In this study, the coverage of downlink cellular orthogonal frequency‐division multiple‐access networks transmitting one quadrature‐amplitude modulation symbol per hop is analysed. The coverage probability is first defined by using an upper bound on the bit error rate (BER) of a bit‐interleaved coded modulation system. Moreover then, the moment generating functions of the legacy Gaussian and Laplacian metrics (LMs) for soft‐decision decoding of an employed error‐correcting code are derived for computing the upper bound on the BER and the corresponding coverage probability of the networks. Numerical results demonstrate that due to the impulsive nature of the inter‐cell interference for moderate‐to‐small cell loads, the networks using the LM for soft‐decision decoding significantly outperform those employing the legacy Gaussian metric in terms of the achievable cell radius and the amount of the average transmit power reduction.

With the rapid advances in the area of memory product, it has become more and more important to maintain its reliability while increasing the density and speed performance. Particularly, flash memory products have inherent difficulties in lengthening the limited lifetime due to the degradation of memory cell reliability caused by repeated read and/or write operations. To increase the benefits of high density flash memory, more advanced techniques such as multi-leveling the cell and signal processing has been adopted to the flash memory products. In this paper, arising challenges that leading engineers in semiconductor memory industries have confronted will be shared to further develop cutting-edge flash memory products.

In this paper, we analyze the performance of soft decision decoded, synchronous, fast frequency-hopping spread-spectrum multiple-access networks using M-ary frequency shift keying in Rayleigh fading channels under the assumption that the number of frequency hopping slots is sufficiently large. The joint probability density function (pdf) of the absolute values of the correlator outputs is derived to compute the channel capacity and evaluate the soft decision decoding performance of the 3GPP Turbo and convolutional codes. Results indicate that soft decision decoding based on the derived pdf drastically outperforms traditional decoders based on the Gaussian approximation of the effect of the multiple access interference (MAI). The sensitivity of the derived soft decision decoder to estimation errors in system parameters and the required computational complexities of the derived soft decision decoding metrics are also investigated.

In this paper, a distribution matching technique is proposed to process the extrinsic information produced by practical multiple-antenna detectors with iteratively demodulated, bit-interleaved coded modulation (BICM-ID). It is shown that significant gains may be achieved by appropriately processing the extrinsic information generated by practical multiple-antenna detectors before feeding it to the channel decoder. The validity of the proposed matching technique is shown via simulation results applied to Turbo-coded BICM-ID systems using (QRD)-M and list sphere detectors.

The probability density function (PDF) of the intercell interference for downlink cellular orthogonal frequency division multiple access networks under log-normal shadowing and multipath Rayleigh fading is derived. The derived PDF is observed to highly deviate from the Gaussian distribution, especially at moderate to small network loads. Based on the derived inter-cell interference statistics, the decoder performance can be significantly improved compared to the case when the traditional decoder optimized for the AWGN channel is employed. A simple suboptimum decoding algorithm that closely approximates the derived optimum decoder performance is also proposed.

An efficient synchronization scheme based on a repetitive preamble structure for orthogonal frequency division multiplexing systems was proposed by Schmidl and Cox. However, standard autocorrelation based estimation algorithms result in a plateau in the timing metric due to the cyclic prefix (CP), resulting in a region of uncertainty. Several modifications, either to the preamble structure itself or the estimation algorithm, have been proposed to remedy this problem. In this paper, we present a maximum-likelihood (ML) symbol timing estimation algorithm taking into account the presence of the CP. The performance of its practical modification is evaluated via computer simulations.