PDCP Reception Status Reporting for Relay Path Switching
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Solution Overview
Problem
In LTE Rel-15, when a communication path between remote UE and a base station is switched from a non-direct path to a direct path, the base station is unaware of the downlink data receiving status of the remote UE, leading to potential data loss due to buffering limitations, out-of-order delivery, and packet loss.
Innovation Solution
Implement a data receiving status reporting method where the relay UE or remote UE reports the receiving status of downlink data to the base station, allowing the base station to adjust transmission rates, manage buffer data, and ensure sequential delivery of data packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the base station sends downlink data to the remote UE through the relay UE without receiving status reports, then the transmission can continue without interruption, but data loss occurs due to buffering limitations and unknown reception status
Solution Approach 1:
The patent implements a status report mechanism where the remote UE sends feedback to the base station about its downlink data reception status. The status report includes information about successfully received packets and packets that need retransmission, enabling the base station to adjust its transmission based on actual reception conditions.
Solution Approach 2:
The patent uses a polling mechanism where the base station proactively requests status reports from the remote UE before potential data loss occurs. This preliminary action allows the base station to know the reception status in advance and take appropriate corrective measures.
2Reliability
If the base station buffers data for retransmission, then data loss can be prevented, but buffer resources are consumed and transmission efficiency decreases
Solution Approach 1:
The status report mechanism provides real-time feedback to the base station about which packets have been successfully received and which need retransmission. This allows the base station to manage its buffer more efficiently by only retaining packets that are actually needed for retransmission.
Solution Approach 2:
The patent dynamically adjusts transmission parameters based on the reception status reported by the remote UE. When packets are successfully received, the base station can stop buffering and retransmitting them, thereby reducing buffer usage and simplifying buffer management.
3Speed
If the base station continues transmitting data without status information, then transmission rate can be maintained, but out-of-order delivery and data loss occur during path switches
Solution Approach 1:
The status report mechanism provides the base station with information about packet reception status, enabling it to adjust transmission timing and sequence to maintain in-order delivery during path switches between direct and relay communication modes.
Solution Approach 2:
By obtaining status reports before path switches occur, the base station can proactively adjust its transmission strategy to ensure that packets are delivered in the correct order, preventing out-of-order delivery during transition periods.
Data Source
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AI summary
Embodiments of the present invention provide a data receiving status reporting method and an apparatus, and relate to the communications field. The method includes: determining, by first user equipment, a status of receiving at least one packet data convergence protocol layer protocol data unit PDCP PDU by second user equipment, where the at least one PDCP PDU is forwarded by the first user equipment to the second user equipment after being received by the first user equipment through a communications link between the first user equipment and a network device; and sending, by the first user equipment, a first status report to the network device, where the first status report is used to indicate the status of receiving the at least one PDCP PDU by the second user equipment.