Video Performance Requirements

While requirements for the voice service have been studied extensively in the literature and can be rather clearly defined, the corresponding requirements for the video telephony performance are much more open for implementation.

For voice it is sufficient to provide data rates of slightly above 10 kbps for good speech quality. For video the required data rates are much higher. The exact data rates depend strongly on the video size, but for current mobile screens a good quality video requires data rates of 64-128 kbps. Providing such data rates consistently also at the cell border is more problematic, especially in networks which have been deployed for voice coverage. Due to limited availability of sufficient data rate, most used codecs can adjust their data rate to the current conditions.

As the frame rate of typical mobile video codecs is smaller than 50 Hz, the video is not as sensitive to jitter as voice. The lower the frame rate, the less impact the jitter has on delay.

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