Punctured Turbo Codes for Bandwidth-efficient Transmission

Turbo codes are the error-coding schemes applied nowadays in wireless networks. In navalapplications, the information is mostly sent through wireless networks and the data is moreprone to noise. Since very important data has to be communicated, it is necessary to get backthe original data in the receiver. In military applications also, the soldiers wear electronic jacketswhich are connected by wireless networks. In such applications, the data loss is not affordableand there is also a need to utilise the bandwidth efficiently through puncturing by means ofwhich certain bits are deleted before transmission from the output of encoder. By means of thispunctured turbo codes, bandwidth-efficient coding is achieved. Hence, it is necessary to designturbo codes with an efficient puncturing pattern so that the performance of the punctured codeis also improved in spite of deletion of few bits before transmission. This paper deals in choosingthe 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 puncturingpatterns is based on the minimum weight of code words and their multiplicities. The best puncturingpattern chosen is tested for its performance by simulating turbo codes for an additive whiteGaussian noise (AWGN ) channel. Compared with the existing puncturing pattern, the patternproposed is able to achieve a gain of 0.5 dB at a bit-error rate of 10-3