Universal Mobile Telecommunications System System Research Articles

Implementation of RF Band-Pass Filter on UMTS Systems to Improve Quality of Service

A large number of cellular operators in an area causes high interference effects. One indicator is the problem with received total wideband power (RTWP) found in a universal mobile telecommunication system (UMTS). High RTWP is one of the causes of a decrease in the quality of service (QoS) in cellular communication networks. To solve this problem, an RF band-pass filter device can be implemented on a UMTS system, where RF band-pass filters have been designed and tested in previous studies. In this research, the RF band-pass filter was installed between the BTS node and bottom jumper. After implementing it, QoS measurements with the Huawei M2000 application and Drive Test were carried out. The QoS analysis included RTWP, Circuit-Switched access rate, Packet-Switched access rate, and Received Signal Code Power (RSCP) value. The results show that the RTWP value decreases, while the CS access rate, PS access rate, and RSCP value increase. These results indicate that QoS on the UMTS increases.

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.

Evaluation of Security Attacks on UMTS Authentication Mechanism

In this study security of internet access over the Third Generation (3G) telecommunication systems is considered and Universal Mobile Telecommunications System (UMTS) is selected as the most popular system among 3G systems. The study then focuses on network access security mechanism of UMTS, called Authentication and Key Agreement (AKA). In addition, twenty types of important attacks and threats in UMTS system are presented and classified based on three major security factors; authentication, confidentiality, and data integrity. The evaluations finally show that the authentication factor is more interesting than other factors for hackers. Then, we describe four attacks named; man-inthe-middle, denial of service, identity catching, and redirection as the most significant attacks against authentication mechanism. Furthermore, we provide some solutions and methods to improve AKA mechanism and prevent these attacks in UMTS system.

A Study on the Effect of UWB Interference on Downlink UMTS System

In this paper, we evaluate the performance of UMTS (Universal Mobile Telecommunication System) downlink system in vicinity of UWB system. The study is achieved via simulating a scenario of a building which is located within UMTS cell borders and utilizes from both UMTS and UWB appliances. The simulation results show that the UMTS system is considerably affected by the UWB interference. However, in order to battle this interference and achieve reasonable BER (Bit Error Rate) of 10−4, we found that it is very necessary to carefully raise the UMTS base station transmitted power against that of UWB interferer. So, the minimum requirements for UMTS system to overcome UWB interference are stated in this work.

A Planar Quasi-Yagi For Next Generation Wireless Communication Systems

UMTS (Universal Mobile Telecommunications System) technology is one of the third-generation (3G) cell phone technologies, which is also being developed into a 4G technology. Although UMTS2001 is the most widely-deployed UMTS band, some countries utilize 1900 MHz instead. Besides, the co-existing GPS (Global Positioning System) operates at the frequency of 1575 MHz. Thus, a desirable antenna in UMTS systems needs to cover both of two bands in order to operate in various devices. This paper will propound an antenna covering the range of frequencies from 1.53 GHz to 2.53 GHz that includes 1.575 GHz, 1.8 GHz, 1.9 GHz ,and 2.1 GHz. The developed quasi-Yagi antenna has a simple-low profile and achieves a bandwidth of 48%, a front- to- back ratio of 19 dB, a gain of 6dBi, and an efficiency of better than 78% at 2.1GHz. In this paper, the study on effects of parameters of the antenna is also investigated to achieve optimal model.

About the location of base stations for a UMTS system: Analytical study and simulations

One of the first decisions that a radio network designer must take is the location of base stations and the distance between them in order to give the best coverage to a region and, possibly, to reduce deployment costs. In this paper, the authors give an insight to this matter by presenting a possible solution to a real problem: Planning the base stations layout for a universal mobile telecommunications system (UMTS) in the city of Barcelona. At the basis of this problem, there is the interdependence between coverage and capacity in a wideband-code division multiple access (W-CDMA) system, which is a new element in the planning of BS layout for mobile communications. This aspect has been first treated with an analytical study of the cell coverage range for a specific environment and service. The achieved results have been checked with the help of snapshot simulations together with a geographical information system (GIS) tool incorporated in the simulator that allows to perform analysis and to visualize results in a useful way. By using the simulator, it is also possible to study a more complex environment, that of a set of base stations providing multiple services to a large number of users.

On the Impact of Soft Handoff Threshold and Maximum Size of the Active Group on BS Transmit Power in the UMTS System

This paper investigates the effect of two control parameters of the Universal Mobile Telecommunications System (UMTS) handoff algorithm on the total peak base station (BS) transmit power required per mobile station (MS) to satisfy a prescribed outage probability. Denoting the set of BSs supporting an MS in soft handoff (SH) as the active group, the first parameter n is the maximum allowed size of the active group. The second, denoted /spl tau/, is the upper limit on the difference between the path loss of the dominant BS and that of any other member of the active group, where the term "dominant" refers to the BS with the lowest path loss to the MS. It was assumed that the MS is equipped with a Rake receiver capable of performing "maximal ratio combining" of the signals it receives from the transmitting BSs. General analytical derivations along with results derived for specific situations through numerical integration are presented.

Performance evaluation of a novel scheme for QoS provision in UTRA TDD

Satisfying Quality of Service (QoS) requirements, is one of the main goals of UMTS (Universal Mobile Telecommunications System), which represents a major 3G wireless technology. The Internet services have a significant impact on the radio frequency network over which resources are particularly scarce. To guarantee different QoS requirements for diverse traffic types, while at the same time maintaining fair and high utilization of wireless resources, an efficient resource management, specifically the slot allocation and resource reservation during admission and handoffs, is essential for UMTS systems. In this paper, we propose a novel scheme for slot allocation and resource reservation for handoff using the concepts of traffic asymmetry, signal to interference ratio, and cell differentiation. The study of the effects of this scheme on the quality of service provision is accomplished through a modeling of the main QoS parameters and a simulation that gives an evaluation of the system behavior.

HBT power amplifier with dynamic base biasing for 3G handset applications

In this paper, a performance optimization of a digital signal processing driven and dynamically biased 3G handset's power amplifier technique is proposed, simulated and implemented. This technique uses a new dynamically base biasing heterojunction bipolar transistor which reduces the dc power consumption at low level drive and at the same time compensates the nonlinear distortion at high power drive of the PA in the transmitter of a universal mobile telecommunications system (UMTS) system with a high integrability. With the UMTS system, at low level drive, the dc power reduction is about 60% and at high emission power, the nonlinearity of the PA is corrected to respect the adjacent channel power ratio (ACPR) and error vector magnitude constraints imposed by the UMTS. With our system, the ACPR and efficiency of the power amplifier are improved, respectively, by 5 dB and 8%.

Urban Wide-Band Measurement of the UMTS Electromagnetic Environment

Measurements of impulsive noise in the universal mobile telecommunications system (UMTS) electromagnetic environment in urban areas have been conducted and its effect on the UMTS system is analyzed. An impulsive noise-measurement system for the UMTS frequency band has been designed and built, which meets and improves the main features of classical equipments used to measure noise, offering inphase and quadrature outputs simultaneously. This measurement system was carefully calibrated before a measurement campaign was conducted in an urban environment to get impulsive noise statistics. Results show that noise pulses may have high power, long duration, and high repetition rate, so the performance of UMTS could be significantly reduced.

Measurement techniques for UMTS signals radiated by radio base stations.

In the most European countries radio coverage for the third radio mobile generation. i.e, the UMTS (Universal Mobile Telecommunications System), will soon be started. In the past few years, national laws specifying limits on exposure to electromagnetic fields have drawn much attention on electromagnetic test bed and measurement procedures for radio mobile equipment/systems. An overview is given of the UMTS system, showing the main characteristics of the radio access network UTRAN (UMTS Terrestrial Radio Access Network). An analysis is also provided as to the measurement techniques and related instrumentation for the electric field intensity radiated by a UMTS radio station.