Transmission Rate Control for Rapid Bandwidth Adaptation
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Solution Overview
Problem
In video conference systems using best effort networks, the transmission rate controlled by TFRC is slow to adapt to rapidly changing available bandwidth, leading to inefficient network usage and potential packet loss when increasing the transmission rate, which disrupts image and sound quality.
Innovation Solution
A transmission rate control system that includes a communication history storage unit, round-trip delay time calculation unit, and target transmission rate calculation unit to quickly adjust the transmission rate based on past communication data and current network conditions, allowing for a rapid change to a target bit rate when bandwidth changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If TFRC is used to control transmission rate, then transmission rate changes smoothly, but transmission rate cannot be changed rapidly when bandwidth changes
Solution Approach 1:
The system performs preliminary actions by calculating and storing loss event intervals and their weights in advance. When bandwidth changes occur, the pre-calculated weighted loss event intervals enable rapid transmission rate adjustment without compromising smoothness, as the computational foundation is already prepared.
Solution Approach 2:
The system dynamically adapts between two operational modes: using traditional TFRC for stable conditions and a rapid adjustment mode for changing bandwidth conditions. The loss event interval calculation mechanism switches between smooth weighted averaging and rapid response based on current network conditions, enabling both stability and speed as needed.
2Productivity
If transmission rate is increased rapidly to match available bandwidth, then network efficiency improves, but packet loss occurs which disrupts image and sound quality
Solution Approach 1:
The system uses feedback from loss event intervals to dynamically adjust transmission rate. By monitoring packet loss patterns and calculating weighted loss event intervals, the system receives continuous feedback about network conditions, enabling it to increase transmission rate efficiently while preventing excessive rate increases that would cause packet loss and disrupt media quality.
Solution Approach 2:
The system changes the loss event rate parameter dynamically based on observed packet loss patterns. By adjusting this key parameter in response to network conditions, the system can optimize transmission rate to match available bandwidth without causing harmful packet loss, thus maintaining both network efficiency and media quality.
Data Source
AI summary
A first communication terminal which communicates with a second communication terminal through a best effort network includes: a communication history storage unit in which a communication history is stored for each of the communication terminals; and a round-trip delay time calculation unit which calculates a round-trip delay time that occurs in a communication with the second communication terminal. The second communication terminal includes a target loss event rate calculation unit which calculates a target loss event rate that is to be set by the first communication terminal in a communication with the second communication terminal, based on a past transmission rate that is recorded in the communication history and has been realized in the communication with the second communication terminal, and on the round-trip delay time that occurs in the communication with the second communication terminal. The first communication terminal changes a transmission rate which is set at the present time to a target transmission rate which is calculated based on the target loss event rate and the round-trip delay time. According to the transmission rate control device, when it is determined that the bandwidth that is estimated to be available in a communication through the network is rapidly changed, the transmission rate can be changed to a target bit rate in a short time period.