Multicast Signal Error Recovery via NACK Feedback
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Solution Overview
Problem
In wireless communication systems, particularly in LTE, there is a challenge in efficiently recovering errors in multicast channels, leading to reliability issues due to the lack of effective mechanisms for handling packet errors and scheduling message decoding failures.
Innovation Solution
A method and apparatus for a user equipment (UE) to receive a multicast signal by attempting to decode the signal, transmitting a data NACK signal upon failure, and optionally a control NACK signal when the control signal is not received, using a common resource and adjusting transmission power based on retransmission times, to enhance error recovery and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multicast signal is transmitted without effective error recovery mechanism, then transmission efficiency is improved, but reliability deteriorates due to packet errors and decoding failures
Solution Approach 1:
The patent implements feedback mechanisms where the UE transmits NACK signals to the network when multicast signal reception or decoding fails. The network uses this feedback to determine whether retransmission is necessary, creating a closed-loop error recovery system that maintains reliability without sacrificing transmission efficiency.
Solution Approach 2:
The patent dynamically adjusts the error recovery process based on reception conditions. The UE attempts to receive and decode multicast signals, and only triggers NACK transmission when decoding fails. This dynamic approach allows the system to maintain high transmission efficiency for successful packets while providing reliable error recovery only when needed.
2Reliability
If separate resources are allocated for control NACK and data NACK signals, then signaling reliability is improved, but resource complexity increases
Solution Approach 1:
The patent merges the resources for control NACK and data NACK signals into a common uplink resource. This consolidation reduces resource management complexity while maintaining signaling reliability, as the network can distinguish between control and data NACK based on the decoding status information provided by the UE.
3Reliability
If retransmission is performed multiple times, then error recovery reliability is improved, but transmission latency increases
Solution Approach 1:
The patent implements a preset limit on the number of retransmission attempts. The network performs retransmission only up to this preset number of times, which provides sufficient error recovery reliability for most cases while avoiding excessive retransmissions that would significantly increase latency. This partial action approach balances reliability and time loss.
Data Source
AI summary
Disclosed in the present application is a method for receiving by a terminal a multicast signal in a wireless communication system. Specifically, the method comprises the steps of: attempting to receive, from a network, a control signal for scheduling a multicast signal; receiving the multicast signal from the network and performing decoding on the basis of the control signal; and transmitting a data negative acknowledgement signal to the network when the decoding of the multicast signal fails, wherein a control negative acknowledgement signal is transmitted to the network when the reception of the control signal has failed.