Visual Media Coding and Transmission

9.5 Conclusions

The capabilities of 3G networks and the suitability of different radio bearer configurations for supporting real-time video and voice communications were given in Section 9.2. A bearer configuration with a spreading factor of 8 is clearly unsuitable for video applications due to high channel-induced errors and high transmission-power requirements. The lower bound of E_b/N_o that could support acceptable video quality is found to be 8.5–10 dB for a spreading factor of 8 with a 1/3 rate convolutional code channel in vehicular and pedestrian environments. This is not achievable in a multi-user system, unless very sophisticated diversity techniques and interference-suppression techniques are employed. The minimum E_b/N_o requirement was reduced down to 6.3–8 dB for spreading factor 32 and 16 channels. Fast power control can lower the minimum E_b/N_o requirements further by 0.8–3 dB in tested operating environments. Perceptual quality measurements show that spreading factor 32 outperforms others for video transmission over similar operating conditions. However, this limits the operating source rate to 64 and 97 kbps with 1/3 and 1/2 rate channel coding, respectively. System-level performances demonstrate the necessity of advanced antenna techniques, adaptive resource allocation, and combined source-and channel-quality enhancement techniques in achieving 95% user satisfaction for real-time video services even for source rates as low as 64 kbps.

In addition to the investigation ...