The current issue of the IETE Journal of Research (Vol.60, No.4, July-August 2014) contains 7 articles. These articles present on-going research and developments taking place in the broad areas of Communication Engineering, Electrical Engineering, Electromagnetics, Computer Science and Engineering and Microelectronics.
The paper on “A Hybrid Scheme for Wireless Physical Layer Security based on Encryption and Channel Pre-Compensation,” proposes a hybrid scheme for providing wireless physical layer security by combining cryptography and physical layer characteristics. The physical layer security is provided by converting the signal constellation into a higher order constellation by using conventional encryption (symmetric key encryption) and then using channel state information (i.e. amplitude and phase variation), which is location specific, to further encrypt the constellation before transmission. It has been shown that the hybrid scheme provides security in wireless environment resulting in high BER at the eavesdropper.
The next paper on “A Scene Based Video Watermarking Using Slant Transform,” gives a robust video watermarking that is based on slant transform. The video is partitioned into frames and owner's identity watermark is embedded in slant transform domain by modifying the transform coefficients. It has been shown that the transparency of the watermarked image is enhanced by embedding the watermark in selected positions based on the human visual system (HVS) weightage matrix. The robustness of the proposed algorithm has been examined by subjecting the algorithm to various compressional and signal processing attacks. The weights of robust locations are computed based on quantization matrix that exploits the HVS characteristics. It has been shown that the watermarks embedded in middle frequency bands provide a trade-off between imperceptibility and robustness.
In the paper “An Enhanced Inter-domain Mobile Protocol for IPv6-based Wireless Networks” the authors propose an enhanced inter-domain mobile protocol for IPv6-based wireless networks. In this architecture, a wireless network is made up of multiple global domains, and a global domain consists of multiple local domains. The proposed inter-domain mobility algorithm reduces the handover delay and lower the packet loss. In the algorithm, the L2 handover and the L3 handover are performed in parallel, so the handover delay is shortened.
The paper entitled “Comparative SAR Analysis of Some Indian Fruits as per the Revised RF Exposure Guideline” presents data on RF power absorption level in terms of SAR evaluation of some native fruits as per the revised Indian RF exposure guideline, particularly in GSM 900 and GSM 1800 MHz bands along with Wi-Fi 2400 MHz band at public exposure zone. The observations show that quiet high power is absorbed within the fruits especially for GSM 1800 and Wi-Fi 2400 MHz frequency bands which may cause some possible hazards in the growth of the fruits and plants. The authors have suggested further exhaustive investigations to be carried out.
In the next paper “Four-Step Iterative Design Optimization Technique for DLHL IMPATTs," the authors have proposed four-step iterative optimization technique to design a double low-high-low (DLHL) impact avalanche transit time (IMPATT) diode on Si for 60 GHz operation. Initially the position of the charge bumps in both n- and p-epitaxial layers followed by the widths of those and the ratio of high to low doping concentrations have been varied to obtain the maximum large-signal DC to radio frequency (RF) conversion efficiency from the device. Finally the bias current density is varied within a specified range to obtain the optimum value of it for which the DC to RF conversion efficiency of the device is maximum. The optimized DLHL diode is capable of delivering significantly higher RF power output with greater DC to RF conversion efficiency at 60 GHz as compared to its un-optimized counterpart.
The paper entitled “Constrained Optimum Design of 3-DOF Micro-accelerometers” presents a technique to optimize with constraints, the performance of three degrees of freedom silicon accelerometers. A flexure configuration has been proposed in order to meet the requirements of small cross-axial acceleration, high sensitivity, and linear sensitivity. The authors claim that the 3-DOF micro-accelerometers designed with the proposed optimization technique can be implemented without difficulty. One important characteristic of this optimized sensor is the low power consumption.
The last paper on “Using SVC to Economically Improve Transient Stability in Long Transmission Lines” aims to select optimal size, location, and parameter setting of static var compensator (SVC) to improve power system stability in long transmission lines. MOPSO technique is used to determine the optimal location, size, and controller parameter setting of SVC. The effectiveness of the proposed method to improve the transient stability and reduce the investment cost of SVC has been shown. A test system with two machines is used to demonstrate the effectiveness of the proposed MOPSO-optimized size, location, and controller parameter setting.