Information, energy and frequency efficiency

Generally the result of work of a transmission systems is defined by an quantity and quality of the transmitted information. The quantity is estimated by an information transmitting rate through a channel R _ch (bit per second), and quality – by the values of an error. According to Shannon theorems, the error with a corresponding choice of a transmission method (i.e. modulation/coding) can be made arbitrarily small (see explicitly the materials of the Module 2). At the same time, the transmission rate cannot be above some informational resource named a channel capacity C _ch. A. Zuko has suggested to consider as one of indicators of a system efficiency the value of mean rate R _ch at which the given fidelity of an information transferring is ensured. Thus the information system efficiency as degree of use of a channel capacity of the channel is defined by relative value . In real conditions the indicator h always is less than unit. The more close h to unit, the more absolutely transmitting information system. Reaching necessary for a transmission rate and fidelity is accompanied by certain expendituresof other major resources: signal power P _s and a channel frequency band F _ch. Such approach has allowed to introduce the indicators: power and frequency efficiency , uses of the mentioned resources characterizing degree. Here P _s /N ₀ – the ratio of a signal power to a power spectral density of noise on a receiver input). Thus, efficiency indicators by A. Zuko look like:

Information efficiency of systemwhich define the degree of channel capacity using

; (12.1)

Energy efficiency

; (12.2)

frequency efficiency

. (12.3)