SPS Feedback Sequence Positioning for Accurate ACK/NAK Differentiation
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Solution Overview
Problem
In 3GPP E-UTRA systems, the existing methods for feeding back acknowledgement information of semi-persistent scheduling data packets lead to incorrect feedback and unnecessary retransmissions due to the inability to differentiate between dynamic and semi-persistent scheduling subframes, especially when the SPS activation PDCCH signaling is lost.
Innovation Solution
The method involves placing the ACKs/NAKs of SPS data packets from the (N−k+1)th to the Nth position in the feedback sequence, allowing the base station to correctly receive feedback information and reduce unnecessary retransmissions by ensuring accurate differentiation between dynamic and semi-persistent scheduling subframes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the existing feedback method is used without position differentiation, then the feedback sequence structure is simple, but the base station cannot correctly differentiate between dynamic and semi-persistent scheduling subframes leading to incorrect feedback interpretation
Solution Approach 1:
The feedback sequence is segmented into different position ranges: ACKs/NAKs for dynamic scheduling subframes are placed in positions 1 to (N-k), while ACKs/NAKs for semi-persistent scheduling subframes are placed in positions (N-k+1) to N. This segmentation allows the base station to correctly differentiate between the two types of scheduling subframes based on position alone, resolving the technical contradiction by improving feedback accuracy without requiring complex signaling overhead.
2Reliability
If SPS activation PDCCH signaling is lost, then the UE cannot differentiate SPS subframes from dynamic subframes, but unnecessary retransmissions occur with existing methods
Solution Approach 1:
The UE performs preliminary action by pre-determining the position range for SPS ACKs/NAKs based on the total number of downlink subframes N and the number of SPS subframes k. Even when SPS activation PDCCH signaling is lost, the UE can still place ACKs/NAKs for SPS subframes in the predetermined position range (N-k+1) to N, allowing the base station to correctly identify these as SPS feedback and avoid unnecessary retransmissions, thus improving reliability while reducing energy waste.
3Ease of operation
If ACKs/NAKs for SPS subframes are placed at the beginning of the feedback sequence, then the feedback structure is straightforward, but the base station misinterprets them as feedback for dynamic subframes
Solution Approach 1:
Instead of arranging ACKs/NAKs solely by temporal order of subframes, the invention introduces a new dimension - position-based type identification. By placing SPS ACKs/NAKs in a specific position dimension (positions (N-k+1) to N) rather than mixing them with dynamic subframe feedback at the beginning, the base station can correctly interpret the subframe type information without loss, while the arrangement remains straightforward and easy to implement.
Data Source
AI summary
The application relates to radio communication technologies and discloses a method for receiving semi-persistent scheduling (SPS) data packets and sending acknowledgment information of the SPS data packets. A communication apparatus receives physical downlink shared channel (PDSCH) data packets from a base station. The PDSCH data packets include one or more dynamic scheduling data packets and one or more semi-persistent scheduling (SPS) data packets. The communication apparatus sends, to the base station, a sequence including feedback information of the PDSCH data packets. The sequence includes a plurality of bits. Each bit carries an acknowledgement (ACK) or a negative acknowledgement (NAK) to one PDSCH data packet respectively. The bits carrying acknowledgements of the one or more SPS data packets are arranged at the end of the sequence.