نتایج جستجو برای: fading
تعداد نتایج: 19732 فیلتر نتایج به سال:
Packet level network protocol simulators use simple channel models for computational efficiency. A typical method for doing this is to compute a packet error probability assuming a certain fading distribution without taking into account time-correlation. This paper introduces work that has been done to model the effect of small-scale fading (Rayleigh and Ricean) within the ns network simulatol:...
The packet error rate (PER) is a metric of choice to compute the practical performance of communication systems experiencing block fading, e.g., fading processes whose coherence time is relatively slow when compared to the symbol transmission rate. For these types of channels, we derive a closed-form asymptotic expression which approximates the value of the PER for high signal-to-noise ratio (S...
In this paper we discuss the proper normalization of a fading channel model. Physically, radio channels correspond to passive circuits and follow the energy conservation law. The ratio of the received energy to the transmitted energy is the energy gain of the channel. The representative energy gain is defined as the average energy gain for a signal that is uniformly distributed in time, frequen...
Adaptive transmission techniques such as adaptive modulation and transmitter antenna diversity have been proposed for mobile wireless systems to satisfy high data-rate service requirements. In rapidly time variant channels, these methods need the knowledge of future fading conditions and therefore require accurate long range fading prediction. We investigate three combined adaptive modulation...
In this work, we observe the behavior of block space-time code in wireless channel dynamics. The block space-time code is optimally constructed in slow fading. The block code in quasi-static fading channels provides affordable complexity in design and construction. Our results show that the performance of the block space-time code may not be as good as conventionally convolutional coding with s...
We study the high-SNR capacity of generic MIMO Rayleigh block-fading channels in the noncoherent setting where neither transmitter nor receiver has a priori channel state information but both are aware of the channel statistics. In contrast to the well-established constant block-fading model, we allow the fading to vary within each block with a temporal correlation that is “generic” (in the sen...
Original scientific paper The wireless telecommunication system consisting of selection combining (SC) receiver which works in Gamma shadowed Weibull multiple-faded channel is discussed in this work. The received signal suffers Weibull small scale fading which leads in variation of the signal envelope and Gamma large scale fading which results in variation of the SC receiver output signal envel...
Accurate performance evaluation of direct-sequence pseudonoise code acquisition on Rayleigh fading channels is investigated in this paper. For fading channels the homogeneous Markov chain model, used to characterize the acquisition process over additive white Gaussian noise channels, is no longer valid due to the correlations between cell detections incurred by fading. Hence, the traditional di...
This paper presents a worst-case pairwise codeword error probability analysis, under arbitrary block fading, for wireless communication systems with multiple transmit and receive antennas. Our results generalize the Rayleigh-fading space-time code design criteria (full rank and maximum determinant) to arbitrary fading. Keywords— Space-time codes, multiple transmit antennas, product distance.
We present results on the high signal-to-noise ratio (SNR) asymptotic capacity of peak-power limited single-antenna discrete-time stationary complex-Gaussian fading channels with memory, where the transmitter and receiver, while fully cognizant of the fading law, have no access to its realization. Complementing recent results of Lapidoth & Moser about the case where the fading process is regula...
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