Wireless Handoff Latency Reduction via Selective Scanning
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Solution Overview
Problem
Current wireless networks experience significant handoff latency due to lengthy scanning phases during the handoff process, particularly in VoIP communications, where the discovery phase accounts for over 90% of the total latency, while reassociation delays are relatively minor.
Innovation Solution
Implementing a selective scanning algorithm and caching mechanism that allows mobile stations to store key information about access points, perform targeted channel scans based on signal strength, signal-to-noise ratio, and available bandwidth, and update caches with new access points, thereby reducing the need for full-channel scans and minimizing probe delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a full-channel scanning algorithm is used during handoff, then the mobile device can discover all available access points, but the scanning time and handoff latency increase significantly
Solution Approach 1:
The patent applies preliminary action by having the mobile device obtain a list of candidate access points from the current access point before initiating scanning. This pre-provided information allows the device to skip scanning channels where no access points are expected, significantly reducing scanning time while maintaining reliable discovery of available access points.
Solution Approach 2:
The patent extracts only the necessary scanning channels from the full channel set by using the candidate access point list to identify which channels actually contain accessible access points. This extraction approach eliminates redundant scanning of channels without access points, reducing handoff latency while preserving complete discovery of usable access points.
2Reliability
If the mobile device scans all channels to ensure complete access point discovery, then no access points are missed, but the processing time and energy consumption increase
Solution Approach 1:
The patent uses preliminary action by obtaining the candidate access point list before scanning begins. This pre-acquired information enables the mobile device to restrict scanning to only those channels where access points are known to exist, ensuring complete detection of accessible access points while dramatically reducing scanning duration compared to scanning all channels.
Solution Approach 2:
The patent applies local quality by concentrating scanning resources on specific channels identified as containing candidate access points, rather than uniformly scanning all channels. This localized scanning approach maintains detection accuracy for accessible access points while reducing overall scanning time and energy consumption.
3Reliability
If the mobile device performs extensive scanning to find the best access point, then the quality of connection is optimized, but the handoff process becomes too slow for real-time applications
Solution Approach 1:
The patent applies preliminary action by obtaining the candidate access point list before handoff begins, enabling the mobile device to quickly evaluate only relevant access points. This approach maintains connection quality optimization by considering all accessible access points while achieving fast handoff speeds suitable for real-time applications like VoIP.
Solution Approach 2:
The patent extracts the subset of channels containing candidate access points from the complete channel set, allowing the mobile device to focus evaluation resources on only those channels that matter. This extraction enables efficient comparison of candidate access points to determine the best connection while maintaining handoff speed requirements.
4Reliability
If the mobile device stores and processes information from all scanned access points, then the most optimal access point can be selected, but the memory usage and processing overhead increase
Solution Approach 1:
The patent extracts only the essential information from candidate access points (such as channel number, signal strength, and basic capabilities) needed to determine the best access point for handoff. This selective information extraction maintains accurate access point selection while minimizing memory usage and processing overhead by storing only the most relevant parameters.
Solution Approach 2:
The patent applies partial action by storing and processing only the necessary subset of access point information required for handoff decision-making, rather than storing all possible parameters from scanned access points. This approach achieves sufficient selection accuracy while reducing data storage requirements and processing overhead.
Data Source
AI summary
In accordance with the present invention, computer implemented methods and systems are provided for reducing handoff latency in a wireless network. In response to detecting that a handoff is necessary, the present invention uses a selective scanning algorithm that includes the use of a channel mask and/or a caching algorithm for detecting one or more new access points.