Receiving Terminal Bandwidth Control via ECN Protocol Modification
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Solution Overview
Problem
Current IPTV systems using constant bit rate encoding do not effectively utilize available bandwidth, leading to inconsistent video quality and limitations in the number of simultaneous streams, while existing congestion avoidance mechanisms in TCP/IP result in equal bandwidth allocation among streams, failing to maintain constant quality video encoding.
Innovation Solution
A method for a receiving terminal to control bandwidth share by modifying the ECN protocol to skip certain congestion experienced markings in acknowledgement packets, allowing for intelligent allocation of bandwidth across multiple data flows, thereby influencing the transmission rate and bandwidth share.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If constant bit rate encoding is used to match reserved bandwidth, then system simplicity is improved, but video quality consistency deteriorates
Solution Approach 1:
Instead of adapting video encoding to match fixed bandwidth reservations, the invention inverts the approach by allowing variable bit rate encoding to dynamically adapt to available bandwidth. The receiver controls the sender's transmission rate by selectively marking ACK packets, enabling VBR encoding to maintain constant quality while utilizing available network capacity efficiently.
Solution Approach 2:
The invention introduces dynamic bandwidth allocation where the transmission rate is no longer fixed but adapts in real-time based on network conditions and receiver buffer status. The receiver dynamically adjusts the congestion window by marking ACK packets, enabling the system to transition from static CBR to dynamic VBR encoding that maintains constant quality.
2Reliability
If fixed bandwidth reservation is used, then bandwidth guarantee is improved, but utilization of total available bandwidth deteriorates
Solution Approach 1:
The invention changes the parameter of bandwidth allocation from fixed reservations to dynamic variable bit rate encoding. By modifying the transmission rate parameter based on actual network conditions and receiver buffer status, the system guarantees minimum quality while maximizing bandwidth utilization through adaptive encoding rates.
Solution Approach 2:
The invention implements feedback control where the receiver monitors network conditions and buffer status, then sends marked ACK packets back to the sender to adjust transmission rate. This closed-loop feedback mechanism ensures bandwidth is allocated efficiently based on actual demand rather than fixed reservations, maintaining quality guarantees while maximizing utilization.
3Productivity
If TCP congestion avoidance is used, then network utility is improved, but bandwidth allocation equality deteriorates
Solution Approach 1:
The invention applies local quality differentiation by allowing each receiver to independently control its bandwidth allocation based on local buffer status and video encoding requirements. Instead of uniform TCP congestion control that treats all flows equally, each stream receives differentiated bandwidth allocation proportional to its quality requirements, with receivers selectively marking ACK packets to achieve desired bandwidth shares.
4Manufacturing precision
If VBR encoding is used, then video quality is improved, but transmission rate stability deteriorates
Solution Approach 1:
The invention implements feedback control where the receiver monitors network conditions and buffer status, then sends marked ACK packets back to the sender to adjust transmission rate. This closed-loop feedback mechanism smooths transmission rate variations by preventing buffer overflow and underflow, allowing VBR encoding to maintain constant quality while stabilizing the effective transmission rate through adaptive congestion control.
Data Source
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AI summary
There is proposed a modification to the ECN protocol to remove the one-to-one relationship between the network signalling congestion and the sender response to that congestion. The result is to allow a receiver terminal to exhibit some control of bandwidth share relative to other receiver terminals. The idea is to calculate the average CE arrival frequency from received data packets and to set ECE flags at a rate determined as a function of the average CE arrival frequency. Preferably, the function is a multiplier applied to the average CE arrival frequency. The effect of averaging the CE arrival frequency as well as application of a multiplier is a decoupling of the ECE marked ACKs sent by a receiver to the sender, and control of the resulting transmission rate at the sender.