5G-LTE Handover Reconfiguration for Near-Zero Mobility Latency
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Solution Overview
Problem
Handover latency in cellular networks, particularly in 5G systems, results in periods of poor quality service or loss of service due to the time-consuming processes involved in transitioning between different base stations, exceeding the desired latency threshold of 1 ms.
Innovation Solution
Minimizing physical layer and Layer 2 reconfiguration during handovers by sharing the same configuration between source and target base stations, avoiding explicit RRC reconfiguration, and optimizing handover processes to reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional handover procedures are performed between base stations, then mobility between cells is achieved, but handover latency increases to 30-50 ms causing service interruption
Solution Approach 1:
The UE is configured with multiple uplink carriers (primary uplink carrier and secondary uplink carriers) in advance before handover is needed. These carriers are pre-configured with their respective base stations, so when handover is required, the UE can immediately switch to a pre-configured secondary uplink carrier associated with the target base station, eliminating the need for time-consuming reconfiguration during handover.
Solution Approach 2:
The system dynamically selects which uplink carrier to use based on the current serving base station. The UE maintains multiple uplink carriers in a ready state and switches between them dynamically depending on which base station is currently serving the UE, enabling fast handover without service interruption.
2Loss of time
If multiple uplink carriers are configured and switched during handover, then handover latency is reduced to near zero, but device complexity increases
Solution Approach 1:
The UE maintains copies of uplink carrier configurations for multiple base stations simultaneously. Each secondary uplink carrier is pre-configured with the necessary parameters to communicate with a specific target base station, allowing the UE to have ready-to-use communication paths to multiple potential target base stations without needing to reconfigure during handover.
Data Source
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AI summary
User equipment (UE), an enhanced NodeB (eNB) and method of reducing handover latency are generally described. The UE may transmit measurement feedback to the eNB based on control signals. The UE may receive a reconfiguration message from the eNB or another eNB to the UE is attached. The reconfiguration message may contain reconfiguration information indicating whether or not a physical layer or layer 2 of the UE is to be reconfigured and/or a security key is to be updated. The reconfiguration information may be dependent on whether the handover is between eNBs controlled by a same entity and/or whether the handover comprises an intra-frequency transition. The UE or eNB may initiate handover of the UE. During handover the UE may avoid physical layer or layer 2 reconfiguration or the security key update. The security key and data for the UE may be provided directly between the eNBs.