嶄猟
       
FTTH Terminal Box
Field Assembly connector
EPON system
Fiber Switch
SFP Transceiver
Media Converter
PDH Multiplexer
Optical Automatic Protect
DWDM/CWDM/OADM
PLC Splitter
Coupler
Optical Circulator
Optical Isolator
Optical Switch
Patch Cord/Connector
Optical Adaptor
Optical Attenuator
Patch Panel
Fiber Optic Closure
In-door Terminal Box
Optical Distribution Frame
FTTH Drop Cable
Optical Cable

 
 
Solution
 
#New Wireless LAN Standard
With portable computers and wireless LANs, users can enjoy greater productivity while away from their desks, whether they are in conference rooms, public areas remotes offices.
Until recently, however, wireless LANs were too slow for most enterprise applications. Based on the IEEE802.11 standard, they ran at 1M to 2M bit/sec.
Now a new high--rate extension to the standard, 802.11b, lets wireless networks support data rates up to 11M bit/sec.
Ratified in 1997, the original 802.11 standard united the wireless industry by defining a low--level protocol architecture that worked with conventional upper--layer enterprise protocol stacks. Also, 802.11 maintained compatibility with the three most popular radio transmission types: direct sequence spread spectrum, frequency--hopping spread spectrum, and infrared.
Essentially, this new architecture added intelligence at the medium access control (MAC) Layer 2 and at the physical (PHY) Layer 1,fostering cooperation between the two layers in performing the critical tasks involved with initiating and maintaining wireless communications.
For instance, to ensure reliability of the wireless link, the MAC and PHY work together to determine if a clear path exists before they start a transmission.
During transmission, they employ special collision!avoidance and arrival!acknowledgement techniques that are not required in wired Ethernet LANs.
In September 1999, the IEEE approved a new designation, known as 802.11. Intended to retain the error!correction, security, power-management and other advantages of the original, the new 802.11b standard adds a key ingredient!a technique for increasing bandwidth to 11M bit/sec.
Called Complementary Code Keying (CCK) the technique works only in conjunction with the DSSS technology specified in the original standard. It does not work with frequency!hopping or infrared transmissions.
What CCK does is apply sophisticated mathematical formulas to the DSSS codes, permitting the codes to represent a greater volume of information per clock cycle. The transmitter is now able to send multiple bits of information with each DSSS code., enough t make possible the 11M bit/sec of data rather than the 2M 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, email, Internet and server network access.
With support from the new Wireless Ethernet Compatibility Alliance, founded by 3Coom, 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 as a rallying point for vendors and users clamoring for a simplified wireless LAN landscape.
Vendors can now focus on a single, high-speed standard, and users can cut through the clutter of wireless options by focusing on a standard that delivers multivendor interoperability and the performance to meet their application needs.
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