Mobile Station Packet Reordering During Handover

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Solution Overview

Problem

In LTE communication systems, handover processes lead to transmission interruptions and packet reordering issues, resulting in increased communication delays and reduced throughput due to the lack of clear notification about packet forwarding from the handover source base station to the target base station.

Innovation Solution

Implementing a method where the handover source base station notifies the mobile station about the execution of packet forwarding during handover, allowing the mobile station to determine whether reordering is necessary based on this information, and prioritizing packet transmission from the handover target base station to maintain sequence order.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the handover source base station transfers packets to the handover target base station during handover, then packet loss is prevented and transmission continuity is maintained, but the mobile station cannot determine whether reordering is necessary, leading to unnecessary reordering attempts and increased processing delay

Engineering Contradiction:
Improvepacket transmission continuityVSAvoidreordering processing delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The handover source base station sends notification information to the mobile station indicating whether packet transfer has been executed. This feedback mechanism allows the mobile station to make informed decisions about reordering operations, avoiding unnecessary processing when packets are not transferred, thus reducing delay while maintaining transmission reliability.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The mobile station autonomously determines whether to perform reordering based on the notification information received from the handover source base station. By using the notification to self-adjust its reordering behavior, the mobile station eliminates unnecessary processing steps while ensuring proper packet sequencing when needed.

Inventive Principle:
Principle #25Self-service

2Stability of the object's composition

If the mobile station performs reordering of received packets, then packet sequence order is maintained, but unnecessary reordering attempts increase processing complexity and delay when packets are not forwarded

Engineering Contradiction:
Improvepacket sequence orderVSAvoidreordering processing complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The notification information from the handover source base station serves as feedback that guides the mobile station's reordering decision. When the notification indicates no packet transfer, the mobile station skips reordering operations, thereby reducing processing complexity and avoiding unnecessary delays while maintaining sequence integrity when transfer occurs.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

Instead of always performing full reordering operations, the mobile station applies partial action by conditionally executing reordering only when the notification indicates packet transfer has occurred. This selective approach reduces overall processing complexity while ensuring packet sequence stability is maintained when necessary.

Inventive Principle:
Principle #16Partial or excessive action

3Productivity

If the handover source base station notifies the mobile station about packet forwarding execution, then unnecessary reordering is avoided and throughput is improved, but additional signaling is required during handover

Engineering Contradiction:
Improvesystem throughputVSAvoidhandover signaling complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The notification information regarding packet transfer execution is merged with existing handover signaling messages between the handover source base station and the mobile station. By combining this additional information with routine handover communications, the system improves throughput through optimized reordering decisions without significantly increasing overall signaling complexity.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP2129053B1Base station, mobile station, communication system and reordering method thereof
Publication Date: 2014.06.18 FUJITSU LTD
  • EP2129053B1 patent drawingFigure 1~2(d)
  • EP2129053B1 patent drawingFigure 3
  • EP2129053B1 patent drawingFigure 4

AI summary

Disclosed is a reordering method for sending packets, to which numbers indicating sequence are attached, from a base station to a mobile station, and rearranging the packets in order of the sequence number in the mobile station. When a handover source base station transfers packets which have not been sent to the mobile station, out of packets received from a host station, to a handover target base station, and the handover target base station sends the packets to the mobile station, data is sent from the handover source base station to the mobile station to notify that transference of the packets has been executed at the execution of handover sequence. The mobile station executed, reordering of the received packets when the transference of the packets has been executed.