Optimal rate allocation and security schemes for image and video transmission over wireless channels

In this dissertation, we study several issues for image and video coding and transmission over wireless networks which include optimal source and channel rate allocation, error resilient video coding, and key distribution schemes for secure multimedia multicast.; We propose a progressive image transmission scheme in the case of transmission over broadband wireless channels using multiple antennas and orthogonal frequency division multiplexing (OFDM). By employing multiple antennas and OFDM, we transfer the frequency selective, time varying fading channels to parallel Gaussian noisy channels when the number of antennas is large enough, as a result, the forward error control (FEC) coding can be more effective and the source throughput is increased.; We propose an integrated framework of optimal rate allocation for video coding in the case of transmission over wireless channels without feedback channel available. For a fixed channel bit rate and finite number of channel coding rate, the proposed scheme can find out the optimal source and channel coding pair and corresponding robust video coding scheme such that the expected end-to-end distortion of video signals can be minimized. With the assumption that encoder has the stochastic information of the channel model, the proposed scheme takes into account video coding, channel coding and packetization, error concealment techniques altogether.; We also propose a novel data embedding scheme for fractional-pixel based video coding algorithms such as H.263 and MPEG-2. By modifying the motion estimation procedure at fractional-pel precision, two bits data can be embedded in a motion vector for a Inter-mode coded macroblock. As an application example of the proposed data embedding scheme, an error-resilient video coding scheme is also presented. The proposed scheme has better error recovery performance than previous methods because of this embedded coding scheme.; Another important problem considered in this dissertation is security for multimedia multicast such as video conferencing and pay-per-view. We propose a new key management scheme for the distribution of multicast rekeying message. Furthermore, we present a new key distribution scheme for multimedia multicast by exploiting the characteristics of multimedia signals such that key updating messages can be hidden in the data and used in conjunction with encryption to protect the multimedia data from unauthorized access.