Dual Carrier Modulation for OFDM Spectral Mask Compliance
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Solution Overview
Problem
Conventional OFDM systems face a tradeoff between achieving high data transfer rates and ensuring data integrity, as they must account for spectral masking requirements and interference, leading to reduced effective data transfer bandwidth and increased bit error ratios.
Innovation Solution
The system employs selective frequency domain transformation and dual carrier modulation to spread sub-carrier energy across multiple carriers, optimizing data throughput and reliability by transforming data elements into separate signal tones before transmission, using a pre-transmission conversion function like IFFT and a dual carrier modulation function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OFDM systems utilize data coding and redundancy techniques for error correction, then data integrity is improved, but effective data transfer bandwidth is reduced
Solution Approach 1:
The patent segments the available frequency spectrum into multiple sub-bands and further divides each sub-band into multiple sub-carriers. This segmentation allows the system to selectively use only the clean, interference-free sub-carriers for data transmission, thereby maintaining high data integrity without requiring excessive redundancy coding, thus preserving effective bandwidth.
Solution Approach 2:
The patent applies local quality by allowing different sub-carriers within the same OFDM symbol to have different quality characteristics. The system identifies and selects only the high-quality, interference-free sub-carriers for data transmission while excluding affected sub-carriers. This selective approach improves data integrity locally without sacrificing overall system bandwidth.
2Adaptability or versatility
If UWB systems selectively limit transmissions in certain spectral sub-ranges to adapt to spectral masks, then coexistence with other services is improved, but potential data transfer bandwidth is decreased
Solution Approach 1:
The patent segments the UWB spectrum into multiple sub-bands and further into individual sub-carriers, enabling granular control over which frequency components are transmitted. This fine-grained segmentation allows the system to precisely conform to spectral mask requirements by silencing only the specific sub-carriers that would violate regulatory constraints, while maintaining full utilization of all permissible frequency resources.
Solution Approach 2:
The patent implements dynamic spectral allocation where the set of active sub-carriers is adjusted in real-time based on channel conditions, interference levels, and spectral mask requirements. This dynamic adaptation allows the system to maximize bandwidth utilization under varying regulatory and environmental constraints, maintaining high data transfer rates while ensuring compliance.
3Reliability
If conventional OFDM systems transmit data over limited available sub-portions of a channel, then spectral mask requirements are met, but data transfer rate is reduced
Solution Approach 1:
The patent transitions from time-domain equalization to frequency-domain selective transmission by introducing multiple orthogonal sub-carriers. This dimensional change from handling interference in the time domain to the frequency domain enables the system to achieve spectral compliance while maintaining high data transfer rates through parallel transmission over many clean frequency channels.
Solution Approach 2:
By segmenting the data transmission across multiple orthogonal sub-carriers, the patent enables parallel data streams to be transmitted simultaneously over frequency-diverse channels. This segmentation allows the system to achieve both spectral compliance (by excluding problematic frequencies) and high data transfer rates (by utilizing all available clean frequencies in parallel).
Data Source
AI summary
Embodiments of the invention provide a versatile system for selectively spreading carrier data across multiple carrier paths within an Orthogonal Frequency Division Multiplexing (OFDM) system, particularly an ultra-wideband (UWB) system. The present invention provides a data input, which passes data to a randomizer. The data then passes to a convolutional code function (206), the output of which is punctured by puncturing function. An interleaver function receives the punctured code data, and cooperatively operates with a mapper element to prepare the coded data for pre-transmission conversion by an IFFT. The mapper element comprises a dual carrier modulation function, which associates and transforms two punctured code data elements into a format for transmission on two separate signal tones.