jaeyeon302 / Blind-estimation-Of-encoder-interleaver

Implementation of Blind Estimation of Encoder and Interleaver Characteristics in a Non Cooperative Context

Implementation of Blind estimation of encoder and interleaver Characteristics

Introduction

This code is implementation of blind estimation of encoder and interleaver characteristics.
The purpose of this Implementation is to find out the coderate of encoder and period of interleaver.

Example

example.py shows how it works. it uses hamming74 encoder and block interleaver that Each is implemented in toyEncoder.py and toyInterleaver.py to test.

How it works

Basic Idea is to reduce the rank of matrix that filled by unknown bitstream by syncing interleaving period.

1. make matrix(called Z) which is filled by unknown bitstream. the size of Z is n by m. (n = period, m > n).
2. when n is the multiple of real interleaving period, the rank of Z is will be reduce radically. if we define rho as rank(Z) over n, rho will be radically reduced. In other cases, rho will be maintained around 1.
3. if we sync the first bit where interleaving start, rho is converged to coderate. (it will be minimum value.)

• estimtateInterleavingPeriod(bits,maxPeriod) in operation.py
  : it checks rhos by making Z matrix in each period under maxPeriod.
• estimateCoderate(bits,period) in operation.py
  : it finds the number of bits to skip and estimated coderate under assumption that period is real interleaving period.

Reference

Blind Estimation of Encoder and Interleaver Characteristics in a Non Cooperative Context
(Gilles BUREL and Roland GAUTIER,2003)
(link : http://pagesperso.univ-brest.fr/~gburel/publis/Articles/post/2003_11_ciit_Interleaver.pdf)