NDI Processing in Random Access HARQ Control
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Solution Overview
Problem
In mobile communication systems like LTE, the processing of new data indicators (NDI) during random access procedures can lead to errors in signal transmission and reception due to confusion between new data transmission and retransmission, especially when NDI values received during and after the procedure are not properly managed.
Innovation Solution
A method where the user equipment receives uplink and downlink grant signals with NDI indicators, ignoring NDI values received using temporary cell identifiers during the random access procedure to determine retransmissions based on toggled NDI values received after the procedure through cell identifiers, ensuring accurate data transmission and reception using HARQ schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NDI values received during random access procedure are stored and used for retransmission determination, then HARQ retransmission control is enabled, but errors occur in signal transmission and reception due to confusion between new data and retransmission
Solution Approach 1:
The patent segments the NDI processing by creating separate handling paths for NDI values received during random access procedure versus those received after random access completion. NDI values received during random access using temporary cell identifiers are discarded, while NDI values received after random access using valid cell identifiers are stored and used for retransmission determination. This segmentation eliminates the harmful confusion between new data and retransmission while preserving necessary HARQ control functionality.
2Object-affected harmful factors
If NDI values received during random access procedure are ignored, then transmission errors are prevented, but proper NDI processing for retransmission determination may be affected
Solution Approach 1:
The patent introduces an intermediary condition based on the timing and identifier type: NDI values received during random access procedure using temporary cell identifiers are filtered out, while NDI values received after random access completion using valid cell identifiers are processed normally. This intermediary filtering mechanism prevents transmission errors while ensuring that valid NDI values are properly stored and used for retransmission determination, thus maintaining HARQ control accuracy.
Data Source
AI summary
A method for transmitting an uplink signal by a user equipment (UE). The method includes receiving an uplink grant including a new data indicator (NDI) on a physical downlink control channel (PDCCH) from a network, determining whether the PDCCH is not addressed to a temporary cell identifier, determining whether the NDI has been toggled when the PDCCH is not addressed to the temporary cell identifier, and transmitting a new data to the network when the NDI has been toggled.