HARQ Combining for 5G Multicast Reliability
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Solution Overview
Problem
Current 5G multicast transmission systems lack reliability due to the absence of feedback mechanisms, leading to inefficient retransmissions that waste energy and computational resources, as they must cater to the weakest user's signal quality for all recipients.
Innovation Solution
Implementing a method where user equipment (UE) receives additional retransmissions on secondary beams in addition to the main beam, allowing successful decoding confirmation and sending NACK messages for unsuccessful decoding, enabling targeted retransmissions with redundancy coding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multicast transmission is performed without feedback mechanisms, then the system can operate simply without ACK/NACK signaling, but the reliability of transmission deteriorates because retransmissions must cater to the weakest user's signal quality for all recipients
Solution Approach 1:
The patent applies local quality by enabling individual UEs to provide feedback (ACK/NACK) based on their own reception quality rather than requiring all UEs to follow the weakest link. Each UE independently evaluates its own signal quality and provides targeted feedback, allowing the base station to perform selective retransmissions tailored to specific users' needs rather than broadcasting to all users uniformly.
2Reliability
If retransmissions are performed for all users without selective feedback, then the system ensures coverage for the weakest user, but energy and computational resources are wasted due to unnecessary retransmissions for users who already received the signal successfully
Solution Approach 1:
The patent implements feedback mechanisms where UEs send ACK/NACK signals to the base station based on their individual reception outcomes. This feedback enables the base station to identify which specific UEs failed to decode the multicast transmission successfully and perform targeted retransmissions only to those UEs, rather than broadcasting to all users. This resolves the contradiction by maintaining reliability for weak users while eliminating energy waste on users who already received the signal successfully.
3Ease of operation
If multicast transmission tailors to the weakest link, then all users experience suitable service quality, but the transmission efficiency deteriorates because the system cannot optimize for the majority of users with better signal conditions
Solution Approach 1:
The patent applies dynamics by transitioning from a static one-size-fits-all transmission approach to a dynamic selective retransmission system. The base station adaptively adjusts retransmission behavior based on real-time feedback from individual UEs. Users with good signal quality experience faster service as they don't require retransmissions, while users with poor signal quality still receive the necessary retransmissions, thereby optimizing overall transmission efficiency while maintaining service quality for all users.
Data Source
AI summary
The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Disclosed is a method of performing multicast transmission in a telecommunication system comprising: a base station, gNB, transmitting a message to a plurality of User Equipments. UEs, on a plurality of beams from the base station; one of the plurality of UEs receiving the message via a main beam and one or more additional beams; the one of the plurality of UEs combining the messages received via the main beam and the one or more additional beams and decoding the message.