Call Admission Control in Wireless Networks
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Solution Overview
Problem
Current wireless network architectures face inefficiencies and call quality degradation due to wireless stations roaming between access points, requiring new IP addresses and VLAN assignments, leading to network disruptions and poor call handling capacity.
Innovation Solution
A network switch system that maintains Association and Bridge listings to manage VLAN mobility and implement call admission control by determining reservation and call capacity thresholds, rejecting new associations when thresholds are met to prevent call quality degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wireless stations are allowed to roam freely between access points, then mobility and adaptability are improved, but network stability and call quality deteriorate due to frequent IP address changes and VLAN reassignments
Solution Approach 1:
The system performs preliminary actions by pre-establishing VLAN membership information in the network switch before the wireless station actually roams. When a station roams to a new access point, the switch already has the pre-stored VLAN information, allowing immediate and seamless VLAN reassignment without disruption to ongoing calls.
Solution Approach 2:
The system implements feedback mechanisms where the network switch monitors and tracks VLAN membership information of wireless stations. This feedback loop allows the switch to maintain accurate records of which VLAN each station belongs to, enabling proper VLAN reassignment during roaming while preserving call quality.
2Adaptability or versatility
If access points continuously accept new wireless station associations, then network coverage and connectivity are improved, but call quality and network efficiency deteriorate due to unlimited call handling capacity
Solution Approach 1:
The network switch performs preliminary evaluation of admission criteria before allowing new wireless stations to associate with access points. By pre-determining whether a station should be allowed to join based on predefined policies and available resources, the system prevents premature or inappropriate associations that would degrade call quality.
Solution Approach 2:
The system continuously monitors network conditions and provides feedback to control admission of new stations. The switch tracks current call capacity and VLAN membership, using this feedback to dynamically decide whether to allow new associations, thereby maintaining optimal call quality while preserving network coverage.
3Ease of operation
If the network allows unlimited wireless station associations, then ease of operation and connectivity are improved, but network overload and call quality degradation occur
Solution Approach 1:
The network switch implements continuous feedback monitoring of call capacity and network load. This feedback mechanism allows the system to automatically control and regulate the number of active associations, preventing network overload while maintaining simple operation for legitimate users.
Solution Approach 2:
The system dynamically changes operational parameters such as admission thresholds and call capacity limits based on real-time network conditions. By adjusting these parameters, the network maintains optimal performance and prevents overload while preserving ease of connection for authorized stations.
Data Source
AI summary
An association request from a wireless station is received at an access point. A determination is made whether a reservation threshold for a pre-determined number of wireless stations for the access point has been met. If the reservation threshold has not been met, the wireless station is associated with the access point. If the reservation threshold has been met, and the wireless station is not already on a call through another access point, the association of the wireless station with the access point is rejected.