Universal Mobile Telecommunications Service Research Articles

Identification of Cellular Signal Measurements Using Machine Learning

Spectrum awareness has a plethora of civilian and defense applications, such as spectrum resource management, adaptive transmissions, interference detection, and identification of threat signals. This article proposes an identification neural network (INN)-based model that identifies cellular signals from three different radio access technologies, namely global system for mobile (GSM) communications, universal mobile telecommunications service, and long-term evolution. The proposed INN identifies whether or not the measured power spectral density belongs to a certain cellular signal type. Two data collection approaches (DCAs) are considered: in-band and multiple-band. The over-the-air measurements for the two DCAs show that with low computational complexity, the proposed INN model provides an identification accuracy between 93% and 100%, with a false alarm (FA) rate between 0% and 10%.

A novel approach for optimization of handover mechanism using metaheuristics algorithms

The new generation wireless system is an integrated global network, which provides many services for end users across the globe. The major requirement of end users is to allow the mobile user to roam seamlessly across the network. Heterogeneous Wireless Networks (HWNs) permit users with global devices to access the required service at any place and anywhere. The HWNs contain many Radio Access technology RATs such as GPRS (General Packet Radio Services), UMTS (Universal Mobile Telecommunication Service), Wi-Fi (Wireless Fidelity), Wi-Max (Worldwide Interoperability for Microwave Access), WLAN (Wireless Local Area Network) and transferring the ongoing call and providing seamless mobility can be achieved by Vertical Handover (VHO) mechanisms. The heterogeneous wireless networks (HWN) integrated with the network characteristics, like the bandwidth, speed support, cost, security, power consumption, delay, and range of communication are employed for obtaining better Quality of Services (QoS). For better mobility management, handover (HO) is the most significant aspect considered for solving the issues regarding mobility the designed Novel approach uses metaheuristics algorithms like grey wolf optimization (GWO) and Mayfly optimization (MFO) technique to provide a better service for end-user in terms of energy consumption, and handover delay, Call drop probability and throughput.

Design and implementation of a dual band bioinspired leaf rectenna for RF energy harvesting applications

In this article, both design and implementation of a novel Omni-directional bioinspired Linden leaf-shaped rectenna are reported. The antenna is designed for the energy harvesting purposes under the operation frequency range between 1.6 and 2.65 GHz with a second harmonic rejection property. At the rectifier stage, voltage doubler circuit is designed and implemented with the help of microstrip transmission lines, which are used for impedance matching procedure between the antenna and the rectifier for the optimum power transfer from the antenna to the load for the operation dual bands of universal mobile telecommunication service and WIFI. In the design, SMS7630Schottky diodes, high frequency capacitors and inductors are used as the main surface mount devices. The FR4 epoxy material is selected as a substrate material for both the antenna and the rectifier circuit due to its low cost and easy—production scheme. The maximum efficiency value realized at the dual band operation is 42% at the 0 dBm input power level. The output voltage value and the harvested power at this point are nearly 960 mV and 0.42 mW with an optimum load RL = 2.2 KOhm. The implemented system can be used efficiently for the RF energy harvesting applications for the proposed frequency bands.

Novel Design of Penta Band Planar Inverted F Antenna for Wireless Communication

In this paper, a novel penta-band internal single feed low profile Planar Inverted F Antenna (PIFA) that operates in several bands including Global System for Mobile Communication GSM 900 MHz, GSM 1800 MHz, Global Positioning System (GPS), Universal Mobile Telecommunications Service UMTS 2100 MHz, 1800 MHz, Advanced Wireless Services AWS 1700 MHz and Industrial, Scientific and Medical Band ISM 2.4 GHz has been proposed. The proposed antenna has a rectangular and slotted radiating patch suspended above a rectangular ground plane, which is also slotted. A 0.6 mm thick FR4 dielectric substrate of the same size as the rectangular ground plane has been used between the radiating patch and the ground plane. By optimizing the slots on the radiating patch as well as the ones on the ground plane, it has been noticed that the antenna can work at five distinct bands of frequencies with good operating bandwidth. The slots on the ground plane have contributed further to generate multiband frequencies with improved bandwidth and to form almost omnidirectional radiation patterns at the resonating frequencies. The simulation and the analysis of the proposed antenna have been done using Computer Simulation Technology (CST) Studio Suite software. This novel compact penta band PIFA antenna shows very good performance at all the frequencies of operations and it will be a suitable candidate for wireless communications.

Concentric Ring Structured Reconfigurable Antenna using MEMS Switches for Wireless Communication Applications

This paper proposes a reconfigurable circular microstrip antenna to serve the wireless communication applications that make use frequency bands such as ISM (Industrial Scientific and Medical), WLAN (Wireless Local Area Network), UMTS (Universal Mobile Telecommunications Service). Reconfigurability is achieved with the help of four MEMS (Micro-Electro-Mechanical Systems) switches to change the frequency and radiation properties of the antenna. By choosing either of the two states of each of the MEMS switches, the radius of the circular patch is varied and subsequently the operating resonant frequency. This gives rise to multiple configurations of the antenna to serve for different wireless applications. Defected Ground Structure is employed in this design to lower the resonant frequency and improve the bandwidth. Concentric rings are implemented along with a core circular patch in order to increase the radiating area of the patch in association with the MEMS-based switches to operate in toggle mode of ON and OFF. The concentric rings also helping in obtaining dual-frequency behavior of the antenna and the measured results are showing good agreement with the simulation results.

Design of a Compact Dual-Band MIMO Antenna System with High-Diversity Gain Performance in Both Frequency Bands.

A compact four-element dual-band multiple-input and multiple-output (MIMO) antenna system is proposed to achieve high isolation and low channel capacity loss. The MIMO antenna was designed and optimized to cover the dual-frequency bands; the first frequency band is a wide band, and it covers the frequency range of 1550–2650 MHz, while the other frequency band covers the 3350–3650 MHz range. The measured wide-band impedance bandwidths of 1.1 GHz and 300 MHz were achieved in the lower and upper frequency bands, respectively. The proposed structure consists of four novel antenna elements, along with a plus-sign-shaped ground structure on an FR4 substrate. The overall electrical size of the whole dual-band MIMO antenna system is (W) × (L) × (H) for the lower frequency band. It achieved greater than 10 and 19 dB isolation in the lower and upper frequency bands, respectively. The antenna system accomplished an envelope correlation coefficient of in the lower frequency band, while it achieved in the higher frequency band. The computed channel capacity loss remained less than almost 0.4 bits/s/Hz in both frequency bands. Therefore, it achieved good performance in both frequency bands, with the additional advantage of a compact size. The proposed MIMO antenna is suitable for compact handheld devices and smartphones used for GSM (Global System for Mobiles), UMTS (Universal Mobile Telecommunications Service), WCDMA (Wideband Code Division Multiple Access), LTE (Long Term Evolution), 5G sub-6 GHz, PCS (Personal Communications Service), and WLAN (wireless local area network) applications.

Comparison of Average Total EMF Exposure for Microcell/Macrocell Topologies Using Novel Methodology Based on Operational Network Measurements

Two outdoor base station macrocell/microcell topologies in operational Global System for Mobile communications (GSM) and Universal Mobile Telecommunications Service (UMTS) networks are compared with respect to average Electromagnetic Field (EMF) exposure over population in an area. A novel joint metric is used, accounting for exposure from both base stations and user equipment. The demonstrated method tends to use as much data as possible that can be extracted from various network systems, for the exact time of measurements or on long-term basis, with the aim of identifying the potential for EMF-awareness of future networks. The reduction of total exposure with the introduction of the microcell layer is shown using the proposed method with experimental measurements and compared by mobile network technologies. The introduction of the micro layer brought reduction to total population exposure of 84.6%, in the micro base station coverage area, mostly due to user device exposure reduction in GSM. UMTS user device exposure reduction was even more pronounced, 97.8%, but having less impact on overall exposure, contributing only 1%. Even with the increase in exposure originating from base stations, the reduction of total exposure was visible over the macro area as well, measuring 2.22%. The uncertainties of the evaluation method are identified and usage of advanced tools and methods is proposed to mitigate them.

Multiband inverted E and U shaped compact antenna for Digital broadcasting, wireless, and sub 6 GHz 5G applications

A novel dual branch multiband compact slotted antenna for digital broadcasting, wireless and sub 6 GHz 5G is presented. Antenna achieves multiband characteristics at (750–790 MHz) Digital broadcasting, (1.41–1.45 GHz) wireless medical telemetry, (2.10–2.14 GHz) Universal Mobile Telecommunication Service (UMTS), (3.44–3.51 GHz) WiMAX/sub 6 GHz 5G, (3.80–3.87 GHz) Sub 6 GHz 5G, (5.17–5.20 GHz) wireless local area network (WLAN) and (5.97–6.38 GHz) fixed satellite communication by introducing slots in the form of inverted U and E shape having varied branch lengths and full ground plane. The antenna has an overall size of 30 × 30 × 1.6 mm3. The proposed antenna achieves compact operation along with an omnidirectional radiation pattern having gain and efficiency in the range over 1.1 dBi and 78% for the proposed frequency bands. The antenna is fabricated after optimizing the geometrical dimensions where measured results match well with simulated ones.

Long-term effect of mobile phone use on sleep quality: Results from the cohort study of mobile phone use and health (COSMOS)

BackgroundEffects of radiofrequency electromagnetic field exposure (RF-EMF) from mobile phone use on sleep quality has mainly been investigated in cross-sectional studies. The few previous prospective cohort studies found no or inconsistent associations, but had limited statistical power and short follow-up. In this large prospective cohort study, our aim was to estimate the effect of RF-EMF from mobile phone use on different sleep outcomes. Materials and methodsThe study included Swedish (n = 21,049) and Finnish (n = 3120) participants enrolled in the Cohort Study of Mobile Phone Use and Health (COSMOS) with information about operator-recorded mobile phone use at baseline and sleep outcomes both at baseline and at the 4-year follow-up. Sleep disturbance, sleep adequacy, daytime somnolence, sleep latency, and insomnia were assessed using the Medical Outcome Study (MOS) sleep questionnaire. ResultsOperator-recorded mobile phone use at baseline was not associated with most of the sleep outcomes. For insomnia, an odds ratio (OR) of 1.24, 95% CI 1.03–1.51 was observed in the highest decile of mobile phone call-time (>258 min/week). With weights assigned to call-time to account for the lower RF-EMF exposure from Universal Mobile Telecommunications Service (UMTS, 3G) than from Global System for Mobile Communications (GSM, 2G) the OR was 1.09 (95% CI 0.89–1.33) in the highest call-time decile. ConclusionInsomnia was slightly more common among mobile phone users in the highest call-time category, but adjustment for the considerably lower RF-EMF exposure from the UMTS than the GSM network suggests that this association is likely due to other factors associated with mobile phone use than RF-EMF. No association was observed for other sleep outcomes. In conclusion, findings from this study do not support the hypothesis that RF-EMF from mobile phone use has long-term effects on sleep quality.

Introduction to inmarsat broadband global area network for mobile backbone networks

In this paper is introduced the Inmarsat Global Area Network (GAN) as backbone to mobile networks. At the end of 2005 Inmarsat launched its BGAN service as the first high speed wireless data solutions with voice available on a global basis. The service is accessed through a portable, broadband satellite transceiver with antenna easy to carry as a laptop. The BGAN network consists constellation of Geostationary Earth Orbit (GEO) I-4 and I-5 satellites with an optimized ground network, which interconnects variety of terrestrial infrastructures at local BGAN users. This system employs bandwidth efficient modulation and coding techniques, capable of supporting variable bit-rate services and QoS depending on the needs of the application. The BGAN system is satellite component of 3G IMT-2000, specially the Universal Mobile Telecommunications Service (UMTS) standards. It will provide a near-global coverage overlay for the terrestrial networks, giving users service availability beyond the reach of terrestrial IMT-2000 networks. A range of supported terminals, personal devices, portable and mobile units linked with onboard entertainment, communications systems to remote base stations for civilian and military applications and SCADA or M2M are discussed.

A differential triple band antenna based Energy Harvesting System

A triple band differential rectenna for RF energy harvesting applications is proposed in this paper. The rectenna is designed to operate in frequency bands of universal mobile telecommunication service (2.1 GHz), lower WLAN/Wi- Fi (2.4– 2.48 GHz), and WiMAX (3.3–3.8 GHz). For designing the proposed rectenna, initially a differentially fed multiband slot antenna that works as the front-end receiving unit is designed, fabricated, and tested to check its performance. In the next step, a triple band differential rectifier is designed using the Villard voltage doubler where inter digital capacitors (IDCs) in lieu of lumped components are used. The full rectifier circuit comprising of the rectifying unit and impedance matching circuit is fabricated and tested to check its performance in the desired bands. The peak RF-dc conversion efficiency of 68% is obtained using the three-tone measurement. In the final stage, both antenna and the rectifier circuit are integrated through SMA connecter in order to implement the proposed rectenna.

An optimized multi‐attribute vertical handoff approach for heterogeneous wireless networks

SummaryWireless networking is becoming an increasingly important and popular way of providing global information access to users on mobility. Considering the accessibility of different advances, it is hard to choose the best system that guarantees client fulfilment. The best network selection in heterogeneous condition is a primary research issue. In Dynamic Network Selection Function (DNSF) method, which employs physical layer metrics as criteria for network selection, computation of functions‐based relative dynamic weight optimization is proposed. This method is implemented through simulation in a typical heterogeneous wireless environment of Universal Mobile Telecommunications Service (UMTS) and Wireless Local Area Network (WLAN). The number of unnecessary handover occasions with the Handoff failure rate of the client between accessible systems is utilized as the execution measurements, and constantly best‐associated system is chosen in view of the cost function. It is inferred that DNSF based approach yields ideal system determination in heterogeneous condition.

Experimental analysis of individual EMF exposure for GSM/UMTS/WLAN user devices

Individual exposure to electromagnetic field (EMF) originating from a user device when using different services over WLAN (Wireless Local Area Network), GSM (Global System for Mobile communications), and UMTS (Universal Mobile Telecommunications Service) technologies in different radio conditions is analyzed. The most common types of traffic were chosen (voice, Skype, web browsing, download, upload, video, audio, TV) and tested in areas of good, medium, and bad radio conditions, per wireless technology. Exposure is evaluated using triggered network reports and external measurements performed in a live network, and also using predetermined simulation results. The analysis shows strong dependence of individual EMF exposure on wireless technology, radio conditions, and service used. For all technologies and services, exposure increased with deterioration of radio conditions, except for file upload over UMTS where in bad radio conditions exposure decreased due to impact of higher layer protocols. GSM technology generated highest exposure in all radio conditions and for all services, except file upload service in good radio conditions where WLAN generated higher exposure. File upload service generated highest exposure for all technologies and radio conditions, except for GSM in good radio conditions where video streaming and voice were ahead.

Design of Triple Band Differential Rectenna for RF Energy Harvesting

A triple band differential rectenna for RF energy harvesting applications is proposed in this paper. The rectenna is designed to operate in frequency bands of universal mobile telecommunication service (2.1 GHz), lower WLAN/Wi-Fi (2.4–2.48 GHz), and WiMAX (3.3–3.8 GHz). For designing the proposed rectenna, first a differentially fed multiband slot antenna that works as the front-end receiving unit is designed, fabricated, and tested to check its performance. It is observed that a peak antenna gain of 7, 5.5, and 9.2 dBi is achieved at 2, 2.5, and 3.5 GHz, respectively. In the next step, a triple band differential rectifier is designed using the Villard voltage doubler where interdigital capacitors (IDCs) in lieu of lumped components are used. The full rectifier circuit comprising of the rectifying unit and impedance matching circuit is fabricated and tested to check its performance in the desired bands. The peak RF-dc conversion efficiency of 68% is obtained using the three-tone measurement. In the final stage, both antenna and the rectifier circuit are integrated through SMA connecter in order to implement the proposed rectenna. Measurement of the proposed rectenna shows an approximate maximum efficiency of 53% at 2 GHz, 31% at 2.5 GHz, and 15.56% at 3.5 GHz.

Dual‐band meander‐line MIMO antenna with high diversity for LTE/UMTS router

A dual-band multiple-input multiple-output (MIMO) antenna is presented. The proposed MIMO antenna consists of two elements of meander-line antenna with an isolation improvement structure located between the two radiating antenna elements. The antennas operate in the 4G long-term evolution (LTE) (699-798 MHz) band, and Universal Mobile Telecommunications Service (UMTS) (Digital Cellular System (DCS)/Personal Communications Service (PCS)) bands (1920-2170 MHz) with | S 11 | = -6 dB (voltage standing wave ratio (VSWR) = 3) matching criteria. The measured mutual coupling is lower than -15 and -22 dB at the LTE 700 bands, and UMTS bands, respectively. The diversity performance of the envelope correlation coefficient and the mean effective gain meets the diversity criteria for mobile communications. Total radiation efficiencies range between 60 and 90% over the operating frequency bands. A prototype antenna was fabricated and tested for design verification. The simulated results are in good agreement with the measurements.

A triple-band dipole antenna for UMTS/LTE and UWB applications

ABSTRACTIn this paper, an ultra-wideband (UWB) dipole antenna with integrated Universal Mobile Telecommunications Service and long-term evolution 2.5 GHz band has been presented. The design process involves loading L-shaped and meandered line slots on UWB dipole antenna for achieving triple-band characteristics. The proposed antenna offers a small electrical size of 0.18λo * 0.23λo * 0.01λo with impedance bandwidths (|S11| < −10dB) of 11%, 6.5% and 127.7% centred at 2 GHz, 2.6 GHz and 10.8 GHz, respectively. The designed antenna shows good radiation characteristics with appreciable gain and omnidirectional radiation patterns over the operating bandwidth with satisfactory time domain performance. A prototype has been fabricated and tested in order to validate the simulation results.

Low specific absorption rate microstrip patch antenna for cellular phone applications

The aim of this study is to design a new microstrip-fed patch antenna for cell phone applications. The antenna design is composed of slots and Flame Retardant 4 dielectric substrate fed by a partial ground plane and a microstrip line. The user's effects on antenna performances are also analysed using standard specific anthropomorphic mannequin head phantom. The specific absorption rate (SAR) values of the proposed antenna are evaluated for different frequency bands considering cheek position of talk mode. The proposed antenna has an impedance bandwidth of 230.4 MHz (0.725-0.95 GHz, lower band), and 522.24 MHz (1.74-2.25 GHz, upper band), which can cover global system for mobile (GSM) 900 MHz, digital communication system 1800 MHz, personal communications service 1900 MHz, GSM 1900 MHz, and universal mobile telecommunications service 2100 MHz bands. Moreover, the proposed antenna produces lower SAR values in the human head than that of a dipole antenna, helical antenna, and planar inverted-F antenna.

Competitive Strategies and Improved Performance of Selected Nigeria Telecommunication Companies

The influence of globalization in telecommunication companies has greatly increased the level of competition in the industry and they are forced to be competitive to survive. Different types of strategies are put in place in order to be profitable and competitive. All these strategies are directed to attract, retain and maintain customers for continuous profitability. However, majority of them hardly measure the impact of their strategic innovation on their customers. The paper seeks to explore the influence of competitive strategies embarked upon by selected telecommunication companies in Nigeria on their performance. The paper also examines how competitive strategies could be implemented for improved customer satisfaction, retention and loyalty. Three null hypotheses were postulated to test the relationship between lower prices and customer satisfaction, uninterrupted trunk services and customer loyalty, and customer complaint handling and retention. Only customers using telephone service were selected as respondents from Lagos State. The state was stratified in to 20 local government council area and questionnaires were distributed to 125 respondents in each of them. The completion rate of the questionnaire in each of them is between 103 and 110. Survey research design was adopted to carry out the study. A structured questionnaire was designed and validated through the construct validity and tested for confirmation using the KMO measure of sampling adequacy. It was also made reliable using Cronbach’s Alpha test. From the study, findings revealed relationship between competitive strategies and customer satisfaction, retention and loyalty. The findings revealed that there is a relationship between competitive strategies, its constituents and performance of telecommunication companies. It is recommended that universal mobile telecommunication services (UMTS) operators should adopt the culture of competitive strate

ENGLISH

Radio Frequency is abundandly available in an outdoor environment. The number of existing RF bands is impulsive. The RF circuit has to harvest all the potential RF energy present and cannot be premeditated for a specific RF tone. The designed rectenna adds powers coming from an limiteless number of sub frequency bands. The designed rectenna output voltage increase with the number of RF bands. As an application, a Radio Frequency band rectenna is designed. The system uses PIFA (Planar Inverted F Antenna) to harvests energy from GSM900 (Global System for Mobile Communications) ,GSM1800, UMTS (Universal Mobile Telecommunication Service) and WiFi bands simultaneously. The planar inverted F antenna is popular for portable devices because of its low profile, small size, and built-in structure. The radiated power from the antenna is given as input to the rectifier. The schottky diode is used for rectification. Inorder to get maximum power to the load the T matching is used to get an proper impedance matching. The seven stage voltage doubler of HSMS 2850 is introduced in the circuit in order to get maximum voltage to supply the low power devices.

A Concurrent Transmission Scheme for in Heterogeneous Wireless Network

Integration of the wireless LANs (WLAN) and 3G networks, such as Universal Mobile Telecommunication Service (UMTS), has been intensively studied recently due to their complementary characteristics. In this paper, we design and implement a flexible protocol stack architecture which can support concurrent transmission via multiple radio interfaces. Furthermore, the multiple services with various QoS requirements are differentiated and transported in the best wireless access network which is determined by the proposed network selection criterion-- Multi-Criteria Decision Making (MCDM), in the heterogeneous wireless network. Simulation results demonstrate that the proposed concurrent transmission scheme improves the network utility and provide the QoS services among the multiple wireless access networks more efficiently.