DMRS Sharing for sTTI Channel Estimation
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Solution Overview
Problem
In wireless communication systems, especially those using short transmission time intervals (sTTIs), the overhead associated with transmitting demodulation reference signals (DMRS) is high, leading to inaccurate channel estimation and reduced throughput due to the short duration of sTTIs, making it difficult for user equipment (UE) to correctly demodulate data.
Innovation Solution
The implementation of efficient techniques for DMRS sharing across multiple sTTIs, where the base station transmits DMRS in some sTTIs and the UE uses these signals, along with signals from previous sTTIs, to perform channel estimation for demodulating data in subsequent sTTIs, thereby reducing overhead and improving estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DMRS is transmitted in every sTTI, then channel estimation accuracy is maintained, but overhead increases and throughput decreases
Solution Approach 1:
The patent combines DMRS transmissions across multiple sTTIs by allowing the UE to use DMRS from a first sTTI for channel estimation in a second sTTI. This merging approach reduces the frequency of DMRS transmissions while maintaining estimation accuracy, thereby reducing overhead and improving throughput.
Solution Approach 2:
The patent performs preliminary channel estimation using DMRS transmitted in an earlier sTTI before the actual data transmission in a subsequent sTTI. This preliminary action allows the UE to prepare channel estimates in advance, reducing the need for frequent DMRS transmissions and lowering overhead.
2Productivity
If DMRS transmission frequency is reduced, then overhead decreases, but channel estimation accuracy deteriorates
Solution Approach 1:
The patent ensures continuity of useful action by allowing the UE to continuously perform channel estimation using DMRS from previous sTTIs even when DMRS is not transmitted in every sTTI. This continuous estimation capability maintains accuracy while reducing transmission overhead.
Solution Approach 2:
The patent uses DMRS from previous sTTIs as an intermediary to enable channel estimation in current sTTIs. This intermediary approach allows the UE to bridge the gap between infrequent DMRS transmissions and the continuous need for accurate channel estimation.
3Loss of time
If sTTI duration is shortened, then latency is reduced, but DMRS overhead increases relative to data transmission
Solution Approach 1:
The patent implements periodic DMRS transmission patterns where DMRS is sent in selected sTTIs rather than every sTTI. This periodic approach reduces the relative overhead in short sTTIs while maintaining the low latency benefits of short transmission intervals.
Data Source
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AI summary
Methods, systems, and devices for wireless communications are described. In some wireless communications systems, a base station may communicate with a user equipment (UE) during short transmission time intervals (sTTIs). The base station may transmit reference signals in an sTTI for the UE to use to perform channel estimation for demodulating the data received in the sTTI. As described herein, a base station may transmit reference signals in a subset of the sTTIs used for downlink communications with the UE. The UE may receive the reference signals in the subset of the sTTIs and use these reference signals to perform channel estimation for demodulating data received in other sTTIs. In some cases, the UE may use the reference signals in one or more previous sTTIs in combination with the reference signals received in a current sTTI to perform channel estimation for demodulating data received in the current sTTI.