MIMO-OFDM Transmitter Power Calibration via CDD
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Solution Overview
Problem
The existing methods for power calibration in MIMO-OFDM transmitters require sequential measurement of each antenna, leading to increased time as the number of antennas grows, making it inefficient for systems with multiple antennas.
Innovation Solution
A method that simultaneously outputs a MIMO-OFDM signal with CDD from each antenna and uses CDD characteristics at the receiving end to perform power calibration by calculating channel coefficients, channel impulse responses, and converting CDD delay values into sample units, allowing for simultaneous power calibration across all antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential measurement of each antenna is performed, then power calibration can be accurately measured, but the time required increases proportionally to the number of transmission antennas
Solution Approach 1:
The patent combines sequential antenna measurements into a simultaneous measurement process. By using CDD to create distinguishable delayed versions of the same signal across multiple antennas, the system enables parallel calibration of all antennas at once, merging what would otherwise be separate sequential operations into a single concurrent process.
Solution Approach 2:
The patent introduces a temporal dimension through CDD delays. Instead of measuring antennas in sequence along the spatial dimension, the system creates time-shifted versions of signals that map to different spatial locations. This dimensional transformation allows simultaneous measurement of multiple antennas by exploiting the time-domain separation created by CDD.
2Productivity
If the number of transmission antennas increases, then MIMO capacity improves, but the calibration process becomes more complex and time-consuming
Solution Approach 1:
The patent creates a universal calibration approach where a single signal structure (CDD-modulated OFDM signal) serves multiple functions: it simultaneously calibrates all antennas, provides channel state information, and maintains the diversity benefits needed for high data rates. This multi-functionality eliminates the need for separate calibration procedures for each antenna.
Solution Approach 2:
The patent performs preliminary signal processing by pre-calculating CDD delay values and embedding them in the OFDM signal structure before transmission. This preliminary action enables the receiving end to automatically extract calibration information without requiring complex real-time processing, thereby reducing overall system complexity despite having multiple antennas.
Data Source
AI summary
Provided is a method of calibrating a power for a multiple input and multiple output-orthogonal frequency division multiplexing transmitter having a plurality of antennas via a measurement equipment, the method including: receiving a cyclic delay diversity (CDD) signal simultaneously output from the transmitter to obtain a starting point of a frame of a corresponding signal; performing a fast Fourier transform on a sample proceeded from the starting point by an extent of a maximum CDD delay; calculating a channel coefficient; calculating a channel impulse response and a power of the channel impulse response; converting CDD delay values of each antenna into values in units of samples by using a sampling rate in the channel impulse response; mapping a peak point position of the channel impulse response to each antenna using CDD delay sample values; and simultaneously performing a power calibration of each antenna based on each peak point power.