Call Admission Control Using Channel Occupancy CDFs
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Solution Overview
Problem
In telecommunications systems with shared-access resources, it is challenging to predict and manage the variation in channel occupancy due to the movement of terminals, which affects call admission decisions, especially when multiple terminals are competing for bandwidth.
Innovation Solution
A channel utilization manager uses pre-determined, statistically justified values to represent channel occupancy, incorporating cumulative distribution functions (CDFs) that account for the variability in data rates and transmission requirements of terminals, ensuring that new calls do not exceed a specified bandwidth threshold with a high confidence level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If call admission control is implemented in shared-access systems to manage bandwidth, then quality of service is improved, but device complexity increases due to the need for probabilistic modeling and CDF calculations
Solution Approach 1:
The patent pre-calculates cumulative distribution functions (CDFs) for channel occupancy during the call admission phase, before actual channel usage begins. These CDFs model the probabilistic behavior of shared channel access and are stored for rapid lookup during call admission decisions, eliminating the need for complex real-time probabilistic calculations
Solution Approach 2:
The patent introduces CDF tables as an intermediary between the call admission control logic and the actual shared channel. These tables pre-compute and store the probabilistic relationships between number of active calls and channel occupancy, serving as a lookup mechanism that simplifies the admission decision process while maintaining accuracy
2Reliability
If statistical methods with high confidence levels are used to determine channel occupancy, then quality of service reliability is improved, but processing time increases due to complex calculations
Solution Approach 1:
The patent performs complex statistical calculations and CDF computations in advance, during system initialization or call setup phases. The results are stored in pre-computed tables that can be rapidly queried during actual call admission decisions, separating the computationally intensive work from the time-critical decision-making process
Solution Approach 2:
The patent uses pre-computed CDF tables that can be quickly generated and discarded or updated as needed. These tables represent statistical models that are computationally expensive to create but inexpensive to use during call admission, allowing the system to benefit from accurate probabilistic modeling without the ongoing computational burden
3Productivity
If multiple terminals are allowed to share the communication channel simultaneously, then resource utilization is improved, but channel occupancy variability increases due to terminal movement
Solution Approach 1:
The patent models channel occupancy as a dynamic probabilistic variable rather than a fixed value. It uses cumulative distribution functions to capture the variability in channel usage caused by terminal movement and competing access patterns, allowing the system to adapt admission decisions to the statistical characteristics of current channel conditions
Solution Approach 2:
The patent changes the parameter representation from deterministic values to probabilistic distributions. By using CDFs to represent channel occupancy, the system can account for the range of possible occupancy values and their probabilities, enabling more robust admission control that maintains resource utilization while accommodating natural variability
Data Source
AI summary
As is reflected in the disclosed method and apparatus, the present invention is a technique to account for the variation in channel occupancy of a particular terminal or terminals during the call admission process. Instead, a channel utilization manager accounts for the probabilistic nature of the call admission decision by using a pre-determined, statistically justified value to represent the channel occupancy. The “per-call” channel occupancy value is determined by a number of factors, including the shared-communications channel data rate. Channel occupancy is incorporated into one or more cumulative distribution functions (CDF), which are evaluated by the channel utilization manager as part of the call admission process. In turn, each channel-occupancy CDF of a shared-communications channel can be generated from a CDF of the terminals' data rates on that channel, which data rates can be determined analytically or empirically.