MIMO Transmit Antenna Array Phase Adjustment for Near-Field Testing
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Solution Overview
Problem
Existing MIMO signal test systems cannot accurately perform signal tests when the distance between the transmit antenna array and the receive antenna is less than a certain threshold, leading to large errors in signal metric values and failure to meet test requirements.
Innovation Solution
A method involving a transmit device that transmits orthogonal signal sequences using a transmit antenna array, where phase and attenuation adjustments are made based on calculated phase offsets and attenuation amplitudes to ensure in-phase superposition of signals at the receive antenna, even in short-distance conditions, allowing for accurate signal metric calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the distance between transmit antenna array and receive antenna is reduced below the distance threshold, then the electromagnetic anechoic chamber length can be reduced, but the signal metric measurement precision deteriorates with very large errors
Solution Approach 1:
The patent changes the phase parameters of signals transmitted by different transmit antennas based on the actual distance between the transmit antenna array and receive antenna. By calculating and adjusting phase offsets for each antenna signal, the system ensures in-phase superposition at the receive antenna even at short distances, thereby maintaining measurement precision while allowing reduced chamber length
Solution Approach 2:
The patent performs preliminary phase adjustment on the transmit signals before transmission. The phase offsets are calculated in advance based on the known geometry, and the signals are pre-adjusted to compensate for the short distance effect, ensuring that when signals arrive at the receive antenna, they are already in-phase and can be accurately measured
2Ease of manufacture
If the distance between transmit antenna array and receive antenna is reduced, then the construction cost of electromagnetic anechoic chamber is reduced, but the test accuracy deteriorates
Solution Approach 1:
The patent modifies the phase parameters of transmit signals according to the reduced distance configuration. By dynamically adjusting phase offsets based on the actual short distance between antennas, the system maintains test accuracy without requiring the large chamber dimensions that would otherwise be necessary for far-field testing conditions
3Measurement precision
If phase adjustment is applied to signals from different transmit antennas, then in-phase superposition at receive antenna is achieved, but the device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the system measures the actual channel response between transmit and receive antennas, calculates the phase offsets based on measured data, and then applies the calculated phase adjustments to subsequent transmissions. This closed-loop approach ensures accurate in-phase superposition while keeping the complexity manageable through adaptive rather than purely predetermined adjustments
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
Enables accurate signal testing without the need for a large electromagnetic anechoic chamber, reducing construction costs and expanding the test application scope by ensuring phase and attenuation adjustments for in-phase superposition of signals.
Implementation Method 1
transmitting, by a transmit device, N signal sequences by using a transmit antenna array
Implementation Method 2
adjusting an initial test signal based on the phase offset that is of each signal sequence and that is generated after the signal sequence passes through the channel, to obtain a target test signal in-phase superposed at the test device
Data Source
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Figure 3
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AI summary
A test method is provided, including: transmitting, by a transmit device, N signal sequences by using a transmit antenna array; obtaining, from a test device, a phase offset that is of each signal sequence in the N signal sequences and that is generated after the signal sequence passes through a channel; adjusting an initial test signal based on the phase offset that is of each signal sequence and that is generated after the signal sequence passes through the channel, to obtain a target test signal in-phase superposed at the test device, where the target test signal includes a plurality of signal sequences obtained by separately performing phase adjustment on the initial test signal based on the phase offset that is of each signal sequence and that is generated after the signal sequence passes through a respective channel; and transmitting the target test signal by using the transmit antenna array. In this way, the test signal after phase adjustment is in-phase superposed at a receive antenna, to obtain a valid signal, and further calculate a signal indicator of the transmit device. Because a near-field test can be implemented without a reflection surface, costs of the near-field test can be reduced. This application further discloses a transmit device, a test device, and a test system, to implement the foregoing method.