Hanly and Tse (see Proc. 33rd Annual Allerton Conference onCommunication, Control, and Computing, Monticello, IL, 1995), and alsoCheng (see Proc. of IEEE Information Theory Workshop (ITW), p.36, Haifa,Israel, 1996) have generalized the results on the Gaussian multipleaccess channel to the case where flat fading occurs which can be trackedby both the receiver and transmitter. They distinguish two cases whichthey term Shannon and delay-limited capacity of that channel. With theShannon capacity they refer to the case where the capacity regionexpected over the fading statistics is maximized for the constrainedaveraged sum power of all users. The practically more importantso-called delay-limited capacity results from minimizing the sum energyof all users for fixed rates. In the article we focus on the secondcase. Instead of assuming a single receiver only we study the case ofmultiple receivers since in implemented systems diversity reception isused often. This can be caused e.g. by multiple receive antennas(receiver antenna diversity) for signal separation, or by multiplecell-site processing in cellular systems. Surprisingly, we show thatsome results which are valid for the case without diversity do notgeneralize to the diversity model
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