NCT PRB Configuration for DMRS Collision Avoidance
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Solution Overview
Problem
The existing 3GPP wireless communication standards face a demodulation reference signal (DMRS) collision issue with Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS) when using the legacy PSS/SSS mapping for New Carrier Type (NCT), which affects the demodulation of Physical Downlink Shared Channel (PDSCH) in the center six Physical Resource Blocks (PRBs).
Innovation Solution
The proposed solution configures Physical Resource Blocks (PRBs) to avoid collisions by using a new DMRS pattern in the central six PRBs, selecting UE-RS placement on non-CRS OFDM symbols, and applying a 'mirror' configuration of legacy DMRS patterns to maximize commonality between FDD and TDD systems, thereby preventing collisions with legacy PSS/SSS signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the baseline PSS/SSS mapping approach is used for NCT, then the specification impact and UE implementation are simplest, but a collision occurs between PSS/SSS signals and DMRS signals
Solution Approach 1:
The patent applies local quality by configuring different DMRS patterns for different PRB groups. Specifically, the first DMRS pattern is used for PRBs in the first frequency domain range, while the second DMRS pattern is used for PRBs in the second frequency domain range. This local differentiation allows the system to avoid PSS/SSS signal collisions in specific regions (where collisions would occur) while maintaining the simple baseline mapping approach in other regions, thus resolving the contradiction between implementation simplicity and collision avoidance.
2Measurement precision
If UE-RS-based transmission schemes are used in the center six PRBs, then demodulation performance may be improved, but collision with legacy PSS/SSS signal mapping occurs at symbols 5 and 6
Solution Approach 1:
The patent applies parameter changes by modifying the DMRS pattern parameter based on the PRB index and frequency domain position. The network device configures different DMRS patterns (first pattern for first PRBs, second pattern for second PRBs) according to the specific frequency domain range. This parameter differentiation enables the system to achieve better demodulation performance in regions where UE-RS can be effectively placed, while avoiding signal collisions in regions where legacy PSS/SSS mapping is present, thus resolving the contradiction between demodulation performance and collision avoidance.
Data Source
AI summary
A system and method utilizes a selected PRB configuration for a new carrier type for a 3GPP-type wireless network. A downlink signal is received that comprises a demodulation reference signal pattern in at least one predetermined subframe of the downlink signal. The subframe comprises a first predetermined number of the plurality of orthogonal frequency division multiplex (OFDM) symbols comprising synchronization signals for a legacy version of the downlink signal and the demodulation reference signal pattern comprising a second predetermined number of OFDM symbols that are different from the first predetermined number of the plurality of OFDM symbols. After receiving the downlink signal, the demodulation reference signal pattern in the downlink signal is demodulated.