GPS接收机应用于手机中所遇到的射频干扰

将GPS接收机嵌入到手机硬件中,GPS接收频率将与手机中其它射频源共存.这些射频源包括GSM,UMTS,WLAN和Bluetooth.指出这些射频源对GPS接收信号的干扰程度,以明确哪种射频源对GPS接收机的阻塞影响最大,成为提出相应的解决方案是关键.验证方法主要是由Texas Instrument提供的GPS评估板接收来自GPS卫星模拟器发出的GPS信息,由具备GSM,UMTS,WLAN,Bluetooth功能的手机分别对GPS评估板发出不同的射频传导信号.结果证明:主要验证了UMTS1 900 MHz作为手机发射源时,对GPS接收机的阻塞影响最大,对改善GPS接收机带通滤波器的性能,为抑制UMTS信号起到很好的作用.     

An A/D Converter for Multimode Wireless Receivers, Based on the Cascade of a Double-Sampling$SigmaDelta$Modulator and a Flash Converter

This work proposes an architecture for an analog-to-digital converter intended for a multimode wireless receiver. The architecture is based on the cascade of a single-bit 2-1 sigma–delta modulator and a 4-bit flash converter. Furthermore such an architecture is mapped in a modular implementation, which allows to easily reconfigure modulator order, oversampling ratio and equivalent number of bits of the internal quantizer. As a consequence, the proposed converter can fulfill the requirement of a wide range of standards: Global System for Mobile Communications (GSM), Bluetooth, universal mobile telecommunications system (UMTS), and wireless local area network (WLAN)a. The paper discusses extensively the effects of circuit nonidealities on the converter performance, in order to single out the most suited setup for the programmable parameters and to demonstrate the practical feasibility of the proposed system. The converter figures of merit have been quantified by means of transistor-level and behavioral simulations: the achieved dynamic range is 85, 72, 62, and 59 dB for GSM, Bluetooth, UMTS, and WLANa, respectively. The corresponding power consumption is 4.6, 5.5, 7.4, and 18.9 mW.     

Potential fraudulent usage in mobile telecommunications networks

This paper investigates the fraudulent usage of mobile telecommunications services due to cloned subscriber identity modules (SIMs). In GSM or the Universal Mobile Telecommunication System (UMTS), a mobile phone or mobile station uses its SIM to gain network access through authentication. If the SIM of a legal user is cloned, then the cloned SIM can be used for GSM/UMTS authentication and fraudulent usage may occur. Under the existing GSM/UMTS mobility management and call setup procedures, we show how quickly the fraudulent usage can be detected. We also propose a simple solution to speed up the detection of potential fraudulent usage.     

UMTS security

The Universal Mobile Telecommunications System (UMTS) is one of the new 'third generation' mobile cellular communication systems. UMTS builds on the success of the 'second generation' GSM system. One of the factors in the success of GSM has been its security features. New services introduced in UMTS require new security features to protect them. In addition, certain real and perceived shortcomings of GSM security need to be addressed in UMTS. This paper surveys the major security features that are included in the first releases of the UMTS standards.     

Multi-domain architecture for policy management inumts ip multimedia subsystem

The Universal Mobile Telecommunications System (UMTS) offers IP-based multimedia applications and services with end-to-end Quality of Service (QoS) guarantee. The key component providing these services is the IP Multimedia Subsystem (IMS) that uses Service-Based Local Policy (SBLP) management for QoS control. To support end-to-end QoS, the UMTS IMS network should be scalable, reliable and flexible in policy deployment and enforcement, characteristics that are not found in single-domain policy architecture. A hybrid policy architecture is proposed, in which a hierarchical architecture is applied to the multi-domain environment in a single operator UMTS IMS network, while a peering architecture is employed in a multi-operator UMTS IMS network. The proposed multi-domain policy architecture potentially minimizes the session setup delay and policy exchange traffic while maximizing network scalability.     

UMTS — the mobile part of broadband communications for the next century

This paper outlines the path from developing broadband ISDN/ATM systems towards the European vision of the next generation mobile system — Universal Mobile Telecommunications System (UMTS).The capabilities of UMTS in terms of services and features compared to the second generation mobile system GSM, and the network technologies behind N-ISDN and B-ISDN, are discussed with proposals for technical developments to satisfy the UMTS requirements. The UMTS radio interface aspects are described and considerations on the network requirements to support these radio aspects are discussed.The requirements within the network for control, switching and transport to support the mobility, service and interconnecting network aspects of UMTS are outlined in conjunction with the technical solutions currently under discussion and some latest thoughts on a potential high-level architecture     

Location-Based Services — An Overview of the Standards

This paper traces the history of location-based service (LBS) standards that arose from North American requirements in the work on GSM standards in the late 1990s. It also describes how interest in GSM/UMTS outside Europe led to the creation of the Third Generation Partnership Project (3GPP) for developing UMTS standards (which include standards for the 3G mobile Internet). In addition, the paper covers the role of other standards bodies and interest groups involved in the creation of LBS standards such as the new Open Mobile Alliance.Different location methods for detecting the position of mobiles are described and a summary of the current work in 3GPP on LBS-based services and architecture for UMTS is given. The paper also covers work on wireless access protocols in the old WAP Forum     

UMTS overview

The Universal Mobile Telecommunications System (UMTS) as specified by the Third Generation Partnership Project (3GPP) was formally adopted by the ITU as a member of its family of IMT-2000 Third Generation Mobile Communication standards in November 1999. This paper provides some background to the UMTS standard and an overview of the system architecture. Some information about the current status of technology trials is provided as well as predictions for the services that future UMTS networks are likely to deliver to the end user     

An improved handover algorithm based on signal strength plus distance for interoperability in mobile cellular networks

In future generation mobile cellular systems, position location of mobile terminal is expected to be available. In this paper, we propose an initiation algorithm for intersystem handover based on the combination of position location of mobile terminal and the absolute signal strength thresholds. Global System for Mobile communication (GSM) and Universal Mobile Telecommunication Systems (UMTS) networks are considered for interworking. The proposed algorithm reduces the handover rate by around 50% and thus improves the network resource efficiency as compared to that based on signal strength thresholds only.     

Mobile next-generation networks

Mobile next-generation networks (NGNs) are a necessary element in reaching the goal of truly ubiquitous computing. The Universal Mobile Telecommunication System, the third-generation mobile service concept, is a technology step to mobile NGNs. We can view NGNs as a merger of the Internet and intranets with mobile networks and with media and broadcast technologies. The Universal Mobile Telecommunication System (UMTS) is-from a radio perspective-a third-generation cellular technology, which is defined by the International Telecommunication Union (ITU) in its IMT-2000 framework (2001). From a conceptual point of view, it represents a technology step to mobile NGNs' facilitating ubiquitous computing. Researchers conceived UMTS to combine Internet protocol (IP) and mobile technologies to offer personal communication and personalized content everywhere. Its goal is to apply Internet protocols for mobile services control and end-to-end applications. By analyzing the trends of key technologies, we can see how they drive the evolution of the Internet and mobile communications toward mobile NGNs. In this article, I describe the IP-based approach of UMTS for the provision of mobile multimedia services. The integration of WLAN into the UMTS architecture could indicate that the field is moving toward separating mobile and fixed Internet.     

T-dipole arrays for mobile applications

This paper describes the work of the Antenna Department of France Telecom R&D (Research and Development) - formerly CNET (Centre National d'Etudes des Telecommunications) - on base-station antennas. The goal of this development work was to study new signal processing systems, or to characterize propagation within the frequency band of the following new wireless systems: GSM, Global System for Mobile Communications; UMTS, Universal Mobile Telecommunications System; HIPERLAN, high performance radio local area network. However, the results presented concern only the antennas, in many different configurations. All of them are based on the T-dipole antenna.     

Multiband folded planar monopole antenna for mobile handset

This paper introduces a folded planar monopole antenna, which has a very low profile of about one twentieth of the wavelength of the lowest operating frequency. The effect is achieved by using a bended rectangular radiating patch and an inverted L-shape ground plane. The proposed antenna can be used in multiband operation, with omnidirectional radiation patterns for all operating bands. Its impedance bandwidth, determined by 10 dB return loss, covers almost all present wireless communication systems: Global System for Mobile Communication (GSM), Digital Communication System (DCS), Personal Communication System (PCS), Universal Mobile Communication System (UMTS), and Industrial Science Medical (ISM) band. This paper presents the design and experimental results of the proposed antenna. Moreover, the study also investigates the tuning effects of the geometry parameters on impedance matching.     

UMTS architecture for integrating terrestrial and satellite systems

This architecture proposal for the Universal Mobile Telecommunication System harmonizes several approaches to the evolving European Union mobile-systems standard. The architecture accommodates both satellite and terrestrial networks and allows a smooth transition from existing systems to UMTS     

A single-chip multimode receiver for GSM900, DCS1800, PCS1900, and WCDMA

A single-chip, multimode receiver for GSM900, DCS1800, PCS1900, and UTRA/FDD WCDMA is introduced in this paper. The receiver operates at four different radio frequencies with two different baseband bandwidths. The presented chip uses a direct-conversion architecture and consists of a low-noise amplifier (LNA), downconversion mixers with on-chip local-oscillator I/Q generation, channel selection filters, and programmable gain amplifiers. In spite of four receive bands, only four on-chip inductors are used in the single-ended LNA. The repeatable receiver second-order input intercept point (IIP2) of over +42 dBm is achieved with mixer linearization circuitry together with a baseband circuitry having approximately +100-dBV out-of-band IIP2. The noise figure of the SiGe BiCMOS receiver is less than 4.8 dB in all GSM modes, and 3.5 dB in WCDMA. The power consumption from a 2.7-V supply in all GSM modes and in WCDMA mode is 42 and 50 mW, respectively. The silicon area is 9.8 mm/sup 2/ including the bonding pads.     

Security and Authentication in the Mobile World

Mobile systems are evolving into data centric, packet switched,multiacess networks. New types of security threats are emerging in thesenew networks. From the user point of view a seamless solution for thesethreats is required. This paper presents a vision of network convergenceand its implications to authentication and authorization solutions.Security requirements are discussed and current authentication solutionsin GSM, UMTS and operator wireless local area networks (OWLAN) areintroduced. All-IP multimedia session security is discussed.Implications of AdHoc network architecture into security requirement arediscussed.     

The Universal Mobile Telecommunication System

The concepts, requirements, and technologies of Europe's third generation mobile communication system-the Universal Mobile Telecommunications System (UMTS)-are discussed. The cellular architecture, radio resource, adaptive resource allocation and handover enabling techniques for realizing an effective UMTS access network are described. The modulation schemes, multiple access methods, and duplexing methods used in the third generation mobile system's flexible radio interface are also described. The architecture, mobility support, and protocol development of the UMTS fixed network are outlined     

Die Vision UMTS

The Universal Mobile Telecommunications System UMTS is the European vision of a 3^rd generation mobile telecommunications system. UMTS will carry on the world-wide success of the European 2^nd generation system, GSM, which now (in February 1998) has 66 million subscribers and 239 operators. The evolution towards UMTS will show both: On the one hand a new air interface will allow multiple users to communicate with several media simultaneously, i.e. transmitting and receiving voice, data, text, images, audio and video at a maximum data rate of 2 Mbit/s. On the other hand enhanced, intelligent networks will support the mobility of users with UMTS-, GSM- and cordless phones. UMTS will be a major contribution to the convergence of telecommunications, broadcasts and computers, setting a milestone on our way towards a global information society.     

An Efficient Mechanism for UMTS Multicast Routing

In this paper, we present a novel scheme for the multicast transmission of data over Universal Mobile Telecommunications System (UMTS) networks. Apart from the normal multicast transmission over UMTS, we consider the handling of exceptional cases caused by user mobility scenarios. The proposed scheme is in accordance with the current specifications of the Multimedia Multicast/Broadcast Service (MBMS) defined by the 3rd Generation Partnership Project (3GPP) and introduces minor modifications in the UMTS architecture and the mobility management mechanisms. The proposed scheme is implemented as an ns-2 network simulator module. The performance of the proposed scheme is validated and analyzed through ns-2 simulation experiments. This new module can be employed to investigate various aspects of UMTS multicast. Furthermore, in order to further highlight the contribution of our mechanism, we have implemented two multicast congestion control mechanisms for UMTS and we have measured their performance for MBMS transmissions.