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After more than a year of work, the IEEE has ratified two updates to its 802.11 specification for wireless local-area network (WLAN) systems. The two updates, dubbed 802.11a and 802.11b, provide a roadmap for manufacturers to develop WLAN systems that deliver higher data rate operation.

The first, and more talked about standard, is the IEEE 802.11b specification. Also known as the high rate standard, this specification enables manufacturers to develop WLAN products that operate in the 2.4 GHz band and deliver 11 Mb/s data rates. This equates to a more than 5X performance increase over existing 802.11-compliant systems, which can deliver a maximum of 2 Mb/s.

To achieve these higher data rate levels, the 802.11b committee turned to a new modulation technique called complimentary code keying (CCK) (See IEEE Selects Harris/Lucent WLAN Proposal). This modulation technique was jointly developed Murray Hill, NJ-based Lucent Technologies and Melbourne, FL-based Intersil Corp (formerly Harris Semiconductor).

Al Petrick, vice chair of the 802.11 committee says this is a significant step for the IEEE. By ratifying the high rate standard, Petrick says the IEEE is providing WLAN developers with the means to develop systems that deliver Ethernet quality performance.

5 GHz Standard

During its last meeting, the IEEE 802.11 committee also ratified a specification put forth by its 802.11a task group. This group was formed to develop a physical layer specification for the upcoming development of WLAN systems operating in the 5 GHz ISM band.

The new specification is based around the use of a orthogonal frequency division multiplexing (OFDM) technique. By using this modulation scheme, engineers can develop WLAN product that sport data rates of 6 to 54 Mb/s.

One of the main benefits of the 802.11a physical layer specification is its similarity to the physical layer specification put forth by the ETSI-BRAN committee. According to Petrick, ETSI-BRAN has also designated OFDM as the modulation technique for WLAN products operating in the 5 GHz band. Therefore, ETSI's HIPERLAN II specification and the IEEE 802.11a specifications will feature essentially the same physical layer. Petrick says this will open worldwide development opportunities for WLAN system designers.

What's Next

Now that the high-rate specifications have been ratified, the 802.11 committee will now move on to other aspects of standards process. In particular, Petrick says the 802.11 committee will begin looking at issues such as isochronous operation, quality of service, and voice over IP (VoIP).

The IEEE 802.11 committee expects to deliver printed copies of the 802.11a and 802.11b standards by the end of this year. In addition, the association plans to release a handbook that outlines the existing and new high-rate
specifications.

Editor's Note:
For more information on trends in the WLAN market, visit Wireless Design Online's WLAN Beat column. In this column, Bruce Kraemer of Intersil Corp. highlights the main issues and topics shaping the WLAN industry.