Non-coherent Modulation Schemes Research Articles

Chaotic Spread-Spectrum Communication: A Comparative Study between Chaotic Synchronization and Matched Filtering

This publication investigates the performance of demodulation methods utilized in spread spectrum chaotic communication systems, specifically matched filtering and chaotic synchronization. We conduct simulations and comparisons of three different communication systems: classic direct sequence spread spectrum (DSSS), chaotic signal fragment-based pseudo-chaotic spread spectrum (PCSS), and chaotic synchronization-based antipodal chaos shift keying (ACSK). These systems possess similar spectral and time domain characteristics, allowing us to shed light on their fundamental differences and limitations. Additionally, we assess the impact of frequency modulation (FM) on these modulation methods, as FM allows the creation of simplified non-coherent modulation schemes. Our findings, based on the analysis of bit error ratio (BER) curves, clearly demonstrate that the utilization of quantized waveforms for spreading confers a significant advantage over analogous, continuous-time spread spectrum systems. In addition, it is shown that the employment of chaotic synchronization instead of cross-correlation does not degrade the performance of the communication system and provides a more secure approach. In general, this research aims to enhance awareness regarding the distinct advantages and limitations associated with chaotic spread spectrum modulation methods.

On Performance Analysis of Wireless Network over Double Shadowed Rician Fading Channel

In the wireless network, many physical conditions may arise where received signal power is shadowed by moving objects along the propagation paths, and further shadowing of the received signal may result from moving objects around the transmitters or receivers. This phenomenon is mathematically modelled in terms of the double (or dual) shadowing process brought about by fading channels where both dominant and scattered wave components fluctuate together. In this present study, the outcome aspects of dual-shadowed wireless fading channels are explored in accordance with outage analysis, channel capacity, and average bit error rate (ABER) for coherent as well as non-coherent modulation schemes. Here, the Rician envelope, which undergoes two shadowing effects, is assumed. The channel format described here is such that both dominant and scattered signals are impacted by the Nakagami m random variable (RV). As a model, the mathematical expressions are derived for channel capacity, outage analysis, and ABER for dual-shadowed Rician fading channels. The effects of different shadowing parameters are explored, and corresponding results are plotted. All the evaluative results are recognised by emulating the simulation results for various values of the fading parameters.

Different Power Adaptive Transmission Schemes Over Alternate Rician Shadowed Fading Channels

The two-sided bimodality property of Alternate Rician Shadowed (ARS) fading channels makes it a suitable fading model for body-centric wireless communication. The ARS fading model consists of two fluctuating specular components in which only one is active at a time. To provide excellent spectral efficiency with higher quality of service, system transmitter employs an adaptive transmission scheme. This paper derives the exact closed-form expressions of the ARS fading channels capacity. Various adaptive transmission schemes such as channel inversion with a fixed-rate, truncated channel inversion with a fixed-rate, and optimal rate adaptation are considered. A comparison of these schemes is also highlighted. Performance expressions such as binary bit error rate for various coherent and non-coherent modulation schemes and the outage probability are also derived. The derived results are plotted and analyzed for varying fading parameters of the ARS channel. Finally, the results of all performance metrics are verified with Monte-Carlo simulation results.

Performance Analysis of I/Q Imbalance With Hardware Impairments Over Hyper Fox’s H-Fading Channels

Impairments baseband model in-phase and quadrature-phase Imbalance (IQI) and Residual hardware impairments (RHI) are two key factors degrading the performance of wireless communication systems (WCSs), particularly when high-frequency bands are employed, as in 5G systems and beyond. The impact of either IQI or RHI on the performance of various WCSs has been investigated exclusively in a separate way. To fill this gap, in this paper, the joint effect of both IQI and RHI on the performance of a WCS subject to Hyper Fox’s H-fading (HFHF) channel, is investigated. Such a fading model generalizes most, if not all, of well-known fading and turbulence models. To this end, closed-form expressions for the outage probability (OP), Average channel capacity (ACC) under constant power with optimum rate adaptation (ORA) policy, and average symbol error probability (ASEP) for both coherent and non-coherent modulation schemes are derived. Specifically, all the analytical expressions are derived for three different scenarios: (i) ideal Tx and Rx impaired, (ii) Tx impaired and ideal Rx, and (iii) both Tx and Rx are impaired. Further, asymptotic expressions for OP, ACC under ORA policy, and ASEP are obtained, based on which, insightful discussions on the IQI and RHI impacts are made. <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha -\mu $ </tex-math></inline-formula> and Málaga <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathcal {M}$ </tex-math></inline-formula> turbulence with pointing error distribution models have been considered as particular cases of the HFHF distribution. The analytical derivations, endorsed by simulation results, demonstrate that the RF impairments’ effects should be seriously taken into account in the design of next-generation wireless technologies.

NC-OFDM-SPM: A Two-Dimensional Non-Coherent Modulation Scheme for Achieving the Coherent Performance of OFDM along with Sending an Additional Data-stream

A promising candidate solution for reducing complexity in future wireless systems is the use of non-coherent designs; however, it is very well known in the literature that non-coherent schemes perform worse than their coherent counterparts. To address this longstanding challenging trade-off, we demonstrate and prove in this work the ability of the proposed two-dimensional modulation scheme termed as non-coherent orthogonal frequency division multiplexing with subcarrier power modulation and differential phase shift keying in achieving the performance of a coherent design, while reducing complexity. Although the proposed design is non-coherent (i.e., it uses differential phase shift keying and power difference to convey information), it achieves the same bit error rate (BER) performance as conventional OFDM with coherent BPSK. Furthermore, since the proposed scheme employs two-dimensional modulations simultaneously (i.e., DPSK and subcarrier power levels), an additional data stream can be transmitted through the power subcarriers’ levels. Thus, the proposed design not only solves the trade-off between coherent and non-coherent modulations in terms of reliability by achieving the same BER, but also provides higher data rates by exploring the power domain as an additional dimension for conveying extra data bits, while maintaining low complexity transceiver design, thus making it very appealing for IoT applications.

On the ASER Performance of UAV-Based Communication Systems for QAM Schemes

In this letter, we derive an average symbol error rate (ASER) expression of rectangular quadrature amplitude modulation (RQAM) scheme for unmanned aerial vehicle-enabled communication systems operating over double-shadowing and double-scattering composite fading channel. A moment generating function for the receiver output signal-to-noise ratio is obtained to analyze the ASER expression of non-coherent modulation schemes. An asymptotic expression of ASER for RQAM scheme is also derived to examine diversity order of the considered system. Further, the impact of composite fading parameters and path loss on ASER performance is highlighted. Finally, we validate all the theoretical results through Monte Carlo simulations.

A 0.6-mW 16-FSK Receiver Achieving a Sensitivity of −103 dBm at 100 kb/s

This article presents an RF receiver (RX) designed to exploit the inherent SNR advantage offered by non-coherent 16-FSK modulation relative to more conventional non-coherent modulation schemes, such as FSK and OOK. Specifically, this article demonstrates that when demodulated using two-pole bandpass filters, 16-FSK offers a 4-dB sensitivity advantage compared with binary frequency shift keying (BFSK), at the cost of reduced spectral efficiency at the same data rate. This article then presents the design of a 16-FSK-compatible RX front end, which performs demodulation through 16 N-path filters driven by temperature-stabilized phase-locked loops to ensure calibration-free filter center frequency control, along with augmented Miller capacitors for tight area-constrained bandwidth control. Implemented in 65-nm CMOS, the RX consumes 0.6 mW from a 0.5-V supply while achieving a sensitivity of -103.2 dBm at 100 kb/s, for a power-sensitivity-data-rate figure of merit of 185.2 dB, which represents a 3.2 dB advance over state of the art.

The $\alpha$-$\mathcal {F}$ Composite Fading Distribution: Statistical Characterization and Applications

In this paper, the $\alpha$ - $\mathcal {F}$ composite fading distribution is introduced. It is worth highlighting that the $\alpha$ - $\mathcal {F}$ distribution offers more flexibility as it includes the composite $\mathcal {F}$ and the $\alpha$ - $\mu$ distributions, and their inclusive ones, as special cases. Moreover, unlike the composite $\mathcal {F}$ and the $\alpha$ - $\mu$ distributions, the $\alpha$ - $\mathcal {F}$ distribution jointly considers two important effects, namely the shadowing and the non-linearity of the propagation medium. Novel exact closed-form expressions for the probability density function (PDF), cumulative density function (CDF), moment-generating function, and higher order moments of the instantaneous signal-to-noise ratio are derived. The PDF and CDF are then employed to analyze the performance of a wireless communication system. To this end, we derive closed-form expressions for the outage probability, average channel capacity, and average bit error rate for binary coherent and non-coherent modulation schemes as well as for $M$ -ary modulation schemes. The analytical results are verified through numerical and Monte-Carlo simulations. The results demonstrate that the system performance improves as the non-linearity of the propagation medium and (or) the multipath parameter increase(s). Additionally, the system performance improves as the shadowing parameter increases. To demonstrate practical applications of the $\alpha$ - $\mathcal {F}$ distribution, we apply it to realistic channel measurements obtained for two different wireless emerging applications, namely underwater acoustic and device-to-device communications. The results demonstrate that the PDF of the $\alpha$ - $\mathcal {F}$ distribution provide a good fit to the measured data PDFs compared with other well-known distributions, namely $\mathcal {K}$ , $\kappa$ - $\mu$ shadowed, and $\alpha$ - $\mu$ distributions.

On the outage probability and BER of a DF-based multi-hop system over [formula omitted] and [formula omitted]-extreme fading channels

This paper analyzes the performance of decode-and-forward (DF)-based multi-hop relaying communication systems over α-κ-μ and α-κ-μ-Extreme fading channels. Analytical formulas for the probability density function (PDF) and the cumulative distribution function (CDF) of the received signal-to-noise ratio (SNR) as well as its moment generating function (MGF) are derived. Based on the derived PDFs, novel closed-form expressions for the outage probability (OP), bit error rate (BER) under coherent and non-coherent modulation schemes are derived. Additionally, asymptotic analyses of BER based on Poincare series expansions of SNR PDFs are carried out and results show good approximations for low SNR regimes. Simulations are performed to verify the accuracy and to show the tightness of the theoretical analysis.

Non-coherent OFDM-Subcarrier Power Modulation for Low Complexity and High Throughput IoT Applications

Aiming to reduce the transceiver complexity and power consumption of communication systems dedicated to serving future Internet of Things (IoT) applications, researchers have taken many approaches with varying degrees of success. A promising candidate solution that can reduce complexity significantly and thus also enhance power-saving is the use of non-coherent modulation-based schemes. Utilizing a non-coherent structure rids the system of any dependency on the knowledge of the phase of the transmitted signal during demodulation. However, although most of the available non-coherent techniques in the literature reduce the complexity of the system, they, unfortunately, suffer from a drawback of some sort, especially in reducing the overall spectral efficiency of the system. To address this problem, we propose a new non-coherent modulation scheme called orthogonal frequency division multiplexing with subcarrier power modulation and differential phase-shift keying (OFDM-SPM-DPSK), as an effective modulation technique for future 6G and beyond systems. The proposed technique has the potential to reduce complexity, enhance power-saving while improving spectral efficiency significantly, resulting in a spectral efficiency performance twice that of a conventional non-coherent OFDM system. Furthermore, receive diversity is implemented through maximal ratio combining to overcome the bit error degradation brought by the adoption of a non-coherent structure. Additionally, the computational complexity is discussed and shown to be as efficient as OFDM, where the proposed scheme does not add further complexity over conventional OFDM.

Performance of dual-branch selection combining receiver over Fluctuating Two-Ray (FTR) fading channels for 5G mmWave communications

The fluctuating two-ray (FTR) fading channels is a suitable model of small-scale fading environment for fifth-generation millimeter-wave and beyond communications. This paper evaluates the performance of selection combining (SC) of the received signals through an independent FTR fading channels. A dual-branch SC receiver is considered because of its lower complexity and significant improvement from the non-diversity system. The probability distribution function (PDF) expression of the received signal to noise ratio (SNR) of the SC receiver is obtained from the cumulative distribution function of SNR for FTR fading channels. The average bit error rate of coherent and non-coherent modulation schemes are derived using the obtained received PDF expression. The impacts of the fading parameters on the performance of the system are analyzed numerically. The numerically estimated expressions are verified with standard outcomes and Monte Carlo simulation.

DIVERSITY SIGNAL PROCESSING OVER WEIBULL FADING CHANNELS

We present a moments-based approach to the performance analysis of L-branch equal-gain combining and maximal-ratio combining receivers, operating in independent or correlated, not necessarily identically distributed, Weibull fading. For both equal-gain combining and maximal-ratio combining receivers the moments of the output signal-to-noise ratio are obtained in closed-form. An accurate approximate expression is derived for the moment-generating function of the output signal-to-noise ratio of the equal-gain combining receiver utilizing the Padé approximants theory, while a closed-form expression for the corresponding MGF of the maximal-ratio combining receiver, is obtained. Significant performance criteria, such as average output signal-to-noise ratio, amount of fading and spectral efficiency at the low power regime, are extracted in closed-forms, using the moments of the output signal-to-noise ratio for both independent and correlative fading. Moreover, using the well-known moment-generating function approach, the outage and the average symbol error probability for several coherent, non-coherent, binary, and multilevel modulation schemes, are studied. The average symbol error probability of dual-branch equal-gain combining and maximal-ratio combining receivers is also obtained when correlative fading is considered in the diversity input branches. The proposed mathematical analysis is illustrated by various numerical results and validated by computer simulations.

A novel project‐and‐forward relay‐assisted mixed RF‐FSO system design and its performance evaluation

AbstractThe outage and error performance of a radio frequency (RF)‐free space optical (FSO) asymmetric two‐hop link using project‐and‐forward relaying protocol is evaluated in this paper. We suggest a multiple‐input–multiple‐output (MIMO)‐RF channel with multiple source and relay antennas for simultaneous transmission over the RF link followed by an FSO channel that supports point‐to‐point transmission over a single FSO link. Furthermore, the source to relay RF link is modeled by Nakagami‐m fading distribution to represent different channel fading conditions often encountered in various applications, while the FSO channel is affected by atmospheric turbulence characterized by Gamma‐Gamma fading, path loss, and misalignment errors. The performance of the system is investigated considering the impact of these parameters. We derive the mathematical expressions that are obtained in closed form for the probability density function and cumulative distribution function of the instantaneous signal‐to‐noise ratio for the Nakagami‐m faded MIMO‐RF link in terms of Meijer's G‐function. Using the aforementioned statistical results, we derive a novel closed‐form expression for the outage probability of the system. We also evaluate the average‐bit‐error‐rate performance for different coherent and noncoherent modulation schemes, and obtain novel mathematical results in closed form for the same.

Average SEP and channel capacity analysis over Generic/IG composite fading channels: A unified approach

This paper develops an analytical framework to analyse important performance metrics of the wireless communication system over generic fading channels characterized by α−μ/Inverse Gaussian (IG), η−μ/IG, and κ−μ/IG distributions. The important performance metrics, namely, the outage probability (OP), the amount of fading (AOF), the average symbol error probability (SEP) of coherent and non-coherent schemes, the channel capacity under optimal rate adaptation (ORA), channel inversion with fixed rate (CIFR), and truncated CIFR (TCIFR) policy are analysed. Further, low and high signal-to-noise-ratio (SNR) approximations for channel capacity are presented. Furthermore, for asymptotic analysis the approximate composite probability density function (PDF) at the origin was developed and utilized to derive the closed-form expressions for the average SEP of both coherent and non-coherent modulation schemes with maximal ratio combining (MRC), equal gain combining (EGC), and selection combining (SC) diversity schemes. The proposed asymptotic solutions are simple and can be easily used to describe the system behaviour at high SNR. The correctness of the derived results has been verified by comparing them with Monte Carlo simulations.

Coded transmissions for space links affected by solar scintillation: Baseband analysis

SummaryA thorough analysis of the behavior of error‐correcting codes over space links affected by solar scintillation is presented. The relevant channel parameters are fixed through the development of a model based on real missions' data. Both telecommand and telemetry links are considered in fast and slow fading conditions. Besides classical coherent modulation schemes, the possibility to use noncoherent modulation schemes is considered, to eliminate the problem of phase tracking. For the case of channels with very slow fading, the use of external interleavers or erasure coding is proposed to cope with error bursts.

Performance Analysis of SWIPT Relay Networks With Noncoherent Modulation

In this paper, we investigate the performance of noncoherent modulation in simultaneous wireless information and power transfer (SWIPT) relay networks. Noncoherent modulation schemes eliminate the need for instantaneous channel state information estimation, and therefore, minimize the overall energy consumption of the network. In particular, we adopt a moments-based approach to develop a comprehensive novel analytical framework for the analysis of the outage probability, achievable throughput, and average symbol error rate (ASER) of a dual-hop SWIPT relay system considering the time switching (TS) and power splitting (PS) receiver architectures. In addition, through the derivation of new asymptotic analytical results for the outage probability and ASER, we analytically demonstrate that the diversity order of the considered system is non-integer less than 1 in the high signal-to-noise (SNR) regime. Our results show that there is a unique value for the PS ratio that minimizes the outage probability of the system, while this is not the case for the TS protocol. We also demonstrate that, in terms of system throughput, the TS relaying scheme is superior to the PS relaying scheme at lower SNR values. An extensive Monte Carlo simulation study is presented to corroborate the proposed analytical model.

Backscatter Multiplicative Multiple-Access Systems: Fundamental Limits and Practical Design

In this paper, we consider a novel ambient backscatter multiple-access system, where a receiver (Rx) simultaneously detects the signals transmitted from an active transmitter (Tx) and a backscatter tag. Specifically, the information-carrying signal sent by the Tx arrives at the Rx through two wireless channels: the direct channel from the Tx to the Rx and the backscatter channel from the Tx to the tag and then to the Rx. The received signal from the backscatter channel also carries the tag's information because of the multiplicative backscatter operation at the tag. This multiple-access system introduces a new channel model referred to as backscatter multiplicative multiple-access channel (BM-MAC). We analyze the achievable rate region of the BM-MAC and prove that its region is strictly larger than that of the conventional time-division multiple-access scheme in many cases, including, e.g., the high SNR regime and the case when the direct channel is much stronger than the backscatter channel. Hence, the multiplicative multiple-access scheme is an attractive technique to improve the throughput for ambient backscatter communication systems. Moreover, we analyze the detection error rates for coherent and noncoherent modulation schemes adopted by the Tx and the tag, respectively, in both synchronous and asynchronous scenarios, which further bring interesting insights for practical system design.

Performance analysis of shadowed-Rice fading channel with cooperative spectrum sensing

ABSTRACTIn this paper, the performance analysis of wireless communication system over shadowed-Rice (SR) composite fading channel has been investigated and analysed. The unified analytical expressions of the average symbol error probability (ASEP) for several coherent and non-coherent modulation schemes separately with different constellation sizes are derived for composite fading channel under two different fade mitigation methods, with maximal ratio combining (MRC) microdiversity (Method 1) and MRC applied over the composite fading channel (Method 2). Furthermore, an asymptotic analysis is carried out and a closed-form expression of the ASEP with Method 2 is presented. Analytical expressions of the corresponding average probability of energy detection (PD) are formulated for both the methods. Finally, the derived PD expression is utilised to analyse the performance of cooperative system assuming erroneous feedback channel. Analysis of optimisation of detection threshold as well as number of cognitive users to minimise the total error rate is also carried out. The closed-form expressions are validated by comparing them with exact numerical results and Monte Carlo simulation.

Non-Coherent Spatial Modulation and Optimal Multi-Ring APSK Constellation Design

A non-coherent spatial modulation scheme assuming no channel state information (CSI) at the receiver is proposed in this letter. Different from the differential spatial modulation, in which the difference between the previous information block and the current information block is employed, the proposed scheme only utilizes the estimation of the previous transmission block to eliminate the restriction of CSI. Moreover, a generalized multi-ring amplitude phase shift keying (APSK) constellation with arbitrary modulation order of PSK on each circle is used in the scheme, and the optimal one is found through the design method proposed in this letter. Simulation results show that, at the same spectral efficiency, the proposed scheme with optimal constellation outperforms the scheme with traditional PSK, QAM, and existing APSK in Rayleigh fading channel.

Performance Analysis of Coherent and Non-Coherent Modulation Schemes in Faded Wireless Channels using ANN-assisted MRC

Performance Analysis of Coherent and Non-Coherent Modulation Schemes in Faded Wireless Channels using ANN-assisted MRC