In september 1999, the IEEE approved a new designation, known as 802.11.intended to retain the error-correction,security, powermanagement and other advantages of the original, a key ingredient-a thchnique for increasing bandwidth to 11M bit/sec.
Called complementary code keying(CCK)the technique works only in conjunction with the DSSS technology sprcified in the original standard . it does net work with frequency-hopping or infrared transmissions.
What CCK does is apply sophisticated mathematical formulas to the DSSS codes, a permitting the code to represent a greater volume of informitter is now able to send multiple bits of information with each DSSS code, enough to make possible the 11M bit /sec in the original standard .
The 802.11b standard benefits users by delivering wireless ethernet speeds of 11M bit/sec that can reliably support everyday business applications, e-mail, internet and server network access.
With support from the new wireless ethernet from the new wireless ethernet compatibility alliance, founded by 3com, lucent, nokia and several other companies in the wireless LAN business, the new standard will also promise certified interoperability across multivendor platforms.
Finally, the 802.11b standard serves as a clamoring for a simplified wireless LAN landscpape.
Vendors can now focus on a single, high-speed standard, and users can cut through the clutter of wireless options by fovusing on a standard that delivers multibvendor interoperability and the performance to meet their application needs.
1999年9月,IEEE批准了称作802.11B的新名称,作为802.11的高速扩展。此新的802.11B标准在保留原标准的纠错、安全、电源管理和其他优点的情况下,增加了一项关键内容,即把带宽增加到11兆位/秒的技术。
此项技术叫做互补码键控(CCK),他只与原标准中规定的直接顺序扩频(DSSS)技术一起工作,不能用跳频或红外线传输方式工作。
CCK所做的工作是把复杂的数学公式应用于DSSS代码,以允许该代码在每个时钟周期表示更多的信息。现在发射机能在每个DSSS代码中发送多个信息位,足以实现每秒11兆位/秒的数据传输率,而不是原标准的2兆位/秒。
802.11B 标准给出11兆位/秒的无线以太网速度,给用户带来好处,速度能可靠地支持日常的业务应用、电子邮件、因特网和服务器网络的接入。
由3COM、LUCENT、NOKIA和其他几家有无线局域网业务的公司组成的“无线以太网兼容性联盟”支持新的标准,此标准也有望实现跨多厂商与用户团结起来的作用。
现在,厂商能专注在单一的高速标准上,用户也能以通过关注给出厂商互用性和性能。以满足他们应用要求的标准上,解决了从一大堆无线网中作选择的难题。(全文完)
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