UMTS Research Articles

Comparative Analysis of Microstrip and Dielectric Resonator Antennas for UMTS Application

Recently, cellular communications knew an exponential evolution, which has benefited from the improvements of electronic components in term of miniaturization, that's why the necessity of implanting an important number of applications, made their design very tough.The key components interfacing between the radio hardware and. the air-interface for wireless communication is the antenna. Base station antennas for mobile communication systems have during the last two decades exploded in numbers in both rural and city centers. Actually, the number of frequency bands to be covered by base stations (BS) antennas has increased at the same time as the evolution of the features in the world of the mobile telephony. UMTS (Universal Mobile Telecommunications System) emerged with the development of 3G (third generation), inducing many features (Bluetooth, WI-Fi, GPS, WiMAX etc.). An Antenna can be conceived by using a variety of technologies among which we find Microstrip, and Dielectric Resonator (DR), subject of this paper. In this work we propose the design, and simulation of two different types of antennas by using Microstrip and dielectric resonator technologies for a same application, which is the UMTS. Our proposed antennas were performed with Fr4 substrate (er = 4.3; tgδ = 0.02; h = 1 mm). The two antennas parameters are compared in the aim to demonstrate advantages and disadvantages of the two technologies. The comparative study relied on simulation results performed using two numerical methods: the conception was realized by using finite integration method (CST microwave studio) and verified by finite element method (HFSS: Ansoft High Frequency Structure Simulator).

Signalling method for mobile communications network

In this study, a novel and generic signalling method is proposed that results in a significant reduction in signalling messages exchanged between a user equipment and the network over the air interface. Reduction of signalling messages in future mobile cellular systems is an important issue because of the current trend of deploying smaller cells while achieving higher than expected data area capacities. To demonstrate the effectiveness of this method within the standard constraints, some signalling procedures of the 3rd generation mobile standard, Universal Mobile Telecommunication System (UMTS), are investigated. In one application, the number of UMTS packet switch call setup messages was reduced down to three messages only. In such a scenario, measurements show that the gains in comparison with prior call setup is 61% in the duration of the call setup, 50% in the downlink processing delays, 93% in the downlink radio power transmission and 79% in the uplink radio power transmission.

Aggregated data from two double-blind base station provocation studies comparing individuals with idiopathic environmental intolerance with attribution to electromagnetic fields and controls.

Data from two previous studies were aggregated to provide a statistically powerful test of whether exposure to electromagnetic fields (EMFs) produced by telecommunication base stations negatively affects well-being in individuals who report idiopathic environmental illness with attribution to electromagnetic fields (IEI-EMF) and control participants. A total of 102 IEI-EMF and 237 controls participated in open provocation trials and 88 IEI-EMF and 231 controls went on to complete double-blind trials in which they were exposed to EMFs from a base station emitting either a Global System for Mobile Communication and Universal Mobile Telecommunications System or a Terrestrial Trunked Radio Telecommunications System signal. Both experiments included a comparison sham condition. Visual analog and symptom scales measured subjective well-being. Results showed that IEI-EMF participants reported lower levels of well-being during real compared to sham exposure during open provocation, but not during double-blind trials. Additionally, participants reported lower levels of well-being during high compared to low load trials and this did not interact with radiofrequency-EMF exposure. These findings are consistent with a growing body of literature indicating there is no causal relationship between short-term exposure to EMFs and subjective well-being in members of the public whether or not they report perceived sensitivity to EMFs.

Wide Area Monitoring System based on the third generation Universal Mobile Telecommunication System (UMTS) for event identification

Abstract Smart grids are one of the most essential infrastructure components in the world today. Power systems have been becoming more and more complex, as a result of a considerable variety of new components being added, such as High Voltage Direct Current (HVDC) and power electronic devices, and numerous recent technologies continually being put into application, such as distributed generation. In recent years, wide-area voltage and frequency measurements are used to identify different events that occur in power systems. One of the most important events is the generator trip identification. This event could be easily identified as a sudden drop in both the system voltage level and frequency. On the other hand, high-speed, reliable and scalable data communication infrastructure is crucial in both construction and operation of wide-area voltage and frequency measurements. Universal Mobile Telecommunication System (UMTS), the 3G standard for mobile communication networks, was developed to provide high speed data transmission with reliable service performance for mobile users. Therefore, UMTS is considered a promising solution for providing a communication infrastructure for WAMS. 3G based EWAMS (Egyptian Wide Area Monitoring System) is designed and implemented in Egypt through deployment a number of Frequency Disturbance Recorders (FDRs) devices on a live 220 kV/500 kV Egyptian grid to identify the location of tripped generator in the power system. WAMS systems are used for both off-line studies and real-time applications. An important feature of these systems is their ability to provide continuous dynamic measurements that are precisely time synchronized across the power system. With real-time WAMS, the continuous measurements feed out as a data stream which can be applied to on-line applications such as monitoring and control. This paper focuses on developing an efficient and reliable wide area voltage and frequency measurements through UMTS mobile communication technology in addition to the analysis these measurements using Principal Component Analysis (PCA) in order to determine a specific signature and properties for each tripped generator in the power system network.

Hybrid antenna arrays with non-uniform Electromagnetic Band Gap lattices for wireless communication networks

A method to design hybrid antenna configurations with very low profile, suitable for smart and Multiple Input–Multiple Output antenna systems is proposed. The antennas are incorporated with novel Electromagnetic Band Gap (EBG) surfaces with non-similar cells. These non-uniform EBG surfaces have been properly designed to cause focusing, of the incident waves, thus enhancing the characteristics of operation of antenna elements positioned in close proximity to the surface and also to increase the isolation between them. Theoretical analysis of the reflection mechanism of this type of lattices as well as the prediction of the resulting performance of the antenna is presented. All these considerations are validated with implementation and simulation of the hybrid structures inside the Universal Mobile Telecommunications System frequency band. The results show that increment of the gain and isolation between the antenna elements can be obtained. Moreover, results for the correlation coefficient between the elements, for Gaussian distribution of the incoming waves have been received and the tolerance of the antennas to the variation of the polarization characteristics of the incoming waves has been investigated. A Genetic Algorithm has been constructed and applied to find the proper geometry of the hybrid antennas in order the correlation coefficient to be minimized and get almost independent from the polarization of incident waves.

Joint minimization of uplink and downlink whole-body exposure dose in indoor wireless networks.

The total whole-body exposure dose in indoor wireless networks is minimized. For the first time, indoor wireless networks are designed and simulated for a minimal exposure dose, where both uplink and downlink are considered. The impact of the minimization is numerically assessed for four scenarios: two WiFi configurations with different throughputs, a Universal Mobile Telecommunications System (UMTS) configuration for phone call traffic, and a Long-Term Evolution (LTE) configuration with a high data rate. Also, the influence of the uplink usage on the total absorbed dose is characterized. Downlink dose reductions of at least 75% are observed when adding more base stations with a lower transmit power. Total dose reductions decrease with increasing uplink usage for WiFi due to the lack of uplink power control but are maintained for LTE and UMTS. Uplink doses become dominant over downlink doses for usages of only a few seconds for WiFi. For UMTS and LTE, an almost continuous uplink usage is required to have a significant effect on the total dose, thanks to the power control mechanism.

Outdoor-to-indoor Propagation Characteristics of 1900 MHz Signals in Macro-cellular Environments for GSM and UMTS Systems

Building penetration loss at 1900 MHz bands in suburban environment is evaluated. The measurements are conducted in real Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS) networks. Four buildings are studied aiming to provide first-order statistics of mobile signal coverage inside buildings. Results show that, on average, no significant signal band dependency has been confirmed. In general, UMTS-1900 MHz signals exhibit slight higher penetration loss values than GSM-1900 MHz signals. Analysis shows that the mean building penetration loss for all measured signals at the ground floor is about 16 dB. The standard deviation of building penetration loss was about 4.5 dB for wideband signals and 2.5 dB for narrowband signals. Results show also that, the average rate of change in building penetration loss with height is 0.95 dB per meter for wideband signals versus 0.65 dB per meter for narrowband signals.

Application Based Vertical Handoff Decision in Heterogeneous Network

Abstract The future generation of wireless system is expected to provide multimedia, multi class services any time anywhere with seamless mobility and Quality of service (QoS). In such environment, optimal vertical handoff is a challenging issue. Unnecessary handoff causes wastage of network resources and thus affects the QoS of network. In this paper, we have proposed the vertical handoff decision depends on coverage area of the network and the velocity of the mobile user. We have determined application-wise critical speed for particular coverage range of network during which handoff is beneficial. In our work, we have considered applications like HDTV, MPEG-4, and H.261 in heterogeneous network of UMTS (Universal Mobile Telecommunication System) and WLAN. The simulation is performed using Network Simulator NS-2 with NIST (National Institute of Standards and Technology) mobility module.

Reconfigurable PIFA with a parasitic strip line for a hepta‐band WWAN/LTE mobile handset

In this study, a reconfigurable planar inverted-F antenna (PIFA) with a parasitic strip line for a hepta-band wireless wide area network (WWAN)/long term evolution (LTE) mobile handset is proposed. The PIN diode is located between the end of the parasitic strip line and the protruded ground plane. Depending on the on/off-state of the PIN diode, the degree of coupling between the conventional PIFA and the parasitic line is controlled and the fundamental resonant frequency of the proposed antenna is adjusted. As a result, the fundamental resonant frequencies cover the (global system for mobile communication) GSM850 (824–894 MHz) and GSM900 (880–960 MHz) bands. By the parasitic strip line extended from the protruded ground plane, impedance matching at the higher-order modes (f 2 and f 3) is improved and the fourth resonant frequency f 4 is remarkably decreased. The high band of the antenna is formed by combining these three higher-order modes to cover the GSM1800 (1710–1880 MHz), GSM1900 (1850–1990 MHz), universal mobile telecommunication system (UMTS) (1920–2170 MHz), LTE2300 (2305–2400 MHz) and LTE2500 (2500–2690 MHz) bands.

Compact Dual Band Antenna for GSM1800/1900/ UMTS/ LTE/ UWB

In this paper, a UWB antenna with added lower band is presented. The proposed antenna is planar and its low profile makes it suitable for wireless applications. The design achieves good input impedance match from 1.8 - 11GHz making it suitable for Global System for Mobile communication (GSM 1800/1900: 1.71- 1.88GHz /1.85-1.99GHz), Universal Mobile Telecommunication System (UMTS: 1.92 - 2.17GHz), Long Term Evolution (LTE: 1.71 - 2.61GHz) and Ultra Wide Band (UWB: 3.1 - 10.6GHz) applications. The antenna is simulated using Ansys HFSS and CST microwave studio; fabrication is done using commercially available FR4 epoxy substrate of relative permittivity 4.4 and loss tangent 0.02.The overall antenna dimensions are 65mm x 50mm x 1.6mm.

Testing Radio Network Controller (RNC) Userplane Using Wireshark Tool

The telecommunication domain is developing very rapidly to meet the demand of day to day increase in data rate need. For example initially UMTS data rate was up-to 2 Mbps now it increased to 48 Mbps. This directly implies that the features that are developed are also increasing very rapidly. This increase in data can again degrade the network performance. These new features have to be tested accurately before releasing them on to the real world. In this paper we propose a simple and easy method to test RNC UserPlane functionality using wireshark tool. Functionalities imply that the RNC is working as per the standards. In other words user data which RNC receives should not be dropped due to RNC (or within some tolerance). This project is carried out at Nokia.

Optimising base station location for UMTS cellular networks

Rapid development of universal mobile telecommunication systems put demands on tools for assisting planning of cellular network infrastructure. The tools need to focus on critical issues in modern cellular networks and techniques used for previous generation system no longer serve useful. In this paper, an algorithm based on Branch & Bound approach is proposed for solving base station location problem, covering interference levels, traffic demands and power control mechanism. The efficiency of the algorithm is evaluated with respect to existing approaches for solving this problem – using the designed and implemented experimentation system.

Improving Handover and Drop-off Performance on High-Speed Trains With Multi-RAT

Provisioning commercial mobile telecommunications service on a high-speed train (HST) faces several challenges. In particular, when an HST quickly passes through the radio coverage of the base stations, frequent handovers may result in serious communication interruption. Methods such as the hierarchical two-hop network and the seamless dual-link handover scheme were proposed to address these challenges. This paper proposes the multiple radio access technology (multi-RAT) to resolve the HST handover issue, which allows the HST to simultaneously connect to two or more heterogeneous mobile networks (e.g., the Universal Mobile Telecommunications System and Long Term Evolution). With this approach, the handover process can be improved by keeping multiple heterogeneous network links of the HST at the same time and maintaining the connection through one link during the handover process of the other link. We show that multi-RAT can effectively enhance HST communications by reducing the impact of handover failure. This approach can work together with other solutions such as the dual-link scheme to further enhance the performance of the HST communications.

Exposure to electromagnetic fields in households--trends from 2006 to 2012.

This article is a follow-up study of extremely low-frequency electric and magnetic fields (ELF-EFs, ELF-MFs) and radiofrequency electromagnetic fields (RF-EMFs) using data collected in 2012 following earlier data sets from 2006 and 2009. Measurements were conducted in 219 bedrooms in Lower Austria. Out of these rooms 113 measurements were done in the same households in 2006, 2009 and 2012, and 106 were conducted in neighbouring buildings added in 2009 and newly recruited buildings in mainly urban areas in 2012. In revisited places the median of the ELF-EFs decreased from 23.20 V/m in 2006 to 13.90 V/m in 2012. The median of all-night measurements of ELF-MFs at 50 Hz decreased from 13.50 to 11.37 nT. The median of total RF-EMFs increased from 28.13 to 52.16 µW/m(2). Highest increases were found for universal mobile telecommunication system (UMTS) and wireless local area networks (WLAN). The analysis of all households showed higher total RF-EMFs in urban (median = 117.73 µW/m(2)) than in rural (median = 34.52 µW/m(2)) areas. Long-term evolution (LTE) in the 2600 MHz frequency range was detected at 17 locations with a maximum of 38.20 µW/m(2). Indoor RF-EMF sources resulted in decreased exposure in the frequency range of digital enhanced cordless telecommunications telephones (DECT) and increased exposure in the frequency range of WLAN.

Dual‐band CPW‐fed slot antenna with a pair of hook‐shaped slits

ABSTRACTIn this article, we present a new dual‐band coplanar waveguide‐fed slot antenna for wireless communication systems. The proposed antenna is fabricated on an FR4 substrate with dielectric constant of 4.4. Configuration of the antenna structure consists of modified radiating stub with a pair of hook‐shaped slits and slotted ground plane where operates over a very wide bandwidth and improves the impedance matching. By cutting a pair of modified hook‐shaped slit at the radiating stub, a good dual‐band can be achieved. The measured impedance bandwidth of the proposed antenna for 10 dB return loss is from 1.75 to 2.42 GHz and 3.51 to 3.72 GHz, covering the major wireless communication bands like 1.8 GHz digital communication service, 1.9 GHz personal‐mobile communication service, 2.2 GHz universal mobile telecommunications system, 2.3 GHz wireless broadband, 2.4 GHz wireless local area network, 3.5 GHz worldwide interoperability for microwave access, and so forth. Simulated and experimental results obtained for this antenna show that the proposed slot antenna has a good radiation behavior. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:172–174, 2015

Performance of opportunistic fixed-beam spatial multiplexing in OFDMA uplink

Adaptive spatial multiplexing (SM) Multiple Input Multiple Output (MIMO) techniques enhance the spectral efficiency of wideband wireless communications in favorable radio channel conditions. In this study, we show the benefits of combining a traditional fixed-beam scheme and multiuser opportunistic radio resource allocation in space-time-frequency domains. This combining is feasible in wideband Orthogonal Frequency Domain Multiple Access (OFDMA) systems such as the Universal Mobile Telecommunications System (UMTS) Long Term Evolution (LTE). This study brings novel knowledge which indicates that an orthogonal fixed beam approach benefits from opportunistic radio resource allocation clearly more than a conventional antenna domain approach in frequency-selective radio channels. It was found out that the fixed beam radio link performance is enhanced in wideband adaptive radio links due to the fact that orthogonal beams reduce correlation between the MIMO channels in the allocated sub-bands. Moreover, beamforming gains bring higher Eigenvalues of the MIMO channel matrix in the opportunistically selected sub-bands. It is shown that the fixed beam deployment changes the distribution of the MIMO channel correlation values and Eigenvalues in a manner which enhances opportunistic multiuser gains in wideband time-frequency-selective MIMO radio channels. Simulation results with 2 × 2 spatial multiplexing in an OFDMA uplink indicate that the proposed beam domain scheme gives up to 80% data throughput gain over the corresponding antenna domain scheme in a pedestrian microcell environment.

Compact and closely spaced tunable printed F‐slot multiple‐input–multiple‐output antenna system for portable wireless applications with efficient diversity

In this work, miniaturised tunable two-antenna multiple-input–multiple-output (MIMO) systems composed of printed F-slot shaped are developed to operate in the global positioning system (GPS), personal communication system (PCS), distributed control system and Universal Mobile Telecommunications System bands. The two-element MIMO antenna occupies a volume of 50 × 37.5 × 1.6 mm3, and is printed on an FR4 substrate. Initially, the frequency tunability of the MIMO antennas was verified by lumped capacitors with values between 0.75 to 2.75 pF to achieve a tuning range from 1.55 to 2.07 GHz while the low mutual coupling between the radiators was accomplished by adding an I-shaped branch to a cut-away ground plane. The two antennas are then loaded with varactors to simultaneously achieve miniaturisation and tunability. Simulation and measurement results demonstrate the successful implementation of a tunable MIMO with coupling reduction mechanism for a portable handheld wireless transceiver. The channel capacity of the proposed antenna is investigated and found to be close to that of a un-correlated system with efficient diversity in which the mutual coupling across the full bandwidth was better than −13 dB. Owing to the compact size and ease of manufacture, the proposed antennas can be a promising solution for adaptive MIMO systems in handheld devices.

Development of an RF-EMF Exposure Surrogate for Epidemiologic Research from Modelling, Personal Measurements and Operator Data

Introduction Exposure to radiofrequency electromagnetic fields (RF-EMF) is ubiquitous and thus to study potential effects of RF-EMF the exposure assessment is a crucial part. The aim was to develop an integrative exposure surrogate measure to estimate both, whole-body and brain exposure. Methods Far-field exposure to fixed site transmitters is modelled using a geospatial propagation model. Contribution of far-field exposure from WLAN (Wireless Local Area Network) and DECT (Digital Enhanced Cordless Telecommunications) base stations have been identified by means of regression models from personal measurements. Predictors of the near-field exposure were identified from the literature. To evaluate the impact of differences in the power control of GSM (Global System for Mobile Communications) and UMTS (Universal Mobile Telecommunications System) mobile phones, personal measurement data was related to mobile phone operator data. Results Based on personal measurements from 71 adolescents carrying an exposimeter between 42 and 121 hours and filling out an activity diary, the following far-field WLAN and DECT exposure predictors have been identified: WLAN at school, WLAN at home and not switching off the base station during night and DECT phone base station placed in the bedroom, the living room or the kitchen. For the uplink far-field exposure the number of smartphones used by the family and the time spent in trains and buses were relevant predictors. We found indication that type of network is relevant since duration of GSM calls was associated with personal uplink exposure levels whereas duration of UMTS calls was not. Conclusion The preliminary results indicate only a few relevant exposure predictors. Although the proposed approach is proven to be feasible to combine near- and far-field exposure sources to an integrative whole-body and brain exposure value, more data is needed to obtain more robust and significant estimates.

A multimedia transmission control algorithm based on cross-layer design in UMTS networks

The performance in the air interface of 3G/UMTS (Universal Mobile Telecommunications System) network is enhanced by the introduction of many advanced functionalities including ARQ (Automatic Repeat Request), HARQ (Hybrid ARQ) and AMC (Adaptive Modulation and Coding). Most existing TFRC (TCP-Friendly Rate Control)-based algorithms designed for wired-wireless heterogeneous networks fail to adapt to these advanced functionalities which results in degradation of performance. This paper proposes a novel cross-layer streaming transmission control algorithm WATC (Wireless-loss Aware Transmission Control) which makes use of the ARQ information to estimate the quality of wireless channels and improve the measurement of delay with the help of RLC (Radio Link Control) sublayer. WATC distinguishes wireless loss from congestion loss by the estimation of the quality of wireless channel and adjusts the sending rate according to the quality of wireless links and the tendency of delay variation. Simulation results show that WATC outperforms existing TFRC-like schemes in terms of loss rate control and throughput, while maintaining high throughput and fairness in multi-flow scenarios.

Performance of CS Fallback for Long Term Evolution Mobile Network

When a mobile operator migrates its network from the third generation (3G) system to Long Term Evolution (LTE), both 3G and LTE will coexist for a period of time. Since the 3G circuit-switched (CS) voice mechanism is more mature and available than that for the LTE Voice over Internet Protocol (VoIP), the operator may consider CS fallback (CSFB) as a solution for providing reliable voice calls. According to the 3G Partnership Project (3GPP) CSFB procedure, when a mobile user in the LTE network has an incoming or an outgoing call, the user equipment (UE) falls back from LTE to Universal Mobile Telecommunications System (UMTS). When the call is complete and released, the UE immediately returns to LTE. If the next activity for the UE is another voice call, immediately switching from UMTS to LTE may not be efficient. In this case, the UE has to perform another CSFB. To resolve this issue, we suggest delaying the returns to avoid unnecessary CSFBs, which is called delayed return (DR). Based on the measurements from the real UMTS and LTE networks, we develop an analytic model for investigating the performance of the CSFB with DR. This paper indicates that the DR scheme can effectively reduce the CSFB costs by up to 60%.