Selective PDCCH Repetition for URLLC Reliability
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Solution Overview
Problem
In wireless communication systems, particularly in 5G and NR, the repetition of physical downlink control channel (PDCCH) transmissions improves reliability but increases overhead, which is significant in ultra-reliable low-latency communications (URLLC) where latency requirements limit the number of transmissions.
Innovation Solution
Implementing selective PDCCH repetition, where transmissions are made without repetition initially and repetition is activated only for retransmissions that fail, conserving resources and improving reliability by using repetition only when necessary, such as when the block error rate (BLER) is below a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCCH repetition is applied to improve reliability, then reliability is improved, but communication overhead increases
Solution Approach 1:
The patent implements dynamic PDCCH repetition activation where the repetition mechanism is selectively enabled or disabled based on transmission conditions. The base station determines whether to activate repetition for a given PDSCH transmission based on factors such as channel conditions, UE capability, and transmission success rate, thereby adapting the repetition behavior to minimize overhead while maintaining reliability when needed.
Solution Approach 2:
The patent changes the parameter of repetition activation status dynamically. By modifying the repetition configuration parameter based on transmission conditions (e.g., activating repetition only when BLER threshold is not met), the system optimizes the balance between reliability improvement and overhead reduction, allowing flexible adjustment of transmission parameters.
2Reliability
If PDCCH repetition is activated for all transmissions, then reliability is improved, but latency increases due to additional transmissions
Solution Approach 1:
The system dynamically adjusts the repetition activation based on transmission conditions to avoid unnecessary repetitions that would increase latency. By evaluating factors such as initial transmission success rate and channel conditions before activating repetition, the system ensures that repetition is only applied when necessary, thereby maintaining low latency for successful transmissions while providing reliability enhancement only when needed.
3Reliability
If transmission resources are allocated for repeated PDCCH, then reliability is improved, but system efficiency decreases
Solution Approach 1:
The patent applies partial repetition action where repetition is not applied to all transmissions but only to a subset of transmissions that require it. By evaluating transmission conditions and activating repetition only when necessary (e.g., when initial transmission fails or channel conditions deteriorate), the system avoids excessive repetition that would waste resources, thereby maintaining high system efficiency while providing reliability enhancement only when needed.
Data Source
AI summary
Certain aspects of the present disclosure provide techniques for selectively activating physical downlink control channel (PDCCH) repetition for retransmissions in wireless communications systems. In an exemplary method, a base station (BS) may transmit, without repetition, a physical downlink shared channel (PDSCH) to a user equipment (UE) in a set of initial transmissions in a period of a transmission cycle; and activate repetition including multiple transmissions for physical downlink control channels (PDCCHs) in a potential retransmission slot for the UE during the period.