Packet Transmission Redundancy Control for Deadline-Limited Delivery
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Solution Overview
Problem
Current packet transmission techniques, such as RTP and TCP, face challenges in ensuring reliable delivery of multimedia data over best-effort networks, particularly due to high error rates in wireless environments and insufficient reliability in stream transmission systems, where packet loss or delay can lead to incomplete or delayed playout, and existing error correction methods like ARQ and FEC either fail to meet delay constraints or increase network congestion.
Innovation Solution
A transmission technique that combines automatic retransmission (ARQ) and forward error correction (FEC) systems, dynamically determining redundancy based on network state information to maintain an allowable loss rate after error correction, optimizing redundancy to avoid unnecessary network congestion and data reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ARQ system is used for retransmission of lost packets, then reliability is improved, but delay increases and network congestion occurs
Solution Approach 1:
The patent dynamically adjusts the retransmission strategy based on network conditions and packet characteristics. The transmission apparatus determines whether to use ARQ retransmission or FEC recovery adaptively, changing the error correction method according to real-time network state, packet type, and delay constraints to optimize both reliability and delay performance
Solution Approach 2:
The patent segments error correction into two distinct mechanisms: ARQ for packets without strict delay constraints and FEC for packets with tight deadlines. By dividing the error correction task into these two segments with different strategies, the system achieves reliable delivery for non-time-critical packets while ensuring timely delivery for time-sensitive packets
2Reliability
If FEC system is used for error correction, then reliability is improved, but transmission overhead increases
Solution Approach 1:
The patent dynamically determines the FEC block size and redundancy level based on network conditions, packet loss rate, and delay constraints. Rather than using fixed FEC parameters, the system adapts the amount of redundant data generated to match actual network requirements, reducing unnecessary overhead while maintaining sufficient error correction capability
Solution Approach 2:
The patent applies different error correction strategies to different packets based on their specific characteristics. Time-sensitive packets receive FEC protection with appropriate redundancy levels, while non-time-critical packets use ARQ. This localized application of error correction methods optimizes the balance between reliability and transmission overhead for each packet type
3Reliability
If TCP system is used for data transmission, then reliability is improved, but throughput decreases and delay increases
Solution Approach 1:
Instead of using TCP's acknowledgment-based retransmission mechanism which causes head-of-line blocking and reduces throughput, the patent inverts the approach by using UDP with selective ARQ and FEC. This allows out-of-order packet delivery to proceed while missing packets are recovered independently, maintaining high throughput while achieving reliable delivery
Solution Approach 2:
The patent segments the reliability mechanism from the transport protocol, applying error correction (ARQ and FEC) at the application layer rather than relying on TCP's transport-layer reliability. This segmentation allows the use of lightweight UDP for high-speed data transmission while adding selective error correction only where needed, avoiding TCP's overhead and throughput limitations
Data Source
AI summary
A packet transmission apparatus is provided. The packet transmission apparatus transmits a packet having a limited arrival deadline through a best-effort network. The packet transmission apparatus includes an automatic packet retransmission section to control retransmission of an undelivered packet, a forward error correction coding section to add a redundant packet to a data packet block, and a redundancy determining section to dynamically determine redundancy of the redundant packet based on observed network state information, so that a loss rate after error correction at a receiver achieved by only the retransmission of the undelivered packet satisfies an allowable loss rate after error correction.