Lossless Data Delivery in IAB Multi-Hop Relay Networks
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Solution Overview
Problem
In Integrated Access and Backhaul (IAB) multiple hop relay networks, dynamic route changes can lead to data loss due to link failures, as acknowledged communications are dropped without recovery, especially when channel or network conditions deteriorate, causing a failure in the relay hop.
Innovation Solution
The last unchanged node in a multi-hop route preserves unacknowledged and unsent PDCP PDUs from the protocol stack of the failed relay hop and populates the new route's protocol stack with this data, ensuring data recovery by transmitting the copied PDUs before new data is received, and pre-emptively detects link failures to trigger route changes before they deteriorate further.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dynamic route changes are implemented in IAB networks to adapt to channel conditions, then network adaptability is improved, but data loss occurs during route changes
Solution Approach 1:
The patent applies preliminary action by having the last unchanged node preserve unacknowledged and unsent PDCP PDUs from the failed route before the route change is fully executed. This pre-preservation of data ensures that when the route changes dynamically, no data is lost because the data is already safeguarded and will be transmitted through the new route.
Solution Approach 2:
The patent implements copying by creating a copy of the unacknowledged and unsent PDCP PDUs at the last unchanged node. This copy is then transmitted through the new route, ensuring data recovery and lossless delivery even though the original route has failed. The copying mechanism allows the system to maintain data integrity during dynamic route changes.
2Reliability
If route changes are triggered preemptively to prevent link failure, then reliability is improved, but data loss may occur during the transition
Solution Approach 1:
The patent applies preliminary action by preserving data at the last unchanged node before the route change is fully executed. This ensures that even when route changes are triggered preemptively, the data is already safeguarded and will be transmitted through the new route without loss.
Solution Approach 2:
The patent implements feedback by monitoring the status of the old route and using this information to control the transmission of preserved data through the new route. When the old route fails or is replaced, the system detects this change and activates the preserved data transmission, ensuring seamless transition and data integrity.
3Reliability
If data is preserved and retransmitted through new route, then data recovery is achieved, but transmission time increases
Solution Approach 1:
The patent applies preliminary action by preserving data in advance at the last unchanged node, so that when a route failure occurs, the data is already ready for immediate retransmission through the new route. This eliminates the need for retransmission requests and waiting, significantly reducing the time penalty despite the additional transmission path.
Solution Approach 2:
The patent implements skipping by directly transmitting the preserved data through the new route without going through the normal acknowledgment and retransmission protocol. This rushes the data through the alternative path, minimizing the time loss associated with route changes.
Data Source
AI summary
The described technology is generally directed towards lossless delivery of data when there are route changes, e.g., in an integrated access and backhaul (IAB) multi-hop relay network. When a route changes is to occur, the last unchanged node in a multiple hop route preserves the data (e.g., copies unacknowledged and unsent PDCP PDUs from the protocol stack corresponding to the radio link control layer of the failed relay hop, and populates a replacement protocol stack for the node in the new route with the preserved data. Also described is pre-emptive detection of link failure, which triggers a route change based on monitoring retransmissions to detect a deteriorating link, which can occur before complete link communication failure.