Showing papers on "UMTS frequency bands published in 2016"

Reconfigurable Antenna for Future Spectrum Reallocations in 5G Communications

Abstract: This letter presents a reconfigurable antenna for mobile terminals with extended band coverage obtained by using a digitally tunable capacitor (DTC). The antenna structure is matched permanently over high frequency bands including DCS/PCS, UMTS, LTE 1800/2600, and 3.5-GHz bands. Concerning the sub-GHz bands, several reconfigurable states enable a full coverage of LTE 600/700 and GSM 850/900 standards, as well as expected spectrum reallocations for 5G communications. With dimensions of 40 ×10 ×6 mm 3 for the antenna and 130 ×70 ×0.8 mm 3 for the whole printed circuit board (PCB), this structure is compatible with any mobile terminal.

Modeling and Performance Analysis of a Tracking-Area-List-Based Location Management Scheme in LTE Networks

Abstract: In a cellular network, the network coverage is partitioned into nonoverlapping areas called registration areas to facilitate location management (LM) that keeps track of the location of a user equipment (UE) unit. In the second-generation Global System for Mobile Communications (GSM) and the third-generation Universal Mobile Telecommunications System (UMTS), a registration area is called a location area (LA) in the circuit-switched domain or a routing area (RA) in the packet-switched domain. In the fourth-generation Long-Term Evolution (LTE), a registration area is called a tracking area (TA). To tackle the drawbacks of the LA/RA-based LM scheme used in GSM and UMTS, which is intrinsically a static scheme, LTE adopts a dynamic LM scheme called a TA list (TAL)-based scheme. Under the TAL-based scheme, the network allocates to a UE unit a group of TAs referred to as a TAL instead of only a single TA. The UE can move freely within the allocated TAL without performing any location updates that are called TA updates (TAUs) in LTE. Only when moving into a TA that is not included in the allocated TAL does the UE need to perform a TAU, and afterward, the network will allocate, to the UE, a new TAL. The performance of the TAL-based scheme relies on the allocated TAL. If the allocated TAL is inappropriate with respect to the UE's mobility and traffic characteristics, the TAL-based scheme may produce adverse effects. To find an optimal TAL allocation method for global UE units that exhibit weak regularity in their mobility, this paper develops an embedded Markov chain approach to analyze the signaling cost of the TAL-based scheme. This paper distinguishes itself from existing studies in the following aspects. First, this paper follows LTE technical specifications, that is, the number of TAs in a TAL can vary and, furthermore, is upper bounded, whereas existing studies partially or completely ignore this stipulation. Second, this paper emphasizes the impact of a call handling model that dictates whether a TAU occurs after the completion of a call by considering two call handling models, i.e., a call plus location update and a call without location update. Third, as for the dependence among the cell residence time, the TA residence time, and the TAL residence time, this paper proposes the use of a fluid flow model to describe this dependence, which is simple but does not compromise accuracy. Analytical formulas for the total signaling cost of the TAL-based scheme due to TAU and paging operations, as well as formulas that are useful in designing an optimal paging scheme, are derived, and their accuracy is validated through Mont Carlo simulation. Then, numerical studies are carried out to investigate the impact of diverse parameters on the signaling cost, revealing that the network can allocate, to a UE unit, an optimal TAL that is consistent with the UE's mobility and traffic characteristics to minimize the signaling cost of the TAL-based scheme.

Compact dual polarised V slit, stub and slot embedded circular patch antenna for UMTS/WiMAX/WLAN applications

Abstract: A single probe-fed novel V slit, stub and slot embedded circular microstrip antenna with resonances in the three bands of UMTS, worldwide interoperability for microwave access (WiMAX) and WLAN is presented. The polarisation is circular in the UMTS band and linear in the other two bands. Asymmetrical V slits in the patch boundary along with an embedded circular slot in the patch centre are employed to introduce the perturbation necessary for circular polarisation. Impedance bandwidths (BWs) of 4.2, 2 and 6.2%, respectively, in the three bands centred at 2, 3.5 and 5.6 GHz are obtained. The axial ratio BW is 2.3% in the UMTS band. Moderate gains of 4.4, 3.5 and 2.8 dBi are obtained in the three bands. There is a patch size reduction of about 48% when compared with the conventional circular patch antenna at a fixed operating frequency. The radiation pattern is directional in the WiMAX band and nearly omnidirectional in the WLAN band.

A Multi-wall and Multi-frequency Indoor Path Loss Prediction Model Using Artificial Neural Networks

Abstract: Indoor radio propagation prediction modeling has been for a long time an important area of interest in research and development. In the literature, many propagation models are classified into empirical and deterministic models. The accuracy of both categories of models can be improved based on model calibration or tuning that uses real measurements collected in a given environment and frequency. Based on the availability of a huge measurement database, we aimed in this paper to develop a new propagation model using artificial neural networks. The new model is inspired from multi-wall one and will be available for the most used system bands, such as GSM, UMTS and WiFi. The model will be a multilayer perceptron and is trained with measured data using a back-propagation learning algorithm. Evaluated model performances show a high improvement in terms of accuracy compared to a calibrated multi-wall model.

Radio Network Planning And Optimisation For Umts

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Multiband planar antenna for LTE/GSM/UMTS and WLAN/WiMAX handsets

Abstract: A multiband planar antenna is proposed for mobile handsets. The multiband antenna covers four frequency bands: 696-970 MHz for Long Term Evolution (LTE) 700, Global System for Mobile Communications (GSM) 850/900; 1683-2700 MHz for GSM 1800/1900, Universal Mobile Telecommunications System (UMTS) 2100, LTE 2300/2600, WLAN 2.4 GHz, WiMAX 2.5 GHz; 3070-3755 MHz for WiMAX 3.5 GHz; and 4590-7604 MHz for WLAN/WiMAX 5.2/5.8 GHz and WiMAX 5.5 GHz. The planar antenna consists of a U-shaped monopole coupling with an S-shaped strip, a clip-shaped monopole with a meander line coupling with an inverted-C strip, an X-shaped monopole, and an F-shaped monopole. The multiband antenna has a low profile and is printed on a thin substrate, suitable for ultra-slim smartphone applications.

Small-Scale Spectrum Aggregation and Sharing

Abstract: New spectrum bands together with flexible spectrum management are treated as one of the key technical enablers for achievement of the so-called key-performance indicators defined for 5G wireless networks. In this paper, we deal with the small-scale spectrum aggregation and sharing, where a set of even very narrow and disjoint frequency bands closely located on the frequency axis can be utilized simultaneously. We first discuss how such a scheme can be applied to various multicarrier systems, focusing on the non-contiguous orthogonal frequency division multiplexing and non-contiguous filter-bank multicarrier technique. We propose an interference model that takes into account the limitations of both transmitter and receiver frequency selectivity, and apply it to our 5G link-optimization framework, what differentiates our work from other standard approaches to link adaptation. We present the results of hardware experiments to validate assumed theoretical interference models. Finally, we solve the optimization problem subject to the constraints of maximum interference induced to the protected legacy systems (GSM and UMTS). Results confirm that small-scale spectrum aggregation can provide high throughput even when the 5G system operates in a dense heterogeneous network.

Systems, methods and devices for cellular synchronization references

Abstract: Cellular (e.g., LTE or UMTS) and global navigation satellite system (GNSS) based technologies can provide ubiquitous and seamless synchronization solution for LTE-based vehicle to everything (V2X) or Proximity Services synchronization (ProSe) services. For example, by using joint GNSS timing references and LTE cellular network timing references for V2X or ProSe system synchronization benefits of using GNSS technologies to improve synchronization procedure for LTE based V2X or ProSe services can be enabled, including: (1) accurate and stable timing, (2) availability of a global and stable timing reference and (3) ability to propagate GNSS timing by user equipment having sufficient GNSS signal quality.

Multi-band ambient RF energy harvesting rectifier for autonomous Wireless Sensor networks

Abstract: In this paper, a triple-band rectifier design is proposed for the ambient RF energy harvesting. Given the increasing popularity of Wireless Sensor Nodes (WSN) for the Internet of Things (IoT) application, a multi-band rectifier design offers an excellent option as power supply. The multiband approach has the advantages of achieving higher RF-to-DC conversion efficiency than the conventional single band approach, while keeping the overall size of the circuit compact. The circuit operates at three frequency bands - GSM 1800, UMTS 2100 and LTE 2600, and is able to achieve high RF-to-DC conversion efficiency, reaching 35% at input power of −20 dBm. The harvest energy is sufficient to power a number of sensors commonly used in WSN.

Enhancing RF-to-DC conversion efficiency of wideband RF energy harvesters using multi-tone optimization technique

Abstract: In this paper, a 1.8–2.6 GHz wideband rectenna is designed for radio frequency (RF) energy harvesting in the context of wireless sensor nodes (WSN). To assess the feasibility of ambient RF energy harvesting, the power density from RF base stations is analyzed through statistical measurements. Power density measurements are also performed close to Wi-Fi routers. Using these results, a methodology based on impedance matching network adaptation and maximum power transfer is proposed to design the wideband RF harvester. Using this method, three RF bands, i.e. GSM1800, UMTS and WLAN, are covered. The theoretical analysis is confirmed by simulations and measurements. From measurements results, the prototype RF-to-DC conversion efficiency is 15% at −20 dBm from 1.8 to 2.6 GHz. It is shown that with three RF sources in the chosen bands, each emitting at 10 dBm, the RF-to-DC conversion efficiency is 15% better compared to that measured with a single RF source. Finally, 7 µW is harvested at 50 m from a GSM1800 and UMTS base station. This value confirms the RF harvester workability to supply small sensors.

A SiGe BiCMOS Power Amplifier Using a Lumped Element-Based Impedance Tuner

Abstract: A dual-path multi-band power amplifier (PA) with a tunable output matching network is presented for long-term- evolution (LTE) handset applications. To optimize output load impedances for various power regions with various frequency bands, an impedance tuner implemented using lumped elements is used. The dual-path multi-band PA fabricated using $0.35{\mathchar"702D}\mu{\rm m}$ SiGe BiCMOS process is evaluated for the evolved UMTS terrestrial radio access (E-UTRA) bands 1, 2, 3, 5, and 8 with a 10 MHz bandwidth (BW) LTE 16 quadrature amplitude modulation signal having a peak-to-average ratio of 6.4 dB.

Assessment of mobile phone user exposure to UMTS and LTE signals: comparative near-field radiated power levels for various data and voice application services

Abstract: The aim of present research was the experimental characterization of the radiated power and its dynamics in the near-field of mobile terminal during its use in various voice and data application services belonging to either Universal Mobile Telecommunications System (UMTS) or Long-term Evolution (LTE) communication technologies. The quantification of the realistic electromagnetic exposure of human user was done by offering a complementary, non-standardized method that enables a comprehensive dosimetric understanding of radiation impact. Statistical analysis was applied over the radiated power levels measured in different wireless communication situations followed by average and worst case exposure highlighting. Highest power levels were measured for uploading-type applications running under both UMTS and LTE networks. Among UMTS voice application services, VoIP-radiated power levels were on average 1.4 higher than those for VoCS services. The multiplication factor of the radiated power in LTE vs. ...

Network Selection Using AHP for Fast Moving Vehicles in Heterogeneous Networks

Abstract: In today’s world, there are various means of accessing the Internet such as cellular, wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX), etc., for the mobile users. Also, various applications demand different quality of service (QoS) parameters. But for seamless connectivity in the case of fast moving vehicles, velocity of vehicle becomes an important issue. Traditional schemes trigger the handover process based on signal strength. These schemes do not incorporate the network parameters and user preferences required for optimal vertical handover. In this paper, analytic hierarchy process (AHP) method has been used for network selection in heterogeneous environments for moving vehicles. The method has been applied for various types of applications like conversational, streaming, interactive, and background applications. From the results, it has been found that WLAN’s performance degrades significantly when the vehicles are moving at higher velocities while Universal Mobile Telecommunication Systems (UMTS) performs best for fast moving vehicles.

Modeling City-Canyon Pedestrian Radio Channels Based on Passive Sounding in In-Service Networks

Abstract: Recently, a measurement campaign for characterizing time-variant radio channels in city-canyon environments was conducted along a 2-km-long pedestrian shopping street in Shanghai. A passive sounding approach was adopted where a software-defined-radio platform is used as a receiver (Rx) to record downlink signals transmitted by base stations (BSs) in an in-service Universal Mobile Telecommunications System (UMTS). Channel impulse responses are calculated from the data received in common pilot channels, and a space-alternating generalized expectation–maximization (SAGE) algorithm is applied to estimate delays, Doppler frequencies, and complex attenuations of multipath, which are further grouped into clusters characterized by time-evolving parameters. Based on the observations from a total of 70 BSs, stochastic models are established for composite channel parameters, cluster-level characteristics, and the time variabilities of these parameters. The novelties of the models lie in the passive data acquisition, which leads naturally to superior model ergodicity and higher fidelity than the standard models constructed based on active sounding. Furthermore, the models proposed here also exploit a new channel categorization method that takes into account the realistic impact of system configurations, such as the usage of multiple remote radio units in a single BS.

Optimized network selection during handover using analytic hierarchy process in 4G network

Abstract: In mobile communication, User Equipment (UE) always demands to be on the network and to perform different errands using applications like file transfer, video streaming and conferencing and other applications like messaging, etc. It needs higher bit rate and hence, UE in recent networks like 4G heterogeneous wireless network continuously use vertical and horizontal handover. For better Quality of Service (QoS) performance network selection is crucial in nature. In this paper, innovative method is used to select the optimal network from available networks that achieves the better QoS performance. The aggregation of multiple criteria for calculation of overall ranking of networks is obtained by Analytical Hierarchy Process (AHP) to resolve the issue of inconsistency. Finally, numerical analysis is conducted in order to determine how the proposed method works to select the network among WLAN, WiMaX and UMTS and confirm its effectiveness.

A geometry-based path loss model for high-speed-train environments in LTE-A networks

Abstract: In this paper, a recently conducted measurement campaign for High-Speed-Train (HST) channels is introduced where the down-link signals of in-service Long Time Evolution-Advanced (LTE-A) networks deployed along a HST railway between Beijing to Shanghai were acquired. The channel impulse responses (CIRs) are extracted from the received Cell-specific Reference Signals (CRSs). The results show that, most of the channels contain a delay trajectory corresponding to a line-of-sight (LoS) path. The geometry parameters such as the train speed and the minimal distance between the transmitter and the receiver are extracted from the delay trajectories. Furthermore, path loss characteristics along the trajectories are investigated and compared with the model extracted for the Universal Mobile Telecommunications System (UMTS).

Design and Testing of a Mobile-Phone-Jammer

Abstract: Dissimilar cellular-systems process signals differently, and yet, all cell-phone-networks use radio-signals that can be interrupted or, even, blocked, completely. This project highlights the design of a simple, low-cost mobile-phone-jammer and aims to present a solution for the problem of inappropriate-use of the cell-phones in restricted and prohibited-areas. The main concept of jamming is the releasing of signal (noise) of the same-frequency which is using by mobile-service-provider to overpower and destruct the user-signal. The fabrication of the jammer involved uncomplicated discrete components, resistors, capacitors, inductors and transistors to generate the required frequency ( noise ) and then amplifies the frequency generated to range of 800 MHZ to 1.4 GHZ in order to match the frequency of the mobile-phone being transmitted by the base-station. Relatively-satisfactory-jamming of a mobile-signal was confirmed by the blocking of the signals of the mobile-phones in 2G and 3G-networks (UMTS / WCDMA) operated via Safaricom, Airtell, Orange, and YU service-providers, when the phone indicated “ no network ”, thereby allowing no call to go through, with no-interference to other communication-means observed. Overall recommendation is that further and more deeper-research is needed to produce more-sophisticated and better jamming devices, as not to affect the other base-station-transmission-systems. Keywords: mobile, phone, jammer, design, signal.

Latency Analysis in Real LTE Networks for Vehicular Applications

Abstract: In the development path to implement V2X (Vehicle-to-Vehicle and Vehicle-to-Infrastructure) communications, two different, but not entirely concurrent approaches, are been investigated: the use of a new technology standard, 802.11p, denoted as DSRC/WAVE (Dedicated Short Range Communications/Wireless Access in Vehicular Environments), and the use of an already established technology, UMTS/LTE (Universal Mobile Communications System/Long Term Evolution). The choice to invest in one of these two technologies to build a V2X infrastructure passes through which one will provide a minor latency communication time between network nodes. This paper presents a measure of this parameter in mobile networks of real mobile service providers, distinguishing between data obtained from UMTS and LTE servers. Furthermore, is presented an architecture where the smartphone is a gateway to provide V2X communications, in regards that this device has a widespread adoption and can in rapidly pace turn the car a node in the Internet of Things.

An Enhanced Buffer Management Scheme for Multimedia Traffic in HSDPA

Abstract: High Speed Downlink Packet Access (HSDPA) was introduced to UMTS radio access segment to provide higher capacity for new packet switched services. As a result, packet switched sessions with multiple diverse traffic flows such as concurrent voice and data, or video and data being transmitted to the same user are a likely commonplace cellular packet data scenario. In HSDPA, Radio Access Network (RAN) buffer management schemes are essential to support the end-to-end QoS of such sessions. Hence in this paper we present the end-to-end performance study of a proposed RAN buffer management scheme for multi-flow sessions via dynamic system-level HSDPA simulations. The scheme is an enhancement of a Time-Space Priority (TSP)queuing strategy applied to the Node B MAC-hs buffer allocated to an end user with concurrent real-time (RT) and non-real-time (NRT) flows during a multi-flow session. The experimental multiflow scenario is a packet voice call with concurrent TCP-based file download to the same user. Results show that with the proposed enhancements to the TSP-based RAN buffer management,end-to-end QoS performance gains accrue to the NRT flow without compromising RT flow QoS of the same end user session.

Design of high gain, low power CMOS multi-standard LNA

Abstract: RF front-end defines everything between antenna and IF stage-including filter, amplifier and mixer. Low Noise Amplifier is an important building block of wireless receiver. A single-ended multi-standard CMOS LNA is designed for reconfigurable applications. The design addresses GSM, GPS, WCDMA, UMTS and LTE frequency bands. Based on wideband input matching, the designed LNA covers all band of interest. For multi-standard aim, capacitive switching technique is used to select desired bands of interest. The design is implemented using 90nm CMOS technology, achieving a Voltage Gain more than 30dB, Noise Figure less than 5dB and IIP3 better than −5dBm. The LNA consumes 6.2mW power at supply of IV.

Self-Diagnosing Low Coverage and High Interference in 3G/4G Radio Access Networks based on Automatic RF Measurement Extraction

Abstract: This paper presents a new approach for automatic detection of low coverage and high interference scenarios (overshooting and pilot pollution) in Universal Mobile Telecommunications System (UMTS) /Long Term Evolution (LTE) networks. These algorithms, based on periodically extracted Drive Test (DT) measurements (or network trace information), identify the problematic cluster locations and compute harshness metrics, at cluster and cell level, quantifying the extent of the problem. Future work is in motion by adding self-optimization capabilities to the algorithms, which will automatically suggest physical and parameter optimization actions, based on the already developed harshness metrics. The proposed algorithms were validated for a live network urban scenario. 830 3rd Generation (3G) cells were self-diagnosed and performance metrics were computed. The most negative detected behaviors regards high interference control and not coverage verification.

Evolutionary Analysis of GSM, UMTS and LTE Mobile Network Architectures

Abstract: The Global System for Mobile Communications (GSM) which is a standard for 2G (second generation) cellular networks has created an avenue for the development of 3G (third generation) and 4G (fourth Generation) cellular network standards such as Universal Mobile Telecommunications System (UMTS) and long term evolution (LTE). With the deployment of new technologies still on the way, the era beyond 3G and 4G requires that cellular and radio technologies need to work together forming highly heterogeneous networks, therefore this paper analyses already existing cellular network technologies such as LTE, GSM and UMTS in order to give a general understanding of their architectures, functional and evolutional dependencies and also to provide an evolutionary trend and a clear overview of the support provided for other telecommunications infrastructure.

Desktop exposure system and dosimetry for small scale in vivo radiofrequency exposure experiments.

Abstract: This paper describes a new approach to the risk assessment of exposure from wireless network devices, including an exposure setup and dosimetric assessment for in vivo studies. A novel desktop reverberation chamber has been developed for well-controlled exposure of mice for up to 24 h per day to address the biological impact of human exposure scenarios by wireless networks. The carrier frequency of 2.45 GHz corresponds to one of the major bands used in data communication networks and is modulated by various modulation schemes, including Global System for Mobile Communications (GSM), Universal Mobile Telecommunications System (UMTS), Radio Frequency Identification (RFID), and wireless local area network, etc. The system has been designed to enable exposures of whole-body averaged specific absorption rate (SAR) of up to 15 W/kg for six mice of an average weight of 25 g or of up to 320 V/m incident time-averaged fields under loaded conditions without distortion of the signal. The dosimetry for whole-body SAR and organ-averaged SAR of the exposed mice, with analysis of uncertainty and variation analysis, is assessed. The experimental dosimetry based on temperature measurement agrees well with the numerical dosimetry, with a very good SAR uniformity of 0.4 dB in the chamber. Furthermore, a thermal analysis and measurements were performed to provide better understanding of the temperature load and distribution in the mice during exposure.

Calculating the SAR distribution in two human head models exposed to printed antenna with coupling feed for GSM/UMTS/LTE/WLAN operation in the mobile phone

Abstract: The scope of this paper is to examine the Specific Absorption Rate (SAR) inside the human head model exposed to the radiation of a lowprofile printed monopole antenna with coupling feed for GSM/UMTS/LTE/WLAN operation in the slim mobile phone. The presented antenna operates for most of the mobile phone applications such as the GSM850, GSM900, GSM1900, UMTS2100, LTE2300, LTE2500 and WLAN2400 bands. In this study, two different human head models are used: homogenous spherical head and spherical seven layer model. In addition, the effects of operating frequency and the gap distance between the mobile phone antenna and the human head model on distributions of the SAR within the human head are analyzed. All the simulations are done for three different distances between the antenna and the head model (5 mm, 10 mm, 20 mm). Furthermore, the SAR levels for the head tissues are calculated for and with accordance to the two currently accepted standards: Federal Communications Commission (FCC) and International Commission on Non-Ionizing Radiation Protection (ICNIRP). All numerical simulations are performed using the Ansoft HFSS Software and CST Microwave

From 3GPP LTE to 5G: An Evolution

Abstract: All-IP network architecture is fast becoming a norm in mobile telecommunications. The International Telecommunications Union—Radio communication sector (ITU-R) recognizes a technology as 4G after haven met the International Mobile Telecommunications Advanced (IMT-A) specification of a minimum of 100 Mb/s downlink data rate for high mobility and 1 Gb/s for low mobility. The Long Term Evolution specified by the 3GPP, provides a minimum downlink data rate of 100 Mb/s and marks a new beginning in Radio Access Technologies (RATs). It also notably implements an all-IP network architecture, providing higher data rates, end-to-end Quality of Service (QoS) and reduced latency. Since the first release of the LTE standard (3GPP release 8), there have been a number of enhancements in subsequent releases. Significant improvements to the standard that enabled LTE to meet the IMT-A specifications were attained in release 10, otherwise known as LTE-Advanced. Some of the enhancements such as the use of small cells (known as femtocells) are envisioned to be the basis of fifth generation (5G) wireless networks. Thus, it is expedient to study the LTE technology and the various enhancements that will shape the migration towards 5G wireless networks. This paper aims at providing a technical overview of 3GPP LTE. With a brief overview of its architecture, this paper explores some key features of LTE that places it at the forefront in achieving the goals of wireless access evolution, enabling it to become a key element of the ongoing mobile internet growth. The migration to 5G may be radical, thus some enabling technologies that will shape the 5G cellular networks are also examined.

Near-field measurement of connected smart RFIC objects accounting for environmental uncertainties

Abstract: In this paper, we present Near-Field measurement and analysis of radiated emissions from connected smart RFIC objects. Experimental results for the characterization of Near-Field couplings between smartphones in presence of noisy interferers (GPS device in operation) are discussed. Spectral and spatial responses of radiated emissions from coupled smartphones are extracted in TX (Transmit) and RX (Receive) modes with focus on WLAN, GSM, UMTS, LTE frequency bands. Designed diversity coupled Vivaldi antenna elements for UWB applications are used for assessing the sensitivity of Near-Field detection as function of input power levels ranging from +5dBm to −130dBm. Perspectives for using noise as carrier are envisaged.

Design considerations to calculate SAR in multiband MIMO antenna for mobile handsets

Abstract: MIMO is now widely deployed in mobile devices, but existing exposure guidelines still focus on methodology for single antenna evaluation. MIMO enabled devices are required to comply with standards or internationally recognized guidelines for limiting human exposure to RF fields. Printed MIMO antennas capable of multiband operation which covers GSM 1800/1900, UMTS, WLAN, and several LTE frequency bands designed using CST studio. The flat phantom is used for testing the radiation absorption when the user places the mobile device close to the body, which is referred to as the “Body-worn mode”. The head and hand phantoms are used in the case where a user performs a voice call with the phone, which is referred to as the “Talking Mode”. SAR values calculated in these two modes, Stand-Alone SAR and MIMO SAR methods. Obtain SAR results are below the limit (1.6W/Kg).

UMTS and LTE interfaces utilization improvement with QoS in mobile communication systems

Abstract: To provide support for both data and voice is essential requirement of present mobile networks both LTE and UMTS networks. The proposed scheme in this paper differentiates assignment of requested calls on: speed, direction of motion and type of requested call. It also checks the used capacity threshold of LTE and UMTS before assignment. Different communication interfaces are used in hybrid mobile communication to address these issues, the UMTS uses VSF-OFCDM interface for assignment of orthogonal codes from orthogonal variable spreading factor (OVSF) code tree in two dimensions. The LTE interface assigns resource blocks. The UMTS is prone to high probability of packet loss and less spectral efficiency too. The LTE has problem with moderate reward with unbalanced loads. The proposed scheme reduces these issues considerably by differentiating requested calls related to interference and movement. The proposed scheme addresses these issues considerably as compared to other schemes in literature.

Multimedia quality transmission evaluation over wireless networks: a survey

Abstract: In recent years, usage of multimedia applications has increased dramatically, especially after the evolution of 3G and 4G technologies. Moreover, the development of new user devices, such as laptops, Smartphone, etc. increased very steeply and rapidly, to support different types of services and different means of communication satisfying user's needs. Here, the challenge is how to make those services available to users with a high quality; we speak here about quality of service (QoS) and quality of experience. In this survey, we examine different characteristics of wireless networks to determine the enhancements introduced by each technology. Particularly, we focus on the benefits and limitations of three main technologies which are WiMAX, UMTS and LTE, and the role of each one in increasing QoS satisfaction for multimedia application. A comparison is also done between researches already published in Multimedia quality evaluation over wireless networks topic, taking into account some considerations, such QoS parameters, used simulator, assessed applications, etc. All those help us to extract the strengths and limitations of those researches.

A multiband and reconfigurable PIFA for mobile devices

Abstract: In this paper, two compact multiband and reconfigurable planar inverted-F antenna (PIFA) designs operating at GPS, 3G, WiFi, GSM and 4G (UMTS and LTE) frequencies are presented. The multiband operation is accomplished by the multi-resonant slots while the reconfigurable PIFA operation is based on the appropriate integration of PIN diodes switches. Both antennas are proposed as suitable candidates for mobile devices' integration.