IP Telephone Congestion Control via Call Time-Based Packet Discard
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Solution Overview
Problem
In IP telephone systems, when the number of simultaneous calls exceeds the line capacity, packets are uniformly discarded, leading to uniform deterioration in call quality for all users. This is particularly problematic for the latest call with the shortest call time, where good call quality is most desired.
Innovation Solution
A congestion control method that dynamically sets the packet discard rate for each call based on the number of simultaneous calls and the call time order. The packet discard rate is set to be equal to or less than a predetermined first upper limit value, with higher rates for longer calls and lower rates for shorter calls. Specifically, the packet discard rate of the latest call with the shortest call time is set to be equal to or less than a predetermined second upper limit value, which is lower than the first upper limit value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If packets are uniformly discarded for all calls when line capacity is exceeded, then the packet discard rate is simplified to manage, but the call quality of all calls is uniformly deteriorated
Solution Approach 1:
The patent applies local quality by setting different packet discard rates for different calls based on their call time order. Specifically, the latest call (shortest call time) is assigned a lower packet discard rate to preserve its quality, while earlier calls are assigned higher discard rates. This differentiated approach ensures that critical communications maintain quality while still managing overall line capacity.
2Reliability
If the packet discard rate of the latest call is reduced to maintain its quality, then the call quality of the latest call is preserved, but the overall packet discard rate management becomes more complex
Solution Approach 1:
The patent changes the parameter of packet discard rate from a uniform value to a differentiated value based on call time order. By introducing call time order as a distinguishing parameter and setting the latest call's discard rate to be lower than others, the system preserves critical call quality while managing complexity through a clear hierarchical rule.
3Quantity of substance
If more simultaneous calls are accommodated to increase communication capacity, then the number of users served is increased, but the packet discard rate increases and call quality deteriorates
Solution Approach 1:
The patent enables the system to accommodate more simultaneous calls by applying local quality differentiation. By preserving the quality of the latest call through lower discard rates while allowing higher discard rates for earlier calls, the system can maintain higher overall call volumes without uniformly degrading all call qualities, thus serving more users effectively.
Data Source
AI summary
A congestion control method in an IP telephone system includes acquiring a number of simultaneous calls in one line shared by a plurality of IP telephones, acquiring a call time order corresponding to length of a call time for each call, and controlling a packet discard rate of each call on the basis of the number of simultaneous calls and the call time order. The packet discard rate of each call is set to a predetermined first upper limit value or less. In addition, the packet discard rate is set higher as the call time is longer, and the packet discard rate is set lower as the call time is shorter. Further, the packet discard rate of the latest call having the shortest call time is set to be equal to or less than a predetermined second upper limit value lower than the predetermined first upper limit value.