Measurement-Based Session Admission Control for Wi-Fi LAN Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing VoIP over Wi-Fi LAN systems face challenges in maintaining high quality due to varying RF bandwidth requirements, interference, and signal strength changes, leading to resource overload and unexpected disconnections, especially in heavily loaded systems.
Innovation Solution
A measurement-based session admission control system that determines RF utilization on a per-access-class basis, incorporating factors like collisions, distance, and interference to prevent voice and video calls from operating in collision regions, allowing data sessions to operate in both regions and enabling bandwidth borrowing between classes to maximize system utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional call admission control algorithms are used to manage bandwidth, then the system can handle basic call volumes, but resource overload occurs when accounting for RF bandwidth variability due to distance and interference changes
Solution Approach 1:
The system dynamically adjusts bandwidth requirements based on real-time RF conditions. As callers move from one access point zone to another, the system recalculates bandwidth needs based on changing distance and interference levels, allowing the admission control to adapt to varying RF conditions rather than using static thresholds
Solution Approach 2:
The system incorporates feedback mechanisms that monitor actual RF bandwidth utilization and adjust admission decisions accordingly. By measuring actual RF conditions and feeding this information back into the admission control algorithm, the system can prevent resource overload while maintaining high call handling capacity
2Productivity
If the system admits more calls to maximize bandwidth utilization, then productivity increases, but voice and video quality deteriorates due to collision region operations
Solution Approach 1:
The system applies different admission control policies to different traffic classes and spatial regions. Voice and video calls are protected from admission into collision regions where quality would deteriorate, while data sessions can operate in both regions. This local differentiation of quality requirements allows high bandwidth utilization without sacrificing voice/video precision
Solution Approach 2:
The system changes admission parameters based on traffic class and RF conditions. By adjusting the collision region admission threshold differently for voice/video versus data traffic, the system maintains high bandwidth utilization while ensuring voice and video calls only operate in regions meeting minimum quality parameters
3Reliability
If the system prohibits voice and video calls from collision regions to maintain QoS, then service quality improves, but bandwidth utilization decreases due to unused RF bandwidth
Solution Approach 1:
The system makes RF bandwidth serve multiple functions by allowing data sessions to operate in collision regions while voice and video sessions operate in non-collision regions. This multi-functional use of the same physical medium maximizes overall bandwidth utilization while maintaining QoS for sensitive traffic classes
Solution Approach 2:
The system applies partial admission control - fully blocking voice/video in collision regions while allowing data sessions there. This partial action approach ensures QoS for critical traffic while utilizing all available bandwidth for less sensitive data traffic, preventing unused RF bandwidth
4Device complexity
If the system uses fixed admission thresholds to simplify control, then device complexity decreases, but the system cannot account for varying distance and interference conditions
Solution Approach 1:
The system performs preliminary measurements of RF conditions including distance to access point and interference levels before making admission decisions. By gathering this information in advance and incorporating it into the admission control logic, the system maintains relatively simple device complexity while achieving high adaptability to varying RF conditions
Data Source
AI summary
A communication system is provided that can control which communication sessions with mobile devices are admitted to a wireless access point. The admission decisions are based on actual measurements of radio frequency (RF) utilization. The RF utilization is determined on a per access class basis. Access classes may be defined by protocol but are, generally, voice, video and data. Thus, the system provides the ability to determine admissions that allows for the incorporation of factors including collisions, the distance from the access point to which a mobile device is communicating, and other factors.