Adjacent Channel Filtering Using IF Segmentation
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Solution Overview
Problem
Current RF transceivers require high Q filters for adjacent channels operation, leading to costly and complex solutions, and existing devices for interference cancellation are expensive and sensitive due to the need for phase correction using vector modulators or phase shifters, which are not feasible in standard RF transceivers.
Innovation Solution
A method and device for adjacent channels operation that downconverts the input signal to an intermediate frequency (IF), filters the IF signal, and upconverts it back to the original frequency using standard local oscillators and filters, eliminating the need for high Q filters, and incorporates a highly isolated, circularly polarized smart antenna with recessed corner patches for improved isolation and interference reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high Q filter is used in the RF transceiver for adjacent channels filtering, then the filtering precision is improved, but the device complexity and cost increase
Solution Approach 1:
The filtering function is segmented from the RF transceiver and placed at the IF stage. Instead of requiring a high Q filter in the RF domain, the patent divides the signal processing into RF downconversion, IF filtering, and upconversion segments. This allows using a lower Q filter at IF frequency, reducing the complexity and cost while maintaining adjacent channel rejection performance.
Solution Approach 2:
The IF (intermediate frequency) signal serves as an intermediary between the RF input and output signals. By downconverting to IF, filtering, and then upconverting back, the patent uses the IF stage as a mediator to perform the filtering function with a simpler, lower Q filter, avoiding the need for complex high Q filters in the RF domain.
2Object-affected harmful factors
If interference cancellation devices are used with phase correction, then the interference rejection is improved, but the device complexity and sensitivity increase due to vector modulators or phase shifters
Solution Approach 1:
The patent extracts the phase correction and interference cancellation functions from the RF transceiver and relocates them to the baseband processing stage. By taking out these sensitive components (vector modulators, phase shifters) from the RF domain and placing them at baseband, the system achieves interference rejection without requiring expensive and sensitive RF-phase controlling components.
Solution Approach 2:
The patent replaces the mechanical/RF-based phase correction system (using vector modulators or phase shifters) with a digital/baseband processing system. Instead of using sensitive RF components for phase and amplitude control, the invention uses baseband signal processing to achieve the same interference cancellation effect, substituting complex RF mechanics with simpler digital signal processing.
3Ease of manufacture
If standard RF transceivers are used without high Q filters, then the ease of manufacture and cost are improved, but the adjacent channels filtering capability deteriorates
Solution Approach 1:
The patent changes the operating frequency parameter for the filtering stage. Instead of filtering at the high RF frequency where high Q filters are needed, the system downconverts to a lower IF frequency where standard, lower Q filters can be used. This parameter change (from RF frequency to IF frequency) allows using inexpensive standard filters while maintaining filtering effectiveness.
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
This approach simplifies and cost-effectively achieves sharp filtering of adjacent channels, reducing interference and enabling efficient operation of multiple access points on adjacent channels without performance degradation, while using standard RF transceivers and off-the-shelf components.
Implementation Method 1
downconverting the input signal to an IF signal
Implementation Method 2
filtering the IF signal
Implementation Method 3
upconverting the filtered IF signal to the original frequency
Data Source
AI summary
A method and device for adjacent channels operation based on downconverting the input signal to an IF signal, filtering the IF signal, and upconverting the filtered IF signal to the original frequency. The present invention is primarily directed to applications involving the use of standard RF transceiver which does not incorporate a high Q filter. Moreover, the present invention may be used with a circular polarized cross recessed corners stacked array antenna in order to further improve its adjacent channels operation performance.