Cross-TxOP UL Scheduling for LTE Unlicensed Spectrum
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Solution Overview
Problem
In 3GPP LTE systems, uplink (UL) performance in unlicensed spectrum is degraded due to listen-before-talk (LBT) procedures and the 4-subframe processing delay, limiting UL scheduling within a transmission opportunity (TxOP) and leading to UL starvation, especially when LTE coexists with non-scheduled systems like Wi-Fi.
Innovation Solution
Cross-TxOP UL scheduling allows UL subframes in one TxOP to be scheduled in preceding TxOPs, overcoming the delay limitation by enabling UL transmission to start earlier and increasing UL opportunities, applicable to MuLTEfire and eLAA technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If UL scheduling is limited within the same TxOP to meet processing delay requirements, then processing delay is satisfied, but UL throughput and spectral efficiency deteriorate
Solution Approach 1:
The patent applies preliminary action by performing UL scheduling in a first TxOP that occurs before the actual UL transmission in a second TxOP. This allows the scheduling decision to be made in advance, satisfying processing delay requirements while enabling the UL transmission to occur in a subsequent TxOP when channel conditions may be more favorable, thereby improving overall UL throughput and spectral efficiency.
2Adaptability or versatility
If LBT procedures are performed in unlicensed spectrum, then coexistence with Wi-Fi is enabled, but UL performance and scheduling opportunities deteriorate
Solution Approach 1:
The patent segments the scheduling and transmission processes into separate TxOPs. The first TxOP is used for LBT procedures and scheduling decisions, while the second TxOP is used for actual UL transmission. This segmentation allows the system to perform necessary LBT procedures for coexistence while creating dedicated transmission opportunities that improve UL performance by decoupling the scheduling decision from the transmission execution.
3Adaptability or versatility
If TxOP duration is shortened to enable frequent scheduling, then scheduling flexibility is improved, but UL transmission opportunities and spectral efficiency deteriorate
Solution Approach 1:
The patent introduces a temporal dimension by allowing scheduling decisions to span across multiple TxOPs. Instead of confining scheduling to within a single TxOP, the system schedules in the first TxOP and executes transmission in a subsequent second TxOP. This dimensional extension resolves the contradiction by maintaining scheduling flexibility through frequent short TxOPs while improving spectral efficiency by enabling transmissions in dedicated subsequent opportunities.
Data Source
AI summary
Technology for a user equipment (UE) operable to process scheduled uplink (UL) transmissions is disclosed. The UE can process one or more uplink (UL) grants received from an eNodeB on a downlink (DL) subframe in a first transmission opportunity (TxOP). The UE can determine, based on the one or more UL grants, one or more UL subframes in at least one subsequent TxOP for an UL transmission from the UE. The UE can process the UL transmission for communication on the one or more UL subframes in the at least one subsequent TxOP.