Low-PAPR DMRS Sequence Mapping for Accurate Channel Estimation
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Solution Overview
Problem
Existing wireless communication systems face challenges in managing high peak-to-average power ratio (PAPR) in demodulation reference signals, which can lead to inefficiencies and interference, particularly in 5G NR technology.
Innovation Solution
The implementation of a demodulation reference signal (DMRS) with a low PAPR is achieved by using a mother sequence and applying specific shifts or clipping and filtering techniques to determine a segment of the DMRS sequence, which is then mapped to specific subcarriers in a comb structure, optimizing the DMRS for both downlink and uplink transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional DMRS sequences are used in wireless communication systems, then channel estimation can be performed, but the peak-to-average power ratio (PAPR) becomes excessively high causing transmission inefficiencies and interference
Solution Approach 1:
The DMRS sequence is segmented into multiple parts (first DMRS sequence and second DMRS sequence) that are multiplexed using different orthogonal cover codes. This segmentation allows the overall sequence to maintain low PAPR characteristics while still providing sufficient reference signals for accurate channel estimation across different time-frequency resources
Solution Approach 2:
Different orthogonal cover codes are applied to different segments of the DMRS sequence, creating local variations in the signal structure. This local quality differentiation enables the system to maintain low PAPR in each segment while collectively providing robust channel estimation capability across the entire resource allocation
2Measurement precision
If more reference signals are transmitted to improve channel estimation accuracy, then measurement precision improves, but interference increases and power efficiency decreases
Solution Approach 1:
The patent employs periodic repetition of DMRS sequences with different orthogonal cover codes applied in different periods or time slots. This periodic structure allows the receiver to average out interference over multiple periods while maintaining consistent channel estimation accuracy, and the low PAPR characteristic reduces overall interference generation
Solution Approach 2:
The DMRS transmission uses a composite structure combining multiple sequences with different orthogonal cover codes. This composite approach diversifies the signal structure to resist different types of interference while maintaining low PAPR, achieving both accurate channel estimation and reduced interference through the synergistic combination of multiple signal components
Data Source
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AI summary
A first apparatus may determine a demodulation reference signal (DMRS) sequence based on a mother sequence, map the DMRS sequence to at least a first symbol of a set of resource blocks (RBs) in a transmission., and send a DMRS including the mapped DMRS sequence in the at least one symbol of the set of RBs. A second apparatus may receive information associated with resource allocation, determine a granularity based on the information associated with resource allocation, determine resource allocation based at least in part on the granularity, and receive a signal carried on resources corresponding to the resource allocation.