Precoded BICM design for MIMO transmit beamforming and associated low-complexity algebraic receivers

Abstract-In this paper, we design bit interleaved coded modulations including a partial algebraic precoder in order to transmit several spatial streams with full diversity over a transmit beamformed MIMO channel. The achievable diversity orders with the coded modulation are derived, and allow for efficiently choosing the system parameters for optimizing the performance. Additionnally, a very efficient low complexity soft output detector based on algebraic reduction is presented. With a low complexity at the receiver, the precoded BICM system allows achieving high performance at very high efficiencies, e.g., 12 bits per second per hertz. I. INTRODUCTION The new standards of wireless communications, e.g., 802.11n and 3GPP-LTE, include a variety of techniques for transmitting over mutliple antenna channels: Spatial-division multiplexing, space-time block coding, transmit beamforming, and so on. A trade-off between data rate, range, mobility and receiver complexity can be achieved by a relevant choice of the transmission technique. In this paper, we focus on low mobility users and transmit beamforming techniques. For low and average spectral efficiencies, the MIMO channel capacity can be maximized by transmitting on the best eigenvalue of the channel realization and can be further improved by applying water-filling techniques In section II, we present the channel model and notations. In section III, the equivalent channels as seen by the decoder input and including a partial precoder are described, while achievable bounds on the diversity for these channels are derived in section IV. These bounds are used to choose the optimal size of the partial algebraic precoder. In section V, w