OFDM Transmitter Scramble Selector for PAPR Reduction
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Solution Overview
Problem
Existing OFDM transmitters face challenges in enhancing multi-cell diversity gain and reducing peak-to-average power ratios (PAPRs) simultaneously, which can lead to destructive interference and nonlinear distortion, especially in single frequency network (SFN) environments with poor channel frequency responses and long fading coherent times.
Innovation Solution
The proposed transmission architecture includes a forestage module, pilot insertion, scramble selector, and backstage module, where a pilot signal is inserted into the frequency domain data symbol, and scramble patterns are used to generate symbols with minimal PAPR, eliminating the need for additional side information and maintaining original receiver functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diversity transmission technique is used to enhance multi-cell diversity gain, then receiving performance is improved, but peak-to-average power ratio increases causing nonlinear distortion
Solution Approach 1:
The patent applies preliminary action by inserting pilot signals into frequency domain data symbols before scrambling and OFDM modulation. This preliminary insertion of known reference signals enables the receiver to estimate channel frequency response in advance, allowing for effective diversity combining without requiring excessive power amplification that would cause nonlinear distortion.
Solution Approach 2:
The patent changes parameters by applying different scramble patterns to different cells in the single frequency network. This parameter variation in the scrambling domain creates diversity in channel frequency response while maintaining controlled power characteristics, resolving the contradiction between diversity gain and PAPR reduction.
2Object-generated harmful factors
If scramble patterns are applied to reduce PAPR, then nonlinear distortion is reduced, but channel frequency response diversity may be insufficient
Solution Approach 1:
The patent applies local quality by using cell-specific scramble patterns that are locally optimized for each transmitter's channel conditions. Each cell uses a tailored scramble pattern that reduces its specific PAPR issues while maintaining the necessary channel frequency response diversity through the pilot signal insertion and correlation-based combining at the receiver.
3Measurement precision
If pilot signal is inserted before scrambling, then channel frequency response estimation is improved, but system complexity increases
Solution Approach 1:
The patent merges the pilot signal insertion with the existing data symbol structure in the frequency domain, combining reference signaling with data transmission in a unified framework. This merging approach improves channel estimation precision while avoiding the need for separate pilot transmission channels, thereby limiting the increase in system complexity.
4Productivity
If SFN architecture is used to save frequency resources, then frequency efficiency is improved, but destructive interference occurs at coverage boundaries
Solution Approach 1:
The patent changes parameters by introducing cell-specific scramble patterns in the SFN architecture. This parameter variation ensures that signals from different transmitters have different phase characteristics at coverage boundaries, preventing consistent destructive interference while maintaining the frequency efficiency benefits of SFN operation.
Data Source
AI summary
This invention provides a transmission architecture of transmitter which includes a forestage module, a pilot insertion, a scramble selector, and a backstage module. A frequency domain data symbol is transmitted by the forestage module. A pilot signal is inserted in the frequency domain data symbol by the pilot insertion, and a frequency domain pilot symbol is produced. The frequency domain pilot symbol performed a scramble operation and a select operation with certain scramble patterns by the scramble selector, and a requirement symbol is produced. The requirement symbol is converted into the transmitted signal by the backstage module. Because the use of the scramble operation and the select operation from the scramble selector, the transmission architecture of transmitter provided by this invention can both reduce the PAPR and increase the multi-cell diversity gain in an OFDM single frequency network system.