Channel estimation method of TDS (Total Dissolved Solids)-OFDM (Orthogonal Frequency Division Multiplexing) system

Abstract

The invention discloses a channel estimation method of a TDS (Total Dissolved Solids)-OFDM (Orthogonal Frequency Division Multiplexing) system, belonging to technical field of information transmission. For accurately extracting an effective CIR (Committed Information Rate) from a result C (n) C(n) which is obtained by carrying out a slipping correlation calculation to on a baseband signal and a PN1c sequence, the channel estimation method disclosed by the invention comprises the following steps: firstly, adopting an iterative threshold detection (ITD) method to detect a large-amplitude component in the result C(n) and removing a pseudo peak from the C(n) during an iteration process; then, adopting a double-sliding window detection (DSW) algorithm to detect a small-amplitude CIR component; and finally, combining the two detected results. The realizing process of the channel estimation method is shown as figure 4, wherein the detected object C0 (n) of the double-sliding window contains the amplitude CIR component; h1 and a are CIR and h1 obtained by iterative threshold detection; b is CIR obtained by double-sliding window detection; and the sum of a, h1 and b is a channel impulse response CIR vector h1 for channel equalization. The channel estimation method disclosed by the invention is applied, so that the channel estimation precision is high, channel change can be quickly followedtracked, and performance of a receiver can be improved.

Description

technical field [0001] The invention belongs to the field of digital information transmission, in particular to a channel estimation method for TDS-OFDM system. Background technique [0002] Time Domain Synchronous Orthogonal Frequency Division Multiplexing (TDS-OFDM) is a broadband wireless transmission technology adopted by my country's terrestrial digital television broadcast transmission (DTMB) standard (GB20600-2006). Unlike the CP-OFDM system based on CP (Cyclic Prefix, cyclic prefix), the TDS-OFDM system does not insert pilot symbols into subcarriers in the frequency domain, but in the time domain Orthogonal Frequency Division Multiplexing (OFDM) A PN sequence (pseudo-random sequence) is inserted between symbols as a guard interval, so the TDS-OFDM system can only do synchronization and channel estimation based on the PN sequence. The DTMB standard defines three frame header modes: frame header mode 1 (PN420), frame header mode 2 (PN595), and frame header mode 3 (PN9...

AI Technical Summary

Problems solved by technology

[0004] see figure 1 , the traditional channel estimation methods of TDS-OFDM mainly include: (1) Circular correlation based on PN sequence, because it only fixedly intercepts L from the received signal m The length of the baseband symbol, so the multipath information with a relatively long delay cannot be detected; (2) The frequency domain PN transformation method, which intercepts twice the frame header length (2*L FH ) data, and then use the discrete Fourier transform (DFT) / inverse discrete Fourier transform (IDFT) to obtain the channel impulse response (CIR). Since the intercepted data contains frame-body OFDM symbol components, so in a short time Severe Inter-Symbol Interference (ISI) will also be suffered under extended multi-path channels; (3) Based on the received baseband signal and PN lc After the sliding correlation operation is performed on the sequence, the result of the sliding correlation operation C(n) is detected by iterative threshold detection ITD to realize the detection of the channel impulse response CIR, but there is a missing detection of the low-power multipath component

Images