Impedance Matrix Tuning via Simultaneous Orthogonal Excitations
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Solution Overview
Problem
Current methods for automatically tuning an impedance matrix in radio transmitters used for MIMO wireless communication are not compatible with standards like LTE-Advanced, as they require sequential excitations that interfere with electromagnetic wave emission, limiting their applicability.
Innovation Solution
The method involves applying multiple excitations simultaneously as bandpass signals, allowing for the estimation of impedance matrix quantities using complex envelopes that are linearly independent or orthogonal, enabling adaptive tuning without sequential excitation and compatible with MIMO emission modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential excitations are used for impedance matrix tuning, then measurement precision is improved, but productivity deteriorates due to interference with electromagnetic wave emission in MIMO systems
Solution Approach 1:
The patent applies periodic action by using orthogonal pilot signals with specific time-frequency structures to excite multiple antennas simultaneously. The pilot signals are designed with orthogonal properties that allow the impedance matrix to be estimated from simultaneous measurements, converting the sequential measurement requirement into a parallel measurement capability while maintaining measurement precision.
Solution Approach 2:
The patent implements preliminary action by pre-designing orthogonal excitation signals (pilots) that are transmitted before actual data transmission. These preliminary excitations enable the system to estimate the impedance matrix in advance, allowing the tuning to be completed before the MIMO communication begins, thus avoiding interference with the productive electromagnetic wave emission.
2Measurement precision
If sequential excitations are applied to user ports, then impedance matrix quantities can be estimated accurately, but the method is not compatible with MIMO emission modes requiring simultaneous electromagnetic wave transmission
Solution Approach 1:
The patent uses periodic pilot signals with orthogonal properties to excite multiple user ports simultaneously. The orthogonality of these periodic signals allows the receiver to distinguish and separately estimate the impedance contributions from each transmitter antenna, achieving accurate impedance matrix estimation without requiring sequential excitation, thus making the method compatible with MIMO emission modes.
Solution Approach 2:
The patent introduces orthogonal pilot signals as intermediaries between the transmitter antennas and the impedance estimation process. These pilot signals serve as mediators that carry information about the impedance matrix while maintaining orthogonality, allowing simultaneous excitation of multiple antennas without interference, thereby enabling compatibility with MIMO standards while preserving estimation accuracy.
Data Source
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AI summary
The invention relates to a method and an apparatus for automatic tuning of an impedance5 matrix, for instance the impedance matrix seen by the power amplifiers of a radio transmitter using a plurality of antennas simultaneously. The invention also relates to a radio transmitter using this apparatus. An apparatus for automatically tuning an impedance matrix has 4 user ports (112) (122) (132) (142) and 4 target ports (111) (121) (131) (141), and comprises: 4 sensing units (1); a10 signal processing unit (2), the signal processing unit estimating real quantities depending on the impedance matrix presented by the user ports, using the sensing unit output signals obtained for 4 excitations applied to the user ports, two or more of the excitations being applied simultaneously, the signal processing unit delivering a tuning instruction; a multiple-input-port and multiple-output-port tuning unit (3) comprising adjustable impedance devices; and a tuning15 control unit (4) receiving the tuning instruction and delivering tuning control signals to the multiple-input-port and multiple-output-port tuning unit, the reactance of each of the adjustable impedance devices being mainly determined by one or more of the tuning control signals.