Proc. of Allerton Conference on Signals and Systems, Monticello, IL, Oct. 1-3, 2003.
Spatial multiplexing is a simple transmission technique for multiple-input multiple-output (MIMO) wireless communication links in which data is multiplexed across multiple transmit antennas. Spatial multiplexing with low complexity linear receivers, however, suffers due to a lack of diversity advantage in Rayleigh fading channels. This paper proposes multi-mode antenna selection which uses a low-rate feedback channel to improve the error rate performance of spatial multiplexing systems with linear receivers. In the proposed technique, for a fixed total data rate, both the number of substreams and the antenna subset used for transmission are dynamically adjusted to the channel using a limited number of feedback bits sent from the receiver. Using multi-mode selection - effectively allowing any number of substreams to be dynamically selected - provides additional array gain over standard transmit diversity. Various criteria for selecting the number of substreams and the optimal antenna subset of transmit antennas are derived. Relationships are made between the selection criteria and the eigenmodes of the channel. Monte Carlo simulations demonstrate significant performance improvements in i.i.d., flat-fading Rayleigh matrix channels with minimal feedback.
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