A Novel Iterative Decision-Directed Differential Detection Technique for Differential OFDM Systems

We propose a novel iterative decision-directed differential detection (iD⁴) technique for orthogonal frequency division multiplexing (OFDM) systems employing differential phase shift keying (DPSK) modulation in each subcarrier, such as the Eureka 147 digital audio/multimedia broadcasting (DAB/DMB) system. The iD⁴ technique improves the differential detection performance in fast fading channels by estimating and compensating the time-domain channel phase variation (CPV). Computer simulations show that significant performance improvement is achieved by using iD⁴ over conventional differential detection (CDD), and the maximum Doppler spread, at which the OFDM receiver can achieve satisfactory reception, is greatly extended. Taking the DAB/DMB system operating in mode IV at L-band as an example, iD⁴ increases the maximum receiver vehicle speed from 95 kilometers per hour (km/h) to 190 km/h, in a typical urban (TU) channel environment.