Multicarrier Spread Spectrum Signal Generation Using Majority Voting Logic
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Solution Overview
Problem
Interplex modulation methods are inefficient for generating multicarrier spread spectrum signals with a constant envelope, especially when combining more than three codes, as they result in reduced power efficiency due to the need for numerous cross-product terms and are limited to single-carrier signals.
Innovation Solution
The method involves partitioning multiple spreading codes using majority voting logic to form modulating signals, which are then modulated and summed to create a multicarrier spread spectrum signal with a constant envelope, minimizing the use of cross-products and maximizing power efficiency by combining an odd number of codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If Interplex modulation is used to combine multiple spreading codes, then a constant envelope signal is achieved, but power efficiency deteriorates when combining more than three codes due to numerous cross-product terms
Solution Approach 1:
The patent divides the set of spreading codes into multiple subsets, with each subset containing an odd number of codes (e.g., three codes per subset). Each subset is processed independently through Interplex modulation to generate separate constant envelope signals. This segmentation allows the system to handle more than three total codes while maintaining constant envelope property and reducing cross-product complexity compared to processing all codes together.
2Loss of energy
If Interplex modulation combines an odd number of codes to achieve constant envelope, then power efficiency is optimized, but the method is limited to single-carrier signals
Solution Approach 1:
The patent combines multiple single-carrier constant envelope signals (each generated from a subset of spreading codes) to form a multicarrier spread spectrum signal. Each subset of codes modulates a separate carrier frequency, and the modulated signals are summed to create the final multicarrier output. This merging approach enables multicarrier operation while preserving the power efficiency benefits of constant envelope modulation for each carrier.
3Stability of the object's composition
If cross-product terms are used to cancel unwanted terms and achieve constant envelope, then signal stability is improved, but the number of required terms increases with more codes
Solution Approach 1:
By segmenting codes into subsets of three, the patent limits the number of cross-product terms to seven per subset (as shown in Equation 3 for N=3). This is significantly fewer than the number of cross-product terms required if all codes were combined in a single Interplex modulation, thereby reducing device complexity while maintaining constant envelope stability.
Data Source
AI summary
A method of generating a multicarrier spread spectrum signal having a constant envelope includes partitioning multiple spreading codes into at least a first portion of spreading codes and a second portion of spreading codes. First and second modulating signals, respectively, are formed from the first and second portions of spreading codes. A first carrier spread spectrum signal is modulated with the first modulating signal to form a first modulated carrier signal, and a second carrier spread spectrum signal is modulated with the second modulating signal to form a second modulated carrier signal. The first and second modulated carrier signals are summed to form the multicarrier spread spectrum signal. The method includes combining spreading codes from the multiple spreading codes using majority voting logic to form the first and second portions of spreading codes.