21-06-2012, 04:27 PM
An Experimental Study to Reduce the Effect of ICI in OFDM Based WLAN System
An Experimental Study to Reduce the Effect of ICI.pdf (Size: 565.86 KB / Downloads: 51)
Abstract
Orthogonal Frequency Division Multiplexing (OFDM), because of its resistance to multipath fading, has attracted increasing interest in recent years as a suitable modulation scheme for commercial high-speed broadband wireless communication systems. OFDM can provide large data rates with sufficient robustness to radio channel impairments. Orthogonal frequency division multiplexing (OFDM) is one of the Multi-Carrier Modulation (MCM) techniques that transmit signals through multiple carriers.
Introduction
Orthogonal Frequency Division Multiplexing is a special case of multi-carrier modulation and widely used in wireless communication system like wireless local area network and Digital Audio Broadcasting (DAB). However one of the problems in OFDM systems is its sensitivity to phase offset and frequency offset caused by Doppler frequency drift and multipath fading [1]. In such situations, the orthogonality of the carriers is no longer maintained, which results in Intercarrier Interference (ICI).
OFDM Transmitter
An inverse FFT is computed on each set of symbols, giving a set of complex time-domain samples. These samples are then quadrature-mixed to pass band in the standard way. The real and imaginary components are first converted to the analogue domain using digital-to-analogue converters (DACs); the analogue signals are then used to modulate cosine and sine waves at the carrier frequency, respectively. These signals are then summed to give the transmission signals.
Conclusion
Orthogonal Frequency Division Multiplexing (OFDM) is a very important modulation technique in wideband wireless communication and multimedia communication systems. The paper concentrates on reducing the effect of ICI using ICI self cancellation scheme and modified self cancellation scheme and comparing their result.