Coherent Phase Shift Keying Research Articles

Adding RLL Properties to Four CCSDS LDPC Codes without Increasing Their Redundancy

This paper presents the construction of Run Length Limited (RLL) Error Control Codes (ECCs) from four Low Density Parity Check (LDPC) Codes specified by Consultative Committee for Space Data Systems (CCSDS). The obtained RLL-ECCs present a practical alternative to the CCSDS codes with pseudo-randomizers. Their advantage is that the maximal runlengths of equal symbols in their codeword sequences are guaranteed, which is not the case if the common approach with pseudo-randomizers is used. The other advantages are that no additional redundancy is introduced into encoded codewords and that the encoding and decoding procedures of the original error control CCSDS codes do not have to be modified in the following cases. In the first case if hard decoding is used and the transmission channel can be modeled as a Binary Symmetric Channel (BSC) or in the second case if soft decoding and coherent Binary Phase Shift Keying (BPSK) modulation is used and the appropriate transmission channel model is an Additive White Gaussian Noise (AWGN) channel.

Error Probability of a Coherent M-ary PSK FSO System Influenced by Phase Noise

In this paper, we aim to develop an analytical framework for design and analysis of new generation mobile networks fronthaul/backhaul links based on the application of free-space optical (FSO) technology. Taking the receiver hardware imperfections into account, we present an efficient analytical approach in analyzing average symbol error probability (SEP) of the coherent FSO system employing M-ary phase-shift keying (PSK). Optical signal transmission is influenced by pointing errors and atmospheric turbulence. The signal intensity fluctuations caused by atmospheric turbulence are modeled by general Málaga (M) distribution, which takes into account the effect of multiple scattered components. We estimate the range of the signal-to-noise ratio at which the SEP floor appears, as well as the value of this non-removable error floor. The results illustrate that the effect of imperfect phase error compensation on the SEP is more critical under weaker turbulence conditions and for higher order modulation formats. Based on the analytical tools presented here, it is possible to estimate tolerable value of standard deviation of phase noise for the given value of SEP. This value of standard deviation is an important parameter in designing the phase-locked loop filter in the receiver.

Effective Model for Real Time End to End Secure Communication Over GSM Voice Channel

Due to the availability, robustness and reliability; Global System for Mobile Communications (GSM) plays a vital role in our daily life. GSM security is not so strong and is susceptible to attacks. One of the most important issues is insecurity in voice communicated over the GSM. While the system provides limited voice security over air links through encryption; yet, availability of a solution, that provides end-to-end secure voice assurance, is considered important to meet user security requirements. To make the communication secure (end-to-end) one option is to encrypt the speech and then transmit it over GSM channel. In this paper, a novel approach is proposed for secure end-to-end voice communication over GSM. The biggest challenge is that the GSM channel only transmits speech like a symbol; therefore, a modulation technique is required which can effectively generate modulation signal similar to the human voice. Next problem in this regard is the requirement of associated encryption and speech compression technique. The proposed methodology uses codec2 700 bits/s as an encoder and decoder, with coherent PSK as a modulation and demodulation technique. In addition to this KASUMI based encryption algorithm is adopted which best fits in our proposed flow. The quality assessment of the speech after its reconstruction on the receiver side has shown good results. The proposed methodology has shown viable results on the computer-based system as well as an embedded system.

Defending wireless communication against eavesdropping attacks using secret spreading codes and artificial interference

The broadcast nature of wireless communication makes it intrinsically vulnerable to eavesdropping attacks. This article suggests the using of secret spreading codes (i.e. only a legitimate receiver knows the spreading sequence) and artificial interference (i.e. by intentionally adding noise to the broadcast channel) on countering eavesdropping attacks. We have made a theoretical analysis on the potential performance degradation at the eavesdropper and at the legitimate receiver for a point-to-point wireless communication system using direct-sequence spread spectrum (DSSS) with coherent phase-shift keying (PSK) modulation. We have also proposed a lightweight non-cryptographic secret code generation scheme which leads to low correlation between the spreading codes used at the transmitter and at the eavesdropper. Simulation results confirms the good anti-eavesdropping performance on using the proposed non-cryptographic secret code generation scheme. Simulation results also conform with the theoretical analysis and motivate the using of artificial interference on countering eavesdropping attacks.

Receiver Energy Efficiency and Transmission Latency Analysis of Outage-Constrained Differential PSK With a Finite Resolution ADC

We consider a power constrained downlink communication scenario where energy efficiency, reliability, and latency take precedence over rate, as in some Internet of Things (IoT) applications. To reduce its receiver power consumption and complexity, we assume that the IoT device has a single RF chain and investigate the finite-resolution analog-to-digital converter (ADC) operation with differential Phase Shift Keying (PSK) modulation. A lower ADC resolution leads to an exponential decrease in power consumption, while adopting differential PSK enables the use of a low-cost detector with no channel state information (CSI) or carrier phase recovery circuitry. Our main goal in this article is to compare, both analytically and numerically using representative IoT system design parameters, the receiver energy efficiency of the proposed differential PSK system with a coherent PSK system that uses estimated CSI under reliability and latency constraints in Rayleigh slow-fading and ADC quantization distortion conditions. To mitigate the ADC finite-resolution effects without requiring CSI at the receiver or transmitter, we propose and analyze a PSK differentially-modulated Alamouti space-time block transmission scheme with only two RF chains at the transmitter while still restricting the IoT device to have a single RF chain. Our results demonstrate that in the considered low-rate, and outage and latency-constrained scenario with stringent power consumption requirements, differentially-modulated Alamouti transmissions to a single RF-chain IoT device with a low-resolution ADC is an attractive choice in terms of receiver energy efficiency, reliability, and transmission latency.

Fundamental Limits of Quantum-Secure Covert Communication Over Bosonic Channels

We investigate the fundamental limit of quantum-secure covert communication over the lossy thermal noise bosonic channel, the quantum-mechanical model underlying many practical channels. We assume that the adversary has unlimited quantum information processing capabilities as well as access to all transmitted photons that do not reach the legitimate receiver. Given existence of noise that is uncontrolled by the adversary, the square root law (SRL) governs covert communication: up to $c\sqrt {n}$ covert bits can be transmitted reliably in $n$ channel uses. Attempting to surpass this limit results in detection with unity probability as $n\rightarrow \infty $ . Here we present the expression for $c$ , characterizing the SRL for the bosonic channel. We also prove that discrete-valued coherent state quadrature phase shift keying (QPSK) constellation achieves the optimal $c$ , which is the same as that achieved by a circularly-symmetric complex-valued Gaussian prior on coherent state amplitude. Finally, while binary phase shift keying (BPSK) achieves the Holevo capacity for non-covert bosonic channels in the low received signal-to-noise ratio regime, we show that it is strictly sub-optimal for covert communication.

Digital coherent PSK Y-00 quantum stream cipher with 217 randomized phase levels.

We report a 10-Gbaud fiber-optic cipher transmission system by using a phase-shift keying (PSK) Y-00 quantum stream cipher. The PSK Y-00 cipher is a symmetric-key direct data encryption technique based on extremely high-order random phase modulation using a pre-shared short key. Neighboring signal phases following encryption are masked by quantum (shot) noise, which provides security based on shot noise's inherent effects. To implement such a system, we utilize coarse-to-fine phase modulation with two cascaded phase modulators and digital decryption incorporated into digital signal processing (DSP) for intra-dyne coherent detection. We demonstrate 10-Gbaud PSK Y-00 cipher transmission over a 400-km standard single-mode fiber (SSMF). The coarse-to-fine phase modulation achieves 217 phase levels for signal masking by shot noise. The DSP with decryption realizes detection of the cipher without penalties. Masking 167 signal phase levels by shot noise is achieved at a bit-error ratio defined by a hard-decision forward-error correction threshold (3.8 × 10-3) in the transmissions over the 400-km SSMF.

Coherent quadrature phase shift keying optical communication systems

Coherent optical fiber communications for data rates of 100 Gbit/s and beyond have recently been studied extensively because high sensitivity of coherent receivers could extend the transmission distance. Spectrally efficient modulation techniques such as M-ary phase shift keying (PSK) can be employed for coherent optical links. The integration of multi-level modulation formats based on coherent technologies with wavelength-division multiplexed (WDM) systems is vital to meet the aggregate bandwidth demand. This paper reviews coherent quadrature PSK (QPSK) systems to scale the network capacity and maximum reach of coherent optical communication systems to accommodate traffic growth.

Average BER and Noisy Reference Loss of Partially Coherent PSK Demodulation Over Shadowed Multipath Fading Channel

In this correspondence paper, we present novel results related to the error performance of coherent systems in the presence of the imperfect carrier phase estimation over Gamma shadowed Nakagami- $m$ fading environment. Taking the Tikhonov-distributed phase error process into account, binary and quaternary phase-shift keying signal detection is analyzed. Based on the Maclaurin series expansion of the complementary error function, approximated closed-form expressions for the bit error rate (BER) are derived. These expressions are simplified to those already reported in literature, which are valid in the case without shadowing. The asymptotic closed-form expressions for noisy reference loss are also presented. We examine the effect of phase-locked loop parameters on both BER and noisy reference loss. Analytical results are validated by independent Monte Carlo simulations.

CDF and MGF based analysis over Rayleigh TWDP shadowed fading channel for indoor communication

ABSTRACTRecently, the two-wave with diffuse power (TWDP) distribution has been extensively used to model the shadowing in multipath-faded/shadowed indoor environment. In this article, novel expressions for joint moments, mean, second moment, variance and cumulative distribution function for Rayleigh TWDP shadowed fading model are derived. By using the derived expression of mean and variance, the expression for amount of fading is obtained. Also, the outage probability, moment generating function and average bit error rate (ABER) for various modulation schemes namely binary phase shift keying (BPSK), binary frequency shift keying (BFSK), minimum shift keying (MSK), differentially coherent phase shift keying (DCPSK) and non-coherent frequency shift keying (NCFSK) are calculated. The derived expressions for cumulative distribution function, outage probability and ABER are presented in analytical format and have been numerically evaluated. Moreover, the numerical results of ABER using MSK and DPSK modulation schemes is compare with results of Rayleigh Gamma composite fading model. The study shows that better outage probability (0.01) is observed at 40dB average signal to noise ratio (SNR) with 5dB lowest threshold SNR, however, at higher threshold SNR (>5dB) with fixed average SNR (40dB), poor outage probability performance are obtained. Further, at higher shadowing (10dB), for fixed average SNR (15dB), minimum error probability (10−4) is observe, while at lower shadowing (less than 10dB), higher error probability (greater than 10−4) is observed that represents poor BER performance.

On the Average Achievable Rate of QPSK and DQPSK OFDM Over Rapidly Fading Channels

Motivated by recent experimental observations, where differentially coherent detection outperforms coherent detection on certain underwater acoustic channels, we revisit the performance of these two methods with respect to the achievable rate in orthogonal frequency-division multiplexing systems. Our comparison is based on a class of time-varying channels, where coherent quadrature phase shift keying (QPSK) detection requires channel estimation through a set of designated pilot symbols, while differentially coherent QPSK (DQPSK) enjoys an almost pilot-free detection. We show that given the cost of pilot overhead and channel estimation errors, the average rate achievable with DQPSK can be higher than that of QPSK. We use analytical results to identify channels for which this is the case, and expand the results to larger constellation sizes such as 8PSK, 16PSK, and 16QAM. In addition to acoustic channels, wireless radio channels with unusually long delay spread or high Doppler spread, such as those found in unmanned aerial systems and high-speed trains, may also benefit from using differentially coherent detection. In general, differentially coherent detection is favored in rapidly time-varying channels which require large pilot overhead and/or whose bit error rate performance is dominated by channel estimation errors. Our analysis includes the results for array receivers and soft detectors, showing that the favorable parameter range for differentially coherent detection expands significantly in both cases.

On the Statistics of the Error Propagation Effect of Binary Differential Phase-Shift Keying

We study a traditional problem related to binary differentially coherent phase-shift keying (DPSK) modulation, where an error in a symbol tends to cause an error in the next symbol; this phenomenon is referred to as error propagation. We derive the double bit-error rate (DBER) of two successive DPSK symbols over additive white Gaussian noise and Rician fading. Our findings show that the DBER decreases as the signal-to-noise ratio increases. A tight closed-form upper bound for the average DBER over a slowly varying Rician channel is also presented to simplify the numerical evaluation.

On the error rate of coherent binary modulation techniques in mobile communication systems over generalized fading channels impaired by generalized Gaussian noise

In the this paper, the performance of coherent binary digital modulation techniques is investigated. Specifically, we derive exact closed-form expressions for the average bit error rate (BER) of coherent binary phase shift keying (BPSK) and frequency shift keying (BFSK) in the α-μ fading channels impaired by generalized Gaussian noise. The derived expressions take into account the mobility of the wireless receiver. In this paper, we employ the random waypoint (RWP) model to study the effect of mobility on the system performance. Some representative analytical results are presented to investigate the effects of the fading parameters, noise shaping parameter, and network topology on the system performance. In addition, Monte-Carlo simulations are provided to validate the accuracy of the analytical results.

Design and Performance Investigation of Intersatellite Optical Wireless Communication System Employing Modulation Techniques

This work is focused to carry out the investigation of coherent optical quadrature phase shift keying (CO-QPSK), coherent optical quadrature amplitude modulation (CO-QAM), CO-8-QAM, CO-8-PSK, CO-16-QAM and CO-16-PSK techniques on intersatellite optical wireless communication system using OptiSPICE and OptiSystem at 1550, 1064 and 850 nm. The maximum bit rate achieved for CO-QPSK and CO-QAM is 0.511 Tbps, CO-8-QAM and CO-8-PSK is 0.742 Tbps and CO-16-QAM and CO-16-PSK is 1 Tbps at maximum distance of 45,000 km. The performance of CO-16-PSK is better than other proposed techniques in terms of quality (Q) factor at 1550, 1064 and 850 nm wavelengths. There is 59.93, 27.95, 16.58, 7.26 and 4.26 % improvement in CO-16-PSK from CO-QPSK, CO-QAM, CO-8-QAM, CO-8-PSK and CO-16-QAM respectively in terms of signal to noise ratio (SNR) at 1550 nm wavelength. On comparing all the techniques, it is found that at acceptable bit error rate 0---10ź7, CO-16-PSK is better technique as compared to other proposed techniques in terms of bit rate, Q factor and SNR.

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.

Chaos‐based BPSK communication system

A novel broadband chaos-based coherent binary phase shift keying (BPSK) communication system is proposed and it is demonstrated that its theoretical probability of error expression matches that of a conventional narrowband BPSK system. The result is confirmed with the corresponding empirical bit error rate (BER) simulation. Most importantly, it is shown that the proposed system outperforms the chaotic communication systems in terms of BER while also being more practicable. The proposed system thus holds high promise as the chaotic communication systems pose implementation difficulties, lack robust synchronisation techniques and are generally considered of academic interest only.

Prototype of Uplink Transceiver for IFDMA-PON System by FPGA Emulation

We demonstrate a power-efficient coherent interleaved frequency domain multiple access passive optical network (IFDMA-PON) uplink system. The digital signal processing circuits for coherent IFDMA-based quadrature phase-shift keying (PSK) are implemented on 40-nm field programmable gate arrays. By employing polar-coordinate transformed mapping of the PSK signal, the power consumption of the optical network unit is reduced to one-tenth that of conventional orthogonal frequency-division multiple access-PON systems. The transmission of a 6 Gb/s real-time coherent IFDMA-PON uplink signal across 20 km of single mode fiber is demonstrated for the first time.

Parity Check Encoded QPSK for Rate Adaptation in Coherent DSP-Based Receivers

An ultrashort rate-1/2 parity check (PC) code is used to switch the net data rate of a coherent quadrature phase shift keying (QPSK) transmission system to the equivalent of a binary phase shift keying (BPSK) system. Simulation results of PC encoded-QPSK show an improvement in receiver sensitivity of 0.8 dB over BPSK at the soft-FEC threshold of BER = 2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> . In addition, the code allows establishing an absolute phase reference at the receiver; i.e., differential coding is not required.

Performance of M-QAM, M-DPSK and M-PSK with MRC diversity in a Nakagami-m fading channel

The nature of a wireless communication channel is very unpredictable. To design a good communication link, it is required to know the statistical model of the channel accurately. The average symbol error probability (ASER) was analyzed for different modulation schemes. A unified analytical framework was presented to obtain closed-form solutions for calculating the ASER of M-ary differential phase-shift keying (M-DPSK), coherent M-ary phase-shift keying (M-PSK), and quadrature amplitude modulation (QAM) over single or multiple Nakagami-m fading channels. Moreover, the ASER was estimated and evaluated by using the maximal ratio-combining (MRC) diversity technique. Simulation results show that an error rate of the fading channel typically depends on Nakagami parameters (m), space diversity (N), and symbol rate (M). A comparison between M-PSK, M-DPSK, and M-QAM modulation schemes was shown, and the results prove that M-ary QAM (M-QAM) demonstrates better performance compared to M-DPSK and M-PSK under all fading and non-fading conditions.