UWB Interference Mitigation via Fixed Notch and Carrier Tuning

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Solution Overview

Problem

Conventional UWB systems face challenges in mitigating interference with narrower-band systems operating in the same frequency band, particularly in creating deep and variable notches to avoid interference, which is difficult with DSSS and pulse-based techniques, limiting their effectiveness in reducing noise floor and maintaining system range.

Innovation Solution

The approach involves creating a fixed notch at a specific position relative to the UWB carrier frequency and varying the carrier frequency to align the notch with the interfering system's frequency, enabling notch depths exceeding 30 dB, applicable to all UWB technologies including OFDM, DSSS, and pulse-based systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If variable notching is implemented to avoid interference with victim systems, then interference mitigation is improved, but device complexity increases significantly for DSSS and pulse-based techniques

Engineering Contradiction:

Improveinterference with victim systemsVSAvoidnotching implementation complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Instead of making the notch filter variable (complex) to track victim frequencies, the patent inverts the approach by making the carrier frequency variable and keeping the notch filter fixed. The notch is positioned at a fixed offset from the carrier, so as the carrier frequency changes to avoid interference, the notch automatically tracks at the correct victim frequency without requiring complex variable filtering.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the parameter being varied from the notch filter characteristics (which would be complex) to the carrier frequency (which is already variable in UWB systems). By changing which parameter is adjusted - the carrier frequency rather than the notch filter properties - the system achieves interference mitigation with minimal additional complexity.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If deep notches (30 dB or more) are created to limit UWB emission at victim frequencies, then interference mitigation is improved, but implementation difficulty increases for DSSS and pulse-based techniques

Engineering Contradiction:

ImproveUWB emission at victim frequencyVSAvoidnotch depth achievement difficulty

Core Design Contradiction:

Object-affected harmful factorsVSDifficulty of detecting and measuring

Solution Approach 1:

The patent inverts the traditional approach by keeping the notch filter simple and fixed while making the carrier frequency variable. This allows deep notches to be achieved easily with simple fixed filters, eliminating the difficulty of implementing deep variable notches in DSSS and pulse-based systems.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The variable carrier frequency automatically performs the interference avoidance function that would otherwise require a complex variable notch filter. The system uses its existing frequency agility to serve the interference mitigation function, eliminating the need for additional complex filtering hardware.

Inventive Principle:

Principle #25Self-service

3Object-affected harmful factors

If OFDM technique is used to achieve variable notches with depth of 20-30 dB, then interference mitigation is improved, but implementation cost increases compared to DSSS and pulse-based techniques

Engineering Contradiction:

Improveinterference mitigation capabilityVSAvoidimplementation cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent creates a universal solution that works with all UWB modulation techniques (OFDM, DSSS, and pulse-based) by using a fixed notch filter with variable carrier frequency. This eliminates the need for OFDM-specific implementations and allows all techniques to achieve deep notches with simple, low-cost fixed filters.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the approach from modulation-specific notching (where OFDM could easily create variable notches) to a universal notching method where the carrier frequency parameter is varied. This allows DSSS and pulse-based techniques to achieve the same interference mitigation as OFDM without requiring complex variable filtering.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3168996B1Apparatus and method for interference mitigation

Publication Date: 2019.01.09 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

There is provided an apparatus in a wideband radio transceiver for mitigating interference between a wideband radio operating in a wide frequency band and a narrow band radio operating in a narrow frequency band within the wide frequency band. The effects of transmissions by the wideband radio on the narrowband radio are reduced by creating by the wideband radio, a transmitter notch of decreased transmit power centered at a frequency in the wide frequency band that is fixed in relation to the wideband carrier frequency. The wideband carrier frequency is then adjusted so that the transmitter notch is aligned with the second radio's narrow frequency band. The effects of transmissions by the narrowband radio on the wideband radio are reduced by creating by the wideband radio, a fixed receiver notch of decreased receiver gain in the wideband receiver, and aligning the narrow band signal with the fixed receiver notch.