Video Encoder Error Control via MAC Layer NAK Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing video transmission systems over wireless channels face challenges in promptly addressing and controlling errors on the reverse link, leading to potential degradation in video quality due to delayed feedback from receiving devices.
Innovation Solution
The implementation of a method where a video encoder receives negative acknowledgement (NAK) information from the medium access control (MAC) layer to determine lost video packets and perform error control measures, such as inserting intra-frames or adjusting macroblock refresh rates, without relying on end-to-end feedback, thereby minimizing error propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If end-to-end feedback is used for error detection, then error control can be performed, but the feedback delay degrades video quality
Solution Approach 1:
The patent introduces the MAC layer as an intermediary that performs error detection on video packets before they reach the application layer. The MAC layer uses NAK (negative acknowledgement) signals to indicate lost packets to the video encoder, enabling immediate error control without waiting for end-to-end feedback from the receiving device. This mediator approach resolves the contradiction by providing timely error information while maintaining the benefits of end-to-end error control.
2Reliability
If real-time error control is implemented using MAC layer NAK information, then video quality is maintained, but the system complexity increases
Solution Approach 1:
The patent leverages the existing MAC layer, which is already part of the wireless communication infrastructure, to perform dual functions: traditional MAC operations and video error detection. By reusing the MAC layer's NAK mechanism (originally designed for general packet error control) for video-specific error control, the system achieves real-time video quality maintenance without adding entirely new complexity. The video encoder integrates NAK information processing into its existing packet handling routines.
3Reliability
If error control measures such as intra-frames are inserted frequently, then error propagation is minimized, but bandwidth consumption increases
Solution Approach 1:
The patent implements dynamic error control where the video encoder adjusts the frequency and type of error control measures based on real-time NAK information from the MAC layer. Instead of frequently inserting intra-frames regardless of conditions, the system responds adaptively: inserting intra-frames or adjusting macroblock refresh rates only when NAK signals indicate actual packet loss. This dynamic approach minimizes error propagation while optimizing bandwidth usage by avoiding unnecessary control measures during error-free transmission periods.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The disclosure relates to reverse link lower layer assisted video error control. A method may encode video data, form a packet with the encoded video data, and transmit the packet across a wireless channel to an access network. A medium access control (MAC) layer may receive a negative acknowledgement (NAK) from the access network. The method may determine whether the received NAK is associated with a packet that contains video data. If the received NAK is associated with a packet that contains video data, the method may perform error control.