Convolutional Codes have been widely used to provide
powerful error control capability to reduce bit error rate (BER)
performance in digital communications system.
Customarily the encoder adopts zero-tail. In this method, the
encoded codewords have better protection to resist noise but this
scheme will produce additional tail bits. Tail bit will reduce the
code rate and affect transmission efficiency, especially, when
message length is very shorter such as headers. Many literatures
proposed other methods to improve the code rate loss due to adopt
zero-tails. Among them, the tail-biting Convolutional Code scheme is
the most widely adopted to keep well error control capability in
error control coding. Recently the
tail-biting Convolutional Code has been used in digital
communications systems, such as IEEE 802.16 WiMAX system.
Due to the decoding complexity of the tail-biting Convolutional Code
that is more complicated than that of zero-tail scheme, the
tail-biting Convolutional Code does not use optimal decoding
algorithm solution such that the decoding complexity can be reduced to
In this proposal we focus on two aspects. We first proposed a new suboptimal
decoding algorithm that perform on a proposed newly trellis such that the decoding complexity can be reduced drastically.
Furthermore, we will also propose an optimal bidirectional decoding algorithm that decodes the received vector
simultaneously from start nodes and end nodes. Lower decoding complexity can be expected by this bidirectional