Shift Keying Modulation Scheme Research Articles

A novel carrier index M‐ary differential chaos shift keying modulation scheme

AbstractTo obtain better spectral efficiency and higher bit rate, a novel carrier index M‐ary differential chaos shift keying modulation scheme is proposed. In this system, part of subcarriers is assigned to the chaotic reference so that it can carry extra data bits through carrier index modulation, while one of the remaining subcarriers is activated to transmit the data‐bearing signal. In addition, M‐ary DCSK modulation is also applied to data‐bearing signals based on the constellation theory and Walsh codes. Theoretical bit error rate expressions are derived over the multipath Rayleigh fading and additive white Gaussian noise channels. Simulations and comparisons are performed with various combinations of chaotic sequence lengths, subcarrier numbers and constellation sizes. Results show that the proposed scheme can outperform other counterparts in both spectral efficiency and bit error rate performances.

Fully Breaking Entanglement of Multiple Harmonics for Space- and Frequency-Division Multiplexing Wireless Applications via Space-Time-Coding Metasurface.

Harmonic generation and utilization are significant topics in nonlinear science. Although the progress in the microwave region has been expedited by the development of time-modulated metasurfaces, one major issue of these devices is the strong entanglement of multiple harmonics, leading to criticism of their use in frequency-division multiplexing (FDM) applications. Previous studies have attempted to overcome this limitation, but they suffer from designing complexity or insufficient controlling capability. Here a new space-time-coding metasurface (STCM) is proposed to independently and precisely synthesize not only the phases but also the amplitudes of various harmonics. This promising feature is successfully demonstrated in wireless space- and frequency-division multiplexing experiments, where modulated and unmodulated signals are simultaneously transmitted via different harmonics using a shared STCM. To illustrate the advantages, binary frequency shift keying (BFSK) and quadrature phase shift keying (QPSK) modulation schemes are respectively implemented. Behind the intriguing functionality, the mechanism of the space-time coding strategy and the analytical designing method are elaborated, which are validated numerically and experimentally. It is believed that the achievements can potentially propel the time-vary metasurfaces in the next-generation wireless applications.

Comparative Performance of Point-to-Point Multiple Input Multiple Output System under Weibull and Rayleigh Fading Channels

Multiple-input multiple-output (MIMO) technologies use multiple antennas at the sender and the receiver to get the high data rate that the next-generation communication system needs. This paper compares MIMO systems using the Quadrature Phase Shift Keying (QPSK) modulation scheme for two-channel distributions of Rayleigh and Weibull types. The performance of the work is far with the Minimum Mean Square Equalizer (MMSE) in terms of Bit Error Rate (BER) for various antenna number situations on the transmitter and receiver sides. The MIMO module is carried out using MATLAB code. The channel noise will be a signal of random noise that is generated. To mitigate the impact of inter-channel interference, the MMSE approach employs inverse filtering at the receiver, and BER will be calculated. According to simulation results, the system's performance is primarily influenced by the number of antennas; it decreased as the number of antennas increased, and the BER of the Weibull channel decreased as the two-parameter value increased

Wirelessly Powered and Bi-Directional Data Communication System With Adaptive Conversion Chain for Multisite Biomedical Implants Over Single Inductive Link.

A wirelessly powered and data communication system is presented which is implemented as a full system, designed for multisite implanted biomedical applications. The system is capable of receiving wireless power and data communication for each implant separately, using inductive links with different resonance frequencies. To achieve this, dual-band coils are presented in the system. In addition, the system supports bi-directional half-duplex data communication, utilizing amplitude and load shift keying (ASK and LSK) modulation schemes over a single inductive link. The system employs a digitally assisted active rectifier and an automatic resonance tuning system, to improve the power transfer efficiency (PTE) through various coupling coefficients, while minimizing the reverse current and power dissipation. The power control unit enables closed-loop monitoring to prevent high or low power delivery, and it can detect inefficient or excessive wireless power transmission or prevent temperature elevation by limiting the voltage to a safe level. A new structure of self-sampling separated- Vb ASK demodulator is proposed in the paper which is utilized within the data conversion chain, serving both the external and implanted units. The whole system is fabricated using a standard 180-nm 1.8/3.3 V CMOS process with a core area of 0.82 mm[Formula: see text]. The system is tested with coupled multisite inductive links and offers the maximum overall PTE of 31.2%, from the Tx coil to the implant load.

Smart Energy Borrowing and Relaying in Wireless-Powered Networks: A Deep Reinforcement Learning Approach

Wireless energy harvesting (EH) communication has long been considered a sustainable networking solution. However, it has been limited in efficiency, which has been a major obstacle. Recently, strategies such as energy relaying and borrowing have been explored to overcome these difficulties and provide long-range wireless sensor connectivity. In this article, we examine the reliability of a wireless-powered communication network by maximizing the net bit rate. To accomplish our goal, we focus on enhancing the performance of hybrid access points and information sources by optimizing their transmit power. Additionally, we aim to maximize the use of harvested energy, by using energy-harvesting relays for both information transmission and energy relaying. However, this optimization problem is complex, as it involves non-convex variables and requires combinatorial relay selection indicator optimization for decode and forward (DF) relaying. To simplify this problem, we utilize the Markov decision process and deep reinforcement learning framework based on the deep deterministic policy gradient algorithm. This approach enables us to tackle this non-tractable problem, which conventional convex optimization techniques would have difficulty solving in complex problem environments. The proposed algorithm significantly improved the end-to-end net bit rate of the smart energy borrowing and relaying EH system by 13.22%, 27.57%, and 14.12% compared to the benchmark algorithm based on borrowing energy with an adaptive reward for Quadrature Phase Shift Keying, 8-PSK, and 16-Quadrature amplitude modulation schemes, respectively.

Design of Chaotic-Based PPM-PI-DCSK Modulation for Wireless Communications

In this letter, a joint pulse position modulation (PPM) and permutation index differential chaos shift keying (PI-DCSK) modulation scheme (PPM-PI-DCSK) is proposed to increase the data rate and improve performance. In PPM-PI-DCSK, the bit stream is divided into blocks of mp+mc+1 bits, where mp bits are modulated by PPM, mc bits are modulated by PI modulation, and the last one bit is modulated by DCSK. The theoretical bit error rate (BER) performance of the proposed PPM-PI-DCSK is derived over multipath Rayleigh fading channels and validated via simulations. Simulation results show that the proposed PPM-PI-DCSK outperforms the benchmark DCSK-based schemes. Furthermore, the performance superiority is also demonstrated by the frequency-modulated PPM-PI-DCSK over a typical ultra-wideband (UWB) channel. This demonstrates the superiority and feasibility of the proposed scheme in practical applications.

Performance evaluation of re-configurable intelligent surface-assisted underwater and free-space wireless optical communication in the skip-zones

Note that 40% of the world’s population, i.e., three billion people, live within 100 km of the ocean or seashore surfaces. To explore and experience marine life, human activities in ocean-based environments are increasing day-by-day. To make human activities safer and stronger, highly efficient and reliable wireless communication is crucial for conveying any unnatural things that occur in oceans. Exploring the vast environment is difficult because of its rapidly changing characteristics, which creates various levels of skip-zone, resulting in the loss of information. A re-configurable intelligent surface (RIS)-assisted optical link is employed to mitigate the effects of skip-zones and enable high-speed and efficient communication links. In addition to this, it is also necessary to convey information to the coastal line through a RIS-assisted free-space optical (FSO) link. In this study, we propose a RIS-assisted dual-hop underwater wireless optical communication (UWOC)-FSO communication system. For the proposed RIS-based dual-hop UWOC-FSO system, closed-form expressions for the outage probability (OP), bit error rate (BER) for coherent and non-coherent type binary phase-shift keying, binary frequency shift keying modulation schemes are derived and results are corroborated with the Monte-Carlo simulations and asymptotic analysis.

An enhanced 2-D color space diversity using RGB-LED overlapping for optical camera communication

In this paper, an enhanced two-dimension (2-D) color space diversity technique using red, green, and blue light emitting diode (RGB LED) overlapping is proposed and investigated experimentally to improve the system reliability for optical camera communication (OCC). The transmitter adopts an 8-color shift keying (8-CSK) modulation scheme with two RGB LED overlapping. The receiver uses a camera to form a multi-input single-output system to improve capacity. Different mapping methods are proposed and compared in 2-D YCbCr and CIElab color space to avoid the influence of brightness in conventional 3-D RGB space. Besides, clustering-based demapping is applied in the OCC system to transfer the color information into a data stream. The experimental results show that the mapping scheme with the maximum Euclidean distance in 2-D YCbCr color space has the best bit error rate (BER) performance. Compared with the conventional 3-D RGB color space, the proposed enhanced 2-D YCbCr color space diversity has a higher resolution to signal, which can realize 1.46 dB Q-factor improvement at an illumination of 660 lux. In addition, it can achieve a net data rate of 11.52 kb/s and maintain a 7% forward error correction (FEC) requirement even under low illumination. It is verified that the proposed scheme is a potential application for capacity and performance improvement.

Ultrasonic Energy and Data Transfer through a Metal—Liquid Multi-Layer Channel Enhanced by Automatic Gain and Carrier Control

Ultrasonic communication and power transfer are attractive solutions when conventional electromagnetic-based or wired connections are unfeasible. Most ultrasonic communication applications concern a single-solid barrier. Nevertheless, some relevant scenarios can be composed of several fluid—solid media, through which communication and power transfer are intended. Due to its multi-layer nature, insertion loss and, consequently, the system efficiency considerably decrease. This paper presents an ultrasonic system capable of simultaneously power transferring and transmitting data through a set of two flat steel plates separated by a fluid layer using a pair of co-axially aligned piezoelectric transducers on opposite sides of the barrier. The system is based on frequency modulation and adopts a novel technique for automatic gain and automatic carrier control. The modems used herein were developed specifically for this application, rendering the system able to transfer data at a rate of 19,200 bps, using the frequency shift keying (FSK) modulation scheme and simultaneously transferring 66 mW of power through two flat steel plates (5 mm) separated by a fluid layer (100 mm), which completely supplied a pressure and temperature sensor. The proposed automatic gain control allowed a higher data transmission rate and the automatic carrier control reduced power consumption. The former reduced the transmission error from 12% to 5%, while the latter reduced the global power consumption from 2.6 W to 1.2 W. The proposed system is promising for monitoring applications such as oil wellbore structural health monitoring systems.

A Novel Coupled Code Shifted M-ary Differential Chaos Shift Keying Modulation

In this paper, a novel coupled code shifted M-ary differential chaos shift keying modulation scheme is proposed as a simple and low-cost solution to reference removal. In this scheme, only two information-bearing signals are transmitted. Both signals are modulated by selected Walsh code sequences with specific indices determined by the index bits, and one of them also carries an additional M-ary information symbol. Since these two information-bearing signals are coupled by the same chaotic message bearer, data bits can be easily recovered according to the correlation between these two signals so that the transmission of reference signals can be completely avoided. Theoretical Bit Error Rate (BER) expressions are derived over the additive white Gaussian noise and multipath Rayleigh fading channels. Furthermore, simulations and comparisons indicate that the proposed system can achieve better BER performance with lower complexity.

Analysis of Bit Error Rate in Binary Phase Shift Keying Modulation Scheme Using Matlab

Analysis of Bit Error Rate in Binary Phase Shift Keying Modulation Scheme Using Matlab

Performance Analysis of Wireless Adhoc Networks in Flat Fading and Frequency Selective Fading channels

This research article presents the probability of error analysis in flat fading and frequency selective fading channels for wireless adhoc networks which can aid mobile sustainable networks. Adhoc networks due to their network arrangement which is not fixed and can exhibit mobility its physical layer analysis metric of probability of error needs to be analysed. Information data transmitted from a source node into a wireless channel due to its multipath propagation can limit the performance determined by the metric of probability of error. Wireless channel experiencing flat fading can have Rayleigh distribution, Rician distribution and frequency selective fading channel can be obtained from the power delay profile (PDP). Simulation results are obtained for wireless adhoc networks in matrix laboratory (MATLAB) using binary phase shift keying (BPSK) modulation scheme in flat fading channel and frequency selective fading channels for assessing wireless adhoc networks which also can exhibit similar conditions in mobile networks. The obtained simulation results can provide significant information where 5G and 6G networks are to be deployed and can aid real time implementation.

Noncoherent space-time coding for correlated massive MIMO channel with Riemannian distance

This paper considers a massive multiple-input multiple-output (MIMO) uplink system in correlated Rayleigh fading channels. A transmitter with two antennas needs to send data timely to a base station with a large number of antennas. We assume the channel coefficients keep constant during two consecutive time slots and change independently in the following two successive time slots. We construct a Riemannian-distance (RD) based noncoherent detector for such a system. Also, we propose a novel noncoherent parametric space-time coding method. We first attain the closed-form solutions of the optimal sub-constellation structures for fixed modulation orders with the max-min rule. Then, we determine the optimal modulation order for each sub-constellation. The analytical results show that our proposed scheme can attain a larger RD distance than the existing massive uniquely factorable constellation coding (MUFC) scheme. Further, we illustrate that our proposed coding scheme enables a low-complexity RD decoding algorithm. Simulation results show that our proposed scheme performs better than the current phase shift keying modulation scheme and MUFC scheme.

Enhanced Modulation for Multiuser Molecular Communication in Internet of Nano Things

The novel concept of Internet of Nano Things (IoNT) brings even larger groups of nanomachines collaborating to achieve more complex tasks in the military, medical, and security fields. Moreover, Internet of Bio-Nano Things (IoBNT) is an emerging technology defining the seamless connection of nanomachines and biological entities with each other where they can access the traditional wireless communication networks to provide novel Internet of Things (IoT) applications, such as health monitoring, healthcare, and targeted therapy. The exchange of information between biological cells is based on the synthesis, transformation, emission, propagation, and reception of molecules. This information exchange is recently classified in telecommunications as molecular communication which is a biologically inspired technique to communicate in very small dimension networks. In nanonetworks, a high number of nanothings will operate in the same medium and they interfere with each other. Multiuser interference will create significant limits. Hence, we introduce to use the direction of releasing molecules as a new property to convey information. Releasing the molecules to the specific directions enhances the performance of molecular communication systems due to multiusers interference mitigation. Hence, adjacent transmitters can convey information in different directions, simultaneously. Then, we propose the binary direction shift keying (BDSK) modulation scheme where the transmitter pumps molecules in two different directions. Next, we obtain the error probability and achievable bit rate of BDSK modulation. Finally, we evaluate the performance of BDSK modulation by numerical results. The result of this article can be useful for molecular communication relay systems where relay nodes convey information to the different destinations.

Multi-User Successive-Coded Spatial Modulation Scheme Based on Beamforming

By combining an existing successive-coded spatial shift keying (SC-SSK) modulation scheme with a modulation scheme that uses the traditional constellation, we propose a new successive coded spatial modulation (SC-SM) scheme. This scheme uses spatial domain and constellation domain to jointly transmit information bits, which increases the achievable rate of the system. In order to extend the SC-SM scheme to multi-user scenario, a multi-user SC-SM (MU-SC-SM) scheme based on beamforming is proposed. The proposed MU-SC-SM scheme not only eliminates the inter-user interference (IUI) and enhances the received signal-to-noise ratio (SNR) of the served user, but also resolves the conflict between beamforming and spatial modulation. The achievable rate, the bit-error-rate (BER) performance and computational complexity of the proposed MU-SC-SM scheme are analyzed in detail. The impacts of the imperfect channel state information on the BER performance are also analyzed. Simulations are carried out to verify that the proposed MU-SC-SM scheme is superior to existing multi-user spatial modulation schemes in BER performance.

A Novel Multi-User Carrier Index Differential Chaos Shift Keying Modulation Scheme

In this paper, a novel multi-user carrier index differential chaos shift keying (MU CI-DCSK) modulation scheme is proposed. For a better utilization of spectrum resources, each user is allocated a private subcarrier for reference signal transmission, while the remaining subcarriers are public and shared by all users to transmit their own data-bearing signals. To avoid user interferences in this design, users are distinguished in a code division multiple access (CDMA) way based on Walsh codes. By exploiting the redundancies in the transmitted signals, repeated segments of received signals are averaged, leading to greatly reduced noises and a noticeable improvement in bit error rate (BER) performance. BER expressions of this new system are derived over the additive white Gaussian noise (AWGN) and multi-path Rayleigh fading channels. Simulation results and comparisons are performed to verify the feasibility and advantages of this new scheme.

Mode division multiplexing free space optics system with 3D hybrid modulation under dust and fog

Mode division multiplexing (MDM) is an emerging information transmission technique in which multiple data signals can be transmitted simultaneously on different modes of a single wavelength laser beam over a free-space channel. MDM is a potential technique for the realization of high-speed spectral efficient communication links for future generations of wireless networks. We present a novel MDM-based free-space optics (FSO) system. The system integrates a 3D hybrid modulation scheme produced by combining carrier suppressed-non-return-to-zero (CSNRZ), differential quadrature phase-shift keying (DQPSK), and polarization shift keying (PolSK) modulation schemes for beyond 100 Gbps applications. Three unrelated 40 Gbps data signals are modulated and transmitted on one optical carrier utilizing three distinct signal properties: amplitude (CSNRZ), phase (DQPSK), and polarization state (PolSK). The proposed 3D modulation scheme offers a high-capacity system, where each channel transmits 4 Gbps as compared to 1 Gbps in the case of OOK modulation. MDM using distinct Hermite Gaussian modes: (HG00 and HG01) of a laser beam is incorporated to boost the spectral efficiency and information rates of the FSO link. The proposed 120 Gbps single-channel MDM-FSO link performance is examined under the impact of different levels of dust and fog environmental conditions using quality factors and received eye diagrams as the performance metrics. This system achieved optimal performances up to 1250 m (very light dust), 540 m (light dust), 170 m (moderate dust), 750 m (low fog), and 425 m (medium fog). In the worst-case scenario, the system manages to work up to a 67 m range in dense dust with a maximum attenuation of 297.38 dB/km and a 200 m distance in heavy fog with only 90 dB/km attenuation which is less than 1/3rd of the attenuation measured for dense dust event. In addition, our results and the case studies confirm that dust introduces greater signal attenuation than fog. Therefore, an encounter with a dust environment should be considered as the bottleneck issue for FSO links. The creative contribution of this paper is to put forward a bandwidth-efficient MDM-FSO-enabled B5G system that could be deployed in harsh and challenging locations at reduced visibility. This is expected to be further technically sustainable owing to the use of advanced 3D hybrid optical orthogonal modulation and therefore find use in implementing 5G and 6G cellular and data networks.

Evaluation of Reconfigurable Intelligent Surface-Assisted Underwater Wireless Optical Communication System

Reconfigurable intelligent surfaces (RISs) are an emerging technology aimed to enhance the energy and spectrum efficiency of wireless communication links by reconfiguring the propagation environment of radio-frequency (RF)/optical waves. Planar phased meta-material surfaces or reflect-arrays for RF RIS and multiple smart mirrors have been used for activating optical RIS. In this article, we analyze the underwater optical wireless communication (UWOC) system performance in terms of bit error rate (BER), outage probability (OP) and channel capacity (CC) under the influence of underwater turbulence, beam attenuation, pointing errors and occlusion or blockage due to obstacles. A RIS-assisted UWOC proposed to mitigate the effects obstacles, pointing errors and turbulence and improve the system performances. The probability density function and cumulative distribution functions of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$N$</tex-math></inline-formula> RIS elements based UWOC system are evaluated over the underwater turbulence, pointing errors and blockage due to obstacles. The novel closed-form expressions for BER under binary phase shift keying and binary frequency shift keying modulation schemes using with and without coherent detection, OP, and CC for intensity modulation-direct detection and heterodyne detection cases are obtained and plotted according to the number of RIS elements with respect to the average signal-to-noise ratio. The numerical BER results are validated with the Monte-Carlo simulations.

Double-Stream Differential Chaos Shift Keying Communications Exploiting Chaotic Shape Forming Filter and Sequence Mapping

A new Differential Chaos Shift Keying modulation scheme exploiting Chaotic Shape-forming Filter and Sequence Mapping (CSF-SM-DCSK) is being proposed. The new CSF-SM-DCSK system employs a novel sequence mapping rule and includes a data correction module to achieve a good trade-off between the low Bit Error Rate (BER) performance and high transmission rate. It transmits two data streams simultaneously and preserves the simplicity and robustness of DCSK method. Channel one, transmitting a Low Priority Stream (LPS), generates the chaotic carrier by a Chaotic Shape-forming Filter (CSF) at the transmitter and applies a coherent Matched Filter (MF) at the receiver to recover the information. Channel two, transmitting a High Priority Stream (HPS), relies on conventional DCSK modulation, while the reference and information-bearing parts are transmitted simultaneously with orthogonal sine and cosine carriers. This double-stream solution eliminates the need for analog RF delay lines and doubles the data transmission rate. Before feeding the LPS data stream into the modulator, each LPS bit is encoded into a symbol sequence using sequence mapping. This approach, together with the coherent MF reception, equips the LPS channel with an extremely high robustness against channel noise and multipath propagation. To handle every possible redundancy in the received signal and to minimize the possibility of making wrong decisions, a data correction block is also introduced. Initially, a rough estimation of the received HPS DCSK bit is done at the receiver, then this estimation is used to remove the DCSK modulation from the received information-bearing signal. The three inputs of data correction blocks are: (i) the reference and (ii) the information-bearing parts of the received signal in their original form, and (iii) the received information-bearing signal where the DCSK modulation is removed. The data correction block improves the BER performance while the increased channel capacity, enabled by the double-stream approach, improves the spectral efficiency. Analytical expressions are derived to predict the BER performances in additive white Gaussian noise channel for both the LPS and HPS channels. Computer simulations are used to show that the system performance of the CSF-SM-DCSK modulation scheme proposed in this work is superior to that of the already published solutions. In addition to the computer simulations, the new chaos-based wireless communications system has been implemented on a wireless open-access research platform to experimentally demonstrate the feasibility and the superiority of CSF-SM-DCSK.

Binary Polarization Shift Keying With Reconfigurable Intelligent Surfaces

We propose a novel binary polarization shift keying modulation scheme for a line-of-sight environment by exploiting the polarization control ability of the reconfigurable intelligent surface (RIS). The RIS encodes the information data in terms of the polarization states of either the reflected wave from the RIS or the composite wireless channel between an RF source and receiver. In the first case, polarization mismatch correction becomes essential at the receiver. In the second case, the RIS pre-codes the reflected wave to compensate for the polarization mismatch which allows non-coherent demodulation at the receiver.