Plenary lecture I: influence of segmentation to efficiency of joint channel coding and cryptography
Natasa S. Zivic · 2008
Newly researches show that cooperation between the elements of the receiver improves the accuracy of the received information. Such cooperation is especially important in noisy environments, as wireless, mobile and satellite communications. Examples of cooperate work of elements of receiver are: 1. iterative decoding with feedback used inside of the channel decoder for Turbo codes in order to decrease the error rate 2. the feedback information about the decoded bits from the channel decoder to the demodulator used to improve the equalization and synchronization of the demodulator 3. the feedback information from the source decoder to the channel decoder used to improve the channel decoding (so-called source channel decoding). Joint Channel Coding and Cryptography represents the combination of cryptography and convolutional channel coding. SISO channel decoder and decryptor exchange output information with each other, enabling correction of the output results. This cooperation introduces feedback from decryptor to the SISO decoder for sending information which helps correction of results. The algorithm of Joint Channel Coding and Cryptography is based on the use of L-values (reliability values) which are output of the SISO channel decoder and input to the decryptor. L-values show the probability of wrong decoded bits of the received information. Therefore absolute L-values are ordered per their greatness, for correction of bits with the lowest absolute L-values which have the highest probability of being wrong decoded. Joint Channel Coding and Cryptography uses feedback for improving of decoding results using the information previously corrected by the lowest absolute L-values. Efficiency of the feedback, depending on the lengths of information which have to be corrected, is the subject of this lecture.