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Transmit Power Adaptation for Multiuser OFDM Systems
Cited 899 time in
Web of Science
Cited 1232 time in Scopus
- Authors
- Issue Date
- 2003-02
- Citation
- IEEE J. Select. Areas Commun., vol. 21, pp. 171-178, Feb. 2003
- Keywords
- Channel capacity ; downlink ; multicarrier ; orthogonal frequency division multiplexing (OFDM) ; power control ; water-filling
- Abstract
- In this paper,we develop a transmit power adaptation
method that maximizes the total data rate of multiuser orthogonal
frequency division multiplexing (OFDM) systems in a downlink
transmission. We generally formulate the data rate maximization
problem by allowing that a subcarrier could be shared by multiple
users. The transmit power adaptation scheme is derived by solving
the maximization problem via two steps: subcarrier assignment for
users and power allocation for subcarriers.We have found that the
data rate of a multiuser OFDM system is maximized when each
subcarrier is assigned to only one user with the best channel gain
for that subcarrier and the transmit power is distributed over the
subcarriers by the water-filling policy. In order to reduce the computational
complexity in calculating water-filling level in the proposed
transmit power adaptation method, we also propose a simple
method where users with the best channel gain for each subcarrier
are selected and then the transmit power is equally distributed
among the subcarriers. Results show that the total data rate for
the proposed transmit power adaptation methods significantly increases
with the number of users owing to the multiuser diversity
effects and is greater than that for the conventional frequencydivision
multiple access (FDMA)-like transmit power adaptation
schemes. Furthermore, we have found that the total data rate of
the multiuser OFDM system with the proposed transmit power
adaptation methods becomes even higher than the capacity of the
AWGN channel when the number of users is large enough.
- ISSN
- 0733-8716
- Language
- English
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