Sidelink-Assisted Handover for Cellular Network Latency Reduction
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Solution Overview
Problem
Current cellular networks face significant latency and service disruptions during UE handovers due to timing synchronization issues between source and target network apparatuses, especially in frequency division duplex systems, leading to unacceptable delays and failures in providing ultra-reliable low-latency communication (URLLC) services.
Innovation Solution
The proposed solution involves using a sidelink channel for UE-to-Ue communication to assist handovers by relaying timing and link state information between network apparatuses, allowing UEs to synchronize with the target network timing before attaching, thereby reducing latency and maintaining connectivity even when out of coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional handover procedures are used in cellular networks, then network infrastructure can manage UE connections, but handover latency increases and service disruptions occur due to timing synchronization issues between source and target network apparatuses
Solution Approach 1:
The patent applies preliminary action by having the UE perform timing synchronization with the target network apparatus before the actual handover occurs. The UE receives timing synchronization information from the target network apparatus while still connected to the source network apparatus, and applies this synchronization information during the handover process. This preliminary synchronization eliminates timing misalignment issues that would otherwise cause handover failures and service disruptions, thereby improving handover reliability without increasing latency.
2Measurement precision
If timing synchronization is performed during handover between source and target network apparatuses, then synchronization accuracy can be maintained, but handover latency increases due to the time required for synchronization procedures
Solution Approach 1:
The patent resolves this contradiction by performing timing synchronization in advance, before the handover is triggered. The UE receives timing synchronization information from the target network apparatus during the connection to the source network apparatus, so that when handover occurs, the synchronization is already established. This eliminates the need for time-consuming synchronization procedures during handover, maintaining synchronization accuracy while minimizing handover latency.
3Adaptability or versatility
If UEs communicate directly over sidelink channels, then connectivity can be maintained for high mobility UEs, but timing synchronization becomes more difficult and service reliability decreases
Solution Approach 1:
The patent applies the intermediary principle by using the network apparatuses (source and target base stations) as mediators to provide timing synchronization information to the UE. Even though the UE communicates directly with other UEs over sidelink channels, the network apparatuses act as intermediaries that supply reference timing information. This allows the UE to maintain accurate timing synchronization while supporting high mobility scenarios, thereby preserving service reliability without limiting adaptability.
Data Source
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AI summary
A first user equipment, UE, apparatus comprising a processor adapted to execute the following operations to assist a handover of a second UE from a source network apparatus to a target network apparatus: maintain a sidelink connection with the second UE, maintain and/or establish a cellular connection, in particular with the target network apparatus, report to the target network apparatus a link state information, based on the link state information received from the second UE through the sidelink connection, receive from the target network apparatus a first control information calculated based on the link state information and send to the second UE through the sidelink connection a second control information, based on the first control information, to assist the handover of the second UE to the target network apparatus.