Wireless Terminal Link Selection with Hysteresis Feedback
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Solution Overview
Problem
Wireless terminals often have better information about downlink quality than network elements, and core network elements are not aware of current traffic loading conditions, making it difficult to select the optimal communication link for routing traffic effectively.
Innovation Solution
A wireless terminal measures signal quality across multiple links and signals its preferred link to base stations, allowing them to consider both link quality and traffic conditions for routing decisions, while also implementing hysteresis to stabilize link changes and prevent rapid switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wireless terminal uses the link with better channel conditions for routing traffic, then the communication quality is improved, but the system cannot consider traffic loading conditions at the base station
Solution Approach 1:
The wireless terminal provides feedback to the base station about its preferred link based on channel conditions. The base station uses this feedback along with its own traffic loading information to make the final link selection decision, combining both perspectives for optimal routing
Solution Approach 2:
The wireless terminal acts as an intermediary that translates its channel quality observations into preferred link indicators, which are then combined with base station traffic conditions to determine the actual link used for data transmission
2Reliability
If the wireless terminal frequently switches between links based on changing channel conditions, then the communication quality is optimized, but rapid link switching occurs causing instability
Solution Approach 1:
Hysteresis margins are applied as a cushion against frequent switching. The terminal only switches links when the alternative link's quality exceeds the current link's quality by a predetermined margin, preventing switching due to minor fluctuations
Solution Approach 2:
The hysteresis margin acts as a parameter threshold that must be exceeded before link switching occurs. This parameter change requirement stabilizes the system by requiring significant quality differences before changing the link state
Data Source
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AI summary
Methods and apparatus for maintaining, selecting and indicating a preferred communications link with an access node, e.g., base station, are described.