Closed-loop transmit diversity schemes for five and six transmit antennas
Closed-loop, rate-one, channel orthogonalized space-time block codes (CO-STBCs) for three and four transmit antennas using a single (real) phase feedback term have been proposed [1]. These codes achieve full diversity and result in maximum likelihood (ML) decoding with only linear processing at the receiver similar to OSTBCs. In this paper, we propose a closed-loop STBC for five and six transmit antennas with rate 3/4, where the one parameter feedback angle can be evaluated in closed form. These codes achieve full diversity and are delay optimal. Simulation results comparing the error-rate performance of the CO-STBC with open-loop OSTBC as well as some quasiorthogonal space-time block codes are also provided. While the 1- to 5-dB gain accrued by the closed-loop scheme (over the open-loop methods) is not surprising, the novel contribution of this work is in the approach taken to derive the feedback parameter as a single phase term, which is purely a function of the channel gains. © 2005 IEEE.
Pre-processed space-time trellis codes with one-bit feedback
Open-loop (no feedback) pre-processing methods for improving the error-rate performance of space-time trellis codes in additive white Gaussian noise (AWGN) and Ricean channels which nearly preserve the performance in Rayleigh channels are proposed in [1]. The rotation based pre-processing preserves the Rayleigh channel performance, whereas there is a small degradation in performance in the power division based pre-processing. This degradation depends on the trellis complexity, and is more pronounced for the lower state trellis codes. In this letter, we propose a one-bit feedback method, that improves the performance of the power division method in Rayleigh channels. Simulation results for a 2 × 1 system show that this improvement is significant for the higher state trellis codes. The one-bit feedback is used to determine which of the two channels has a higher gain, and the higher power is assigned to the corresponding transmitter. © 2005 IEEE.
Performance analysis of antenna selection algorithms in spatial modulation systems with imperfect CSIR
Two antenna selection algorithms, namely the Euclidean Distance optimized Antenna Selection (EDAS) and Capacity Optimized Antenna Selection (COAS) are studied in the context of Spatial Modulation (SM) systems operating with the aid of imperfect Channel State Information at the Receiver (CSIR). The Symbol Error Rate (SER) performance of these schemes is compared to that of the conventional MIMO (CMIMO) system employing transmit antenna selection. It was observed that the SM system employing antenna selection attains significant Signal-to-Noise Ratio (SNR) gains compared to the C-MIMO system employing antenna selection, especially in the low to moderate SNR regime. Furthermore, we propose a lowcomplexity iterative data-detection/channel-estimation algorithm for the SM system operating with imperfect CSIR that offers an almost identical SER performance as that of the SM system operating with perfect CSIR. © VDE VERLAG GMBH.
Orthogonal decode and forward relaying with improved spectral efficiency
Cooperative relay communications can significantly improve the reliability of data transmission over wireless fading channels by implementing spatial diversity in a distributed fashion. Orthogonal decode and forward (ODF) relaying achieves maximum diversity provided by the source-destination and relaydestination channels, but suffers from low spectral efficiency. We propose a novel ODF protocol having higher spectral efficiency without sacrificing the diversity gain. We analyze the symbol error probability of the proposed protocol and also present simulation results. © 2009 IEEE.