The Research Of Fast Channel Estimation Using FWT In DMB-T Systems And Digital Design

Digital television terrestrial broadcasting (DTTB) is the hotspots in wireless communication field for the recent years. In the terrestrial broadcasting system, the synchronization of receiver's Pseudo-Noise(PN) code to the transmitter's PN code is such an important part that the whole system can't work at all without it. But the traditional method to capture the PN code is either too slow or too complicated to satisfy the need of today's communication system.On August 1 st, 2006, China published the standard of digital television terrestrial broadcasting system—DMB-T, and confirmed the transition period for one year. In DMB-T, a new modulation scheme called time domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) is used, which inserts PN sequences as the guard intervals instead of cyclic prefix (CP) in traditional OFDM. This method has better noise handling against multi-path effects and narrow-band interference.Based on the characteristics of pseudo-random code sequence, this paper proposes a new algorithm for channel estimation in DMB-T systems using FWT (Fast Walsh Transform), which is equivalent to sliding window method theoretically on performance. Interference cancellation is also implemented to further reduce the interference between different paths. This new algorithm uses butterfly operation in the matching process of PN sequence, and reduces the computational complexityfrom N² of traditional method to (N+1) log₂(N+1).At last, this paper proposes a digital design using minimum hardware resource, which minimized the design area and reduced the static power effectively. The new system is expected to be more feasible and practical due to the fact that the algorithm is fast and the computational complexity is low.