Round-trip estimation for dynamic bit rate adaptation
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Solution Overview
Problem
Real-time Transport Protocol (RTP) does not effectively address network congestion, leading to impaired audio and video quality due to lack of real-time monitoring and error correction, causing delays in detecting increased network latency.
Innovation Solution
A method that calculates both standard and current round-trip times by transmitting packets with unique identification values and receiving corresponding acknowledgement packets, allowing for immediate detection of unused network bandwidth and dynamic adjustment of bit rates to optimize media stream configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RTCP reports are transmitted periodically to monitor network quality, then quality of service monitoring is achieved, but network latency detection is delayed
Solution Approach 1:
The patent applies preliminary action by having the receiving device send RTCP reports immediately upon receiving an RTP packet, rather than waiting for a periodic schedule. This allows the sending device to detect network latency changes as soon as they occur, eliminating the delay inherent in periodic reporting while maintaining continuous QoS monitoring.
Solution Approach 2:
The patent implements feedback by establishing a direct acknowledgment mechanism where the receiving device sends RTCP reports back to the sending device to confirm packet receipt. This feedback loop enables real-time detection of network latency by comparing the transmission time of RTP packets with the receipt time of corresponding RTCP reports, allowing immediate response to bandwidth changes.
2Reliability
If pre-buffers are increased to handle network variability, then buffering issues are reduced, but latency is increased
Solution Approach 1:
The patent applies dynamics by making the bit rate adaptive rather than fixed. The sending device continuously monitors network latency using RTCP acknowledgment reports and dynamically adjusts the media stream bit rate in real-time. This allows the system to respond quickly to network bandwidth changes without relying on large pre-buffers, thereby maintaining low latency while preventing buffering issues through active rate adaptation.
Data Source
AI summary
A networking arrangement is comprises a first network device for transmitting a data stream to a second network device over a network, the method comprises: transmitting a series of first packets to the second network device, each of the first packets having an transmission time and comprising a unique identification value, receiving, from the second network device, a second packet, the second packet indicating receipt of a least one of the first packets by the second network device, determining a standard round-trip time and determining a current round-trip time in dependence on a transmission time of an oldest first packet for which no indication of receipt has been received, and a receipt time of a most recently received second packet, determining an unused network bandwidth between the first network device and the second network device in dependence on the current round-trip time and standard round-trip time.