MCS Management for Trunking Group Reliability
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Solution Overview
Problem
The existing LTE technology is not applicable to digital trunking communication systems due to differences in modulation and coding schemes between point-to-point and point-to-multipoint services, where users without speaking rights lack uplink channels and HARQ feedback, making it difficult to ensure reliable data transmission for all group users.
Innovation Solution
A method and system that dynamically adjust the modulation and coding scheme by having the base station compare and update the MCS values based on the minimum CQI reported by trunking terminals, using a timer to control CQI reporting frequency and adjusting outer loop values to ensure reliable data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional LTE AMC mode is used for trunking service, then system throughput is improved under good channel conditions, but transmission reliability deteriorates for users without speaking rights who lack uplink channels and HARQ feedback
Solution Approach 1:
The patent applies local quality by differentiating MCS management for users with speaking rights (who have uplink channels) versus users without speaking rights (who lack uplink channels). For users without speaking rights, the base station uses downlink-only CQI feedback and adjusts MCS without relying on uplink HARQ feedback, ensuring reliable transmission adapted to their specific constraints while maintaining high throughput for others
Solution Approach 2:
The patent implements dynamic MCS adjustment by continuously monitoring downlink channel quality through CQI feedback and adapting the MCS index in real-time. The base station dynamically selects appropriate MCS values from codebooks based on current channel conditions, enabling the system to track link changes and optimize both throughput and reliability under varying conditions
2Adaptability or versatility
If traditional LTE point-to-point AMC is applied to point-to-multipoint trunking service, then individual user link adaptation is achieved, but group-wide reliable demodulation cannot be ensured for all users with random distribution
Solution Approach 1:
The patent merges individual user CQI feedback into a group-level MCS decision process. The base station collects CQI reports from multiple users in the group, processes them collectively, and determines a single MCS value that ensures reliable demodulation for all users in the group, including those with random distributions and varying channel conditions
Solution Approach 2:
The patent implements feedback mechanisms where users without speaking rights provide downlink CQI feedback through available channels. This feedback loop enables the base station to adjust MCS based on actual group channel conditions, ensuring that the selected MCS is appropriate for the worst-case user in the group while maintaining adaptability
3Measurement precision
If users without speaking rights report CQI frequently, then channel quality tracking is improved, but uplink resource consumption increases for users who already lack uplink channels
Solution Approach 1:
The patent implements periodic CQI reporting where users report channel quality at predetermined intervals rather than continuously. This periodic action maintains adequate channel quality tracking precision while significantly reducing uplink resource consumption and energy usage for users without speaking rights
Solution Approach 2:
The patent applies partial action by having only certain users (particularly those without speaking rights) report CQI at reduced frequencies compared to full uplink-capable users. This partial reporting strategy provides sufficient channel quality information for MCS adjustment without requiring excessive uplink resources
Data Source
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AI summary
A method and system for managing a modulation and coding scheme (MCS). The method includes: a base station obtaining a downlink channel quality indicator (CQI) when a block error ratio of a trunking terminal reaches a pre-stored block error ratio threshold; the base station comparing a current CQI of a group with a CQI locally stored and reported by the group, wherein the CQI reported by the group is the minimum value in received CQIs reported by trunking terminals in the group respectively; and if a comparison result is that the current CQI of the group is smaller than the CQI reported by the group, the base station initiating an operation of updating an MCS value.