Radio Base Station Beam Null Steering for Interference Mitigation
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Solution Overview
Problem
Radio communication systems face challenges in improving communication quality when a radio terminal or base station receives interference signals, as existing closed loop MIMO techniques are insufficient in addressing these interference issues.
Innovation Solution
A radio base station and terminal equipped with a transmitter, controller, and acquisition unit that direct a directional beam and null point to mitigate interference by using feedback information and control information to steer the beam away from interfering signals, enhancing communication quality even in the presence of interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the same frequency band is used by neighboring cells to efficiently utilize the frequency band, then frequency band utilization is improved, but communication quality deteriorates due to interference signals received by radio terminals and base stations
Solution Approach 1:
The patent applies local quality by creating spatial differentiation in signal transmission. The base station transmits signals with different characteristics in different spatial directions: constructive signals toward the intended radio terminal and destructive null points toward interfering terminals. This allows the same frequency to be used in neighboring cells while maintaining communication quality by making the interference localized rather than universal.
Solution Approach 2:
The patent introduces a spatial dimension to frequency reuse. Instead of treating frequency allocation as a one-dimensional problem, it adds spatial directionality through multiple antenna elements, creating a three-dimensional signal environment. This allows the same frequency to be reused in different spatial locations without causing harmful interference, effectively adding a spatial dimension to frequency management.
2Reliability
If closed loop MIMO feedback control is implemented to improve communication quality, then transmission control is improved, but communication quality cannot be sufficiently improved when interference signals are present
Solution Approach 1:
The patent introduces an intermediary mechanism for interference management. The radio terminal acts as an intermediary by measuring interference from other cells and reporting this information back to its serving base station. This intermediary feedback enables the base station to adjust its transmission characteristics to mitigate interference, extending the closed-loop control to include interference conditions rather than just channel conditions.
Solution Approach 2:
The patent enhances feedback mechanisms by including interference measurement information in the feedback loop. The radio terminal measures both the desired signal channel and interfering signals, then feeds back this composite information to the base station. This expanded feedback enables the base station to adapt its transmission to simultaneously optimize for both signal quality and interference mitigation.
Data Source
AI summary
A radio base station (BS2) comprises: a transmitter (1412) that transmits, via a plurality of transmission antennas, a radio signal to a first radio terminal having a plurality of reception antennas; a transmission directivity controller (1422) that controls directional beam, which is formed by the transmission antennas, on the basis of feedback information that is fed back from the first radio terminal; and an information acquiring unit (1421) that acquires control information to be used for directing the null points of the directional beam toward a second radio terminal that receives, as an interference signal, the foregoing radio signal during communication with another radio base station. The transmission directivity controller (1422) directs, based on the feedback information and control information, the directional beam toward the first radio terminal and the foregoing null points toward the second radio terminal.