Noncoherent Binary Frequency Shift Keying Research Articles

Performance analysis of a RIS-assisted RoFSO communication system over Malaga distribution for smart city applications.

Radio over free space optics (RoFSO) is one of the potential technologies that can satisfy the requirements of 5G services in a smart city. However, as RoFSO is line-of-sight (LOS) communication, one of its limitations is the occurrence of a skip zone in the targeted areas. In this work, a reconfigurable intelligent surface (RIS) is proposed as the solution to overcome this connection difficulty, which prevents signal blocking by generating LOS connections. These RIS modules extend the communication channel coverage, making it more intelligent and controllable. The performance analysis based on outage probability, ergodic channel capacity, and bit error rate has been performed using heterodyne detection. Malaga distribution has been used to model atmospheric turbulence. The exact closed-form expressions of the probability density function and cumulative distribution function of the end-to-end signal-to-noise ratio are derived. Exploiting these derived statistics, system performance is investigated through the ergodic channel capacity, outage probability, and average bit error rate for M-ary quadrature amplitude modulation and two binary modulation schemes: non-coherent binary frequency-shift keying and coherent binary phase-shift keying. Numerical results are compared among different turbulence conditions, link lengths, and scattering errors. The results show that the proposed RIS-assisted RoFSO technology has the potential to be effective for 5G smart city applications.

Performance of Reconfigurable-Intelligent-Surface-Assisted Satellite Quasi-Stationary Aircraft–Terrestrial Laser Communication System

This paper proposes the use of quasi-stationary aircraft and reconfigurable intelligent surfaces (RIS) to improve the system performance in satellite–terrestrial laser communication downlink. Single-input multiple-output (SIMO) technology is applied to the relay node of a quasi-stationary aircraft. The closed expression of the bit error rate (BER) of an RIS-assisted satellite quasi-stationary aircraft–terrestrial laser communication system (RIS-SHTLC) is derived under the M-distributed atmospheric turbulence model while considering the influence of atmospheric turbulence and pointing errors caused by RIS jitter. The effects of coherent binary frequency shift keying (CBFSK), coherent binary phase-shift keying (CBPSK), non-coherent binary frequency shift keying (NBFSK), and differential binary phase-shift keying (DBPSK) on the performance of an RIS-SHTLC system are simulated and analyzed under weak turbulence. The results show that the RIS-SHTLC system with CBPSK modulation has the best communication performance. Simultaneously, the relationships between the average signal-to-noise ratio (SNR) and BER of the RIS-SHTLC system under different RIS elements are simulated and analyzed, and compared with the traditional SHTLC system. In addition, the influence of the zenith angle, receiving aperture and divergence angle on the performance of the system is studied. Finally, Monte Carlo simulations are used to validate the analytical results.

Performance analysis of multiple access relay channels for non-coherent modulations

One of the most important applications of network coding is the Multiple Access Relay Channel (MARC) technique in which source terminals transmit independent data blocks over one or more relay terminals to a common destination terminal. In recent years, MARC has become one of the vital network coding applications in the area of innovative wireless cooperative communications for enhancing spectral efficiency. In this paper, non-coherent binary frequency shift keying (BFSK) modulation and differential binary phase shift keying (DPSK) modulation techniques are applied to the decode-and-forward (DF)-based MARC model and the average bit error rate (BER) of the proposed system is derived theoretically by using the maximum likelihood (ML) decision rule. The simulation results show that the BER performance of DPSK modulation is better than the non-coherent BFSK and full diversity gain is achieved in both modulation techniques. We also propose a power allocation scheme for the proposed system model which optimizes the power allocated to the source and relay transmissions. Depending on the location of the relay, performance gains up to 1.25 dB are achieved with the proposed optimum power allocation (OPA) scheme. Also, the mathematical derivations are verified through Monte-Carlo simulations and the superior performance of the OPA over equal power allocation (EPA) is observed.

Performance of a bi-directional relaying system with one full duplex relay

Full duplex communication system has the potential to double the spectral efficiency compared to traditional half duplex communication system. However self interference in full duplex relay is considered as the major concern to the performance of system. In this paper, performance of two way relaying communication system is studied with a full duplex relay. Specifically, the probability density function (PDF) of the signal-to-interference-plus-noise ratio (SINR) is derived. By using the derived PDF, closed form expressions for average bit error rate (BER) is derived for various binary modulation schemes such as, coherent binary phase shift keying (BPSK), differential BPSK, coherent binary frequency shift keying (BFSK), and non-coherent BFSK. Moreover, the ergodic capacity of the considered system is also analyzed.

BER performance and data throughput of body sensor networks for reliable biological signal transmission over the human body

According to the IEEE 802.15 task group 6, human body communication (HBC) is a wireless body area network (WBAN) that operates at frequency band 5–50 MHz. In particular, communication between nodes is through body surface to body surface, and the human body acts as the transmission channel. This paper designs the link budget signaling parameters required for reliable transmission of biological signals over the IEEE 802.15.6a HBC channel model, and investigates the bit-error-rate (BER) and data throughput performances of different modulation schemes. These modulation schemes include non-coherent binary frequency shift keying (NcBFSK) with non-coherent detection, in addition to the commonly used schemes for HBC communications, namely coherent binary phase shift keying (CBPSK), coherent binary frequency shift keying (CBFSK), and on-off keying (OOK). According to the numerical results based on theoretical analysis, experimental results, as well as Monte-Carlo simulations, NcBFSK with non-coherent detection and bandwidth-integration window product , CBPSK, CBFSK, and OOK, represent appropriate solutions for the reliable transmission of biological signals over HBC-based WBANs. The results are based on and 1 Mbps data rate for low data rate applications, and and data rate = 10 Mbps for high data rate applications.

Exact BER Performance Analysis of Link Adaptive Relaying with Noncoherent BFSK Modulation

Link adaptive relaying (LAR) is one of the most popular techniques developed for mitigating error propagation in decode and forward (DF) based cooperative wireless networks which employs soft power scaling approaches at the relay nodes. On the other side, frequency shift keying (FSK) is a prominent technique for eliminating the need for channel estimation by training sequences which increases complexity of the system and causes reduction in the transmission rate in proportional to the number of users involved in the network. In this paper, performance of an LAR scheme with noncoherent binary FSK (BFSK) signaling is investigated by deriving exact closed form bit error rate expressions in Rayleigh fading channels.

An Ultra Low Energy FSK Receiver With In-Band Interference Robustness Exploiting a Three-Phase Chirped LO

An ultra-low-energy Binary Frequency Shift Keying (BFSK) receiver is proposed. It features improved in-band interference tolerance by chirping the transmission frequency. To reduce the receiver power consumption, a novel three-phase passive mixer along with a three stage digitally controlled ring oscillator is proposed, while still allowing quadrature detection. A mixer-first direct conversion receiver architecture moves the required gain to lowest frequency and lowest bandwidth to reduce power consumption. A low power flip-flop based BFSK demodulator is proposed that reduces the baseband power further. The receiver is designed and fabricated in a 65 nm complementary metal-oxide-semiconductor process. It consumes 219 μW from 1.2 V power supply, while having a sensitivity of -70 dBm for a bit error rate of 0.1% at 2.4 GHz. Except the off-chip 64 MHz clock generation, the total receiver requires 27 pJ/bit. Using a chirped clock spreading of 360 MHz and chirp repetition rate of 1 MHz, it can tolerate up to -8 dB signal to interference ratio for all interferer frequencies. This is 13.5 dB better than previously reported in literature and 12 dB better than ideal noncoherent BFSK receiver interference robustness.

SNR Estimation in a Non-Coherent BFSK Receiver With a Carrier Frequency Offset

This correspondence deals with the problem of estimating average signal-to-noise ratio (SNR) for a communication link employing binary frequency shift keying (BFSK) in the presence of a carrier frequency offset (CFO). The transmitted symbols are corrupted by Rayleigh fading and additive white Gaussian noise (AWGN). We treat the CFO as a nuisance parameter and estimate it using a data statistics based estimator. This estimate is then used to design a maximum likelihood (ML) estimator to get the estimates of SNR. We also derive the Cramér-Rao bound (CRB) for the estimators and have shown the performance of both the data-aided and non-data-aided estimators.

A New Approach to Bivariate Hoyt Distribution and its Application in Performance Analysis of Dual-Diversity Receivers

Novel infinite series based expressions for the bivariate Hoyt distribution are derived. More specifically, expressions for the joint probability density function (JPDF) and the joint cumulative distribution function (JCDF) of two Hoyt fading envelopes are derived, and proposed for use in performance analyses of dual-branch diversity receivers operating over correlated Hoyt fading channels. Using these reasonably simple and mathematically tractable expressions, we evaluate the performance of a dual-branch selection combining (SC) diversity receiver in terms of the outage probability (P out ) and the average bit error probability (ABEP) criteria. The ABEP performance is evaluated for binary differential phase-shift-keying (BDPSK) and binary non-coherent frequency-shift keying (BNFSK) modulation schemes.

On the performance of non-coherent transmission schemes with equal-gain combining in generalized Κ-fading

The generalized κ-fading model, characterized by two parameters, κ and m, is a very versatile model and was recently shown to accurately capture the effects of composite shadowing and multipath fading in wireless communication systems. Furthermore, it can be used to model cascade multipath fading, which is relevant in, e.g., mobile-to-mobile communication scenarios. In this paper, we derive closed-form expressions for the bit error probability of two non-coherent transmission schemes over L diversity branches being subject to generalized κ-fading. Specifically, focus is on binary differential phase-shift keying (DPSK) and binary non-coherent frequency-shift keying (FSK) modulation with (post-detection) equal-gain combining at the receiver. We also discuss the extension of our results to M-ary modulation schemes. Considering both independent and correlated fading across the L branches, we derive expressions for the asymptotic diversity order, which reveal an interesting interplay between the two fading parameters κ and m. Moreover, we show that the diversity order of the considered non-coherent transmission schemes is the same as in the case of a coherent transmission scheme. Finally, numerical performance results are presented, and our analytical results are corroborated by means of Monte-Carlo simulations.

Average BER analysis for binary signallings in decode-and-forward dissimilar cooperative diversity networks

In this letter, the average bit-error rate (BER) performance is analyzed for uncoded decode-and-forward (DF) cooperative diversity networks. We consider two typical networks: a single-relay cooperative network with the direct source destination link and a two-relay cooperative network with the direct source-destination link, under dissimilar network settings, i.e., the fading channels of different relay branches may have different variances. We first derive a closed-form approximate average BER expression of binary signallings including noncoherent binary frequency shift keying (BFSK), coherent BFSK, and coherent binary phase shift keying (BPSK), for the single relay network. We then generalize our analysis to the two-relay network, and a closed-form approximate average BER expression for binary signallings is derived. We also show that our BER expressions can be considered as generalizations of previously reported results in the literature. Throughout our analysis, only one approximation, so-called the piecewise-linear approximation, is made. Simulation results are in excellent agreement with the theoretical analysis, which validates our proposed BER expressions.

Envelope and phase distribution of two correlated gaussian variables

Probability density functions (pdf's) are derived for the phase and amplitude (envelope) of the complex gain X +jY (j = radic-1), where X and Y are two correlated non zero-mean Gaussian random variables. The pdf of the amplitude is derived as an infinite series, but reduces to a closed-form expression when the means are zero. The classical Rayleigh and Rician pdf's turn out to be special cases of the derived pdf. This pdf is used to analyze the error performance of non-coherent binary frequency shift keying (BFSK) with in-phase/quadrature(I/Q) imbalance over an additive white Gaussian noise (AWGN) channel. The resulting bit error rate (BER) expression is derived as an infinite series. The analytical expressions are validated by simulation, and the I/Q imbalance related performance degradation is quantified. Convergence of the PDF series and the BER series is established.

Blind and Semi-Blind Decoder Metrics for Turbo-Coded Frequency-Hopped Spread-Spectrum in Partial-Band Interference and Fading Channels

We consider turbo-coded frequency-hopped systems operating in partial-band interference and fading channels under conditions which make Signal-to-Noise Ratio (SNR) estimation difficult or infeasible. For Non-Coherent Binary Frequency Shift Keying (NCBFSK) we propose blind decoder metrics that offer significant performance gains over the conventional self-normalized metric originally proposed for non-fading channels and uncoded communications. We also propose several blind heuristic metrics for phase-compensated Binary Phase Shift Keying (BPSK) systems of varying complexity and performance. For both NCBFSK and CBPSK we then derive the exact conditional LLR given the second---order averages of the interference and noise, which we refer to as semi-blind metrics. Impressive performance gains are realized in both cases. For BPSK the best totally blind heuristic metric nearly achieves the performance of the exact conditional LLR and has the advantage of not requiring any statistics on interference or noise. In all cases the performance gains are most pronounced for small values of the interference duty factor.

Diversity Combining and SNR Estimation for Turbo-Coded Frequency-Hopped Spread-Spectrum in Partial-Band Interference and Fading Channels

We compare different combinations of the repetition diversity order L and code rate R for turbo-coded Frequency-Hopped Spread-Spectrum (FH/SS) communication systems in the presence of fading and partial-band Gaussian interference. For a fixed overall channel code rate R/L we show that using the lowest code rate and no repetition diversity always performs better than using a higher code rate and some repetition for both coherent and non-coherent schemes. We then propose a simple maximum-likelihood-based method for signal-to-noise-ratio (SNR) estimation in Non-Coherent Binary Frequency Shift Keying (NCBFSK) without training symbols. Except for impractically small hop sizes of 8 bits or less we obtain performance virtually equal to that of perfect SNR knowledge but with much less complexity than iterative schemes previously proposed. For the case of Coherent Binary Phase Shift Keying (CBPSK) we derive the Expectation Maximization (EM) estimate of the SNR without training symbols and iteratively feed the estimator with the extrinsic information from the turbo decoder. The performance for CBPSK is near that of perfect SNR knowledge for hop sizes of 64 bits or more. Unlike previously proposed methods for CBPSK the EM estimate of SNR does not require knowledge of the noise and interference variance, received bit energy, or the fading channel model.

An EM approach to multiple-access interference mitigation in asynchronous slow FHSS systems

In this paper, we apply the EM algorithm for mitigation of multi-access interference (MAI) in asynchronous slow frequency-hop spread spectrum (FHSS) systems that employ binary frequency-shift keying (BFSK) modulation. MAI occurs if the hopping patterns of the users are not orthogonal. We show that when FSK signals arrive asynchronously, the time offset exposes portions of the desired and interfering signals in a way that can be exploited to improve the decoder performance. We develop an iterative detection, estimation, and decoding scheme to recover the desired signal in the presence of MAI. We compare the performance of this algorithm with that of a conventional noncoherent BFSK transceiver and show that the EM-based algorithm is particularly effective in the presence of strong interfering signals and allows more users in a FHSS system.

Narrowband Interference Suppression in Frequency-Hopping Spread Spectrum Using Undecimated Wavelet Packet Transform

Suppression of narrowband interference in frequency-hopping spread spectrum (FH-SS) systems is treated in this paper. First, we analyze the effect of continuous-wave tone interference in noncoherent binary frequency-shift keying (BFSK) signaling with FH-SS. Based on this analysis, a new receiver for FH-SS systems is proposed, including a transform-domain interference suppression module. The algorithm is executed in two steps: 1) interference detection and 2) signal reconstruction. The novelty of this suppression algorithm is the combination of the undecimated wavelet packet transform with frequency shifts of the received signal to center the narrowband interference in a subband. Once the subband that contains the interference has been determined, the algorithm removes this subband and then reconstructs the signal. The performance of this receiver has been evaluated in a variety of situations with different types of narrowband interference. The results obtained show the improvement of the proposed receiver in comparison to the traditional FH-SS receiver.

Performance of Two Dual-Branch Postdetection Switch-and-Stay Combining Schemes in Correlated Rayleigh and Rician Fading

The performance of binary frequency-shift keying (BFSK) and M-ary frequency shift keying (MFSK) with dual-branch postdetection switch-and-stay combining (SSC) in correlated Rayleigh and Rician fading is studied. Two postdetection SSC receivers are considered and the performances of noncoherent BFSK and MFSK are analyzed. Closed-form expressions are derived for the average bit-error rate (BER) of BFSK and MFSK with postdetection SSC in correlated Rayleigh and Rician fading. Optimum switching thresholds that minimize the average BER are obtained. Extensive Monte Carlo simulations are presented to test the validity of the analytical results. The performance of dual-branch postdetection SSC is compared with the performance of dual-branch predetection SSC. The effects of correlation, fading parameter, average fading power imbalance, and switching threshold on the performances of postdetection SSC receivers are examined

Further Results on Selection Combining of Binary NCFSK Signals in Rayleigh Fading Channels

In this paper, we provide an analytical performance comparison of various selection combining (SC) schemes for binary noncoherent frequency-shift keying (NCFSK) signals operating on independent and nonidentically distributed (i.n.d.) Rayleigh fading channels. With this motivation, we first derive the receiver structure for the optimum SC scheme, which combines one out of the available L diversity branches so as to minimize the probability of bit error. We show that the optimum SC scheme chooses the diversity branch having the largest magnitude of the logarithm of the a posteriori probability ratio (LAPPR) of the transmitted information bit. We also show that: 1) the optimum noncoherent diversity receiver, for binary NCFSK signals, is equivalent to combining the LAPPRs of all the diversity branches; 2) the SC scheme proposed by Neasmith and Beaulieu is a special case of the optimum SC scheme for independent and identically distributed (i.i.d.) Rayleigh fading; and 3) for i.n.d. fading with dual diversity (i.e., L=2), the performance of the optimum SC scheme is the same as that of the optimum noncoherent diversity receiver, whereas the Neasmith and Beaulieu SC scheme gives the performance of the suboptimum equal gain combining receiver. Bit-error rate (BER) results show that, at 10/sup -4/ BER, for i.i.d. Rayleigh fading, the proposed optimum SC scheme performs better than the existing SC schemes by 0.5-0.9 dB for L=3 and by 0.8-1.5 dB for L=5, and performs within 0.3 dB of the optimum noncoherent diversity receiver for L=3,5, and for i.n.d. Rayleigh fading with L=5, the optimum SC scheme gives an additional gain of about 2.0 dB over the Pierce SC scheme. Further, for i.i.d. Rayleigh fading, we derive the bit-error probability expression for a (3,L) selection scheme which combines three branches whose LAPPR magnitudes are the largest among the available L branches. Numerical results for this (3,L) selection scheme show that for L=5 at a BER of 10/sup -4/, combining the three branches with the largest LAPPR magnitudes yields almost the full performance of the optimum noncoherent diversity receiver, whereas, for L=7, it is just about 0.2 dB away from the latter.

Semianalytical simulation for evaluation of block-error rates on fading channels

A semianalytical (SA) simulation method is proposed as a means to improve the efficiency of computer simulation in estimating block-error rates (BKERs) in the presence of Doppler fading and additive white Gaussian noise. Frequency-nonselective Rayleigh, Rician, and Nakagami fading with diversity combining for binary noncoherent frequency-shift keying (NCFSK) modulation are considered. The reduction in required computer simulation time of the SA method compared to the conventional Monte Carlo (MC) simulation is assessed.

Switched diversity on microcellular Ricean channels

The performances of switched dual diversity systems operating on independent and correlated Ricean fading channels are analyzed using a discrete time model. The average bit error rate (BER) of the discrete time switched diversity system using binary noncoherent frequency shift keying (NCFSK) on slow, nonselective Ricean fading channels is derived. A closed form expression that gives the optimum switching threshold in a minimum error rate sense is derived for the case of independent branch signals. Results for the optimum switching threshold for the case of correlated branch signals, obtained numerically, are also presented. Results using selection diversity combining are obtained for comparison. The effects of fading severity on both the BER and on the optimum switching threshold are investigated. The Ricean fading model may be used to model both the microcellular radio environment and the mobile satellite fading channel. Hence, the results of the paper are useful for both of these areas. >