Abstract:
The rapid advancement in the field of wireless communications that
has been expedited by the commercial demand for better services has led to
the application of wireless systems in many fields of life including
education, military, medical and many real time services. A number of these
services demand a high data rate for the applications to run. OFDM is a
promising technique that can provide this high data rate by efficiently
utilizing the available bandwidth. The problem with this technique is the
high Inter-Carrier Interference that occurs due to the disturbance of
orthogonality between the subcarriers of an OFDM symbol during the
course of transmission. This requires a better channel estimation strategy.
Alongwith this, despite the fact that most of the emerging wireless standards
such as 802.11n (Wi-Fi) and 802.16e (WiMax) use OFDM technique for
increased spectral efficiency and improvement of performance, very little
attention has been paid to the use of efficient error correcting Turbo codes ithese systems. The BER of the published work is still not better than 10-3 at
affordable SNR for lower modulation schemes.
In this research we have applied Frequency-domain equalization
technique for suppressing ICI in the OFDM system and have integrated
Turbo Codes in the resulting system for error correction. We have worked
on the design of an efficient encoder and decoder. The decoder uses an
iterative mechanism for decoding the received bits that is based on
Maximum a posteriori algorithm. The error reduction achieved by the
iterative mechanism of the Turbo Decoder improves the overall coding gain
of the system. Results have been achieved for a number of lower order
modulation schemes through MATLAB simulation with and without Turbo
Codes implementation and with the application of Frequency-domain
equalization strategy
