Null Space Beamforming for Concurrent Broadcast and Directional Signal Transmission
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Solution Overview
Problem
In Massive MIMO wireless communication networks, transmitting broadcast signals concurrently with directional device-specific signals poses challenges due to interference, as existing methods fail to effectively concentrate broadcast signal energy without disrupting directional transmissions.
Innovation Solution
The solution involves generating beamforming precoder values using orthonormal basis vectors for the null space of the channel estimate matrix, allowing broadcast signals to be transmitted in the null spaces of directional transmissions, thereby avoiding interference with device-specific signals and concentrating energy on specific antenna elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If broadcast signals are transmitted concurrently with directional device-specific signals, then broadcast signal coverage is improved, but interference with directional transmissions occurs
Solution Approach 1:
The patent segments the spatial transmission space into directional beam spaces and null space. Broadcast signals are transmitted in the null space (orthogonal complement of the channel estimate matrix), while directional signals occupy specific beam directions. This spatial segmentation allows concurrent transmission without interference.
Solution Approach 2:
The patent introduces beamforming precoder values as an intermediary mechanism. These precoders, derived from the null space basis vectors, mediate the transmission of broadcast signals by shaping the spatial distribution of signal energy to avoid directional beam regions, thus preventing interference while maintaining coverage.
2Productivity
If broadcast signal energy is concentrated on specific antenna elements, then transmission efficiency is improved, but interference with directional signals may occur
Solution Approach 1:
The patent applies local quality by concentrating broadcast signal energy on specific antenna elements (local concentration) while maintaining null-space orthogonality. The beamforming precoder values are designed to concentrate energy locally on selected antenna elements while ensuring the transmitted signal remains orthogonal to directional beam channels, thus achieving efficient transmission without interference.
3Object-affected harmful factors
If null space beamforming is used for broadcast signals, then interference with directional transmissions is avoided, but system complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating the null space basis vectors of the channel estimate matrix before broadcast signal transmission. This preliminary computation of beamforming precoder values enables the system to avoid interference without real-time complex calculations during actual transmission, reducing operational complexity while maintaining interference avoidance.
Data Source
AI summary
A broadcast signal transmission occurs concurrently with device-specific, directional transmissions but without substantially interfering with the directional transmissions, based on transmitting the broadcast signal in the null spaces of the directional transmissions. Specifically, transmission of the broadcast signal relies on beamforming precoder values formed from one or more orthonormal basis vectors for the null space of a channel estimate matrix representing the channels between a multi-element antenna array and the wireless devices targeted by the device-specific transmissions. The approach concentrates most of the broadcast signal energy for each subcarrier on a single antenna element for good broadcast-signal coverage while still yielding a beamforming solution that substantially avoids broadcast-signal interference at the devices targeted for directional transmission.