【正文】 樓居住者的正常工作，因此這類(lèi)活動(dòng)通常是，有主要的結(jié)構(gòu)性翻新工程時(shí)才進(jìn)行的。這一切都意味著 費(fèi)用。為改善這種大眾媒體的帶寬能力已付出了艱苦的努力。這只是一個(gè)你愿意為編碼器和解碼器支付多少的問(wèn)題！ 銅線纜的 限制 在非常高的數(shù)據(jù)速率對(duì) UTP 銅纜布線的使用有內(nèi)在的局限性。數(shù)據(jù)線纜分享鄰近的包含總線布線的電纜這是極為重要的。這些薄弱接收信號(hào)可以從發(fā)射器耦合器淹沒(méi)不需要的信號(hào)。除了這些“流動(dòng)的”方面的銅解決方案 ,還應(yīng)該牢記影響他們的選擇的其他因素。大約有其互操作性和對(duì)現(xiàn)有設(shè)施的向后兼容的進(jìn)一步擔(dān)憂。所有的改善將是在犧牲更加昂貴的收發(fā)器的基礎(chǔ)上。普通多模光纖的折射率分布并不遵循跨越核心直徑的理想拋物的變化。他們又提高了在多模光纖上可傳播的吉比特以太網(wǎng)的距離到大約1km。 未來(lái) 顯然 ,對(duì)未來(lái)的所有需求預(yù)測(cè)是困難重重的 ,我們必須依賴(lài)于過(guò)去的經(jīng)驗(yàn)。鑒于此 ,正確的選擇水平布線是至關(guān)重要的。 對(duì)于 10 Gbs 的工作，延長(zhǎng)工作 50/125μ m 的光纖電纜是必需的。一種實(shí)現(xiàn)這一沒(méi)有鋪設(shè)任何實(shí)際的光纖的方法就是是使用“ 氣吹光纖 ”導(dǎo)管。當(dāng) 在零碎的基礎(chǔ)上且和現(xiàn)有的線路同行需要或預(yù)算許可時(shí)， 光纖可以提供額外的帶寬 。它比傳統(tǒng)的由熟悉的塑料護(hù)套包裝的光纖電纜更便宜。損壞的管道可以切去進(jìn)行修理，并且損壞的部分也可以用新的管替換它。T Premise Distribution System and the International Standards Organization39。 Voice/Data Wiring Closets The wiring closets are generally located on each floor of a bui buildings must be evaluated on a casebycase basis since some of the older buildings have limited space. For new buildings, each closet should be large enough to acmodate a minimum of two standard 19 puter racks. Each of the major premiseplans remends mounting electronics in 19 racks. The larger electronic ponents will require full frame puter racks. These racks will support the ISDN, Ether and Token Ring ponents. In addition, cross connection panels will be required for the telephone wiring, terminal wiring, Ether connections and future Token Ring. Two separate sets of cross connection panels will be required. The data wires will terminate in one set of panels and the voice wires in will segregate functions and minimize confusiondue to two separate anizations maintaining the same set of wires.The data wires will be patched into the appropriate rackmounted data hardware (. 3274 controllers, Ether Bridge boxes, etc.) and the voice wires will be patched into the rackmounted voice hardware (where possible). However if needs change, the base wiring plant will be able to support either the voice or the data technology. Modular cross connection equipment provides easier longterm maintenance and reconfigurability. There are many configurations available from third party sources such as ModTap, Nevada Western and Ortronics. At this point, however, it is most likely that JHMI will go with an ATamp。s Law closely in the past but recently, it has shown evidence of an acceleration faster than that predicted by the law. Onegigabit data rates are available now and 10gigabit rates are predicted by 2021. Vertical LAN In any building distribution, the vertical work carries about 80% of the traffic. This part of a building local area work (LAN) is business critical but fortunately, it is relatively easy to make changes to it. Quite often, this part of the work is realised as optical fibre. At one time, the bandwidth offered by optical fibre was regarded as unlimited but that is not the case now. For example, at 1gigabit rates, there is a length limit of about 220m when using popular about 500m when using 50/125181。s vertical LAN, the horizontal work is very costly to upgrade. Installations always mean serious disruption to normal work for a building39。s length. These weak receive signals can be swamped by the unwanted coupled signal from the transmitter. To overe these difficulties, more has to be spent in the design of the transceiver hardware. The cost of these items will rise as bandwidth is increased. Category 6 cable has been developed in order to address some of these problems but, at the moment, no standards have been ratified. Apart from these fluid aspects of copper solutions, there are other factors regarding their choice that should be borne in mind. Perhaps the most important consideration is the rather low bandwidth improvement that category 6 cable will offer. The ever rising expectations of work bandwidth will soon overtake the Gbs1 theoretical through put that it may provide. The respite that it may give is likely to be short. There are further worries about its interoperability and its backward patibility with existing installations. Category 7 cable is still under development and many experts in the industry believe the Ramp。s that no solution is futureproof