Visual Media Coding and Transmission

9.2 Link-level Quality Adaptation Techniques

(Portion reprinted, with permission, from C. Kodikara, S.T. Worrall, A.M. Kondoz, “Energy efficient video telephony over UMTS”, IEEE VTC-Spring 2004, 17–19 May 2004, Milan, Italy. ©2004 IEEE.)

Efficient transmission power utilization is an important design criterion in interference-limited cellular systems, such as UMTS networks. System capacity is limited by the total interference experienced within the cell coverage. Thus, the optimization of power consumption for an individual user can provide an increase in system capacity, as well as in the QoS experienced by the user.

Recently, several energy minimization techniques for wireless video applications have been proposed [17, 18]. All of these techniques are optimized to achieve a target video quality while minimizing the transmission power. In [18], joint error resilience and transmission power management at video frame level is proposed. However, as the video frame quality is variable in nature (even in an error-free environment), controlling the transmission power to achieve a target frame quality at the video frame level is inaccurate and would result in poor system performance. This problem can be solved by minimizing the total consumed power within a certain period, while achieving the optimal average video quality. The method proposed in [18] employs this concept for intra-refreshed video sequences, thus video performance is optimized for a fixed intra-refresh period. However, ...