Smaller Bit Error Rate Research Articles

Determination of the Bit Error Rate Due to Thermal Noise Using JoSIM Superconducting Circuit Simulator and the Monte Carlo Method

Thermal noise requires careful consideration during the design process of RSFQ circuits since it reduces circuit operating margins and can cause switching errors. Bit error rate (BER) provides a useful means of analysing the effect of this noise on a circuit. With tools developed under the IARPA SuperTools project, we present an implementation of the Monte-Carlo technique for determining BER via simulation. The Monte-Carlo method has been considered previously but not widely implemented due to slow simulation times preventing the determination of small BER values. We use JoSIM – an efficient simulator with SPICE syntax that allows for the simulation of superconducting components and noise sources with improved speed over older superconductor simulators. This speed improvement makes the Monte-Carlo method viable. The simulated BER is plotted against bias current with values in the low-BER region interpolated from the simulated values using MATLAB. We show how the results need to be used as a further qualifier of circuit performance for the characterization of a logic cell library.

Performance Evaluation of OTFS and OFDM for 6G Waveform

Orthogonal time frequency space (OTFS) modulation is a coming technique addressing the challenges of 5G and 6G. It’s appeared to bring about outstanding error performance in delay – Doppler (DeDo) channels. Still, a really fair comparison with its competitor's direct orthogonal frequency division multiplexing and is extensively used in this participation, we will make a comparison of the performance of OTFS and OFDM with the digital modulation format in terms of bit error rate (BER) versus signal-to-noise rate (SNR) for the 16- QAM technique. From the numerical simulations under MATLAB, the results showed that the OTFS admits a small BER to the OFDM in given cases

Continuous variable B92 quantum key distribution protocol using single photon added and subtracted coherent states

In this paper, a continuous variable B92 quantum key distribution (QKD) protocol is proposed using single photon added and subtracted coherent states, which are prepared by adding and subsequently subtracting a single photon on a coherent state. It is established that in contrast to the traditional discrete variable B92 protocol, this protocol for QKD is intrinsically robust against the unambiguous state discrimination attack, which circumvents the requirement for any uninformative states or entanglement used in corresponding discrete variable case as a remedy for this attack. Further, it is shown that the proposed protocol is intrinsically robust against the eavesdropping strategies exploiting classical communication during basis reconciliation, such as beam splitter attack. Security against some individual attacks, key rate, and bit-error rate estimation for the proposed scheme are also provided. Specifically, the proposed scheme ensures very small bit-error rate due to properties of the states used. Thus, the proposed scheme is shown to be preferable over the corresponding discrete variable B92 protocol as well as some similar continuous variable quantum key distribution schemes.

Solar Scintillation Effect for Optical Waves Propagating Through Gamma–Gamma Coronal Turbulence Channels

Optical communication is a promising strategy for deep space exploration but it is susceptible to coronal solar wind turbulence impairments during superior solar conjunction. The variance of amplitude fluctuations caused by coronal turbulence on optical waves propagation is proposed in this paper. Both the generalized non-Kolmogorov coronal turbulence spectrum and the aperture averaging effect are taken into account. The analytic expression of the bit error rate (BER) for free-space optical (FSO) link is then derived based on Gamma–Gamma distribution model under the weak-to-moderate coronal turbulence channels. Numerical evaluations results demonstrate that coronal turbulence with small non-Kolmogorov spectral index, large outer scale, and inner scale has more potential to deduce amplitude fluctuations. With the increment of antenna radius, the amplitude fluctuations decrease obviously. In addition, the variation tendencies of these parameters can further result in small BER. Therefore, the link performance will be improved by decreasing the optical wavelength and enlarging the antenna radius. Our proposed amplitude fluctuations model with aperture averaging effect has potential application for the future deep space FSO communication.

BER performance analysis of coarsely quantized uplink massive MIMO

Abstract Having lower quantization resolution, has been introduced in the literature, to reduce the power consumption of massive MIMO and millimeter wave MIMO systems. Here, we analyze the bit error rate (BER) performance of quantized uplink massive MIMO employing few-bit resolution ADCs. Considering ZF detection, we derive a signal-to-interference, quantization and noise ratio (SIQNR) to achieve an analytical BER approximation for coarsely quantized M-QAM massive MIMO systems, by using a linear quantization model. The proposed expression is a function of the quantization resolution in bits. We further numerically investigate the effects of different quantization levels, from 1-bit to 4-bits, on the BER of three modulation types QPSK, 16-QAM, and 64-QAM. The uniform and non-uniform quantizers are employed in our simulation. Monte Carlo simulation results reveal that our approximate formula gives a tight upper bound on the BER performance of b-bit resolution quantized systems using non-uniform quantizers, whereas the use of uniform quantizers cause a lower performance. We also found a small BER performance degradation in coarsely quantized systems, for example 2–3 bits QPSK and 3–4 bits 16-QAM, compared to the full-precision (unquantized) case. However, this performance degradation can be compensated by increasing the number of antennas at the BS.

Design of Cyclic Prefix Characteristic-Based OFDM System for WiMAX Technology

Worldwide interoperability for microwave access (WiMAX) offers the wireless connectivity using orthogonal frequency division multiplexing (OFDM) modulation is a proficient wireless technology that capacities high-speed data transmission facilities. The existing WiMAX techniques have the problem of increase in inter-symbol interference (ISI) and bit error rate (BER) at reduced power spectrum that degrades the performance of WiMAX system due to high data rate transmission. The utilization of different adaptive modulation techniques seen as a potential solution to reduce the ISI and BER for high data rate transmission. In this paper, OFDM is adapted using advanced modulation technique for WiMAX system. The technique proposes the cyclic prefix (CP) is utilized that include supplementary bits at the stage of the transmitter. The proposed technique offers minimization of ISI and improvement in BER. It is defined that performance of the existing CP system is equated with the designed single cyclic prefix (SCP) and double cyclic prefix (DCP) and non-cyclic prefix (NCP). BER, probability of error, and power spectral density are utilized to analyse the performance of the designed system. The OFDM based SCP and DCP and NCP for WiMAX are demonstrated for modulation techniques such as; QPSK, BPSK, and QAM. It is determined that BPSK has the smallest BER when compared to QPSK, 16-QAM, and 64-QAM modulations. It is also demonstrated that QPSK is also very competent, however, it has a higher BER as compared to BPSK modulation. It is also observed that 16-QAM and 64-QAM are less efficient in terms of BER compared to QPSK and BPKS modulations. 64-QAM offers the high data rates, and due to high SNR ratio. The designed system is tested for under AWGN and Rayleigh fading channel, and effect power spectral density of signal to noise ratio on OFDM for rayleigh fading channel are demonstrated for SCP and DCP and NCP. It is determined that the OFDM transmitter with proposed DCP for random signals is efficiently reducing the BER and ISI for WiMAX system.

Performance of OFDM-Based WiMAX System Using Cyclic Prefix

The WiMax (Worldwide Interoperability for Microwave Access) is a technology in<strong> </strong>broadband wireless access, which employs OFDM (Orthogonal Frequency Division Multiplexing) as an alternative transmission to enable high speed data in communication system. This research aim is to analyze the performance system of the OFDM-Based WiMAX, which used the cyclic prefix. The model was designed in four schemes of simulation method, the BPSK (Binary Phase Shift Keying, QPSK (Quadrature Phase Shift Keying), 16 QAM (Quadrature Amplitude Modulation) and 64 QAM. Each scheme was investigated BER (Bit Error Rate) on AWGN (Additive White Gaussian Noise) channel and multipath Rayleigh fading channel, which had applied the cyclic prefix. By simulation of the cyclic prefix was produced the modulation measurement of the BPSK, QPSK, 16 and 64 QAM. The performance result of Eb/No 15 dB was obtained the BER of BPSK and QPSK of 1.11E-11, the BER of 16 QAM and 64 QAM of 8.69E-06 and 0.00333 respectively. Those results indicated much smaller BER value than EbNo 0 dB which BPSK and QPSK of 1 BER, 1.5 and 1.75 BER for 16 QAM and 64 QAM respectively. In conclusion, a higher value of EbNo, hence the BER value would be lower.

Green Distributed Quality of Transmission Aware Routing and Wavelength Assignment in All-Optical Networks

Abstract The Routing and Wavelength Assignment (RWA) algorithms that consider quality of transmission (QoT) in light-path setup spend more time than their conventional counterparts due to exhaustive search and QoT estimation. This paper proposes distributed Quality of Transmission Aware Routing and Wavelength Assignment (QARWA) algorithm to handle dynamic light-path provisioning in wavelength routed all-optical networks taking energy consumption of optical switch nodes into account. Specifically, the QARWA considers bit-error rate (BER), setup delay, and energy consumption constraints at the same time, and establishes light-paths with small BER, low setup latency, and reduced energy consumption. We present and evaluate an enhanced wavelength-assignment solution in the QARWA to handle the wavelength continuity constraint. In QARWA, a source node determines the connection path by means of the shortest path algorithm and a destination node selects a wavelength based on the BER limitation and decreasing order of setup latency. Relating energy consumption to processing time, we show that QARWA can decrease the total energy consumption by reducing the processing time at each node. Under QARWA, when a node finishes the processing of the last control packet, it makes transition to either sleep state or idle state. Hence, QARWA can provide the best performance since it can reduce processing time in control units, light-path setup latency, and energy consumption of nodes.

Proportional bandwidth adjustment using BER ratios, in a two‐tier hierarchical NEMO system

AbstractIn this paper, we present a proportional bandwidth adjustment (PBA) scheme using bit‐error‐rate (BER) ratios in a two‐tier hierarchical NEMO system, composed of an access router (AR), mobile routers (MRs), and visiting mobile nodes (MNs). Depending on the location, an MN may use direct link to AR (Tier‐0) or indirect link to AR via MR (Tier‐1). To increase system utilization, sessions generated by high‐speed MNs in one tier are allowed to use a certain amount of free bandwidth in another tier. Since Tier‐1 traffic can be temporarily buffered at MR, to reduce the blocking probability of Tier‐0, the bandwidth between Tier‐0 and Tier‐1 can be proportionally adjusted based on BER. In other words, more bandwidth is allocated to the tier with smaller BER. For the purpose of performance evaluation, we build a mathematical model with 6D Markov chains to analyze session blocking probabilities, system utilization, and normalized goodput. Analytical results are validated through a simulation. Both results demonstrate that the proposed PBA can significantly reduce the session blocking probabilities and increase the overall normalized goodput when BER ratio between Tier‐0 and Tier‐1 is very different. Copyright © 2010 John Wiley & Sons, Ltd.

Analysis and Efficient Evaluation of the BER of OSTBCs With Imperfect Channel Estimation in Arbitrarily Correlated Fading Channels

An analysis of the exact bit error rate (BER) performance of orthogonal space-time block codes (OSTBCs) with maximum-likelihood detection in the presence of channel estimation errors is presented. The possibly correlated coefficients of the multiple-input multiple-output (MIMO) propagation channel are assumed to be affected by flat block fading and the transmitted symbols belong to a pulse amplitude modulation or quadrature amplitude modulation signal constellation. For both square and nonsquare OSTBCs, we derive approximate and exact BER expressions, irrespective of the distribution of the fading. It is also shown how the exact expressions can be efficiently and accurately evaluated using numerical integration techniques. Their application to the arbitrarily correlated Nakagami-m fading channel is presented and an efficient importance sampling technique is derived. As the high diversity order resulting from the application of OSTBCs gives rise to small BER values, the numerical evaluation of the presented BER expressions is much faster than straightforward Monte Carlo simulations. BER results have shown the impact of both imperfect channel estimation and antenna correlation on the performance of MIMO OSTBC systems. It is also shown that under highly correlated conditions, antenna correlation is the major source of BER degradation.

An Iterative Soft Bit Error Rate Estimation of Any Digital Communication Systems Using a Nonparametric Probability Density Function

In general, performance of communication system receivers cannot be calculated analytically. The bit error rate (BER) is thus computed using the Monte Carlo (MC) simulation (Bit Error Counting). It is shown that if we wish to have reliable results with good precision, the total number of transmitted data must be conversely proportional to the product of the true BER by the relative error of estimate. Consequently, for small BERs, simulation results take excessively long computing time depending on the complexity of the receiver. In this paper, we suggest a new means of estimating the BER. This method is based on an estimation, in an iterative and nonparametric way, of the probability density function (pdf) of the soft decision of the received bit. We will show that the hard decision is not needed to compute the BER and the total number of transmitted data needed is very small compared to the classical MC simulation. Consequently, computing time is reduced drastically. Some theoretical results are also given to prove the convergence of this new method in the sense of mean square error (MSE) criterion. Simulation results of the suggested BER are given using a simple synchronous CDMA system.

Information Theoretic Foundations of Adaptive Coded Modulation

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> In wireless/mobile communications, terminals adapt their rate and transmit power or, more in general, their coding and modulation scheme, depending on the time-varying channel conditions. This paper presents, in a tutorial form, the information theoretic framework underlying such “adaptive modulation” techniques. First, we review fading channel models, channel state information assumptions, and related capacity results. Then, we treat the case of input power constraint, where the optimal input distribution is Gaussian. Finally, we address the case of discrete modulations. In order to treat the latter, we make use of the recently developed method of “mercury-waterfilling,” based on the relationship between mutual information and minimum mean-square error (MMSE) estimation of the channel input from the channel output. While the traditional design of adaptive modulation schemes based on uncoded bit-error rate (BER) involves the optimization over a discrete set of signal constellations, when powerful (i.e., capacity approaching) coding schemes are used the corresponding adaptive coded modulation design becomes surprisingly simple. The regime of very powerful coding is justified by the use of modern coding schemes, such as turbo codes and low-density parity-check codes, able to perform close to channel capacity at very small BER. </para>

Modified sum-product algorithms for decoding low-density parity-check codes

The authors deal with the sum-product algorithm (SPA) based on the hyperbolic tangent (tanh) rule when it is applied for decoding low-density parity-check (LDPC) codes. Motivated by the finding that, because of the large number of multiplications required by the algorithm, an overflow in the decoder may occur, two novel modifications of the tanh function (and its inverse) are proposed. By means of computer simulations, both methods are evaluated using random-based LDPC codes with binary phase shift keying (BPSK) signals transmitted over the additive white Gaussian noise (AWGN) channel. It is shown that the proposed modifications improve the bit error rate (BER) performance up to 1 dB with respect to the conventional SPA. These results have also shown that the error floor is removed at BER lower than 10 -6 . Furthermore, two novel approximations are presented to reduce the computational complexity of the tanh function (and its inverse), based on either a piecewise linear function or a quantisation table. It is shown that the proposed approximations can slightly improve the BER performance (up to 0.13 dB) in the former case, whereas small BER performance degradation is observed (<0.25 dB) in the latter case. In both cases, however, the decoding complexity is reduced significantly

On the effects of receiver windowing on OFDM performance in the presence of carrier frequency offset

An exact bit error rate (BER) expression for an OFDM system with windowing reception is derived. The effects of several Nyquist windows, including the raised-cosine window, the than raised-cosine (BTRC) window, the second order continuity window (SOCW), the Franks window, and the double-jump window on the performance of the system are examined based on both BER measure and signal-to-interference (SIR) measure. It is found that the SIR comparison is not necessarily consistent with the BER comparison. The BTRC windowing gives the smallest BER among the five windowing functions considered for small to medium values of pulse roll-off factor. However, the Franks windowing or SOCW windowing shows better BER performance when the roll-off factor approaches one

Semiblind EM-Based Iterative Receivers for Space–Time-Coded Modulation and Quasi-Static Frequency-Selective Fading Channels

This paper introduces two different iterative receivers for space-time-coded data transmitted through frequency-selective fading channels. Both receivers perform maximum a posteriori data detection and decoding, and operate semiblindly by making use of the expectation maximization (EM) algorithm to estimate the unknown channel. The first receiver utilizes a supertrellis to jointly describe the channel and the code, while in the second one, this description is accomplished with two separated trellises. The two approaches are compared in terms of trellis complexity, achievable diversity level, and bit error rate (BER). The supertrellis approach is less computationally demanding and has a faster convergence rate, while the separate approach can achieve a higher diversity level and thus a smaller BER. This tradeoff is explored with examples and computer simulations, which show that, in many cases, the supertrellis approach can be a better solution than the separate approach

Design and Operation of a Pulse-Number Multiplier for a High-Precision RSFQ D/A Converter

A pulse-number multiplier (PNM) is a principal subsystem of our rapid single flux quantum digital-to-analog converter for metrology applications. The PNM circuit generates a high-speed pulse train from an input of a precise low-frequency clock signal. We designed, fabricated, and successfully tested a PNM test circuit. The PNM test circuit was implemented by using our standard cell library on 1.6 kA/cm/sup 2/ Nb trilayer technology. Fully functional operation was confirmed by low-speed testing. Experimental bias margins were wider than /spl plusmn/20%, and these results agreed with a simulation. We also tested the circuit by average-voltage measurements for estimating the frequencies of output pulse trains. Results of average-voltage measurements implied that the output frequency of the PNM circuit was tunable from 5 GHz to 17 GHz. The bit error rate (BER) of the PNM circuit was measured, and extrapolation of the error-function fits suggested a sufficiently small BER at the optimum bias point.

An Automated Method for BER Characteristics Measurement

Traditionally, the bit error rate (BER) characteristics were measured for a certain number of bit-energy-to-noise ratio ( Eb/No). For each point, a sample of r bits is used, which depends on the expected BER value. The smaller BER value, the bigger the sample r. Thus, to obtain the same accuracy at each point, a method of trial and error should be used. Therefore, this method extends the time of measurement and measures BER values at all points with different accuracy. This paper presents a method which allows the automated and accurate measurement of the BER characteristics at a number of points with equal accuracy at each point by using the minimum sample size r. The method is tested by measuring BER characteristics of an FFSK modem.

Demonstration of chip-to-chip propagation of single flux quantum pulses

We report experimental results on chip-to-chip transfer of single-flux-quantum (SFQ) pulses using an active multichip module (MCM). Josephson transmitters and receivers are integrated on both a chip and an MCM substrate. An MCM consisting of a 4.8-mm chip and an 8.2-mm MCM substrate was fabricated using a 1.6-kA/cm/sup 2/ Nb-trilayer process and a solder-bumped flip-chip bonding technology. The correct operation of the circuit was confirmed by low-speed testing. Bit-error rate (BER) of the circuit was measured down to 10/sup -5/, and extrapolation of the error-function fits suggested a very small BER, lower than 10/sup -200/, at the optimum bias point. Experimental margins on the bias voltage were as large as /spl plusmn/34%.

Multiphoton detection using visible light photon counter

Visible light photon counters feature noise-free avalanche multiplication and narrow pulse height distribution for single photon detection events. Such a well-defined pulse height distribution for a single photon detection event, combined with the fact that the avalanche multiplication is confined to a small area of the whole detector, opens up the possibility for the simultaneous detection of two photons. In this letter, we investigated this capability using twin photons generated by parametric down conversion, and present a high quantum efficiency (∼47%) detection of two photons with good time resolution (∼2 ns), which can be distinguished from a single-photon incidence with a small bit-error rate (∼0.63%).

MLSE for correlated diversity sources and unknown time-varying frequency-selective Rayleigh-fading channels

Yu and Pasupathy (see ibid., vol.43, p. 1534-44, 1995) derived a maximum-likelihood sequence estimation (MLSE) receiver structure for unknown time varying frequency-selective Rayleigh-fading channels and uncorrelated diversity sources. This receiver design is extended to the case of correlated diversity sources. Correlated diversity sources typically arise with space diversity, where constraints on antenna volume require that diversity antennae be placed too closely together. Analytic and simulated bit-error rate (BER) curves are presented for receivers which exploit and ignore the correlation. In the former case, we find a small BER improvement that reduces with decreasing correlation. However, for a fixed receiver complexity, superior performance is achieved when the correlation is ignored.