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Multiuser scheduling using equal power in allocated subcarriers for OFDM uplink

: Giovanidis, A.; Haustein, T.; Hadisusanto, Y; Sezgin, A.; Kim, D.


Institute of Electrical and Electronics Engineers -IEEE-:
Fortieth Asilomar Conference on Signals, Systems and Computers 2006 : Pacific Grove, CA, 29 October - 1 November 2006
Piscataway, NJ: IEEE Operations Center, 2006
ISBN: 1-424-40784-2
ISBN: 1-4244-0785-0
Asilomar Conference on Signals, Systems and Computers <40, 2006, Pacific Grove/Calif.>
Fraunhofer HHI ()
channel allocation; channel capacity; multiuser channel; ofdm modulation; optimisation; scheduling

In this paper the problem of optimal subcarrier and power allocation for sum rate maximization in the uplink of an OFDMA system is considered, under the assumption that each user allocates equal transmit power to an assigned subset of subcarriers. Such On-Off power allocation requires very limited feedback from the base station to the users. Furthermore the intertwined power/subcarrier allocation problem simplifies considerably. Solving a relaxed Lagrange optimization problem we derive necessary optimality conditions for both the single- and multiuser channel. These suggest practical allocation rules leading to a low complexity O (KN log N) logarithm free algorithmic solution. Simulation results indicate that the proposed algorithm outperforms already suggested equal power algorithms providing sum rates with negligible distance from the capacity achieving multiuser waterfilling solution.