Conditional Handover Bicasting for Wireless Mobility
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Solution Overview
Problem
Existing mobility techniques in wireless communication networks, such as handovers, face challenges in robustness, especially for data-intensive and delay-sensitive applications like video streaming, due to issues with HO command segmentation and retransmission, leading to potential failures and service degradation.
Innovation Solution
The implementation of bicasting mechanisms, where a target node determines the suitability of handover based on UE characteristics like buffer status, data rate, and QoS class, and selects appropriate bicasting modes to ensure seamless data transfer during handovers, using either source node or core network bicasting, optimizing buffer resources and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If handover command segmentation and retransmission are used to ensure reliable delivery, then reliability of handover is improved, but handover latency and complexity increase
Solution Approach 1:
The target base station prepares and buffers data proactively before the handover is executed. By pre-positioning data at the target node and establishing data forwarding paths in advance, the system eliminates the need for post-handover data retransmission and segmentation, thereby reducing handover latency while maintaining reliability
Solution Approach 2:
The source base station acts as an intermediary by forwarding data to the target base station during the handover process. This data forwarding mechanism ensures continuous data delivery without requiring the UE to retransmit or wait for segmented commands, resolving the contradiction between reliability and latency
2Reliability
If bicasting is activated for all UEs during handover, then mobility robustness is improved, but network resource consumption increases
Solution Approach 1:
Bicasting is selectively applied based on local conditions - specifically, only UEs with active data connections are subjected to bicasting during handover. The network evaluates each UE's data activity status and applies bicasting only where necessary, rather than uniformly to all UEs, thereby maintaining mobility robustness for active users while conserving network resources for inactive users
Solution Approach 2:
The system dynamically changes the bicasting parameter based on UE data connection status. When a UE has an active data connection, bicasting is enabled; when inactive, it is disabled. This parameter adjustment resolves the contradiction by adapting resource allocation to actual service requirements
3Reliability
If buffer space is allocated at target node for all handovers, then data transfer reliability is improved, but device complexity and resource allocation overhead increase
Solution Approach 1:
The target base station pre-allocates buffer space specifically for UEs that are undergoing or about to undergo handover. By preparing buffers in advance for identified handover candidates rather than maintaining general-purpose buffers, the system ensures data transfer reliability while minimizing the complexity of buffer management through targeted, condition-based allocation
Data Source
AI summary
Embodiments include methods performed by a network node, in a radio access network, RAN, that is a target node candidate for a mobility operation of a user equipment, UE. Such methods include receiving, from a source node serving the UE, a request to prepare a mobility procedure for the UE in relation to a candidate target cell associated with the network node. The request can include characteristics associated with a data connection of the UE. Such methods include determining that the UE can be admitted for the requested mobility procedure based on the characteristics, and determining to activate bicasting of the data connection. Different bicasting modes can be selected. Such methods also include transmitting, to the source node, a response that includes a bicasting configuration associated with the UE. Other embodiments include complementary methods performed by source nodes, as well as network nodes configured to perform such methods.