Transparent Proxy Call Admission Control for VoIP WLANs
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Solution Overview
Problem
Existing call admission control schemes in wireless local area networks (WLANs) are inefficient, leading to resource wastage and increased complexity, as they require wireless user terminals to register and reserve bandwidth without ensuring actual usage, and fail to dynamically manage quality-of-service parameters in a mobile environment.
Innovation Solution
A call admission control proxy that monitors call signaling, determines quality-of-service parameters required for voice calls, and propagates this information to wireless access points to decide on accepting or rejecting calls, thereby eliminating the need for user terminals to inform access points of required quality-of-service parameters and avoiding static configuration of call legs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wireless user terminals register with WiFi hotspots and reserve bandwidth, then call admission control is provided, but device complexity and resource wastage increase
Solution Approach 1:
The patent introduces a network entity (gateway or access point) as an intermediary that performs call admission control and bandwidth reservation on behalf of wireless user terminals. This intermediary monitors SIP signaling messages, extracts QoS requirements, and manages bandwidth allocation centrally, eliminating the need for complex registration and reservation logic in each user terminal device.
2Reliability
If bandwidth is reserved for each wireless user terminal, then call admission control is ensured, but resource utilization decreases
Solution Approach 1:
The patent implements dynamic bandwidth allocation where the network entity monitors actual traffic patterns and QoS requirements in real-time. Bandwidth reservations are adjusted dynamically based on current call admission needs rather than being statically allocated to registered users, allowing the system to adapt to changing conditions and avoid wasting bandwidth on users who do not actively use reserved resources.
Solution Approach 2:
The network entity performs preliminary analysis of SIP signaling messages to determine QoS requirements before calls are established. By proactively identifying bandwidth needs through signaling message inspection and extracting SDP information, the system can make informed admission control decisions without requiring users to pre-register or pre-reserve bandwidth, thus avoiding unnecessary resource allocation.
3Device complexity
If static limit on number of wireless user terminals is placed, then resource management is simplified, but resource utilization efficiency decreases
Solution Approach 1:
The patent changes the management approach from static numerical limits to dynamic parameter-based control. The network entity monitors multiple parameters including QoS requirements, bandwidth availability, and traffic patterns to make intelligent admission control decisions. This allows the system to efficiently utilize resources by admitting calls based on actual network conditions and QoS needs rather than arbitrary user count limits.
Data Source
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AI summary
The invention includes a method and apparatus providing call admission control for a wireless local area network (WLAN). A method includes extracting call signaling information from call signaling messages (306) exchanged between a first user terminal (112) and a second user terminal (101) for establishing a voice call, where the second user terminal is being served by a wireless access point (111), and propagating a quality-of-service request (202) toward the wireless access point which may be used by the wireless access point (111) for determining whether or not to accept the voice call. The quality-of-service request includes at least one quality-of-service parameter determined using the extracted call signaling information. The at least one quality-of-service parameter is adapted for use by the wireless access point for determining whether or not to accept the voice call. The wireless access point then provides an indication (203) as to whether it has accepted the voice call (in which case the voice call is completed) or whether it has rejected the voice call (in which case some other call handling may be applied to the voice call).