Handover Notification Mechanism for Reducing Packet Retransmission
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Solution Overview
Problem
In wireless communications, especially during user equipment (UE) handovers, excessive packet retransmissions occur due to handover durations exceeding round trip times, leading to increased latency and congestion, as traffic sources retransmit packets that expire during the handover process.
Innovation Solution
A method is implemented to reduce retransmissions by generating and transmitting handover start and completion notifications to traffic sources, indicating an outage time window, which allows traffic sources to pause and resume packet transmission accordingly, preventing unnecessary retransmissions and maintaining ultra-low latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If handover duration is extended to ensure reliable packet delivery during mobility, then packet loss is reduced, but latency increases and retransmissions occur
Solution Approach 1:
The network exposes handover start and completion events to the traffic source in advance, allowing the traffic source to proactively pause packet transmission before the handover completes and resume immediately after. This preliminary awareness prevents the traffic source from sending packets during the outage window, eliminating retransmissions without extending handover duration.
Solution Approach 2:
The system implements a feedback mechanism where the network continuously monitors handover status and provides real-time notifications to the traffic source. This feedback loop enables the traffic source to adapt its transmission behavior dynamically, pausing during handover and resuming when complete, thereby maintaining reliability while minimizing latency.
2Loss of time
If retransmission timeout period is reduced to achieve low latency, then response time improves, but packet retransmissions increase during handover
Solution Approach 1:
By providing handover event notifications in advance, the system allows the traffic source to pause transmission before the handover completes. This prevents packets from being sent during the outage window, so even with a reduced timeout period, retransmissions are avoided because packets are not transmitted during the handover period in the first place.
Solution Approach 2:
The traffic source takes preliminary anti-action by pausing packet transmission upon receiving handover start notification. This preemptive pause counteracts the potential harm of reduced timeout periods that would otherwise cause retransmissions, ensuring packets are not sent when the network is in an unstable handover state.
3Productivity
If traffic source continuously transmits packets to maintain high data rate, then throughput is maximized, but retransmissions increase during handover causing congestion
Solution Approach 1:
The system dynamically adjusts the traffic source's transmission rate based on real-time handover status. During normal operation, the traffic source transmits at high rate to maximize throughput. Upon receiving handover start notification, the traffic source dynamically pauses transmission, then resumes at full rate after handover completion. This dynamic adaptation maintains high productivity while preventing congestion during handover.
Solution Approach 2:
The feedback mechanism provides continuous handover status information to the traffic source, enabling real-time adjustment of transmission behavior. This feedback loop ensures the traffic source can maintain high data rates during stable periods while automatically reducing transmission during handover, thereby balancing productivity with network congestion control.
Data Source
AI summary
Interruptions in communication due to user equipment (UE) handovers (HO) are signaled from the mobile communication network to the traffic source. For ultra-low latency and reliable communication, the signaling of HO start and completion notifications prevents retransmissions of in-flight packets by the traffic source, eliminating additional delays and inefficiencies. Signaling can be implemented by a network element, by a network element in conjunction with a smart traffic handler between the network and the traffic source (e.g., applications) and by a UE having at least two different radio interfaces.