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In order to mitigate the deleterious effects of multipath fading in satellite wireless channels, forward error correction (FEC) techniques had been used for past several decades. Reed-Solomon (RS) coding is one of the preferred FECs for current satellite systems that experience deep fading. For satellite channels, often a direct path also exists al...
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Context 1
... block diagram of a digital communication system employing RS coding is given below in Fig. 1. The information source fed symbols to the RS encoder and the encoded outputs are modulated before they can be sent over a noisy fading channel. This resulting noisy received signal is first demodulated and then fed to the RS decoder to get the final decoded output. ...
Context 2
... communication system model described in Fig. 1 has been implemented over Matlab platform to validate the BER expression of a RS coded digital BPSK signal derived in Section IV. Fig. 2 elaborates the detailed simulation process. First, a random binary data stream is generated and encoded via RS coding technique. As the related function rsenc() accepts a GF array, the function gf() ...
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Citations
... By varying coding rate, we can reduce the requirement of SNR for a particular BER value [7,8]. This property can be used to mitigate the effect of atmospheric turbulence. ...
... In this technique, periodically each day noise statistics are collected by switching off the FSO transmitter for some time. After that we sample the received signal continuously and calculate the first and second moment of received signal [8]. ...
... Important constraint which should be satisfied in order to use ACM technique is (8) where are coherence time (typically 1-100 ms), path delay due to link length, transmitter processing time, receiver processing time and data rate delay, respectively. The latter delay depends on the data rate of RF feedback link. ...
One of the major factors which degrades the Free Space Optics (FSO) link performance is the atmospheric turbulence. Turbulence manifests in increased Bit Error Rate (BER) leading to degradation in the link performance. Adaptive Coding and Modulation (ACM) technique is used to mitigate this effect. This technique is an adaptive transmission scheme wherein transmission parameters such as modulation scheme, code rate, etc., are adjusted based on Channel State Information (CSI). In this paper, we have considered lognormal channel model in low turbulence conditions. Three adaptive transmission schemes viz., variable data rate, variable modulation schemes and variable coding rate are considered. The entire work has been carried out in MATLAB. We see improvement in FSO link performance in terms of average transmitted data rate when variable data rate adaptation scheme is used. Improvement in spectral efficiency is observed when the other two adaptation schemes are used. Design of adaptive transmitter for all the three schemes is presented and data rate of RF feedback channel is determined.
... Further, p i is given by, p i = n i P i in (1 − P in ) n−i , i.e. the probability of an aggregate of i failures for a sequence of n independent Bernoulli trials. The argument leads to the following expression of P out [13] (13) Finally, the bit error probability at the output of RS decoder, P e,c , may be found from the symbol error rate, P out , as ...
... Further, p i is given by, p i = n i P i in (1 − P in ) n−i , i.e. the probability of an aggregate of i failures for a sequence of n independent Bernoulli trials. The argument leads to the following expression of P out [13] (13) Finally, the bit error probability at the output of RS decoder, P e,c , may be found from the symbol error rate, P out , as ...
Power line communication (PLC) systems are being standardized over the globe and some of these standards recommended frequency shift keying (FSK) as their modulation choice. Broadband transmission over a PLC channel is mainly affected by the ever-present background noise and the occasional high-amplitude impulses. It has been recently found that the background noise in PLC can be suitably modelled with Nakagami-m distribution while a standard model for characterizing impulses is to assume Gaussian distributed amplitude and Poisson distributed arrivals. Considering such a model, at first, simple analytical bit error rate (BER) expressions of uncoded binary FSK (BFSK) signals are derived in the paper. Next, a unified analytical framework is presented for evaluating BER when a Reed Solomon (RS) code is used to mitigate the noise effects. The results reveal that when the signal to background noise ratio (SNR) is low, the noise parameter m and the demodulation scheme affects the performance of the coded system. On the contrary, at higher SNR, impulsive noise dominates over background noise, and these effects vanish as the BER curve becomes flat. Numerical evaluations dictated that by allowing a lower code rate (0.7) this error floor may be reduced significantly (up to 10-15). The code gain of the system was found to be an inverse function of the code rate and codeword length.
