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Development of A Recovery Algorithm for Sparse Signals based on Probabilistic Decoding

확률적 희소 신호 복원 알고리즘 개발

  • Seong, Jin-Taek (Department of Information and Communication Engineering, Honam University)
  • Received : 2017.09.27
  • Accepted : 2017.10.22
  • Published : 2017.10.30

Abstract

In this paper, we consider a framework of compressed sensing over finite fields. One measurement sample is obtained by an inner product of a row of a sensing matrix and a sparse signal vector. A recovery algorithm proposed in this study for sparse signals based probabilistic decoding is used to find a solution of compressed sensing. Until now compressed sensing theory has dealt with real-valued or complex-valued systems, but for the processing of the original real or complex signals, the loss of the information occurs from the discretization. The motivation of this work can be found in efforts to solve inverse problems for discrete signals. The framework proposed in this paper uses a parity-check matrix of low-density parity-check (LDPC) codes developed in coding theory as a sensing matrix. We develop a stochastic algorithm to reconstruct sparse signals over finite field. Unlike LDPC decoding, which is published in existing coding theory, we design an iterative algorithm using probability distribution of sparse signals. Through the proposed recovery algorithm, we achieve better reconstruction performance as the size of finite fields increases. Since the sensing matrix of compressed sensing shows good performance even in the low density matrix such as the parity-check matrix, it is expected to be actively used in applications considering discrete signals.

본 논문은 유한체(finite fields)에서 압축센싱(compressed sensing) 프레임워크를 살펴본다. 하나의 측정 샘플은 센싱행렬의 행과 희소 신호 벡터와의 내적으로 연산되며, 본 논문에서 제안하는 확률적 희소 신호 복원 알고리즘을 이용하여 그 압축센싱의 해를 찾고자 한다. 지금까지 압축센싱은 실수(real-valued)나 복소수(complex-valued) 평면에서 주로 연구되어 왔지만, 이와 같은 원신호를 처리하는 경우 이산화 과정으로 정보의 손실이 뒤따르게 된다. 이에 대한 연구배경은 이산(discrete) 신호에 대한 희소 신호를 복원하고자 하는 노력으로 이어지고 있다. 본 연구에서 제안하는 프레임워크는 센싱행렬로써 코딩 이론에서 사용된 LDPC(Low-Density Parity-Check) 코드의 패러티체크 행렬을 이용한다. 그리고 본 연구에서 제안한 확률적 복원 알고리즘을 이용하여 유한체의 희소 신호를 복원한다. 기존의 코딩 이론에서 발표한 LDPC 복호화와는 달리 본 논문에서는 희소 신호의 확률분포를 이용한 반복적 알고리즘을 제안한다. 그리고 개발된 복원 알고리즘을 통하여 우리는 유한체의 크기가 커질수록 복원 성능이 우수한 결과를 얻었다. 압축센싱의 센싱행렬이 LDPC 패러티체크 행렬과 같은 저밀도 행렬에서도 좋은 성능을 보여줌에 따라 이산 신호를 고려한 응용 분야에서 적극적으로 활용될 것으로 기대된다.

Keywords

References

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