Multicarrier Transmitter Subcarrier Mapping for Frequency Diversity
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Solution Overview
Problem
Multicarrier communication systems lack frequency diversity between subchannels of different spatial channels, which can reduce performance and affect users differently, especially when problematic subcarrier frequencies are present.
Innovation Solution
The solution involves varying the mapping of subcarriers and time slots across spatial channels, using techniques like circular shifting and interleaving, to ensure that each subchannel uses different subcarrier frequencies, thereby increasing frequency and spatial diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same frequency subcarriers are used in each spatial channel for subchannels, then the system structure is simple and easy to implement, but frequency diversity is reduced and performance deteriorates when problematic subcarrier frequencies are present
Solution Approach 1:
The patent applies dynamic subcarrier mapping where the mapping relationship between subchannels and frequency subcarriers varies across different spatial channels. Specifically, subchannels in different spatial channels are mapped to different frequency subcarriers, creating a dynamic and flexible mapping structure that adapts to channel conditions and provides frequency diversity while maintaining implementation feasibility through systematic mapping rules
Solution Approach 2:
The patent extends the subcarrier mapping from a single-dimensional approach (same mapping for all spatial channels) to a multi-dimensional approach by introducing spatial channel dimension. Subchannels are mapped to different frequency subcarriers across different spatial channels, effectively adding a spatial dimension to the frequency mapping and creating frequency diversity without excessive complexity
2Adaptability or versatility
If frequency diverse subcarrier mapping is implemented across spatial channels, then frequency diversity and performance are improved, but system complexity and implementation difficulty increase
Solution Approach 1:
The patent segments the frequency spectrum into different subcarrier groups that are selectively assigned to different spatial channels. By dividing the available frequency resources and assigning different segments to different spatial channels, the system achieves frequency diversity while maintaining a structured and manageable mapping complexity through systematic segmentation rules
Data Source
AI summary
A multicarrier transmitter assigns for each of a plurality of spatial channels, sets of the constellation symbols to subcarriers of each subchannel. Constellation symbol assignments to the subchannels are circularly rotated among some of the spatial channels so that subchannels use different sets of subcarriers for each spatial channel for enhanced frequency diversity.