Akademik Veri Yönetim Sistemi
SIGMA JOURNAL OF ENGINEERING AND NATURAL SCIENCES-SIGMA MUHENDISLIK VE FEN BILIMLERI DERGISI, cilt.29, sa.2, ss.97-110, 2011 (ESCI)
In order to alleviate the effect of frequency selective channel a guard interval can be used. System performance varies depending on guard interval. In previous works, guard interval is associated with root mean square delay spread of the channel (rms) and the symbol duration. This paper investigates the sensitivity of Multi Carrier Code Division Multiple Access (MC-CDMA) performance to guard interval and demonstrates a novel approach to determine optimum guard interval. System performance is determined from the Signal to Noise Ratio (SNR) level of a detected bit. Analytical expressions for useful power, interference power and the signal to noise ratio at the detector output of the MC-CDMA system is derived. The optimum guard interval for a given channel profile and system parameters is determined as the guard interval with maximum SNR. Unlike the previous studies, the optimum value for the guard interval was investigated for different Es/N0. We show that Es/N0 and the optimum guard interval are growing increasingly and the optimum guard interval is approximately equal to maximum delay spread for Es/N0=30 dB. Instead of all the values of Es/N0 between the 0-30 dB to show the general trend was determined for values the optimum guard interval. After, which channel parameters can be associated with calculating the best for the optimum guard interval was investigated. The optimum guard interval is not exact multiple of rms and the symbol duration for different channel profiles and Es/N0 values. We show that the optimum guard interval used depending on Es/N0 can be selected as the delay window that includes certain multipath power. With such a method with different frequency selective channel profile without the need for complex operations can be identified the optimum guard interval.