Link-Layer TCP Throughput Optimization via Cross-Layer Dynamics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
TCP throughput is impaired in wireless networks due to congestion control mechanisms invoked in response to wireless channel losses, and existing solutions either require modifications to TCP, increase processing overhead, or fail to adapt to instantaneous wireless dynamics.
Innovation Solution
A method and system that utilize link-layer adaptation mechanisms, such as adaptive modulation and coding, to optimize TCP throughput by modeling congestion window size variation patterns and selecting appropriate transmission modes based on instantaneous TCP flow dynamics using a dynamic programming framework.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TCP congestion control mechanisms are invoked in response to wireless channel losses, then TCP semantics are preserved, but data transfer rate is reduced and end-to-end throughput is impaired
Solution Approach 1:
The patent introduces an intermediary mechanism at the link layer that sits between the physical wireless channel and the TCP protocol. This intermediary monitors wireless channel conditions and selectively protects TCP segments based on channel quality, preventing unnecessary invocation of TCP congestion control while preserving TCP semantics. The link layer acts as a mediator that absorbs the impact of wireless losses before they reach TCP.
2Productivity
If end-to-end schemes like ELN are implemented to distinguish congestion from wireless losses, then TCP throughput is improved, but TCP implementation must be modified
Solution Approach 1:
Instead of modifying TCP to add ELN options and congestion distinction logic, the patent places an intermediary link layer protocol that handles wireless loss protection. This keeps TCP implementation unchanged while achieving the same throughput improvement goal, reversing the usual approach of modifying end-to-end protocols rather than introducing link layer intermediaries.
3Reliability
If link-layer adaptation measures like adaptive modulation and coding are used, then transmission reliability is improved, but rate and delay variability increases
Solution Approach 1:
The patent implements dynamic link-layer adaptation where modulation and coding schemes are adjusted in real-time based on instantaneous wireless channel conditions and TCP flow dynamics. The system monitors channel quality metrics and TCP congestion window variations to dynamically select optimal transmission modes, balancing reliability improvement against rate variability. This dynamic approach allows the system to adapt to changing conditions rather than using fixed adaptation rules.
Solution Approach 2:
The system changes transmission parameters (modulation order, coding rate, transmission power) based on monitored channel conditions and TCP flow state. By adjusting these parameters dynamically according to real-time measurements, the system optimizes the trade-off between transmission reliability and rate variability, preventing excessive conservatism that would cause unnecessary rate fluctuations.
4Productivity
If TCP aware link layer protocols are implemented to shield TCP from wireless losses, then processing overhead increases, but TCP throughput is improved
Solution Approach 1:
The patent applies local quality protection selectively to specific TCP segments based on their position in the transmission flow and current channel conditions. Rather than uniformly protecting all segments with complex TCP-aware protocols, the system identifies critical segments that need protection and applies link-layer redundancy only to those, reducing overall processing overhead while maintaining throughput benefits.
Data Source
AI summary
A method and a system is provided for optimizing the throughput of a TCP flow from a TCP source to a TCP destination in a wireless network with the path of the flow encompassing a wireless link between a wireless transmitter and a wireless receiver. The throughput is optimized by using link-layer mechanisms at the wireless transmitter which are adaptive to the instantaneous TCP dynamics of the TCP flow. In particular, a cross-layer approach is disclosed which serves to tunnel information of TCP congestion control dynamics directly from the TCP based transport layer to the data link-layer which selects in response to these information modulation and/or coding schemas to transmit TCP segments via data link-layer blocks with improved TCP throughput.