Multi-Band IMD Correction via Selective Frequency Translation
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Solution Overview
Problem
Conventional Digital Predistortion (DPD) architectures for concurrent multi-band transmitters face challenges in efficiently correcting Intermodulation Distortion (IMD) products, particularly those that are not simple odd-order products, leading to increased computational complexity and inefficiency.
Innovation Solution
A method and system for generating an IMD correction signal as a function of multiple frequency band inputs, frequency translating it to the desired IMD product location, and using it to compensate for specific IMD products, utilizing a combination of basis functions and complex coefficients to selectively target and cancel even or odd-order IMD products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DPD architectures correct all IMD products in concurrent multi-band transmitters, then distortion correction completeness is improved, but computational complexity increases significantly
Solution Approach 1:
The patent segments the IMD correction task by identifying and targeting only specific IMD products that fall within the transmission bands, rather than correcting all possible IMD products. This is achieved by calculating IMD product frequencies using the formula f_IMD = |c1*f1 + c2*f2| and selecting only those that lie within the operational bands, thereby dividing the complex correction problem into manageable segments.
Solution Approach 2:
The patent applies local quality by implementing band-specific correction strategies where different correction approaches are used for different frequency bands. The system identifies which bands contain IMD products and applies correction only to those specific bands, rather than uniformly correcting all bands, thus optimizing computational resources where they are most needed.
2Ease of operation
If conventional DPD architectures translate all signals to baseband for processing, then processing uniformity is improved, but bandwidth requirements and sample rate increase
Solution Approach 1:
The patent transitions from a single baseband processing dimension to a multi-dimensional approach by maintaining signals in their native frequency domains and introducing a frequency selection dimension. Instead of translating all signals to baseband (one dimension), the system operates in multiple frequency dimensions simultaneously, selecting and processing only the relevant IMD products at their appropriate frequency locations, thereby reducing the overall processing burden.
3Reliability
If conventional DPD architectures generate all higher order terms for IMD correction, then correction coverage is improved, but computational complexity and generation of unnecessary correction terms increases
Solution Approach 1:
The patent extracts only the necessary IMD correction terms from the complete set of possible higher order terms. By calculating which IMD products fall within the transmission bands using the frequency relationship f_IMD = |c1*f1 + c2*f2|, the system extracts and processes only those specific terms that require correction, discarding or ignoring terms that would generate corrections outside the operational bands.
Solution Approach 2:
The patent applies partial action by implementing correction for only the necessary subset of IMD products rather than all possible higher order terms. The system performs exactly the amount of correction needed - no more, no less - by identifying which IMD products affect the transmission bands and applying correction only to those, avoiding the excessive computation of unnecessary correction terms.
Data Source
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AI summary
Systems and methods are disclosed herein for selectively compensating for a specific Intermodulation Distortion (IMD) product(s) of an arbitrary order in a transmitter system. In some embodiments, a method of compensating for one or more specific IMD products in a concurrent multi-band transmitter system comprises generating (100) an IMD correction signal for a specific IMD product as a function of two or more frequency band input signals for two or more frequency bands of a concurrent multi-band signal, the IMD product being an arbitrary order IMD product. The method further comprises frequency translating (102) the IMD correction signal to a desired frequency that corresponds to a Radio Frequency (RF) location of the specific IMD product and, after frequency translating the IMD correction signal to the desired frequency, utilizing (104) the IMD correction signal to compensate for the specific IMD product.