UWB-OFDM Carrier Classification for Interference Management
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Solution Overview
Problem
Ultrawideband (UWB) systems face significant challenges in coexisting with narrowband interference (NBI), which degrades their performance and capacity due to power limitations and interference from other technologies, limiting their range and application to short-range devices.
Innovation Solution
A method is introduced that classifies UWB carriers as interfered or non-interfered based on interference temperature, allowing transmission at different power levels and employing adaptive techniques such as orthogonal frequency-division multiplexing (OFDM) and prolate spheroidal wavelet functions to manage interference, enabling opportunistic spectrum usage and reducing inter-carrier interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If UWB systems transmit at higher power levels to increase range and capacity, then communication performance improves, but interference with narrowband systems increases
Solution Approach 1:
The UWB spectrum is divided into multiple sub-carriers, allowing selective transmission on interfered and non-interfered carriers. This segmentation enables the system to transmit at higher power on non-interfered carriers while maintaining lower power on interfered carriers, resolving the contradiction between transmission power and interference generation.
Solution Approach 2:
Different power levels are applied to different frequency carriers based on local interference conditions. The system identifies interfered carriers and applies lower power locally to those specific carriers, while allowing higher power on non-interfered carriers, thus achieving local optimization of the power-interference tradeoff.
2Object-affected harmful factors
If UWB systems operate in underlay mode with strict power limits to coexist with narrowband systems, then interference is minimized, but system range and capacity are limited
Solution Approach 1:
The system segments the UWB bandwidth into multiple carriers and selectively applies underlay power limits only to interfered carriers, while allowing overlay operation at higher power on non-interfered carriers. This resolves the contradiction by enabling higher overall capacity while maintaining protection for narrowband systems on interfered carriers.
Solution Approach 2:
The system dynamically adapts its transmission strategy by classifying carriers as interfered or non-interfered based on detected narrowband signals, and adjusts power levels accordingly. This dynamic adaptation allows the system to maximize capacity on non-interfered carriers while maintaining coexistence on interfered carriers.
3Reliability
If OFDM is used to improve robustness against multipath interference, then communication reliability improves, but complexity of signal processing increases
Solution Approach 1:
OFDM divides the UWB signal into multiple orthogonal sub-carriers, transforming a single complex high-rate stream into multiple lower-rate streams. This segmentation improves robustness against multipath interference through frequency diversity while reducing processing complexity by allowing simpler modulation and coding on each individual carrier.
Data Source
AI summary
The present invention provides a system and method for transmitting an ultrawideband (UWB) signal that is composed of an orthogonal frequency-division multiplexing (OFDM) based signal that is transmitted in an underlay manner and an impulse radio based signal that is transmitted in an overlay manner. The system and method are effective in determining an interference temperature for each of multiple carriers within the UWB signal and classifying each one of the multiple carriers of the channel as being an interfered carrier or a non-interfered carrier based on the interference temperature for each one of multiple carriers. The desired signal is then transmitted on the interfered carriers at a signal power that is not greater than the power limit of the underlay UWB policy and on the non-interfered carriers at a signal power that is greater than the power limit of the underlay UWB policy.