19-10-2012, 04:59 PM
USE OF MATLAB IN THE MULTICARRIER SIGNAL SENSING, OPTIMIZATION AND IMPLEMENTATION
USE OF MATLAB IN THE MULTICARRIER.pdf (Size: 187.93 KB / Downloads: 104)
Abstract
This contribution deals with the use of MATLAB in the area of the multicar-
rier communication systems, represented by the Orthogonal Frequency Division
Multiplexing (OFDM). The application of MATLAB to OFDM signal spectrum
sensing, optimization of subcarrier parameters and in the practical implementa-
tion is briefly described.
Introduction
Many of the current and future communication standards, like the WiFi, DVB-T/T2, WiMAX
or cognitive radio based IEEE 802.22 [1] use the principle of multicarrier communications. One
of the most widespread representatives of the multicarrier systems is the OFDM. The basic
structure of OFDM modulator is shown in Figure 1. The input data are divided into parallel
streams corresponding to individual subcarriers. The number of data subcarriers usually spans
from tens (48 in the case of IEEE 802.11a) to thousands (DVB-T/T2). The data on each
subcarrier are mapped according to selected constellation diagram (usually BPSK, QPSK or M-
QAM) and the OFDM modulation is implemented using the Fast Fourier Transform operation.
Use of MATLAB in OFDM signal DSP implementation
The last example illustrates the use of MATLAB for the verification of OFDM modulator im-
plementation in digital signal processor (C6713 Texas Instruments family). The modulator has
been implemented using C language according to the schematic from Figure 1. A signal pro-
cessing library DSPlib has been used. As the main part of the OFDM modulator consists of the
IFFT operation, the following C code is a heart of the implemented modulator