Space-time Block Codes Research Articles

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 enhancement of cooperative networks utilizing MAP decoder and Alamouti code

Abstract In this paper, we introduced another methodology for the cooperative network using the maximum posterior (MAP) and the Alamouti code decoding scheme for the multiple-input single-output (MISO) wireless networks that use decode and forward (DF) protocol as a cooperation protocol. Without loss of generality, the considered network consists of one source, one relay and one receiver. A closed-form expression for the upper bound of the bit error probability is derived. The obtained upper bound expression can be utilized in the power optimization problems, relay positioning issue. The results that are shown in this paper clear that the proposed scheme has two advantages over the related work. The first advantage is that it has less complexity. The second one is that it has better spectrum efficiency by using less number of channels. Therefore, our contribution can be summarized in improving the spectrum efficiency and reducing the complexity of the cooperative network, but the paid price is that the bit error rate increases by a little ratio.

Pilot Symbol Error Re - Orthogonalization in 2 × 2 MIMO Systems of Wireless Communication

Abstract A 2×2 MIMO wireless communication system with channel estimation is simulated, in which two transmit, and two receive antennas are employed. The orthogonal pilot signal approach is used for the channel estimation, where the Hadamard sequences are used for piloting. Data are modulated by coherent binary phase-shift keying, whereupon an orthogonal space-time block coding subsystem encodes information symbols by using the Alamouti code. Based on the simulation, it is ascertained a possibility to decrease the bit-error rate by substituting the Hadamard sequences for the sequences having irregular structures, and constituting the eight known orthogonal bases. Considering a de-orthogonalization caused by two any pilot sequence symbol errors, the bit-error rate is decreased by almost 2.9 %. If de-orthogonalizations are caused by two repeated indefinite, and definite pilot sequence symbol errors, the decrements are almost 16 % and 10 %, respectively. Whichever sequences are used for piloting, the 2×2 MIMO system is ascertained to be resistant to the de-orthogonalization if the frame is of 128 to 256 symbols piloted with 32 to 64 symbols, respectively.

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.

Golden Coded GFDM for 5G Communication

The 5th Generation (5G) of wireless communication will be heterogeneous to support various traffic types and applications. Generalized Frequency Division Multiplexing (GFDM) is a 5G non-orthogonal waveform contender that offers scalable and spectrally compliant air interface which addresses the needs of 5G requirements. To aid the demand of high-capacity and reliable transmission, multiple antenna techniques are relied upon. In this work, the 5G modulation scheme GFDM is combined with a full rate Space–Time Block Code (STBC) with nonvanishing determinant called Golden Codes to exploit the diversity to the fullest. The proposed work is implemented in a real-time SDR test-bed called Wireless Open Access Research Platform (WARP). The proposed work is compared with 4G OFDM modulation in both Golden Coded and Uncoded case. The performance is assessed in terms of BER and Capacity/Bandwidth resolution. From the investigations, it is seen that the BER performance of Golden Coded GFDM outperforms the Uncoded GFDM by 3 dB SNR gain and attains a near-equal performance as OFDM. Also, it is evident from the analysis that, there is a 3.5 bps/Hz gain in capacity when compared to OFDM.

Performance analysis of mixed MISO RF/SIMO FSO relaying systems

This paper investigates the end-to-end performance of a dual-hop mixed multiple-input single-output (MISO) radio-frequency (RF)/ single-input multiple-output (SIMO) free-space optical (FSO) relaying system. The Rayleigh distribution and the Gamma-Gamma (ΓΓ) distribution are adopted to describe the RF link and the turbulence effects of the FSO link, respectively. We consider Alamouti-type space-time block coding (A-STBC) and transmitter antenna selection (TAS) schemes from the source to the relay. There are amplify-and-forward (AF) with fixed gain and variable gain protocols for the relay. The closed-form expressions of the outage probability, outage capacity, average symbol error rate (SER) and channel capacity are derived in this paper. We discuss the end-to-end performance of different coding and relay schemes under different turbulence conditions.

MmWave Lens-Based MIMO System for Suppressing Small-Scale Fading and Shadowing

In this paper, we propose a generalized millimeter-Wave (mmWave) reconfigurable antenna multiple-input multiple-output (RA-MIMO) architecture that takes advantage of lens antennas. The considered antennas can generate multiple independent beams simultaneously using a single RF chain. This property, together with RA-MIMO, is used to combat small-scale fading and shadowing in mmWave bands. To this end, first, we derive a channel matrix for RA-MIMO. Then, we use rate-one space-time block codes (STBCs), together with phase-shifters at the receive reconfigurable antennas, to suppress the effect of small-scale fading. We consider two kinds of phase shifters: i) ideal which is error-free and ii) digital which adds quantization error. The goal of phase-shifters is to convert a complex-valued channel matrix into real-valued. Hence, it is possible to use rate-one STBCs for any dimension of RA-MIMO. We investigate diversity gain and derive an upper bound for symbol error rate in cases of ideal and digital phase-shifters. We show that RA-MIMO achieves the full-diversity gain with ideal phase-shifters and the full-diversity gain for digital phase-shifters when the number of quantization bits is higher than one. We investigate RA-MIMO in the presence of shadowing. Our analysis demonstrates that, by increasing the dimension of RA-MIMO, the outage probability decreases which means the effect of shadowing decreases. Numerical results verify our theoretical derivations.

스위치와 180° 하이브리드를 이용한 단일 송신기 송신 다이버시티

Generally, two synchronized transmitters are required to implement transmit diversity, such as Alamouti codes. However, because two transmitters are used, many disadvantages arise, such as increased price, power consumption, complexity, and the necessity of synchronization and calibration. In this paper, we proposed a new method to realize transmit diversity only using one transmitter. The proposed method combines baseband signal processing and an RF circuit, which connects a 180° hybrid and one switch between one transmitter and two transmit antennas, and controls the switch at the mid-point of the transmission bit. Because the proposed system has only one transmitter, the power consumption and hardware cost can be reduced by half, and the diversity gain can be realized in a fading environment. We verified the feasibility of the proposed method by computer simulations and confirmed that diversity operation can be realized using hardware.

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.

The effective capacity of two-unicast network coding STBC under retransmission schemes

Downlink multiuser network coding (NC) automatic repeat request (ARQ) systems can provide significant throughput improvements over basic ARQ systems. In this paper, we consider the case of two-unicast flows and analyze their performance in terms of the effective capacity (EC) under retransmission schemes. We extend the derived EC of NC-ARQ for asymmetric channels where users have different data rates. For NC-ARQ, two scenarios at the source are considered to handle the transmission. The EC expression for two-unicast flows using Alamouti space time block coding (STBC) is also derived. We also present a new scheme that combines both NC and STBC and, denoted by NC-STBC-ARQ. Our results show that the new NC-STBC-ARQ improves the EC over basic STBC in the low-to-moderate signal-to-noise ratio (SNR) regime. Besides, the new NC-STBC-ARQ improves the EC compared to basic NC-ARQ for a moderate-to-high SNR regime.

Robust decoding strategy of MIMO-STBC using one source Kurtosis based GPSO algorithm

Most research papers have referred that the performance of bit error rate (BER) for a Multiple-Input Multipl-Output Space–Time Block Code (MIMO-STBC) decoder fundamentally relies on the number of pilot symbols. This paper proposes a new strategy for decoding a MIMO-STBC using blind source separation (BSS). First, the STBC decoder is modeled as a noisy linear mixing system, which is decomposed using the technique of real-imaginary (Re-Im). Then Kurtosis based BSS algorithm is applied to the decomposition model. The method of one source extraction is also used to reduce decoding time efficiently. Finally, a global particle swarm optimization method (GPSO) is combined with the one source extraction Kurtosis based BSS to obtain a high speed/low complexity MIMO-STBC decoder. The classical PSO algorithm in this paper is modified by innovating a new updating formula, which is the combination of the swarm behavior and BSS algorithm. Although the new decoder is more complicated as compared with the conventional one, it provides superior BER performance using a fewer number of pilot symbols. Computer simulation for QPSK STBC in a quasi-static flat fading MIMO channel was implemented using MATLAB2018. The new decoder algorithm was tested using only two receivers, worst case. The important point denoted through simulation is the BER performance of the proposed decoder was significantly got better when the length of frames gets longer. The proposed strategy was also used in decoding the $$8\times 8$$ MIMO-STBC system in an extreme noise environment. It was found the BER performance improved nine times as compared with the traditional decoder. Finally, the modified GPSO algorithm made the proposed decoder needs a very small number of iterations, even though the search space dimension is very high.

Modulation and RS-CC rate specifications in WiMAX IEEE 802.16 Standard with MATLAB Simulink model

The intensive use of broadband system leading to focusing of telecommunication development industries, which are characterized by high quality features. Forthisissue, high transmission abilities in a new technologies systems have been designed. the WiMAX concept were proposed where a wireless transmission infrastructure that allows a fast deployment as well as low maintenance costs. Based on the IEEE 802.16-2004 standard, in this paper an end-to-end baseband model of the physical layer of a wireless metropolitan area network (WMAN) have been implemented using MATALB Simulink, according to the IEEE® 802.16-2004 standard. Supporting all of the mandatory coding and modulation options. It also illustrates Space-Time Block Coding (STBC), an optional transmit diversity scheme specified for use on the downlink. it illustrates the use of digital pre-distortion, a technique for extending the linear range of a nonlinear amplifier. Also modulation sets have been changed and tested in the model to reduce running time and power consumption. Finally, measurements of Error vector magnitude EVM and modulation error ratio MER were performed.

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).

Improved DOA estimation method by distinction of different transmit signals in automotive MIMO frequency‐modulated continuous wave radar systems

This study proposes an advanced direction-of-arrival (DOA) estimation method for automotive multiple-input multiple-output (MIMO) fast-ramp radar systems. To distinguish the transmitted signal at the receiving antenna, the orthogonal code can be applied to each transmitted signal. In this case, to correctly estimate the angles of the targets, the authors also have to match the distinguished signals to each transmit antenna element. In this study, they use the space-time block code to distinguish the transmitted signals from the receiving antennas. Furthermore, by applying the deterministic maximum likelihood algorithm to each of the distinguished signals, they can find the true antenna array for DOA estimation and achieve higher estimation accuracy than false antenna array cases. Furthermore, the maximum detectable velocity is doubled compared to the conventional decoding method. In the simulation results, the proposed method provides a three degree smaller root-mean-squared error compared to the case when it is not applied. The proposed method also estimates the DOAs of the targets well at low signal-to-noise ratios. In addition, the effectiveness of the proposed method was verified by measurement results.

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.

Performance improvement of space diversity technique using space time block coding for time varying channels in wireless environment

Performance improvement of space diversity technique using space time block coding for time varying channels in wireless environment

Low computational complexity methods for decoding of STBC in the uplink of a massive MIMO system

Reducing the computational complexity of the modern wireless communication systems such as massive MIMO configurations is of utmost interest. In this paper, we propose algorithms which can be used to accelerate matrix inversion and reduce the complexity of common spatial multiplexing schemes in massive MIMO systems. Here, we specifically investigate the performance of the proposed methods in systems that utilize STBC (Space-Time Block Code) in the uplink of dynamic massive MIMO systems for different scenarios. A multi-user system in which the base station is equipped with a large number of antennas and each user has two antennas is considered. In addition, users can enter or exit the system dynamically. For a given space-time block coding/decoding scheme, the computational complexity of the receiver will be significantly reduced by employing the proposed methods. The first approach is utilizing Neumann series to approximate the inverse matrix for linear decoders. The second tactic is reducing the computational complexity of the STBC decoders when a user is added to system or removed from it. In the proposed schemes, the matrix inversion for ZF and MMSE decoding is derived from inversing a partitioned matrix and Woodbury matrix identity. Furthermore, the suggested techniques can be utilized when the number of users is fixed but the CSI changes for a particular user. The mathematical equations for both approaches are derived and the complexity of the suggested methods is compared to the direct computation of the inverse matrix. Moreover, the performance of the proposed algorithms is evaluated in terms of the system BER (bit error rate). Evaluations confirm the effectiveness of the proposed approaches.

A method for improving power distribution characteristics of space time block codes

Improving power distribution characteristics of space time block codes (STBCs), namely peak to average power ratio (PAPR), average to minimum power ratio (Ave/min), and probability of transmitting "zero" by antenna, makes easier their practical implementation. To this end, this study proposes to multiply full diversity STBC with a non-singular matrix in multiple input multiple output (MIMO) or multiple input single output (MISO) systems with linear or maximum likelihood (ML) receivers. It is proved that the obtained code achieves full diversity and the order of detection complexity does not change. The proposed method is applied to different types of STBCs. The bit error rate (BER) and power distribution characteristics of the new codes demonstrate the superiority of the introduced method. Further, lower and upper bounds on the BER of the obtained STBCs are derived for all receivers. The proposed method provides trade-off among PAPR, spectral efficiency, energy efficiency, and BER.