مرکز منطقه ای اطلاع رساني علوم و فناوري - High-speed binary data transmission over the additive band-limited Gaussian channel

Abstract :

The transmission of the linear sum of $m$ biphase modulated signals in a time interval $T$ is considered for an additive Gaussian white noise channel of bandwidth $W$ . Previous analyses consider the case where $m \\leq n \\equiv 2WT$ . In this paper, the probability of error is derived for $m > n$ , a situation which arises when the channel bandwidth is insufficient to support the data rate. Two distinct problems are considered. In the first, termed uncoded transmission, all $m$ signals are independently biphase modulated. It is shown, for this case, that if the channel signal-to-noise ratio increases linearly with $n$ , the error probability can be made to go to zero approximately exponentially in $n$ for any value of $m/n$ . In the second problem, termed ceded transmission, only $k < m$ of the signals are independently modulated. (The remaining $(m - k)$ signals carry redundant information.) By using a suboptimum receiver, it is shown that for a fixed channel signal-to-noise ratio the error probability goes to $0$ exponentially in $n$ if $k/n$ is less than some number $C^{\\ast }$ . For high signal-to-noise ratio, $C^{\\ast }$ is greater than $1$ , a situation which could not occur if $m \\leq n$ .