Sampling Phase Difference Compensation in OFDM Communication Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current communication technologies, particularly those using orthogonal frequency division multiplexing (OFDM) with in-phase and quadrature-phase modulation, face IQ mismatch issues due to sampling phase differences that affect compensation results, leading to suboptimal image rejection ratios (IRR) over time.
Innovation Solution
A sampling phase difference compensation apparatus and method that generates and analyzes signals in different time intervals to determine phase differences, allowing for phase difference compensation between in-phase and quadrature-phase signals, thereby addressing frequency-dependent and sampling phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If currently known technologies are used to detect and compensate IQ mismatch, then frequency-dependent phase difference can be compensated, but sampling phase difference cannot be compensated leading to linear degradation of IRR over time
Solution Approach 1:
The patent segments the phase difference compensation into two distinct parts: frequency-dependent phase difference compensation and sampling phase difference compensation. By separating these two components, the system can address each type of phase error independently, allowing for more precise overall compensation that maintains stability over time.
Solution Approach 2:
The patent introduces an intermediary calculation method that uses known phase difference relationships to derive sampling phase difference. By using the relationship between frequency-dependent phase difference and sampling phase difference as an intermediary, the system can compensate for sampling phase difference without requiring direct measurement, thereby maintaining compensation accuracy over time.
2Manufacturing precision
If IQ mismatch compensation is performed using conventional methods, then image rejection ratio can be improved initially, but IRR degrades linearly over time due to uncompensated sampling phase difference
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors phase difference relationships and uses this information to adjust compensation parameters. By establishing a feedback loop that utilizes the relationship between frequency-dependent phase difference and sampling phase difference, the system can maintain optimal IRR performance over extended periods.
Solution Approach 2:
The patent performs preliminary calculation of sampling phase difference using the relationship with frequency-dependent phase difference before actual compensation is applied. This preliminary action allows the system to pre-compensate for sampling phase differences, preventing IRR degradation before it occurs and maintaining stable performance over time.
3Measurement precision
If only frequency-dependent phase difference is compensated, then modulation accuracy can be maintained, but sampling phase difference causes linear IRR degradation
Solution Approach 1:
The patent changes the approach from compensating only frequency-dependent parameters to also addressing sampling phase parameters. By introducing a new parameter relationship that connects frequency-dependent phase difference with sampling phase difference, the system can simultaneously maintain modulation accuracy and improve image rejection ratio without the linear degradation observed in conventional methods.
Data Source
AI summary
A sampling phase difference compensation apparatus includes a signal generator, a signal analyzer and a compensator. The signal generator generates a first signal and a second signal, and outputs the first and second signals to a first path in a first time interval and a second path in a second time interval, respectively. The signal analyzer receives a transmitted first signal from the first path and a transmitted second signal from the second path, and performs a predetermined calculation on the transmitted first and second signals to determine a phase difference relationship, which is associated with a frequency-dependent phase difference and a sampling phase difference, between the transmitted first and second signals. The transmitted first signal is associated with the first signal, and the transmitted second signal is associated with the second signal. The compensator performs a phase difference compensation according to the phase difference relationship.