Reference Signal Allocation in OFDMA Systems
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Solution Overview
Problem
Existing OFDM wireless communication systems face challenges in optimizing reference signal allocation, particularly when resource blocks are contiguous, as conventional designs lead to inefficient channel estimation and increased complexity due to irregular RS-RE distribution and reduced performance compared to uniform spacing.
Innovation Solution
A method for determining reference signal positions in the frequency-time domain of OFDMA systems, where reference signal patterns are optimized for both non-contiguous and contiguous resource block allocations by selecting and puncturing sub-carriers based on a mother pattern, and using predefined patterns or equations to ensure uniform spacing and efficient resource allocation across multiple resource blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference signals are placed at the edge of resource blocks to improve channel estimation performance, then channel estimation performance is improved, but the reference signal distribution becomes irregular and complexity increases when multiple resource blocks are contiguous
Solution Approach 1:
The patent segments the reference signal allocation into two distinct patterns: a first reference signal pattern for the first resource block and a second reference signal pattern for subsequent resource blocks. This segmentation allows each pattern to be optimized independently - the first pattern places RS-REs at the edge for single-RB cases, while the second pattern uses uniform spacing for multi-RB contiguous allocations, thereby reducing overall complexity while maintaining estimation performance.
Solution Approach 2:
The patent applies different reference signal patterns to different resource blocks based on their specific characteristics. The first resource block receives a different pattern than subsequent resource blocks, allowing each location to have the optimal local configuration for its specific role in the allocation, whether edge-case or contiguous-case.
2Device complexity
If uniform reference signal spacing is used across multiple resource blocks, then reference signal distribution becomes regular and simpler, but channel estimation performance deteriorates due to reduced density at edges
Solution Approach 1:
The patent divides the reference signal allocation into different patterns based on resource block position. The first pattern (for first RB) uses edge placement for high density, while the second pattern (for subsequent RBs) uses uniform spacing. This segmentation allows the system to achieve both high estimation performance where needed and simplicity where appropriate.
3Measurement precision
If reference signal patterns are optimized for single resource block allocation, then channel estimation is improved for that case, but performance deteriorates when multiple resource blocks are contiguous
Solution Approach 1:
The patent segments the reference signal patterns into at least two distinct patterns that can be selectively applied based on the allocation scenario. The first pattern optimizes for single-RB edge cases, while the second pattern optimizes for multi-RB contiguous cases, enabling the system to adapt to different allocation scenarios without compromising performance.
Solution Approach 2:
The patent introduces dynamic pattern selection where the reference signal pattern is not fixed but adapts based on the resource block allocation characteristics. The system dynamically chooses between the first and second patterns depending on whether the allocation is single-RB or multi-RB contiguous, making the system versatile and adaptive to different deployment scenarios.
Data Source
AI summary
A method is provided for determining reference signal positions in a frequency-time domain in an Orthogonal Frequency Division Multiple Access (OFDMA) system. A plurality of sub-carriers are selected in one resource block according to a predetermined mother pattern for reference signal allocation. When a single resource block is assigned for transmission to a user, the reference signal positions are determined corresponding to the plurality of selected sub-carriers in the single resource block. When multiple resource blocks are assigned for transmission to a user, the reference signal positions are determined in the multiple resource blocks by reducing a number of the plurality of selected sub-carriers in the mother pattern for at least one of the multiple resource blocks.