Moving-Object Control Apparatus Using Reference-Signal Beam Nulling
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Solution Overview
Problem
In satellite IoT platforms, interference signals from numerous ground IoT terminals make it difficult to estimate the propagation channel of desired signals, leading to reduced reception sensitivity due to interference, especially when the interference signal power exceeds that of the desired signal.
Innovation Solution
A control device installed on a moving object, such as a low orbit satellite, uses a reception unit to acquire reference signals from nearby communication devices, an extraction unit to separate these signals, and a beam control unit to direct nulls of reception beams towards interference sources based on estimated propagation channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ZF or MMSE method is used to direct reception beam, then reception sensitivity is improved, but interference suppression becomes insufficient when interference signal power exceeds desired signal power
Solution Approach 1:
The patent applies preliminary action by constantly directing the null of the reception beam in the arrival direction of the interference signal before the interference fully degrades the desired signal reception. This proactive beam nulling approach prevents interference from overwhelming the desired signal, allowing subsequent demodulation to succeed. The system continuously tracks and suppresses interference sources ahead of time rather than reacting after interference damage occurs.
2Object-affected harmful factors
If null is directed to interference signal source, then interference suppression is improved, but device complexity increases due to constant beam direction adjustment
Solution Approach 1:
The patent introduces an intermediary approach by using the arrival direction information of interference signals as a mediator to control the beam null direction. Instead of directly processing complex interference patterns from numerous ground IoT terminals, the system uses the simpler parameter of arrival direction (angle of arrival) as an intermediary to guide the beamforming weights. This reduces the complexity of constant beam direction adjustment while maintaining effective interference suppression.
3Measurement precision
If signal sequence and arrival timing of interference signal are unknown, then interference source identification becomes difficult, but reception sensitivity cannot be improved without accurate interference suppression
Solution Approach 1:
The patent applies parameter changes by shifting from trying to detect unknown signal sequences and arrival timings to using the arrival direction (spatial parameter) as the primary detection parameter. Since the arrival direction of interference signals can be estimated through spatial processing even when signal characteristics are unknown, the system changes the detection parameter from temporal/signal-specific features to spatial/angular features. This enables interference source identification and null direction control without requiring knowledge of the interference signal sequence or timing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the reception sensitivity of wireless signals from IoT terminals by effectively suppressing interference, allowing for clearer signal demodulation and data collection.
Implementation Method 1
a beam control unit that directs a null of a reception beam in an arrival direction of the reference signal based on the first propagation channel
Data Source
AI summary
There is provided a control device of a wireless communication system including the control device that is installed on a moving object and moves, a first communication device that transmits a desired signal to the control device by a first wireless method, a second communication device that transmits an interference signal interfering with the desired signal by a second wireless method, and one or more third communication devices, the control device including: a reception unit that acquires a wireless signal including a reference signal transmitted from the third communication device in the vicinity of the second communication device by a third wireless method and a desired signal transmitted from the first communication device by the first wireless method; an extraction unit that extracts the reference signal from the wireless signal based on the third wireless method; an estimation unit that estimates a propagation channel between the third communication device and the control device based on the reference signal; and a beam control unit that directs a null of a reception beam in an arrival direction of the reference signal based on the propagation channel.