Phase Shift Keying Modulation Scheme Research Articles

Frequency Offset Invariant Multiple Symbol Differential Detection of MPSK

Multiple-symbol differential detection (MSDD) of differentially encoded phase-shift keying (PSK) signals in the presence of random frequency variation and additive white Gaussian noise is studied. It is shown that frequency variation distorts the transmitted signal through attenuating its amplitude and introducing a time-varying phase shift to the information symbols. A double differential PSK (DDPSK) modulation scheme is then introduced and a MSDD for detecting DDPSK signals in the presence of frequency offset is proposed. It is shown that the proposed receiver is robust to the distortions caused by the random frequency variation. A lower bound on the error probability of the proposed MSDD receiver is also derived and compared to that of an autocorrelation demodulator for the case where the observation interval approaches infinity.

A reconfigurable software defined ultra-wideband impulse radio transceiver

Abstract. An ultra-wideband (UWB) software defined radio (SDR) implementation is presented. The developed impulse radio (IR) transceiver employs first order bandpass (BP) sampling at a conversion frequency which is four times the channel bandwidth. The subsampling architecture directly provides the RF signal avoiding any non-ideal mixer stages and reduces the requirements of digital signal processing implemented in a field programmable gate array (FPGA). The transmitter consists basically of a multi-Nyquist digital to analog converter (DAC), whereas the implemented matched filter (MF) receiver prototype employs a standard digitizing oscilloscope. This design can be adaptively reconfigured in terms of modulation, data rate, and channel equalization. The reconfigurable design is used for an extensive performance analysis of the quadrature phase shift keying (QPSK) modulation scheme investigating the influence of different antennas, amplifiers, narrowband interferers as well as different equalizer lengths. Even for distances up to 7 m in a multipath environment robust communication was achieved.

Error Probability Analysis of Bidirectional Relay Systems Using Alamouti Scheme

We consider a bidirectional relay system using a physical-layer network coding (PNC) protocol with Alamouti's space-time block coding (STBC) at the two source nodes while there is only one antenna at the relay node. Upper and lower bounds on symbol error probability (SEP) are derived for Binary Phase Shift Keying (BPSK) modulation scheme. It is shown that a diversity order of 2 can be achieved even that the relay node has only a single antenna. Simulation results are provided to confirm our analysis for the SEP.

Effect of Microdiversity and Macrodiversity on Average Bit Error Probability in Gamma-Shadowed Rician Fading Channels

In this letter, we analyze the error performance of a mobile communication system with microdiversity and macrodiversity reception in gamma-shadowed Rician fading channels for a binary differential phase-shift keying modulation scheme. Analytical expressions for the probability density function (PDF) and moment-generating function (MGF) are derived. The average bit error probability can be calculated by averaging the conditional bit error probability over the PDF or using the MGF-based approach. Numerical results are graphically presented to show the effects of macrodiversity, correlation, number of diversity branches, and severity of both fading and shadowing.

Symbol Error Performance Analysis and Comparison Between Alamouti and MRRC Diversity Combining Scheme for Wireless Communication

The symbol error performance of a wireless communication system is analyzed using diversity combining scheme in Rayleigh fading channels. The performance of the system is compared using Alamouti scheme and maximal-ratio receiver combining (MRRC) scheme. The performance results of the system are evaluated by numerical computation and by simulation using MATLAB. A detailed analysis and exact (closed-form) expressions of the probability of error of the wireless communication systems in Rayleigh fading channels are provided for both M-ary phase-shift keying (M-PSK) and M-ary quadrature amplitude modulation (M-QAM) schemes. Monte Carlo simulation shows exact match with the theoretical results. Keywords: Alamouti scheme; M-PSK; M-QAM; MRRC; Symbol error probability (SEP). © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v2i1.3000 J. Sci. Res. 2 (1), 54-66 (2010)

Performance Analysis of Different Phase Shift Keying Modulation Schemes in Aeronautical Channels

This paper undertakes the performance evaluation and comparison of different phase shift keying (PSK) modulation schemes in aeronautical channels. Specifically, bit error rate (BER) curves and outage probabilities of various modulation schemes in high dynamic environments are investigated by means of numerical analysis and computer simulation. Simulation results show that the performance of all modulation schemes degrades with the increase of the power ratio or dynamic factor, and that differential quadrature phase shift keying (DQPSK), differential 8 phase shift keying (D8PSK), 16 and 64 differential amplitude and phase shift keying (DAPSK) perform better than other same order modulation schemes, respectively. As the conclusion, the differential modulation schemes are more suitable for the aeronautical channels in order to withstand the Doppler shift and the changing rate of the Doppler.

A Broadband Power-Line Communication System Design Scheme for Typical Tanzanian Low-Voltage Network

Information and communications technologies (ICTs) are gaining importance in developing countries. Power-line network is a potential infrastructure for ICT services provision. Power-lines are highly interconnected network with stochastic variation in number of branches. Under such distributed network conditions the design of a broadband power-line communication (BPLC) system is a challenge. In this paper a case study of an actual power-line network, representative of a low-voltage BPLC channel in Dar es Salaam, Tanzania is considered. We shall investigate the performance of such a low-voltage channel that uses orthogonal frequency division multiplexing (OFDM) technique with binary phase shift keying (BPSK) modulation scheme for communication. For sensitivity analysis, three different transmitter locations were chosen and receiver points were varied to identify the possible degraded performance scenarios. Analysis show that in the frequency bands of 100 MHz, the channel delay spread for such networks is about 4 mus, giving a maximum number of subchannels 4096 with 512 cyclic prefix. To improve the degraded performance scenarios, the concatenated Reed Solomon outer code with punctured convolution inner code was applied to the network. It was found that when the branches were terminated by its corresponding characteristic impedances the performance is improved by 10-20 dB compared to a corresponding uncoded system. On the contrary for a coded system when the branches were terminated either in low or higher impedances compared to branch characteristic impedances the improvement was greater than 2-15 dB. This study demonstrates that the specification proposed by IEEE-802.16 broadband wireless access working groups can be used for performance improvement of distributed low-voltage systems.

위상 파라미터 도출을 통한 H-MPSK의 BER 성능 분석

계층적 M진 위상 편이 변조(hierarchical M-ary phase shift keying) 방식은 설정된 위상 파라미터에 따라 각 비트의 오류 성능이 변하기 때문에 각 시스템의 요구에 맞은 위상 파라미터 값을 구할 수 있는 방법을 필요로 한다. 따라서 본 논문에서는 계층적 M-PSK 변조 방식에 대한 BER의 근사적 접근을 통해 원하는 각 비트의 오류 성능에 따라 중요 위상 파라미터를 찾을 수 있는 방법을 제안하고, 이전에 제시된 계층적 M-PSK 변조 방식에 대한 정확한 오류 성능 분석 방법을 통하여 제안한 방법의 정당성을 검증한다. Bit error rate(BER) performance of each bit for hierarchical M-ary phase shift keying(H-MPSK) modulation scheme is changed according to the phase parameters. Thus, a method to find the phase parameters appropriate to the requests of the system is needed. In this paper, we propose a method to obtain the phase parameters from an approximate approach of BER for H-MPSK and verify a validity of the proposed method through the previously provided expression for analyzing an exact error probability of H-MPSK.

Quadrature Amplitude Modulation for Differential Space-Time Block Codes

Differential Space-Time Block Codes (DSTBC) do not require any radio channel measurement and channel state information neither on the transmitter nor at the receiver side. Therefore, they are an attractive alternative to coherent Multiple-Input Multiple-output (MIMO) systems. The classical technical proposal for differential techniques is based on M-ary phase shift keying (M-PSK) modulation schemes for DSTBC (PSK-DSTBC). One advantage of this scheme is the constant envelop of the transmit signal, but it is well known that higher-order PSK is less efficient due to the small distance between adjacent points in the constellation diagram. Therefore, in this paper an alternative modulation technique for DSTBC is discussed, which is based on quadrature amplitude modulation (QAM-DSTBC). The signal envelope of the transmit signal is not any more constant in this case. Therefore, the technical challenge of integrating QAM into the DSTBC system design is to control the transmit power in order to avoid an increase or a decrease in transmit power to some extreme values. The mechanism, which is used in this paper to control the transmit power is based on an extension of the original QAM constellation diagram. The additional points, which are integrated into the constellation diagram are used in this case for the mapping procedure to select one of the modulation symbols with high or alternatively low signal power. This means for each single bit pattern there are almost always two modulation symbols available in the mapping procedure one with low and one with high signal power, which gives the basis for a signal power control algorithm. The resulting bit-error-rate (BER) performance of QAM-DSTBC is compared finally to the performance figures of the original proposal of PSK-DSTBC.

A minimum approximate-BER beamforming approach for PSK modulated wireless systems

A beamforming algorithm is introduced based on the general objective function that approximates the bit error rate for the wireless systems with binary phase shift keying and quadrature phase shift keying modulation schemes. The proposed minimum approximate bit error rate (ABER) beamforming approach does not rely on the Gaussian assumption of the channel noise. Therefore, this approach is also applicable when the channel noise is non-Gaussian. The simulation results show that the proposed minimum ABER solution improves the standard minimum mean squares error beamforming solution, in terms of a smaller achievable system’s bit error rate.

Fully complex-valued radial basis function networks: Orthogonal least squares regression and classification

We consider a fully complex-valued radial basis function (RBF) network for regression and classification applications. For regression problems, the locally regularised orthogonal least squares (LROLS) algorithm aided with the D-optimality experimental design, originally derived for constructing parsimonious real-valued RBF models, is extended to the fully complex-valued RBF (CVRBF) network. Like its real-valued counterpart, the proposed algorithm aims to achieve maximised model robustness and sparsity by combining two effective and complementary approaches. The LROLS algorithm alone is capable of producing a very parsimonious model with excellent generalisation performance while the D-optimality design criterion further enhances the model efficiency and robustness. By specifying an appropriate weighting for the D-optimality cost in the combined model selecting criterion, the entire model construction procedure becomes automatic. An example of identifying a complex-valued nonlinear channel is used to illustrate the regression application of the proposed fully CVRBF network. The proposed fully CVRBF network is also applied to four-class classification problems that are typically encountered in communication systems. A complex-valued orthogonal forward selection algorithm based on the multi-class Fisher ratio of class separability measure is derived for constructing sparse CVRBF classifiers that generalise well. The effectiveness of the proposed algorithm is demonstrated using the example of nonlinear beamforming for multiple-antenna aided communication systems that employ complex-valued quadrature phase shift keying modulation scheme.

高度ＢＳデジタル放送用ＬＤＰＣ符号の設計

We have been studying an advanced satellite broadcasting system which is aimed at improving the Integrated Services Digital Broadcasting for Satellite (ISDB-S) system. By making use of LDPC codes and the reduced roll-off factor, this advanced system can increase its transmission channel capacity to 30% that of the ISDB-S one. Furthermore, by applying multi-level amplitude phase shift keying (M-APSK) modulation schemes, we can increase the transmission channel capacity. We report on LDPC codes that are designed for the transmission format of the advanced satellite broadcasting system. The computer simulation results of B/Q/8PSK performances under the AWGN channel model are also reported. We also discuss and report the optimization result gained from a computer simulation of the radius ratio of LDPC-coded 16APSK and 32APSK modulation, which is proposed in this advanced system, with respect to Bit Error Rate (BER) under the AWGN channel model.

Coded Single-Sideband QPSK and Its Turbo Detection for Mobile Communication Systems

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper proposes a novel single-sideband quadrature phase shift keying (SSB QPSK) modulation scheme that utilizes a single-reference carrier frequency and transforms both baseband I and Q components into the same radio frequency band, whose width is exactly half that of QPSK. The modulation method is first derived and followed by the analysis of the matched filter demodulation. The analysis shows that there are performance degradations due to intersymbol interference (ISI) in the received signal and correlation in the received noise. To suppress the degradations, this paper employs a turbo equalizer for demodulation, in which the effects of ISI and noise correlation can be suppressed by a soft canceler and a noise whitening filter in the minimum mean square error (MMSE) linear equalizer, respectively. The computer simulations are then used to verify the proposed modulation scheme. At the transmitter, the root-raised cosine rolloff filter is employed for pulse shaping and Hilbert-transformed pulse generation. The truncation of the signal pulse is performed by the window function. The results show that the proposed modulation scheme outperforms 16-quadratic-amplitude modulation (16-QAM) with the turbo code in the Rayleigh-fading environment. </para>

Performance analysis of equal-gain diversity receivers over generalized Gamma fading channels

Generalized Gamma (GG) distribution is a generic model that covers many well-known fading distributions as special cases. This paper deals with the performance analysis of L-branch equal gain combining (EGC) receivers operating over GG fading channels. For these receivers and by using convergent infinite series approach, the probability of error ( P e ) can be formulated in the form of an infinite series. The coefficients of P e series can be derived by calculating complicated integrations over the fading envelope distribution. In this paper, it is shown that the required integrations for the case of GG distribution have a complex closed-form in terms of Meijer's G function, and then, a new approximation method is developed for computation of them. The proposed method only needs mean and variance of the fading envelope; hence it has low complexity and eliminates the need for calculation of complex functions. The presented numerical examples show that the developed method can approximate the required parameters and also the individual coefficients accurately and this accuracy increases with the increase of L. The proposed method is applied to analyze the probability of error performance of the L-branch EGC receiver with both coherent phase shift keying (CPSK) and frequency shift keying (CFSK) modulation schemes under different GG channel conditions. Also the effect of gain unbalance between diversity branches on the probability of error is investigated.

Performance Analysis of SC DS-CDMA and MC DS-CDMA Systems over Nakagami-m Fading Channel

This paper deals with simulation of Nakagami-m fading in wireless channels using generalized SC DS-CDMA and MC DS-CDMA schemes using binary phase shift keying modulation scheme. The paper proposes for deriving Bit Error Rate (BER) in BPSK-SC DSCDMA and MC DS-CDMA systems over Nakagami-m fading channels. The numerical results are plotted as BER vs SNR for various values of Nakagami factor m, number of users K and jamming interference (JSR) using MAT LAB software. The performance of Nakagami-m channel using BPSK-SC DS-CDMA and MC DS-CDMA techniques are compared. It is observed that there is a decrease in Bit Error Rate for increase in m for SC DS-CDMA and MC DS-CDMA. The number of users k, JSR increases as Bit Error Rate increases for MC DSCDMA. For the same values of m BER for MC DS-CDMA is smaller when compared with SC DS-CDMA using Maximal Ratio Combining (MRC) diversity technique.

Space–time decision feedback equalisation using a minimum bit error rate design for single-input multiple-output channels

A minimum bit error rate (MBER) decision feedback equaliser (DFE) designed for single-input multiple-output (SIMO) systems employing a quadrature phase shift keying (QPSK) modulation scheme is proposed. It is shown that this MBER design is superior over the standard minimum mean square error DFE in the SIMO scenario considered, in terms of the achievable system bit error rate. A sample-by-sample adaptive implementation of this MBER DFE is derived, which is referred to as the least bit error rate (LBER) algorithm. It is shown that for SIMO systems using a QPSK scheme, the LBER algorithm has a similar computational complexity as the simple least mean square (LMS) algorithm. Simulation results demonstrate that the proposed adaptive LBER-based DFE outperforms the adaptive LMS-based DFE, in both stationary and fading cases.

Antenna aperture averaging with different modulation schemes for optical satellite communication links

The performance of the optical satellite communication links is degraded in atmospheric environment. The degradation is more in the case of an on-off keying (OOK) modulation scheme. The antenna aperture averaging method is used to improve system performance for different modulation schemes. With this method, it is found that improvement in system performance employing OOK modulation is higher as compared to subcarrier binary phase-shift keying and subcarrier quadrature phase-shift keying modulation schemes.

Design of Amplitude and Phase Modulated Signals for Differential Space-Time Block Codes

A differential space-time block code (DSTBC) provides full diversity advantage and does not require any radio channel estimation in the receiver, which makes it an attractive alternative to the well-known coherent space-time block code (STBC). However the original design of DSTBC allows only pure phase shift keying (M-PSK) modulation scheme, which are not optimal for M > 4. In this paper a simultaneous amplitude and phase modulation scheme for DSTBC with 2 transmit and several receive antennas is introduced. The performance of the proposed scheme is investigated and compared with DSTBC techniques using pure M-PSK modulation.

Optically Based Direct Sequence Binary Phase Shift Keying Modulation Scheme for Indoor Ultrawide-Band Wireless Systems

In this study, we focus on the design of an optical-based ultrawide-band (UWB) transmission system with a direct sequence-binary phase shift keying (DS-BPSK) modulation scheme for indoor wireless communication environments. The distinct pseudorandom noise (PN) code sequences are assigned to users that share a channel in the UWB multiple-access system. Filtered second-order Gaussian monocycle pulses can provide large bandwidths for very high-speed communications. Moreover, fiber dispersion and intersymbol interference (ISI) problems can be avoided by properly adjusting pulse width. The simulation and analytical results demonstrate that the presented scheme indeed provides several GHz bandwidths for future indoor UWB wireless applications.

Performance of Space-Time Block Coding in Powerline and Satellite Communications

In this paper Space-Time Block Coding (STBC) is examined in powerline and satellite communications, comparing the gains that this coding-modulation technique provides to these communications systems. The powerline environment is assumed to be a frequency-selective, multipath fading environment with Additive White Class A Noise (AWCN), which is used to model the actual powerline noise characteristics. The satellite channel for urban area, modeled as a combination of Rayleigh and log-normal processes with the presence of Additive White Gaussian Noise (AWGN) is also studied. System efficiency is enhanced by the application of Orthogonal Frequency Division Multiplexing (OFDM), convolutional coding and block interleaving and the performance of different Phase Shift Keying (PSK) modulation schemes under the imposed channel conditions is investigated. The performance of the system is assessed by the commonly used Bit Error Rate (BER) vs. Signal to Noise Ratio (SNR) diagrams and there is also a comparison regarding the throughput efficiency among the examined systems. As stated in the results section, STBC can be used in powerline and satellite communications providing remarkable results, comparable to those in terrestrial wireless communications where STBC is nowadays a rather mature technique