Wireless Multicast Flow Control via PDCP Feedback
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Solution Overview
Problem
Current multicast transmission in wireless communication systems faces inefficiencies in resource utilization and increased delay due to the lack of effective flow control mechanisms, particularly when transitioning between different transmission modes.
Innovation Solution
The method involves a node in a wireless communication system receiving and transmitting downlink user data with PDCP sequence number information to manage flow control, including the highest sequence number successfully delivered in sequence and transmitted to lower layers, enabling efficient data delivery and reducing overhead and delay by adjusting data transmission based on buffer size and transmission mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multicast transmission is performed without flow control mechanisms, then data transmission can proceed continuously, but resource utilization deteriorates and transmission delay increases
Solution Approach 1:
The patent implements flow control by introducing feedback mechanisms where the receiving node sends acknowledgments and status information back to the transmitting node. This feedback enables the transmitting node to adjust its transmission rate and buffer management, resolving the contradiction between continuous transmission and resource utilization by making transmission adaptive to actual network conditions.
Solution Approach 2:
The patent applies dynamic buffer size adjustment and adaptive transmission rate modification based on network conditions. The buffer size and transmission parameters are not fixed but dynamically adjusted according to feedback from the receiving node, allowing the system to maintain continuous transmission while optimizing resource utilization under varying load conditions.
2Productivity
If multicast transmission is performed without flow control mechanisms, then data can be transmitted without interruption, but transmission delay increases
Solution Approach 1:
The receiving node provides feedback information including acknowledgment status and buffer state to the transmitting node. This feedback enables the transmitting node to detect transmission issues early and adjust timing, reducing delays while maintaining continuous transmission flow through adaptive retransmission and rate adjustment.
Solution Approach 2:
The patent implements preliminary buffer management where data is pre-buffered and transmission parameters are pre-configured based on expected network conditions. This preliminary preparation reduces actual transmission delays by having data ready and transmission parameters optimized before actual data flow begins.
3Loss of energy
If flow control is implemented in multicast transmission, then resource utilization and delay are improved, but system complexity increases
Solution Approach 1:
The patent designs flow control mechanisms that operate across multiple transmission modes (unicast and multicast) using a unified framework. The same basic flow control principles and message structures are applied universally, reducing the need for mode-specific complex logic and simplifying the overall system while maintaining resource utilization benefits.
Solution Approach 2:
The patent implements flow control by changing transmission parameters (rate, buffer size, timing) rather than introducing fundamentally new complex mechanisms. These parameter adjustments are made based on feedback and can be implemented through existing protocol frameworks, reducing complexity compared to designing entirely new flow control systems.
4Adaptability or versatility
If transmission mode conversion is performed without flow control, then mode switching is flexible, but data loss and delay occur
Solution Approach 1:
The patent uses feedback information from the receiving node about current transmission status and buffer state to determine the optimal timing and conditions for mode conversion. This feedback-guided approach ensures that unicast-to-multicast or multicast-to-unicast transitions occur when they will not cause data loss, maintaining both flexibility and reliability.
Solution Approach 2:
The patent implements buffer management that prepares for potential mode conversions in advance. Data is buffered with sufficient headroom to accommodate transitions between transmission modes, ensuring that no data is lost during mode switching. This preliminary cushioning allows flexible mode changes while protecting data delivery reliability.
Data Source
AI summary
The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. A method performed by a first node in a wireless communication system, including receiving, from a second node, downlink user data through a first radio bearer, the downlink user data including multicast service data; transmitting, to at least one UE, the downlink user data through a second radio bearer; and transmitting, to the second node, a downlink data delivery status including PDCP sequence number information, wherein the PDCP sequence number information includes a higher PDCP sequence number between a highest PDCP sequence number successfully delivered in sequence associated with a first transmission mode and a highest PDCP sequence number transmitted to lower layers associated with a second transmission mode.