Punctured Turbo Codes Research Articles

Puncturing effects on turbo codes

The authors address various important issues related to punctured turbo codes. A modified technique for finding the transfer function of punctured turbo codes is developed. This modified technique provides a means of deterministic evaluation of the weight distribution of the code, as well as a possibility of studying various puncturing patterns. These advantages are shown with some illustrative examples. Moreover, the paper explains some characteristics of the puncturing pattern, and arrives at useful guidelines for the design of a good puncturing matrix.

Robust image transmission using JPEG2000 and turbo-codes

A method of combined source and channel coding is described that provides robustness to errors from a binary symmetric channel and uses the JPEG2000 (JP2) image compression standard. The source code rate and channel code rate are jointly optimized to produce a stream of fixed-size channel packets, such that the rate allocation complexity grows O(N/sup 2/) with the number of transmitted packets, N. Punctured turbo codes are used for channel coding, providing strong error protection. The rate allocation scheme presented obtains all necessary information from the JP2 encoder, and does not require image decompression.

Compression of correlated binary sources using turbo codes

We propose the use of punctured turbo codes for compression of correlated binary sources. Compression is achieved because of puncturing. The resulting performance is close to the theoretical limit provided by the Slepian-Wolf (1973) theorem. No information about the correlation between sources is required in the encoding process. The proposed source decoder utilizes iterative schemes, and performs well even when the correlation between the sources is not known in the decoder, since it can be estimated jointly with the iterative decoding process.

Turbo-SPC codes

This letter is concerned with a family of modified turbo-type codes, referred to as turbo-SPC (single parity check) codes. A technique based on the SPC code is introduced to replace puncturing for rate adjustment. A noticeable feature of the proposed scheme is the significantly reduced decoding complexity compared with the standard punctured turbo code. The cost reduction factor becomes more noticeable as rate increases (over ten times for rate /spl rarr/1). The error-rate floor problem known to turbo codes can also be improved using the proposed scheme. For moderate to high rates, performances of about 0.5 dB from the theoretical limits at BER=10/sup -5/ have been observed for turbo-SPC codes.

Approach for deriving performance bounds ofpunctured turbo codes

The average upper bound for punctured turbo codes is derived from knowledge of the conditional weight enumerating function of the original low-rate code. A novel approach to generating these bounds, hypergeometric puncturing, is introduced, which enables the performance to be averaged over all possible puncturing positions at a required code rate.