Abstract
In orthogonal frequency division multiplexing (OFDM) system, the existence of frequency offset in AWGN channel affects the orthogonality among the subcarriers and consequently introduces the intercarrier interference (ICI). The paper investigates new ICI self-cancellation technique to mitigate the effect of ICI in FFT-OFDM and compares it to DCT based OFDM system in terms of bit error rate (BER) and carrier to interference ratio (CIR). The proposed method for group size three results in a significant 20 dB improved CIR in FFT-OFDM. In terms of BER, proposed ICI self-cancellation technique outperforms the other self-cancellation techniques in FFT-OFDM. Also, this paper investigates outperforming BER and CIR improvement by using DCT-OFDM without applying self-cancellation techniques, due to its energy compaction property.
Highlights
Orthogonal frequency division multiplexing (OFDM) is a special form multicarrier (MC) that dates back to 1960s
In 1948, Shannon suggested that in frequency selective channel the highest data rate can be achieved by using a multicarrier (MC) system with an intensive set of subchannels and adapting transmission powers and data rates according to the signal to noise ratio (SNR) at different subchannels
In 1980, Peled and Ruiz proposed OFDM system with cyclic prefix [5]. In this the cyclic prefix is used to maintain the orthogonality among the subcarriers and this results in the reduction of intersymbol interference (ISI) and intercarrier interference (ICI)
Summary
Orthogonal frequency division multiplexing (OFDM) is a special form multicarrier (MC) that dates back to 1960s. In this technique one data symbol is mapped on two subcarriers at transmitter side and at receiver side these groups of subcarriers are combined so the effects of ICI on these subcarriers cancel each other This scheme is easy to implement but the bandwidth efficiency is reduced. The major problem in OFDM is its carrier frequency offset error between the transmitted and received signal due to the frequency mismatch between the local oscillator of the transmitter and the receiver or Doppler shift due to relative motion between the transmitter and receiver In this situation, the orthogonality among the subcarriers is no longer maintained that results in introduction of intercarrier interference (ICI) in OFDM, and the performance of the system is degraded. An ICI self-cancellation scheme has been proposed, where one data symbol is mapped on three subcarriers which improves CIR and BER, while the bandwidth efficiency reduced by one third. Analysis of ICI in DCT-OFDM system is covered in Section 6; the last two sections produce simulation results and conclusion as Sections 7 and 8, respectively
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
