Transmitter Linearization for Out-of-Band Intermodulation Suppression
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Solution Overview
Problem
Conventional methods for digital predistortion (DPD) and feedforward (FF) linearization in wireless communication networks struggle to efficiently handle multiple digital input signals across different frequency bands, particularly in ultra-wideband systems with instantaneous bandwidths exceeding 1 GHz, leading to costly hardware requirements and inadequate suppression of intermodulation components.
Innovation Solution
A method and apparatus that selectively process intermodulation components outside the frequency bands within the instantaneous bandwidth, using a combination of cascade digital predistortion and feedforward linearization, incorporating separate DPD subparts for in-band and out-of-band signals to suppress distortion and reduce thermal requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DPD and FF linearization methods are used to handle multiple digital input signals across different frequency bands, then the system can maintain basic signal conditioning, but the hardware requirements become costly and intermodulation component suppression is inadequate
Solution Approach 1:
The patent divides the DPD processing into separate subparts: an in-band DPD subpart that processes signals within the frequency bands, and an out-of-band DPD subpart that processes intermodulation components outside the frequency bands. This segmentation allows targeted suppression of intermodulation components without requiring complex hardware across the entire instantaneous bandwidth, thereby improving suppression effectiveness while reducing hardware complexity.
Solution Approach 2:
The patent applies different processing qualities to different frequency regions: full DPD processing is applied within the frequency bands where signals are present, while a simplified out-of-band DPD subpart is applied only to intermodulation components outside the bands. This local differentiation optimizes resource allocation and reduces overall hardware requirements while maintaining effective intermodulation suppression.
2Adaptability or versatility
If the power amplifier operates with ultra-wide instantaneous bandwidth exceeding 1 GHz, then the system can support multiple frequency bands, but thermal requirements become excessive
Solution Approach 1:
The patent segments the bandwidth handling into in-band signal processing and out-of-band intermodulation component processing. By separating these functions, the power amplifier can operate efficiently across ultra-wide instantaneous bandwidths without being subjected to excessive thermal loads from processing all frequency components uniformly, thus maintaining adaptability while reducing thermal requirements.
Solution Approach 2:
The patent changes the processing parameters applied to different frequency regions: full DPD processing parameters are used within frequency bands, while reduced-parameter out-of-band DPD processing is applied to intermodulation components. This parameter differentiation allows the power amplifier to handle ultra-wide bandwidths with reduced thermal stress.
Data Source
AI summary
Supporting suppression of distortion caused by a power amplifier, “PA”, included in a transmitter system configured to perform digital predistortion, “DPD”, and feedforward, “FF”, linearization on multiple digital input signals relating to different frequency bands, respectively. The PA is used for power amplification in preparation for transmission by a wireless communication network and is operative with an instantaneous bandwidth, “IBW’”. Information is obtained identifying one or more intermodulation, “IM”, components outside the frequency bands but within the IBW, and caused by said PA. The identified IM components are selectively processed as part of said DPD to thereby suppress formation of at least some of the identified IM components, and/or as part of the FF linearization by adding reference signals to the FF linearization, which reference signals correspond to at least some of the identified IM components.