Shortened TTI Indexing for Latency Reduction in LTE
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Solution Overview
Problem
Current wireless communication systems, particularly LTE, face challenges in reducing packet data latency due to the inefficiencies in Transmission Time Interval (TTI) management, which affects user experience and throughput.
Innovation Solution
The implementation of shortened TTI (sTTI) techniques, including subframe-pairing-based indexing, bundling-window-based scheduling, and dynamic HARQ-ACK timeline design, to optimize control channel overhead and resource allocation, allowing for flexible scheduling and reduced latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional TTI management is used in LTE, then system stability is maintained, but packet data latency increases
Solution Approach 1:
The patent segments the TTI management into multiple components: subframe-pairing-based indexing for time organization, bundling-window-based scheduling for resource grouping, and dynamic HARQ-ACK timeline design for feedback management. This segmentation allows each component to be optimized independently, reducing overall latency while maintaining system stability.
Solution Approach 2:
The patent implements dynamic HARQ-ACK timeline design that adapts to varying transport block sizes and channel conditions. The system dynamically adjusts the timing of HARQ-ACK feedback based on real-time requirements, enabling flexible scheduling that reduces packet data latency while maintaining reliability under different operating conditions.
2Loss of time
If shortened TTI techniques are implemented, then packet data latency is reduced, but control channel overhead increases
Solution Approach 1:
The patent merges multiple control functions into bundled scheduling windows, where multiple sTTI scheduling decisions are made together rather than individually. This combining approach reduces the repetitive control signaling overhead while maintaining the low-latency benefits of shortened TTIs through efficient resource allocation across multiple time units.
Solution Approach 2:
The patent employs periodic bundling windows for scheduling multiple sTTI, creating a rhythm of control signaling that reduces overhead compared to continuous individual scheduling. The periodic structure allows the system to maintain updated scheduling information while reducing the frequency of control channel transmissions, thereby lowering overhead.
3Adaptability or versatility
If flexible scheduling is introduced to reduce latency, then system adaptability improves, but device complexity increases
Solution Approach 1:
The patent applies local quality optimization by implementing subframe-pairing-based indexing that organizes sTTI in a structured manner. This local organization provides flexibility for scheduling decisions within the paired subframe structure while maintaining overall system order, reducing the processing complexity associated with fully flexible scheduling.
Solution Approach 2:
The patent performs preliminary actions by pre-configuring bundling windows and subframe pairs before data transmission. This advance organization of time resources and scheduling structures enables flexible adaptation to varying traffic conditions while reducing real-time processing complexity, as the framework is established beforehand.
Data Source
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AI summary
Techniques discussed herein can be employed to facilitate communication via sTTIs (shortened Transmission Time Intervals). In one example embodiment, a UE (User Equipment) can comprise processing circuitry configured to: index a plurality of DL (Downlink) sTTIs of a DL subframe based at least in part on lengths of the plurality of DL sTTIs; decode a first DCI (Downlink Control Information) message from the DL subframe; and determine, based on the first DCI message, at least one of one or more DL sTTIs of the plurality of DL sTTIs that are associated with sPDSCH (sTTI Physical Downlink Shared Channel), or one or more UL (Uplink) sTTIs of a plurality of UL sTTIs of an associated UL subframe that are associated with sPUSCH (sTTI Physical Uplink Shared Channel).