Wavelet Video Coding for Satellite Transmission Reliability
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Solution Overview
Problem
Conventional video coders are ineffective in transmitting digital imagery and real-time video over low-bit-rate wireless links due to limited channel bandwidth, high probability of error from latency and fading effects, and channel dropout in satellite-based communication networks.
Innovation Solution
A system and method utilizing a wavelet-based, multiple description video coding technique that splits video frames into quadtrees of transform coefficients, distributing them across multiple wireless channels for transmission, enabling error resilience and efficient bandwidth utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional video coders are used for transmission, then the transmission can be implemented with existing technology, but the transmission reliability deteriorates due to limited bandwidth, latency, fading effects, and channel dropout in satellite-based networks
Solution Approach 1:
The video signal is divided into multiple descriptions (first description and second description), where each description contains essential information for independent decoding. This segmentation allows the system to tolerate channel failures and packet loss in satellite-based networks, as each description can be decoded independently if received, thereby improving transmission reliability without requiring complex error correction mechanisms
Solution Approach 2:
The invention changes the coding parameters by using wavelet transform with quadtree structure to generate multiple descriptions at different bit rates. The first description contains high-frequency details while the second description contains low-frequency base information. This parameter transformation enables adaptive transmission where the receiver can reconstruct video quality based on available bandwidth and channel conditions, addressing the limited bandwidth issue in satellite networks
2Productivity
If multiple channels are used for transmission, then the bandwidth utilization improves, but the system complexity increases due to channel distribution and synchronization requirements
Solution Approach 1:
The coded video data is segmented into multiple packets distributed across different wireless channels. Each packet contains a portion of the first or second description. This segmentation enables parallel transmission over multiple channels, improving bandwidth utilization while maintaining manageable complexity through structured packetization and independent decodability of each description
Solution Approach 2:
The multiple description coding system provides universal functionality by enabling the same transmitted data to serve multiple purposes: full-quality reconstruction when all channels are available, and degraded-quality reconstruction when only some channels are available. This multi-functionality improves bandwidth utilization efficiency without requiring separate transmission systems for different channel conditions
3Reliability
If wavelet-based multiple description coding is implemented, then error resilience improves against packet loss and channel dropout, but the processing complexity increases
Solution Approach 1:
The wavelet transform and quadtree-based multiple description coding are performed in advance at the transmitter before transmission. This preliminary processing creates redundant descriptions that are inherently resilient to packet loss and channel dropout. The receiver simply needs to decode the received descriptions without complex error correction processing, shifting the processing complexity to the transmitter where it can be managed more effectively
Solution Approach 2:
The invention converts the harmful effect of channel dropout and packet loss into a beneficial feature by designing the multiple description coding such that lost descriptions can be compensated by using available descriptions. The wavelet structure allows graceful degradation where the loss of high-frequency details (first description) still permits reconstruction of the base image (second description), thereby converting potential errors into manageable quality variations
Data Source
AI summary
In a communication network (20), a video encoder/decoder system (114) and an encoding method (150) facilitate transmission of video frames (116) over multiple low-data-rate channels (46). Frame data (204) is generated for each video frame (116). The frame data (204) is transformed (172) to obtain transform coefficients (212), which are assembled (174) into quadtrees (216) and separately coded (178). In addition, motion vectors (166) are split into coding blocks (188) and separately coded (190). The quadtrees (126) and the motion vectors (166) are independently distributed among the multiple channels (46) for transmission. A decoding method (360) facilitates error resilient reception of transform coefficient packets (222) and motion vector packets (244) so that lost transform coefficients (374) and/or lost motion vectors (384) can be estimated at a receiving video encoder/decoder system (114) to reconstruct a received video frames 144.