Power Allocation for Quasi-Orthogonal Space-Time Block Codes with 1 or 2 Bits Feedback

Abstract

In this paper, a closed-loop wireless communication system employing Quasi-Orthogonal Space-Time Block Codes (QOSTBCs) is presented, where the total available power can be suitably allocated to the four transmit antennas, considering a very low-complexity decoding scheme at the receiver side. After deriving a particular optimization problem concerning the optimal choice of the power weights, we prove that the best strategy in terms of error probability is to switch-off three out of the four transmit antennas under the requirement of symbolby-symbol maximum-likelihood decoding (MLD). Our proposed scheme requires a very low-data rate dedicated feedback link, since just one or two bits per block are sufficient for outperforming other existing closed-loop systems. The technique applies to all the well-known QOSTBCs with arbitrary number of receive antennas, while some special cases are taken indicatively for illustration purposes.

Enhanced closed‐loop EOSTBC schemes for multiple transmit antennas

“…For the slow-fading channels, a single feedback bit scheme is proposed by employing the differential coding to exploit the smooth variation of the channel coefficients [10]. Similar research work has also been found on the quasi-orthogonal STBC [11][12][13]. Additionally, many researches have come into being focussing on the closedloop design by combining STBC with pre-coding [14,15], beamforming [16] or transmit antenna selection [17,18], and so on.…”

Performance analysis comparison of transmit antenna selection with maximal ratio combining and orthogonal space time block codes in equicorrelated Rayleigh fading multiple input multiple output channels

“…Rayleigh fading channels. It has been further shown in [14] that TAS/MRC outperforms all quasi-OSTBC schemes for i.i.d. Rayleigh fading channel.…”

“…Henceforth, we will use the notation z = 1/P t g(1 − r √ ) . The integral in (14) can be evaluated by linearising the product of incomplete gamma functions using the method given in [16]. Using the same method the linearised product is calculated in Appendix 1.…”

One Bit Feedback Based Diagonal Precoding for Non-Orthogonal Space-Time Block Codes

“…Quantized feedback is a promising method to achieve notable performance gain in MIMO system by transmitting a few bits feedback about CSI from receiver to transmitter; so turns out to be practically suitable. In literature, it is shown that error performance of OSTBC and Quasi-OSTBC (QOSTBC) [10] can be improved by using quantized feedback of CSI at the transmitter [9], [11]- [14]. These works focused on design of diagonal weighting precoder for OSTBC and QOSTBC.…”