Adaptive Gain for LEDBAT Background Connections
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Solution Overview
Problem
The Low Extra Delay Background Transport (LEDBAT) protocol faces issues such as reliance on one-way measurements, latecomer advantage, unfairness between connections, and latency drift, leading to saturated connections and unnecessary slowdowns, which affect user experience and network performance.
Innovation Solution
The introduction of an adaptive congestion window gain for background connections, dynamically adjusted based on round trip time, along with modified slow start and periodic slowdowns, addresses these issues by optimizing communication rates and ensuring fair resource sharing among connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the LEDBAT protocol uses fixed gain values for background connections, then implementation is simple, but latency drift and unnecessary slowdowns occur
Solution Approach 1:
The patent applies dynamics by making the gain value adaptive rather than fixed. The gain is dynamically adjusted based on round trip time measurements, allowing the background connection to respond to changing network conditions. This resolves the contradiction by accepting increased implementation complexity to achieve reliable connection stability without latency drift or unnecessary slowdowns.
2Difficulty of detecting and measuring
If the LEDBAT protocol uses one-way delay measurements, then measurement is simple, but latecomer advantage and unfairness between connections occur
Solution Approach 1:
The patent implements feedback by using round trip time measurements where acknowledgment packets provide information about network conditions back to the sender. This two-way measurement mechanism eliminates the latecomer advantage and ensures fairness between connections by providing accurate feedback about actual network state, resolving the contradiction between measurement simplicity and fairness.
3Productivity
If background connections use aggressive transmission rates, then data transfer speed is high, but user experience deteriorates due to network saturation
Solution Approach 1:
The patent changes the parameter of transmission rate by introducing adaptive gain control based on round trip time. The background connection dynamically adjusts its transmission rate parameter to maintain high productivity when network conditions permit while preventing harmful saturation effects that degrade user experience, resolving the contradiction between data transfer rate and impact on user experience.
Data Source
AI summary
The technologies disclosed herein provide improvements to the Low Extra Delay Background Transport (LEDBAT) protocol. Some aspects of the present disclosure introduce an adaptive congestion window gain for background connections. In some configurations, a gain value for influencing the transmission rate of a background connection is dynamically adjusted based on data indicating a round trip time (RTT). The RTT includes a sum of a time in which the data is communicated to a remote device and a time in which acknowledgement is data returned from the remote device. In some configurations, the gain is decreased when the RTT is below a threshold and the gain is increased when the RTT is above the threshold. Among other features, the present disclosure also provides techniques involving a modified slow-start, multiplicative decrease and periodic slowdowns. The features disclosed herein mitigate some existing issues, such as latency drift, inter-LEDBAT fairness, and unnecessary slowdowns.