DRX Handling in LTE License Assisted Access
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Solution Overview
Problem
LTE devices face challenges in efficiently operating on unlicensed carriers due to regulatory requirements and the need to coexist with other wireless systems like Wi-Fi, leading to issues with discontinuous transmission and clear channel assessment, which affect power consumption and data transmission reliability.
Innovation Solution
The method involves extending the active time during discontinuous reception (DRX) in LTE communications by monitoring the unlicensed carrier for occupancy and adjusting the transmission schedule based on clear channel assessment (CCA) results, allowing for extended data packet transmission when the carrier is available, and using different CCA thresholds for the UE and eNB to manage channel occupancy effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LTE devices perform clear channel assessment and follow discontinuous transmission requirements on unlicensed carriers, then coexistence with other wireless systems is improved, but transmission reliability and power consumption are worsened
Solution Approach 1:
The patent applies preliminary action by having the UE perform clear channel assessment (CCA) before entering DRX inactive period and before attempting transmission during active time. The UE proactively checks channel occupancy and prepares transmission buffers in advance, ensuring reliable transmission opportunities are captured when the channel becomes available, thus resolving the contradiction between coexistence requirements and transmission reliability.
Solution Approach 2:
The patent implements feedback mechanisms where the UE monitors channel occupancy conditions continuously and adjusts its transmission behavior based on real-time channel status. The UE receives feedback from the eNB regarding DRX configuration and channel conditions, and dynamically adapts its CCA performance and transmission timing, ensuring both coexistence with other systems and maintained transmission reliability.
2Productivity
If LTE devices extend active time during DRX to accommodate LBT procedures, then transmission opportunities are improved, but power consumption is worsened
Solution Approach 1:
The patent applies dynamics by making the DRX active time duration flexible rather than fixed. The UE dynamically adjusts its active time based on the outcome of LBT procedures and channel occupancy conditions. When LBT succeeds early, the UE can shorten its active time and enter inactive period sooner, saving power. When LBT takes longer, the UE extends active time to capture transmission opportunities, thus resolving the contradiction between productivity and power consumption.
Solution Approach 2:
The patent changes the parameter of active time duration based on channel conditions and LBT outcomes. The UE modifies its DRX behavior by adjusting the length of active periods according to measured channel occupancy and successful LBT completion times, optimizing the balance between transmission opportunities and power consumption through parameter adaptation.
3Productivity
If LTE devices use different CCA thresholds for UE and eNB, then channel occupancy management is improved, but device complexity is worsened
Solution Approach 1:
The patent applies local quality by assigning different CCA thresholds to different devices (UE and eNB) based on their specific roles and channel conditions. The eNB uses one threshold while the UE uses another, allowing each device to optimize its channel access behavior for its local context. This resolves the contradiction by improving channel occupancy management through localized threshold selection while managing device complexity through role-based threshold assignment.
Data Source
AI summary
An indication of a first energy detection threshold for a first clear channel assessment (CCA) can be received at a mobile device from a cell operating on an unlicensed carrier. The first energy detection threshold can be different than a second energy detection threshold for a second CCA at a network entity of the cell. A determination can be made as to whether the unlicensed carrier is occupied based upon the first CCA and the received first energy detection threshold. A data packet can be communicated between the mobile device and the cell when the unlicensed carrier is not otherwise occupied.