The backward direction Soft Output Viterbi Algorithm (a backward SOVA) is compared with the conventional SOVA (a forward SOVA) in turbo code decoding. We find noticeable performance improvement for the backward SOVA when it is not terminated, which turns out to be due to a smaller reliability value, indicating that the termination conditions of the turbo encoder strongly affect the performance ...

This paper presents a cross layer iterative decoder for irregular Low-Density Parity-Check (LDPC) coded system by using Cyclic Redundancy Check (CRC) codes. The key idea of the decoder is to use the correctly decoded frame to help correcting the left erroneous ones. To accomplish this, the decoder digs the useful information between layers by using the cross layer design method and an iterative...

Most versions of the Peterson-Gorenstein-Zierler (PGZ) decoding algorithm are not true bounded distance decoding algorithms in the sense that when a received vector is not in the decoding sphere of any codeword, the algorithm does not always declare a decoding failure. For a t-error-correcting BCH code, if the received vector is at distance i, i t, from a codeword in a supercode with BCH distan...

The MPEG-4 video coding standard uses variable length codes (VLCs) to encode the indices of intra and inter macroblocks after discrete cosine transform and quantization. Although VLCs can achieve good compression, they are very sensitive to channel errors. Joint source-channel decoding (JSCD) is emerging as an efficient method for dealing with this sensitivity to channel errors. This paper prop...

The key issue of applying Turbo codes is to find an efficient implementation of turbo decoder. This paper addresses the implementation of a simplified and efficient turbo decoder in field programmable gate array (FPGA) technology. A simplified and efficient implementation of a Turbo decoder with minor performance loss has been proposed. An integer Turbo decoder based on the standard 2’s complem...

Hossam M. H. Shalaby University of Alexandria Department of Electrical Engineering Abstract. An optical dynamic spectral encoding code division multiple access CDMA communication system is proposed. In this system, an electrically controlled tunable optical filter TOF is used to encode the modulated broadband light source. The code depends on the function set to the controller. Two-dimensional ...

All-optical 4-bit Gray code to binary coded decimal (BCD) converter was demonstrated, for the first time in our knowledge, with the number of 12 SOAs by means of commercially available numerical analysis tool (VPI). Circuit design approach was modified appropriately in order to fit the electrical method on an all-optical logic circuit based on cross gain modulation (XGM) process so that signal ...

This paper proposes an all-fiber fast optical frequency-hop code division multiple access (FFH-CDMA) for high-bandwidth communications. The system does not require an optical frequency synthesizer, allowing high communication bit rates. Encoding and decoding are passively achieved by strain-tunable fiber Bragg gratings. Multiple Bragg gratings replace a frequency synthesizer, achieving a hoppin...

Sensory information is encoded in the response of neuronal populations. How might this information be decoded by downstream neurons? Here we analyzed the responses of simultaneously recorded barrel cortex neurons to sinusoidal vibrations of varying amplitudes preceded by three adapting stimuli of 0, 6 and 12 µm in amplitude. Using the framework of signal detection theory, we quantified the perf...

The use of block codes is a well known error-control technique for reliable transmission of digital information over noisy communication channels. However, a practically implementable softinput soft-output (SISO) decoding algorithm for block codes is still a challenging problem. This thesis examines a new decoding scheme based on the soft-output Viterbi algorithm (SOVA) applied to a sectionaliz...