Non-Coherent PUCCH Transmission Using Orthogonal Sequences
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Solution Overview
Problem
Current wireless communication systems, particularly in 5G NR, face challenges in coherent PUCCH transmission due to degraded performance at low SNR, where the energy used for DMRS does not contain data information and channel estimation quality is reduced, leading to increased performance degradation during demodulation/decoding.
Innovation Solution
A method and apparatus for non-coherent PUCCH transmission using orthogonal sequences, where the UE maps DMRS and UCI into resource elements based on control information received from the base station, enabling dynamic and semi-static RS mode switching, and the base station estimates channel parameters to compensate and decode the uplink control signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coherent PUCCH transmission is used with DMRS for channel estimation, then channel estimation can be performed, but performance degrades at low SNR because the DMRS energy does not contain data information
Solution Approach 1:
The patent combines DMRS and UCI into a single uplink control signal transmission. By merging the reference signal and data information into one signal, the system ensures that even at low SNR, the transmitted energy contains both channel estimation information and data information, preventing the performance degradation that occurs when DMRS energy is wasted without carrying data
Solution Approach 2:
The uplink control signal serves multiple functions simultaneously: it acts as both a reference signal for channel estimation and as data carrying UCI. This multi-functional approach allows the same transmission to provide both measurement precision and reliable data delivery, especially in low SNR conditions
2Measurement precision
If DMRS is transmitted separately from UCI, then channel estimation can be performed, but the energy used for DMRS does not contain data information leading to performance degradation
Solution Approach 1:
The patent merges DMRS and UCI into a unified uplink control signal. This combination ensures that the transmitted signal contains both channel estimation information and data information in the same energy transmission, eliminating the waste of DMRS energy that occurs when DMRS is transmitted separately without carrying data
3Reliability
If orthogonal sequences are used in non-coherent transmission, then decoding performance is improved, but resource element mapping complexity increases
Solution Approach 1:
The patent changes the mapping approach by introducing orthogonal sequence multiplication. Instead of direct mapping, the UCI is multiplied by orthogonal sequences (e.g., Walsh-Hadamard codes) before mapping to resource elements. This parameter change in the mapping process maintains decoding performance while providing a systematic method to handle the complexity
Data Source
AI summary
The apparatus of wireless communication is a UE and a base station. The UE received a control information indicating a reference signal (RS) mode for a non-coherent transmission of an UCI to the base station. The UE in the RS mode may map an RS according to an RS pattern and the UCI into resource elements assigned for a PUCCH to transmit the UCI and transmit an uplink control signal including the RS and the UCI to the base station over the PUCCH. The UE may determine a RS pattern and puncture the resource elements mapped with the code point of the UCI that corresponds to the RS pattern and map the RS based on the RS pattern. The UE may map the RS based on the RS pattern and map the code point by rate matching around the resource into which the RS is mapped.