Fragmented Packet Retransmission Credit Allocation
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Solution Overview
Problem
Existing methods for retransmitting fragmented packets in communication networks with wireless links are sensitive to channel disturbances and provide unequal error protection, leading to inefficient packet transmission and high error rates due to the assumption of correct acknowledgments and global retransmission credits.
Innovation Solution
Assigning a transmission persistence to each fragmented packet, with the sum of persistences equal to a predetermined overall cost, and dynamically reallocating retransmission credits based on acknowledgment receipt, allowing for unequal error protection and improved error probability distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a global retransmission credit is assigned to all fragments of an IP packet, then the transmission delay is controlled, but the system becomes highly sensitive to channel disturbances and generates unequal error protection
Solution Approach 1:
The global retransmission credit is segmented into individual per-fragment credits. Each fragment receives its own credit allocation rather than sharing a common pool, which isolates the retransmission reliability of each fragment from channel disturbances affecting others and eliminates the unequal error protection problem.
Solution Approach 2:
Each fragment is assigned differentiated retransmission credits based on its specific requirements and position in the packet sequence. This local customization of credit allocation allows optimal error protection for each fragment while maintaining overall transmission delay control through coordinated management.
2Device complexity
If a global retransmission credit is assigned to all fragments, then resource allocation is simplified, but unequal error protection is generated where the first fragment has much lower error probability than subsequent fragments
Solution Approach 1:
The unified credit management system is segmented into independent per-fragment credit managers. Each fragment has its own credit counter and retransmission logic, which simplifies the control logic for each fragment while achieving uniform error protection across all fragments through individualized credit allocation.
Solution Approach 2:
The retransmission credit parameter is changed from a global shared value to individual per-fragment values. This parameter transformation enables differentiated error protection strategies for each fragment while maintaining manageable complexity through standardized per-fragment processing routines.
3Device complexity
If the retransmission method assumes correct reception of acknowledgments, then the protocol is simplified, but performance degrades when the propagation channel is disturbed
Solution Approach 1:
The system performs preliminary validation of acknowledgment packets before processing them. By checking acknowledgment integrity in advance and having fallback mechanisms prepared, the system maintains simplified protocol operation under normal conditions while being robust against channel disturbances that corrupt acknowledgments.
Solution Approach 2:
The protocol incorporates cushioning mechanisms such as acknowledgment timeout counters and retransmission of control packets. These preparatory measures protect against acknowledgment loss or corruption without requiring complex real-time response mechanisms, maintaining protocol simplicity while improving reliability in disturbed channels.
Data Source
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AI summary
The invention relates to a method for retransmitting fragmented packets in which retransmission credit is transferred from one fragment to the next. The invention overcomes the drawbacks of existing methods by significantly improving performance in terms of packet loss rates and by allowing the configuration of the error probability distribution of fragments within an IP packet.