Analog RoF TDD Timing Synchronization with WDM Delay Paths
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Solution Overview
Problem
In radio communication using analog RoF, synchronization of transmission and reception timings between extension stations is challenging due to varying signal propagation times, leading to potential collisions and reduced communication efficiency.
Innovation Solution
Implementing uplink and downlink delay adjustment units using wavelength division multiplexing (WDM) to adjust propagation delays of analog signals, ensuring synchronized timing for TDD operations by separating uplink and downlink paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If analog RoF is used for communication between aggregation station and extension station, then transmission capacity is suppressed and device complexity is reduced, but timing synchronization becomes difficult and communication efficiency deteriorates
Solution Approach 1:
The patent segments the signal transmission path into separate uplink and downlink paths using wavelength division multiplexing. The uplink path carries signals from extension stations to the aggregation station, while the downlink path carries signals from the aggregation station to extension stations. This segmentation allows independent delay adjustment for each direction, resolving the timing synchronization issue while maintaining the simplicity of analog RoF.
Solution Approach 2:
The patent introduces delay adjustment units as intermediary components in the uplink and downlink paths. These units act as mediators that compensate for propagation time differences without requiring complex digital buffering. The delay adjustment units are positioned to adjust the timing of signals before they reach the aggregation station or after they leave, enabling synchronization while maintaining analog signal simplicity.
2Measurement precision
If signal propagation time difference is compensated by forwarding signals, then downlink timing is synchronized, but uplink reception timing is delayed and communication efficiency is reduced
Solution Approach 1:
By segmenting the transmission paths into separate uplink and downlink channels using wavelength division multiplexing, the patent enables independent delay compensation for each direction. The downlink path can forward signals to compensate for propagation delay, while the uplink path can receive signals at their natural arrival time without additional delay, thus resolving the time loss issue while maintaining synchronization accuracy.
Solution Approach 2:
Instead of uniformly forwarding all signals to achieve synchronization, the patent applies delay adjustment selectively and differently for uplink and downlink paths. The downlink signals are forwarded to compensate for propagation delay, while uplink signals are received at their natural timing. This inverted approach to delay compensation resolves the contradiction between synchronization accuracy and communication time loss.
3Measurement precision
If digital signals are used with buffering function, then timing synchronization is achieved, but device complexity increases and analog signal simplicity is lost
Solution Approach 1:
The patent replaces the digital buffering mechanism with an optical-based delay adjustment approach. Instead of converting analog signals to digital, buffering them, and converting back (which would increase complexity), the patent uses optical fibers with different lengths or optical delay elements to achieve the same timing adjustment function. This substitution maintains the simplicity of analog signal processing while achieving precise timing synchronization.
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 enhances communication quality by preventing timing collisions and maintaining efficient communication efficiency in radio communication systems.
Implementation Method 1
a downlink delay adjustment unit located on a second path, which is spatially separated from the first path, and through which a downlink signal propagates
Implementation Method 2
analog optical modulation signals are used for communication between radio communication devices corresponding to the CU and the DU
Data Source
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AI summary
According to one aspect of the present invention, there is provided a radio communication device that performs communication with a terminal-side communication device having an antenna using an analog signal for transmitting information by a waveform of an amplitude or a phase of light to receive a signal received by the antenna and transmit a signal radiated by the antenna, the terminal-side communication device and the radio communication device being included in a radio communication system that performs radio communication with a communication target terminal via the antenna using time division duplex (TDD), the radio communication device including: an uplink delay adjustment unit configured to adjust a delay caused by propagation of an uplink signal that is a signal flowing from the terminal to the radio communication device via the antenna; and a downlink delay adjustment unit configured to adjust a delay caused by propagation of a downlink signal that is a signal flowing from the radio communication device to the terminal via the antenna.