Simple OFDM

Document Type


Publication Date

Summer 6-2010

Publication Source

Virginia Tech Summer School

Place of Publication

Blacksburg, VA


There is a significant demand for a decreasein the size, weight and power (SWaP) associated withwireless systems. In this research, a low-complexityMIMO OFDM system is advanced. The proposedsystem is essentially multiplierless and thus requiresmuch simpler digital hardware to be implemented. As aresult, the chip area associated with the MIMO OFDMsystem can be significantly reduced. The reduction incomplexity is obtained via modification to the FastFourier Transform (FFT) and Inverse Fast FourierTransform (IFFT) algorithms necessary to implementOFDM multi-carrier modulation. Computationalcomplexity is reduced by quantizing what are known asthe “twiddle factors” in traditional FFT algorithms suchas the Radix-4. The quantization allows for allmultiplications to be done with values of one, negativeone, zero or a value that is a power of two. Replacingstandard multiplications with trivial multiplicationssignificantly reduces the computational complexity andallows for a simple hardware implementation.Depending on the application, different quantizationlevels can be utilized in order to obtain the necessaryperformance characteristics. As more quantizationlevels are used, the system performance increasinglyapproaches the performance of a system that uses theconventional transforms.


OFDM, orthogonal transforms


Engineering | Signal Processing | Systems and Communications