Modulation and Coding Scheme Selection Using Signal Quality Tables
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Solution Overview
Problem
Conventional rate selection algorithms in wireless communication systems, particularly those using directional antenna systems, struggle to quickly adapt to abrupt changes in signal quality due to changes in beam patterns or blockages, leading to suboptimal modulation and coding scheme selections.
Innovation Solution
Implementing a system that monitors signal quality and uses tables mapping signal quality ranges to corresponding modulation and coding scheme parameters, allowing for rapid selection of new schemes when significant changes occur, thereby ensuring optimal communication performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional rate selection algorithms are used, then the system operates with simple periodic goodput calculations, but the system cannot quickly adapt to abrupt changes in signal quality
Solution Approach 1:
The system pre-calculates and stores goodput values for multiple MCS options in lookup tables before they are needed. When signal quality changes occur, the system can immediately query these pre-computed tables rather than calculating goodput in real-time, enabling rapid MCS adaptation without computational delay
Solution Approach 2:
Lookup tables serve as an intermediary between signal quality measurements and MCS selection decisions. The tables map signal quality ranges to optimal MCS choices, allowing the system to quickly translate abrupt signal changes into appropriate rate adjustments without complex real-time analysis
2Ease of manufacture
If the system uses periodic goodput calculations to determine MCS changes, then the algorithm remains simple to implement, but the MCS selection becomes suboptimal during abrupt signal quality changes
Solution Approach 1:
Goodput calculations are performed in advance for various MCS options and signal quality conditions, with results stored in lookup tables. This pre-computation maintains algorithmic simplicity while ensuring accurate goodput values are immediately available when signal quality changes occur, eliminating the delay and inaccuracy of periodic recalculations
Solution Approach 2:
The system changes the operational parameters of the rate selection algorithm by transitioning from continuous periodic calculations to event-driven table lookups. This parameter change maintains implementation simplicity while dramatically improving responsiveness and accuracy during abrupt signal quality transitions
Data Source
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AI summary
In adaptive modulation and coding scheme (MCS) selection for directional antenna systems, at least one table is defined that maps different ranges of signal quality values to different sets of MCS parameters. In some implementations, each range corresponds to a separate table (e.g., a given table will include the MCS and other information for that range of signal quality values). In the event an abrupt change in signal quality is detected (e.g., a change in received signal strength greater than or equal to a defined threshold), instead of using a conventional rate selection algorithm, a new MCS is selected through the use of the ranges from the table(s). In this way, a relatively large change in MCS may be accommodated, if warranted by the change in signal quality.