Quadrature Mixing of Binary I/Q Signals for Shared Digital Links
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for transmitting binary baseband signals at high carrier frequencies in mobile communication systems are complex and costly due to the need for expensive digital multiplexers that cannot effectively upscale baseband signals to transmission bands.
Innovation Solution
The method involves forming sum and difference signals from binary baseband signals, which are then processed using a quadrature mixer to convert them to the carrier frequency, utilizing inexpensive analog components like IQ mixers and preprocessing stages operating in the baseband frequency domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If digital multiplexers are used to upscale baseband signals to carrier frequency, then signal transmission at high carrier frequencies is achieved, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces digital multiplexers (electronic/digital system) with an analog quadrature mixer that performs frequency upconversion. The baseband signals are modulated onto a carrier wave using analog mixing, eliminating the need for complex digital switching circuits. This substitution of digital processing with analog modulation resolves the contradiction by achieving high carrier frequency transmission without the complexity of digital multiplexers.
Solution Approach 2:
The patent changes the operating parameters from digital baseband switching to analog frequency modulation. By transforming the baseband signals into modulated carrier signals through the quadrature mixer, the system operates at the desired high carrier frequency while using simpler analog components instead of complex digital logic, thus resolving the contradiction between frequency and complexity.
2Speed
If digital multiplexers are used for signal upscaling, then carrier frequency transmission is enabled, but implementation cost increases
Solution Approach 1:
The patent substitutes expensive digital multiplexers with relatively inexpensive analog quadrature mixers and signal generators. The analog mixing approach uses standard radio frequency components that are成熟 and cost-effective, thereby enabling high carrier frequency transmission while reducing implementation costs compared to digital multiplexer-based solutions.
Solution Approach 2:
The patent employs standard, off-the-shelf analog components (quadrature mixer, signal generators, filters) that are inexpensive and widely available, rather than requiring custom-designed or specialized digital multiplexers. This use of commodity analog components reduces the overall implementation cost while achieving the desired high-frequency transmission capability.
3Ease of operation
If sigma-delta modulation is applied at carrier frequency, then direct antenna driving is possible, but device complexity and cost increase due to high-frequency sigma-delta converters
Solution Approach 1:
The patent applies sigma-delta modulation to the baseband signals before frequency upconversion, rather than at the carrier frequency. The digitally modulated baseband signals are then converted to analog and modulated onto the carrier wave. This preliminary application of sigma-delta modulation at low frequencies allows the use of simple, low-cost converters while still enabling direct antenna driving after final RF amplification, thus resolving the contradiction between ease of operation and device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient and cost-effective transmission of binary baseband signals at increased carrier frequencies using simple and affordable components, allowing for compact antenna modules and energy-efficient fiber optic transmission.
Implementation Method 1
a quadrature mixer for combining the sum signal and the difference signal and converting them upwards to a single signal with the carrier frequency
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a method and an arrangement for transmitting two binary baseband signals (I, Q) over a common digital transmission link at a carrier frequency (fc) increased compared to a cutoff frequency of the baseband signals. The method is characterized in that a sum signal (Q̃) and a difference signal (Ĩ) are generated from the binary baseband signals (I, Q), wherein the sum signal (Q̃) and the difference signal (Ĩ) are fed to inputs of a quadrature mixer (122), combined by the quadrature mixer (122), and transformed upwards to a single signal (MIQ) using a carrier frequency signal with the carrier frequency (fc), the transformed signal (MIQ) being transmitted over the digital transmission link.The arrangement is characterized by a preprocessing stage (121) to form a sum signal (Q̃) and difference signal (Ĩ) from the binary baseband signals (I, Q), and a quadrature mixer (122) to combine the sum signal (Q̃) and the difference signal (Ĩ) and to convert them upwards to a signal (MIQ) using a carrier frequency signal with the carrier frequency (fc) and to transmit the upward-converted signal (MIQ) over the digital transmission link.