Source eNB Downlink Data Forwarding for Handover Interruption
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Solution Overview
Problem
In cellular networks, particularly in 3GPP LTE networks, the handover process between cells results in data service interruption for user equipment (UE) as the source eNB stops transmitting data during the handover, leading to degraded user experience and packet loss.
Innovation Solution
The solution involves an apparatus with logic in the evolved node B (eNB) that continues to forward downlink data to the UE after initiating a handover command and terminates data transmission only upon detecting specific stop events, such as sequence number status transfer or successful UE access to the target eNB, thereby reducing or eliminating data interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the source eNB stops transmitting data to the UE during handover to manage the HO process, then the handover management is ensured, but data service interruption occurs degrading user experience
Solution Approach 1:
The source eNB forwards downlink data to the target eNB before the handover is complete and before the UE actually switches to the target eNB. This preliminary data forwarding ensures that data is already available at the target eNB when the UE connects, eliminating the need to stop data transmission during handover while still managing the handover process properly
Solution Approach 2:
The target eNB acts as an intermediary by receiving downlink data from the source eNB during the handover process and holding it until the UE successfully connects. This intermediary role allows continuous data flow through the network while the UE transitions between cells, preventing data interruption at the UE side
2Reliability
If the source eNB stops transmitting data during handover, then the handover process can be managed properly, but packet loss occurs
Solution Approach 1:
Data is forwarded to the target eNB in advance during the handover preparation phase, so when the UE successfully hands over and connects to the target eNB, the data is already there and can be transmitted immediately without loss. This eliminates the gap where packets would otherwise be lost during the handover execution phase
Solution Approach 2:
The downlink data transmission is maintained continuously by forwarding data from the source eNB to the target eNB during handover, ensuring that the data flow never stops. The target eNB holds the forwarded data and transmits it to the UE after connection, maintaining continuous useful action throughout the handover process
Data Source
AI summary
User equipment (UE) handover (HO) techniques for reducing or eliminating interruption time during an HO process are described. In one embodiment, for example, an apparatus may include at least one memory and logic for an evolved node B (eNB), at least a portion of the logic comprised in hardware coupled to the at least one memory. The logic may be operative to forward downlink (DL) data received from a serving gateway (SGW) to user equipment (UE), transmit a handover command to the UE to trigger execution of a handover (HO) process to handover the UE to a target eNB, continue forwarding at least a portion of the DL data to the UE following transmission of the handover command, and terminate transmission of the DL data to the UE responsive to detecting a stop DL data event. Other embodiments are described and claimed.