PCFICH Symbol Mapping for Odd Resource Blocks
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Solution Overview
Problem
In 3GPP LTE systems, the conventional mapping method for the Physical Control Format Indicator Channel (PCFICH) results in resource element wastage and mapping difficulties, especially when the number of resource blocks in the downlink is odd, leading to inefficient resource utilization and interference issues due to varying cell IDs.
Innovation Solution
A modified mapping method that adjusts the starting position of symbol mapping for the PCFICH based on whether the number of resource blocks is odd or even, using specific mathematical expressions to determine the start position, ensuring efficient allocation across four frequency regions and reducing interference by accounting for cell IDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the conventional mapping method is used for PCFICH, then the mapping rule is simple, but resource element wastage occurs when the number of resource blocks is odd
Solution Approach 1:
The mapping method dynamically adapts based on whether the number of resource blocks is even or odd. When odd, the system adjusts the starting position calculation by using (N_RB_DL - 1) instead of N_RB_DL, and modifies the frequency region assignment to prevent resource element wastage while maintaining mapping simplicity through conditional logic.
2Ease of operation
If the conventional mapping method is used for PCFICH, then the implementation is straightforward, but mapping cannot be performed in certain regions when N_RB_DL is odd
Solution Approach 1:
The invention applies different mapping strategies to different frequency regions based on the number of resource blocks. When N_RB_DL is odd, specific adjustments are made to the starting position calculations for certain frequency regions to ensure complete mapping coverage without leaving unmappable regions, while maintaining the original straightforward approach in other areas.
3Reliability
If fixed starting position k0 is used based on cell ID, then cell-specific mapping is achieved, but interference issues arise due to varying cell IDs
Solution Approach 1:
The system performs preliminary adjustments to the starting position calculation by incorporating (N_RB_DL - 1) when the number of resource blocks is odd, before the actual mapping process begins. This preliminary action ensures that the PCFICH mapping is properly aligned with the resource block structure, preventing interference issues that would arise from mismatched positioning across different cells.
Data Source
AI summary
A method of mapping symbols of a physical control format indicator channel (PCFICH) is described. A start position of a resource element to map the symbols for the PCFICH is determined by flooring a value, obtained by multiplying the number of resource blocks by a variable proportional to a symbol index for the PCFICH and then dividing the multiplied result by 2, wherein the resource blocks are transmitted in downlink. The symbols are mapped in the start position. Therefore, a problem of wasting resource elements or not being able to implement mapping can be solved by applying a simple mapping rule while mapping symbols of the PCFICH.