Semi-Static HARQ-ACK Codebook Determination for Unlicensed Carriers

The patent applies dynamics by making the HARQ-ACK codebook determination adaptive rather than fixed. The UE and BS dynamically adjust the codebook size based on actual transmission outcomes. When LBT fails or hidden node interference occurs, the system dynamically retransmits HARQ-ACK feedback with updated codebook sizes, transforming the static semi-static determination into a dynamic process that responds to real-time channel conditions.

The patent implements feedback mechanisms where the UE monitors downlink assignments and provides feedback about HARQ-ACK transmission status. The BS receives this feedback and adjusts subsequent transmissions accordingly. This closed-loop feedback system enables both UE and BS to understand whether previous HARQ-ACK feedback was successfully received, preventing unnecessary retransmissions and improving overall reliability.

The patent uses feedback to ensure both UE and BS arrive at the same codebook size understanding. The UE determines the codebook size based on received downlink assignments and transmits HARQ-ACK feedback. The BS uses this feedback to verify its understanding of the codebook size and adjusts if necessary. This mutual feedback mechanism eliminates misunderstandings while keeping the determination process relatively simple.

The patent creates a universal codebook determination mechanism that works for both initial transmissions and retransmissions. The same feedback-based approach is used regardless of whether it's the first HARQ-ACK feedback or a retransmission, providing a unified solution that maintains consistency between UE and BS across different transmission scenarios.