Showing papers on "GSM published in 2003"

Challenges in the migration to 4G mobile systems

Abstract: With the rapid development of wireless communication networks, it is expected that fourth-generation mobile systems will be launched within decades. 4G mobile systems focus on seamlessly integrating the existing wireless technologies including GSM, wireless LAN, and Bluetooth. This contrasts with 3G, which merely focuses on developing new standards and hardware. 4G systems supports comprehensive and personalized services, providing stable system performance and quality service. However, migrating current systems to 4G presents enormous challenges. In this article, these challenges are discussed under the headings of mobile station system, and service aspects. Proposed solutions to the research problems in each aspect are also examined.

Instant ciphertext-only cryptanalysis of GSM encrypted communication

Abstract: In this paper we present a very practical ciphertext-only cryptanalysis of GSM encrypted communication, and various active attacks on the GSM protocols. These attacks can even break into GSM networks that use “unbreakable” ciphers. We describe a ciphertext-only attack on A5/2 that requires a few dozen milliseconds of encrypted off-the-air cellular conversation and finds the correct key in less than a second on a personal computer. We then extend this attack to a (more complex) ciphertext-only attack on A5/1. We describe new attacks on the protocols of networks that use A5/1, A5/3, or even GPRS. These attacks are based on security flaws of the GSM protocols, and work whenever the mobile phone supports A5/2. We emphasize that these attacks are on the protocols, and are thus applicable whenever the cellular phone supports a weak cipher, for instance they are also applicable using the cryptanalysis of A5/1. Unlike previous attacks on GSM that require unrealistic information, like long known plaintext periods, our attacks are very practical and do not require any knowledge of the content of the conversation. These attacks allow attackers to tap conversations and decrypt them either in real-time, or at any later time. We also show active attacks, such as call hijacking, altering of data messages and call theft.

Instant ciphertext-only cryptanalysis of GSM encrypted communication

Abstract: In this paper we present a very practical ciphertext-only cryptanalysis of GSM encrypted communication, and various active attacks on the GSM protocols. These attacks can even break into GSM networks that use unbreakable ciphers. We describe a ciphertext-only attack on A5/2 that requires a few dozen milliseconds of encrypted off-the-air cellular conversation and finds the correct key in less than a second on a personal computer. We then extend this attack to a (more complex) ciphertext-only attack on A5/1. We describe new attacks on the protocols of networks that use A5/1, A5/3, or even GPRS. These attacks are based on security flaws of the GSM protocols, and work whenever the mobile phone supports A5/2. We emphasize that these attacks are on the protocols, and are thus applicable whenever the cellular phone supports a weak cipher, for instance they are also applicable using the cryptanalysis of A5/1. Unlike previous attacks on GSM that require unrealistic information, like long known plaintext periods, our attacks are very practical and do not require any knowledge of the content of the conversation. These attacks allow attackers to tap conversations and decrypt them either in real-time, or at any later time. We also show active attacks, such as call hijacking, altering of data messages and call theft.

Method of seamless roaming between wireless local area networks and cellular carrier networks

Abstract: A scheme that enables seamless roaming between the WLAN and the cellular carrier network by enabling a user that originates a call in the WLAN and happens to go outside the range of the WLAN to automatically switch over to the cellular carrier network without losing connection with the other party. This solution assumes that the mobile device has the capability to operate in at least two modes that include the WLAN mode and one of the cellular carrier modes, such as the GSM, IS-95 CDMA, IS-136 TDMA, and iDEN.

Analog laser predistortion for multiservice radio-over-fiber systems

Abstract: We have developed some low-cost predistortion circuits to compensate second- and third-order laser distortions in multiservice radio-over-fiber industrial systems. Depending on the predistorter configuration implemented, average reductions of 10-15 dB and of 8-10 dB have been observed in the laser second- and third-order distortions, respectively, within the cellular bands relevant to the European TETRA, GSM, and DCS standards. In particular, the development of the prototypes here illustrated is based on a new and original procedure that formalizes and suitably integrates in a sinergistic way modeling, design, and experimental activities.

A software-defined communications baseband design

Abstract: Software-defined radios offer a programmable and dynamically reconfigurable method of reusing hardware to implement the physical layer processing of multiple communications systems. An SDR can dynamically change protocols and update communications systems over the air as a service provider allows. In this article we discuss a baseband solution for an SDR system and describe a 2 Mb/s WCDMA design with GSM/GPRS and 802.11b capability that executes all physical layer processing completely in software. We describe the WCDMA communications protocols with a focus on latency reduction and unique implementation techniques. We also describe the underlying technology that enables software execution. Our solution is programmed in C and executed on a multithreaded processor in real time.

Method of performing inter-RAT measurement for a handover from NB-TDD to GSM

Abstract: A method of performing an inter-RAT measurement for a handover from NB-TDD to GSM is provided A UE, as it moves from an NB-TDD Node B to a GSM cell, receives a measurement control message from the NB-TDD Node B The UE then measures the strength of a signal received from the GSM cell and verifies its identification for a predetermined measuring time If the UE successfully verifies the identification of the GSM cell for the measuring time, it reports the signal strength measurement and the verified GSM cell identification to the NB-TDD Node B If the UE fails to verify the identification of the GSM cell for the measuring time, it reports only the signal strength measurement to the NB-TDD Node B

Method for performing inter system handovers in mobile telecommunication system

Abstract: An inter system handovers in a mobile telecommunication system is performed when a dual mode user equipment (UE) covered by both GSM/GPRS network and UMTS network connects a dedicated channel and sets up a call in a BSS region where the GSM/GPRS provides coverage, and then moves to a UTRAN (UMTS Terrestrial Radio Access Network) where the UMTS provides coverage, wherein the method includes the steps of: if the dual mode UE receives an inter system handover command, i.e. from the BSS to the UTRAN, requesting GSM/GPRS data link layer to suspend a GSM/GPRS data link by a sublayer RR of GSM/GPRS network layer in the UE, requesting a GSM/GPRS physical layer to release a physical channel of the GSM/GPRS, and sending the inter system handover command to the UTRAN for authorizing a sublayer RRC of UMTS network layer in the UE to continue a call; requesting, at the RRC in the UE, a UMTS physical channel to be configured as a UMTS physical channel, and monitoring if the UMTS physical layer succeeds to have the configuration of the UMTS physical channel as requested; if the UMTS physical layer succeeds to have the configuration of the UMTS physical channel, requesting, at the RRC in the UE, a UMTS data link layer to configure a UMTS data link, and conveying information to the UTRAN through a UMTS channel that the handover between systems from the BSS to the UTRAN has been successfully performed; and sending, at the RRC, a GSM/GPRS resource release message to RR/GRR, thereby resetting the GSM/GPRS physical layer and the GSM/GPRS data link layer.

Design of a multiband internal antenna for third generation mobile phone handsets

Abstract: A multiband internal antenna is introduced. The antenna consists of a driven meander-line element and two parasitic elements. The design is particularly unique since it supports the third generation mobile phone handsets where multiband operation is greatly desired. The proposed antenna operates effectively in the AMPS 800 (824-894 MHz), GSM 900 (880-960 MHz), and GSM 1900 (1850-1990 MHz) bands within 2.5:1 voltage standing wave ratio (VSWR). Detail design criteria with respect to geometrical parameter variation are given. Experimental data (VSWR and pattern) obtained from a laboratory prototype are also presented.

Energy efficient object location reporting system

Abstract: An object location tracking device (10) is constructed to include a battery (10D), a movement sensor (10E), a GSM engine (10A) and a radio frequency (RF) transceiver (10B). The tracking device, in response to the movement sensor sensing a cessation of movement, transmits a message that results in initiating a location determination operation via the RF transceiver to a GSM network (12). The tracking device may transmit data representing its current location to the GSM network. The tracking device thereafter places at least the GSM engine into a reduced battery power consumption mode of operation. In one embodiment the message transmitted by the location tracking device is, as examples, a SMS message or a GPRS message that contains an alpha string that requests the location application server to cause the GSM network to initiate a Mobile Terminated Location Request operation for the tracking device.

Mobility modelling and trajectory prediction for cellular networks with mobile base stations

Abstract: This paper provides mobility estimation and prediction for a variant of GSM network which resembles an adhoc wireless mobile network where base stations and users are both mobile. We propose using Robust Extended Kalman Filter (REKF)as a location heading altitude estimator of mobile user for next node (mobile-base station)in order to improve the connection reliability and bandwidth efficiency of the underlying system. Through analysis we demonstrate that our algorithm can successfully track the mobile users with less system complexity as it requires either one or two closest mobile-basestation measurements. Further, the technique is robust against system uncertainties due to inherent deterministic nature in the mobility model. Through simulation, we show the accuracy and simplicity in implementation of our prediction algorithm.

Method for handling inter-RAT measurement and report in a dual-mode user equipment

Abstract: Disclosed is a method for handling inter-RAT cell measurement in a dual-mode UE in a connected mode, which supports both GSM/GPRS (Global System for Mobile communication/General Packet Radio Service) RAT (Radio Access Technology) and UMTS (Universal Mobile Telecommunications System) RAT. A UTRAN (UMTS Terrestrial Radio Access Network) of the UMTS RAT transmits a measurement control message to a URRC (UMTS Radio Resource Control) of a UMTS network layer in the UE. Upon receiving the measurement control message, the URRC sends a measurement request for GSM cells to an RR/GRR (Radio Resource/GPRS Radio Resource) of a GSM/GPRS network layer. The RR/GRR activates a GSM physical layer and sends a measurement request for the GSM cells to the GSM physical layer. The GSM physical layer performs measurement on the GSM cells and reports a measurement value to the RR/GRR. The RR/GRR reports the measurement value for GSM cells, received from the GSM physical layer, to the URRC. The URRC reports the received measurement value for GSM cells to the UTRAN.

Forensics and the GSM mobile telephone system

Abstract: The GSM system has become the most popular system for mobile communication in the world. Criminals commonly use GSM phones, and it is therefore a need for forensic investigators to understand which evidence can be obtained from the GSM system. This paper briefly explains the basics of the GSM system. Evidence items that can be obtained from the Mobile Equipment, the SIM and the core network are explored. Tools to extract such evidence from the components of the system exist, but there is a need to develop more sound forensic procedures and tools for extracting such evidence. The paper concludes with a short presentation on the future UMTS system, which largely builds on the design of GSM. All these factors make it important for forensic investigators to understand how the GSM system works, and how evidence can be extracted from it. Criminals took the step into the mobile age a long time ago, and information from the mobile system can give the investigator crucial information on the criminal's actions. It is however important that the information contained in the system is retrieved with a forensically sound method. It is equally important that the investigator understands the system in order to be able to explain to the courts how the system works. It is the aim of this paper to give forensic investigators an introduction to the current state of GSM forensics, and highlight some of the issues that will have to be solved in the future. 2.0 History of the GSM system In the beginning of the 1980s several different systems for mobile communications were developed in Europe. The need for a common system that allowed roaming between countries was early recognized. In 1982 a number of European countries created a new standardization organisation called "Groupe Speciale Mobile" (GSM). The mandate of this group was to develop a standard to be common for the countries that created it. In 1988 the GSM was included in the European Telecommunication Standards Institute (ETSI), and the standards developed by GSM thus became standards for all telecommunication administrations in Europe. The main work with the GSM took place from 1988 - 1990 and resulted in 12 series of specifications which in great detail specified the inner workings of GSM. In 1990, when phase 1 of the specifications was finished, there were three dominating automatic systems for mobile communications in the world:

Distributed wireless network employing utility poles and optical signal distribution

Abstract: Methods and apparatus for providing wireless data or voice coverage in a region by employing existing poles as part of a distribution network. Base station equipment is placed in a co-location facility, and then the BTS signals are distributed over a communication network to remote pole locations, where the signal is radiated from antennas mounted on the poles. This coverage can employ various current and future standards, including cellular standards such as GSM, CDMA, and UMTS, and IP data standards such as 802.11a and 802.11b.

Mobile location estimation based on differences of signal attenuations for GSM systems

Abstract: Radio location by time advance for GSM systems had been published. However, the resolution of time advance in GSM systems is too coarse to locate a mobile's position. The paper proposes a mobile location estimation based on the differences of downlink signal attenuations. This provides a possible mobile location method if the relationship between distance and signal attenuation is determined. Then, the mobile location can be estimated from those possible locations. The error of the proposed method is much smaller than the error of the cell-ID method in the practical microcell system. The greatest advantage of this method is the non-necessity of a known and accurate path loss model and the reduction of the shadowing effect.

Method and apparatus for accessing a network using remote subscriber identity information

Abstract: Method and apparatus for accessing a network using remote subscriber identity information. Subscriber identity information in a memory store within a device such as a mobile terminal can be remotely used by a second independent device. In the case of a GSM terminal, for example, one terminal would be able to utilize the subscriber identity information contained in the subscriber identity module (SIM) of another terminal by establishing a local communication link between the two terminals. Remote subscriber identity information is transferred over the local communication link and the communication terminal, which is using the remote subscriber identity information can register with the network using that information, thus, eliminating the need to transfer the SIM.

Implementation of an augmented reality system on a PDA

Abstract: We present a client/server implementation for running demanding mobile AR application on a PDA device. The system incorporates various data compression methods to make it run as fast as possible on a wide range of communication networks, from GSM to WLAN.

Polar modulator for multi-mode cell phones

Abstract: This paper describes the architecture for a CMOS polar modulator IC that supports AMPS, ANSI-136, GSM/GPRS, and EDGE in a single modulator. Extension to include UMTS has been prototyped. The paper includes design details and evaluation results. The architecture has a high digital content and is potentially suitable for integration into baseband ICs. Performance results for transmitters using this design are included.

Location-Based Services — An Overview of the Standards

Abstract: 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

Single antenna interference cancellation (SAIC) for GSM networks

Abstract: This paper presents field trial results for downlink interference cancellation in a live GSM network. Uplink interference cancellation techniques have been developed in the past, which exploit the use of multiple receive antennas. However, downlink techniques are typically limited to just the use of a single receive antenna due to space limitations, cost considerations and aesthetics associated with current mobile station designs. A prototype mobile station, using a low complexity single antenna interference cancellation (SAIC) algorithm, was constructed, and used to assess the network gain in both asynchronous and synchronous GSM networks. The performance results measured show that SAIC techniques can provide significant gains in C/I. In addition, network simulations indicate that this same algorithm can support voice capacity gains of 39-57%. Thus, SAIC is seen to be a very viable technology for GSM capacity improvement, which can be realized in the next generation of mobile stations.

Method and system for providing authentication of a mobile terminal in a hybrid network for data and voice services

Abstract: The present disclosure provides a method and system for passing information required by a wireless procedure in a hybrid wireless network (300) before the procedure is invoked, the hybrid wireless network (300) having at least one radio access network (304, 306, 307) based on a first technology and a core network (302) based on a second technology. The hybrid network (300) implements a special mobile switching center (308) to be a “double agent” passing information between the mobile terminal (310, 320, 364) and entities in its core network (302). In the context of messaging, the message contents may be encoded, packaged, and decoded appropriately. The present disclosure does not introduce any changes to telecommunication standards such as the GSM and CDMA standards governing the messaging process.

A fully integrated zero-IF transceiver for GSM-GPRS quad band application

Abstract: A GPRS GSM850/GSM/DCS/PCS fully integrated transceiver occupies 14mm/sup 2/ in 0.35/spl mu/m SiGe technology. A direct conversion receiver, transmitter, synthesizer, VCO, voltage regulators and loop filters are fully integrated. The chip meets the GPRS specifications including settling time of 105/spl mu/s in RX mode, NF of 3dB for GSM, TX phase error of 2/spl deg/ RMS, and PLL phase noise of -84dBc/Hz at a 1kHz offset at 3.6GHz.

Scheduling neighbor cell measurements for multiple wireless communication systems

Abstract: Techniques for scheduling measurements for cells in multiple (e.g., GSM and W-CDMA) wireless communication systems are described. GSM neighbor cells are categorized based on a number of states. The states are prioritized in a manner to achieve good performance. The GSM neighbor cells are thus assigned different priorities depending on their states. W-CDMA neighbor cells are prioritized relative to the states for GSM cells. All W-CDMA neighbor cells can be assigned the same state, given the same priority, and considered as “one” W-CDMA cell in the scheduling. A cell in the GSM or W-CDMA system is selected based on the priorities of the neighbor cells, and the selected cell is scheduled for measurement in the next available frame. The highest-ranking GSM or W-CDMA cell for each idle frame is thus granted use of that idle frame for measurement.

Techniques for supporting GSM to W-CDMA reselection

Abstract: Techniques to support cell reselection from GSM to W-CDMA. A dual-mode terminal determines whether or not the GSM network that it is currently camped on supports Release 99 functionality and hence whether or not the GSM network is capable of broadcasting information for W-CDMA neighbor cells. This determination may be made based on the settings for certain status bits in messages transmitted by the GSM network and/or other information available to the terminal. The terminal can initiate a search for W­CDMA cells if it is deemed that the current GSM network does not support Release 99 functionality. The terminal may also determine the scope of the W-CDMA search and when to perform the W-CDMA search based on information stored by the terminal. The reselection from GSM to W-CDMA may be achieved based on measurements obtained from the W-CDMA search and other pertinent information (e.g., threshold values used to compare the measurements).

GPRSWeb: optimizing the web for GPRS links

Abstract: The General Packet Radio Service (GPRS) is being deployed by GSM network operators world-wide, and promises to offer users "always-on" data access at bandwidths comparable to that of conventional fixed-line telephone modems. Unfortunately, many users have found the reality to be rather different, experiencing very disappointing performance when, for example, browsing the web over GPRS.In this paper we investigate what causes the HTTP protocol and its underlying transport TCP to underperform in a GPRS environment. We examine why certain GPRS network characteristics interact badly with TCP to yield problems such as: link under-utilization for short-lived flows, excess queueing for long-lived flows, ACK compression, poor loss recovery, and gross unfairness between competing flows. We also show that many web browsers tend to be overly aggressive, and by opening too many simultaneous TCP connections can aggravate matters.We present the design and implementation of GPRSWeb - a mobile HTTP proxy system that mitigates many of the performance problems with a simple software update to a GPRS mobile device. The update is a 'client proxy' that sits in the mobile device, and communicates with a 'server proxy' located at the other end of the GPRS link close to the wired-wireless border. The dual proxy architecture collectively implements a number of key enhancements - an aggressive caching scheme that employs content-based hash keying to improve hit rates for dynamic content, a preemptive push of web page support resources to mobile clients, resource adaptation to suit client capabilities, delta encoded data transfers, DNS lookup migration, and a UDP-based reliable transport protocol that is specifically optimized for use over GPRS. We show that these enhancements result in significant improvement in overall WWW performance over GPRS.

Life cycle assessment of the mobile communication system UMTS: towards eco-efficient systems

Abstract: Telecommunication providers and telecommunication manufacturers are getting ready to implement the third generation (3G) mobile telecommunication systems known as UMTS (Universal Mobile Telecommunication System) in Europe. Next to the technical problems involved, no statement regarding the sustainability of the UMTS can yet be made. In a joint effort Motorola, Swisscom, Deutsche Telekom and ESU-services have carried out an evaluation of the environmental sustainability of the UMTS mobile communication system in Switzerland by means of a life cycle assessment (LCA). A baseline environmental impact profile across the full life cycle of the UMTS mobile communication system and its predecessor, the GSM (Global System for Mobile Communication) is presented. The baseline assessment was a necessary first step to evaluate the environmental impacts of the mobile communication systems use and growth and thus permitting the evaluation of its environmental sustainability. The analysis showed that the manufacturing of electronic components, the life time of the appliances and energy consumption are key parameters influencing the environmental profile most. From this baseline, necessary environmental improvement strategies on the technical level, such as design for environment for products (e.g. cellular phone and base stations) and LCA improvement assessments (e.g. combined devices) are developed so as to show ways towards sustainable mobile communication.

Controller for gsm and 3g base transceiver stations in a gsm core network with external handover possibility from 3g cells to gsm cells transparent to gsm core network

Abstract: A station controller (M-BSC) is connected to base transceiver stations BTS of the GSM (Global System for Mobile), or DCS (Digital Cellular System) mobile transceiver system, and to BTSC base transceiver stations of the TD-SCDMA (Time Division Synchronous Code Division Multiple Access) system through code division transceiver access technology, typical of 3G systems, and TDD duplexing. The controller is connected to a MSC circuit switch of GSM type. The new 3G technology shares the GSM core network, which on the contrary ignores the existence of the latter. Transparency of the 3G new technology towards the core network is achieved inhibiting any handover from GSM cells to BTSC cells and enabling the external handover (through MSC intervention) from BTSC cells to GSM cells after appropriate treatment of information to be sent to MSC. The ad hoc procedure is carried out by the station controller and consists in reprocessing the mixed list (2G and 3G) of cells candidate for handover furnished with by BTSC, to obtain two lists of cells differing as to radio technology, selecting a list to be forwarded to MSC according to service qualification criteria, comparing in a local memory the (MS/UE) mobile classmarks owned by MSC with those associated to the selected list and, in case of inconsistency, updating MSC classmarks prior to the forwarding of the selected list.

Mobile phone tribes: Youth and social identity

Abstract: A survey carried out in October 2000 by a producer in the Global System for Mobile Communications (GSM)1 leads us straight to a group of GSM users. It tells us about their buying habits, their use of GSMs and short-message services (SMSs), and what they spend. But who are these young people? This is the first question that the sociologist asks. What social circles do they belong to; what is their school background, their daily social and family life? A contextualization of the survey would have been extremely useful for analyzing the data collected because, behind the sometimes staggering figures on phone calls, SMS messages, and above all money spent on GSM, are young people whom we would like to know more about. Behind GSM there hides a problem of social identity.