Alamouti Space-time Block Code Research Articles

MGF Based Approximate SER Calculation of SM MIMO Systems Over Generalized η − μ and κ − μ Fading Channels

Spatial modulation (SM) is a multiple input multiple output (MIMO) wireless communication system that gives better spectral efficiency without costing extra bandwith for the same signal constellation size. In an SM MIMO system with $$N_t$$Nt transmitting antennas, spectral efficiency increases by $$log_2(N_t)$$log2(Nt). The superior performance of SM systems over other MIMO systems like Alamouti Space-Time Block Codes and Vertical Bell Laboratories Layered Space-Time is already reported in the literature. In this paper, we analyzed the symbol error rate (SER) performance of an SM system in generalized $$\eta-\mu $$?-μ and $$\kappa - \mu $$?-μ fading channels for several modulation schemes. A closed form expression for approximate SER is derived using moment generating function (MGF) approach and the results are validated using Monte Carlo simulations. The approximate SER expression obtained in this communication is applicable for any fading channels whose MGF is known. The SER analysis over generalized fading channels can be easily deduced to various classical fading channels like Rayleigh, Rician, Nakagami-m and Nakagami-q fading channels by choosing appropriate values of $$\kappa $$?, $$\mu $$μ and $$\eta $$?.

Performance analysis of two-user cooperative ARQ protocol over Rayleigh fading channel

In this paper, we present a two-user cooperative automatic repeat request (C-ARQ) protocol which combines cooperative diversity at the physical layer and ARQ at the link layer. In this scheme, distributed Alamouti space-time block coding (DASTBC) is applied to achieve cooperative diversity, and ARQ is used to improve the data link layer reliability. To analyze the performance of the proposed protocol, we derive the average frame error rate (FER) and throughput with multiple phase shift keying (MPSK) over a Rayleigh fading channel. Numerical simulation results show that the performance gain of average FER with ARQ retransmission is about 2 dB more than the case without ARQ retransmission in the same conditions. Moreover, the combined DASTBC and quadrature phase shift keying (QPSK) with ARQ retransmission will lead to an approximate 3 Mbits/s increase in transmission rate.

A Novel Strategy for Performance Improvement of MISO Wireless System using Alamouti STBC with 4th order FIR Filter

wireless communication system is highly desirable field among the researchers these days because of the increasing demand of high speed of networks to serve on the next generation mobile devices. The various researches already completed but the reliability like leased line hasn't achieved yet. The end to end performance of the system still needs to be improved. In this paper same we are trying to improve. The figure of merit is Bit Error Rate (BER). The proposed approach depends on multiple input single output (MISO) system which significantly improves the performance. Now to improve more the Alamouti STBC with 4th Order FIR filter is implemented. The filtering approach have changed picture of the system by reducing the error probability. BER performance achieved in this paper is better than existing work.

Space-Time-Coded Adaptive Spatial Modulation in Wireless MIMO Communication Systems

AbstractIn this paper, we consider a wireless multi-antenna system using a promising technique, i.e., spatial modulation, and propose an adaptive spatial modulation (ASM) scheme embedded Alamouti space-time block coding (STBC). Instead of selecting one active antenna in each transmission in conventional ASM, we activate two antennas as one antenna group simultaneously to encode the information bits into Alamouti code blocks, each of which needs two channels used. Two detection schemes are presented in different channel conditions, i.e., the maximum likelihood (ML) detection and an adaptive modulation-order selection algorithm. Simulation results show that the proposed scheme improves the error performance and provides larger diversity gain compared to conventional spatial modulation and adaptive spatial modulation.

UAV Channel Estimation with STBC in MIMO Systems

Abstract The combination of coding with spatial diversity opens up new dimensions in wireless communications with emphasize to Unmanned Aerial Vehicles (UAVs), and can offer effective solutions for wireless communication channels. Application of Alamouti Space-Time Block Codes (STBCs) with diversity with multiple antennas provide improved performance in faded wireless channels. Alamouti transmit diversity scheme, however, relies on the availability of accurate Channel State Information (CSI). This paper proposes a channel estimation method based on Kalman filter with STBC codes and multiple antenna systems, namely Multiple-Input Single-Output (MISO) and Multiple-Input Multiple-Output (MIMO) systems. Simulations have been done in time-varying Rayleigh faded channels for BPSK and QPSK. The proposed technique seems to obtain an error performance closer to that of a known channel information case in severely faded channel considerations.

Simple unequal error protection mechanism for multimedia traffic using the Alamouti structure with hierarchical modulation and signal space diversity

Conventional hierarchical modulation (HM) only provides two levels of unequal error protection (UEP) for multimedia traffic transmission. An HM-based scheme is proposed that provides multiple levels of UEP by exploiting the structure of the Alamouti scheme. A typical Alamouti scheme operates based on the assumptions that the modulation scheme used for the transmission at each antenna is the same and that the power in each antenna is equal. In the proposed system, these two operating assumptions are relaxed, in that the modulation schemes as well as the transmission powers for the two antennas are varied in order to propose a multiple level UEP mechanism for multimedia traffic. The concept is applied to a recently proposed system which uses the Alamouti space–time block code (STBC) structure with HM and signal space diversity (SSD), and it is shown via theoretical and simulation results how the simple UEP mechanism can accommodate the simultaneous transmission of multiple classes of multimedia traffic.

Soft‐output space‐time block coded spatial modulation

Space-time block coded spatial modulation (STBC-SM) is a recently proposed multiple-input–multiple-output transmission scheme, which combines spatial modulation (SM) and Alamouti's space-time block code (STBC) in such a manner so as to retain the primary advantages of SM and STBC, while avoiding their drawbacks, resulting in an improved system error performance. In this study, the authors propose a soft-output maximum-likelihood (ML) detector (SOMLD) and a soft-output low-complexity near-ML detector (SOLCD) for STBC-SM transmission. Monte-Carlo simulations demonstrate that the error performance of the proposed schemes are able to closely match that of the hard decision ML detector for uncoded channel conditions, while significant improvement in error performance is demonstrated for coded systems. Furthermore, compared with SOMLD, SOLCD imposes a significantly lower computational complexity, while achieving near-ML error performance.

English

In this paper, an analysis for the bit error rate (BER) performance of space-time block codes (STBC) from generalized orthogonal designs for QAM modulation has been presented. Space-time block codes (STBC) offer high diversity gain and among which orthogonal STBCs are very attractive due to its relatively simpler design and low decoding complexity. Performance of Alamouti STBC and Orthogonal STBC with rate ½ for different transmitting and receiving antennas under Rayleigh fading situation has been analyzed. The decoding techniques used for this analysis are ZF, MMSE and ML. In all the cases, the bit error rate has been treated as the figure of merit and its change with SNR are observed due to different parameter variations of the channel distribution as well as different antenna configurations.

Blind Identification of Spatial Multiplexing and Alamouti Space-Time Block Code via Kolmogorov-Smirnov (K-S) Test

A novel algorithm for blind identification of spatial multiplexing and Alamouti space-time block code is proposed in this paper. It relies on the Kolmogrov-Smirnov test, and employs the maximum distance between the empirical cumulative distribution functions of two statistics derived from the received signal. The proposed algorithm does not require estimation of the channel coefficients, noise statistics and modulation type, and is robust to the carrier frequency offset and impulsive noise. Additionally, it outperforms the algorithms in the literature under a variety of transmission impairments.

Block-Wise QR-Decomposition for the Layered and Hybrid Alamouti STBC MIMO Systems: Algorithms and Hardware Architectures

Unlike the channel matrix in the spatial division multiplexing (SDM) multiple-input multiple-output (MIMO) communication system, the equivalent channel matrix in the layered Alamouti space-time block coding (STBC) MIMO system comprised 2-by-2 Alamouti sub-blocks. One novel property, found by Sayed about the QR-decomposition (QRD) of this equivalent channel matrix is that the produced Q- and R-matrices are also matrices with Alamouti sub-blocks. Taking advantage of this property, we propose a new block-wise complex Givens rotation (BCGR) based algorithm and a triangular systolic array (TSA) to compute the QRD of the equivalent channel matrix in an Alamouti block by block manner. Implementation results reveal that our new TSA can compute QRDs of 4-by-4 equivalent channel matrices faster than any architecture that has been developed for the SDM MIMO system. This property of fast QRD makes our TSA very attractive for the layered Alamouti STBC MIMO system combined with the orthogonal frequency division multiplexing. Our new BCGR based approach can also be applied to the hybrid Alamouti STBC MIMO system, which is also a system with equivalent channel matrix consisting of Alamouti sub-blocks.

Outage probability analysis of space–time block coding‐orthogonal frequency division multiplexing cooperative systems

In this study, the performance of a multi-carrier (MC) multi-relay system with multi-antenna at source and destination nodes is investigated based on Alamouti space–time block coding (STBC) and amplify-and-forward (AF) cooperative diversity protocol with different schemes. In particular, transmission of each STBC in the system is initiated by signal broadcasting from the source node to the destination node and all the relay nodes. Depending on the cooperative scheme, one or more relays, applying AF protocol, transmit the signal to the destination. Applying maximum ratio combination technique to both the direct and the relayed subcarriers at the destination, the outage probability bounds are analytically derived for various schemes of relaying. Simulation results confirm the validity of the derived bounds, and show that the cooperative MC-multiple-input–multiple-output channel yields a notable outage performance with an acceptable capacity, especially in the average best relay selection scheme, which exploits the limited feedback.

Performance Analysis by Improving Bit Error Rate (BER) through various Diversity Techniques in Wireless Communication

In wireless communication systems antenna diversity is an important technique to combat deep fading to improve the system performance and to increase the channel capacity. The fast and random fluctuation of the received signal strength is usually called fading. Diversity technique has been taken into consideration to mitigate the effects of fading by generating several copies of the signal, which experience independent or estimated independent fading, to decrease the probability of instantaneous deep fades. This paper presents the performance analysis of a system in various diversity mechanism environments by improving bit error rate (BER). General Terms Diversity Techniques Keywords BPSK modulation, Bit Error Rate(BER), Rayleigh Channel,MRC,Selective Combining(SC), Equal Gain Combining (EGC),Beamforming Technique, Alamouti STBC Technique

High Rate Space-Time Block Coded Spatial Modulation with Cyclic Structure

A high rate space-time block coded spatial modulation scheme with cyclic structure (STBC-CSM) is presented in this letter. In the proposed STBC-CSM scheme, a pair of transmit antennas are chosen out of the total transmit antennas to send Alamouti's STBC, whose two signal symbols are drawn from two different constellations, and the antenna pairs activated in different codewords are moving cyclically along the total transmit antenna array. To exploit the diversity advantage of Alamouti's STBC, the optimization of STBC-CSM is given by maximizing its coding gain. Moreover, the proposed scheme allows for a low-complexity maximum-likelihood (ML) detector due to the orthogonality of Alamouti's STBC. The simulation results verify our theoretical analysis and demonstrate the performance advantages of our proposed STBC-CSM over the existing schemes such as STBC-SM, H-STBC-SM, CIOD-SM-H and SM.

English

In this paper we analyze the performance of 2by3 MIMOMCCDMA system in MATLAB which greatly reduces BER by increasing the efficiency of system. MIMO and MCCDMA system arrangement is used to decrease bit error rate and also figure a new system called MCCDMA which is multiple user and multiple access system used to enhance the performance of the system. MCCDMA is a narrowband flat fading in character which changes frequency selective to several narrowband flat fading multiple parallel subcarriers to enhance the effectiveness of the system. Now this MCCDMA further improved by grouping by 2by3 MIMO system which make use of ZF decoder at the receiver to reduce BER in which half rate convolutional encoded Alamouti STBC block code is intended for channel encoding as transmit diversity for MIMO with multiple transmit and receive antennas. Main improvement of using MIMOMCCDMA is for reducing complication of system and also for dropping BER and finally increasing gain of the system. Then we estimate the system in different modulation techniques like, 64QAM, 8PSK, 16QAM, QPSK, 32QAM and 8QAM using MATLAB in Rayleigh fading channel.

English

In this paper we estimate the performance of 2by3 MIMOMCCDMA system using convolution code in MATLAB which highly reduces BER by increasing the efficiency of system. MIMO and MCCDMA system combination is used to reduce bit error rate and also for forming a new system called MCCDMA which is multi user and multiple access schemes used to increase the performance of the system. MCCDMA system is a narrowband flat fading in nature which converts frequency selective to numerous narrowband flat fading multiple parallel sub-carriers to increase the efficiency of the system. Now this MCCDMA system can also be enhanced by grouping with 2by3 MIMO system which utilizes ZF decoder at the receiver to decrease BER in which half rate convolutionally encoded Alamouti STBC block code is used for channel encoding scheme as transmit diversity of MIMO with multiple transmit antenna. And convolution encoder is also used as source encoder or FEC encoder in MIMOMCCDMA. Advantage of using MIMO-MC-CDMA using convolution code is due to reduce complexity of system and also for reducing BER and finally to increase gain of system. Now after this we examine system in various modulation techniques like, 8PSK, 16QAM, QPSK, 32QAM, 8QAM and 64QAM using MATLAB in Rayleigh fading channel.

Single-Carrier Space Time Transmission Diversity with Decision Feedback Equalization

In order to suppress inter-symbol interference (ISI), the Frequency domain decision feedback equalization (FD-DFE) algorithm is proposed in this paper for single carrier frequency domain equalization (SC-FDE) combined with Alamouti space time block coding (STBC) systems over frequency-selective channels. We use the cyclic prefix (CP) and two transmit antennas to achieve the significant diversity gain. The feedback equalization part is designed by Mean Square Error (MSE) criterion and the coefficients of filters are all in the frequency domain for the given channel frequency response. The outage and diversity analysis of system is also made to measure the equalization performance. Finally, the simulation results show that the proposed algorithm has better performance than the conventional liner equalization (LE) and hybrid structure decision feedback equalization (HDFE) schemes, and the computational complexity of our method is acceptable.

Distributed Space-Time Code with Mutual Information Based Soft Information Relaying

In this letter, we investigate a distributed space-time coded soft information relaying. In particular, we focus on mutual information based soft forwarding (MIF) scheme with Alamouti space-time block code. In order to achieve a full diversity order, we propose a weighted amplifying factor based on average soft noise variance instead of instantaneous one. The exact analytical expression for average soft noise variance is first derived. A tight upper bound of the average soft noise variance is also derived in closed-form. It is shown that the proposed distributed MIF Alamouti scheme can achieve a full diversity order, and outperforms various distributed Alamouti schemes reported in the literature.

Joint Estimation of Transmitter and Receiver IQ Imbalance With ML Detection for Alamouti OFDM Systems

The application of multiple transmit antennas in orthogonal frequency-division multiplexing (OFDM) systems provides better spectral efficiency with high performance gain. However, these systems are very sensitive to channel estimation errors and analog front-end impairments, such as in-phase/quadrature-phase (IQ) imbalance. To ensure a reliable transmission, the channel impulse response (CIR) and IQ imbalance have to be accurately estimated. Unlike previous work, we show that the unwanted IQ imbalance can be exploited to achieve a diversity gain. This paper develops a maximum-likelihood (ML) detector by exploiting the diversity gain resulting from the IQ imbalance for Alamouti space-time block code OFDM systems. Moreover, we propose a novel iterative algorithm to jointly estimate the CIR and IQ imbalance occurring at both the transmitter and the receiver. We initially employ a pilot sequence for estimation and detection. Then, we exploit the soft information provided by the detector via an expectation-maximization (EM) algorithm to improve the estimation efficiency iteratively. To reduce the computational complexity of the estimation process, a suboptimal algorithm is also developed. Simulation results indicate that the bit-error-rate (BER) performance of the proposed detector in conjunction with the proposed estimation algorithms is very close to the BER of the perfectly known parameters case with a diversity gain resulting from the IQ imbalance.

Fourth-Order Statistics for Blind Classification of Spatial Multiplexing and Alamouti Space-Time Block Code Signals

Blind signal classification, a major task of intelligent receivers, has important civilian and military applications. This problem becomes more challenging in multi-antenna scenarios due to the diverse transmission schemes that can be employed, e.g., spatial multiplexing (SM) and space-time block codes (STBCs). This paper presents a class of novel algorithms for blind classification of SM and Alamouti STBC (AL-STBC) transmissions. Unlike the prior art, we show that signal classification can be performed using a single receive antenna by taking advantage of the space-time redundancy. The first proposed algorithm relies on the fourth-order moment as a discriminating feature and employs the likelihood ratio test for achieving maximum average probability of correct classification. This requires knowledge of the channel coefficients, modulation type, and noise power. To avoid this drawback, three algorithms have been further developed. Their common idea is that the discrete Fourier transform of the fourth-order lag product exhibits peaks at certain frequencies for the AL-STBC signals, but not for the SM signals, and thus, provides the basis of a useful discriminating feature for signal classification. The effectiveness of these algorithms has been demonstrated in extensive simulation experiments, where a Nakagami-m fading channel and the presence of timing and frequency offsets are assumed.

A Novel Blind Block Timing and Frequency Synchronization Algorithm for Alamouti STBC

Blind estimation algorithms have attracted considerable attention due to their potential applications in bandwidth efficient communications systems, such as the provision of spectrum awareness in cognitive radios. This paper proposes a blind block timing and frequency synchronization algorithm applicable to the Alamouti space-time block code in the context of Nakagami fading channels. The proposed algorithm exploits the space-time redundancy of the received signal to estimate the signal synchronization parameters using a single receive antenna. It has low sensitivity to clock timing synchronization errors and does not require knowledge of the channel coefficients, signal-to-noise ratio, and the modulation of the received signal. Computer simulations have confirmed that the algorithm has low sensitivity to clock timing synchronization errors and is suitable for use over Nakagami fading channels.