1.562 Gb/s phase-encrypted secure communication

Wireless data transmission with binary phase-shift keying modulation encoded on a 92 GHz carrier is achieved using photonic components. A high-speed photodiode is used to convert the doubly-modulated optical signal to a modulated millimeter-wave carrier. A W-band Mach-Zehnder interferometer with a one-bit time delay is used to directly detect the differential phase-shift keyed millimeter-wave wireless signal without the use of a local oscillator. Field tests with antennas separated by 890 m demonstrate the ability to discriminate two phase states for differential binary phase shift keying (DBPSK) and four phase states for differential quadrature phase shift keying (DQPSK) at data rates of 2.3 Gb/s and 4.6 Gb/s, respectively.

In this paper, we analyze the end-to-end (e2e) performance of a millimeter-wave (mmWave) multi-hop relay network. The relays in it are decode-and-forward (DF) type. As appropriate for mmWave bands, we incorporate path loss and blockages considering the links to be either line of sight (LOS) or non line of sight (NLOS). The links also experience Nakagami-m fading with different m-parameters for the LOS and NLOS states. We consider two scenarios, namely sparse and dense deployments. In the sparse case, the nodes (relays and the destination) are limited by additive noise only. We derive closed-form expressions for the distribution of equivalent e2e signal-to-noise-ratio (SNR), coverage probability, ergodic capacity, and symbol error rate (SER) for the three classes of digital modulation schemes, namely, binary phase shift keying (BPSK), differential BPSK (DBPSK), and square-quadrature amplitude modulation (QAM). In the dense case, the nodes are limited by interference only. Here, we consider two situations: 1) interference powers are independent and identically distributed (i.i.d.) and 2) they are independent but not identically distributed (i.n.i.d.). For the latter situation, closed-form analysis is exceedingly difficult. Therefore, we use the Welch-Satterthwaite Approximation for the sum of Gamma variables to derive the distribution of the total interference. For both situations, we derive the distribution of signal-to-interference ratio (SIR), coverage probability, ergodic capacity, and SERs for the DBPSK and BPSK. We study how these measures are affected by the number of hops. The accuracy of the analytical results is verified via Monte-Carlo simulation. We show that multi-hop relaying provides significant coverage improvements in blockage-prone mmWave networks.

In the present work, simple closed-form series solutions for the average error rate of several coherent modulation schemes such as, binary phase shift keying (BPSK), binary frequency shift keying (BFSK), differential binary phase shift keying (DBPSK), quadrature phase shift keying (QPSK), offset-QPSK, minimum shift keying (MSK), and square M-ary quadrature amplitude modulation (M-QAM), operating over frequency non-selective slow Rician fading channel and corrupted by additive white Gaussian noise (AWGN) are derived. Further, to improve the link quality, receiver antenna space diversity is considered, where multiple independent and identically distributed (i.i.d.) as well as uncorrelated signal replicas are combined before successive demodulation. The proposed linear predetection combiner follows optimum maximal ratio combining (MRC) algorithm. Starting from a novel unified expression of conditional error probability the error rates are analysed using probability density function (pdf) based approach. The derived end expressions, consisting of rapidly converging infinite series summations of Gauss hypergeometric function, are accurate, free from any numerical integration and general enough, as it encompasses as special situations, some cases of non-diversity, non-fading AWGN and Rayleigh fading. Symbol or, bit error probabilities (SEP/BEP) are graphically displayed against signal to noise ratio (SNR) per bit per channel for all the digital modulation schemes stated above with different values of diversity order L and varying values of the channel specular-to-scatter ratio or, the Rician parameter K, as found from the measured statistics of mobile and indoor wireless channels. In addition, to examine the dependence of error rate performance of M-QAM on the constellation size M, numerical results are plotted for various values of M. Selected simulation results are also provided to verify the analytical deductions. The series solutions presented in current text realize a trade-off between precision and complexity and offers valuable insight into the performance evaluation over a fading channel in a unified manner.

A unified approach is presented for evaluation of the error probabilities of a class of digital communications systems in additive noise and interference. This class of systems includes coherent systems such as M -ary amplitude-shift keying (ASK), M -ary phase-shift keying (PSK), and M -ary amplitude-and-phase keying (APK); it also includes differential coherent systems such as binary differential PSK (DPSK). The noise is not necessarily Gaussian. The interference can be intersymbol interference, co-channel interference, adjacent-channel interference, any of their linear combinations, or intermodulation prodducts at the output of some nonlinear device. This approach essentially expands the characteristic function of the interferences into a power series so that the desired error probability can be evaluated as the sum of terms representing perturbations around the error probability due to additive noise alone. Bounds on three kinds of truncation errors, which are simple and applicable to all aforementioned digital systems, are obtained. As a result, any desired accuracy in the evaluation of the error probabilities can be achieved with this approach. In the special case in which the noise is Gaussian, explicit bounds on truncation errors are also obtained. Examples are given to illustrate how the unified analysis can be applied to evaluate the error probabilities of various digital systems. More specifically, the combined effects of Gaussian noise, intersymbol interference, and co-channel interference on the error performance of M -ary coherent PSK and APK (MCPSK and MCAPK) systems are computed. The probability of error of a binary DPSK (BDPSK) system in the presence of Gaussian noise and intersymbol interference is analyzed. The intermodulation products at the output of a hardlimiter are also determined.

We propose a novel multi-dimensional optical transmission system based on a direct detection system. In the proposed system, quadrature phase shift keying (QPSK), binary polarized intensity rotational frequency shift keying (PIRBFSK), and binary differential phase shift keying (DBPSK) signals modulated by optical intensity, polarization, and phase are simultaneously transmitted for optical multi-dimensional transmission. The signal transmission performance of the proposed modulation technique and the possible interference of each dimension modulation were numerically and experimentally analyzed. The performance of the proposed system was verified using the bit error rate (BER), eye diagram, and spectrum of the received multi-dimensional signal.

We propose an iterative decoding scheme for low density parity check codes concatenated with binary differential phase shift keying (BDPSK) in additive white Gaussian channels with unknown phase offset by viewing the BDPSK modulator as the encoder of a rate-one convolutional code. To assist this iterative scheme, a new log-likelihood ratio (LLR) metric based on three consecutive received symbols is derived. This metric takes a priori information of other coded bits into account and therefore applicable to the proposed iterative scheme. We show that the proposed iterative scheme has better performance than systems using other LLR metrics for noncoherent detections. The performance of the proposed scheme under signal-to-noise ratio estimation error is also investigated.

In this paper, the average bit error rate (ABER) performance of binary coherent and non-coherent modulation is investigated over a new fading channel which is well known as Beaulieu-Xie fading channel. This fading model consists of multiple no. of line-of-sight (LOS) components with some diffuse power. Specifically, the closed-form expressions are derived for the exact ABER of binary phase-shift keying (BPSK) and differential phase-shift keying (DPSK) by using the probability density function (PDF) approach. The final exact expression for BPSK is obtained in the form of infinite series which needs a reasonable number of terms to converge and the final expression for DPSK is expressed in terms of elementary functions. It is observed that ABER decreases with increase in specular power and/or with decrease in fading severity. The obtained results are applied to general scenarios for various values of fading parameters by adjusting the specular power and fading severity. The numerical results plotted by using the derived expressions show a close agreement with the results obtained by Monte Carlo simulation.

A multi-tone code division multiple access (MT-CDMA) system with post-detection diversity combining is analyzed. The analysis is presented in terms of average bit error rate (BER). The modulator uses differential quadrature phase shift keying (DQPSK) signaling over a slowly Rician fading and frequency selective channel in the indoor environment. Here, the influence of the order of diversity and number of tones is studied for given bandwidth (BW), bit rate and transmitter power. The paper also compares the BER performance between differential binary phase shift keying (DBPSK) and DQPSK based MT-CDMA systems.

This paper presents recent progress toward the realization of ultrahigh-speed coherent optical transmission with a single-channel bit rate of more than 1 Tbit/s using ultrashort pulse technology and an advanced modulation format. We first describe Tbit/s optical time-division multiplexing (OTDM) transmission employing differential binary or quadrature phase shift keying. We present our recent demonstrations of single-polarization 640-Gb/s differential phase-shift keying and 1.28-Tb/s differential quadrature phase-shift keying transmissions over 525 km, which employ an ultrafast optical Fourier transformation technique. We then focus on coherent optical transmission using quadrature amplitude modulation (QAM) with a multiplicity of 512 that enables us to achieve an ultrahigh spectral efficiency of more than 10 b/s/Hz. Finally, we demonstrate a novel ultrahigh-speed, spectrally efficient coherent pulse transmission combining OTDM and QAM. A 400 Gb/s, 32 RZ/QAM signal was successfully transmitted over 225 km on a single carrier at 10 Gsymbol/s × 4-OTDM.

Multiple-input multiple-output (MIMO) systems employing both maximal-ratio transmission and receive antenna selection (MRT&RAS) are studied in this paper. The examination has been done for independent and identically distributed (i.i.d.) flat Nakagami-m fading channels. Exact bit error rate (BER) expressions for binary phase shift keying (BPSK), differential binary phase shift keying (DBPSK) and binary frequency shift keying (BFSK) signals are derived by using the moment generating function (MGF)-based analysis method. By deriving upper bounds for exact BER expressions, it is shown that the investigated systems achieve full diversity orders at high signal-to-noise ratios (SNRs). Also, the ergodic system capacity and outage probability of MRT&RAS scheme have been analyzed. Exact BER results for different system and channel conditions are validated by Monte Carlo simulations.

This paper has demonstrated the simulation study of the high speed dense wavelength division multiplexing (DWDM) transceiver optical communication system based hybrid FSO/OFC channel for local area network applications. The modulation techniques are employed such as coherent binary frequency shift keying (CBFSK), coherent binary phase shift keying (CBPSK), noncoherent binary frequency shift keying (NBFSK), and differential binary phase shift keying (DBPSK). The spectral channel losses and the spectral channel dispersion are demonstrated versus the spectral operating wavelengths and FSO/OFC communication channel based on different modulation technique with the optimum network reach. Output modulated power and maximum Q factor are clarified against various amplification techniques and the spectral operating wavelengths for both FSO and OFC communication channel based on DBPSK modulation technique with the optimum network reach. Optimum output modulated power and optimum signal per noise ratio (signal quality) are studied and simulated in relation to overall network reach based FSO/OFC communication channel with DBPSK modulation technique and EDFA–Raman–EDFA amplification technique.

This paper addresses Differential Binary Phase Shift Keying (DBPSK) modulation implemented on SDR platform for the development of digital data communications based on SDR. DBPSK modulation performance perceived at Packet Error Rate (PER) is evaluated in terms of Eb/No or S/N ratio, carrier frequency, bit rate, gain, roll-off factor of root Nyquist filter or root raised cosine filter, and of size of payload from delivered data. Based on this results, the smallest PER could be obtained by setting Eb/No value which is greater than 13 dB, carrier frequency of at least 0,3 MHz, optimum bit rate of 256 kbps, optimum range payload size of 2000 up to 4000 bytes, and roll-off factor of Nyquist or root-raised cosine filter of 0.1<alfa<0.9.

In this paper, we present a low-complexity low data rate (LDR) ultra wideband (UWB) transceiver prototype CMOS chip suitable for a differential binary phase shift keying (DBPSK) modulation applied data transmission with 500 MHz-bandwidth signals. This solution, which is mainly based on "1.5-bit" direct sub-sampling at 1 Gsps and differential digital correlations, enjoys good immunity to clock drift and interferers. It is also likely to offer an interesting trade-off between fine performance in dense multipath environments, low implementation complexity, and hence low power consumption. At first, the 1.5 bits concept is discussed. Then, the implementation choices for some critical blocks of the RX data path are discussed to justify the adopted low-complexity approach. Finally, some preliminary implementation results are provided.

Evaluating the performance of the cooperative communications using the hardware testbed in the real environment is critical for system design and promoting the potential practical applications in the future, considering the disadvantages of the theoretical analysis and simulation methods. In this paper, a distributed hardware testbed using software-defined radios is designed and implemented for cooperative communications, and the performance of two coded cooperation schemes with Turbo codes is evaluated in the physical layer. For the testbed, the fundamental point-to-point link uses the differential binary phase shift keying (DBPSK) constellations, and the physical (PHY)/media access (MAC) layer frames for the performance evaluation are devised. Furthermore, a distributed node synchronization scheme is implemented and the source node and relay node work in the time division protocol without any centralized controlling. Finally, two popular coded cooperation schemes with Turbo codes for the three-node model and the four-node model are tested in the real indoor environment. The experiment results verify the effectiveness of the testbed for system performance evaluation in the PHY layer.

Power line communication (PLC) utilizes power lines for the purpose of electronic data transmission. Differential binary phase shift keying (DBPSK) is a popular modulation scheme proposed in the PLC standards like G3, PRIME, and IEEE P1901.2. This letter provides the performance evaluation of a PLC system assuming DBPSK modulation under the combined effect of Nakagami- $m$ background noise and impulsive noise. We utilize a simple, yet accurate approximation available in literature to derive the probability density function of the sum of two Nakagami- $m$ random variables. Closed-form expressions of the analytical average bit error rate and the outage probability of the system are derived. Validity of the derived analytical expressions is closely verified by simulated results.