Double Overt-Leaf Shaped CPW-Fed Four Port UWB MIMO Antenna

This paper presents a 4 × 4 multi-input multi-output antenna array for ultra-wideband applications. The single element of the array is comprised of a modified co-planar waveguide-fed double overt-leaf shaped patch radiator. The co-planar ground is optimized to achieve maximum impedance matching in the operating frequency band. The results show that the single antenna element offers an impedance bandwidth of 13.2 GHz starting from 3.2 GHz to 16.7 GHz. It is also observed from the results that the antenna offers good radiation characteristics and acceptable gain for the frequency band of interest. Furthermore, a 4 × 4 MIMO array is designed by utilizing the polarization diversity technique. To improve the isolation performance among antenna elements, a fan-shaped decoupler is introduced on the other side of the substrate, which ensures minimum isolation of 20 dB. Moreover, the proposed MIMO array operates in the frequency range of 2.75–16.05 GHz. The proposed MIMO array is fabricated and measured for the validation of simulation results, and it is observed that both the results are well in agreement.

Proximity Measurement for Hierarchical Categorical Attributes in Big Data

Nearly most of the organizations store massive amounts of data in large databases for research, statistics, and mining purposes. In most cases, much of the accumulated data contain sensitive information belonging to individuals which may breach privacy. Hence, ensuring privacy in big data is considered a very important issue. The concept of privacy aims to protect sensitive information from various attacks that may violate the identity of individuals. Anonymization techniques are considered the best way to ensure privacy in big data. Various works have been already realized, taking into account horizontal clustering. The L-diversity technique is one of those techniques dealing with sensitive numerical and categorical attributes. However, the majority of anonymization techniques using L-diversity principle for hierarchical data cannot resist the similarity attack and therefore cannot ensure privacy carefully. In order to prevent the similarity attack while preserving data utility, a hybrid technique dealing with categorical attributes is proposed in this paper. Furthermore, we highlighted all the steps of our proposed algorithm with detailed comments. Moreover, the algorithm is implemented and evaluated according to a well-known information loss-based criterion which is Normalized Certainty Penalty (NCP). The obtained results show a good balance between privacy and data utility.

Research and Development of a Transportable Optical Ground Station in NICT: The Results of the First Performance Test

In recent years, the necessity of free-space optical (FSO) communications has increased as a method for realizing high-speed communications between satellites and the ground. However, one disadvantage of FSO communications is the significant influence of the atmosphere. Specifically, FSO communications cannot be utilized under certain atmospheric conditions, especially in the presence of clouds. One of the solutions to this problem is the site diversity technique, which makes it possible to select a given ground station with better atmospheric conditions among a number of fixed ground stations. The other solution is to prepare a ground station that can be moved to a place with better atmospheric conditions. We applied the latter method and developed a transportable optical ground station in NICT. We utilize a realistic telescope diameter, which is about 30 cm at the maximum, capable of being set up quickly, and with a pointing accuracy of about 100 µrad. In addition, it is necessary to prepare a fine-pointing optical system that performs tracking with about 1/10 of the pointing accuracy of the telescope. In this paper, we report the results of the first performance test of the transportable optical ground station in NICT.

ANALISIS IMPLEMENTASI FREQUENCY DIVERSITY TERHADAP NILAI AVAILABILITY SYSTEM PADA WILAYAH URBAN DAN RURAL

The widely used transmission media, one of which is transmission media using microwave. Microwaves are still needed today as not all locations allow for network performances using cables, in addition to the influence of small natural disasters, and are more practical to implement in urban and rural areas. But in the use of micro wave transmission there are constraints that can cause the transmission process to experience interference in the process of conveying information. One obstacle that affects transmission of radio waves is the presence of fading effect that causes the decline in the receiving power and damage transmission quality. Therefore, the optimization process is necessary to increase the availability of the microwave communication system. The use of a diversity technique can increase the value of system reliability. In this research the diversity technique used is frequency diversity. The result of the design simulation of microwave transmission network in this study obtained the value of system reliability before using the diversity technique of 99.99348%. Whereas after using frequency diversity technique obtained the result of 99.99934%. The final result of this simulation is as expected by the application of frequency diversity technique will optimize service to users with a system reliability level of 0.00586% more optimal.