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2006
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Optimality of FDMA in Gaussian Multiple-Access Channels with Non-zero SNR Margin and Gap

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Optimality of FDMA in Gaussian Multiple-Access Channels with Non-zero SNR Margin and Gap
— This paper investigates the effect of non-zero SNR margin and coding gap on the maximum sum rate and achievable rate region of the Gaussian Multiple-Access Channel (MAC). Frequency-division multiple-access (FDMA) is shown to be the only sum-rate-maximizing scheme for a scalar Gaussian MAC when the margin/gap is not zero. Furthermore, successive decoding is shown to be strictly sub-optimal from a sum rate perspective. With fixed probability-of-error, single-user codes with finite gap are sufficient to achieve the maximum sum rate. The achievable rate region of the scalar Gaussian MAC with non-zero margin/gap is also characterized. Unlike the capacity region of a scalar MAC, the optimal achievable rate region with non-zero margin/gap is not a pentagon. Finally it is shown that when there is non-zero margin/gap, the optimality of the FDMA scheme can be generalized to a Gaussian MAC with inter-symbol interference (ISI).
Sumanth Jagannathan, John M. Cioffi
Added 11 Jun 2010
Updated 11 Jun 2010
Type Conference
Year 2006
Where GLOBECOM
Authors Sumanth Jagannathan, John M. Cioffi
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