Binary Phase Shift Keying Signals Research Articles

On the likelihood-based approach to modulation classification

In this paper, likelihood-based algorithms are explored for linear digital modulation classification. Hybrid likelihood ratio test (HLRT)- and quasi HLRT (QHLRT)- based algorithms are examined, with signal amplitude, phase, and noise power as unknown parameters. The algorithm complexity is first investigated, and findings show that the HLRT suffers from very high complexity, whereas the QHLRT provides a reasonable solution. An upper bound on the performance of QHLRT-based algorithms, which employ unbiased and normally distributed non-data aided estimates of the unknown parameters, is proposed. This is referred to as the QHLRT-Upper Bound (QHLRT-UB). Classification of binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK) signals is presented as a case study. The Cramer-Rao Lower Bounds (CRBs) of non-data aided joint estimates of signal amplitude and phase, and noise power are derived for BPSK and QPSK signals, and further employed to obtain the QHLRT-UB. An upper bound on classification performance of any likelihood-based algorithms is also introduced. Method-of-moments (MoM) estimates of the unknown parameters are investigated and used to develop the QHLRT-based algorithm. Classification performance of this algorithm is compared with the upper bounds, as well as with the quasi Log-Likelihood Ratio (qLLR) and fourth-order cumulant based algorithms.

A novel scheme to generate multiband millimeter wave signals for 40 GHz full duplex radio-over-fiber system

This paper proposes a new scheme to generate frequency-diversity binary phase shift keying (BPSK) signals for radio-over-fiber (RoF) system. As is well known, the frequency diversity technology has the anti frequency selective fading characteristic and RoF system is a practical solution to increase the capacity and mobility of future-proof contents delivery and serve both fixed and mobile users. In this paper, our proposal can generate 20 GHz and 40 GHz millimeter-wave (mm-wave) signals simultaneously with the data rate of 1.25 Gbit/s employing only one electrical optical phase modulator (EOPM) and one Mach-Zehnder modulator (MZM) at the central station. With one additional MZM at the base station, the full duplex transmission can be accomplished. As the downstream data is phase modulated, the optical signal can be re-used to load the upstream data and no laser diode (LD) is needed at the base station, which simplify the structure of the base station. The 20 GHz electrical carrier is also generated which can be used to demodulate the BPSK signal. The whole scheme can be used in the future duplex RoF system.

Fully Digital BPSK Demodulator and Multilevel LSK Back Telemetry for Biomedical Implant Transceivers

A novel fully digital binary-phase-shift-keying (BPSK) transceiver for forward data telemetry and a multilevel load-shift-keying (LSK) transceiver for passive back telemetry are implemented. The digital architecture for the BPSK demodulator allows for much less power consumption compared with prior art. The basic premise of the demodulation is to regenerate the incoming BPSK signal using a digital phase-locked loop. We demonstrate the silicon realization of the BPSK demodulator operating at 13.56 MHz in a 0.5-mum complementary metal-oxide-semiconductor process with power consumption of 2.3 mW. The silicon area is 536 times 546 mum2. A novel multilevel LSK for passive back telemetry is implemented, and it works by modulating the load impedance at the implant to create distinct reflections at the primary coil of the reader. The reflections at the reader are decoded for data information using a discrete realization of highly sensitive LSK receiver. The simulation and measurement results indicate 2times improvement in data rate compared with conventional bilevel back telemetry. This brief also shows the implementation of a forward BPSK modulator based on a class-E power amplifier to complete a full biomedical implant transceiver implementation.

BER Calculation and Investigation of Optimal Single User Detector for a BPSK Signal Contaminated by Cochannel Interferer

We propose an optimal single user detector (OSUD) for a binary phase shift keying (BPSK) signal corrupted by a cochannel interferer and additive white Gaussian noise (AWGN). We obtain an analytical expression for the detector bit error rate (BER). The capacity of this channel is also investigated to interpret the BER performance of the optimal detectors.

Robust chaotic communications exploiting waveform diversity. Part 2: Complexity reduction and equalisation

The symbolic dynamics method of communication using chaotic systems has previously been shown to offer performance better than conventional binary phase shift keying (BPSK), while also providing similar spectrum efficiency. This is achieved by exploiting diversity in the waveform, through a mechanism similar to partial response signalling. In order to achieve this performance, a correlation method for detection has been proposed, but complexity was high and only performance in additive white Gaussian noise (AWGN) channels has been considered. It is demonstrated that the complexity can be reduced from requiring 1024 correlations per symbol down to only 32, while degrading performance only by 0.6 dB. The ability to further reduce the occupied bandwidth is investigated. Spectrum occupancy equivalent to a root-raised cosine-filtered BPSK signal is demonstrated, and performance is maintained when the reference waveforms are similarly filtered to maintain the signal match. Finally, a novel equalisation technique that incorporates a decision feedback structure into the correlation detector is proposed. Performance in multipath channels is investigated and shown to be effective.

BER Analysis of BPSK Signals in Ricean-Faded Cochannel Interference

The bit error rate of a binary phase shift keying (BPSK) signal in Ricean-faded cochannel interference is studied. A precise bit error rate expression is derived for a bandlimited BPSK signal corrupted by an arbitrary number of asynchronous Ricean-faded interfering signals. An error rate estimation based on a saddlepoint approximation is also provided. It is shown that this approximation is highly accurate. For the special case, when there is one synchronous Ricean-faded interfering signal in an interference-limited environment, an asymptotic error rate analysis based on the saddle point approximation reveals that fading in the cochannel interfering signal can have different impacts on the desired user's error rate performance. Our study shows that when the signal-to-interference ratio (SIR) is sufficiently large, the error floor of the desired user signal decreases with an increase of the Rice factor in the interfering user's fading channel. However, the opposite phenomenon can happen when the SIR is small.

스프레드스펙트럼통신방식을 적용한 RFID시스템 설계

본 논문에서는 유비쿼터스 환경에서 사용되는 RFID(Radio Frequency IDentification)시스템을 외부잡음에 강한 스프레드 스펙트럼(Spread Spectrum : SS)통신방식을 적용하여 설계하였다. 설계된 시스템은 수신기의 PLL과 송 수신기의 PN확산 변 복조를 할 수 있는 알고리즘과 안정적인 BPSK(Binary Phase Shift Keying)신호를 출력하도록 트랜지스터 증폭기를 설계하여 시스템을 구현하였다. 또한 제작이 편리한 마이크로스트립 협대역 패치 안테나를 설계하여 시스템에서 필터가 차지하는 부피를 줄였으며, RFID의 유통물류에 할당된 국제표준 주파수 대역인 <TEX>$860\sim930MHz$</TEX>의 UHF대역에 적용이 가능한 저전력 시스템으로 설계되었다. This paper implements RFID(radio-frequency identification)System to which the system was apply SS(Spread Spectrum) method. The system designed by using the algorithm for microprocessor with PLL of the receiver, PN spread, modulation and demodulation of the transceiver, and transistor amplifier for the output of stabilized BPSK (Binary Phase Shift Keying) signal. furthermore, it reduced the interference of the signal by designing the micro-strip narrow banded patch antenna, which is convenient for printing and producing, and decreased the volume of filter size in the system. It is also designed for the lower powered system with the possible application to UHF band of <TEX>$860\sim930MHz$</TEX> for the international standard frequency band, which is the quota share of RFID distribution system.

Simulation and analysis of OOK-to-BPSK format conversion based on gain-transparent SOA used as optical phase-modulator

All-optical on-off keying (OOK) to binary phase-shift keying (BPSK) modulation format conversion based on gain-transparent semiconductor optical amplifier (GT-SOA) is simulated and analyzed, where GT-SOA is used as an all-optical phase-modulator (PM). Numerical simulation of the phase modulation effect of GT-SOA is performed using a wideband dynamic model of GT-SOA and the quality of the BPSK signal is evaluated using the differential-phase-Q factor. Performance improvement by holding light injection is analyzed and non-return-to-zero (NRZ) and return-to-zero (RZ) modulation formats of the OOK signal are considered.

Signal activity detection of phase-shift keying signals

We propose computationally inexpensive and efficient solutions for signal activity detection of phase-shift keying (PSK) signals in additive white Gaussian noise. We consider the complex amplitude of the signal, as well as the information sequence, as the unknown parameters. In addition, the noise variance is assumed unknown. We derive the generalized likelihood ratio test (GLRT) and suggest a computationally efficient implementation thereof. Furthermore, we develop a new inexpensive detector for binary PSK signals, which we will refer to as the generalized energy detector. To evaluate the performance of these detectors, we attempt to derive a uniformly most powerful invariant (UMPI) test as an optimal detector. It turns out that the UMPI test exists only if the signal-to-noise ratio is known. We use this UMPI test in order to obtain an upper-bound performance for the evaluation of invariant detectors, such as the GLRT. Simulation results illustrate and compare the performance and the efficiency of the proposed signal activity detectors

Signal Activity Detection of Phase-Shift Keying Signals

We propose computationally inexpensive and efficient solutions for signal activity detection of phase-shift keying (PSK) signals in additive white Gaussian noise. We consider the complex amplitude of the signal as well as the information sequence as the unknown parameters. In addition, the noise variance is assumed unknown. We derive the generalized likelihood ratio test (GLRT) and suggest a computationally efficient implementation thereof. Furthermore, we develop a new inexpensive detector for binary PSK signals, which we will refer to as the generalized energy detector. To evaluate the performance of these detectors, we attempt to derive a uniformly most powerful invariant test (UMPI) as an optimal detector. It turns out that the UMPI test exists only if the signal-to-noise ratio is known. We use this UMPI test in order to obtain an upper-bound performance for the evaluation of invariant detectors, such as the above-mentioned GLRT. Simulation results illustrate and compare the performance and the efficiency of the proposed signal activity detectors.

New insights into optimal widely linear array receivers for the demodulation of BPSK, MSK, and GMSK signals corrupted by noncircular interferences-application to SAIC

For nonstationary observations, potentially second-order (SO) noncircular, the SO optimal complex filters are time variant and, under some conditions of noncircularity, widely linear (WL). For more than a decade, there has been an increasing interest in optimal WL filters in radiocommunications contexts involving rectilinear signals such as binary phase-shift keying (BPSK) signals. In particular, it has been pointed out that single antenna interference cancellation (SAIC) may be performed by such filters in the context of BPSK cellular networks. Recently, it has been shown that, by a simple algebraic operation of demodulation on the baseband signal, the minimum shift keying (MSK) and Gaussian MSK (GMSK) modulations can be made to approximately correspond to a BPSK modulation, allowing the application of the SAIC concept to the GSM cellular network at the mobile level, being currently studied for standardization, and offering significant improvements of the network's capacity. Despite the increasing interest in optimal WL filters in rectilinear or quasi-rectilinear contexts, many questions about their behavior and their performance have still arisen. The purpose of this paper is to gain insight into the behavior, properties, and performance of optimal WL array receivers, and thus of the SAIC technology, for the demodulation of BPSK, MSK, and GMSK signals corrupted by noncircular interferences.

BPSK to ASK Signal Conversion Using Injection-Locked Oscillators—Part I: Theory

This paper presents a new method and circuit for the conversion of binary phase-shift keying (BPSK) signals into amplitude shift keying signals. The basic principles of the conversion method are the superharmonic injection and locking of oscillator circuits, and interference phenomena. The first one is used to synchronize the oscillators, while the second is used to generate an amplitude interference pattern that reproduces the original phase modulation. When combined with an envelope detector, the proposed converter circuit allows the coherent demodulation of BPSK signals without need of any explicit carrier recovery system. The time response of the converter circuit to phase changes of the input signal, as well as the conversion limits, are discussed in detail.

Classification of BPSK and QPSK Signals Using an Antenna Array

We propose in this paper the use of a uniform linear array to improve the classification accuracy of two phase-shift keying (PSK) signals at different multiplicities, in particular, binary PSK (BPSK) and quadrature PSK (QPSK) signals. The proposed modulation classifier is based on the likelihood ratio test, where an additive white Gaussian noise with direct line-of-sight transmission is assumed. The likelihood functions of the two PSK signals depend on an unknown phase shift due to the signal arrival angle and the spatial separation of the antenna elements. A computationally efficient two-step processing is proposed to estimate the phase shifts to be used in the likelihood ratio test. The proposed phase shift estimation method reduces the computation significantly compared to the maximum likelihood solution, which requires numerical exhaustive search, and has an estimation accuracy reaching the Cram\'er-Rao lower bound at moderate signal-to-noise ratios. The proposed classifier improves the performance considerably compared to a single element receiver. Furthermore, the proposed classifier demodulates the transmitted symbol sequence in conjunction with the classification process, and no separate demodulation for the data symbol is needed after classification. Simulation results for BPSK and QPSK classification are provided.

Coherent Homodyne Detection of BPSK Signals Using Time-Gated Amplification and LiNbO&amp;lt;tex&amp;gt;$_3$&amp;lt;/tex&amp;gt;Optical 90&amp;lt;tex&amp;gt;$^circ$&amp;lt;/tex&amp;gt;Hybrid

We have investigated and compared the performance of coherent detection of 12.5-Gb/s nonreturn-to-zero and return-to-zero binary phase-shift keying (BPSK) signals using LiNbO/sub 3/ optical 90/spl deg/ hybrid with pulsed and continuous-wave local laser oscillator (LO). Our results showed that pulsed local oscillator provides at least 2-dB reduction in optical signal-to-noise ratio requirement. Increased eye opening and reduced bit-error ratio of the detected BPSK signal was observed using pulsed local oscillator. Pulsed local oscillator also provides pulse-shaping capability that reduces signal pulse-broadening penalty. Our simulation results agreed well with experiment and predicted that for a given signal and receiver bandwidth there is an optimal LO pulsewidth which gives maximum eye opening.

Optimal detection of a BPSK signal contaminated by interference and noise

The problem of detecting a desired binary phase-shift keying (BPSK) modulated bit in the presence of a second BPSK modulated interfering signal and additive white Gaussian noise is considered. Given knowledge of the amplitudes and phases of the unmodulated signals received from the two transmitters, the minimum achievable bit error rate is obtained and compared with that for a conventional matched filter detector. It is shown that the performance difference can be quite large when the interfering signal is strong.

Cramer-Rao bounds of SNR estimates for BPSK and QPSK modulated signals

We derive Cramer-Rao lower bounds (CRLBs) for the estimation of signal-to-noise ratio (SNR) of binary phase-shift keying (BPSK) and quaternary phase-shift keying (QPSK) modulated signals. The received signal is corrupted by additive white Gaussian noise (AWGN). The lower bounds are derived for non-data-aided estimation where the transmitted symbols are unknown at the receiver. The bounds are compared to those for data-aided estimations (known symbols at the receiver). It is shown that at low SNR there is a significant difference between the bounds for non-data-aided and data-aided estimations.

A subspace-based direction finding algorithm using fractional lower order statistics

We propose several classes of fractional lower order moment (FLOM)-based matrices that can be used with MUSIC to estimate the DOAs of independent circular signals embedded in additive S/spl alpha/S (symmetric /spl alpha/ stable) noise (e.g., sea clutter). We run simulations with different choices of the FLOM parameter p for our FLOM-based matrices and conclude that when the noise is S/spl alpha/S with unknown /spl alpha//spl ne/2, FLOM-multiple signal classification (MUSIC) with p close to unity yields good performance. The performance of FLOM-MUSIC and robust covariation-based (ROC)-MUSIC are similar. Three scenarios that contain circular signals (phase modulation (PM), circularly symmetrical Gaussian, and quaternary phase-shift keying (QPSK)) and one scenario that contains noncircular signals (binary phase-shift keying (BPSK)), all embedded in the same S/spl alpha/S noise, are tested. These simulation results reveal that the scenario containing BPSK signals leads to poor performance, indicating that FLOM-MUSIC is presently limited to circular signals.

Synthetic aperture sonar processing using wideband coded waveforms

Traditional narrow-band synthetic aperture sonar (SAS) suffers from reduced along-track resolution and reduced pulse repetition as the speed of the sonar platform increases. Wideband SAS systems offer a method for reducing these undesirable effects at the expense of increased system complexity. Most recently, Gough and Hayes have demonstrated the performance of a wideband SAS that uses continuous-tone frequency modulation (CTFM) as the transmitted waveform [J. Acoust. Soc. Am. 86 (1989)]. This paper presents the system design for a wideband SAS that uses binary phase-shift keyed (BPSK) modulation for the transmitted waveform. In addition to being wideband (like CTFM), the BPSK signal offers unique advantages over CTFM in active SAS systems. In the system presented here, maximal-length pseudo-random (or pseudo-noise, PN) sequences are used to encode the BPSK waveform, offering the ability to transmit uniquely different coded waveforms in rapid succession, hence providing a higher spatial sampling rate than is achievable with uncoded waveforms. In addition to the system design, computer simulations are presented that compare images generated by narrow-band, CTFM, and PN-BPSK processing. Tradeoffs between image quality versus processing complexity are discussed.

The capture effect in multiaccess communications-the Rayleigh and landmobile satellite channels

The capture phenomenon and its consequences in nonbitsynchronous mobile packet radio networks for binary phase-shift-keying (BPSK) and differential phase-shift-keying modulation are investigated. Exact values of the bit error probability for given signal-to-noise ratios of colliding BPSK signals are derived. Packet error rates, which are needed for analysis of slotted random multiple access methods, are obtained by simulation. Two kinds of mobile radio channels are considered: the Rayleigh fading channel and the land mobile satellite channel. In the latter, because of shadowing, the probability that one of several colliding data packets is correctly received can be on the same order as the probability that a single packet that is not experiencing a collision is correctly received. The influence of Reed-Solomon codes on packet error probabilities is also studied. A slotted ALOHA system using the land mobile satellite channel is analyzed. It is found that with significant shadowing, the overall system throughput may reach the point-to-point throughput. Also, the code rate cannot be optimized in a straightforward manner by assuming one single transmission at a time. >

Optical networking and signal-processing applications of 790 nm self-pulsating laser diodes

A series of investigations into the networking and signal-processing applications of 790 nm self-pulsating lasers is described. These devices, which were developed for optical disc interrogation, offer the response speed and power output expected of laser diodes but with substantially reduced coherence. This combination of properties is achieved by an appropriate cavity design which results in self-sustained, high-extinction-ratio oscillation at frequencies extending beyond 2 GHz. The resulting low-coherence emission substantially reduces modal noise in multimode fibre networks. Additionally, optoelectronic signal processing functions such as microwave injection-locking and carrier extraction are possible. We present two sets of experimental results. First, single-channel-per-laser subcarrier networking with respective aggregate throughputs of 450 Mbit/s and 1 Gbit/s over three binary phase shift keyed (BPSK) and five (quaternary phase shift keyed) QPSK channels is reported. Secondly, experimental observation of 1 GHz injection-locking together with 750 MHz and 1.5 GHz carrier extraction from BPSK and QPSK subcarrier signals centred on 375 MHz is described. Future applications for this work may be found in the areas of computer networking and optoelectronic signal-processing.