Mustafa M. Matalgah

Performance analysis of IPSec protocol: encryption and authentication

IPSec provides two types of security algorithms, symmetric encryption algorithms (e.g. data encryption standard DES) for encryption, and one-way hash functions (e.g., message digest MD5 and secured hash algorithm SHA1) for authentication. This paper presents performance analysis and comparisons between these algorithms in terms of time complexity and space complexity. Parameters considered are processing power and input size. The analysis results revealed that HMAC-MD5 can be sufficient for the authentication purposes rather than using the more complicated HMAC-SHA1 algorithm. In encryption applications, authentication should be combined with DES.

Moment generating function of the generalized α - μ distribution with applications

In this letter, we consider the alpha - mu channel fading model and we evaluate the moment generating function (MGF) for the probability density function characterizing this new channel model. The derived MGF expression is used in evaluating the bit error rate for different coherent modulation techniques over this generalized fading channel. We also derive an expression for the outage probability for this channel model. All the derived expressions are in closed forms and general that can reduce to the well known fading channel distributions in the literature such as Rayleigh, Nakagami-m, and Weibull model as special cases.

The wavelet transform and its applications to phonocardiogram signal analysis.

The wavelet transform, which is the decomposition of a signal into a set of independent frequency channels, is shown to be a useful diagnostic tool in the analysis of heartbeat sounds. In particular, the wavelet transform enables the experimentalist to obtain qualitative and quantitative measurements of time-frequency characteristics of phonocardiogram (PCG) signals.

Performance of dual maximal ratio combining diversity in nonidentical correlated Weibull fading channels using Pade/spl acute/ approximation

In this letter, we evaluate the performance of the dual-branch maximal ratio combining (MRC) diversity scheme in nonidentical correlated Weibull fading channels with arbitrary parameters. We first use the Pade/spl acute/ approximation (PA) to find closed-form rational expressions for the moment generating function (MGF) of the output signal-to-noise ratio (SNR) of the MRC receiver. Different performance measures, such as the outage probability and the average symbol-error rate for different linear modulations, are then presented using the well-known MGF approach. Furthermore, the effect of the input SNRs unbalancing, the severity of fading, and the degree of correlation on the system performance are also studied. Our results are validated by comparing them with computer simulations, and we show that the PA technique is indeed a convenient tool for such performance evaluation studies.

Performance of the short-time Fourier Transform and Wavelet Transform to phonocardiogram signal analysis

In this paper the shortages of using the Nan&ml Fourier Transform to analyze the Phonocardiogram (KG) signals is first pointed out and the need for time-varyingdigitat signal processing techniquesto conectly analyzeKG signals is discussed.‘I%vo timefrequency analysis techniques am presented in this pape~ namely, the Spectrogram and the Wavelet Transform. Furthermore, a comparisonstudy between these two techniques has shown the ~lution diffenmces between them. The Wavelet Transform is shown to be capable to detect the two components, aortic valve component A2 and pulmonary valve compment P2, of the second sound S2 of a normal PCG signal which am not detectable neitherusing the standardFourier‘fkansfonnmr the Spectrogram.In addition to thz the Wavelet ‘fYansfomtenables Physicians to obtain qualitative and quantitative measurements of time-fiwpency characteristicsof phonocadiogram (KG) signals.

Hybrid frequency-polarization shift-keying Modulation for optical transmission

In this paper, we propose a new modulation scheme based on combining frequency and polarization modulated signals, which we will refer to as hybrid frequency-polarization shift keying (FPolSK). The FPolSK modulation is basically an extension of the conventional M-PolSK modulation over orthogonal domains. This expansion enables representing signal constellation points over multidimensional space, which ensures increasing the geometric distances between these points, and in turn, improving the system power efficiency. On the other hand, compared with M-FSK modulation, FPolSK improves the bandwidth efficiency by employing less number of orthogonal frequencies to represent information symbols. Moreover, FPolSK is extremely useful for implementing communication systems that have limitations in power and bandwidth usage. This advantage comes from the fact that FPolSK inherently enables selecting the appropriate number of orthogonal frequencies that convey with system constraints. The contribution in this paper is threefold. First, we propose a design for the transmitter and the receiver of the FPolSK technique. Second, we perform analysis for the system power and bandwidth efficiencies. Third, we derive an expression for the system power spectral density (PSD). A performance comparison between the FPolSK modulation technique and previously developed techniques is also presented in this paper. Our results reveal that the proposed modulation scheme performs better than M-PolSK, M-DPSK, and M-FSK modulation schemes in terms of both power and bandwidth efficiencies. We have also found that same bandwidth efficiency can be obtained using different FPolSK modulation formats, and the PSD of the FPolSK modulation does not contain discrete components that are considered as a waste of power. Finally, the effects of the laser phase noise and fiber dispersion on the performance of the proposed modulation are also discussed in detail.

On the use of padé approximation for performance evaluation of maximal ratio combining diversity over Weibull fading channels

We use the Padé approximation (PA) technique to obtain closed-form approximate expressions for the moment-generating function (MGF) of the Weibull random variable. Unlike previously obtained closed-form exact expressions for the MGF, which are relatively complicated as being given in terms of the Meijer G-function, PA can be used to obtain simple rational expressions for the MGF, which can be easily used in further computations. We illustrate the accuracy of the PA technique by comparing its results to either the existing exact MGF or to that obtained via Monte Carlo simulations. Using the approximate expressions, we analyze the performance of digital modulation schemes over the single channel and the multichannels employing maximal ratio combining (MRC) under the Weibull fading assumption. Our results show excellent agreement with previously published results as well as with simulations.

Modified-DES encryption algorithm with improved BER performance in wireless communication

Due to the fact that wireless channels are an open medium to intruders and their attacks, encryption is a vital process to assure security over these channels. However, using well-known encryption algorithms to encrypt data in wireless communication will result in a catastrophic error due to the avalanche effect, which is implemented in these algorithms to assure security. Although this effect is desirable to assure security, these algorithms do not take into account the bit error characteristics of the wireless channel. Therefore, if an error occurs in the encrypted data over the channel, the decryption process at the receiver will result in half the original bits to be in error due to the avalanche effect. So the need for a new secure encryption algorithm that takes into account the bit error characteristics of wireless channels becomes necessary. In this paper, we propose a modification to the Data Encryption Standard (DES) to make it secure and prone to the bit errors caused by the wireless channel. We observe that using the modified algorithm in wireless channels, improves the bit error rate (BER) performance as well as security compared to DES.

Fast method for precoding and decoding of distributive multi-input multi-output channels in relay-based decode-and-forward cooperative wireless networks

It is well-known that the performance of the relay-based decode-and-forward (DF) cooperative networks outperforms the performance of the amplify-and-forward cooperative networks. However, this performance improvement is accomplished at the expense of adding more signal processing complexity (precoding/decoding) at each relay node. In this study, the authors tackle this signal processing complexity issue by proposing a Jacket-based fast method for reducing the precoding/decoding complexity in terms of time computation. Jacket transforms have shown to find applications in signal processing and coding theory. Jacket transforms are defined to be n × n matrices A =( a jk ) over a field F with the property AA ? = nI n , where A ? is the transpose matrix of the element-wise inverse of A , that is, A ? =( a kj -1 ), which generalise Hadamard transforms and centre weighted Hadamard transforms. In particular, exploiting the Jacket transform properties, the authors propose a new eigenvalue decomposition (EVD) method with application in precoding and decoding of distributive multi-input multi-output channels in relay-based DF cooperative wireless networks in which the transmission is based on using single-symbol decodable space-time block codes. The authors show that the proposed Jacket-based method of EVD has significant reduction in its computational time as compared to the conventional-based EVD method. Performance in terms of computational time reduction is evaluated quantitatively through mathematical analysis and numerical results.

Channel characteristics of the generalized alpha-mu multipath fading model

In this paper, we consider a relatively new small scale multipath fading model, namely; the α−μ fading distribution. We derive expressions for the amount of fading and the average channel capacity for this channel model and show the generalized attribute of this fading model. The obtained expressions for the performance metrics reduce to other expressions for other channel models as special cases. Numerical results for the obtained expressions are provided and some conclusions are also drawn.