Optimal Rate and Power Allocation for OFDM in the Presence of Channel Uncertainty


C. Liu, D. Bielefeld, R. Mathar,


        Adaptive modulation of subcarriers of an orthogonal frequency
division multiplexing (OFDM) system has been shown to improve the
system performance significantly. Prerequisite to use it is the
availability of channel state information at the transmitter. Due to
noisy channel estimation at the receiver perfect channel state
information cannot be achieved in practical systems. The reliability
of a channel estimate can be provided by soft channel estimation
algorithms and then depends on the frame length. In this paper, we
analytically investigate the influence of the estimation reliability
in terms of the frame length on the performance of adaptive
modulation in OFDM for the margin- and rate-adaptive cases.
Numerical results verify that this influence might not be neglected
for the frame lengths employed in practical systems.

BibTEX Reference Entry 

	author = {Chunhui Liu and Daniel Bielefeld and Rudolf Mathar},
	title = "Optimal Rate and Power Allocation for {OFDM} in the Presence of Channel Uncertainty",
	booktitle = "{IEEE} PIMRC",
	address = {Cannes, France},
	month = Sep,
	year = 2008,


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