Two dimensional switched beam antenna based on cascaded butler matrix beamforming network

This paper presents a low cost, two dimensional (2-D) millimetre wave switched-beam array antenna attained by feeding a planar array antenna with a cascaded 4 x 4 Butler matrix (BM) beam forming network (BFN). To minimise the surface current, ensure low cost and ease fabrication, a single layer has been implemented. The prototype is fabricated and measured results presented. According to the results, the maximum beam scanning of from -41ᵒ to +42ᵒ, and a maximum antenna gain of 13.8 dBi are obtained in the x-z plane. While the maximum beam scanning of from -43ᵒ to +41ᵒ and the maximum antenna gain of 13.7 dBi are realized in the y-z plane. With a single pole multiple throw switches, switching the various matrix terminals on the BM in the horizontal plane gives the beams in the x-z plane, while switching the BM in the vertical plane gives the beams in the y-z plane. All experimental and numerical results are in good agreement which can be practically used for fifth generation (5G) wireless systems.Keywords: Cascaded Butler matrix, Beamforming Network, switched-beam antenna, 5

Switched-beam array antenna at 28 GHz for 5G wireless system based on butler matrix beamforming network

This work presents a compact, switched-beam array antenna on 4 × 4 Butler Matrix (BM) beamforming network (BFN) at 28 GHz for fifth generation (5G) wireless system. A single layer has been chosen to ensure low cost and ease fabrication. The four input ports of the designed antenna have the capability of producing four independent directional beam patterns at 13.8°, -43.5°, 44° and -14°, when P1, P2, P3 and P4, respectively are excited. The radiation efficiency obtained from each of the four ports is well above 80% at the designated frequency. The peak antenna gain of 15.9 dBi is obtained at port 1 and 4. The design is verified by measurement and all results have a good correlation with simulation.Keywords: Array antenna, Butler matrix, millimetre wave, switched-beam antenna, 5

Time-Scale Domain Characterization of Time-Varying Ultrawideband Infostation Channel

The time-scale domain geometrical-based method for the characterization of the time varying ultrawideband (UWB) channel typical of an infostation channel is presented. Compared to methods that use Doppler shift as a measure of time-variation in the channel this model provides a more reliable measure of frequency dispersion caused by terminal mobility in the UWB infostation channel. Particularly, it offers carrier frequency independent method of computing wideband channel responses and parameters which are important for ultrawideband systems. Results show that the frequency dispersion of the channel depends on the frequency and not on the choice of bandwidth. And time dispersion depends on bandwidth and not on the frequency. It is also shown that for time-varying UWB, frame length defined over the coherence time obtained with reference to the carrier frequency results in an error margin which can be reduced by using the coherence time defined with respect to the maximum frequency in a given frequency band. And the estimation of the frequency offset using the time-scale domain (wideband) model presented here (especially in the case of multiband UWB frequency synchronization) is more accurate than using frequency offset estimate obtained from narrowband models

A Software Radio Design Approach for Heterogeneous Wireless Access Protocol Transceivers

A study on the design of heterogeneous transceivers using the software radio approach is presented. The objective of the study is to extend the research on software radio towards the design of multi-protocol transceivers which can communicate between two or more heterogeneous wireless access technologies. A critical overview of some of the current multi- protocol software radio devices is presented. This is then followed by a proposal for a dual band WiFi/WiMAX transceiver based on software radio techniques. This design incorporates a multiband antenna as well as an RF WiFi/WiMAX mode switch which uses the WiFi received signal strength (RSS) to perform handover between the underlying WiFi and WiMAX networks

A Prospective Cohort Study on IRS Gene Polymorphisms in Type 2 Diabetes Mellitus Patients during Severe/Acute Hyperglycemia Phase 1: Association with Insulin Resistance

Purpose: To investigate the genetic polymorphisms that may contribute to the worsening of insulin resistance in type 2 diabetes mellitus (T2DM) with severe or acute hyperglycemia.Methods: This is a prospective cohort study involving 156 T2DM patients with severe or acute hyperglycemia from all medical wards of the National University of Malaysia Medical Centre (UKMMC) that were placed on insulin therapy. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to determine the genetic association of insulin receptor substrate (IRS) gene with insulin resistance. Insulin resistance status was determined using the homeostatic model assessment for insulin resistance (HOMA-IR) index.Results: IRS1 polymorphisms were associated with increased insulin resistance (X2 = 5.09, p = 0.023) in T2DM patients with severe/acute hyperglycemia. IRS2 polymorphisms were not associated with insulin resistance (X2 = 0.69, p = 0.406) in this group of patients.Conclusion: IRS1 genetic factor alone may be a significant genetic determinant for insulin resistance in T2DM patients during severe/acute phase hyperglycemia.Keywords: Insulin receptor substrate, Genetic, Polymorphism, Diabetes, Insulin resistance, Hyperglycemia, IRS1, IRS

Design LTE microstrip antenna rectangular patch with beetle-shaped slot

In this paper, the microstrip antenna rectangular patch with beetle shaped slot is presented. The characterization results of the proposed antenna obtained by changing the dimensions of the ground plane. CST software is used to design and analyze this proposed antenna. The simulated results of proposed antenna show that the antenna works at the frequency of 2.1 GHz while the return loss of -32.18 dB with the bandwidth reaches 155.19 MHz and the gain of 3.895 dBi

Device discovery for D2D communication in in-band cellular networks using sphere decoder like (SDL) algorithm

In the fifth generation (5G), it is anticipated that device-to-device (D2D) operation will be locally incorporated as a part without any bounds. In D2D network, multiple devices coexisting is a challenging subject of device discovery. The device discovery is performed under a visually impaired situation such as channel information, location, and the number of devices. In this paper, centralized device discovery is chosen due to power consumption and signaling overhead of the distributed system. A distinctive approach for device discovery in an in-band cellular network, based on the device’s power, is suggested with an efficient technique which enhances the implementation of D2D communication and improves the accomplishment by alleviating the discovery issues. The group of devices forms a lattice structure, and it is positioned in the coverage area. The hypersphere is constructed based on the power knowledge of a discoverer device which helps for accurate and fast device discovery in a lattice structure. Besides, sphere decoder like (SDL) algorithm is applied for quick and precise discovery in the lattice structure. Simulation results present the performance of the proposed QR factorized lattice structure scheme regarding device power, enhanced in the number of discovered devices and controlled signaling overhead

Segmentation Of Stretched Pap Smear Cytology Images Using Clustering Algorithm.

Papanicolaou test or better known as Pap test is the most popular and effective screening test for cervical cancer. At time, however, the detection of abnormal or cancerous cervical cells can be missed due to technical and human errors

Fatty acids composition of microalgae Chlorella vulgaris can be modulated by varying carbon dioxide concentration in outdoor culture

Varying culture methods of Chlorella vulgaris (CV) has been associated with different nutrient composition. The aim of this study was to investigate the fatty acid contents and other nutrients of CV subjected to various culturing conditions. We found that CV cultured under 24 h light and 10% CO2 showed the best growth rates and contained higher lipid, protein and moisture contents compared to other culture conditions. Interestingly, the content of fatty acids of CV was dependent on the amount of CO2. Fatty acid analysis of CV by gas chromatography-mass spectrometry (GC-MS) showed the presence of cis-10-pentadecanoic acid (C15:1), palmitic acid (C16:0), palmitoleic acid (C16:1), heptadecanoic acid (C17:0), stearic acid (C18:0), oleic acid (C18:1n9c), linoleic acid (C18:2n6c), linolenic acids (C18:3n3) and arachidic acid (C20:0). Remarkably, polyunsaturated fatty acids (linoleic and linolenic acids) are found in abundance compared to other fatty acids in CV. The concentrations of palmitic, oleic, linoleic and linolenic acids increased when the amount of carbon dioxide was raised from 1 to 10% under both culture conditions (12 and 24 h light). This study shows the possibility of modifying lipid contents in freshwater microalgae by varying the amount of carbon dioxide and light.Key words: Chlorella vulgaris, microalgae, fatty acids, vitamins, minerals, carbon dioxide

Swarm optimization based radio resource allocation for dense devices D2D communication

In Device to Device (D2D) communication two or more devices communicate directly with each other in the in-band cellular network. It enhances the spectral efficiency due to cellular radio resources (RR) are shared among the cellular users and D2D users. If the RR sharing is not legitimate properly, it causes interference and inefficient use. Therefore, management of RR between cellular users and D2D users is required to control the interference and inefficient use of RR. In D2D enabled cellular network, D2D users have a good signal to noise ratio (SNR) compared with cellular users due to the short distances and dedicated path. Using this advantage, an efficient RR allocation algorithm based on swarm optimization is proposed in this paper, that allows utmost spatial reuse in multi-users and OFDMA networks. The algorithm determines the required RR on the request of D2D users following the indicator variable. It enhances the capacity (Bit/Hz), overall system throughput and spectral efficiency with respect to sub-carriers in OFDMA networks. The performance of the proposed algorithm is evaluated via MATLAB simulations