Research Of Optical Metropolitan Area Network

Wide band numeral service has caused the traditional city territory networkunable to withstand carring a heavy load. WDM, as mature as the photoelectroncomponent technology, has urged city light network construction upsurge. Basedon DWDM, the band width core network does not satisfy LAN and MAN and cityterritory net is also unable to develop well.According to the present situation, thisarticle has made a more detailedanalysis and the elaboration in the view of thecurrent technical trend, and discuss one possibility to satisfy the net high bandwidth to develop the way of free space optical communication (FSO. With the rapiddevelopment of communication today, the transmission facility is more richer andconsummate. The fiber optic transmission has the capacity to repeat the sectionaway from long, and anti-electronmagetic interference, and the anti-corrosiveperformance and so on. Optical cable transmission system is becoming simple,mature, cost low. But the optical cable is very frail, and the construction for lay theoptical cable on road surface is easily destroyed. Therefore wireless transmissiontechnology has become one good substitution and the backup for the optical cabletransmission system. The microwave transmission is one very effective wirelesstransmission method, and is becoming more and more mature and widespread. Theearliest microwave transmission system transmits the net supplement and backupas the optical cable backbone, then used in the wireless access system. Recently theappearance of the microwave wide band wireless transmission technology -localmulti-spots distribution service (LMDS) has a higher band width and thebidirectional data transmission characteristic, may provide more wide bandsinteractive data and the multimedia service with a bigger flexibility. While themicrowave transmission must take the certain frequency spectrum resources, onekind of extremely limited resources. Moreover, the microwave transmission mustcarry on the frequency spectrum plan, the frequency band high, which is difficult togo past in a big way. The infrared wave band laser transmission, one new wirelesstransmission mode, is comparable to microwave region wave length.Transmittingrange farther, therefore does not have the filament laser transmission equipment tobe possible to compare with the microwave transmission equipment , which ismore nimble and convenient. Laser is coherent very good with electromagneticwave as well as the optical fiber ystem transmission, and the laser transmission hasmore merits, such as the splendid circuit (channel) selectivity, the very highreceiving sensitivity, and this will realize the frequency harmonious receive, theanti-jamming, anti-poor weather condition ability. The secrecy is also good. Themain contents of each chapter are following: First chapter shows the current city territory light network constructionupsurge from the massive science and technology literature, outlines the WDMtechnical light network characteristic and city territory light network technicalknowledge. Second chapter analysizes the concept of city territory net, and currentcityterritory net typical network plan. After the comparative analysis, it is pointed outthe city territory net development strategy should be based on 2-level exchange and3-level road selection primarily, and the core is the city territory net WDM, andthis is the foundation of the city territory network architecture and the networktechnology elaboration. Third chapter analyzed emphatically IP over DWDM and the city territorynetwork technical characteristic, the essential technology, the protection and restoreof the network, the network management and a series of questions, and the cityterritory network future development direction. In the fourth chapter, due to the d difference of light network and electricnetwork essentially, this articleiscussed the light network technical controtechnology based on MPLS,not only simple instruction of MPLS technology,but...