Dynamic MIMO Interference Suppression in Unlicensed Bands
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Solution Overview
Problem
In dense wireless communication networks, massive MIMO arrays face challenges in dynamically balancing interference suppression and user data beamforming due to varying interference levels from other transmitters, as static allocation of degrees of freedom does not adapt to changing interference conditions.
Innovation Solution
The solution involves dynamically allocating degrees of freedom for interference suppression based on the outcome of listen-before-talk (LBT) operations, adjusting the number of spatial nulls to optimize coexistence with interfering nodes, and using a spatial filter to determine the optimal allocation for subsequent LBT and data transmission phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed number of degrees of freedom are allocated to interference suppression, then the system maintains stable operation, but it cannot adapt to varying interference levels from other transmitters
Solution Approach 1:
The patent implements dynamic allocation of degrees of freedom for interference suppression by adjusting the number of spatial nulls based on outcomes of listen-before-talk operations and measured interference levels. This transforms the static resource allocation into a dynamic system that adapts to changing interference conditions in unlicensed frequency bands.
2Object-affected harmful factors
If more degrees of freedom are allocated to interference suppression, then coexistence with interfering nodes improves, but less resources remain for user data beamforming
Solution Approach 1:
The patent applies partial action by allocating only the necessary number of degrees of freedom for interference suppression based on actual interference conditions. Instead of consistently using maximum resources for suppression, the system dynamically determines the optimal allocation to balance interference mitigation and data transmission needs.
Solution Approach 2:
The system changes the parameter of degrees of freedom allocation dynamically based on interference measurements and LBT outcomes. By adjusting this key parameter according to channel conditions, the system optimizes the trade-off between interference suppression effectiveness and available resources for user data transmission.
3Reliability
If the number of spatial nulls is increased to suppress interference, then the likelihood of acquiring unlicensed frequency bands increases, but the beamforming performance for user data deteriorates
Solution Approach 1:
The patent dynamically adjusts the number of spatial nulls based on the outcomes of listen-before-talk operations. When interference is detected during LBT, more degrees of freedom are allocated to suppression to increase acquisition likelihood. When interference is low, fewer degrees of freedom are used, preserving beamforming performance.
Data Source
AI summary
A node is configured to be connected to a massive multiple-input, multiple-output (MIMO) array to provide spatially multiplexed channels to a plurality of user equipment in an unlicensed frequency band. The node includes a processor configured to allocate a number of degrees of freedom of the massive MIMO array to interference suppression based on an outcome of a first listen-before-talk (LBT) operation performed by the node to acquire the unlicensed frequency band. The processor is also configured to generate a spatial filter based on the number of degrees of freedom allocated to interference suppression. The node also includes a transceiver configured to perform a second LBT operation using the spatial filter.