Master Station Optical Phase Adjustment for Millimeter Wave Beam Forming
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Solution Overview
Problem
Existing wireless communication systems using the millimeter wave band face challenges in long-range transmission due to high propagation loss, and existing beam forming techniques require complex control of optical demultiplexers at the base station, leading to inefficiencies in wavelength utilization and increased costs.
Innovation Solution
A wireless communication system that includes a master station device with a multi-wavelength light source, phase adjustment units, optical modulation units, and an optical combining unit to generate and adjust optical signals for beam forming, eliminating the need for base station control by compensating for phase rotation caused by wavelength dispersion during optical fiber transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If beam forming is performed by controlling wavelength of optical carrier using wavelength dispersion during optical fiber transmission, then long-range transmission is achieved, but device complexity increases due to requiring wavelength control mechanisms at base station
Solution Approach 1:
The patent extracts the wavelength control function from the base station and relocates it to the master station. The master station generates multiple optical signals with different wavelengths and pre-sets their phases to compensate for wavelength dispersion effects, eliminating the need for complex wavelength control mechanisms at the base station while maintaining long-range transmission capability
Solution Approach 2:
The patent applies preliminary action by having the master station pre-adjust the phases of optical signals for different wavelengths before transmission through the optical fiber. This preliminary phase adjustment compensates for the wavelength dispersion that will occur during transmission, so that when signals arrive at the base station, they are already properly phased for beam forming without requiring additional control
2Device complexity
If fixed wavelength is assigned to each antenna element without controlling wavelength, then device complexity is reduced, but wavelength utilization efficiency deteriorates
Solution Approach 1:
The patent applies local quality by assigning different wavelengths to different antenna elements and pre-configuring the phase characteristics of optical signals for each wavelength according to the specific beam forming requirements. This allows each wavelength to be optimized for its designated antenna element's function, improving wavelength utilization efficiency while maintaining simple fixed wavelength assignment at the base station
3Manufacturing precision
If wavelength interval between optical signals is increased to accommodate beam forming requirements, then beam forming performance is improved, but wavelength band usage is expanded leading to lower wavelength utilization efficiency
Solution Approach 1:
The patent applies parameter changes by optimizing the phase adjustment amounts for different wavelengths based on the optical fiber transmission characteristics and beam forming requirements. This allows precise beam forming to be achieved with smaller wavelength intervals, improving wavelength utilization efficiency while maintaining beam forming precision through careful parameter optimization rather than simply increasing wavelength separation
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
Enables efficient beam forming without requiring base station control, while maintaining wavelength utilization efficiency and reducing costs by using fixed wavelength splitting and phase adjustments to achieve directivity in RF signals.
Implementation Method 1
an accommodation station (master station) modulates intensity of an optical carrier with a radio frequency (RF) signal to be transmitted
Implementation Method 2
transmits the modulated signal through an optical fiber
Implementation Method 3
An optical demultiplexer (931) of the base station (930) separates, for each wavelength, a plurality of optical modulated signals transmitted in the optical fiber (920)
Implementation Method 4
A plurality of optical/electric (O/E) converters (932-1, . . . , 932-n) each convert the optical modulated signal of a corresponding wavelength obtained by the splitting into an electric signal
Implementation Method 5
In beam forming with an array antenna, the phase of an RF signal incident on each antenna element of the array antenna is controlled, and radio waves emitted from the antenna elements are caused to interfere with each other
Implementation Method 6
a delay difference is generated between optical signals of respective wavelengths due to wavelength dispersion during optical fiber transmission
Data Source
AI summary
A master station device is connected to a slave station device that emits a transmission signal received by light via an optical transmission path from a plurality of antenna elements. The master station device includes an optical signal output unit that outputs optical signals of a plurality of wavelengths, a phase adjustment unit that adjusts, for each wavelength, a phase of the transmission signal based on phase rotation that the optical signal is to undergo while being transmitted through the optical transmission path and a phase in one of the antenna elements corresponding to the wavelength of the optical signal, an optical modulation unit that modulates, for each wavelength, the optical signal output by the optical signal output unit with the transmission signal the phase of which is adjusted in accordance with the wavelength of the optical signal, and an optical combining unit that multiplexes the optical modulated signal of each wavelength and outputs the multiplexed signal to the optical transmission path. The slave station device includes an optical demultiplexing unit that demultiplexes the optical modulated signal transmitted through the optical transmission path and an optical/electric conversion unit that outputs the transmission signal obtained by converting the optical modulated signal of each wavelength into an electric signal to one of the plurality of the antenna elements corresponding to the wavelength.