MIMO Distributed Antenna System Frequency Conversion
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Solution Overview
Problem
Existing distributed antenna systems (DAS) for wireless communications, particularly in MIMO (Multiple-Input Multiple-Output) configurations, face challenges in efficiently handling multiple-input signals over a single fiber-optic cable without signal degradation or collisions.
Innovation Solution
The implementation of a distributed antenna system configured to operate in MIMO mode, where a master unit communicates multiple signals to remote units via optical links, and frequency conversion modules are used to handle MIMO signals over a single fiber-optic cable, maintaining signal integrity and diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single fiber-optic cable is used to transmit multiple MIMO signals, then device complexity is reduced, but signal degradation and collisions occur
Solution Approach 1:
The patent applies frequency conversion to change the frequency parameter of MIMO signals before transmission over the single fiber-optic cable. By converting signals to different frequency bands, the system maintains signal integrity while reducing device complexity, as the frequency-diversified signals can be transmitted simultaneously without collision on the same cable.
Solution Approach 2:
The patent introduces frequency conversion modules as intermediary devices that process MIMO signals before they enter the fiber-optic cable. These modules act as mediators that transform multiple signals into frequency-separated forms, enabling reliable transmission over a single cable without direct signal collision.
2Productivity
If traditional SISO system is used, then device complexity is low, but spectral efficiency cannot be increased
Solution Approach 1:
The patent makes the distributed antenna system universal by enabling it to handle both traditional SISO signals and advanced MIMO signals through the same infrastructure. The system can operate in either mode depending on configuration, allowing spectral efficiency improvement while maintaining compatibility with existing single-antenna devices.
Solution Approach 2:
The patent changes the operational parameter of the antenna system from single-input single-output to multiple-input multiple-output configuration. By enabling MIMO mode with multiple antennas at both transmitter and receiver, the system achieves higher spectral efficiency while managing complexity through centralized control and signal processing.
3Area of stationary object
If multiple remote units transmit signals simultaneously to a wireless device, then coverage is improved, but signal collisions and degradation occur
Solution Approach 1:
The patent applies frequency conversion to change the frequency parameter of signals from multiple remote units before they reach the wireless device. By transmitting signals at different frequencies simultaneously, the system expands coverage area while avoiding signal collisions, as each signal occupies a distinct frequency band.
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 solution enhances the spectral efficiency and capacity of wireless communication systems by allowing multiple data streams to be transmitted over spatially-independent parallel sub-channels, thereby improving signal quality and reducing interference.
Implementation Method 1
Each remote unit is coupled to a master unit with a suitable media, such as a coaxial cable or optical fiber
Implementation Method 2
a frequency conversion module to convert the MIMO signals from a first frequency to a second frequency
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A distributed antenna system (110), comprising a master unit (46) configured to receive at least one set of multiple input multiple output (MIMO) channel signals at an original MIMO frequency from at least one signal source, at least one set of the MIMO channel signals including at least a first MIMO channel signal and a second MIMO channel signal; generate a local oscillator signal; frequency convert the at least one of the first MIMO channel signal and the second MIMO channel signal from an original MIMO frequency to a different frequency different from a first legacy service frequency band using the local oscillator signal; combine the first MIMO channel signal, the second MIMO channel signal, and the local oscillator signal for transmission; an optical link (48) operably coupled with the master unit (46); a remote unit (112) communicatively coupled with the master unit (46) via the optical link (48) for transceiving the first MIMO channel signal and the second MIMO channel signal, the unit including band processing circuitry configured to process the at least one of the first MIMO channel signal and the second MIMO channel signal; conversion circuitry configured to receive the at least one converted MIMO channel signal and to frequency convert the at least one converted MIMO channel signal from the different frequency different from the first legacy service frequency band back to the original MIMO frequency for transmission over one or more antennas (44a, 44b, 132a, 132b, 216a, 216b, 216c, 216d).