DMRS Pilot Sharing for Shortened Transmission Time Intervals
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing reference signal patterns and pilot sharing for shortened transmission time intervals (sTTIs), particularly in low latency communications, where traditional methods struggle to optimize resource allocation and channel estimation due to reduced TTI lengths.
Innovation Solution
The proposed solution involves a method where base stations allocate and share uplink resources for sTTIs, reserving specific OFDM symbols for demodulation reference signals (DMRS) that can be shared between multiple sTTIs, allowing for efficient DMRS transmission and channel estimation, even in slot-aligned configurations with reduced TTI lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional reference signal patterns are used for sTTIs, then channel estimation can be performed, but resource utilization efficiency deteriorates due to redundant DMRS transmissions in each sTTI
Solution Approach 1:
The patent merges DMRS resources across multiple sTTIs by allowing a DMRS transmitted in one sTTI to be shared by subsequent sTTIs. This combining approach eliminates redundant reference signal transmissions while maintaining channel estimation capability, thereby improving resource utilization efficiency without sacrificing measurement precision.
Solution Approach 2:
The patent makes DMRS resources universal across multiple sTTIs by enabling a single DMRS to serve multiple transmission time intervals. This multi-functionality allows the same reference signal to be reused for channel estimation in different sTTIs, reducing overall resource consumption while maintaining estimation accuracy.
2Reliability
If DMRS resources are allocated for each sTTI independently, then channel estimation reliability is maintained, but resource overhead increases
Solution Approach 1:
The patent combines DMRS resources across multiple sTTIs so that a DMRS transmitted in an earlier sTTI can be used for channel estimation in subsequent sTTIs. This merging reduces the quantity of reference signals required while maintaining reliability through the shared DMRS resource pool.
Solution Approach 2:
The patent performs preliminary DMRS transmission in earlier sTTIs that can serve as reference for subsequent sTTIs. This preliminary action allows later sTTIs to reuse the pre-transmitted DMRS, reducing the need for redundant transmissions and lowering overall resource overhead while maintaining estimation reliability.
3Speed
If sTTI length is reduced for low latency communication, then transmission speed improves, but reference signal pattern complexity increases
Solution Approach 1:
The patent applies universality by making DMRS resources valid across multiple sTTIs, allowing a single reference signal pattern to serve multiple shortened transmission intervals. This approach simplifies the reference signal pattern management despite the reduced sTTI length, as the same pattern can be reused across boundaries.
Solution Approach 2:
The patent introduces dynamic DMRS resource allocation where the validity of DMRS resources extends across multiple sTTI boundaries based on configuration parameters. This dynamic approach allows the system to adapt reference signal patterns to the shortened TTI structure, managing complexity through flexible, configurable resource sharing rules.
4Measurement precision
If DMRS is transmitted in every sTTI, then channel estimation accuracy is maintained, but resource allocation efficiency deteriorates
Solution Approach 1:
The patent merges DMRS transmissions across multiple sTTIs by allowing subsequent sTTIs to reuse DMRS resources from earlier transmissions. This combining maintains channel estimation accuracy through shared reference signals while improving resource allocation efficiency by eliminating redundant transmissions.
Solution Approach 2:
The patent applies the principle of discarding and recovering by allowing DMRS resources to be discarded in later sTTIs after being transmitted in earlier sTTIs, and then recovered/reused for those later sTTIs. This approach maintains estimation accuracy while improving resource efficiency by avoiding duplicate transmissions.
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AI summary
Methods, systems, and devices for wireless communication are described that provide for identifying uplink transmissions that are to be made using shortened transmission time intervals (sTTIs), and allocating uplink resources for such transmissions. A portion of the uplink resources may be reserved for reference signal transmissions, such as demodulation reference signal (DMRS) transmissions. Resources for a number of sTTIs may be aligned within a slot that comprises a number of orthogonal frequency division multiplexing (OFDM) symbols, and one of the OFDM symbols may have resources reserved that are to be shared by two or more sTTIs within the slot for DMRS transmission. The reserved OFDM symbol may be shared by two overlapping sTTIs in which the reserved OFDM symbol is common between the two sTTIs. A DMRS sequence for each sTTI may be selected based on the allocated uplink resources for the sTTIs.