MAC-hs Reordering Queue Flush for Inter-RAT Handover
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inter-RAT handovers, particularly from 3G RATs like UMTS with HSDPA to 2G RATs like GSM, result in data loss and delay due to the reordering techniques used in the MAC-hs entity, as the protocol stack is not in the correct state to handle data during the transition.
Innovation Solution
Flush all correctly received data from the reordering queue to a higher layer and stop the associated timer before initiating the handover, ensuring that the first protocol stack remains in a correct state for processing, thus avoiding data loss and delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reordering techniques are used in the MAC-hs entity during HSDPA operation, then data throughput and reliability are improved, but data loss and delay occur during inter-RAT handovers to 2G RATs
Solution Approach 1:
The patent applies preliminary action by flushing the reordering queue and stopping the reordering timer before initiating the handover procedure. This prepares the MAC-hs entity in advance for the transition to 2G RAT, ensuring that no data is lost during the handover process while maintaining the reliability benefits of reordering techniques during normal HSDPA operation.
2Productivity
If reordering techniques are used in the MAC-hs entity, then data processing efficiency is improved, but protocol stack complexity increases during transition
Solution Approach 1:
The patent simplifies the protocol stack transition by performing preliminary actions (flushing reordering queue, stopping timer) before handover. This ensures the MAC-hs entity is in a known clean state during transition, reducing complexity in handling protocol stack reconfiguration while maintaining data processing efficiency during normal operation.
3Speed
If handover is initiated without flushing reordering queue, then handover speed is improved, but data loss occurs
Solution Approach 1:
The patent achieves a balance between handover speed and data integrity by implementing preliminary flushing of the reordering queue and stopping the reordering timer before handover initiation. This preliminary preparation ensures data is not lost during the transition while minimizing the impact on handover speed by performing the flushing operation as part of the standard handover procedure.
Data Source
AI summary
A method in a wireless communications device having a first protocol stack for use with a first radio access technology (RAT) and a second protocol stack for use with a second RAT, the first protocol stack comprising a reordering component associated with a first layer of the first protocol stack and arranged to implement a data reordering queue, the method for transitioning from the first RAT to the second RAT, the method comprising: determining that the device should transition from the first RAT to the second RAT; in response to determining that the device should transition, determining that data is present in a reordering queue implemented by the reordering component; sending the data present in the reordering queue to a second layer which is higher than the first layer; and attempting transitioning from the first RAT to the second RAT.