Position:Fiber-optic transmission radio frequency (or millimeter wave) signal raised wireless bandwidth, but the in atmosphere loss after aerial blasts off can increase, ask beehive structure transforms to small small area so, and base of station structure simplify be helpful for increasing base station number will reduce beehive to cover an area, make group net more agile thereby, the much classics be on the wane of wireless signal in atmosphere also can be reduced; Additional, benefit consumed fine serves as transmission link, have small loss, tall bandwidth and the characteristic that prevent electromagnetism interference. Be these advantages, make ROF technology in future the domain such as wireless broadband communication, satellite communications and intelligent traffic system is having wide applied perspective.
2. The current situation that ROF technology studies currently
In ROF system, because bear the weight of on smooth carrier wave, is simulative microwave signal, with traditional number photograph of fiber-optic transmission link is compared, its system is the chromatic dispersion of the function of parts of an apparatus and link oneself, nonlinear to light effect had more slashing demand. Current, still center on physical layer to the research of ROF technology, the source of millimeter wave signal that is based on microwave photon to learn for example arises, the characteristic analysis of smooth modulator, filter and improve, the chromatic dispersion of fiber-optic link is controlled, and base the systematic design such as the recycle of smooth carrier wave in the station and optimize.
Among them, with the generation of source of millimeter wave signal the technology is exemple, conventional high frequency signal produces a source to need costly Ben Zhenyuan, the heterodyne mixing technology that can use light wave will get high frequency carrier wave. In radar or fiber-optic radio (ROF) in communication system, undertake going up to signal of intermediate frequency microwave in smooth region frequency conversion, the millimeter wave signal that can get tall data is led bearing the weight of, at present more mature technology has, be based on effect of effect of the intensity modulator, XAM in be based on EAM, the XGM in be based on SOA, be based on Gao Fei linear and fiber-optic technology of the commutation on the Quan Guangpin rate of medium XPM or FWM effect.
Current, the electronic periodical that IEEE collects and Optics Letters of other and optical authoritative periodical, Optics Express published a large number of articles about ROF, but, these research stay on the level that handles technology and link system research to signal, less to the research achievement of network administrative levels. The maturity of a kind of technology is sure the drive that should rely on the market generates profit then. ROF technology should apply in effective communication system, the problem that still has a lot of reality needs to consider. For example: The interface problem in network confluence, the problem of MAC agreement, the taller gain problem of aerial and high speed shift are in slightly the problem of frequent switch in beehive and Doppler effect problem are waited a moment.
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