Cascading Hadamard code-aided carrier synchronization method under extremely low signal to noise ratio (SNR)

An auxiliary synchronization and auxiliary carrier technology, applied in the field of wireless communication, can solve problems such as unsatisfactory synchronization performance, and achieve the effect of auxiliary estimation range

Inactive Publication Date: 2011-06-29
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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Problems solved by technology

In the case of extremely low signal-to-noise ratio, pure LDPC or Turbo codes can no longer meet the requirements of synchronization performance

Method used

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  • Cascading Hadamard code-aided carrier synchronization method under extremely low signal to noise ratio (SNR)
  • Cascading Hadamard code-aided carrier synchronization method under extremely low signal to noise ratio (SNR)
  • Cascading Hadamard code-aided carrier synchronization method under extremely low signal to noise ratio (SNR)

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Embodiment Construction

[0022] The present invention will be further described below in conjunction with the drawings.

[0023] The present invention further expands the scope of synchronization on the basis of coding assisted synchronization in an extremely low signal-to-noise ratio environment to adapt to more application environments. Taking advantage of the unique advantages of channel coding LDPC-Hadamard codes, first perform Hadamard search at the receiving end to determine the frequency offset range of the coarse step, and then perform compensation, and then perform further synchronization under the compensated information for better interpretation. code.

[0024] The technical scheme of the present invention includes the following steps:

[0025] Step 1: The sender first performs LDPC-Hadamard coding on the information bits (the code length is set to N d ), and then add pilot symbols according to the PMP (Pre-Mid-Postamble) structure assuming that the pilot length is (N p ), then perform BPSK modul...

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Abstract

The invention provides a cascading Hadamard code-aided iterative carrier synchronization scheme under an environment with an extremely low signal to noise ratio (SNR). By using the scheme, even under the environment with an extremely low SNR, accurate synchronization and correct decoding can be realized, and more importantly, the synchronization range is enlarged. In the invention, a transmittingend and a receiving end are utilized. The transmitting end is used for coding low density parity check (LDPC)-Hadamard cascading codes and adding pilot frequency. At the receiving end, different fromthe conventional simple pilot frequency unicode-aided carrier method, the method provided by the invention comprises the following steps: firstly, carrying out Hadamard code related search by using the orthogonality of Hadamard codes to pre-estimate a wide range of frequency offset and compensate the frequency offset, thus the frequency offset is greatly compensated in the process; secondly, extracting the pilot frequency of the compensated information for coarsely synchronizing; carrying out fine synchronization by utilizing the ideas of decoding iteration and maximum likelihood; and finally, carrying out decoding judgment.

Description

Technical field [0001] The present invention belongs to the field of wireless communication technology, and relates to channel coding and carrier synchronization technology in wireless communication. Background technique [0002] Error-correcting codes with strong error correction capabilities, such as Turbo codes and LDPC codes, have excellent theoretical performance, and there are often large gaps in performance in practical applications. This is mainly due to the reduction of system synchronization accuracy as the signal-to-noise ratio decreases. In the case of extremely low signal-to-noise ratio, simple LDPC or Turbo codes can no longer meet the requirements of synchronization performance. [0003] Carrier synchronization technology has a wide range of applications in the fields of radio navigation, positioning, remote sensing and telemetry, and it is one of the problems that must be solved in the reception of communication signals. In recent years, a code-assisted iterative c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L1/00H04L27/26H04L25/02
Inventor 史治平龚万春唐发建
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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