DM-RS Pattern Selection for Sidelink LBT Clearance Timing
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Solution Overview
Problem
In wireless communication systems, particularly in sidelink transmissions, existing technologies face challenges in efficiently managing channel occupancy times and demodulation reference signals (DM-RS) patterns, leading to increased complexity and potential channel access starvation due to the need for precise timing and resource allocation in shared radio frequency bands.
Innovation Solution
The method involves performing a listen-before-talk (LBT) procedure to select either a half-slot or full-slot resource pool based on clearance timing, allowing for flexible DM-RS pattern selection and transmission of sidelink information, thereby reducing transmitter and receiver complexity and improving spectrum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple starting symbols are used for initial slot in sidelink transmissions, then channel access flexibility and spectrum efficiency are improved, but transmitter and receiver complexity increases due to multiple DM-RS patterns and scrambling sequences
Solution Approach 1:
The patent applies parameter changes by dynamically selecting different DM-RS patterns and scrambling sequences based on the LBT clearance timing. When LBT clears at specific symbol positions, the system changes the DM-RS pattern parameters (e.g., pattern type, symbol allocation) and scrambling sequence initialization values to match the available transmission resources. This allows flexible channel access while maintaining manageable complexity through standardized parameter selection rules.
Solution Approach 2:
The system implements dynamics by making DM-RS pattern and scrambling sequence selection adaptive to real-time LBT outcomes. The transmitter dynamically determines which starting symbol to use (e.g., symbol 0, symbol 2, or symbol 7) based on LBT clearance timing, and consequently dynamically selects the appropriate DM-RS pattern and scrambling sequence. This dynamic adaptation enables efficient spectrum utilization while the standardized selection criteria keep implementation complexity controlled.
2Manufacturing precision
If DM-RS patterns are selected based on LBT clearance timing, then resource allocation precision is improved, but signaling overhead and processing complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-defining multiple DM-RS patterns and their associated scrambling sequences before transmission. Each pattern is pre-configured with specific properties (e.g., DM-RS symbols at different positions, different cyclic shifts). When LBT clears, the system simply selects from these pre-prepared options based on the clearance timing, avoiding the need to generate patterns on-the-fly. This reduces processing complexity while maintaining precise resource allocation.
Solution Approach 2:
The system uses parameter changes to precisely allocate resources by selecting from pre-defined DM-RS patterns with different parameter sets. Each pattern corresponds to specific starting symbol positions and resource allocations. By changing the selected pattern parameter based on LBT timing, the system achieves precise resource allocation without complex real-time calculations, as the selection follows predetermined rules.
3Adaptability or versatility
If multiple scrambling sequences are used for different starting symbols, then channel access adaptability is improved, but power consumption increases due to increased processing
Solution Approach 1:
The patent applies parameter changes by selecting from a finite set of pre-defined scrambling sequences based on LBT clearance timing. Each scrambling sequence is characterized by specific initialization parameters (e.g., based on slot number, sequence number, and starting symbol position). The system changes the scrambling sequence parameter according to the selected DM-RS pattern, enabling adaptive channel access while limiting the number of sequences to process, thereby controlling power consumption.
Solution Approach 2:
The system uses preliminary action by pre-generating and storing multiple scrambling sequences with different initialization parameters before transmission. When LBT clears, the appropriate scrambling sequence is selected from this pre-prepared set based on the clearance timing and selected DM-RS pattern. This eliminates the need for complex real-time scrambling sequence generation, reducing processing power requirements while maintaining adaptability to different channel access scenarios.
Data Source
AI summary
A method for wireless communication at a first user equipment (UE) includes performing, in a shared radio frequency band, a listen-before-talk (LBT) procedure for a channel occupancy time (COT). The method also includes selecting a first or second starting symbol for an initial slot based on a timing associated with the LBT procedure indicating a clearance, the initial slot having a first or second total number of symbols in accordance with selecting the first starting symbol or the second starting symbol. The method further includes selecting either a first or second demodulation reference signal (DM-RS) pattern from a group of DM-RS patterns in accordance with the initial slot having the first total number of symbols or the initial slot having the second total number of symbols. The method also includes transmitting, during the COT, sidelink information to a second UE via a sequence of slots that include the initial slot.