1.1.4 Emergence of Standards-Based Technology
In 1998, the Institute of Electrical and Electronics Engineers (IEEE) formed a group called 802.16 to develop a standard for what was called a wireless metropolitan area network, or wireless MAN. Originally, this group focused on developing solutions in the 10GHz to 66GHz band, with the primary application being delivering high-speed connections to businesses that could not obtain fiber. These systems, like LMDS, were conceived as being able to tap into fiber rings and to distribute that bandwidth through a point-to-multipoint configuration to LOS businesses. The IEEE 802.16 group produced a standard that was approved in December 2001. This standard, Wireless MAN-SC, specified a physical layer that used single-carrier modulation techniques and a media access control (MAC) layer with a burst time division multiplexing (TDM) structure that supported both frequency division duplexing (FDD) and time division duplexing (TDD).
After completing this standard, the group started work on extending and modifying it to work in both licensed and license-exempt frequencies in the 2GHz to 11GHz range, which would enable NLOS deployments. This amendment, IEEE 802.16a, was completed in 2003, with OFDM schemes added as part of the physical layer for supporting deployment in multipath environments. By this time, OFDM had established itself as a method of choice for dealing with multipath for broadband and was already part of the revised IEEE 802.11 standards. Besides the OFDM physical layers, 802.16a also specified additional MAC-layer options, including support for orthogonal frequency division multiple access (OFDMA).
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