Tds - Ofdm Systems Channel Estimation Algorithms And Logic Implementation

Orthogonal frequency division multiplexing (OFDM) has been a popular modulation scheme for wideband digital communication, whether wireless or over copper wires. Due to its high spectrum efficiency and superiority of resisting multipath channel echoes, TDS-OFDM is originally adopted by Chinese DTV standard DTMB, which is of great value to break through the patent barrier of CP-OFDM.Channel estimation (CE) is crucial to wireless communication. Its accuracy has a significant impact on the performance of receivers. However, conventional CE algorithms based on pilot symbols for CP-OFDM is not directly applicable to TDS-OFDM systems, since training sequences are only inserted in time domain.In this dissertation, based on analysis of potential challenges and basic CE algorithms for TDS-OFDM, different methods to reduce interference caused by frame body are investigated in detail. The main work is as follows:1. The effects of mutual interference between PN and OFDM symbol (ISI) and energy leakage of OFDM systems are examined at length.2. Conventional CE methods:circular correlation, moving correlation and frequency domain PN transformation are studied. And existing techniques to eliminate long-delay echoes are further discussed.3. An improved detection algorithm is derived for low-level CIR detection. And the detection performance is investigated theoretically and simulated. Experimental results verified the proposed scheme and the theoretical analysis.4. Accoding to the characteristics of ITD algorithm, a simplified ISI reduction algorithm without additional multipliers is developed, which is significant for hardware implementation.5. The FPGA implementation of CE is carried out. RTL coding, design rule checking, logic synthesis, placement and routing and timing analysis are executed. Finally, the RTL design is verified by co-simulation with SPD, an ESL design tool.