Compact PTM/PTP Protocol Stacks for Reliable Multicast Retransmission
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Solution Overview
Problem
Existing wireless communication systems face challenges in ensuring reliable multicast transmission and reception, particularly in NR systems, due to the need for efficient uplink feedback and retransmission mechanisms for MBS data packets.
Innovation Solution
A compact protocol stack is implemented at both the UE and base station levels, incorporating independent PTM and PTP logical channels for data reception and transmission, with feedback mechanisms to facilitate retransmissions based on reception status reports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a compact protocol stack with independent PTM and PTP logical channels is implemented, then the reliability of multicast transmission is improved through feedback and retransmission mechanisms, but the device complexity increases due to the need to manage multiple logical channels and protocol entities
Solution Approach 1:
The protocol stack is segmented into independent PTM and PTP logical channels with separate RLC entities, allowing independent management of multicast and unicast traffic flows. This segmentation enables reliable feedback and retransmission through PTP while maintaining efficient multicast delivery through PTM, resolving the contradiction between reliability and complexity by organizing the system into manageable independent components.
Solution Approach 2:
The compact protocol stack design allows a single unified protocol structure to handle both PTM and PTP transmissions, providing multi-functionality. The same protocol entities manage both multicast and unicast traffic, reducing overall device complexity while maintaining reliability through integrated feedback mechanisms.
2Reliability
If feedback reports from each subscriber UE are monitored through corresponding PTP RBs, then the reliability of multicast reception is improved, but the network signaling overhead increases
Solution Approach 1:
Feedback reports from different subscriber UEs are segmented and transmitted through corresponding dedicated PTP RBs rather than a single shared channel. This segmentation allows parallel feedback transmission, improving reliability by preventing feedback collisions while managing signaling overhead through efficient resource allocation.
Solution Approach 2:
The system implements feedback mechanisms where UEs send reception status reports through PTP RBs, enabling the network to identify and retransmit missing packets. This feedback loop improves multicast reception reliability by allowing targeted retransmissions based on actual UE reception status.
3Adaptability or versatility
If mode switches between PTM and PTP are performed based on subscriber count thresholds, then the adaptability of the system is improved, but the control complexity increases due to threshold management and mode transition logic
Solution Approach 1:
The system dynamically switches between PTM and PTP transmission modes based on real-time subscriber count thresholds. When subscriber count exceeds the upper threshold, the system transitions from PTM to PTP mode; when it falls below the lower threshold, it switches back to PTM mode. This dynamic adaptation optimizes resource utilization and reliability based on current network conditions.
Solution Approach 2:
The system changes operational parameters (transmission mode) based on subscriber count parameters. By monitoring subscriber count and comparing against predefined thresholds, the system adjusts its transmission strategy, switching between PTM and PTP modes to optimize performance for different network conditions.
Data Source
AI summary
Apparatus and methods are provided for reliable multicast transmission with compact protocol stack. In one novel aspect, compact protocol stacks are configured for the UE and the base station handling both the PTM RB and the PTP RB. The compact protocol stack is either configured a compact RLC entity or a compact PDCP entity. The UE monitors a PTM LCH and a PTP LCH and sends feedback to the network with the PTP RB. The base station transmits MBS data packets in the PTM mode to the one or more subscriber UE, monitors feedback report from each subscriber UEs through corresponding PTP RB, and retransmits MBS data packets to one or more UEs through corresponding PTP RBs based on corresponding feedback reports. PTM-to-PTP and PTP-to-PTM mode switches are performed when triggering events are detected. The mode switch notification is sent to UEs via MAC CE or RLC control PDU.