Showing papers on "Cellular network published in 1998"

Overview of radiolocation in CDMA cellular systems

Abstract: Applications for the location of subscribers of wireless services continue to expand. Consequently, location techniques for wireless technologies are being investigated. With code-division multiple access (CDMA) being deployed by a variety of cellular and PCS providers, developing an approach for location in CDMA networks is imperative. This article discusses the applications of location technology, the methods available for its implementation in CDMA networks, and the problems that are encountered when using CDMA networks for positioning.

Spreading codes for direct sequence CDMA and wideband CDMA cellular networks

Abstract: This article presents an overview of the spreading techniques for use in direct sequence CDMA cellular networks. We review the theoretical background for sequences used in CDMA and wideband CDMA, and discuss the main characteristics of the maximal length, Gold (1967, 1968), and Kasami sequences, as well as variable- and fixed-length orthogonal codes. We also describe different methods of multiple spreading for channelization and scrambling in CDMA and W-CDMA realizations.

BLUETOOTH—The universal radio interface for ad hoc, wireless connectivity

Abstract: that is small enough to fit inside any electronic device or machine, that provides local connectivity, and that creates a (worldwide) micro-scale web. What applications might you use it in? In 1994, Ericsson Mobile Communications AB in Lund, Sweden, initiated a study to investigate the feasibility of a low-power, low-cost radio interface between mobile phones and their accessories. The intention was to eliminate cables between phones and PC cards, wireless headsets, and so forth. The study was part of a larger project that investigated multi-communicators connected to the cellular network via cellular telephones. The last link in the connection between a communicator and the cellular network was a short-range radio link to the phone—thus, the link was called the multicommunicator link or MC link. As the MC link project progressed, it became clear that there was no limit to the kinds of application that could use a short-range radio link. Cheap, short-range radios would make wireless communication between portable devices economically feasible. Current portable devices use infrared links (IrDA) to communicate with each other. Although infrared transceivers are inexpensive, they • have limited range (typically one to two meters); • are sensitive to direction and require direct line-of-sight; • can in principle only be used between two devices. By contrast, radios have much greater range, can propagate around objects and through various materials, and connect to many devices simultaneously. What is more, radio interfaces do not require user interaction. In the beginning of 1997, when designers had already begun work on an MC link

Positioning GSM telephones

Abstract: Due to the FCC requirement that operators of mobile communications networks be able to accurately locate mobile callers requesting emergency assistance via 911 by the year 2001, there has been a lot of activity among cellular and PCS providers to examine cellular positioning options. This article examines positioning solutions for the GSM group of standards. Worldwide deployment of GSM systems is well underway, and the positioning characteristics of the various systems are similar. The authors examine the ability to derive position information from GSM signals, based on their May 1996 achievement of accurate position measurements using GSM. Features of GSM signals relevant to positioning are analyzed as well as results achieved and the authors' ongoing positioning trials. Finally, other issues related to GSM positioning and mobile phone positioning in general are covered.

Subscriber location in CDMA cellular networks

Abstract: Subscriber radio location techniques are investigated for code-division multiple-access (CDMA) cellular networks. Two methods are considered for radio location: measured times of arrival (ToA) and angles of arrival (AoA). The ToA measurements are obtained from the code tracking loop in the CDMA receiver, and the AoA measurements at a base station (BS) are assumed to be made with an antenna array. The performance of the two methods is evaluated for both ranging and two-dimensional (2-D) location, while varying the propagation conditions and the number of BS's used for the location estimate.

An overview of air interface multiple access for IMT-2000/UMTS

Abstract: The basis for any air interface design is how the common transmission medium is shared between users (i.e., multiple access scheme). The underlying multiple access method for all mobile radio systems is FDMA. The performance of TDMA and CDMA has been subject to vigorous debate, without any definitive conclusions. This article gives an overview of worldwide research and standardization activities related to the multiple access schemes for third-generation mobile communications systems IMT-2000 and UMTS.

Common access between a mobile communications network and an external network with selectable packet-switched and circuit-switched and circuit-switched services

Abstract: Applications running on a mobile station or an external network entity such as an Internet service provider may specify on an individual application flow basis a requested quality of service. From that requested quality of service, an optimal type of bearer to transfer the application flow through the mobile communications network is determined. For example, a circuit-switched bearer may be allocated if the request is for a real-time service, and a packet-switched bearer may be allocated if the request is for a non-real time type of service. Various other decision making criteria may be employed. A mobile station and a mobile network gateway node each include a mapper for mapping an individual application flow to one of a circuit-switched network and a packet-switched network bearer depending on the quality of service requested for the individual application flow. The network layer quality of service parameters corresponding to an individual application flow are mapped to circuit-switched bearer parameters if the application flow is mapped to the circuit-switched network and to packet-switched bearer parameters if the application flow is mapped to the packet-switched network. The gateway node includes a common access server which permits a mobile station initially establishing a communications session with an external network entity to perform only a single, common access procedure for subsequent communications using one of the circuit-switched and packet-switched networks. After that common access procedure is completed, subsequent application flows between the mobile station and the external network entity are established using abbreviated procedures without having to access the external network entity.

System and method for authorization of location services

Abstract: A telecommunications system and method is disclosed which performs authorization checks prior to allowing a location service to position a mobile terminal within a cellular network. The various checks involve ensuring that the requesting agency has authorization to request positioning of mobile terminals, determining whether positioning of mobile terminals is allowed within the cellular network that the mobile terminal is currently located in, verifying the authenticity of the identity of the mobile positioning center, ascertaining whether the mobile subscriber has allowed the requesting agency to position the mobile terminal, and confirming that all relevant criteria for positioning have been met by both the mobile subscriber and the requesting agency.

Predictive and adaptive bandwidth reservation for hand-offs in QoS-sensitive cellular networks

Abstract: How to control hand-off drops is a very important Quality-of-Service (QoS) issue in cellular networks. In order to keep the hand-off dropping probability below a pre-specified target value (thus providing a probabilistic QoS guarantee), we design and evaluate predictive and adaptive schemes for the bandwidth reservation for the existing connections' handoffs and the admission control of new connections.We first develop a method to estimate user mobility based on an aggregate history of hand-offs observed in each cell. This method is then used to predict (probabilistically) mobiles' directions and hand-off times in a cell. For each cell, the bandwidth to be reserved for hand-offs is calculated by estimating the total sum of fractional bandwidths of the expected hand-offs within a mobility-estimation time window. We also develop an algorithm that controls this window for efficient use of bandwidth and effective response to (1) time-varying traffic/mobility and (2) inaccuracy of mobility estimation. Three different admission-control schemes for new connection requests using this bandwidth reservation are proposed. Finally, we evaluate the performance of the proposed schemes to show that they meet our design goal and outperform the static reservation scheme under various scenarios.

Communicating packet data with a mobile station roaming within an incompatible mobile network

Abstract: A roaming mechanism enabling a mobile station (20) to roam between a first data packet network (300) utilizing a Mobile IP Method (MIM) and a second data packet network (10) utilizing a Personal Digital Cellular Mobility Method (PMM) is disclosed. A foreign agent (FA) (310) is introduced into the PMM network (10) for enabling a mobile station (20) associated with the MIM network (300) and currently roaming within the PMM network (10) to communicate packet data with an associated home agent (HA) (320). A home agent (HA) is further introduced into the PMM network (10) for enabling a mobile station (20) associated with the PMM network (10) and currently roaming within the MIM network (300) to communicate packet data with an associated FA or Mobile IP Client Emulator (MICE) (1000) currently serving the roaming mobile station (20).

System and method for location-based marketing to mobile stations within a cellular network

Abstract: A telecommunications system and method is disclosed for collecting mobility information regarding mobile subscribers and providing this mobility information to telemarketing companies to generate extra revenue for cellular network operators. A telemarketing application can define a target area, which includes a cell or a number of cells that are of interest for the telemarketing application, and include this defined target area in a mobility request to an Operation and Support System (OSS) within the cellular network. The OSS instructs Mobile Switching Centers (MSCs) within the target area to log the movement of each MS located in the target area and store this mobility information in a Home Location Register (HLR) or Visitor Location Register (VLR). Once all the mobility information has been collected by the MSC's, the mobility information is passed onto the OSS, which can utilize filter parameters specified by the telemarketing application in order to generate tailored mobility information.

Demand-based radio network planning of cellular mobile communication systems

Abstract: This paper presents a demand-based engineering method for designing radio networks of cellular mobile communication systems. The proposed procedure is based on a forward-engineering method, the integrated approach to cellular network planning and is facilitated by the application of a new discrete population model for the traffic description, the demand node concept. The use of the concept enables the formulation of the transmitter locating task as a maximal coverage location problem (MCLP), which is well known in economics for modeling and solving facility location problems. For the network optimization task, we introduced the set cover base station positioning algorithm (SCBPA), which is based on a greedy heuristic for solving the MCLP problem. Furthermore, we present the planning tool prototype ICEPT (Integrated Cellular network Planning Tool), which is based on these ideas and show a first result from a real world planning case.

Radio transmitter location finding in CDMA wireless communication systems

Abstract: A method and apparatus for location finding in a CDMA wireless communication system uses multipath signals in order to accurately determine a transmitter—s location. Direct path and multipath signals from a mobile transmitter arrive at an array of p antennas belonging to a cellular network base station. A location finding apparatus connected to the base station contains a multichannel receiver that uses PN sequence information provided by the base station receiver to despread the p signals and to separate each of the p signals into temporally distinct multipath parts. A signal processor calculates a signal signature for each active mobile. The signature is comprises a code correlation function, a set of temporal delays corresponding to the multipath parts and a set of signal subspaces. The signature is then compared to a database of calibrated signal signatures and corresponding locations, and a location whose calibrated signature best matches the measured signature is selected as the most likely location of the mobile transmitter. The location information can be used to increase the performance of a cellular telephone network and/or to provide useful services to cellular telephone customers.

Soft handover system for a multiple sub-carrier communication system and method thereof

Abstract: A soft handover system is provided for a multiple sub-carrier communication system, applicable to the uplink (mobile unit to base stations) and/or the downlink (base stations to mobile unit). The soft handover system uses multiple sub-carriers to simultaneously transmit multiple sub-carrier signals between at least two base stations and the mobile unit in the uplink and/or downlink. In certain embodiments, the soft handover system provides for synchronized multiple sub-carrier transmission such that the delay differences between the multiple sub-carrier transmissions from the different base stations arriving at the mobile unit are within the guard time of the multiple sub-carrier symbols. Certain embodiments of the soft handover system use the same set of sub-carriers for links between the mobile unit and the base stations of different cells, and other embodiments use different sets of sub-carriers for links between the mobile unit and the base stations of different cells. In the soft handover system using the same set of sub-carriers, the mobile unit receives downlink signals with identical data content from the different base stations. The mobile unit need not distinguish between the signals from the different base stations. The mobile unit just treats the downlink signals from the different base stations as multipath components, thereby increasing the diversity gain. In the case of a multiple sub-carrier CDMA system, the soft handover system can use the same sub-carriers as well as the same CDMA encoding and/or spreading code.

The mobiware toolkit: programmable support for adaptive mobile networking

Abstract: Existing mobile systems (e.g., mobile IP, mobile ATM, and third-generation cellular systems) lack the intrinsic architectural flexibility to deal with the complexity of supporting adaptive mobile applications in wireless and mobile environments. We believe that there is a need to develop alternative network architectures from the existing ones to deal with the tremendous demands placed on underlying mobile signaling, adaptation management, and wireless transport systems in support of new mobile services (e.g., interactive multimedia and Web access). We present the design, implementation, and evaluation of mobiware, a mobile middleware toolkit that enables adaptive mobile services to dynamically exploit the intrinsic scalable properties of mobile multimedia applications in response to time-varying mobile network conditions. The mobiware toolkit is software-intensive and is built on CORBA and Java distributed object technology. Based on an open programmable paradigm developed by the COMET Group, mobiware runs on mobile devices, wireless access points, and mobile-capable switch/routers providing a set of open programmable interfaces and algorithms for adaptive mobile networking.

Common access between a mobile communications network and an external network with selectable packet-switched and circuit-switched services

Abstract: Applications running on a mobile station or an external network entity such as an Internet service provider may specify on an individual application flow basis a requested quality of service. From that requested quality of service, an optimal type of bearer to transfer the application flow through the mobile communications network is determined. For example, a circuit-switched bearer may be allocated if the request is for a real-time service, and a packet-switched bearer may be allocated if the request is for a non-real time type of service. Various other decision making criteria may be employed. A mobile station and a mobile network gateway node each include a mapper for mapping an individual application flow to one of a circuit-switched network and a packet-switched network bearer depending on the quality of service requested for the individual application flow. The network layer quality of service parameters corresponding to an individual application flow are mapped to circuit-switched bearer parameters if the application flow is mapped to the circuit-switched network and to packet-switched bearer parameters if the application flow is mapped to the packet-switched network. The gateway node includes a common access server which permits a mobile station initially establishing a communications session with an external network entity to perform only a single, common access procedure for subsequent communications using one of the circuit-switched and packet-switched networks. After that common access procedure is completed, subsequent application flows between the mobile station and the external network entity are established using abbreviated procedures without having to access the external network entity.

An overview of the IRIDIUM (R) low Earth orbit (LEO) satellite system

Abstract: This paper provides a tutorial overview of the IRIDIUM(R) low earth orbit (LEO) satellite system. Section I contains an introduction to the IRIDIUM(R) network as well as the system specifications. Section II discusses the satellite constellation design, orbital parameters, and horizontal pointing angles between satellites. Section III introduces the idea of time dependent connectivity in a mobile network, and analyzes the cycle of network connectivity for IRIDIUM(R). Section IV discusses the IRIDIUM(R) Time Division Multiple Access (TDMA) and Frequency Division Multiple Access (FDMA) schemes and uses these to calculate the overall system capacity. Section V examines the call processing procedure to include user location and call set up. Finally, Section VI analyzes the network performance in terms of end-to-end delay and hop count.

Interworking between telecommunications networks

Abstract: A mobile telephone (UT 1 ) is configured for dual mode operation, so as to communicate either via an earth-orbiting satellite 3 a with a satellite network (SAN 1 ) or through a conventional land-based cellular network (PLMN 9 ). In order to provide interworking between the satellite network and the land, cellular network 9 , an interworking function (IWF 31 ) provides data to the cellular network 9 concerning the location of the user terminal (UT 1 ) in relation to the satellite network. The data is transmitted from the satellite visitor location register (VLR SAT 1 ) to the home location register (HLR) of the cellular network 9 . The IWF maintains a list of roaming subscribers provisioned with services which are specific to the visited network and not available in the home network. The (IWF 31 ) is configured to operate with local GSM, DAMPS, PHS or other local land-based networks, depending on the geographic location of the SAN.

Apparatus and method for management of resources in cellular networks

Abstract: Wireless networks require efficient mobility management to cope with frequent mobile handoff and rerouting of connections. The invention treats this problem by developing a hierarchical prediction engine that employs approximate pattern matching and Kalman filtering techniques to yield an accurate prediction of both the immediate next cell to be entered by the mobile and the overall or global route of the mobile unit in the wireless cellular network. The prediction of the mobile's future movement is used by the network to reserve resources, relieve congestion, reduce latency, and optimize the establishment of routes in the wireless cellular network.

Enhanced cellular communication system

Abstract: A cellular network comprises a plurality of mobile stations and a plurality of base stations. The base stations are located so that each base station has a zone of effective coverage which does not overlap with the zones of effective coverage of adjacent base stations leaving zones of reduced coverage between the base stations. When a sender station which is outside the zone of effective coverage of a particular base station wishes to send a message to that base station, the message is relayed by another mobile station to the destination base station. The relaying station may be located within the zone of effective coverage, or in the zone of reduced coverage of the destination base station. The sender station, the destination station and the relaying station(s) can all be mobile stations located in zones of reduced coverage. In the zones of reduced coverage, resources such as transmission power, transmission time-slots and frequency channels are utilized on a reduced basis, effectively sharing the resources between the stations.

Transparent non-disruptable atm network

Abstract: A method and apparatus for the transparent, non-disruptable transfer of data, particularly multimedia data, through any packet-based network, such as an ATM network is provided. The method of the present invention includes the step of setting a primary path and a secondary path between nodes of a network, or of a network domain. Accordingly, when a switch or node establishes a Virtual Path (VP) to another switch with specified effective bandwith, it also has an alternate VP that is available, although no bandwidth is actually used. The method of the present invention further includes the step of optimizing the available capacity of the system through management actions. For handling congestion and resource failures, the total effective bandwidth on each physical link is categorized in terms of idle capacity (unused or available), used capacity (for existing VPs), and spare capacity. When a resource failure occurs, the idle capacity is used for real-time switching of the VP and service is not disrupted. This is accomplished by an alarm indication management cell which is delivered when a resource problem is encountered. This management cell sets forth the secondary path and the bandwidth associated therewith. On the other hand, if idle capacity does not exist, the spare capacity is used, while the bandwidth for all other VPs is reconfigured using virtual bandwidth optimization. Therefore, service disruption does not occur. In a wireless, mobile network, the present invention monitors node movement and takes management actions on the basis of such node movement to prevent service disruption.

Spatial traffic estimation and characterization for mobile communication network design

Abstract: This paper presents a new method for the estimation and characterization of the expected teletraffic in mobile communication networks. The method considers the teletraffic from the network viewpoint. The traffic estimation is based on the geographic traffic model, which obeys the geographical and demographical factors for the demand for mobile communication services. For the spatial teletraffic characterization, a novel representation technique is introduced which uses the notion of discrete demand nodes. We show how the information in geographical information systems can be used to estimate the teletraffic demand in an early phase of the network design process. Additionally, we outline how the discrete demand node representation facilitates the application of demand-based automatic mobile network design algorithms.

Selectable packet-switched and circuit-switched services in a mobile communications network

Abstract: Applications running on a mobile station or an external network entity such as an Internet service provider may specify on an individual application flow basis a requested quality of service. From that requested quality of service, an optimal type of bearer to transfer the application flow through the mobile communications network is determined. For example, a circuit-switched bearer may be allocated if the request is for a real-time service, and a packet-switched bearer may be allocated if the request is for a non-real time type of service. Various other decision making criteria may be employed. A mobile station and a mobile network gateway node each include a mapper for mapping an individual application flow to one of a circuit-switched network and a packet-switched network bearers depending on the quality of service requested for the individual application flow. The network layer quality of service parameters corresponding to an individual application flow are mapped to circuit-switched bearer parameters if the application flow is mapped to the circuit-switched network and to packet-switched bearer parameters if the application flow is mapped to the packet-switched network. The gateway node includes a common access server which permits a mobile station initially establishing a communications session with an external network entity to perform only a single, common access procedure for subsequent communications using one of the circuit-switched and packet-switched networks. After that common access procedure is completed, subsequent application flows between the mobile station and the external network entity are established using abbreviated procedures without having to access the external network entity.

System for hybrid wired and wireless geographic-based communications service

Abstract: A geographic-based communications service system has a mobile unit for transmitting/receiving information, and access points connected to a network. The access points are arranged in a known geographic locations and transmit and receive information from the mobile unit. When one of the access points detects the presence of the mobile unit, it sends a signal to the network indicating the location of the mobile unit and the information requested by the mobile unit. Based on the signal received from the access point, the network communicates with information providers connected to the network and provides data to the mobile unit through the access point corresponding to the location of the mobile unit.

Research activities on UMTS radio interface, network architectures, and planning

Abstract: Currently worldwide activities are going on to define third-generation mobile radio systems (IMT-2000 on ITU/UMTS in Europe). These systems aim to support a wide range of services from voice and low-rate data up to high-rate data services, including multimedia services, and circuit- and packet-oriented services. These systems will operate in all radio environments to provide service to anyone, anytime, anywhere. In Europe the European Commission is partly funding research activities in the ACTS framework related to third-generation systems. A spectrum-efficient multiple access scheme proposal is being developed by the ACTS FRAMES project to fulfill the requirements for terrestrial third-generation mobile radio systems. The results and proposals of FRAMES are used as input mainly to the ETSI standardization process. This radio access scheme addresses the different worldwide standardization activities where TDMA and CDMA-based solutions are currently expected. Different proposals for the UMTS system architecture and network issues are currently being discussed in the relevant standardization bodies. On one hand, the GRAN approach envisages a single UMTS access part able to connect with multiple core networks; on the other hand, the generic core network approach proposes to develop UMTS core network functionality able to handle multiple access networks, which can adopt different types of radio access techniques. The ACTS RAINBOW project presents a proposal where both approaches are unified in a system structure. From the network planning viewpoint, the major features of a third-generation mobile system are the wide variety of services provided, the high number of customers expected (especially in urban and densely populated areas), the network architecture flexibility to allow different configurations to be deployed, and the advanced mobility management strategies. From this perspective the ACTS STORMS project is elaborating new planning methodologies tailored to the specific needs of a UMTS operator, and designing and developing a set of software modules covering the whole set of disciplines involved in mobile network planning.

Method and apparatus for simultaneous text and audio for sponsored calls

Abstract: A combination of Global System for Mobile communications (GSM) capabilities including Short Message Service (SMS), Subscriber Identity Module (SIM) and Customized Applications for Mobile network Enhanced Logic (CAMEL) allows an advertiser to pay a portion of the airtime cost of a call originated by a mobile subscriber after that subscriber has listened to a recorded advertisement. The combination delivers a text message that associates with a recorded audio advertisement. The text message, which may be referred to later, is stored by the subscriber's handset and may be a transcript of the audio advertisement, provide additional details of the audio advertisement or it may contain an electronic coupon associated with the advertisement.

Radio coverage optimization with genetic algorithms

Abstract: Cellular network operators are dealing with complex problems when planning the network operation. In order to automate the planning process, the development of simulation and optimization tools are under research. In this paper genetic algorithms with three different approaches are studied in order to optimize the base station sites. This research shows that a proper approach in developing the individual structure and fitness function has crucial importance in solving practical base station siting problems with genetic algorithms.

Tabu Search for Frequency Assignment in Mobile Radio Networks

Abstract: The main goal of the Frequency Assignment Problem in mobile radio networks consists of assigning a limited number of frequencies to each radio cell in a cellular network while minimizing electromagnetic interference due to the reuse of frequencies. This problem, known to be NP-hard, is of great importance in practice since better solutions will allow a telecommunications operator to manage larger cellular networks. This paper presents a new Tabu Search algorithm for this application. The algorithm is tested on realistic and large problem instances and compared with other methods based on simulated annealing, constraint programming and graph coloring algorithms. Empirical evidence shows that the Tabu algorithm is very competitive by giving the best solutions to the tested instances.

A satellite-augmented cellular network concept

Abstract: Some next-generation personal communication systems propose the use of satellite systems for extending geographical coverage of cellular service. We pursue the idea of using satellite capacity to offload congestion within the area serviced by the terrestrial network. An integrated satellite-cellular network configuration is considered. The performance of this system is evaluated by means of an analytical model for a one-dimensional (highway) cellular system overlaid with satellite footprints and by means of simulation for a planar cellular network with satellite spot beam support. Under certain re-use assumptions, an improvement is found in the blocking performance of the integrated system over the Erlang-B blocking of a purely cellular circuit switched systems. This is achieved by efficient partitioning (static) of the total bandwidth into space and terrestrial segments. Major factors that influence performance, such as different reuse considerations on the satellite and cellular systems, cell size to footprint size ratios, admission control and call management policies, and changes in traffic patterns, are also investigated.

Multiple subscriber service profiles per mobile station in a cellular communications system

Abstract: The conventional one-to-one relationship between a mobile station (14) and its associated service profile (38) is broken to allow for plural service profiles to be selectively activated for use in connection with a single mobile station. These plural service profiles are stored in the home location register HLR (20) of the cellular network (10). A separate billing identification (44) is maintained for each service profile in order to allow for segregated billing of service charges incurred with respect to use of the mobile station. Selection of a certain one of the plural service profiles to be active for a mobile station is made through, for example, a default choice, a user selected choice, a feature code selected choice, or a schedule driven selected choice. The active one of the plural service profiles is down-loaded from the home location register, and applied in connection with both in-coming and out-going calls.