Virtual Access Point for Wireless Handover Control
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Solution Overview
Problem
Existing methods for handover between heterogeneous wireless networks, such as WLANs and WWANs, face challenges in seamlessly maintaining real-time voice or data calls while reducing false triggering and optimizing power consumption, as they struggle to balance signal quality detection and response.
Innovation Solution
A mobile communication device operates as a virtual access point within the WLAN, using the CAPWAP protocol to perform peer-to-peer communications and mesh networking functions, bridging to the WWAN when signal quality falls below specific thresholds, thereby reducing false handovers and maintaining call stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the mobile device quickly detects signal quality degradation and triggers handover, then the handover response time is reduced and call continuity is improved, but false triggering of handover may occur due to brief temporary degradation
Solution Approach 1:
The system performs preliminary actions by continuously monitoring signal quality parameters (RSSI, RSRQ, SINR) and pre-evaluating handover conditions before actual handover is triggered. This allows the device to prepare for handover in advance while waiting for sustained degradation conditions, thus reducing response time when handover is truly needed while avoiding false triggers from temporary fluctuations.
Solution Approach 2:
The handover decision mechanism dynamically adjusts its sensitivity and triggering thresholds based on current signal conditions and historical trends. The system can adapt the degradation threshold and time-window parameters dynamically, making the handover trigger more conservative when signals are stable and more aggressive when signals are rapidly deteriorating, thus balancing fast response with false trigger reduction.
2Measurement precision
If the mobile device continuously monitors signal quality to detect degradation, then handover detection accuracy is improved, but power consumption increases
Solution Approach 1:
The system implements periodic monitoring of signal quality parameters instead of continuous monitoring. It measures key parameters (RSSI, RSRQ, SINR) at defined intervals and uses these periodic samples to detect sustained degradation. This periodic approach maintains adequate detection accuracy while significantly reducing power consumption compared to continuous monitoring.
Solution Approach 2:
The system uses self-service by leveraging existing signal processing functions and reused measurements for multiple purposes. Signal quality measurements taken for other optimization purposes are also utilized for handover detection, avoiding duplicate measurements and reducing overall power consumption while maintaining detection accuracy.
3Reliability
If the mobile device uses multiple signal quality parameters for handover detection, then the reliability of handover decision is improved, but the complexity of the detection mechanism increases
Solution Approach 1:
The detection mechanism is segmented into distinct functional modules: signal quality measurement module, degradation detection module (comparing parameters against thresholds), and handover triggering module. Each module handles a specific aspect of the detection process, making the overall complex system more manageable and maintainable while still utilizing multiple parameters (RSSI, RSRQ, SINR) for reliable decision-making.
4Duration of action of stationary object
If the mobile device establishes connection with another wireless network before leaving current network, then call continuity is improved, but the time for establishing new connection increases power consumption
Solution Approach 1:
The system performs preliminary actions by pre-scanning and pre-evaluating target wireless networks before handover is triggered. It identifies potential target networks and pre-establishes connection parameters, so that when handover becomes necessary, the actual connection establishment time is reduced. This maintains call continuity while minimizing the extended period of dual-network operation and associated power consumption.
Data Source
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AI summary
To improve network coverage or reduce false handover triggering, at least one client terminal is set to operate as a virtual access point (VAP) in a first wireless network by an AP controller. If a mobile device detects that a signal quality estimate of communications via an AP of the first wireless network is below a first value, the mobile device performs a handover procedure to the VAP. While maintaining the call via the VAP, if the mobile device detects that the signal quality estimate is back above the first value, the mobile device performs a handover procedure back to the AP of the first wireless network. On the other hand, if the mobile device detects that the signal quality estimate is below a second value which is less than the first value, the mobile device performs a vertical handover procedure from the VAP to a base station of a second wireless network.