In this paper, we explore the spatial modulation (SM) orthogonal frequency division multiplexing (SM-OFDM) transmission to achieve good performance in Long Term Evolution (LTE) based systems For assessment purposes, the performance results of SM-OFDM systems are compared with the popular Alamouti-coded OFDM systems and vertical Bell Labs layered space-time (V-BLAST) OFDM systems Simulation results show that SM-OFDM systems achieve better performance than other systems at low spectral efficiencies However, at high spectral efficiencies, the performance of SM depends on a trade-off between the spatial constellation size and signal constellation size Furthermore, the results also show that SM provides a flexible transceiver configuration, especially for an unbalanced multiple-input multiple-output (MIMO) channel

Initial performance evaluation of spatial modulation OFDM in LTE-based systems

In this paper, we consider multiple-input multiple-output MIMO multi-tone code division multiple access MT-CDMA uplink transmission over multipath fading channels. The zero-forcing vertical Bell Laboratories layered space-time architecture ZF V-BLAST algorithm and maximum ratio combining scheme are applied at the receiver. The average bit error rate BER expression is derived provided that the number of receive antennas is not less than that of transmit antennas. The BER expression is verified by simulations. Numerical results show that the numbers of transmit and receive antennas have significant effects on the BER performance of the considered system. Spatial and path diversity show different capabilities to improve the BER performance. The MIMO MT-CDMA system based on the ZF V-BLAST algorithm is capable of achieving a better BER performance and a higher capacity than the conventional MT-CDMA system. Copyright © 2011 John Wiley & Sons, Ltd.

Performance analysis of uplink spatial multiplexing MIMO MT-CDMA over multipath fading channels

Based on orthogonal designs, space-time (ST) block codes that enable full diversity as well as a simple maximum likelihood (ML) decoding algorithm at the decoder can be constructed for more than two transmit antennas. For real constellations (such as PAM), ST block codes with transmission rate 1 can be designed from the real Hurwitz-Radon families for any number of transmit antennas. However, for complex constellations (such as M-PSK or M-QAM), ST block codes for more than two transmit antennas can only be constructed with rates less than 1. Previous attempts have been concentrated on complex orthogonal designs that provide ST block codes with full diversity and high transmission rates. In this paper, we present two rate 2/3 complex ST block codes from orthogonal designs for five and six transmit antennas, respectively. Simulation results are provided to demonstrate the significant performance gains made by the proposed ST block codes.

High-rate Complex Orthogonal Space-time Block Codes for 5 and 6 Transmit Antennas

Based on the one-dimensional dirty paper coding (DPC) system, a low complexity algorithm is proposed to calculate log likelihood ratios (LLRs) for multi-level quadrature amplitude modulation (M ? QAM). The M ? QAM constellation is split into the in-phase and quadrature $${\sqrt{M}-PAM}$$ signal of mutual independence, and the LLR value of each bit is calculated on the expanded $${\sqrt{M}-PAM}$$ constellation. For both the complete interference pre-subtraction and partial interference pre-subtraction schemes, accurate LLR values can be obtained using the proposed simplified algorithm. The proposed algorithm is applied to the one-dimensional DPC system using convolutional code and low density parity check code respectively. Simulation results indicate that the bit error rate performance is almost not lost with the simplified algorithm while the computational complexity is reduced significantly.

Wei Yang

Papers

High-rate Complex Orthogonal Space-time Block Codes for 5 and 6 Transmit Antennas

A Soft Demodulation Algorithm with Low Complexity for One-dimensional DPC System