Ibrahim C. Abou-Faycal

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We consider transmission over a discrete-time Rayleigh fading channel, in which successive symbols face independent fading, and where neither the transmitter nor the receiver has channel state information. Subject to an average power constraint, we study the capacity-achieving distribution of this channel and prove it to be discrete with a finite number of(More)
Pilot symbol assisted modulation (PSAM) is a standard approach for transceiver design for time-varying channels, with channel estimates obtained from pilot symbols being employed for coherent demodulation of the data symbols. In this paper, we show that PSAM schemes can be improved by adapting the coded modulation strategy at the sender to the quality of(More)
The lazy Viterbi decoder is a maximum-likelihood decoder for block and stream convolutional codes. For many codes of practical interest, under reasonable noise conditions, the lazy decoder is much faster than the original Viterbi decoder. For a code of constraint length , the lazy algorithm is about 50% faster than an optimized implementation of the Viterbi(More)
We derive, for a binary antipodal input signal, the optimal uncoded regenerator function when the channels at the ingress and at the egress of the regenerator are degraded by AWGN. We show that the optimal function is a Lambert W function parametrized on the energies of the noises and the input. For comparison, we derive the performance of systems in which(More)
We consider adaptive modulation and coding for channels with pilot symbol assisted modulation. Unlike most adaptive transmission schemes, we do not have any channel side information at the sender. The sender adapts not to the state of the physical channel traversed by its transmitted signal, but to the quality of the measurement a orded by pilot symbols at(More)
This paper studies classes of generic deterministic, discrete time, memoryless, and “nonlinear” additive white Gaussian noise (AWGN) channels. Subject to multiple types of constraints such as the even-moment and compact-support constraints or a mixture, the optimal input is proved to be discrete with finite number of mass points in the vast(More)
Pilot symbol assisted modulation (PSAM) is a standard approach for transceiver design for time-varying channels, with channel estimates obtained from pilot symbols being employed for coherent demodulation of the data symbols. In this paper, we show that PSAM schemes can be improved by adapting the coded modulation strategy at the sender to the quality of(More)
In communication over time-varying Rayleigh fading channels, adaptive coded modulation for Pilot Symbol Assisted Modulation (PSAM) without feedback has been shown to yield significant benefits in terms of achievable rates [1]. This technique adapts transmission rate at the sender to the quality of the channel estimate at the receiver but keeps the mean(More)
We analyze the error probability of peaky signaling on bandlimited multipath fading channels, the signaling strategy that achieves the capacity of such channels in the limit of infinite bandwidth under an average power constraint. We first derive an upper bound for general fading, then specialize to the case of Rayleigh fading, where we obtain upper and(More)
In this work, we consider a discrete-time memoryless communication channel where the input is subjected to an independent additive Cauchy noise. We find the input constraint under which a Cauchy input is capacity achieving. The constraint is logarithmic and depends on a scalar parameter k which we interpret as a power measure. We draw a parallelism between(More)