Base Station Transmit Chain Calibration Using TDD and FDD Gaps
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing 5G NR MIMO base stations face challenges in efficiently calibrating RF paths without impacting user data transmission, particularly due to temperature variations and asymmetrical hardware designs, leading to reduced spectrum efficiency and ineffective calibration.
Innovation Solution
Adaptive calibration methods are employed during start-up and operating phases using orthogonal sequences and multiplexers to adjust gain, phase, and timing differences across transmit chains, leveraging guard periods in TDD frames or vacated OFDM symbols in FDD frames for calibration without disrupting data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If antenna calibration is performed by reserving time-frequency resources and halting user data transmission, then calibration accuracy is improved, but spectrum efficiency deteriorates
Solution Approach 1:
The patent applies preliminary action by performing calibration during guard periods and vacated OFDM symbols before actual data transmission begins. This allows calibration to be completed in advance using previously allocated resources, eliminating the need to halt user data transmission during calibration operations.
Solution Approach 2:
The patent implements dynamic calibration scheduling by identifying and utilizing vacated OFDM symbols that become available during data transmission. The calibration process is dynamically inserted into previously allocated resources without requiring real-time resource reservation, allowing the system to adapt to varying transmission conditions while maintaining calibration accuracy.
2Reliability
If periodic calibration is performed at regular intervals, then calibration effectiveness is improved, but processing overhead increases
Solution Approach 1:
The patent implements periodic calibration by scheduling calibration operations during regular guard periods in TDD frames or at intervals using vacated OFDM symbols in FDD frames. This maintains calibration effectiveness while utilizing previously allocated resources, reducing the need for additional processing overhead.
Solution Approach 2:
The patent recovers previously allocated guard periods and vacated OFDM symbols for calibration purposes. By reusing these previously discarded time resources, the system performs periodic calibration without incurring additional processing overhead or requiring new resource allocations.
3Adaptability or versatility
If OTA calibration is performed, then calibration flexibility is improved, but calibration precision deteriorates due to receive chain inaccuracies and hardware asymmetry
Solution Approach 1:
The patent introduces an intermediary approach by using locally generated orthogonal sequences as reference signals for calibration. Instead of relying on external OTA calibration signals that require receive chain processing, the system generates calibration references internally, eliminating the precision limitations imposed by receive chain inaccuracies and hardware asymmetry.
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
Maintains high spectrum efficiency by calibrating RF paths in real-time, optimizing resource utilization, and ensuring consistent MIMO performance without affecting data transmission rates.
Implementation Method 1
estimating, by the controller, a first response and a first time delay for each of the plurality of transmit chains by cross-correlating the first summed signal with an orthogonal sequence
Data Source
AI summary
Systems and methods for antenna calibration of transmit chains in a base station are described. In particular, the method includes determining, by a controller, that user data transmission is initiated in an operating phase of the base station. A need for calibration of a plurality of transmit chains in the base station is determined. In response to the determination, the method includes detecting an arrival of at least one of a guard period of a special time slot in a Time-Division Duplex (TDD) radio frame, and an Orthogonal Frequency-Division Multiplexing (OFDM) symbol allocated by one or more higher layers in a Frequency Division Duplex (FDD) radio frame. The method includes performing fine-tuned calibration of each of the plurality of transmit chains based on the detection.