IIR Up-Down Conversion with Phase Compensation for Low Delay
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Solution Overview
Problem
Conventional FIR filters in relay systems experience significant processing delays during up-down conversion procedures, leading to intersymbol interference and degraded system performance, as they cannot reduce delay time while maintaining filter magnitude response characteristics.
Innovation Solution
Implementing IIR filters for digital up-down conversion, which have stable magnitude response characteristics and reduced processing delay times compared to FIR filters, by using a magnitude response IIR filter with coefficients calculated via the Levinson polynomial and a phase compensation IIR filter to linearize non-linear phase responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an FIR filter is used for digital up-down conversion, then the magnitude response characteristic is maintained, but the processing delay time increases significantly
Solution Approach 1:
The patent changes the fundamental parameter of the filter type from FIR (Finite Impulse Response) to IIR (Infinite Impulse Response). This parameter change allows the system to achieve the same magnitude response characteristic with significantly reduced processing delay time, as IIR filters have inherent feedback mechanisms that reduce the number of taps required while maintaining frequency response properties.
Solution Approach 2:
The patent introduces a phase compensation filter as an intermediary component that works in conjunction with the IIR filter. This intermediary element compensates for the non-linear phase response of the IIR filter, effectively mediating between the time efficiency of IIR and the performance requirements of the communication system.
2Productivity
If the processing delay time is reduced below a given limit, then the system performance improves, but the magnitude response characteristic deteriorates
Solution Approach 1:
The patent employs parameter changes by transitioning to IIR filter architecture, which fundamentally alters the delay-time versus magnitude-response trade-off. IIR filters achieve their filtering function with fewer coefficients and lower delay compared to FIR filters, thereby improving system performance while maintaining the required magnitude response characteristics.
Solution Approach 2:
The IIR filter structure inherently uses feedback mechanisms where past output values are fed back into the filtering process. This feedback principle allows the filter to achieve stable magnitude response characteristics with reduced processing delay, as the feedback loop enables the system to maintain frequency selectivity without requiring long filter lengths.
Data Source
AI summary
A method and an apparatus for digital up-down conversion using an Infinite Impulse Response (IIR) filter are provided. The method for digital up-down conversion for frequency conversion in a mobile communication system using plural frequency converts, includes IIR-filtering, by a magnitude response IIR filter having the same magnitude response as in Finite Impulse Response (FIR) filtering, an input signal and a stable filter coefficient calculated according to a Levinson polynomial; and receiving, by the magnitude response IIR filter, the IIR filtered signal, and performing IIR filtering by a phase compensation IIR filter having a filter coefficient compensating for a non-linear phase to a linear phase.