RLC Entity Dual ACK Window Update and Retransmission Control
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Solution Overview
Problem
In cellular communication systems, especially in 5G networks with Integrated Access and Backhaul (IAB) nodes, there is a challenge in implementing end-to-end packet loss compensation due to multi-hop relay failures, where existing Automatic Repeat reQuest (ARQ) mechanisms struggle to compensate for packet loss effectively across multiple hops, leading to inefficiencies in data transmission and retransmission processes.
Innovation Solution
The introduction of a communication control method that utilizes two types of acknowledgments (ACKs) - a first ACK for transmission window update and a second ACK for retransmission control - allows for efficient packet loss compensation by separating the timing of window updates and retransmission decisions, thereby improving data reliability across multiple hops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing ARQ mechanisms are used in multi-hop relay networks, then packet loss compensation is attempted, but the compensation effectiveness deteriorates due to multi-hop relay failures and transmission inefficiencies
Solution Approach 1:
The patent segments the acknowledgment process into two distinct types: first acknowledgments for transmission window updates and second acknowledgments for retransmission control decisions. This segmentation allows the system to separately optimize window management and retransmission timing, improving both reliability of packet loss compensation and productivity of data transmission by avoiding the inefficiencies of unified ARQ mechanisms in multi-hop networks
Solution Approach 2:
The patent changes the parameter of acknowledgment timing and function by introducing dual ACK types with different purposes. First ACKs trigger window updates immediately upon receipt, while second ACKs are used specifically for retransmission decisions. This parameter change resolves the contradiction by enabling efficient window management without compromising retransmission reliability, thereby improving both packet loss compensation effectiveness and data transmission efficiency
2Speed
If transmission window updates are performed frequently, then data transmission speed is improved, but packet loss reliability deteriorates due to unstable backhaul links
Solution Approach 1:
By segmenting acknowledgments into first ACKs (for window updates) and second ACKs (for retransmission control), the patent enables frequent window updates via first ACKs without compromising retransmission reliability. The transmission window can be updated promptly upon receiving first ACKs, maintaining high transmission speed, while retransmission decisions are made based on separate second ACKs, ensuring reliability even over unstable backhaul links
Solution Approach 2:
The patent performs preliminary window updates based on first acknowledgments before final retransmission decisions are made using second acknowledgments. This preliminary action allows the transmission window to advance and maintain high data transmission speed, while the subsequent retransmission control based on second ACKs ensures that packet loss compensation remains reliable despite the aggressive window update strategy
3Reliability
If retransmission control is tightened to improve packet loss compensation, then data reliability is improved, but transmission efficiency deteriorates due to excessive retransmissions
Solution Approach 1:
The patent segments retransmission control into a separate second acknowledgment process, distinct from the first acknowledgments used for window updates. This segmentation allows tight retransmission control to be applied selectively based on second ACKs, improving data reliability without causing excessive retransmissions that would harm transmission efficiency. The separated control mechanism enables precise management of retransmission triggers
Solution Approach 2:
The patent implements a feedback mechanism where second acknowledgments provide explicit information about packet delivery status to trigger retransmission decisions. This feedback-based approach ensures that retransmissions are performed only when necessary, improving data reliability through controlled retransmission while avoiding the transmission efficiency loss that would result from excessive or unnecessary retransmissions
Data Source
AI summary
A communication control method includes by a Radio Link Control (RLC) entity of a communication apparatus being either of a user equipment or a relay node, transmitting a data packet to a parent node and then receiving a first acknowledgment corresponding to the data packet from the parent node, by the RLC entity, updating a transmission window managed at the RLC entity in response to the receiving the first acknowledgment, and by the communication apparatus, controlling, in response to receiving a second acknowledgment corresponding to the data packet from the parent node after the receiving the first acknowledgment, retransmission related to the data packet based on the second acknowledgment.