onventional diversity s hemes in terms of both obje tive and subje tive measurements. I. Introdu tion Visual signals su h as ompressed still images are very vulnerable to hannel noise. Usually, hannel oding is utilised to prote t the transmitted visual signals. The Joint Photograph Experts Group (JPEG) standard [1℄ proposed in 1992 is widely used for still image ompression and transmission. Turbo odes [2℄ are suitable for prote ting multimedia signals su h as images sin e these visual signals are hara terised by a large amount of data, even after ompression. In this paper, we address the issue of JPEG oded image transmission over both additive white Gaussian noise (AWGN) and Rayleigh fading hannels, in whi h turbo odes are used for hannel oding. We onsider a s enario where a re eiver re eives the same JPEG image via two independent noisy hannels, i.e., AWGN or Rayleigh fading hannels. A turbo diversity s heme (TDS) is proposed to improve the transmitted image quality over su h two noisy hannels. The advantage of TDS is that the rate half turbo odes used by ea h transmitter an be ombined into a powerful rate third turbo ode at the re eiver by utilising the built-in stru ture of the turbo en oder. II. System Model We onsider a s enario where a user re eives the same information via two independent noisy hannels. Both AWGN and Rayleigh fading hannels are studied. Figure 1 illustrates the blo k diagram of the ommuni ation system studied in this work. JPEG standard is used as the sour e oding te hnique, while turbo odes are used as the hannel error prote tion s heme. We onsider two transmitter and re eiver pairs and two independent noisy hannels. The hannel model is shown in Figure 2. The Rayleigh fading hannels are assumed to be at whi h means the symbol rate is mu h lower JPEG Encoder Turbo Encoder QPSK Modulator