Determination of the Optimum Guard Interval for an MC-CDMA system using measurement-based channel models

Frequency selective channel distortions in the Multi Carrier Code Division Multiple Access (MC-CDMA) system is reduced with the use of guard interval. In previous works, guard interval is associated with root mean square delay spread of the channel (τ_rms) and the symbol duration. This paper investigates the sensitivity of MC-CDMA performance to guard interval and demonstrates a novel approach to determine the Optimum Guard Interval (OGI). System performance is determined from the Signal to Noise Ratio (SNR) level of a detected bit. The OGI for a given channel profile and system parameters is determined as the guard interval with maximum SNR. Unlike the previous studies, the OGI was investigated for different E_s/N₀. The OGI are growing increasingly with E_s/N₀ and is equal to maximum delay spread for E_s/N₀=30dB. We show that the OGI used depending on E_s/N₀ can be selected as the delay window that includes certain multipath power. With such a method with different frequency selective channel profile the optimum guard interval without the need for complex operations can be identified.