TCP Transmission Rate Adjustment in Mobile Ad Hoc Networks
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Solution Overview
Problem
Conventional TCP congestion control methods in ad hoc networks lead to inefficient use of network resources due to abrupt transmission rate adjustments, excessive load on the network, and high packet loss, especially in mobile ad hoc environments where data availability varies significantly.
Innovation Solution
A method for adjusting the transmission rate in TCP by calculating a difference between current and previous transmission rates, setting upper and lower thresholds based on standard variation, and updating the congestion window to optimize transmission rates, thereby reducing network load and packet loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional TCP congestion control uses simple exponential increase of transmission rate, then the transmission rate increases quickly, but abrupt congestion is generated and network efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the transmission rate adjustment adaptive rather than fixed. The congestion window (cwnd) is dynamically adjusted based on real-time network conditions including RTT variations and bandwidth availability. The system transitions from static exponential increase to dynamic adjustment that responds to changing network states, resolving the contradiction between quick rate increase and avoiding abrupt congestion.
Solution Approach 2:
The patent implements feedback mechanisms by continuously monitoring network parameters such as RTT (Round Trip Time) and bandwidth availability. The transmission rate adjustment is based on feedback from these measurements, allowing the system to adapt to actual network conditions. This feedback loop prevents abrupt congestion by adjusting the rate based on real-time network response rather than following a fixed exponential pattern.
2Reliability
If conventional TCP congestion control reduces transmission rate by half in congestion state, then congestion is relieved, but network resources are not efficiently utilized
Solution Approach 1:
The patent applies parameter changes by modifying the congestion window (cwnd) adjustment strategy. Instead of the fixed halving rule, the system adjusts cwnd based on calculated bandwidth availability and RTT variations. The patent introduces new parameters such as base bandwidth (base_bw) and current bandwidth (cur_bw) to guide more nuanced adjustments, allowing the system to maintain higher transmission rates when network conditions permit, thus improving resource utilization while still controlling congestion.
Solution Approach 2:
The patent makes the congestion response dynamic by adjusting the transmission rate based on real-time network conditions rather than applying a fixed halving rule. The system continuously monitors bandwidth availability and RTT, then adaptively adjusts cwnd accordingly. This dynamic approach allows the system to relieve congestion when necessary while maximizing resource utilization when the network can handle higher rates.
3Productivity
If transmission rate is increased to maximize link utilization, then throughput improves, but packet loss increases due to collisions in wireless environment
Solution Approach 1:
The patent applies partial action by adjusting the congestion window (cwnd) based on calculated bandwidth availability rather than maximizing it completely. The system calculates base bandwidth and current bandwidth, then adjusts cwnd to a level that is sufficient to achieve good throughput but not so high as to cause excessive collisions and packet loss. This partial adjustment strategy balances throughput improvement with packet loss prevention in the wireless environment.
4Reliability
If ACK-response packets are transmitted to confirm receipt, then transmission reliability improves, but network load increases due to additional traffic
Solution Approach 1:
The patent applies merging by combining the congestion control function with the existing ACK mechanism. Rather than introducing separate congestion control packets, the system utilizes the existing ACK-response packets for dual purposes: confirming receipt and providing congestion control feedback. This integration reduces additional network traffic while maintaining both transmission reliability and congestion control functionality.
Data Source
AI summary
A method for adjusting a transmission rate in the transmission control protocol (TCP) under a mobile ad hoc network environment, including calculating a difference value (Diff) between the current transmission rate (cur_bw) and the previous transmission rate (base_bw), setting up upper and lower thresholds by calculating the standard variation (basebw_var) of the previous transmission rate, and updating the previous transmission rate to the current transmission rate depending upon a comparison result of Diff and the size of the upper and lower thresholds.