sofdma what is
Scalable OFDMA is the OFDMA Mode used in mobile WiMAX. It adds scalability to OFDMA. Scalability is supported by adjusting the size of FFT size while fixing the sub-carrier frequency spacing to 10.94kHz. It supports channel bandwidths ranging from 1.25 MHz to 20MHz.
Smaller FFT size is given to lower bandwidth channels, while larger FFT size to wider channels. By making the sub-carrier frequency constant, SOFDMA reduces system complexity of smaller channels and improves the performance of wider channels. This is where the difference comes between OFDMA and scalable OFDMA (Both use OFDM as the underlying modulation scheme ).