Punctured Turbo Codes for Bandwidth-efficient Transmission

Abstract

Turbo codes are the error-coding schemes applied nowadays in wireless networks. In naval
applications, the information is mostly sent through wireless networks and the data is more
prone to noise. Since very important data has to be communicated, it is necessary to get back
the original data in the receiver. In military applications also, the soldiers wear electronic jackets
which are connected by wireless networks. In such applications, the data loss is not affordable
and there is also a need to utilise the bandwidth efficiently through puncturing by means of
which certain bits are deleted before transmission from the output of encoder. By means of this
punctured turbo codes, bandwidth-efficient coding is achieved. Hence, it is necessary to design
turbo codes with an efficient puncturing pattern so that the performance of the punctured code
is also improved in spite of deletion of few bits before transmission. This paper deals in choosing
the puncturing patterns that lead to systematic rate-compatible punctured turbo codes (RCPTCs)
which also give a reduction in bit-error rate. The design criterion for choosing the best puncturing
patterns is based on the minimum weight of code words and their multiplicities. The best puncturing
pattern chosen is tested for its performance by simulating turbo codes for an additive white
Gaussian noise (AWGN ) channel. Compared with the existing puncturing pattern, the pattern
proposed is able to achieve a gain of 0.5 dB at a bit-error rate of 10-3.