Uplink Control Resource Element Pattern for MCS Indication
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Solution Overview
Problem
In wireless communication systems, cell edge UEs with poor SNR experience a high block error rate in decoding MCS information for CQI bits, leading to unreliable transmission, while UEs closer to the BS can transmit more CQI bits effectively.
Innovation Solution
The method involves determining an uplink control coding rate based on uplink signal quality and applying a pattern of unused resource element locations in uplink control resource elements, allowing successful decoding of MCS information for both cell edge and other UEs by measuring energy and calculating the sum of resource elements, thereby improving SNR and reducing block error rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If variable number of CQI bits are transmitted by UEs, then transmission efficiency is improved for UEs with good SNR, but block error rate increases for cell edge UEs with poor SNR
Solution Approach 1:
The control resource elements are segmented into different groups based on their location patterns. Some resource elements are designated for transmitting CQI bits while others are left unused or used for reference signals. This segmentation allows the system to adapt the number of effective CQI bits transmitted based on UE location and SNR conditions, improving both transmission efficiency and reliability.
Solution Approach 2:
Different quality levels of transmission are applied to different UEs based on their SNR conditions. Cell edge UEs with poor SNR use resource element patterns that ensure reliable decoding (lower effective rate but higher robustness), while UEs with good SNR can utilize more resource elements for higher data rates. This local adaptation resolves the contradiction between efficiency and reliability.
2Measurement precision
If MCS information is transmitted separately for CQI bits, then decoding accuracy is improved, but signal quality requirements increase for cell edge UEs
Solution Approach 1:
The MCS information is embedded within the control resource element pattern itself rather than being transmitted separately. The pattern of used and unused resource elements pre-encodes the MCS indication, allowing the UE to determine the effective code rate directly from the received pattern without requiring separate MCS transmission. This preliminary encoding reduces signal quality requirements while maintaining decoding accuracy.
3Device complexity
If fixed number of bits are used to transmit CQI, then system complexity is reduced, but transmission reliability deteriorates for UEs with poor SNR
Solution Approach 1:
The system transitions from a fixed bit allocation scheme to a dynamic scheme where the effective number of CQI bits transmitted varies based on UE location and SNR conditions. This is achieved by dynamically adjusting the resource element pattern (which resource elements are used vs. unused) rather than changing the total number of allocated resources. The dynamic adaptation improves transmission reliability for cell edge UEs while maintaining manageable system complexity through pattern-based control.
Data Source
AI summary
A mechanism that allows the successful decoding of MCS information of cell edge UEs while retaining the performance for the other UEs of the cell is provided. In one aspect, a UE may determine an uplink control coding rate based on an uplink signal quality. The UE may encode uplink control data based on the uplink control coding rate. The UE may apply a pattern of unused resource element locations in uplink control resource elements based on the uplink control coding rate. The UE may transmit the uplink control resource elements with the pattern of unused resource element locations. In another aspect, an eNB may receive uplink control resource elements. The eNB may determine an uplink control coding rate based on a pattern of resource element locations in the uplink control resource elements. The eNB may decode uplink control data based on the uplink control coding rate.