Orthogonal Space-time Block Code Transmission Research Articles

MIMO AF RSs Based OSTBCs for LTE-A Downlink Physical Layer Network

The link performance between base station (BS) and user equipment (UE) in long term evolution-advanced (LTE-A) system is already quite close to the Shannon limits and from a pure link-budget perspective, the highest data rates supported by LTE-A require a relatively high signal-to-noise ratio. In later releases of LTE-A, various tools such as relaying, enhancing the support for low-power BSs and improving the link budget are included. This paper studies the relay stations (RSs) for LTE-A downlink physical layer. Multi-input multi-output amplify-and-forward RS is used to enhance the received signal of UEs at cell edge. This paper proposes RSs with orthogonal space–time block codes (OSTBC) transmission for LTE-A system. The received signals for different UEs scenarios are mathematically derived and analyzed. The symbol error rate performance of proposed LTE-A system is illustrated for the scenarios of UEs. Results show that the proposed LTE-A system based RSs with OSTBC transmission improve link performance and achieve higher diversity gains.

OSTBC Transmission in Large MIMO Systems

We address the problem of orthogonal space-time block code (OSTBC) transmission in a large multiple-input multiple-output (MIMO) system in Rayleigh fading environment. Because there are hundreds of antennas at the transmitter, a very large dimension OSTBC is required in the case of massive MIMO system. Full rate OSTBC is available only for two transmit antenna-based system with complex symbols. Recently, an implementation of OSTBC for 32 transmit and 32 receive antennas is presented for real symbols. In this letter, we present a scheme of OSTBC transmission for practical large MIMO systems by embedding the OSTBCs of small dimensions with good rate. At the receiving end, the decoding of the OSTBCs is performed by utilizing the concept of null space. It is shown by simulation and analysis that the code rate can be improved at the cost of degraded performance; however, the performance of large MIMO system is not an issue because of the availability of very large antennas at the transmitter and receiver. The expression for the moment generating function (MGF) of the received signal-to-noise ratio at the receiver node is derived for the proposed OSTBC-based scheme. Using the MGF expression, we obtain the analytical symbol error rate for the proposed scheme with M-ary phase-shift keying modulation symbols.

OSTBC Transmission in Shadowed-Rician Land Mobile Satellite Links

In this paper, we study the transmission of orthogonal space–time block codes (OSTBCs) over a shadowed Rician (SR) land mobile satellite (LMS) link. Specifically, we derive the symbol error rate (SER), diversity order, and the average capacity of the OSTBC-transmission-based scheme over the SR fading LMS communication systems. First, we consider the independent and identically distributed (i.i.d.) SR fading channels and derive the expressions of moment-generating function (mgf) in terms of the Meijer-G function. By substituting the Meijer-G function in terms of hypergeometric function and then by considering the asymptotic approximation of hypergeometric function, the analytical diversity order of the scheme is obtained. The ergodic capacity of the scheme is derived by using the mgf-based approach. The effect of elevation angles over the SER performance of the scheme is analyzed, and it is observed that the performance of the system is improved with increasing values of elevation angles. Next, we consider the OSTBC transmission over correlated SR fading channels and derive the expressions of mgf, SER, diversity order, and average capacity of the considered setup. In particular, it is demonstrated in this paper that, by employing an additional transmit antenna at the satellite along with Alamouti code, the error rate of the LMS communication system can be significantly improved. It is also shown that the correlation has no impact on the diversity order of the system, but it adversely affects the capacity of the system.

OSTBC transmission in MIMO AF relaying with M-FSK modulation

This paper investigates orthogonal space-time block code (OSTBC) transmission for multiple-input multiple-output (MIMO) amplify-and-forward (AF) relaying networks composed of one source, K relays, and one destination and with M-ary frequency-shift keying (FSK) modulation. A non-coherent detection scheme is proposed and analyzed in a situation where the fading channels undergo temporal correlation. Specifically, by properly exploiting the implicit pilot-symbol-assist property of FSK transmission, the destination estimates the overall channels based on the linear minimum mean square error (LMMSE) estimation algorithm. It then utilizes the maximal ratio combining (MRC) to detect the transmitted information. An upper bound on the probability of errors is derived for a network with arbitrary numbers of transceiver antennas and relays. Based on the obtained bit error rate, the full achievable diversity order is verified. Simulation results are presented to show the validity of the analytical results.

Bandwidth Efficient Variable Rate HARQ Under Orthogonal Space-Time Block Codes

We propose a bandwidth and power efficient hybrid Automatic Repeat reQuest (HARQ) transceiver system that preserves full retransmission diversity under orthogonal space-time block codes (OSTBC) with low decoding complexity. This new HARQ scheme is built upon traditional OSTBC transmission to achieve full space-time diversity. During retransmissions upon packet losses, space-time encoding can be compressed in time to reduce bandwidth utility and achieve joint detection of multiple transmissions without training. By formulating the joint detection model at the receiver into a Quasi-Orthogonal Space-Time transmission, we can achieve the dual objectives of bandwidth reduction and full transmission diversity. Unlike traditional full ARQ retransmission, our proposed receiver can also apply joint semi-blind channel estimation by omitting training during retransmission to further improve bandwidth efficiency.

Outage Analysis of Orthogonal Space–Time Block Code Transmission in Cognitive Relay Networks With Multiple Antennas

The outage performance of cognitive relay networks (CRNs) for a decode-and-forward (DF) protocol in a spectrum sharing scenario with orthogonal space-time block code (OSTBC) transmission is presented in this paper. Both the exact formulas of the outage probability and its approximation in a high-SNR region are derived over Rayleigh fading channels. The theoretical results are validated by simulations. It shows that there is an outage saturation phenomenon due to both the maximum transmit power limit and the interference power constraint, which is similar to CRNs with a single antenna. Meanwhile, our results also show that increasing the number of antennas may not improve the outage performance when the interference power constraint or the transmit power constraint is very small; however, it will significantly improve the outage performance when the number of antennas is large enough. Through the asymptotic analysis, it shows that the CRN where the source and the relay are both equipped with N antennas can achieve full degree of diversity, i.e., 2N-order diversity.

Cooperative decode‐and‐forward relaying with orthogonal space–time block code over doubly correlated Nakagami‐ m fading channels

In this study, the authors investigate the performance of cooperative decode-and-forward multiple-input multiple-output relaying system with orthogonal space–time block code transmissions over doubly correlated Nakagami-m fading channels, where the source, relay and destination nodes are all equipped with multiple antennas. They also include correlated and independent Rayleigh fading channels as special cases. Only when the relay node could receive the signal from the source correctly, it will forward source information to the destination. For two types of receivers at the destination, maximal ratio combining and selection combining, the authors provide the compact closed-form expressions for cumulative distribution function (CDF) and probability density function of the instantaneous end-to-end signal-to-noise ratio (SNR). Besides, the exact analytical expressions are also derived for the outage probability (OP) and symbol error rate (SER) relying on CDF. Furthermore, they present the asymptotic expressions for OP and SER in the high SNR regime, from which they gain an insight into the system performance and derive the achievable diversity order and array gain. The analytical expressions are validated by Monte-Carlo simulations.

Dual-hop MIMO relaying with OSTBC over doubly-correlated Nakagami-m fading channels

In this article, we investigate the performance of dual-hop amplify-and-forward multiple-input multiple-output relaying system with orthogonal space-time block code transmissions over doubly-correlated Nakagami-m fading channel, where the source, relay, and destination terminals are all equipped with multiple antennas. For two different CSI-assisted relaying schemes, which could be encompassed by a unified model, we provide the compact closed-form expressions for cumulative distribution function, probability density function, moment generating function, and generalized moment (GM) of the instantaneous end-to-end SNR. Besides, the exact analytical expressions for the outage probability (OP) and symbol error rate (SER) and approximate expression for ergodic capacity are also derived. Furthermore, we present the asymptotic expressions for OP and SER in the high SNR regime, from which we gain an insight into the system performance and derive the achievable diversity order and array gain. The analytical expressions are validated by Monte-Carlo simulations.

Performance Analysis of Decouple-and-Forward MIMO Relaying in Nakagami-<i>m</i> Fading

The end-to-end performance of dual-hop multiple-input multiple-output (MIMO) decouple-and-forward relaying with orthogonal space-time block code (OSTBC) transmission over Nakagami-m fading is analyzed. By considering the multiple antennas at all nodes, we derive exact closed-form and asymptotic expressions for the outage probability and symbol error rate, which enables us to evaluate the exact performance and reveals the diversity gains of the considered system. In addition, the closedform approximation and asymptotic expressions for the ergodic capacity are also derived. We show that OSTBC transmission over relay systems yields a unit order of multiplexing gain despite the fact that full diversity order, which is equal to the minimum fading severity between the two hops, is achieved.

Outage performance of orthogonal space–time block code transmission in opportunistic decode‐and‐forward cooperative networks

ABSTRACTOutage performance is analyzed for opportunistic decode‐and‐forward cooperative networks employing orthogonal space–time block codes. The closed‐form expressions of diversity order and the end‐to‐end outage probability at high signal‐to‐noise ratio regime are derived for arbitrary relay number (K) and antenna configuration (N antennas at the source and each relay, ND antennas at the destination) under independent but not necessarily identical Rayleigh fading channels. The analysis is carried out in terms of the availability of the direct link between the source and the destination. It is demonstrated that the diversity order is min{N, ND} ⋅ KN if the direct link is blocked, and if the direct link is available, the diversity order becomes min{N, ND} ⋅ KN + NND. Simulation and numerical results verify the analysis well. Copyright © 2011 John Wiley & Sons, Ltd.

Outage Performance of Heterogeneous MIMO Relaying in OSTBC Transmission over Spatially Correlated Nakagami Fading Channels

In this letter, we investigate a heterogeneous multi-hop relaying system in which relay nodes (RNs) use different relaying methods due to the different versions or the cost structure of deployed RN equipments. Especially, we provide the outage performance of heterogeneous multiple-input multiple-output (MIMO) relaying of orthogonal space-time block code (OSTBC) transmission for spatially correlated Nakagami fading channels. In this letter, the heterogeneous RNs are comprised of decouple-and-forward (DCF) and decode-and-forward (DF) relays. The outage probability is obtained by assuming an ideal amplifying gain for DCF relaying and then verified with numerical investigation. The numerical results also show the impact of various combinations of DCF and DF RNs on the outage performance.

Peroformance analysis of decode-and-forward MIMO relay channels with OSTBCs

Performance analysis is presented for multiple-input multiple-output (MIMO) relay channels employing transmit antenna diversity with orthogonal space-time block codes (OSTBCs), where the source and the destination are equipped with N s and N d antennas, and communicate with each other with the help of a multiple-antenna relay operating in decode-and-forward (DF) mode. Over independent, not necessarily identical Rayleigh fading channels, exact closed-form symbol error rate (SER) expressions are derived for various digital modulation formats for both the OSTBC transmission with and without the direct link. The moment generating functions (MGFs) for overall system signal-noise ratios (SNRs) are also derived, based on which we present a unified SER analysis. The analysis shows that full spatial diversity order can be achieved for the DF MIMO relay channel by adopting OSTBC transmissions and maximal ratio combining (MRC) receptions. All the analytical results are confirmed through comparison with the results obtained using Mento Carlo simulations.

Performance Analysis of Two-Hop OSTBC Transmission over Rayleigh Fading Channels

A two-hop amplify and forward (AF) relay system is considered where source and destination are each equipped with multiple antennas while the relay has a single antenna. Orthogonal space-time block coding (OSTBC) is employed at the source. New exact expressions for outage probability in Rayleigh fading as well as symbol error rate (SER) expressions for a variety of modulation schemes are derived. The diversity order of the system is evaluated. Monte Carlo simulations demonstrate the accuracy of the analyses presented. Results that can be extended to relay systems with a direct source-destination link are also highlighted. To put the results in context, the two-hop system performance is then compared to that of a MIMO point-to-point system. Finally, the new analysis is applied to evaluate two-hop system performance as a function of relay location.

Achieving maximum spatial diversity with decouple-and-forward relaying in dual-hop OSTBC transmissions

In this letter, we prove that decouple-and-forward (DCF) relaying for dual-hop orthogonal space-time block code (OSTBC) transmissions achieves the maximum diversity order attainable by dual-hop MIMO relaying systems. Decoupling at the relay transforms received OSTBC signals into independent and maximal-ratio combined single-input single-output (SISO) signals, which provides the receive diversity gain, and also enables the relay to use OSTBCs again so as to achieve the transmit diversity gain. In obtaining the diversity order, DCF relaying needs a coherence interval of the length of OSTBC transmissions, which is shorter than the requirement assumed in other works that provide the maximum diversity. Numerical results are also presented to verify the proof and give an insight to the relationship between the diversity order and antenna configurations.

Performance Analysis of OSTBC Transmission in Amplify-and-Forward Cooperative Relay Networks

A performance analysis is presented for amplify-and-forward (AF) cooperative relay networks employing transmit antenna diversity with orthogonal space-time block codes (OSTBCs), where multiple antennas are equipped at the transmitter. We develop a symbol-error-rate (SER) and outage performance analysis for OSTBC transmissions with and without cooperative diversity over flat Rayleigh fading channels. We first derive exact probability density functions (pdf's) and cumulative distribution functions (cdf's) for the system SNR without direct transmission with an arbitrary number of transmit antennas and then present the exact closed-form SER and outage probability expressions. Next, we derive the moment-generating function (MGF) for the overall system SNR with direct transmission and present the exact SER and outage probability with joint transmit antenna diversity and cooperative diversity. The theoretical analysis is validated by simulations, which indicate an exact match between them. The results also show how the transmit antenna diversity and the cooperative diversity affect the overall system performance.