Source Base Station Modulation Management for Handover Data Reliability
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Solution Overview
Problem
In cellular wireless networks, when a user equipment (UE) hands over from one base station to another, the source base station may not transfer all buffered data, leading to performance and user experience issues due to incomplete data delivery during the handover process.
Innovation Solution
The source base station automatically transitions to transmit data using a low-order Modulation and Coding Scheme (MCS) regardless of the Channel Quality Index (CQI) reported by the UE, ensuring reliable delivery of buffered data by switching to a low-order MCS such as Quadrature Phase Shift Keying (QPSK) with a coding rate less than 0.08, even if the CQI corresponds with a higher-order MCS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the base station uses high-order MCS for data transmission, then the data transmission rate is improved, but the reliability of data delivery during handover deteriorates
Solution Approach 1:
The base station dynamically adjusts the MCS order based on handover detection. When handover is detected, the system automatically switches to low-order MCS for buffered data transmission, and returns to high-order MCS after handover completion, making the transmission scheme adaptive to handover conditions
Solution Approach 2:
The system changes the MCS parameter from high-order to low-order during handover events. This parameter change affects the modulation and coding scheme, transforming the transmission characteristics to be more noise-tolerant during the critical handover period
2Reliability
If the base station uses low-order MCS for data transmission, then the reliability of data delivery is improved, but the data transmission rate deteriorates
Solution Approach 1:
The base station identifies handover events in advance through measurement reports and proactively switches to low-order MCS before actual handover occurs. This preliminary action ensures that buffered data is transmitted with higher reliability during the critical handover window
Solution Approach 2:
The system applies low-order MCS only to buffered data transmitted during the handover period, rather than to all data transmissions. This partial application of the lower-rate scheme minimizes the impact on overall transmission efficiency while ensuring reliability when needed
Data Source
AI summary
A method of managing modulation for transmission of data in anticipation of handover. When a source base station is serving a UE and determines that the UE is going to hand over to a target base station, the source base station automatically transitions to transmit data to the UE with a low-order MCS selected without regard to CQIs reported by the UE, or at least to apply an MCS corresponding with a CQI lower than that reported by the UE. By applying a low-order MCS to transmit data to the UE, the source base station may increase the likelihood that the data will arrive successfully at the UE, as the low-order MCS may be more tolerant to noise than higher-order MCSs.