d the channel capacity. Together with the above expressions for the received signal power and noise power, this leads to 4.3.1 High data rates: Fundamental the inequality constraints Shannon provided the basic theoretical tools needed to determine the maximum rate, also known as the (4.3.2) channel capacity, by which information can be trans- ferred over a given communication channel. Although relatively complicated in the general case, for the special case of communication over a channel, e.g. or, by defining the radio-link bandwidth utilization a radio link, only impaired by additative white Gauss- Y : R/BW, ian noise, the channel capacity C is given by the rela- tively simple expression (4.3.3) C = BW-1082(1+N) (4.3.1) This inequality can be reformulated to provide a lower bound on the required received energy per information where BW is the bandwidth available for the communi- bit, normalized to the noise power density, for a given cation, S denotes the received signal power, and bandwidth utilization Y Communications Engineering Desk Reference; ISBN: 9780123746481 Copyright © 2007, Erik Dahlman, Stefan Parkvall, Johan Skold and Per Beming. Published by Elsevier Ltd 2001. All rights reserved CHAPTER 4.3 High data rates in mobile communications increase of the received signal power. At the same (4.3.4) time, if sufficient received signal power can be made available, basically any data rate can, at least in theory, The rightmost expression, i.e. the minimum required be provided within a given limited bandwidth. Eb/No at the receiver as a function of the bandwidth In case of low-bandwidth utilization, i.e. as long as the utilization is illustrated in Figure 4.3-1. As can be seen, radio-link data rate is substantially lower than the for bandwidth utilizations significantly less than one, that available bandwidth, any further increase of the data is for information rates substantially smaller than the rate requires approximately the same relative increase utilized bandwidth, the minimum required Eb/No is in the re