Uplink Reference Signal Placement Across Slot Boundaries
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Solution Overview
Problem
In wireless communication systems, particularly in deep-coverage scenarios like cell edges or basements, phase jumps in uplink signals cause cross-slot joint channel estimation to fail, leading to incorrect demodulation of uplink signals due to uncontrollable phase differences between time units.
Innovation Solution
A method where a terminal sends uplink signals with a first reference signal, such as DMRS or JD-RS, on specific symbols in consecutive time units to minimize phase changes, allowing accurate determination of phase jumps and enabling cross-time-unit joint channel estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal repeatedly sends uplink signals in multiple slots to improve coverage, then the coverage enhancement is improved, but phase jumps occur between different slots preventing accurate cross-slot joint channel estimation
Solution Approach 1:
The reference signal is segmented across time units, with part carried on the last M symbols of one time unit and part carried on the first N symbols of the next time unit. This segmentation allows the reference signal to span across time unit boundaries while maintaining continuity for channel estimation purposes.
Solution Approach 2:
The reference signal is prepared and positioned in advance on specific symbols (last M symbols of first time unit and first N symbols of second time unit) to ensure proper alignment and minimize phase changes before cross-time-unit joint channel estimation is performed.
2Measurement precision
If cross-slot joint channel estimation is performed to improve demodulation performance, then the data demodulation performance is improved, but phase jumps between slots make the estimation infeasible
Solution Approach 1:
The reference signal acts as an intermediary that bridges consecutive time units. By carrying the reference signal on specific symbols that span across time unit boundaries, it provides a stable reference for comparing phases between slots, enabling joint channel estimation despite the presence of phase jumps.
3Measurement precision
If the reference signal is carried on symbols at the boundary of time units, then the phase change due to channel variation is minimized, but the complexity of determining appropriate symbol positions increases
Solution Approach 1:
The parameters M and N define the number of symbols allocated for the reference signal at the boundaries of time units. By adjusting these parameters, the system can optimize the balance between phase stability and resource allocation, with M representing symbols in the first time unit and N representing symbols in the second time unit.
Data Source
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AI summary
Embodiments of this application provide a reference signal sending method, a reference signal receiving method, an apparatus, and a system. A terminal receives configuration information of a first reference signal from a network device; and sends, based on the configuration information, uplink signals to the network device in at least two time units, where the uplink signals each include uplink data and the first reference signal. In two adjacent time units, the first reference signal is carried on the last M symbols in symbols that are in a previous time unit and on which the uplink signal is located, and the first reference signal is carried on the first N symbols in symbols that are in a subsequent time unit and on which the uplink signal is located. In this way, there is a small time interval between the first reference signal in the previous time unit and the first reference signal in the subsequent time unit. This can minimize a phase change caused by a channel change, and improve a probability of correctly determining, by the network device, whether there is a phase jump between different time units, thereby improving accuracy of determining whether cross-time-unit joint channel estimation can be performed across time units.