In this paper, we present the performance analysis of the uplink channel based on the Radio-over-Fiber technology for fullduplex radio access networks. The uplink channel test bench utilizes the and layout, as well as the course of the experiment are shown. The results of monitoring the power of the signal when it passes through the segment of the Radio-over-Fiber network are presented. In the final section, we calculate the signal power at the radio remote unit for any commercial broadband access network and compare it with the bench measurements. As a result, the calculated signal level was almost 20 dB lower than the measured signal at the output of the uplink channel test setup.
In this paper, an alternative fiber-optic method for forming vortex modes based on a chiral (twisted) microstructured fiber is proposed. This fiber can be considered as a ring-core fiber with ring core formed by capillaries. Besides, optical fibers design for transmitting optical vortexes over long distances. i.e. a vortex-maintaining fiber is also proposed. This fiber is a multimode fiber with an extremely large core. A comparison of the different types of vortex generation and vortex-maintaining fibers is also given. Both proposed fibers can be used in Radio over Fiber systems applying vortex beams.
KEYWORDS: Signal generators, Radio optics, Radio over Fiber, Antennas, Modulation, Telecommunications, Fiber optics, Orthogonal frequency division multiplexing, Prototyping, Channel projecting optics
This paper describes the operation of the prototype of the Radio-over-Fiber telecommunication system with the generation of OAM signals in the W-band. A method for generation both a radio and an optical OAM signal in RoF is proposed, a method for useful information transmission using OFDM technology in the considered system is described, an approach to converting optical vortexes into the radio domain is proposed, and a feedback channel simulation in RoF systems using OAM signals is carried out.
KEYWORDS: Orthogonal frequency division multiplexing, Signal attenuation, Modulation, Radio over Fiber, Signal to noise ratio, Signal processing, Non-line-of-sight propagation, Telecommunications, Atmospheric propagation, Systems modeling
In this paper we present advanced modulation and coding techniques for telecommunication systems based on Orthogonal Frequency Division Multiplexing and Radio-over-fiber technologies operating in the subteraherz frequency range 75-110 GHz (W-band). The scheme for the Radio-over-fiber communication system based on full-optical frequency upconversion, and detailed description of the W-band wireless channel are presented. As a result, the main factors affecting the quality of the transmitted radio signal are identified, against which the developed modulation formats are aimed. Improving the efficiency of the Radio-over-fiber system is achieved in two stages: by reducing the interchannel interference due to the windowing of received signal, and reducing the peak-to-average power ratio by precoding the subcarrier frequencies of the group spectrum; by increasing the signal-to-noise ratio when using constellation rotation technique. Obtained simulation results showed that application of the proposed advanced modulation and precoding techniques in Radio-over-fiber systems provides the improvement of energy efficiency and noise immunity.
KEYWORDS: Radio over Fiber, Antennas, Telecommunications, Prototyping, Radio optics, Data transmission, Field programmable gate arrays, Signal generators, Phased arrays
The paper describes the results of experimental investigation of the bench, which represents UWB RoF communication system. This bench performs the first prototype of such system and allows it to study from different sides and on different scales. The whole scheme of the bench as well as the detailed description of its elements and characteristics are presented, also the specific issues regarding the connection of the elements are observed. The specific feature of this scheme is application of the phased antenna array as the radiating element of the radio part, which revealed the uncommon questions of matching RoF signal, being transformed from optical into radio domain. The experiment methods are explained in detail. The obtained results are presented and thoroughly analyzed, which revealed that the bench characteristics satisfy the thresholds, set before. Also the experiments on data transmission proved the possibility of successful high-speed data transmission in IR-UWB frequency range on the basis of Radio-over-Fiber technology.
KEYWORDS: Radio optics, Instrument modeling, Optical amplifiers, Switches, Switching, Photography, Radio over Fiber, Systems modeling, Telecommunications, Fiber optics
This article examines the devices for optical signal splitting and chirping device modeling. Models with splitting and switching functions are taken into consideration. The described device for optical signal splitting and chirping represents interferential splitter with profiled mixer which provides allocation of correspondent spectral component from ultra wide band frequency diapason, and signal phase shift for aerial array (AA) directive diagram control. This paper proposes modeling for two types of devices for optical signal splitting and chirping: the interference-type optical signal splitting and chirping device and the long-distance-type optical signal splitting and chirping device.
KEYWORDS: Control systems, Fiber optics, Refractive index, Radio optics, Signal attenuation, Antennas, Ultraviolet radiation, Radio over Fiber, Channel projecting optics, Telecommunications
This paper describes functional principles of a device for optical signal splitting and chirping. The offered device is to fulfill functions of such optical signal distortions compensation within FOCL RoF as linear attenuation (LA) and chromatic dispersion (CD); and it should also split optical signals for its feeding to radio emitting components, compounding aerial array (AA), and control radio emitting antenna lobe. In the meantime the device for optical signal splitting and chirping can inject losses into transferred signal, though they should be within tolerant values for conventional FOCL components.
KEYWORDS: Signal generators, Prototyping, Antennas, Telecommunications, Radio over Fiber, Modulators, Microwave radiation, Signal to noise ratio, Fractal analysis, Radio optics
Wireless part of the laboratory bench, implementing IR-UWB Radio-over-Fiber system, is described in the paper. Experimental prototype of fractal antenna radiating system (FARS) is considered, various transmission modes of the laboratory bench, which allow to investigate technical specifications, are described. Research results are presented and analyzed.
KEYWORDS: Data transmission, Pulse shaping, Gaussian pulse, Radio over Fiber, Telecommunications, Transmitters, Antennas, Signal to noise ratio, Digital signal processing, Receivers
Experimental bench, which provides high-speed data transmission for IR-UWB Radio-over-Fiber systems on the basis of Gaussian pulses, is presented in the paper. Experiment setup and results are described and discussed.
KEYWORDS: Modulators, Signal generators, Radio over Fiber, Photodiodes, Continuous wave operation, Modulation, Signal detection, Eye, Terahertz radiation, Optical amplifiers
Ultra-wideband (UWB) signal generation approach for Radio-over-Fiber (RoF) systems is proposed in the paper. Impulse-radio ultra-wideband (IR-UWB) transmission technology experimental realization comply with State Committee on Radio Frequency (SCRF) regulations is offered in the paper. Three separate IR-UWB signals with carrier frequencies 4,5 GHz, 7 GHz and 9,5 GHz are generated. Such frequencies were chosen because of SCRF spectral mask "windows". The frequencies 4,5 GHz, 7 GHz and 9,5 GHz are the central frequencies of these "windows". To assess the performance of proposed system bit error rate (BER) measurements were taken.
UWB signal generation schemes and received IR-UWB signal are shown in the figures. The correlation between BER and received optical power is given in the paper. In the case of UWB signal photonic generation approach the correlation between BER and received optical power for different SMF fiber lengths is given.
The article is devoted to the research of a method providing positive chirp of a signal on a long-haul fiber optic line. The modeling of an optical pulse duration and its chirp functions on an offered segment has allowed to estimate the parameters of a segment – distance between regeneration points and capacity level of additional radiation. The method is interesting for high-speed transmission when there is no availability to use the electronic or fiber optic chromatic dispersion compensation modules.
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