Measurement-Based Call Admission Control in Media Gateways
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Solution Overview
Problem
Conventional call admission control techniques in media gateways fail to accurately determine available bandwidth, leading to inefficient bandwidth utilization and potential degradation in voice quality due to the uncertainty in traffic rates caused by VoIP encoding techniques like compression and silence suppression.
Innovation Solution
A measurement-based call admission control method is implemented in media gateways, where network processors measure bandwidth utilization of IP network interfaces, and a control manager determines whether to admit new VoIP calls based on the required bandwidth and measured utilization, using a decay factor to smooth out temporary fluctuations in bandwidth usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If peak bandwidth is allocated to each new call during call setup, then call admission control can be performed, but bandwidth utilization becomes inefficient and available bandwidth cannot be accurately determined
Solution Approach 1:
The system implements measurement-based call admission control by continuously monitoring actual bandwidth utilization on network interfaces and using this feedback to make dynamic admission decisions. The control manager receives bandwidth utilization measurements from network interfaces and compares them against required bandwidth for new calls, enabling accurate determination of available bandwidth based on real-time conditions rather than static peak allocations
Solution Approach 2:
The system changes the parameter used for bandwidth determination from fixed peak bandwidth values to dynamic measured bandwidth utilization. By transitioning from predetermined bandwidth allocations to real-time measurements, the system adapts bandwidth availability assessments to actual network conditions, improving both accuracy and efficiency
2Loss of energy
If VoIP encoding techniques like compression and silence suppression are used, then bandwidth consumption is reduced, but traffic rate becomes non-deterministic and difficult to predict
Solution Approach 1:
The system uses self-service measurement capabilities built into the network interfaces to directly observe actual bandwidth utilization. Rather than attempting to calculate or predict traffic rates through encoding parameters, the network interfaces themselves provide accurate measurements of actual bandwidth consumption, making the system immune to the non-deterministic nature of compressed VoIP traffic
Solution Approach 2:
The system replaces the mechanical calculation approach (predicting bandwidth based on encoding parameters and traffic models) with a measurement-based approach. Instead of using complex traffic rate prediction mechanisms, the system directly measures actual bandwidth utilization, substituting prediction mechanics with empirical observation
3Ease of operation
If conventional call admission control allocates peak bandwidth, then call setup is simplified, but available bandwidth is overestimated and voice quality may degrade
Solution Approach 1:
The system maintains call setup simplicity while improving voice quality reliability by implementing feedback-based admission control. The control manager receives real-time bandwidth utilization measurements from network interfaces and uses this feedback to make accurate admission decisions, ensuring that voice quality is maintained through proper bandwidth management without complicating the call setup process
Data Source
AI summary
Methods and systems for measurement-based call admission control in a media gateway are disclosed. A request for establishing a new voice-over-IP (VoIP) call for sending and receiving voice over IP packets in a media gateway is received. The request indicates a required bandwidth for the new call. Bandwidth utilization of at least one Internet protocol (IP) network interface for sending and receiving voice over IP packets in the media gateway is determined. The media gateway determines whether to admit the new VoIP call based on the determined requested bandwidth for the new call and the determined bandwidth utilization for at least one of the IP network interfaces.