DMRS Sequence Generation Across CDM Groups to Reduce PAPR
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Solution Overview
Problem
The issue of high peak-to-average power ratio (PAPR) in DMRS transmission due to mapping the same DMRS sequence across different Code Domain Multiplexing (CDM) groups, which results in sequence value repetition in the frequency domain, is not addressed by existing 3GPP specifications, and there is a need for a solution that maintains backward compatibility and low complexity.
Innovation Solution
The proposed solution involves determining specific DMRS ports and sequences for each CDM group by using distinct initialization parameters and scrambling identities, allowing for separate DMRS sequence generation for different CDM groups, thereby avoiding sequence value repetition and reducing PAPR without altering the RE mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same DMRS sequence is mapped to antenna ports across different CDM groups, then the RE mapping is simplified and backward compatibility is maintained, but the PAPR increases due to sequence value repetition in the frequency domain
Solution Approach 1:
The invention segments the DMRS sequence generation by introducing CDM group-specific initialization parameters. Each CDM group (identified by index λ) uses a distinct initialization value cinit' = (λ + NID) mod 2 for the pseudo-random sequence generator, ensuring that sequences across different CDM groups are statistically independent. This segmentation eliminates frequency domain repetition while maintaining the overall RE mapping structure.
Solution Approach 2:
The invention applies local quality by making the DMRS sequence properties specific to each CDM group through group-specific initialization parameters. While the global RE mapping remains unchanged for backward compatibility, the local sequence characteristics (initialization values, scrambling identities) are customized per CDM group to avoid PAPR issues caused by uniform sequencing across groups.
2Object-generated harmful factors
If distinct initialization parameters and scrambling identities are used for each CDM group, then PAPR is reduced by avoiding sequence value repetition, but the complexity of sequence generation and specification increases
Solution Approach 1:
The invention changes the initialization parameters of the pseudo-random sequence generator based on the CDM group index λ. Specifically, cinit' = (λ + NID) mod 2 and nSCID' = (λ + nSCID) mod 2, where NID and nSCID are higher-layer configured parameters. This parameter change approach systematically differentiates sequences across CDM groups while maintaining a regular, specifiable pattern that does not significantly increase implementation complexity.
3Object-generated harmful factors
If the RE mapping of RS ports is changed to avoid sequence repetition, then PAPR is reduced, but backward compatibility and specification stability are compromised
Solution Approach 1:
The invention extracts the sequence differentiation function from the RE mapping structure. Instead of modifying which resource elements carry DMRS signals (the RE mapping), the solution extracts and applies CDM group-specific initialization parameters to the sequence generation process. This separation allows PAPR reduction through sequence differentiation while preserving the stable, established RE mapping rules for backward compatibility.
Data Source
AI summary
Embodiments of the present disclosure relate to methods, devices and computer readable media for Reference Signal (RS) transmission. A method for communication comprises determining one or more RS ports for RS transmission, the one or more RS ports being included in one or more RS groups. The method further comprises determining a plurality of parameters for generating a RS sequence specific to a RS group in the one or more RS groups, the RS group including at least one of the one or more RS ports. The method further comprises generating the RS sequence based on the plurality of parameters. In addition, the method further comprises transmitting the generated RS sequence over the at least one of the one or more RS ports. The embodiments of the present disclosure can solve the PAPR issue caused by mapping a same RS sequence to antenna ports across RS port groups.