The concept of scalability was introduced to the IEEE
802.16 WirelessMAN Orthogonal Frequency Division
Multiplexing Access (OFDMA) mode by the 802.16 Task
Group e (TGe). A scalable physical layer enables
standard-based solutions to deliver optimum performance
in channel bandwidths ranging from 1.25 MHz to 20
MHz with fixed subcarrier spacing for both fixed and
portable/mobile usage models, while keeping the product
cost low. The architecture is based on a scalable
subchannelization structure with variable Fast Fourier
Transform (FFT) sizes according to the channel
bandwidth. In addition to variable FFT sizes, the
specification supports other features such as Advanced
Modulation and Coding (AMC) subchannels, Hybrid
Automatic Repeat Request (H-ARQ), high-efficiency
uplink subchannel structures, Multiple-Input-MultipleOutput
(MIMO) diversity, and coverage enhancing safety
channels, as well as other OFDMA default features such
as different subcarrier allocations and diversity schemes.
The purpose of this paper is to provide a brief tutorial on
the IEEE 802.16 WirelessMAN OFDMA with an
emphasis on scalable OFDMA.