Orthogonal Frequency-Division Multiplexing (OFDM) in GNU Radio

Pandi February 3, 2015 2 min read

Mobile communications systems revolutionized the way we communicate. A long way in a remarkably short time has been achieved in the history of wireless. Evolution of wireless access technologies is about to reach its fifth generation.

Looking past, wireless access technologies have followed different evolutionary paths. Very beginning we had 1G then 2G as time roles of 3G and now people are inclined towards 4G.

Each generations uses different technic to achieve higher data rates and to provide many value added features.

In this blog let’s look at Orthogonal Frequency-Division Multiple Access (OFDM) this multiple access is used in 4G. Let’s demonstrate an OFDM Technic with the help of blocks present in GNU Radio companion.

GNU Radio is an open source software tool that provides signal processing blocks to implement communication and signal system applications. And now we will discuss about how to carry out OFDMA.

Let’s understand concept of OFDM

OFDM is a form of multi-carrier modulation. An OFDM signal consists of a number of closely spaced modulated carriers. When modulation of any form – voice, data, etc. is applied to a carrier, then side-bands spread out either side. It is necessary for a receiver to be able to receive the whole signal to be able to successfully demodulate the data.

To carry out OFDM Technic in GNU Radio companion we need to use OFDM modulation block and for generation and visualization of waveform we use source and scope sink blocks.