Unequal error protection for OFDM systems in time-varying channels

Time-varying channel causes intercarrier interference (ICI) and impairs the orthogonality among subcarriers in wireless mobile Orthogonal Frequency Division Multiplexing (OFDM) systems. The ICI and loss of carrier orthogonality degrade the bit error rate (BER), and thus results in intolerable loss of quality especially in applying multimedia data transmission. In this paper, we propose an unequal density of pilot placement for OFDM systems in time-varying channel, which provides Unequal Error Protection (UEP) for important multimedia transmission. A dynamic image data assignment (DIDA) scheme for UEP utilizing visual saliency is presented to reallocate image data in OFDM symbol for the UEP transmission. Simulation results show substantial improvements of quality in the region of interest in the image by using proposed method.