Multicast Data Retransmission Using UE Packet Feedback
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Solution Overview
Problem
The efficiency of sending paging indication messages in multicast broadcast services is low, and UEs may miss multicast data if they access the network after data transmission has begun, leading to inefficiencies in resource utilization and data reception.
Innovation Solution
A data transmission method and apparatus that allows terminal devices to report missed multicast data packets to the access network, enabling the network to resend them in a point-to-point mode, and optimizes paging by using configuration information and timing adjustments based on core network parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If multicast mode is used to send MBS service to multiple UEs, then air interface resources and spectrum utilization are improved, but paging indication message transmission efficiency deteriorates because a paging indication message needs to be triggered for each UE in a group
Solution Approach 1:
The patent segments the multicast service data transmission into two modes: PTM (point-to-multipoint) mode for efficient multicast delivery and PTP (point-to-point) mode for individual data retransmission. This segmentation allows the system to maintain high efficiency for multicast while addressing individual UE needs without triggering separate paging messages for each UE.
Solution Approach 2:
The patent introduces a feedback mechanism where the terminal device reports the sequence number of the last received data packet to the access network device. This feedback enables the network to identify which data packets need retransmission and send them via PTP mode, eliminating the need for inefficient paging messages for each individual UE.
2Speed
If the core network or base station starts to send multicast service data without advance notice, then data transmission speed is improved, but UEs that access the network after data transmission begins may miss data packets
Solution Approach 1:
The patent applies preliminary action by having the terminal device report its received data packet sequence number before the data transmission begins or at the start of the multicast session. This allows the access network device to know the terminal's reception status in advance and prepare for any potential data loss, ensuring reliability without slowing down the transmission.
Solution Approach 2:
The feedback mechanism where the terminal reports its last received packet sequence number enables the network to track which data has been successfully received and which packets may have been missed. This feedback loop ensures that even if data transmission speed is high, any missed packets can be reliably retransmitted through PTP mode.
3Reliability
If unicast mode is used to send MBS service to each UE, then data delivery reliability is improved, but resource consumption increases because bearers dedicated for large quantity of UEs need to be established
Solution Approach 1:
The patent segments the data delivery approach by using PTM mode for multicast data transmission to multiple UEs simultaneously, which reduces resource consumption. For individual data retransmission needs, it uses PTP mode. This segmentation allows the system to achieve reliability for each UE while avoiding the resource exhaustion problem of establishing separate bearers for every UE.
Solution Approach 2:
The patent makes the multicast bearer universal by allowing multiple UEs to share the same bearer for receiving multicast data in PTM mode. This multi-functionality enables the system to serve multiple UEs with a single bearer, significantly reducing resource consumption while maintaining data delivery reliability through the combination of PTM and PTP modes.
Data Source
AI summary
An access network device receives first indication information sent by a terminal device, where the first indication information indicates an identifier of a data packet of a multicast service that has been received by the terminal device; the access network device determines a target data packet based on the first indication information; and the access network device sends the target data packet to the terminal device. The terminal device reports the identifier of the received data packet of the multicast service, so that the access network device may determine, based on the identifier, a data packet that is of a multicast service and that has been sent but has not been received by the terminal device.