Prestasi dan perlaksanaan kawalan kuasa untuk sistem W-CDMA

Pa >aran perhubungan bersel telah berkembang secara raendadak pada beberapa tahun kebelakangan ini. Matlamat utama sistem perhubungan bersel ini adalah untuk menyediakan perkhidmatan perhubungan tanpa perlu memilih masa dan tempat. Teknologi antaramuka udara ' Wideband Code Division Multiple Access' ataupun secara ringkas W-CDMA telah dipilih untuk kebanyakan pengendali perkhidmatan perhubungan bersel di dalam merealisasikan perlaksanaan sistem perhubungan bersel generasi baru ini. Sistem W-CDMA diharapkan sebagai langkah pertama ke arah sistem bersel digit Generasi Ketiga. Salah satu daripada pengurusan sumber-sumber radio W-CDMA yang kritikal ialah kawalan kuasa. Tanpa kehadiran kawalan kuasa, kesan fenomena gangguan hujung-dekat-hujung-jauh menjadi perusa dan muatan sistem bergerak W-CDMA adalah sangat rendah. Takrifan kawalan kuasa yang baik adalah penting untuk sistem W-CDMA berfungsi dengan betul dan membolehkan pengguna-pengguna untuk berkongsi sumber-sumber sistem W-CDMA secara bersama di antara mereka. Tambahan lagi, dengan kawalan kuasa yang betul membolehkan jumlah penghantaran kuasa sistem bergerak dikurangkan kepada tahap minimum supaya tiada kuasa berlebihan yang diperlukan telah disinarkan dan melanjutkan hayat bated. Disertasi ini adalah hasil kajian ke atas prestasi algoritma kawalan kuasa sistem W-CDMA melalui simulasi komputer yang telah dibangunkan. Kesan perubahan beberapa parameter masukan terhadap mutu dan muatan sistem telah dianalisis berdasarkan beberapa andaian. Dua algoritma kawalan kuasa yang berlainan juga dibandingkan untuk menentukan prestasi algoritma yang menghasilkan keputusan yang lebih baik. Keputusan simulasi menunjukkan bahawa kawalan kuasa berupaya mengatasi masalah pemudaran isyarat dan gangguan hujung-dekat-hujung�jauh dengan menghasilkan tahap gangguan yang minimum bagi semua pengguna. Algoritma DSSPC (Dynamic Step Size Power Control) menunjukkan prestasi yang lebih baik berbanding algoritma FSSPC {Fixed Step Size Power Control) berdasarkan kepada keputusan simulasi yang telah dilakukan

Inverted Diamond-shaped Notched Substrate and Patch for High-frequency Interference on Ultra-wideband Antenna

Notches loaded on a patch antenna can affect significantly on ‎the antenna impedance matching. Therefore, notching technique is an efficient way to reduce ‎the electromagnetic interference with unwanted bands. In this paper, a ‎novel inverted diamond‏-‏shaped closed-end slot on a substrate and ‎vertex-fed printed hexagonal patch ultra‏-‏wideband antenna is proposed for high-frequency band rejection. This antenna is fed using ‎coplanar waveguide, and it is optimised by veering several patch ‎parameters which further improved the inter bandwidth at both the ‎lower and upper bands. However, the centre-notched band is shifted ‎from 6 GHz to 7.5 GHz by cutting the inverted diamond shape in a ‎special process. The developed ultra-wideband antenna is verified by ‎comparing the simulation results with the measurement results. The ‎measured results with a fractional bandwidth of 133% have a good ‎agreement with the simulation results 146%. Moreover, the measured radiation showed omnidirectional patterns‎

Zero-Padding techniques in OFDM systems

Although the OFDM system has been gaining importance in recent years, the high peak to average power ratio is considered the main limitation of the system. The oversampling operation in the frequency-domain plays an essential role in the PAPR calculations precisely. The main purpose of the paper to draw attention to zero-padding methods which are used to oversampled baseband OFDM signals. Moreover, to study the influence of the zero-padding methods on the accuracy of the PAPR calculations, and the spectral spreading of the OFDM signals. Simulation results show that the zero-padding method which inserts the zeros at the center of the baseband OFDM signal is better than the other zero-padding methods in terms of both accuracy PAPR calculations and spectral distributio

A New Subblock Segmentation Scheme in Partial Transmit Sequence for Reducing PAPR Value in OFDM Systems

Partial transmit sequence (PTS) is considered an efficient algorithm to alleviate the high peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. The PTS technique is depended on the partitioning the input data sequence into the several subblocks, and then weighting these subblocks with a group of the phase factors. There are three common types of partitioning schemes: interleaving scheme (IL-PTS), adjacent scheme (Ad-PTS), and pseudo-random scheme (PR-PTS). The three conventional partitioning schemes have various performances of the PAPR value and the computational complexity pattern which are considered the main problems of the OFDM system. In this paper, the three ordinary partition schemes are analyzed and discussed depending on the capability of reducing the PAPR value and the computational complexity. Furthermore, new partitioning scheme is introduced in order to improve the PAPR reduction performance. The simulation results indicated that the PR-PTS scheme could achieve the superiority in PAPR mitigation compared with the rest of the schemes at the expense of increasing the computational complexity. Furthermore, the new segmentation scheme improved the PAPR reduction performance better than that the Ad-PTS and IL-PTS schemes

Symmetrical couple f-shaped notches with high rejection c-band of uwb patch antenna

The ultra-wideband (UWB) antenna is developed to cover a broad bandwidth. ‎The UWB radio systems are interfered ‎by the ‎same ‎spectrum ‎that shared with the local bands. In this paper, two F-shaped slots on a hexagonal patch UWB antenna are demonstrated ‎‎ to realize a high band rejection. The symmetrical couple F-slots is ‎notched on the hexagonal UWB ‎ ‎patch antenna to avoid the interference ‎and ‎‎enhance the notching results at C-band. The demonstrated ‎antenna employs a coplanar waveguide ‎(CPW) technique to meet a fractional bandwidth of 126%. The proposed method validates ‎several ‎‎reconfigurations of the F-slot location on the demonstrated design. Six steps ‎parametric study are considered to test the slots location. The results of the proposed antenna with slots are introduced based on analytical, simulation, and ‎measurement. The total design size ‎‎28 mm × 43 mm × 1.6 ‎mm is simulated by ‎using CST Microwave Studio. The two F-slots are achieved the antenna gain of -6 dB, ‎return loss of -1.2 ‎dB, and ‎VSWR of 15.2 at the rejected band of 4 GHz. The ‎measurement results are compared with the simulation results between the three ‎prototypes. The current ‎distribution on the design is discussed at 2.88 GHz and 4 GHz frequencies. The radiation patterns illustrate ‎omnidirectional of H-plane and bidirectional of E-plane. This paper validates the slots locations to enhance the notches performance and reduce the interference

IoT Based Health Monitoring System for Elderly Patient

The joy of the loved ones is among the key factors to our happier lives. For the best life, people require extra attention from health monitoring point in order to stay healthy and safe. Therefore, a practical innovation product to monitor patient health such as the elderly monitoring system are developed and proposed in this article. The product is based on IoT where it can monitor the body's temperature, pulse rate and respiratory rate of the patient on a long distance using smartphones. The proposed system uses nodeMCU as a microcontroller, three sensors units and ThingSpeak as application platform. A smart lifestyle typically among the elderly can be developed using innovative products like this in the future. It can help doctors and guardians to monitor elderly patients from long-haul distance. &nbsp

Design and Built a Prototype Kit for Fire Detection in a Peat Swamp Forest: A Preliminary Results

Peat forest fire detectors need to be developed immediately due to the frequency of peat forest fires in Malaysia during the summer is very high which can affect the life in the forest and the health of the surrounding population. Among them is the Ayer Hitam Muar Forest Reserve, Johor which is almost 50,000 acres in size and experiences fires every year. However, fire monitoring management methods still need to be improved in terms of speed, accuracy and systematic in channelling fire alerts. Apart from location and area factors, the main challenge of the early fire detection process is the lack of manpower for the purpose of monitoring and notification of fires. The conventional method through patrols and phone calls from farmers who see a fire is less effective because of the delay in notification received by the authorities. Initially, the work of identifying the location of the fire and measuring the signal strength of the telco service in the Forest Reserve was done with the help of rangers from the Muar district forestry department. This article proposes a propotype for detecting peat forest fires that is capable of monitoring and sending early fire notifications using a smartphone. The prototype uses an ESP32 microcontroller, GSM/GPRS modem and industry-standard sensors which include smoke, temperature, humidity and motion detectors. A total of five prototype units were developed as sensor nodes (SN) 1 to 5 with unique IDs that can send information to UTHM web servers simultaneously. Data from each SN is displayed in real time while notifications of smoke detection and motion alerts are sent to the authorities via Telegram application. Solar panels are used as a source of electricity supply while the authorities can access information via smartphones. This prototype was tested to see its stability and operational accuracy while the data obtained were recorded. The developed system can help the authorities detect fires at an early stage and the location of the fire can be known based on the SN information received on the smartphone screen

High Sensitivity Prototype Kit with IoT System for Fire Detection in a Peatland Swamp Forest Area

Smoke sensor of the photoelectric type is often used in indoor fire detection system. It is very sensitive to fire smoke and will trigger a fire alarm quickly when the presence of smoke is detected. By making a small innovation, this sensor can be implemented outdoors by means of IoT as used in the forest fire early detection system. However, the typical use of the sensor without any modification causes the sensitivity of the system to be very low such as failing to identify the actual presence of smoke. To increase the sensitivity of systems that use this type of sensor, the developed system is equipped with an automatic reclosing operation that is able to distinguish real smoke or not. The system has been designed to trigger cloud servers only after detecting smoke for ten seconds or beyond. System equipped with automatic reclosing operation show better response by not triggering cloud servers when detecting temporary smoke from car, motorcycle or nearby factory. When comparing the system before and after using this operation is, it was found that the system no longer sends smoke notification message to the user via Telegram channel when this temporary smoke is detecte

High Sensitivity Prototype Kit with IoT System for Fire Detection in a Peatland Swamp Forest Area

Smoke sensor of the photoelectric type is often used in indoor fire detection system. It is very sensitive to fire smoke and will trigger a fire alarm quickly when the presence of smoke is detected. By making a small innovation, this sensor can be implemented outdoors by means of IoT as used in the forest fire early detection system. However, the typical use of the sensor without any modification causes the sensitivity of the system to be very low such as failing to identify the actual presence of smoke. To increase the sensitivity of systems that use this type of sensor, the developed system is equipped with an automatic reclosing operation that is able to distinguish real smoke or not. The system has been designed to trigger cloud servers only after detecting smoke for ten seconds or beyond. System equipped with automatic reclosing operation show better response by not triggering cloud servers when detecting temporary smoke from car, motorcycle or nearby factory. When comparing the system before and after using this operation is, it was found that the system no longer sends smoke notification message to the user via Telegram channel when this temporary smoke is detecte

Modelling and analysis of complex electromagnetic problems using FDTD subgridding in hybrid computational methods

The main objective of this research is to model and analyse complex electromagnetic problems by means of a new hybridised computational technique combining the frequency domain Method of Moments (MoM), Finite-Difference Time-Domain (FDTD) method and a subgridded Finite-Difference Time-Domain (SGFDTD) method. This facilitates a significant advance in the ability to predict electromagnetic absorption in inhomogeneous, anisotropic and lossy dielectric materials irradiated by geometrically intricate sources. The Method of Moments modelling employed a two-dimensional electric surface patch integral formulation solved by independent linear basis function methods in the circumferential and axial directions of the antenna wires. A similar orthogonal basis function is used on the end surface and appropriate attachments with the wire surface are employed to satisfy the requirements of current continuity. The surface current distributions on structures which may include closely spaced parallel wires, such as dipoles, loops and helical antennas are computed. The results are found to be stable and showed good agreement with less comprehensive earlier work by others. The work also investigated the interaction between overhead high voltage transmission lines and underground utility pipelines using the FDTD technique for the whole structure, combined with a subgridding method at points of interest, particularly the pipeline. The induced fields above the pipeline are investigated and analysed. FDTD is based on the solution of Maxwell’s equations in differential form. It is very useful for modelling complex, inhomogeneous structures. Problems arise when open-region geometries are modelled. However, the Perfectly Matched Layer (PML) concept has been employed to circumvent this difficulty. The establishment of edge elements has greatly improved the performance of this method and the computational burden due to huge numbers of time steps, in the order of tens of millions, has been eased to tens of thousands by employing quasi-static methods. This thesis also illustrates the principle of the equivalent surface boundary employed close to the antenna for MoM-FDTD-SGFDTD hybridisation. It depicts the advantage of using hybrid techniques due to their ability to analyse a system of multiple discrete regions by employing the principle of equivalent sources to excite the coupling surfaces. The method has been applied for modelling human body interaction with a short range RFID antenna to investigate and analyse the near field and far field radiation pattern for which the cumulative distribution function of antenna radiation efficiency is presented. The field distributions of the simulated structures show reasonable and stable results at 900 MHz. This method facilitates deeper investigation of the phenomena in the interaction between electromagnetic fields and human tissues