DM-RS Sequence Initialization Across CDM Groups for Lower PAPR
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Solution Overview
Problem
High Peak-to-Average Power Ratio (PAPR) in DM-RS signals leads to clipping and spurious emissions, degrading system performance and increasing the cost and complexity of power amplifiers in wireless communication systems.
Innovation Solution
Dynamically toggle initialization values for DM-RS sequences across CDM groups based on the n SCID parameter in scheduling DCI messages to reduce PAPR, ensuring different initialization values are used for each CDM group.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DM-RS sequences are generated using a pseudo-random sequence with cell ID and scrambling code, then the signal can be uniquely identified and separated at the receiver, but the PAPR increases significantly compared to data symbols
Solution Approach 1:
The DM-RS sequence is segmented into multiple CDM groups, with each group using a separate initialization value derived from different parameters (cell ID, scrambling code ID, CDM group index). This segmentation allows the receiver to separate and process different DM-RS sequences independently, maintaining signal identification capability while distributing the PAPR issue across multiple lower-amplitude sequences rather than one high-PAPR sequence
Solution Approach 2:
Different CDM groups are assigned different initialization values and scrambling parameters, creating local variations in sequence properties. This local differentiation ensures that each CDM group can be uniquely identified and separated at the receiver while the overall PAPR is reduced because no single sequence has excessively high peak power
2Device complexity
If the same initialization value is used for all CDM groups, then the sequence generation is simpler, but the receiver cannot separate different CDM groups effectively
Solution Approach 1:
The initialization value is segmented into multiple components: a first initialization value derived from cell ID and scrambling code ID, and a second initialization value derived from the CDM group index. These components are combined to create unique initialization values for each CDM group, enabling the receiver to separate different groups while keeping the generation process systematic and manageable
Solution Approach 2:
The initialization value generation mechanism serves multiple functions simultaneously: it provides unique identification for each CDM group, enables sequence separation at the receiver, and maintains a systematic structure that can be implemented efficiently. The same generation logic is applied universally across all CDM groups, ensuring consistency while achieving differentiation
Data Source
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AI summary
A user equipment (UE) (30) is configured to enhance Demodulation Reference Signals (DM-RS) in order to reduce the Peak-to-Average Power Ratio (PAPR) to the same level as for data symbols. To accomplish this function, the UE obtains a first initialization value that is calculated based on one of a first parameter (e.g., cell ID) and a second parameter and a scrambling code ID. The UE then maps the first initialization value to either a first Code Division Multiplexing (CDM) group or a second CDM group based on the scrambling code ID. The mapping associates the first initialization value with the first or second CDM group such that the initialization value is used when generating a demodulation sequence for that CDM group.