A Class Project On An Ldpc Based Error Correcting System

The low-density parity check (LDPC) code is an error correcting code that closely approaches the information theoretical channel limit, also called channel capacity. LDPC and Turbo codes are the only two currently known codes that are denominated capacity approaching codes, and are extensively used in communication systems requiring high capacity. It was only after several decades of research, sprung from Claude Shannon’s seminal work on the mathematics of communication theory, that a capacity approaching code was designed. Developing a capacity approaching code requires the knowledge of a large variety of different error correcting approaches, generally based on advanced mathematic skills. This knowledge typically is taught in classes dealing with coding theory, error correction codes, or information theory etc. Hence, LDPC codes are seldom taught in an undergraduate curriculum, as they are combined in graduate programs with other coding techniques. However, it has been recently found that LDPC code can be understood from factor graphs, which is a dramatically different approach as that used traditionally in coding theory classes. With the factor graph approach, it is possible for undergraduate students to have an introductory experience to error correcting codes in the LDPC family. This paper documents the findings resulting from a project done in a senior-level Digital Signal Processing (DSP) class. The successful class project proves that it is possible for undergraduate students to understand LDPC codes based on factor graphs, without any other traditional coding theory background.