Coding Theory

Our research explores the relations among coding theory, information theory, and related areas of computer science and mathematics. In error control coding, our team is concerned with the design, performance analysis and decoding of efficient modern error control systems such as wavelet codes, rateless codes, low density parity check codes (LDPC) and other types of iterative coding schemes. We are particularly interested in coding techniques for erasure channels, unequal error protecting codes, rate compatible codes, nonuniform codes, and two-dimensional codes for digital communication/storage systems and wireless ad hoc networks.

 

 

LDPC Codes for Data Frames: Unequal Error Protection Using LDPC Codes

   

 

In many applications, especially multimedia applications, not all parts of data have equal importance. Therefore, it is desirable to have a coding scheme that provides unequal error protection (UEP). We proposed two schemes to construct LDPC codes that are suitable for UEP. The first scheme is based on partially-regular LDPC codes. The proposed ensemble for the second scheme is a combination of two conventional bipartite graphs. We derived density evolution formulas for both the proposed UEP-LDPC ensembles. Using the density evolution formulas, high performance UEP codes were found. The proposed codes were also shown to have linear encoding complexity, which is very desirable for practical applications.