Interference Alignment in Asymmetrical Full-Duplex Networks
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Solution Overview
Problem
Full duplex communication systems face interference issues due to multiple active transmission links in the same frequency band, limiting their spectral efficiency and scalability, especially in cellular networks where uplink transmission interferes with downlink receivers.
Innovation Solution
The method involves generating a combined channel matrix, determining null spaces and vector spaces, and performing interference alignment and zero forcing using a hardware processor to manage interference and maximize signal dimensions in full-duplex communication networks with asymmetrical channel dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full duplex communication is implemented to double spectral efficiency, then spectral efficiency is improved, but interference between uplink and downlink transmissions increases
Solution Approach 1:
The patent segments the signal space into three distinct subspaces: common subspace, individual subspace, and disjoint subspace. This segmentation allows different transmission links to operate in different spatial dimensions, reducing interference while maintaining spectral efficiency. The combined channel matrix is decomposed into these subspaces, enabling independent signal processing for each type of transmission.
Solution Approach 2:
The patent transitions from conventional single-dimension signal processing to multi-dimensional signal space manipulation. By analyzing the combined channel matrix and identifying null spaces, the system creates multiple orthogonal signal dimensions (common, individual, and disjoint subspaces). This dimensional expansion allows simultaneous transmission without mutual interference, achieving the desired spectral efficiency doubling.
2Productivity
If multiple active transmission links operate in the same frequency band, then system capacity is improved, but interference patterns become more complex
Solution Approach 1:
The patent divides the complex interference management problem into three manageable segments based on signal space decomposition: common subspace management, individual subspace management, and disjoint subspace management. Each segment has specific interference characteristics and can be handled with targeted techniques, reducing overall system complexity while supporting multiple active links.
Solution Approach 2:
The patent applies different interference management strategies to different subspaces based on their local characteristics. The common subspace requires alignment techniques, while individual and disjoint subspaces have different interference profiles that can be managed separately. This localized approach simplifies the overall interference management complexity compared to a unified approach.
3Productivity
If uplink transmission is performed simultaneously with downlink reception, then spectral efficiency is improved, but interference at downlink receivers increases
Solution Approach 1:
The patent creates additional spatial dimensions beyond the traditional uplink/downlink separation. By decomposing the channel into common, individual, and disjoint subspaces, the system enables simultaneous uplink and downlink transmissions to occur in different spatial dimensions. This dimensional separation allows uplink transmissions to proceed without causing harmful interference to downlink receivers, as their signal paths are orthogonal in the expanded signal space.
Data Source
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AI summary
Systems and methods for full-duplex communication in a communications network, including generating a combined channel matrix including two or more channel matrices and determining a null space and a basis for the combined channel matrix. Common, individual, and disjoint vector spaces are determined, and common vector space is determined for each of one or more receiving nodes and each or one or more transmitting nodes, disjoint vector spaces for each of the one or more nodes are determined based on the common vector space for each of the one or more nodes, and individual vector spaces are determined based on the common and the disjoint vector spaces. Signals are mapped at each of the nodes to determine corresponding vector spaces; and interference alignment is performed in common vector spaces and zero forcing in disjoint vector spaces using a hardware processor.