Multicast DRX Retransmission Switching for Low-Latency UE Reception
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Solution Overview
Problem
The challenge in wireless communication systems is to efficiently manage multicast data transmission and reception using discontinuous reception (DRX) operations to minimize latency and resource utilization, particularly in applications sensitive to delay or latency.
Innovation Solution
A method for a user equipment (UE) to receive multicast data via PTM transmission and, upon failure, switch to PTP transmission for retransmission without additional latency by sending a NACK during DRX operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the UE uses DRX operations to monitor multicast data during PTM transmission, then power consumption is reduced and resource utilization is optimized, but data reception reliability deteriorates when the UE misses transmission opportunities during sleep periods
Solution Approach 1:
The UE performs preliminary actions by sending a NACK signal during DRX operations to pre-request retransmission before actually needing the data. This allows the network to prepare and send retransmitted data in advance, ensuring data availability when the UE wakes up from sleep mode, thus maintaining reliability while preserving power savings.
Solution Approach 2:
The NACK signal acts as an intermediary mechanism between the UE and the network. When the UE misses multicast data during DRX sleep periods, it sends a NACK that mediates the retransmission process, triggering the network to send the missed data through PTP transmission without requiring the UE to be continuously awake.
2Reliability
If the UE continuously monitors multicast data to ensure reliable reception, then data reception reliability is improved, but power consumption increases and resource utilization deteriorates
Solution Approach 1:
The system implements periodic action through DRX operations where the UE alternates between sleep and wake periods. During sleep periods, the UE conserves power by not monitoring, but can still receive data reliably through the NACK-triggered retransmission mechanism that operates periodically when the UE wakes up.
Solution Approach 2:
The UE performs self-service by autonomously sending NACK signals when it detects missed data during DRX operations. This self-initiated request mechanism allows the UE to maintain reliable reception without continuous network assistance or continuous monitoring, reducing power consumption while ensuring data integrity.
3Reliability
If the UE switches from PTM to PTP transmission for retransmission, then data reception reliability is improved, but resource utilization deteriorates due to additional signaling overhead
Solution Approach 1:
The system applies local quality by using different transmission modes for different purposes: PTM (Point-to-Multipoint) is used for initial bulk data transmission to efficient resource utilization, while PTP (Point-to-Point) is used locally and selectively only when retransmission is needed. This differentiated approach maintains overall resource efficiency while ensuring reliable reception when necessary.
Solution Approach 2:
The system changes transmission parameters dynamically based on reception status. When the UE successfully receives multicast data via PTM, the system maintains efficient PTM operation. When data reception fails, the system changes the transmission mode parameter to PTP for retransmission, optimizing reliability without permanently increasing resource overhead.
Data Source
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AI summary
The present invention relates to a method of receiving data units by a user equipment (UE) in a wireless communication system. In particular, the method includes the steps of: receiving the data unit during an active time of a first discontinuous reception (DRX) configuration related to a multicast transmission for a Hybrid Automatic Repeat and request (HARQ) process; transmitting a negative response to the network based on the data unit being not successfully decoded; starting a HARQ Round-trip Time (RTT) timer of a second DRX configuration related to a unicast transmission for the HARQ process; and monitoring a physical downlink control channel (PDCCH) related to a retransmitted data unit during an active time of the second DRX configuration, based on the HARQ RTT timer expiring.