UL DMRS Transmission Location Determination in LTE Short TTI
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Solution Overview
Problem
The existing LTE system lacks a DMRS scheme for short TTI transmission, leading to excessive DMRS overhead and suboptimal demodulation performance due to the absence of dynamic determination of UL DMRS transmission locations.
Innovation Solution
The method dynamically determines the transmission locations of UL DMRS based on the DL control channel, allowing for reduced DMRS overhead and improved demodulation performance by scheduling DMRS in conjunction with sPUSCH and sPUCCH transmissions, using predefined timing offsets and patterns indicated by the DL control channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If each short TTI includes the DMRS, then the demodulation performance is improved, but the DMRS overhead becomes too much
Solution Approach 1:
The patent combines multiple short TTIs into a single TTI for DMRS transmission. Specifically, multiple short TTIs (e.g., 2, 3, 4, or 7 symbols) are grouped together and share a common DMRS transmitted at the beginning of the combined TTI, rather than each short TTI having its own separate DMRS. This merging approach maintains demodulation capability while significantly reducing the total number of DMRS transmissions required.
Solution Approach 2:
The DMRS transmitted for a combined TTI serves multiple short TTIs simultaneously. A single DMRS transmission provides reference signals for channel estimation across multiple short TTIs, making the DMRS multi-functional. This universal approach allows one DMRS to support demodulation for several short TTIs, reducing overall overhead while maintaining performance.
2Stability of the object's composition
If the DMRS scheme is defined in units of sub-frame, then the existing LTE structure is maintained, but it is incompatible with short TTI transmission requirements
Solution Approach 1:
The patent segments the sub-frame into multiple short TTIs, each consisting of a small number of symbols (2, 3, 4, or 7 symbols). Within each sub-frame, multiple short TTIs can be scheduled for different terminals or purposes. This segmentation allows the system to maintain the sub-frame structure while enabling flexible short TTI transmissions by defining DMRS at the short TTI level rather than requiring separate DMRS for each symbol or mini-slot.
Solution Approach 2:
The patent introduces dynamic TTI length configuration where the length of short TTIs can be flexibly adjusted (2, 3, 4, or 7 symbols) based on transmission requirements. The DMRS positioning and combining strategy adapts dynamically to the configured short TTI lengths, allowing the system to optimize between latency, overhead, and performance depending on the specific short TTI configuration being used.
Data Source
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AI summary
Embodiments of the present disclosure provide methods and devices for dynamically determining a transmission location of an UpLink (UL) DeModulation Reference Signal (DMRS), including: receiving, by a terminal, a DownLink (DL) control channel; and determining, by the terminal, the transmission location of the UL DMRS according to the DL control channel.