Relay Apparatus RLC Entity Acknowledgment Delay
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Solution Overview
Problem
In mobile communication systems, existing relay apparatuses face challenges in dynamically managing radio resources and switching data transfer paths between user equipment and base stations, particularly in maintaining reliable data transmission during radio condition deterioration or topology changes.
Innovation Solution
A relay apparatus with reception and transmission side RLC entities that delay acknowledgments and manage data buffering to ensure successful data transfer, using an upper entity to provide held data to alternative transmission paths when radio conditions deteriorate or data transfer paths need switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the relay apparatus transmits data immediately after receiving it without waiting for acknowledgments, then the data transmission speed is improved, but the reliability of data transmission deteriorates because the relay cannot confirm successful delivery to the upper node
Solution Approach 1:
The relay apparatus performs preliminary actions by receiving and buffering data from the lower node before the upper node actually needs it. The RLC entity stores data in advance and transmits it to the upper node when ready, rather than waiting for requests or acknowledgments. This preliminary buffering action enables both fast transmission (when buffer is ready) and reliable delivery (by confirming upper node receipt before lower node acknowledges).
Solution Approach 2:
The relay apparatus acts as an intermediary between the lower node and upper node, with the RLC entity serving as the mediating buffer. The intermediary holds data temporarily and manages the timing of transmissions to different nodes independently, allowing the lower node to send data quickly while the upper node receives it reliably at appropriate times.
2Device complexity
If the relay apparatus uses a single data transfer path, then the device complexity is reduced, but the adaptability to radio condition changes deteriorates
Solution Approach 1:
The relay apparatus implements dynamic path selection by monitoring radio conditions between the upper node and second lower node, and switching data transfer paths based on current conditions. The system transitions from static single-path to dynamic multi-path operation, where the RLC entity can route data through different lower nodes depending on which path offers better radio conditions at any given time.
Solution Approach 2:
The system changes the operational parameter of data transfer path selection based on radio condition parameters. When radio conditions deteriorate on one path, the system changes to an alternative path, adjusting the routing parameter dynamically according to measured radio quality parameters.
3Reliability
If the relay apparatus waits for acknowledgments before confirming data receipt to the sending node, then the reliability of data transmission is improved, but the loss of time increases due to waiting delays
Solution Approach 1:
The relay apparatus performs preliminary acknowledgment by confirming data receipt to the lower node based on receiving an acknowledgment from the upper node, rather than waiting for the lower node to timeout. The RLC entity proactively sends acknowledgments upstream when data is successfully transmitted to the upper node, eliminating unnecessary waiting time while maintaining reliability.
Solution Approach 2:
The system implements feedback mechanisms where acknowledgment information flows bidirectionally: from upper node to relay (confirming successful reception), and from relay to lower node (confirming successful forwarding). This feedback loop enables the relay to inform the lower node immediately when data is successfully delivered upstream, reducing time loss while ensuring reliable transmission.
Data Source
AI summary
A relay apparatus according to an embodiment is for use in a mobile communication system. The relay apparatus comprises: a reception side RLC entity configured to receive data from a first communication apparatus; and a transmission side RLC entity configured to transmit, to a second communication apparatus, the data received by the reception side RLC entity. The transmission side RLC entity is configured to receive, from the second communication apparatus, a first acknowledgement indicating that the second communication apparatus has successfully received the transmitted data. The reception side RLC entity is configured to transmit, to the first communication apparatus, a second acknowledgement indicating that the reception side RLC entity has successfully received the data after waiting until the transmission side RLC entity receives the first acknowledgement.