The performance of sequential decoding of long constraint length convolutional codes is evaluated for Rayleigh fading channels. Sequential decoding is not practical below a certain theoretical signal-to-noise ratio, and these theoretical limits are calculated for a number of modulation methods and code rates. As an example, with BPSK modulation, soft decisions and code rate 1/2, the theoretical...

A progressive method for transmission of images over a bursty noise hannel is presented. It is based on dis rete wavelet transform (DWT) oding and hannel-optimized s alar quantization. The main advantage of the proposed system is that it exploits the hannel memory and hen e has superior performan e over a similar s heme designed for the equivalent memoryless hannel through the use of hannel int...

In order to combat transmission errors in digital communication systems, forward error protection based on convolutional codes and interleaving in conjunction with soft decision maximum-likelihood decoding through the Viterbi algorithm is often applied. The expected bit error rate for a given signal-to-noise ratio is generally difficult to foresee for a certain system. In this paper, we introdu...

We analytically compare the word error probabilities of imperfectly symboland bit-interleaved block codes over GF(2m) on fading channels. We employ an approximate fading channel model of a two-state Markov chain, using statistics of the fadeand interfadedurations. The analytical method is based on a technique developed in [2]. Expressions are derived for two decoding strategies; independent bou...

Interleaving is a mechanism universally used in wireless access technologies to alleviate the effect of channel correlation. In spite of its wide adoption, to the best of our knowledge, there are no analytical models proposed so far. In this paper we fill this void proposing three different models of interleaving. Two of these models are based on numerical algorithms while one of them allows fo...

We consider several aspects of delay diversity in coded OFDM. The cyclic properties of the FFT allow to do delay diversity in a cyclic manner without exceeding the guard interval. We investigate the impact of different cyclic delays in terms of achievable diversity level, information theory and BER performance. Furthermore, we propose an interleaving and user assignment strategy which allows mu...

The new hash function DIHA2 (Dynamic Input Hash Algorithm)is with the structure of Merkle-Damgard and is based on 64-bit computing.It operates each 1024-bit block and outputts a 256-bit hash-value. For a 64-bit sub-block X[j](0 ≤ j ≤ 15) of each step, DIHA2 gets a dynamic mapping value of TLU (table look up,The table was 256-Byte only)and add it to operation of variables a, b, c, d,so as to eli...

It’s known that the bit errors of polar codes with successive cancellation (SC) decoding are coupled. However, existing concatenation schemes of polar codes with other error correction codes rarely take this coupling effect into consideration. To achieve a better BER performance, a concatenation scheme, which divides all Nl bits in a LDPC block into Nl polar blocks to completely de-correlate th...

We demonstrate six-channel 160-Gb/s wavelength-division-multiplexed transmission over 20 100-km spans of nonzero-dispersion fiber, with a spectral efficiency of 0.53 b/s/Hz. We achieve this result using optical-time-division multiplexing with polarization bit interleaving and return-to-zero differential-phase-shift-keying modulation format. We also operate at 170.6 Gb/s per channel to emulate t...

We consider the scenario of using Automatic Repeat reQuest (ARQ) retransmission for two-way low-bit-rate video communications over wireless Rayleigh fading channels. Low-delay constraint may require that a corrupted retransmitted packet not be retransmitted again, and thus there will be packet errors at the decoder which results in video quality degradation. In this paper, we propose a scheme t...