Research Of Channel Estimation In Wireless OFDM System

Along with development and improvement of society, many researchers pay much attention to developing system of wireless broadband digital communication. In wireless broadband digital communication, Inter-Symbol Interference (ISI) caused by time disperse of radio channel is one of main factors that limit bandwidth of communicated information and system performance of communication. In receiver, Orthogonal Frequency Division Multiplexing (OFDM) system can easily cancel ISI and equalize frequency-selective fadings that are both caused by time disperse of radio channel. For this, the research aiming to apply OFDM to system of wireless broadband digital communication had received more and more attention in recent years. In system of wireless broadband digital communication based on OFDM, receiver must acquire Channel Status Information (CSI) to equalize frequency-selective fading and implement decoding of Space-Time Code (STC). This paper did some investigations on channel estimation of wireless OFDM system, and achieved the following result and innovation:(1) This paper pays much attention to the character of LS algorithm's result in time-domain. At the same time, we take the character of wireless Channel Impulse Response (CIR) in time-domain into account. Then we propose to detect energy of CIR's tap in LS algorithm's result in time-domain and search the effective order of wireless channel conversely. And we gave out decision criteria and decision threshold. By theoretical analyses and computer simulation, it is indicated that this algorithm shows good performance in estimating effective order of radio channel.(2) A new kind of OFDM system is introduced without time-domain Cyclic Prefix (CP) and frequency-domain Pilot tones in mobile video broadcasting system, SMCC-plus, which is key innovation of SMCC-plus. Based on the time-domain signal structure of this OFDM system, an algorithm is proposed, by which SMCC-plus carries out channel estimation and tracking CSI. By theoretical analysis and computer simulation, it is...