DMRS Transmission for Frequency Offset Estimation
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Solution Overview
Problem
The existing DMRS transmission mechanism in LTE systems fails to accurately estimate frequency offset, especially in scenarios with short transmission time intervals and high-speed movements, due to insufficient DMRS symbols and lack of design for high-speed scenarios, leading to reduced accuracy in frequency offset estimation.
Innovation Solution
A demodulation reference signal transmission apparatus and method that allows a base station to send configuration indications to user equipment to transmit independent DMRS or combinations of DMRS and uplink data, enabling precise frequency offset estimation by triggering the user equipment to send additional DMRS symbols before scheduling PUSCH, especially in high-speed scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the TTI length is shortened to 0.5 ms or less to reduce data transmission delay, then the round trip time is reduced, but the number of DMRS symbols available for frequency offset estimation is reduced to only one symbol per timeslot, which reduces frequency offset estimation accuracy
Solution Approach 1:
The patent introduces a preliminary DMRS transmission before the actual data transmission in short TTI scenarios. The base station sends a configuration indication to the UE to transmit an independent DMRS or additional DMRS symbols before the PUSCH carries data. This preliminary action ensures that sufficient DMRS symbols are available for accurate frequency offset estimation even when the main data transmission interval is shortened.
2Device complexity
If the existing DMRS transmission mechanism is used in high-speed railway scenarios, then the system structure remains simple, but the large Doppler shift caused by high speed reduces the accuracy of frequency offset estimation
Solution Approach 1:
The patent applies preliminary DMRS transmission before data transmission in high-speed scenarios. The base station determines that the UE is in a high-speed scenario and sends a configuration indication to transmit independent DMRS or additional DMRS symbols beforehand. This allows the base station to perform accurate frequency offset estimation and compensation before receiving the actual data, effectively handling large Doppler shifts without complicating the overall system structure.
3Measurement precision
If independent DMRS transmission is added to ensure sufficient DMRS symbols for frequency offset estimation, then frequency offset estimation accuracy is improved, but the uplink transmission overhead increases
Solution Approach 1:
The patent implements a dynamic DMRS transmission mechanism where the base station flexibly configures whether independent DMRS or additional DMRS symbols are transmitted based on actual scenario needs. The base station sends configuration indications to the UE to adaptively adjust DMRS transmission. This dynamic approach ensures sufficient DMRS symbols for accurate frequency offset estimation when needed (in short TTI or high-speed scenarios) while avoiding unnecessary overhead in normal scenarios.
Data Source
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AI summary
The present invention provides a demodulation reference signal transmission apparatus, system, and method. The method includes: sending, by a base station, a configuration indication to user equipment UE, where the configuration indication is used to instruct the UE to send an independent DMRS and/or instruct the UE to send a combination of a DMRS and uplink data; and subsequently receiving, by the base station, the independent DMRS sent by the UE; and/or receiving the combination of the DMRS and the uplink data sent by the UE. In this way, the base station can trigger the UE to send the foregoing DMRS to complete frequency offset estimation, thereby improving accuracy of the frequency offset estimation.