MAC Layer ACK Buffering for Wireless Throughput
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Solution Overview
Problem
The frequent operation of congestion control mechanisms in wireless communication systems due to burst errors in wireless links leads to increased packet retransmissions, degrading system throughput, as existing solutions like indirect TCP and snooping agent TCP are complex and inefficient.
Innovation Solution
A transport control method that involves a MAC layer controlling ACK transport in response to a TCP segment, temporarily storing ACK segments, detecting an average transmission rate, and resetting the RTO timer to reduce unnecessary retransmissions and maintain system throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If congestion control mechanism operates frequently due to burst errors in wireless link, then reliability of data transmission is improved, but system throughput deteriorates due to increased packet retransmissions
Solution Approach 1:
The patent introduces an intermediary mechanism at the MAC layer that buffers and manages ACK packets before they reach the TCP layer. This intermediary buffers ACK packets during burst error periods, preventing them from triggering unnecessary TCP retransmissions while still maintaining reliable delivery through controlled delivery to the transport layer
Solution Approach 2:
The patent segments the acknowledgment process into two distinct phases: MAC layer buffering and management of ACK packets, followed by controlled delivery to the TCP layer. This segmentation allows the wireless-specific ACK management to be separated from the end-to-end TCP reliability mechanism, enabling independent optimization of each layer
2Productivity
If indirect TCP mechanism is used to separate flow and congestion control functions, then system throughput is improved, but end-to-end connection guarantee deteriorates
Solution Approach 1:
The patent merges the advantages of both direct and indirect TCP approaches by implementing MAC layer ACK buffering (similar to indirect TCP) while maintaining TCP's end-to-end connection guarantee. The combination allows throughput improvement through separated control functions while preserving the reliability guarantee through maintained TCP oversight
3Reliability
If snooping agent TCP mechanism is deployed to realize TCP in wireless link, then reliability of data transmission is improved, but device complexity increases due to required TCP stacks and memory at remote node
Solution Approach 1:
The patent extracts the complex TCP stack and segment buffering requirements from the remote wireless node and relocates them to the base station's MAC layer. This extraction allows the remote terminal to maintain simple TCP implementation while still benefiting from enhanced reliability through the base station's ACK management capabilities
Data Source
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AI summary
A transport control method in a transmitter of a wireless communication system, which includes a transport layer having a congestion control function of transmitting data in a segment basis and retransmitting a segment if an RTO timer expires before receipt of an ACK segment is received in response to transmission of the segment and a MAC layer for detecting receipt of an ACK segment through a wireless link and transporting the detected ACK segment to the transport layer, includes temporarily storing received ACK segments in the MAC layer; detecting an average transmission rate of data segments; and transporting the stored ACK segments to the transport layer at the average transmission rate. Accordingly, by controlling an upward transport rate of a received ACK message by referring to an RTO value of a TCP in a MAC layer, unnecessary retransmission can be prevented by a congestion control function.