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Power-Rate Distortion Analysis for Wireless Video

consumption model control encoding

Definition: Power-rate distortion analysis is important for wireless video communication applications in energy management, resource allocation, and QoS provisioning, especially over wireless video sensor networks.

To design an energy-scalable standard video encoder, we take three major steps:

Step 1) We group the encoding operations into several modules, such as motion prediction, pre-coding (transform and quantization), and entropy coding, and then introduce a set of control parameters G = [ ? 1 , ? 2 ,? L ] to control the power consumption of each module. The encoding power consumption, denoted by P, is then a function of G, denoted by P ( ? 1 , ? 2, ? L ). The expression of this function also depends on the power consumption model of the specific micro-processor.

Step 2) We analyze the rate-distortion behavior of each control parameter, and integrate these models into a comprehensive parametric rate-distortion model for the video encoder, denoted by D ( R ; ? 1 , ? 2 ,? L ).

Step 3) We perform optimum configuration of the power control parameters to maximize the video quality (or minimize the video distortion) under the power constraint. This optimization problem can be mathematically formulated as follows:

where P is the available power consumption for video encoding. The optimum solution, denoted by D(R;P) , describes the P-R-D behavior of the video encoder. To view the P-R-D model in more detail, we plot the D-P curves for different bit rates, ranging from 0.01 bpp to 1.0 bpp in Fig.l-(a). Fig.l-{b) shows the D-P curves at different bit rates R s , and Fig.l-© shows the D-R curves at different power consumption levels P s (in percentages of the maximum power consumption level). We can see that when the power supply level is low, the function is almost flat, which means the video processing and encoding efficiency is very low; hence, in this case, more bandwidth does not improve the video presentation quality. The P-R-D model has direct applications in energy management, resource allocation, and QoS provisioning in wireless video communication, especially over wireless video sensor networks. For detailed energy-scalable encoder design and P-R-D analysis, please refer to.

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