Orthogonal Space-time Block Codes Research Articles

Employment of Generalized Receiver in DS-CDMA with STBC over Fading Channels: Capacity and Error Probability

The capacity and error probability of orthogonal space-time block codes (STBCs) are considered for the pulse-amplitude modulation (PAM), phase shift keying (PSK), quadrature-amplitude modulation (QAM) in fading channels. The suggested approach is based on employment of the generalized approach to signal processing in noise over the equivalent scalar additive white Gaussian noise channel with a channel gain proportional to the Frobenius norm of the matrix channel for the STBC. Using this effective channel, the capacity and probability of error expressions are derived for the PSK, PAM, and QAM modulation with space-time block coding. The Rayleigh, Rician and Nakagami fading channels are considered. As an application, these results are extended to obtain the capacity and probability of error for a multiuser direct sequence code-division multiple-access (CDMA) system constructed on the basis of the generalized approach to signal processing in noise employing the space-time block coding.

Signal Processing by Generalized Receiver Using DS-CDMA with STBC Technology in Multidimensional Systems over Fading Channels: Capacity and Error Probability

The capacity and error probability of orthogonal space-time block codes (STBCs) are considered for the pulse-amplitude modulation (PAM), phase shift keying (PSK), quadrature-amplitude modulation (QAM) in fading channels. The suggested approach is based on employment of the generalized approach to signal processing in noise over the equivalent scalar additive white Gaussian noise channel with a channel gain proportional to the Frobenius norm of the matrix channel for the STBC. Using this effective channel, the capacity and probability of error expressions are derived for the PSK, PAM, and QAM modulation with space-time block coding. The Rayleigh, Rician and Nakagami fading channels are considered. As an application, these results are extended to obtain the capacity and probability of error for a multiuser direct sequence code-division multiple-access (CDMA) system constructed on the basis of the generalized approach to signal processing in noise employing the space-time block coding

A novel method for improving Bit Error Rate in sensor networks by using Orthogonal Space Time Block Code (OSTBC) coding

For the designing of any network, lifetime and size of the network are the most important parameters in addition to that high data rate and low bit error rate also play an important role in the designing of any sensor network. In this paper, new transmission techniques for the transmission of sensors data has been proposed for sensor networks by combining various modulation and coding techniques into the network transmission. The proposed technique is used to improve the Bit Error Rate performance of the wireless sensor network, in most of the wireless sensor networks ,bits are converted into packets and these packets are transmitted from source to destination during that transmission the quality of physical layer is determined by the Bit Error Rate (BER) and the Packet Delivery Rate (PDR). The physical layer deals with transmission of bits over wireless link the designing constraints of this layer is modulation, diversity and coding. In this paper various modulation, coding and diversity techniques are incorporated into sensor network for reducing Bit Error Rate (BER). The proposed system divides the network into two types of nodes, first one is the sensor nodes, equipped with short distance transmission capability and another one is special nodes that are equipped with modulators and coders for transmitting data over long distance. This proposed system also extended for providing the secured data transmission by the use of various error detection and correction codes.

Performance Analysis of OSTBC-NOMA System in the Presence of Practical Impairments

This paper investigates the performance of a power-domain downlink non-orthogonal multiple access (NOMA) system in the presence of practical impairments such as channel estimation error (CEE), feedback delay (FBD) and imperfect successive interference cancellation (SIC), where the base station communicates with multiple users by applying orthogonal space-time block coding (OSTBC) technique in order to exploit the benefits of transmit diversity. Outage probability (OP), ergodic capacity and fairness index analyses are conducted in case channels are subjected to Nakagami-m fading in order to illustrate the level of system performance, and closed-form mathematical expressions are obtained. Furthermore, to demonstrate the impact of CEE and FBD, asymptotic OP is also maintained. The analytical results validated by Monte Carlo simulations demonstrate that all performance metrics reach a non-zero fixed value in high signal-to-noise region due to the CEE and FBD while imperfect SIC worsens the performance of user with the lowest power allocation to the full outage. In addition, NOMA outperforms its counterpart orthogonal multiple access in terms of OP and ergodic capacity generally. Also, G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -OSTBC code has higher fairness index than G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -OSTBC code.

СИНТЕЗ СПЕКТРАЛЬНО ТА ЕНЕРГЕТИЧНО-ЕФЕКТИВНИХ СИГНАЛЬНО-КОДОВИХ КОНСТРУКЦІЙ ДЛЯ СИСТЕМ МІМО З ПРОСТОРОВИМ КОДУВАННЯМ СИГНАЛІВ

Wireless communication systems are considered, the main task of which is to increase their spectral (SE) and energy efficiency (EE) in conditions of limited frequency and energy resources. Additional use of the spatial resource based on flexible and universal methods of signals Space-Time Coding (STC) in MIMO-systems (Multiple Input - Multiple Output) can significantly increase the SE and EE values, as well as significantly improve the capabilities and conditions for EE exchange on SE. The advantages and disadvantages of Orthogonal Space-Time Block Coding (OSTBC) and Non-Orthogonal STBC (NOSTBC) are shown. Two main methods of synthesis of spectrally and energy-efficient information transmission methods are demonstrated. The first method is implemented by creating Perfect-codes that simultaneously achieve maximum diversity and multiplexing gains. The exponential computational decoding complexity of such codes makes it impossible for their practical implementation in mobile terminals at the present stage of development of circuitry. The second method of synthesis is based on improving the simple basic STC methods in terms of increasing the SE and EE by creating Signal-Code Constructions (SCC), which have the advantages of the basic STC methods and are devoid of the disadvantages inherent in Perfect-codes. A technique for the synthesis of SCC is proposed, the essence of which is to determine the priority areas (by the value of the Signal-to-Noise Ratio (SNR)) of using the STC and corresponding signal constellations, which provide the maximum SE for a guaranteed Bit Error Rate (BER). It was found that MIMO 2x2 with Alamouti OSTBC has an advantage in terms of EE over NOSTBC type VBLAST for SE not more than 8 b/s/Hz and SNR under 35 dB, BER not exceeding 10-5. In MIMO 4x4, OSTBC codes are inferior to NOSTBC in terms of EE. VBLAST code allows to provide SE 4 - 8 b/s/Hz at SNR 10 - 20 dB, BER not exceeding 10-5. Based on the results obtained, propositions for further improvement of OSTBC and NOSTBC are formulated.

Analysis and outage performance evaluation of a fair scheduling for independent non‐identically distributed users in a cognitive radio using OSTBC with equally correlated transmit antennas

In this study, a fair user-scheduling method is considered for an underlay cognitive radio system, in which the secondary users (SUs) are sharing the licenced frequency spectrum of a single primary user (PU), where the PU and SUs utilise Alamouti orthogonal space-time block coding (OSTBC). The impacts of some important practical issues are investigated in the system. First, it is assumed that the signal-to-noise-ratios of the SUs are independent non-identically distributed. Second, the transmit antennas for OSTBC corresponding to the SUs are assumed to be equally correlated. Third, the interference from the PU to SUs as well as the interferences from SUs to the PU are taken into consideration. To investigate the outage performance of the SUs, a closed-form expression for the cumulative distribution function of the SUs signal-to-interference-noise-ratio is obtained and then used to derive an expression for evaluating the secondary system outage performance. The numerically evaluated results, validated by computer simulations, provide insights about system outage performance under various practical situations on the impacts of the spatial antennas correlation and the PU interference on to SUs.

Sparse Doubly-Selective Channel Estimation Techniques for OSTBC MIMO-OFDM Systems: A Hierarchical Bayesian Kalman Filter Based Approach

Hierarchical Bayesian Kalman filter (HBKF) based schemes are conceived for doubly-selective sparse channel estimation in orthogonal space-time block coded (OSTBC) multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) wireless systems. Initially, a pilot based multiple measurement vector (MMV) model is formulated for estimating the OSTBC MIMO-OFDM channel. This is followed by the development of a low-complexity, online pilot-based HBKF (P-HBKF) scheme for tracking the sparse time-varying frequency-selective channel. The salient advantages of the proposed P-HBKF technique are that it requires significantly lower number of pilot subcarriers, while also exploiting the inherent sparsity of the wireless channel. Subsequently, data detection is also incorporated in the proposed framework, leading to the development of a procedure for joint sparse doubly-selective channel estimation and symbol detection. Recursive Bayesian Cramér-Rao bounds and closed form expressions are also obtained for the asymptotic mean square error (MSE) based on the solution of the Riccati equation for the KF for benchmarking the performance. Simulation results are presented for validating the theoretical bounds and for comparing the performance of the proposed and existing techniques.

Generalized Space Time Block Coded Spatial Modulation for Open-Loop Massive MIMO Downlink Communication Systems

In this paper, we propose a generalized space-time block coded spatial modulation (GSTBC-SM) scheme for open-loop massive multiple-input and multiple-output (MIMO) downlink communication systems. Specifically, we firstly partition the information bits into multiple groups with each group modulated by the spatial modulation (SM), where the SM symbols are invoked for orthogonal STBC (OSTBC) and quasi-orthogonal STBC (Q-OSTBC) structures. Then, message passing (MP) and block minimum mean square equalization (B-MMSE) detectors are designed for our GSTBC-SM systems, to achieve near-optimal performance with significantly reduced complexity in massive MIMO configurations. Finally, we derive the theoretical average bit error probability (ABEP) of the proposed scheme. The main contribution is that the propose scheme achieves high transmission rate and diversity gain even with small number of radio frequency (RF) chains at the transmitter. Simulation results verify the theoretical derivations and show that the proposed GSTBC-SM scheme provides near 20 dB gain over the conventional GSTBC scheme under massive MIMO configurations.

Physical layer security in space‐time block codes from coordinate interleaved orthogonal design

In this study, the physical layer (PHY) security performance of orthogonal space-time block coding (OSTBC) employing a coordinate interleaved orthogonal design (CIOD) is analysed and investigated using two metrics: average secrecy capacity and secrecy outage probability. It is shown that the CIOD system is superior than OSTBC in terms of secrecy outage probability. Closed-form expressions for PHY security metrics in OSTBC as well as CIOD are presented and compared. Then, an extended model of CIOD with arbitrary number of antennas is considered. Furthermore, the effects of artificial noise and imperfect channel estimation on PHY security of OSTBC and CIOD systems are investigated. The validity of theoretical expressions is verified by simulation, and it is shown that in practical cases the CIOD system has a better secrecy outage performance than that of the OSTBC system.

Hybrid forward error correction coding efficiency for MIMO-PLC with symmetric alpha-stable noise

Power line communication (PLC) medium is a very hostile environment, this is due to the fact that severe impairments adhering this means of communication, which cannot be described as a Gaussian noise. In this paper, we propose a powerful scheme to combat the impulsive noise effect and efficiently increase the transmission bit rate. The proposed technique makes use of a new hybrid coding (HC) process and a multiple input multiple output (MIMO) based orthogonal frequency division multiplexing (OFDM), namely, HC-MIMO-OFDM. The HC is mainly constructed based on the combination of convolutional codes (CC) and quasi cyclic-low density parity check codes (QC-LDPC). The HC-MIMO-OFDM stage is then followed by an orthogonal space time block code to provide more robustness under a heavy impulsive noise environment. Furthermore, the symmetric $$\alpha $$-stable model is applied to characterize the realistic PLC noise and consequently avoid the overestimation of the overall performance in such communication systems. The obtained results showed the increase improvement in performance of the bit-error-rate with the raise of the bit rate, when going from single input single output to MIMO. In addition, it has been illustrated that there was a gain when the MIMO was supplemented with only the CC and an additional gain when the HC is considered (i.e., combination of CC plus QC-LDPC coding).

Monostatic MIMO Backscatter Communications

Backscatter communications have two major antenna configurations: the bistatic configuration, in which the reader employs two different sets of antennas to transmit and receive, and the monostatic configuration, in which the reader employs one set of antennas for both transmitting and receiving. In this paper, we provide a comprehensive study on the MIMO techniques for the M × L monostatic channel. Particularly we study on the joint design of the query and the coding matrices. We show that the maximum achievable diversity order of the monostatic channel is the diversity order achieved by the block-lever unitary query and orthogonal space-time block code (BUTQ-OSTBC) design pair, which is ML 2 , exactly the half of the diversity order of the conventional MIMO channel. Then we show that uniform query, the simplest query approach, cannot achieve the maximum achievable diversity order in the monostatic channel. We generalize BUTQ-OSTBC to the general augmenting approach, and show that unitary matrix is optimal in terms of SER performance among all possible query matrices, when OSTBC is employed. The above results further indicate that in the backscatter channel, additional diversity can be obtained by varying the query signals over time slots within the channel coherent time, which is quite different from the results from the conventional MIMO channels. We verify our results by Monte Carlo simulations.

On the performance of code word diversity based quasi orthogonal space time block codes in multiple-input-multiple-output systems

In the recent past, a lot of researches have been put into designing a Multiple-Input-Multiple-Output (MIMO) system to provide multimedia services with higher quality and at higher data rate. On par with these requirements, a novel Quasi Orthogonal Space Time Block Code (QOSTBC) scheme based on code word diversity is proposed, which is a multi-dimensional approach, in this paper. The term code word diversity is coined, since the information symbols were spread across many code words in addition to traditional time and spatial spreading, without increasing transmission power and bandwidth. The receiver with perfect channel state information estimates the transmitted symbols with less probability of error, as more number of samples is available to estimate given number of symbols due to the extra diversity due to code words. The simulation results show a significant improvement in the Bit Error Rate (BER) performance of the proposed scheme when compared with the conventional schemes.

Implementation of 2x2 MIMO-OFDM System using Universal Software Radio Peripherals

Abstract: The 2x1 and 2x2 Multiple Input Multiple Output (MIMO) systems with Orthogonal Space-Time Block Code (OSTBC) are implemented using Universal Software Radio Peripherals (USRPs) and LabVIEW. Bit Error Rate (BER) is estimated and compared for both systems using different Mary Quadrature Amplitude Modulation (QAM) i.e. 4 QAM, 16 QAM, 64 QAM. The BER is reduced for a 2x2 MIMO than a 2x1. To improve spectral efficiency, Orthogonal Frequency Division Multiplexing (OFDM) is combined with MIMO configuration, known as MIMO-OFDM. 2x2 MIMO-OFDM with OSTBC is implemented with M-ary QAM and N IFFT(32, 64, 128 IFFT). Among these, better BER performance is observed for 2x2 MIMO with 64-IFFT. The MIMO-OFDM is used in Worldwide Interoperability for Microwave Access (WiMAX) which is the standard of IEEE 802.16. Index Terms: Multiple Input and Multiple Output (MIMO), Orthogonal Frequency Division Multiplexing (OFDM), Bit Error Rate (BER), Universal Software Radio Peripheral (USRP)

Analysis of secrecy outage performance of TAS–CIOD systems over wireless Rayleigh fading channels

In this paper, the physical layer (PHY) security performance for a coordinate interleaved orthogonal design (CIOD) for space–time coding system with transmit antenna selection scheme (TAS) is analyzed and evaluated. As an important performance measure for the PHY security in the wireless systems, closed-form expression is derived for the secrecy outage probability (SOP) of a CIOD space–time coding system, where transmit antennas selection is employed. Using the numerical results obtained from the derived closed-form expression, the SOP performance of the CIOD with TAS is presented and compared with that of the classical orthogonal space–time block coding (OSTBC) system, in which Alamouti coding and transmit antenna selection scheme is employed. We show that the CIOD with transmit antenna selection can provide a superior secrecy performance than the Alamouti-OSTBC system with TAS. To verify the analysis we also provide the Monte Carlo simulation results to show the accuracy of the results obtained from theoretical expressions derived in this paper.

Design and implementation of a novel unequal error protection scheme for coded MIMO systems

Mobile and wireless technologies such as Wi-Fi, WiMAX, 3G, 4G/LTE and the emerging 5G require communication of high quality videos with the limited available bandwidth. H.264/AVC and High Efficiency Video Coding (HEVC) or H.265 multimedia standards are implemented in these technologies to fulfill this requirement. Moreover, these standards achieve high error performance over wireless channels and large compression efficiency thereby optimizing channel bandwidth. Multimedia standards employ multi-class bitstreams where unequal levels of importance are assigned to the multimedia content. Consequently, the multi-class bit streams employ Unequal Error Protection (UEP) techniques to achieve optimal redundancy as well as better multimedia error performance and coding gains over wireless channels.Recently, coded Multiple-Input Multiple-Output (MIMO) systems employing Orthogonal Space-Time Block Codes (OSTBCs) have been adopted in mobile and wireless networks with the aim of maximizing spatial diversity gain without sacrificing the channel bandwidth. The problem of establishing reliable wireless communication links with high spatial diversity and coding gains for recent and future networks is a big challenge for researchers. A thorough literature survey reveals that the transmission of HEVC multi-class coded data streams over wireless channels employing coded MIMO systems to achieve both spatial diversity and coding gains has not been explicitly explored. To this end we propose, in this paper, to evaluate the error performance of Multiple-Input Multiple-Output (MIMO) systems employing Orthogonal Space-Time Block Codes (OSTBC) and Hierarchical 4/MQAM Modulation to promote unequal error protection of the coded data. The approach adopted provides excellent unequal error protection capabilities through the hierarchically modulated symbol and both diversity as well as coding gains are achieved. The proposed MIMO systems are designed and implemented in MATLAB Simulink® 2017 and error performances are evaluated through simulations. Experimental results show at a Bit Error Probability (BEP) of 10−4 a coding gain of around 10 dB can be observed between the base and refinement sub-channels with the 2x2 Alamouti code.

Quasi Orthogonal Space Time Block Code Over Nakagami-m Frequency Selective Fading Channels with Simple Decoding Complexity

In this paper, a Quasi Orthogonal Space Time Coding (QOSTBC) system over Nakagami-m frequency selective fading channels is introduced. The proposed scheme is carried out for the M-QAM modulation schemes assuming imperfect channel state information at the receiver. Inter symbol interference effect introduced due to the assumption of the frequency selective fading channels is eliminated by using the Orthogonal Frequency Division Multiplexing (OFDM) technology. Through the Bit Error Rate (BER) versus Signal to Noise Ratio (SNR) simulation results under different values of both Nakagami-m parameter and channel estimation error, the validity of the proposed technique is demonstrated. The results confirm that the BER in the case of frequency selective fading is overlapped with that of flat fading. This implies that the use of OFDM technology mitigates the effect of Inter-Symbol Interference (ISI) caused by frequency selectivity in the channel. Also, the results show that as the imperfect channel estimation error increases the performance degrades.

Implementation of an Adaptive MIMO System using Effective Minimization of Frame Error Rate

Paper Multiple Input Multiple Output (MIMO) is a technique which is now being widely used for wireless communication techniques such as 4G LTE. MIMO uses multiple antennas at the transmitter as well as at the receiver side in order to improve spectral efficiency although it increases the system complexity. Multipath propagation, which is the drawback for wireless communication, is used as an advantage in MIMO. This paper presents a model of Adaptive MIMO system in Simulink. The system adapts to specific transmit and receive diversity depending on the frame error rate. The proposed system uses 4 transmitting and receiving antennas, the number of antennas change as per the adaptation algorithm. The data is sent in the form of frames with each frame carrying the desired number of bits. Here, we have implemented the Orthogonal Space-Time Block Coding (OSTBC) scheme in a MATLAB Simulink model and implemented an adaptive algorithm to change the quantity of transmitting and receiving antennas depending on the frame error rate (FER) value.

Full diversity space time block codes with improved power distribution characteristics

In this paper, we introduce a technique for improving power distribution characteristics of space time block codes (STBCs) which include peak to average power ratio (PAPR), average to minimum power ratio (Ave/min), and probability of transmitting “zero” by antenna. We consider STBCs in multiple input multiple output (MIMO) and multiple input single output (MISO) systems that achieve full diversity for linear or maximum likelihood (ML) receivers. It is proved that by multiplying a specific non-singular square matrix by the code matrix, a new code is obtained that achieves full diversity and the power distribution characteristics are improved. The proposed technique is general can be applied to any type of full diversity STBCs such as Toeplitz codes, orthogonal STBCs (OSTBCs), overlapped Alamouti codes (OACs), group orthogonal Toeplitz codes (GOTCs), and embedded Alamouti codes (EACs), and can ease their practical implementation. We systematically present closed-form expressions for the matrices multiplied by Toeplitz codes, OACs, and EACs. Because of the existence of these codes for any number of antennas, the closed-form can be used in 5G which needs huge number of antennas. The performance of the proposed technique is evaluated in terms of bit error rate (BER) and power distribution characteristics. The introduced method provides a trade-off between PAPR, Ave/min, probability of transmitting zero, and BER, to cope with the practical requirements. We also investigate the effect of the proposed method on the PAPR of output signal of shaping filter which is referred to as analog domain PAPR. The results indicate the efficiency of the introduced technique. The proposed method can balance the tradeoff between PAPR, spectral efficiency, and BER.

Analysis and Demonstration of Quasi Trace Orthogonal Space Time Block Coding for Visible Light Communications

In the VLC context, pulse position modulation (PPM) and similar modulations are typically used when the overall complexity of the transmitter is required to be low or the system needs to support dimming, i.e., dynamically control the illumination level of the transmitter. However, despite the power efficiency of PPM, it is known to be bandwidth inefficient. Having known the trade-off between reliability and spectral efficiency, in this paper we propose a PPM-based space-time block coding (STBC) technique named as quasi-trace-orthogonal (QTO), derived from trace-orthogonal, to increase the spectral efficiency of PPM VLC’s by limiting the reliability loss. We provide Monte-Carlo simulations for a $4\times 4$ MIMO-VLC system and validate the results experimentally, and show that for a given signal-to-noise-ratio, the QTO-STBC based 4-PPM VLC system offers higher spectral efficiency at a cost of higher symbol error rate compared to trace-orthogonal STBC.

Physical Layer Security for Multiple-Input Multiple-Output Systems by Alternating Orthogonal Space-Time Block Codes

Algorithms are provided to build a large set of unique complex-valued orthogonal space-time block codes (STBCs) from a known or standard STBC. A physical layer security (PLS) scheme is proposed to take advantage of this set by alternating the STBC in use over a multiple-input single-output (MISO) or multiple-input multiple-output (MIMO) communications link between base station (BS) and user equipment (UE). A practical procedure is proposed and demonstrated to build individual STBCs from the set without use of a lookup table. The sufficient statistic is given and proven to allow for maximal ratio combining (MRC) by the intended receiver for all STBCs in the set. An algorithm is offered for the UE to update the MRC matrix in use as the STBC alternates. Definitions are provided for cryptograms, key residues (KRs), key residue classes (KRCs), and message and cryptogram residue classes pertaining to STBC PLS schemes. These definitions are used to present analysis of the information-theoretic security of the proposed PLS scheme to include message and key equivocation. Theoretical expected bit error rate (BER) for a passive eavesdropper is proven and plotted along with Monte Carlo simulations for confirmation. Discussion of different attack models is provided. Cost and attack complexity are compared between the proposed scheme and two related techniques from the literature.