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2004
Conference Paper
Titel
On the OFDM multiuser downlink capacity
Abstract
In this paper we characterize the OFDM multiuser downlink capacity region under a sum power constraint and perfect channel knowledge at the base station. This serves as a fundamental limit for all transmission strategies. We derive the corresponding power control strategy and provide necessary and suficient conditions for both the single user and Frequency Division Multiple Access (FDMA) optimality range. It is shown that, unlike the sum capacity case, FDMA is not always optimal and power control is complex. On the other hand, the solution can be simplied in the single user and FDMA region by applying a modified weighted waterfilling over the selected subcarriers.