TY - GEN
T1 - Time varying convolutional codes revisited
AU - Pérez, Lance C.
N1 - Publisher Copyright:
© 2001 IEEE.
PY - 2001
Y1 - 2001
N2 - There are several cases where the maximum free distance (MFD) time-invariant convolutional code of a given rate and total encoder memory does not meet the Heller bound or where the encoder that does meet the Heller bound is catastrophic. In order to find codes that meet the Heller bound, it is sometimes necessary to use time-varying convolutional codes. Some periodic time-varying convolutional codes with free distance greater than the best known time-invariant code of the same rate and total encoder memory are presented. These codes also achieve the Heller bound for the given code parameters. In addition, the use of time-varying encoders in order to achieve "spectral thinning" is explored.
AB - There are several cases where the maximum free distance (MFD) time-invariant convolutional code of a given rate and total encoder memory does not meet the Heller bound or where the encoder that does meet the Heller bound is catastrophic. In order to find codes that meet the Heller bound, it is sometimes necessary to use time-varying convolutional codes. Some periodic time-varying convolutional codes with free distance greater than the best known time-invariant code of the same rate and total encoder memory are presented. These codes also achieve the Heller bound for the given code parameters. In addition, the use of time-varying encoders in order to achieve "spectral thinning" is explored.
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U2 - 10.1109/ITW.2001.955138
DO - 10.1109/ITW.2001.955138
M3 - Conference contribution
AN - SCOPUS:39049108597
T3 - Proceedings - 2001 IEEE Information Theory Workshop, ITW 2001
SP - 67
EP - 69
BT - Proceedings - 2001 IEEE Information Theory Workshop, ITW 2001
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 2001 IEEE Information Theory Workshop, ITW 2001
Y2 - 2 September 2001 through 7 September 2001
ER -