The current issue of the IETE Journal of Research (Vol.62, No.2, March–April 2016) contains 16 articles. These articles present on-going research and developments taking place in the broad areas of communication engineering. Specifically in this issue, the papers have been grouped in the area of signal processing, sensor networks, wireless communication and electromagnetics.
The paper ‘Speech recognition using ERB-like admissible wavelet packet decomposition based on perceptual sub-band weighting’, gives an equivalent rectangular bandwidth (ERB)-like wavelet filter for the determination of acoustic features for speech recognition applications. The computation of features based on auditory perception principles is useful in improving the robustness of speech recognition in the presence of noise. The efficacy of the features is demonstrated through noisy speech recognition performance studies, in various types of background noise.
The next paper on ‘Level crossing rate of macro-diversity system with two micro-diversity SC receivers over correlated gamma shadowed alpha-mu multipath fading channels’, is concerned with the study of two selection combining receivers operating in correlated multipath fading channels. Both short-term and long-term fading is considered. The cumulative density function of the receiver output signal envelope is derived as a numerical series. The level crossing rate that is a measure of second-order performance of wireless communication systems, is also numerically derived.
In the paper ‘Labelling of Hindi speech’, a method for syllable level labeling of Hindi speech based on group-delay based segmentation is given. The steps for finding the syllable boundaries is described. The accuracy of the labeling is studied with manually segmented speech utterances.
The paper titled ‘A novel order reduction approach for LTI systems using cuckoo search optimization and stability equation’, gives an approach for reducing the order of linear time invariant (LTI) systems based on meta-heuristic cuckoo search optimization and stability equation techniques. Both single-input single-output and multiple-input multiple-output LTI systems are addressed. The lower order system has the stability of the higher order system and matches the steady-state value. The method is compared with other model order reduction techniques through numerical examples.
In the paper ‘Analysis of the effect of binary OR operation property in linear network coding transmission performance’, the effect of using binary field (OR operation) property is analyzed for the purpose of generating the coding matrix elements instead of Galois field, for linear network coding. The LNC has been studied for multihop wireless network conditions for different topologies in terms of number of lost packets and packet delivery ratio measures.
The following paper on ‘Chaos-based image encryption using sum operation modulo 4 and 256’, presents an algorithm for encrypting color images using the chaotic logistic map and sum modulo operations. The encryption algorithm is studied for several images and compared with other algorithms. The algorithm is studied in terms of resistance to static and differential attacks.
The paper on ‘Channel allocation schemes for permanent user channel assignment in wireless cellular networks’, presents two models for permanent user channel assignment using Markov chain for wireless cellular networks. The models include channels for calling, handover, and permanent assignment. The blocking probability and handover failure probabilities are compared, and risk analysis to predict the blocked channels is given.
The next paper titled ‘Performance analysis for a touch dynamic authentication system with reduced feature set using neural networks’, examines the utility of touch dynamics as an additional layer of security for authentication. Thirty behavioral features from a user's swipe are used for this purpose. Neural networks are used with the feature set input to classify the users. Specifically, the Meta cognitive neural network, extreme learning machine, self-adaptive resource allocation network and minimal resource allocation network are examined in terms of accuracy of classification.
In the paper on ‘Collaborative spectrum sensing under primary user emulation attack in cognitive radio networks, the authors investigate a defense strategy of collaborative spectrum sensing in the event of primary user emulation attack (PUEA). A collaborative spectrum sensing method is given which is aware of spectrum holes and transmits the same power level that makes it difficult to differentiate between the received signal from a primary user and PUEA. The attack strength is estimated in terms of channel occupancy rate of the malicious PUEA in Neyman-Pearson or likelihood ratio test. The performance is studied through simulation experiments for probability of error vs. SNR.
The following paper on ‘Recursive sparsity-based MVDR algorithm for interference cancellation in sensor arrays’, gives an algorithm for beam forming using sparsity-based interference cancellation. The algorithm is compared with the minimum variance distortion less response algorithm. The sparsest array response in the angles other than the direction of arrival (DOA) of the signal of interest (SOI) is obtained. The global convergence of the algorithm is also investigated. The performance of the algorithm is studied in terms of side lobe levels, nulls, sensitivity to the DOA of the SOI, and sensitivity to data length.
The paper ‘New developments of characteristic analysis in wireless sensor networks’, gives the characteristic extraction methodology of wireless sensor networks. Various parameters are extracted from sensor information to determine the comprehensive nature of information characteristic of each sensor node. The information is useful in determining the utility of wireless sensor networks.
In the paper on ‘A novel sub-channel and power allocation in IEEE 802.16 OFDMA systems’, a resource allocation method for IEEE 802.16 OFDMA systems is given. Classically, a power allocation algorithm is an iterative algorithm with long convergence time. Power and sub channel allocation schemes are considered in two-dimensional frame. The resource allocation complexity is addressed by using an adaptive step size that is derived, in the iterative optimal Lagrange multiplier computation. The performance is studied through simulations in terms of throughput and maximum sum rate as a function of the number of users.
The following paper on ‘Influence of ASE noise on the performance of DWDM networks using low-powered pumped Raman amplifiers’, presents the study of the effect of amplified spontaneous emission (ASE) noise, noise figure, and dispersion chromatic on dense-wavelength-division-multiplexing (DWDM) networks based on low-power pumped distributed Raman amplifiers (DRA). Two different pumping configurations, forward and backward, are considered. Simulation studies of bit error rate (BER), NF, ASE noise powers are studied using OptiSystem 7 software to explain the utility of DWDM transmission networks.
The paper on ‘A software multi-GNSS receiver implementation for the Indian Regional Navigation Satellite System’, presents the results of the IRNSS receiver implementation in Finland. The paper describes the receiver architecture that includes the acquisition and tracking stages and position computation. It is shown that multi-GNSS positioning, even with a system intended outside the service area of IRNSS, can be useful by augmenting other satellite systems over north and east Europe.
The following paper titled, ‘A -10 dBm 5 Mbps energy-efficient injection-locked FSK transceiver for wireless body sensor networks’, gives a low-energy data transmission technique that is studied on a 915 MHz 5 Mbps injection-locked FSK RF transceiver. The utility of this study is in different blocks of sensor nodes used with a wireless transceiver. The performance is studied in post layout simulation results that show a reduction in power consumption in transmitter mode compared to other reported studies.
The next paper titled ‘A new low-power, high-Q, wide tunable CMOS active inductor for RF applications’, gives a topology for realizing single-ended inductor with a few number of passive components. The quality factor is found for 1700 MHz frequency. The design and simulation of the active inductor is given for 90-nm process and the current consumption, effective area, noise voltage are given.