Combined Space Time Block Coding Research Articles

Performance Analysis of Combined Space Time Block Coding with Generalized Selection Combining in Underlay Cognitive Radio

In this paper, we demonstrate the performance analysis of an underlay MIMO cognitive radios employing space time block coding at secondary’s user transmitter (SU-Tx) and generalized selection combining at secondary’s user receiver. The transmit power strategy enforces the SU-Tx to adapt its power to be transmitted so as to protect primary user’s receiver from harmful interference in order to satisfy primary user outage constraint. We derive closed form expressions for average post processing signal to noise ratio and ergodic capacity. Moreover, approximate expression for average bit error rate is also obtained. Based on the achieved results, we show that the average post processing SNR, Ergodic Capacity and average BER improve as number of best branches to be combined increases. Finally analytical results are affirmed through Monte Carlo simulations.

Combined beamforming with space-time-frequency coding for MIMO–OFDM systems

Multiple antennas can be used in wireless systems to achieve good quality of service and high data rate communication. Recently, efficient space-time-frequency (STF) codes have been developed to improve the diversity gain. This paper aims at performance analysis of multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO–OFDM) system using STF Coding and random beamforming. The proposed approach which combines beamforming with STF code offers improved performance over STF in term of bit error rates (BER). It is also observed that the proposed scheme gives better performance as compared to the combined space-time block code (STBC) with beamforming. Computational complexity of the proposed scheme is also calculated.

Performance Comparison of Detection Methods for Combined STBC and SM Systems

This paper considers detection schemes for the combined space-time block coding and spatial multiplexing (STBC-SM) transmission systems. We propose a symbol detection scheme which allows to extend the limit on the number of transmit antennas imposed by the previous group detection scheme. The proposed scheme allows to double multiplexing gain as well as provides better bit error rate (BER) performance over the group detection scheme. It is shown that the proposed QR-SIC (combined QR-decomposition and successive interference cancellation) symbol detector provides good trade-off between the BER and computational complexity performance and, thus, is the most suitable detector for the combined STBC-SM system.

Combined space–time block coding and eigen-space tracking in MIMO systems

A combined space–time block coding (STBC) and eigen-space tracking (EST) scheme in multiple-input-multiple-output systems is proposed. It is proved that the STBC-EST is capable of shifting hardware complexity from the receiver to the transmitter without any bit error rate (BER) performance loss. A computation efficient EST algorithm is also proposed, which makes the STBC-EST affordable. Simulation results show that the STBC-EST with a modest feedback requirement results in a negligible BER performance loss compared with a dual system configuration.

Bezout space-time precoders and equalizers for MIMO channels

The transmitter/receiver diversities in p-input-q-output multiple-input multiple-output (MIMO) channels will play a key role in future high-rate wireless communication. The major challenge in MIMO signal recovery is the mitigation of the inevitable intersymbol interference (ISI) and interchannel interference (ICI) in multipath MIMO channels. The Bezout system theory provides a simple solution for ISI/ICI cancellation and, thus, can serve as a powerful mathematical foundation for MIMO systems. If p<q and the MIMO system H(D) is right coprime, the system is perfectly recoverable via a Bezout equalizer. If p>q and the MIMO system H(D) is left coprime, the system is perfectly recoverable via a Bezout precoder, assuming the channel information is available at the transmitter. For a robust channel design, a quantitative analysis of signal-to-noise ratio (SNR) of the optimal Bezout equalizer/precoder can be derived from the Bezout null space. Compared with the Alamouti(see IEEE J. Select. Areas Commun., vol.16, p.1451-58, Oct. 1998) space-time coding, the Bezout precoder is shown to be more appealing in slowly time-varying channels, where the feedback of the channel information induces minor overhead. The Bezout system can work well jointly with the space-time block coding (STBC). The STBC can be adopted to artificially construct a larger q'/spl times/p' (q'>p') virtual transfer function without the channel information. A necessary and sufficient condition is provided for perfect recoverability (PR) for the STBC-induced virtual MIMO systems. Based on the virtual transfer function, both channel-independent and channel-dependent precoding strategies are feasible. Via a singular value decomposition (SVD) analysis, the Bezout precoder can be shown to outperform the orthogonal frequency division multiplexing (OFDM) precoder in bit-error-rate (BER), transmission rate, and receiver implementation. The interplay of the two design parameters (N and /spl rho/) is analyzed to provide a simple guideline for an optimal configuration. The combined STBC and Bezout equalization techniques offer a broader spectrum of transceiver system configuration to achieve optimal design tradeoff among BER, transmission rate, and implementation complexity.