UE DCI Ordering for Missed Message Detection
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Solution Overview
Problem
In wireless communication systems, user equipment (UE) struggles to determine if it has missed downlink control information (DCI) messages, especially when these messages are transmitted outside of physical downlink control channel (PDCCH) monitoring occasions (PMOs) or multiplexed with physical downlink shared channel (PDSCH) transmissions.
Innovation Solution
The UE is configured with an ordering scheme based on starting symbols or scheduling units of PDSCH transmissions associated with piggyback DCI messages, allowing the UE to determine the order of DCI messages and identify missed messages. This ordering scheme is used in conjunction with cDAI and tDAI values to ensure accurate feedback transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If DCI messages are transmitted outside of PDCCH monitoring occasions or multiplexed with PDSCH transmissions, then the flexibility and capacity of downlink control information transmission is improved, but the ability of UE to determine if DCI messages are missed deteriorates
Solution Approach 1:
The base station performs preliminary actions by transmitting indication information about the order of DCI messages before the UE needs to determine if messages are missed. This indication information is included in the DCI messages themselves, allowing the UE to proactively identify missed messages by comparing the indicated order with the received messages, thus resolving the reliability issue while maintaining transmission flexibility
Solution Approach 2:
The system implements a feedback mechanism where the base station provides indication information about DCI message ordering to the UE. The UE uses this feedback to determine whether it has missed any DCI messages by checking the sequence numbers or order indicators in the received messages, enabling reliable detection of missed messages even when transmitted outside traditional PDCCH monitoring occasions
2Productivity
If DCI messages are multiplexed with PDSCH transmissions, then the efficiency of downlink resource utilization is improved, but the complexity of DCI message ordering and identification increases
Solution Approach 1:
The DCI messages are segmented with individual identification information, such as sequence numbers or order indicators, that divide the overall DCI transmission into distinguishable units. This segmentation allows the UE to independently identify and order each DCI message even when multiplexed with PDSCH transmissions, reducing the complexity of message ordering while improving resource utilization efficiency
Data Source
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Figure 3A~3B
AI summary
Methods, systems, and devices for wireless communication are described. A user equipment (UE) may receive multiple downlink control information (DCI) messages from a base station, where each of the multiple DCI messages schedules a respective downlink transmission. Some of the DCI messages may be multiplexed with downlink transmissions. The UE may identify, for each downlink transmission multiplexed with one of the multiple DCI messages, a time period including a beginning of the downlink transmission, and the UE may determine an order of the multiple DCI messages based on the time period. The UE may transmit a feedback message to the base station for the respective downlink transmissions based on the determined order. The UE may transmit the feedback message to the base station on uplink resources indicated by a last DCI message in the determined order.