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主题： 请教 [] |
 发表于 2008/4/17 16:40:00
Stations can transfer data following one of several access mechanisms. A first access mechanism is known as carrier sense multiple access with collision avoidance (CSMA/CA) according to which a station senses the wireless medium before beginning a transmission. The station can either use a physical carrier sensing mechanism or, preferably, the station can use a virtual carrier sensing mechanism as provided in the IEEE 802.11 specification with the network allocation vector (NAV). Such access mechanism is also referred to as the distributed coordination function (DCF), which is a contention based channel access that all stations use when they compete for the medium. A second access mechanism is a centrally controlled one that uses a poll and response protocol to avoid collision and contention. This access mechanism is also called the Point Coordination Function and is managed by a Point Coordinator (PC) usually located in an access point (AP). Stations transmit requests to the PC that logs the requests in a polling list and polls the stations one after another for traffic while also delivering traffic to them. The PCF is the preferred access mechanism when time-sensitive multimedia content is transmitted over a crowded environment. The PCF may be used together with the distributed coordination function (DCF). 工作站采用下列访问机制传输数据。第一种称为载波侦听多点接入/避免冲撞（CSMA/CD）访问机制，工作站传输数据前通过它来监听网络无线介质是否占用。工作站使用物理载波监听或更多使用IEEE 802.11 规定中有网络分配向量(NAV)的虚拟载波监听。此访问机制也称为分布式协调功能(DCF)，它是所有工作站争用传输介质时使用的基于线路争用的信道。第二种是采用信包与响应协议的避免冲突与线路争用的中央访问机制。 此访问机制也称为点协调机制（PCF），由安装在接入点(AP)内的点协调器(PC)控制。工作站向点协调器发送指令，点协调器然后将该指令登陆到轮询表，并依次排定各工作站的流量，同时向其发送。 信道繁忙时传输限时性多媒体内容多采用点协调访问机制，它也可以和分布式协调访问机制联合使用。 上文是我的一份测试稿，请各位大仙指点一二。
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| Re. 发表于2008/4/22 17:10:00 多谢多谢。 我也通过了该测试，还望以后多多指教。我的联系方式：qq:464115827,msn:alan_liu68@hotmail.com
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| Re. 发表于2008/4/17 23:31:00 恰好我也前周做了他们的测试,一样的.是网络通讯方面的.我是通过了他们的测试,其实当时我知道,通过是肯定的.毕竟做这领域不少也赢得客户好评. 所以看了你的译文后就再熟悉不过了,整体看还是可以的.但个别专业性方面还不够理想.比如在网络协议中(SENSE)不翻译"监听",而是"帧听",还有到数第二句中的crowded entironment,不翻译成繁忙,而是复杂环境,也是在这句中的PREFERRED,不是多采用,而翻译成"首选"访问方式.等POINT很少说点协调访问机制,而是集中访问机智,等等，没太多时间一一列举了,这些就是专业性强点的,多留意下就好了.
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