MIMO OFDM Signal Alignment for Interference Avoidance
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently utilizing both spatial and frequency dimensions for interference avoidance in MIMO OFDM systems, limiting spectrum efficiency and performance.
Innovation Solution
A method that determines unused combinations of space and frequency dimensions in existing links to generate new, interference-free links by assigning signals using channel precoding and null space allocation, ensuring non-interference with existing receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If spatial dimensions are exploited for interference avoidance, then new links can access channels, but the number of available spatial dimensions is limited
Solution Approach 1:
The patent transitions from exploiting only spatial dimensions to exploiting both spatial and frequency dimensions in MIMO-OFDM systems. By incorporating the frequency domain resources of OFDM, the system creates additional degrees of freedom for interference alignment, thereby resolving the limitation of available spatial dimensions while maintaining channel access capability.
2Reliability
If subspace frequency division multiplexing is used to exploit CP dimensions, then performance improves over spatial dimension schemes, but performance is limited by CP length
Solution Approach 1:
The patent merges the advantages of spatial dimension exploitation with frequency division multiplexing in a unified MIMO-OFDM framework. This combination allows the system to simultaneously utilize spatial streams and frequency resources, achieving improved transmission performance without being constrained by CP length alone, as both spatial and frequency dimensions contribute to interference avoidance.
3Productivity
If both spatial dimensions and frequency division are exploited in MIMO OFDM, then system performance improves, but interference coordination between links becomes more complex
Solution Approach 1:
The patent segments the interference coordination problem by treating spatial and frequency dimensions separately through structured precoding and resource allocation. By dividing the overall transmission into independent spatial streams and frequency subcarriers, the system manages interference coordination complexity while maintaining improved system performance through coordinated multi-dimensional resource utilization.
Data Source
AI summary
Embodiments are provided for interference avoidance based on signal alignment for multiple-input and multiple-output (MIMO) with orthogonal frequency-division multiplexing (OFDM) or OFDM access (OFDMA). The embodiments include a signal alignment scheme using both spatial and frequency dimensions. The scheme includes an existing link between an existing transmitter and an existing receiver, and a new link between a new transmitter and a new receiver. The new transmitter determines combinations of space dimensions and frequency dimensions unused in transmission on an existing link, and assigns signals for transmission on the new link at one or more of the unused combinations of space dimensions and frequency dimensions. The existing receiver is further configured to reallocate its power to release, using a greedy search algorithm, a small eigenvalue algorithm, or a best throughput algorithm, a null space of some space dimensions to the new transmitter.