OFDM Symbol Mapping for Bit Error Rate Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing OFDM transmission technologies and advanced coding schemes, such as space-time block codes, often fail to interact constructively, leading to suboptimal symbol mapping on the OFDM grid, which results in reduced bit error rate, throughput, and increased delay due to mismatched radio channel conditions between resource-units.
Innovation Solution
A method where symbols related through advanced coding schemes are placed as close together as possible in the OFDM grid, with prioritization based on external radio environment factors to maintain similar radio channels, optimizing the combined usage of OFDM and coding schemes by defining preferred dimensions for mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If symbols are mapped in a conventional ordered fashion on the OFDM grid, then the implementation is simple, but the radio channel conditions between resource-units become mismatched, leading to reduced bit error rate performance
Solution Approach 1:
The patent applies dynamic mapping by adapting the symbol placement strategy to external radio environment factors. The mapping process dynamically selects between different dimensions (time or frequency) based on current channel conditions, such as Doppler spread and delay spread, to optimize the placement of code-related symbol groups while maintaining implementation feasibility.
Solution Approach 2:
The patent implements local quality by ensuring that code-related symbol groups are placed in resource-units with similar radio channel conditions. This localized optimization focuses on maintaining consistent channel characteristics for symbols that are jointly coded, thereby improving bit error rate performance without requiring complete redesign of the entire mapping system.
2Reliability
If code-related symbol groups are placed close together in the OFDM grid, then similar radio channel conditions are achieved improving bit error rate, but the mapping process becomes more complex
Solution Approach 1:
The patent reduces mapping operational complexity by dynamically selecting the primary dimension (time or frequency) based on external radio environment factors. This dynamic approach simplifies the decision-making process compared to exhaustive search methods, as it provides clear guidelines for dimension selection based on measurable channel characteristics like Doppler and delay spread.
Solution Approach 2:
The patent changes the mapping parameters adaptively by adjusting the placement strategy according to external radio environment factors. When Doppler spread is high, the system prioritizes frequency proximity; when delay spread is high, it prioritizes time proximity. This parameter adaptation simplifies operations by providing context-dependent mapping rules rather than requiring complex real-time optimization.
3Reliability
If advanced coding schemes are used to improve reliability, then bit error rate performance improves, but the interaction with OFDM transmission technology becomes suboptimal due to mismatched resource-unit conditions
Solution Approach 1:
The patent improves the interaction between advanced coding schemes and OFDM by adaptively changing mapping parameters based on external radio environment factors. The system adjusts the placement of code-related symbol groups according to measured channel characteristics, ensuring that the coding scheme operates under optimal conditions while maintaining compatibility with OFDM transmission technology.
Solution Approach 2:
The patent enhances adaptability by implementing a dynamic mapping approach that responds to changing radio conditions. This dynamic interaction allows the system to optimize the performance of advanced coding schemes under varying channel conditions, making the overall transmission system more versatile and better adapted to real-world environments.
4Reliability
If external radio environment factors are considered in symbol mapping, then bit error rate and throughput improve, but the processing requirements increase
Solution Approach 1:
The patent reduces processing requirements by changing the approach from complex optimization to parameter-based decision making. The system measures external radio environment factors (Doppler spread, delay spread) and uses these parameters to directly determine the mapping strategy, avoiding computationally intensive searches while still achieving improved bit error rate and throughput performance.
Solution Approach 2:
The patent applies local quality by focusing processing efforts on the specific parameters that matter most for the current channel conditions. Rather than processing all possible mapping configurations, the system selectively adjusts the mapping based on the dominant channel characteristics, thereby reducing overall processing requirements while maintaining performance benefits.
Data Source
AI summary
The present invention relates to a method and arrangement for symbol mapping in wireless communication systems utilizing OFDM transmission technology in combination with advanced coding schemes. In the method according to the present invention, adapted for use in a wireless communication system utilizing OFDM transmission technology, an OFDM grid is defined by at least a first dimension and a second dimensions from the dimensions time, frequency or space. The advanced coding scheme, for example Alamouti coding, outputs symbols that are related via the coding. At least some of the symbols, defining a code related symbol group should experience identical, or at least very similar, radio channels. According to one embodiment of the present invention, symbols from the same code related symbol group is placed as close together in the OFDM grid as possible.