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Register a new userAsynchronous Communication over a Fading Channel and Additive Noise
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R M Sundaram
Publication date
2015
fields
Informatics Engineering
and research's language is
English
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In cite{Chandar2008}, Chandar et al studied a problem of sequential frame synchronization for a frame transmitted randomly and uniformly among $A$ slots. For a discrete memory-less channel (DMC), they showed that the frame length $N$ must scale as $e^{alpha(Q)N}>A$ for the frame detection error to go to zero asymptotically with $A$. $alpha(Q)$ is the synchronization threshold and $Q$ is channel transition probability. We study the sequential frame synchronisation problem for a fading channel and additive noise and seek to characterise the effect of fading. For a discrete ON-OFF fading channel (with ON probability $p$) and additive noise (with channel transition probabilities $Q_n$), we characterise the synchronisation threshold of the composite channel $alpha(Q)$ and show that $alpha(Q)leq p,alpha(Q_n)$. We then characterize the synchronization threshold for Rayleigh fading and AWGN channel as a function of channel parameters. The asynchronous framework permits a trade-off between sync frame length, $N$, and channel, $Q$, to support asynchronism. This allows us to characterize the synchronization threshold with sync frame energy instead of sync frame length.
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We study a problem of sequential frame synchronization for a frame transmitted uniformly in $A$ slots. For a discrete memoryless channel (DMC), Venkat Chandar et al showed that the frame length $N$ must scale with $A$ as $e^{N alpha(Q)} > A$ for the frame synchronization error to go to zero (asymptotically with $A$). Here, $Q$ denotes the transition probabilities of the DMC and $alpha(Q)$, defined as the synchronization threshold, characterizes the scaling needed of $N$ for asymptotic error free frame synchronization. We show that the asynchronous communication framework permits a natural tradeoff between the sync frame length $N$ and the channel (usually parameterised by the input). For an AWGN channel, we study this tradeoff between the sync frame length $N$ and the input symbol power $P$ and characterise the scaling needed of the sync frame energy $E = N P$ for optimal frame synchronisation.
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