A review article of multi-band, multi-mode microstrip filters for RF, WLAN, WiMAX, and wireless communication by using stepped impedance resonator (SIR)

Filters are the basic part in wired, and wireless telecommunications and radar system circuits and they play an important role in determining the cost and performance of a system. The increasing demand for high performance in the fields of RF, WLAN, WiMAX and other wireless communications led to the great revolution in the advancement of the development of a compact microstrip resonator filter design. All these have made a vital contribution to both the required performance specifications for filters and other commercial requirements in terms of low cost, large storage capacity and high-speed performance. This review paper presents several design examples for multi-band, multi - mode microstrip filter resonators to satisfy RF, WLAN, WiMAX, UWB and other wireless communication frequency bands. To analyse the resonant frequencies odd - mode and even -modes can be used for the symmetrical structure. In general, the multi-mode resonators can be designed by using different methods like cross-coupling resonators Structure, and the allocation of the fundamental resonant frequencies of the resonator as stated by the Chebyshev's insertion loss function

Impacts of IoT and big data to automotive industry

With the recent advancement in technologies such as embedded system, wireless distributed sensor, light weight material, smart cognitive radio networks, cloud computing, higher efficiency and ultra-low emission internal combustion engines, intelligent converter, high performance battery and fuel cell technology, the production of smarter, safer, energy efficient and zero emission vehicles is possible in near future. Apart from vehicle technologies, other factors such as road users', well maintained road infrastructure, well maintained vehicles, drivers' attitudes and law and enforcement are also important to be considered and they should work together in order to make our world natural resources can be preserved and maintain cleaner environment and produce sustainable mobility. This paper will discuss the impacts of IoT and Big Data and other emerging technologies mentioned above to the automotive industry. It will include discussion on education, economy, advanced technology, environment, safety and energy

Performance evaluation of an efficient RZ-MQAM modulation scheme in all-optical OFDM transmission systems

All optical orthogonal frequency division multiplexing (AO-OFDM) technique is a promising technique and employed in many military applications for data transmission over long distance. But AO-OFDM signals are very sensitive to nonlinear distortion and these systems suffer from nonlinear impairments. This paper describes a novel nonlinear phase noise reduction technique by decreasing interaction time between subcarriers in AO-OFDM transmission systems. This technique mitigates the effects of nonlinearity on all-optical OFDM transmission systems and improves performance of transmission systems. The proposed AO-OFDM transmission system has been successfully simulated and analyzed for estimating phase noise due to cross-phase modulation, self-phase modulation and four-wave mixing. The proposed RZ-8QAM AO-OFDM system with 29 subcarriers is examined and the transmission distance is fixed at 550km

Development of a pulse-width modulated power MOSFET-based audio amplifier

This paper presents the design and development of a pulse-width-modulated (PWM) power MOSFET-based audio amplifier. A natural sampled PWM switching strategy is implemented in the development of the amplifier to reduce its harmonic level and increase its efficiency. IRF510 power MOSFETs are used as the amplifier power switching devices. From the results obtained, it is found that the efficiency of the amplifier can be increased to more than 90%

Performance comparison of indoor VLC system employing SAC-OCDMA technique

Performance comparison of indoor visible light communication (VLC) system with spectral amplitude coding-optical code division multiple access (SAC-OCDMA) techniques using Khazani-Syed (KS) code is examined. Bit error rate (BER) of three different codes was investigated in terms of background optical noise interference in the system. The result shows that KS code offers a slightly better performance under the influence of ambient light noise interference with a lower code length, a few number of filters and lower BER

Analysis of AC - to - DC uncontrolled converters harmonics for electric vehicles applications

This paper discusses the harmonic analysis of the AC-to-DC uncontrolled converters commonly used in electric vehicles charging station. The aim of this paper is to model and simulate different rectifier models in addition to explaining the differences in input current harmonics, the total Harmonic Distortion (THD) as well as the power factor (pf). The converter configurations include single-phase bridge, 6-pulse and 12-pulse rectifier circuits. The single phase is normally used for electric scooter charging, while three-phase converters can be used for both electric bus and car charging. The circuit configurations of the rectifiers were modelled and simulated using Matlab R2014a to achieve the objective of the study. The results revealed that the THD levels were extremely high which is unacceptable if the system is connected to the utility grid

Using curve-fitting optimisation technique to estimate power MOSFET model parameters for PECT II system

This paper presents a proposed new structure of the power MOSFET model and its implementation in the HSPICE and PECT II (Power Electronics and Control Tool) packages. A fast and accurate technique for determining power MOSFET model parameters which introduces a curve-fitting optimisation technique is discussed in detail. The optimisation process generates automatically a set of device parameters based on the input specification, measured data and manufacturer's data sheets. The input procedure involves a netlist specifying parameter tolerances, component voltage and current limits and an initial guess to the selected parameter. Using curve fitting and iterative methods, the "correct" model is generated for utilisation in the simulation phase of both the HSPICE and PECT II packages. This method is then compared to that of a normal method which uses specific formulae to obtain power MOSFET model parameters. The results show that the curve-fitting optimisation technique produces more accurate power MOSFET model parameters than the other method. Both simulation and experimental results of the power MOSFET characteristics are also included in the discussion

New call blocking probability (NCBP) in improved adaptive quality of service (AdQoS) for wireless multimedia communications using hierarchical cellular approach

The maintenance of quality of service (QoS) in a wireless environment is a difficult problem. Most researchers have already acknowledged adaptive techniques as the appropriate method to deal with the fluctuation of QoS in a wireless cellular network. This paper proposes an improved new call blocking probability (NCBP) from an adaptive QoS (AdQoS) to support the QoS guarantee. Besides using an adaptive technique, this method utilizes a hierarchical cellular approach with a bandwidth reallocation algorithm to determine the acceptance or rejection of a new call. The approach would improve the NCBP performance of the multimedia application over high-speed wireless cellular networks

Investigation of circulation noise effect on SAC-OCDMA system with ring topology

In this paper, we investigate the performance of an OCDMA system with ring topology where number of the spans can be more than one. Effect of circulation noise is evaluated beside of shot noise and thermal noise. Through analytical approach, it is shown that higher amount of amplifier gain, produces higher amount of circulation noise. Also by increasing the number of nodes, the strength of the circulation noise is reduced and the ratio of this reduction is more for lower amplifier gain. For example, with increasing number of the nodes from 3 to 8, the amount of log variance of circulation noise increases only 1 unit (-13 to -14) for amplifier gain 20 dBm, while this value is 4 units (from -15 to -19) if gain is 10 dBm

Stabilization of decision threshold for BER improvement using double carrier modulation/differential detection for outdoor optical wireless communications

A new transmission and detection technique namely Double Carrier Modulation/Differential Detection (DCM/Diff.D) for outdoor optical wireless (OW) is proposed. The technique employs two beams, one modulated with the data, the other with the inverted version of the same data. A differential detection technique is used at the receiver whereby the inverted data are used as the reference to perform the decision making, as opposed to the fixed threshold used in conventional technique. The probability of error under threshold instability in DCM/Diff.D technique and Intensity Modulation/Direct Detection (IM/DD) technique, is compared. A simulation under heavy rainfall condition of 8.33x10-4 cm/sec at bit rate of 2.5 Gbps with 0 dBm of optical transmitter power shows that this technique achieves an improvement of more then twice of distance of the conventional IM/DD