Showing papers on "GSM published in 1994"

Two user location strategies for personal communications services

Abstract: The vision of nomadic personal communications is the ubiquitous availability of services to facilitate the exchange of information between nomadic end users independent of time, location, on access arrangements. To realize this, it is necessary to locate users who move from place to place. The strategies commonly proposed are two-level hierarchical strategies, which maintain a system of home and visited databases/spl mdash/home location register (HLR) and visitor location register (VLR)/spl mdash/to keep track of user locations. Two standards exist for carrying out two-level hierarchical strategies using HLRs and VLRs. The standard commonly used in North America is the Electronics Industry Association/Telecommunications Industry Association (EIA/TIA) Interim Standard 41 (IS-41), and in Europe the Global System for Mobile Communications (GSM). The authors introduce these two strategies for locating users and provide a tutorial on their usage. Different forms of mobility in the context of PCS and a reference model for a PCS architecture are discussed. The user location strategies specified in the IS-41 and GSM standards are described, and then, using a simple example, a simplified analysis of the database loads generated by each strategy is presented. Also briefly discussed are possible modifications to these protocols that are likely to result in significant benefits by reducing query and update rate to databases and/or reducing the signaling traffic. >

Receiver having for charge-coupled-device based receiver signal processing

Abstract: This invention relates to a novel receiver architecture, the Charge-Coupled-Device Integrated Receiver (IR), which simplifies electronic circuitry requirements and reduce baseband processing rates through efficient signal processing. The focus of this receiver's design is its use of Charge-Coupled-Device (CCD) technology. By using CCD's, in conjunction with other key technologies, to implement the signal processing techniques disclosed herein, it is possible to provide a receiver that is suitable for a wide range of applications (e.g., communications, sonar, radar, etc.). Information is presented which outlines the fundamental receiver architecture that is appropriate for a wide range of commercial services (e.g., AMPS, NAMPS, Digital Cellular, GSM, PCS, ISM, CT1, CT2, etc.) Furthermore, tile versatility of this architecture makes it suited for uses ranging from simple AM/FM receivers to complex high-order modulation TDMA/CDMA receivers.

The capacity of broadband CDMA overlaying a GSM cellular system

Abstract: The author proposes that one can overlay an existing GSM cellular network with a broadband CDMA cellular system utilizing direct-sequence spread spectrum alone with agile notch filters at the base station. Notch filter depths of 35 dB on receive and 20 dB in transmit were found to be adequate. Capacity calculations show that the B-CDMA overlay can approximately quadruple the nominal capacity of GSM, which is 16 channels per sector, by providing an additional 51 voice channels at 16 kbps each. Also, the author has calculated that the B-CDMA mobile transmits on average with 16 dB less power than the GSM mobile, while the CDMA base transmit power per channel would be about 5.5 dB less than the GSM base due to the lower CIR required by the B-CDMA overlay system. >

Cellular telephone with datagram and dispatch operation

Abstract: A cellular system supports dispatch and datagram operations. The architecture of a conventional cellular system, such as the GSM system, is modified by adding a local area network (TIL) where nodes on the network include various base switching controllers (BSC). The BSC has a Switching Interface Module (SIM) which provides an interface to the TIL. The TIL may also include one or more gateways (40) to landline based networks. The datagram operation uses an appropriate gateway to complete a data path which includes an RF segment to or from the BSC. Dispatch operations provide for switching by the BSC so that switching is at a level below the Mobile Switching Center (MSC). For example, compressed voice traffic received by the BSC may be transmitted over the TIL to another BSC from where it is sent over an RF segment to a mobile receiver (MS).

Location management strategies for mobile cellular networks of 3rd generation

Abstract: Several location management strategies applicable in cellular networks are presented. Analytical modelling approaches for signalling cost minimisation are discussed. Results of a GSM based case study are given that are applicable to cellular radio systems of the 3rd generation like MBS and UMTS. A hybrid dynamic strategy is proposed for a public MBS. >

Enhanced decoder for a radio telephone

Abstract: The invention provides an improved method and apparatus for identifying a bad GSM speech frame. Both the estimated signal-to-noise ratio (ESNR) of the received signal and the pseudo bit error rate (PBER) of a recorded speech signal are used to determine whether or not a speech frame is bad.

New methods for processing GSM radio measurement data: applications for locating, handover, and network management

Abstract: The GSM system provides measurement data about the radio propagation situation that is used for power control and handover decisions. Currently implemented algorithms use averages of the measurement data and comparison with thresholds for these decisions. As the variations of the measured receive levels are characteristic for the route the mobile station is travelling on, pattern recognition is proposed to determine the position of the mobile station and for handover control. Two approaches are presented-one based on neuro-fuzzy methods and the other based on hidden Markov models-and it is shown that patterns are sufficiently characteristic for the proposed application. >

Measured performance of data transmission over cellular telephone networks

Abstract: Recent developments in mobile communication and personal computer technology have laid a new foundation for mobile computing. Performance of the data communication system as seen by an application program is a fundamental factor when communication infrastructure at the application layer is designed. This paper provides results of performance measurements of data transmission over two different cellular telephone networks, a digital GSM-network and an analogue NMT-network. Since our emphasis is on performance as seen by application programs, we use the standard TCP/IP protocols in the measurements. The performance is measured using three basic operations: establishment of a wireless dial-up connection, exchange of request-reply messages, and bulk data transfer. The external conditions under which the measurements were carried out present a normal office environment when the field strength of the cellular link is good or fairly good.

Supporting Adaptive Services in a Heterogeneous Mobile Environment

Abstract: Future computer environments will include mobile computers which will either be disconnected, weakly interconnected by low-speed wireless networks such as GSM (global system for mobile communications), or fully interconnected by high-speed networks ranging from Ethernet to ATM (asynchronous transfer mode). While the transition between networks is currently a heavyweight operation, we believe that developments in network interface technology will soon enable mobile computers to dynamically select their network service based on cost and performance requirements. Such flexibility, coupled with the inherent unreliability of mobile communications, means that system services and applications will be subject to rapid and massive fluctuations in the quality-of-service provided by their underlying communications infrastructure. In this paper, we discuss the design of a distributed systems platform to support the development of services which are able to tolerate this environment by dynamically adapting to changes in the available communications quality-of-service.

Concept of a GSM-based communication system for high-speed trains

Abstract: The paper outlines the concept of a GSM-based communication system for high-speed trains up to 500 km/h. Special services for the railroad operator as specified by the UIC Radio Group are provided. Passenger communication using standard GSM terminals is supported. A possible architecture for the communication system is presented and discussed. Similarities and modifications necessary to existing GSM equipment are highlighted. >

A method and arrangement relating to telecommunications systems

Abstract: The present invention relates to a roaming arrangement (100). The arrangement enables roaming between different types of networks in a telecommunication system (TS, TSX). The telecommunication system (TS) comprises a first standardized type of mobile network in the telecommunication system (TS), a so-called home network (PDC). The telecommunication system (TS) also comprises a second standardized type of mobile network, a so-called guest network (GSM). A subscriber (A) have an identity that is common for both the home net (PDC) and the guest net (GSM). The roaming arrangement (100) comprises a signal handling arrangement (ILR, IMSC). The roaming arrangement (100) also comprises at least one home interface (S1, S2) towards the home net (PDC) and at least one guest interface (S2, S4) towards the guest net (GSM). A first signalling format between the arrangement (100) and the home net (PDC) is thereby of the same type as a corresponding format in the home net (PDC). A second signalling format between the arrangement (100) and the guest net (GSM) is thereby also of the same type as a correspnding format in the guest net (GSM).

FH-GSM frequency hopping GSM

Abstract: The GSM system of today is evolving towards smaller cells and higher traffic capacity. The need for microcell and even picocell systems will be greatly increased in the near future. One of the most important factors will then be to provide high traffic capacity and to provide an easy way of performing frequency planning for the system operator. In this paper we present results from system simulations based on the GSM recommendation phase two. We show that the use of power regulation in both up- and downlink in combination with discontinuous transmission (DTX) and slow frequency hopping makes it possible to decrease the frequency reuse distance below 3/9 whilst maintaining system performance. Results from simulations with different frequency reuse distances are presented. System characteristics such as capacity, quality and robustness are evaluated and compared to a fixed plan reference system without frequency hopping or DTX. >

Fixed cellular communications system

Abstract: A fixed cellular communications system consisting of a cellular mobile communications network (CS) that provides coverage of voice and/or data communications services to terminals located in a set of cells in any one of which there can be at least one fixed cellular terminal (4) that communicates, on one side, by radio, with one of the base stations (3) of the cellular mobile communications network (CS) and on the other side, by cable, with at least one base station (6) of a cordless communications system (WS) through control and interface means that perform the adaptation between the two systems to provide communications services to a number of cordless terminals (7). When the cellular communication system (CS) makes use of a time division multiple access technology, for example GSM, one single radio transceiver is connected to a transceiver control means to manage the radio channel allocations, so that it can simultaneously support as many communications channels as possible without there being temporal overlapping of channels.

Continuous location of moving GSM mobile stations by pattern recognition techniques

Abstract: Pattern recognition techniques based on hidden Markov models, which are applied to GSM measurement data, have been shown to be appropriate for the determination of the mobile station's location. For computational reasons this is so far limited to a certain number of locations in the road network. Here it is discussed how the number of locations can be increased and how the mobile station can be continuously kept track of once its position has been determined. Splitting the model in smaller parts has been found to be the solution to this problem and it is explained here how this can be treated mathematically.

Overview of GSM: Philosophy and results

Abstract: The work on GSM, a standardized European second-generation cellular system, was started in 1982 in order to prevent the fragmentation of the first-generation cellular market from continuing into the second generation. The goal was to define a system with open interfaces for Pan-European use that would offer the best compromise between a number of conflicting requirements, such as spectrum economy, high speech quality, low cost, and a large range of services. A broad outline of the novel features is presented, both concerning the architecture of the system and of the services offered, as well as the reasoning behind the more important choices. Finally, some views are presented concerning the future development of GSM and of the third-generation system, the co-called Future Public Land Mobile Telecommunication System, commonly referred to as FPLMTS.

Mobile telephones interfere with medical electrical equipment.

Abstract: Electromagnetic interference in medical electrical equipment has not been a serious problem in recent years even with the proliferation of analogue mobile phones and two-way handheld radios. With the introduction of GSM digital mobile phones into Australia we have conducted measurements and found that, within 2m, the electric fields from digital mobile phones can exceed the immunity level of 7 V/m recommended by the US Food and Drug Administration (FDA) for medical electrical equipment. Current analogue mobile phones were shown to produce electric fields that exceed the 7 V/m level only at relatively shorter distances. In another test, both analogue and digital mobile phones were operated close to a range of typical medical electrical equipment. It was found that existing equipment generally meets the FDA standard, but digital mobile phones caused a variety of artefacts and alarm conditions. This problem must be addressed by the medical engineering profession; in the meantime, nursing and other staff should be educated to recognise these problems and restrictions must be placed upon the use of mobile phones in hospitals.

Application of space division multiple access to mobile radio

Abstract: An approach is proposed to introduce a space division multiple access (SDMA) component into a frequency/time division multiple access (FTDMA) mobile radio system like the European GSM system providing higher frequency reuse and spectral efficiency. Except from signalling aspects the mobiles remain uneffected by the presented SDMA method without any need for antenna diversity or more sophisticated equalizers. Additional hard- and software-demands due to the new SDMA features are only restricted to base stations as they have to be equipped with an adaptive antenna array. This array is used to separate wavefronts in coherent multipath environments by means of a new algorithm. The number of antenna elements needed is significantly lower than the number of wavefronts impinging on the array.

Simplified Viterbi processors for the GSM Pan-European cellular communication system

Abstract: The GSM cellular system provides the European countries with a common digital mobile radio structure for overland communications. This paper illustrates an implementation of a GSM receiver in which two reduced complexity Viterbi processors are used: the first one for the demodulation of the GMSK signal and the second one for the decoding operations. The performance of the receiver is evaluated through a channel simulator for mobile communications. The results show that in many cases the proposed receiver allows the significant reduction of the computation complexity with respect to the classical Viterbi processor. In particular, for mean and high signal-to-noise ratios, a reduction of four times in the computational burden is obtained. >

Method and arrangement for measuring the condition of a base station

Abstract: The invention relates to a method for measuring the condition of a receiving antenna of a base station in a TDMA radio system, in which TDMA channel structures according to ETSI/GSM recommendation 05.02 are used, by means of test measurements performed in predetermined TDMA time slots. According to the invention, the test measurements are performed, without disturbing the normal operation of the base station and without allocating a traffic channel, during time slots of an IDLE frame of a channel structure TCH/F+SACCH/TF and/or during time slots of an IDLE frame of a channel structure SDCCH/8 according to the ETSI/GSM recommendation 05.02.

Comparison of upgrade techniques for mobile communication systems

Abstract: For current mobile communication systems, two limitations exist which restrict their capacity and range of application. They can be characterised as an equipment limit which is determined by the maximum number of mobile stations that can be supported by a base station with given equipment, and an interference limit, which corresponds to a maximum number of carriers that can be used in a cell if a given signal-to-interference ratio must be guaranteed. Depending on base station (BS) equipment dimensioning and propagation conditions in the cell coverage area, one of the two limits will apply and define a maximum capacity of the base station that cannot be exceeded without modifications of the base station. Several techniques for base station upgrades have been developed which focus on one of the two limits or both. In the paper, traditional techniques such as spectrum upgrade, sectorisation, codec rate reduction and cell splitting are revised and compared to a new technique called A-SDMA (adaptive space division multiple access), which is introduced. Based on the comparison, evolution plans for different areas of application are developed which take these upgrade techniques into account and provide upgrade paths for mobile communication system infrastructures, applicable to current systems such as GSM as well as future systems (UMTS, FPLMTS). >

Resource auction multiple access (RAMA) in the cellular environment

Abstract: Resource auction multiple access (RAMA) is a technique for rapidly assigning communication resources (e.g., frequency carriers and/or TDMA time slots) in a wireless environment. This scheme is deterministic in that, barring errors caused by fading and noise, a resource assignment is made in each and every assignment cycle. Previous papers reported on the ultimate call assignment capacity of this technique, limited only by propagation delays, and also demonstrated its capabilities for statistical speech multiplexing in a PCS environment. We extend the previous work in two directions: (1) we examine the effects of channel fading and noise; and (2) we consider both GSM and IS-54 cellular environments. Propagation is modeled, for purposes of this study, as flat Rayleigh fading, with mean propagation loss as a parameter. We focus on the subscriber-to-base link and consider several forms of diversity at the base. We also consider two RAMA modes (call assignment without and with statistical speech multiplexing). We show that a simple form of two-branch diversity can be very effective. In both GSM and IS-54, for example, using simple diversity and an average transmit power of 100 mw yields assignment error probabilities of only 1% for losses as high as 151 dB. >

Short message service based applications in the GSM network

Abstract: Mobile data services represents a new frontier in the benefits that can be offered to the mobile customer, which have hitherto included voice only in addition to the characteristic terminal mobility. In view of the limitations and costs of mobile communication, the most interesting data services appear to be the "virtual circuit" services, i.e. those in which the mobile radio network assigns radio resources dynamically and only during the actual transmission. A further aspect to be borne in mind is the user coverage conditions, as inadequate coverage would limit connectivity prerogatives and preclude the use of the service by customers such as vehicle fleet operators for whom mobility is a basic, if not indeed overriding consideration. An answer to this kind of demand is provided by the pan-European GSM network with the voice integrated short message service, or SMS. The article introduces the SMS architecture and shows, using the SMS facilities, how to provide services, which includes transmission of location information, credit cards authentication, computer-based messaging and remote monitoring to mobile customers within GSM coverage area.

Highly-integrated transmitter RFIC with monolithic narrowband tuning for digital cellular handsets

Abstract: Digital cellular systems are currently replacing older analog systems globally as consumers demand higher quality transmission, lower cost, and better access. Handset manufacturers are reducing the size, weight, cost and power consumption of portable terminals to address larger consumer market segments. The Si bipolar radio-frequency integrated circuit (RFIC) in this work addresses the transmit sections of handsets for the North American Digital Cellular (NADC) system at 824-849 MHz, the Groupe Specialle Mobile (GSM) European system at 890-915 MHz and the Japan Digital Cellular (JDC) system at 940-956 MHz. >

On Fibonacci keystream generators

Abstract: A number of keystream generators have been proposed which are based on Fibonacci sequences, and at least one has been fielded. They are attractive in that they can use some of the security results from the theory of shift register based keystream generators, while running much more quickly in software. However, new designs bring new risks, and we show how a system proposed at last year's workshop, the Fibonacci Shrinking Genertor (FISH), can be broken by an opponent who knows a few thousand words of keystream. We then discuss how such attacks can be avoided, and present a new algorithm, PIKE, which is based on the A5 algorithm used in GSM telephones.

A coherent detection scheme for the uplink channel in a CDMA system

Abstract: In a joint European research effort, code division multiple access is studied as a possible candidate for future mobile systems. In the paper a coherent detection scheme is described which uses only a modest overhead. >

The Challenges for analog circuit design in Mobile radio VLSI chips

Abstract: Mobile radio telephony is becoming a driving application for analog circuit design and silicon CMOS and RF bipolar technology. New telecom systems like GSM, PCN, DECT, Wireless in the loop ... are all developing very rapidly and will enable us very soon to organise a complete telephone network with full coverage for your mobile car phone, as well as in your kitchen and on your office desk. In Europe the major telecom companies have worked together to establish one common standard for cellular mobile radio communications at 900MHz. Similar things are happening for other wireless personal communication systems. Basically the cellular radio telephone, the wireless PABX and the wireless SLIC are bringing the same challenges to analog circuit design: maximum integration of the basic radio functions into 1 or 2 silicon chips, CMOS, Bipolar or BICMOS or GaAs.

CDMA or TDMA? CDMA for GSM?

Abstract: The multiple access schemes TDMA and CDMA are compared and evaluated with respect to the demands on third generation mobile radio systems such as high capacity and flexibility. Further, an approach to evolve GSM towards third generation mobile radio systems by introducing an optional CDMA component is presented.

Future CDMA cellular mobile systems supporting multi-service operation

Abstract: The two major requirements of future cellular mobile and personal communication systems are: the support of multi-rate services and operation in multi-cell environments. This paper is concerned with the identification and development of efficient and flexible methods of mapping logical traffic and control channels onto physical channels at the air interface for future multi-rate CDMA systems. We also address how a GSM 900/DCS 1800 fixed network may be evolved to support such systems.

Digital mobile radio network station with speech signal exchange means and data signal exchange means

Abstract: A mobile station of a mobile radio network includes speech exchange arrangements and data exchange arrangements. Selector arrangements select the speech exchange arrangements by default and change to the data exchange arrangements when necessary. The data exchange arrangements comprise a set of components for sorting, analyzing and processing the data and the commands exchanged between two terminal equipments so that a mobile terminal equipment capable of exchanging data according to a first standard (the V.24 standard+modem protocol, for example) can communicate with another, remote terminal equipment via a digital network using a second standard (V.110+GSM network, for example).