Stochastic Method of Determining Substream Modulation Levels for MIMO Eigenbeam Space Division Multiplexing

Chang-Jun AHN
Hiroshi HARADA

IEICE TRANSACTIONS on Communications   Vol.E89-B    No.1    pp.142-149
Publication Date: 2006/01/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.1.142
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
mobile radio propagation,  adaptive modulation,  multipath environments,  ray tracing,  MIMO,  E-SDM,  

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Multiple-input multiple-output (MIMO) eigenbeam space division multiplexing that uses adaptive modulations for substreams is a promising technology for improving transmission capacity. A fundamental drawback of this approach is that the modulation levels determined from the carrier-to-noise ratio at each substream are sometimes overly optimistic so the use of these modulation levels results in transmission errors and diminished transmission performance. A novel method of determining substream modulation levels is proposed that alleviates this degradation. In the proposed method, the expected bit error rates for possible modulations of each substream are calculated from delay profiles. Simulation results indicate that transmission capacity is improved by 30% using the new method compared with the conventional method.