Showing papers on "Cellular network published in 2002"

Mobility increases the capacity of ad hoc wireless networks

Abstract: The capacity of ad hoc wireless networks is constrained by the mutual interference of concurrent transmissions between nodes. We study a model of an ad hoc network where n nodes communicate in random source-destination pairs. These nodes are assumed to be mobile. We examine the per-session throughput for applications with loose delay constraints, such that the topology changes over the time-scale of packet delivery. Under this assumption, the per-user throughput can increase dramatically when nodes are mobile rather than fixed. This improvement can be achieved by exploiting a form of multiuser diversity via packet relaying.

Connectivity in ad-hoc and hybrid networks

Abstract: We consider a large-scale wireless network, but with a low density of nodes per unit area. Interferences are then less critical, contrary to connectivity. This paper studies the latter property for both a purely ad-hoc network and a hybrid network, where fixed base stations can be reached in multiple hops. We assume here that power constraints are modeled by a maximal distance above which two nodes are not (directly) connected. We find that the introduction of a sparse network of base stations does significantly help in increasing the connectivity, but only when the node density is much larger in one dimension than in the other. We explain the results by percolation theory. We obtain analytical expressions of the probability of connectivity in the 1D case. We also show that at a low spatial density of nodes, bottlenecks are unavoidable. Results obtained on actual population data confirm our findings.

Mobile content delivery system

Abstract: A mobile content delivery system that optimizes the delivery of especially bandwidth-consuming content (or the flow of any peak-hour data traffic) in a way that best utilizes the free capacity in the radio network, thus enabling considerably more efficient usage of the radio capacity. It also allows new services and pricing structures to be used in the cellular network, that otherwise would not be possible. The class of delivery of message content can be selected by the user on a transaction basis, or subscription-based and pre-defined in a user profile. By choosing a scheduled delivery the user can receive the content at a fraction of the price compared to instant delivery, since the content is sent at a time when the network is least utilized.

WLAN-GPRS integration for next-generation mobile data networks

Abstract: The ongoing wireless LAN standardization and R&D activities worldwide, which target bit rates higher than 100 Mb/s, combined with the successful deployment of WLANs in numerous hotspots justify the fact that WLAN technology will play a key role in wireless data transmission. Cellular network operators have recognized this fact, and strive to exploit WLAN technology and integrate this technology into their cellular data networks. For this reason, there is currently a strong need for interworking mechanisms between WLANs and cellular data networks. We focus on these interworking mechanisms, which effectively combine WLANs and cellular data networks into integrated wireless data environments capable of ubiquitous data services and very high data rates in hotspot locations. We discuss the general aspects of integrated WLANs and cellular data networks, and we examine the generic interworking architectures that have been proposed in the technical literature. In addition, we review the current standardization activities in the area of WLAN-cellular data network integration. Moreover, we propose and explain two different interworking architectures, which feature different coupling mechanisms. Finally, we compare the proposed interworking architectures, and discuss their advantages and drawbacks.

Simulation and Software Radio for Mobile Communications

Abstract: Introduction. General Definition of Simulation Tools, Performance Evaluation for Digital Modulation Techniques. Orthogonal Frequency Division Multiplexing (OFDM) Transmission System. Code Division Multiplexing (CDM) Transmission System. Cellular Telecommunication System. Packet Telecommunications System. Software Radio Communication System.

Private cellular network with a public network interface and a wireless local area network extension

Abstract: A communication system ( 100 ) and method for coupling a wireless local area network (WLAN 128 ) to a public network ( 102 ) to enable communication between User Equipment terminals (UEs 130 ) associated with the WLAN and the public network. The public network ( 102 ) can include a GSM ( 110 ) and/or a 3G-network ( 114 ). The WLAN ( 128 ) can include a HiperLAN, HiperMAN, or 802.11 network. Preferably, the communication is voice communication, and the system ( 100 ) is configured to enable the UEs ( 130 ) to access supplementary services provided by the public network ( 102 ). Subscriber and security information for the UEs ( 102 ) can be provided to the public network ( 102 ) from a SIM ( 134 ) associated with each UE, or from an identity module ( 138 ) comprising either a private memory with information stored therein, or a card holder/reader holding cards with subscriber and security information for one or more UEs. Optionally, the system ( 100 ) further includes a private cellular network ( 122 ) the WLAN ( 128 ) also enables communication between the UEs ( 130 ) and the private cellular network.

P-MIP: paging extensions for mobile IP

Abstract: As the number of Mobile IP users grows, so will the signalling overhead associated with Internet mobility management in the core IP network. This presents a significant challenge to Mobile IP as the number of mobile devices scale-up. In cellular networks, registration and paging techniques are used to minimize the signalling overhead and optimize the mobility management performance. Currently, Mobile IP supports registration but not paging. In this paper, we argue that Mobile IP should be extended to support paging to improve the scalability of the protocol to handle large populations of mobile devices. To address this, we introduce P-MIP, a set of simple paging extensions for Mobile IP, and discuss the construction of paging areas, movement detection, registration, paging and data handling. We present analysis and simulation results for Mobile IP with and without paging extensions, and show that P-MIP can scale well supporting large numbers of mobile devices with reduced signalling under a wide variety of system conditions.

Capacity regions for wireless ad hoc networks

Abstract: We define and study capacity regions for ad hoc wireless networks with an arbitrary number of nodes and topology. These regions describe the set of achievable rate combinations between all source-destination pairs in the network under various transmission strategies, such as variable rate transmission, single hop or multihop routing, power control, and successive interference cancellation. With slight modifications, the developed formulation can handle multihop cellular networks, time-varying flat-fading channels and node mobility. Numerical results indicate that multihop routing, spatial reuse, and successive interference cancellation significantly increase the capacity of the network. On the other hand, gains by power control are not significant when the transmission rate is adapted to the channel SINR. We also find that time-varying flat fading and node mobility improve the performance of the network. Similar trends are observed for the special case of multihop cellular networks.

System, method and apparatus for federated single sign-on services

Abstract: The advent of new and sophisticated web services provided by Service Providers to users, services that individually require authentication of user and authorization of access, brings the needs for a new service to facilitate such authentication and access, a service referred to as Single Sign-On (SSO). The basic principle behind SSO is that users are authenticated once at a particular level, and then access all their subscribed services accepting that level of authentication. The present invention provides a system, method and apparatus wherein a cellular Federation of mobile network operators becomes an SSO authentication authority for subscribers of this Federation accessing Service Providers having such agreement with a mobile network operator of the Federation. In accordance with this invention, mobile network operators can leverage their operator-subscriber trust relationship in order to act as SSO authentication authority for those subscribers accessing Service Providers in a service domain other than the mobile network domain.

Planning effective cellular mobile radio networks

Abstract: This paper deals with the automatic selection and configuration of base station sites for mobile cellular networks. An optimization framework based on simulated annealing is used for site selection and for base-station configuration. Realistic path-loss estimates incorporating terrain data are used. The configuration of each base station involves selecting antenna type, power control, azimuth, and tilt. Results are presented for several design scenarios with between 250 and 750 candidate sites and show that the optimization framework can generate network designs with desired characteristics such as high area coverage and high traffic capacity. The work shows that cellular network design problems are tractable for realistic problem instances.

Methods and apparatus for mobile station location estimation

Abstract: Methods and apparatus for estimating mobile station location include receiving reported signal strengths or other attachment indicator values from a mobile station. The reported signal strengths are compared with characteristic received signal strength values in a coverage area of a mobile network. A mobile switching center determines if a local function is requested and initiates a location estimation process by a mobile location module (MLM). The MLM receives the reported signal strength contours associated with the attachment points. Based on a comparison of the reported attachment indicator values with characteristic values, the MLM provides a mobile location estimate.

Location based services for mobile communication terminals

Abstract: The present inventions relate to methods of providing services in dependence on the geographical location of mobile terminals in a cellular network. The inventions relate further to mobile communication terminals for use with a cellular network that are able to receive or provide services in dependence of their geographical position obtained through interaction with the cellular network.

A method and apparatus for supporting cellular data communication to roaming mobile telephony devices

Abstract: A cellular data communication interfacing apparatus, for association with a mobile network and for supporting cellular data communication to roaming mobile telephony devices, comprises a data request analyzer, a service network selector, and an interfacing engine. Each of the roaming telephony devices is associated with a respective home network and a service profile specifying service networks providing data services to the device. The data request analyzer analyzes data requests from the roaming mobile. The service network selector uses the request analyses together with the device service profiles to select a corresponding service network. The interfacing engine introduces the devices to the service networks, directs the data requests to the service networks, and directs the corresponding data responses from the service networks to the requesting roaming mobile devices.

Mobile network evolution: a revolution on the move

Abstract: This article gives an overview of the evolution in the mobile communications world. The uptake of 2G technologies has been tremendous, even though several systems exist that are not interoperable. 3G will bring some convergence, but will not achieve the goal of a single global technology. At the network level, IP is becoming more important. In hot spot environments, WLAN is bringing a complementary technology toward cellular.

Analysis of a metropolitan-area wireless network

Abstract: We analyze a seven-week trace of the Metricom metropolitan-area packet radio wireless network to find how users take advantage of a mobile environment. Such understanding is critical for planning future large-scale mobile network infrastructures. Amongst other results, we find that users typically use the radios during the day and evening. Of the users who move around during the trace (over half), we find that the more locations a user visits on a daily basis, the closer together, on average, those locations are. While these results are only known to be valid for this particular network, we hope future analysis of other networks will add to a growing understanding of mobile network behavior.

A heterogeneous routing protocol based on a new stable clustering scheme

Abstract: A mobile ad hoc network (MANET) is usually assumed to be homogeneous, where each mobile node shares the same radio capacity. However, a homogeneous ad hoc network suffers from poor scalability. Research has demonstrated its performance bottleneck both theoretically and through simulation experiments. Building a physically hierarchical ad hoc network is a very promising way to achieve scalability. Routing is critical to operate such a hierarchical structure efficiently. Previous research has been solely focusing on extending popular routing schemes developed for the homogeneous ad hoc network. We propose a new heterogeneous routing protocol specifically designed for the hierarchical ad hoc network. We also present a new active clustering scheme to help build a stable hierarchical structure, which is fundamental to heterogeneous routing protocols. Simulation results using GloMoSim show that our routing and clustering scheme gives good performance. The results also provide some insight into new possible designs of routing protocols and mobile network architectures for MANETs when large scale is desired.

Efficient and guaranteed service coverage in partitionable mobile ad-hoc networks

Abstract: In wireless ad-hoc networks, the network topology changes dynamically and unpredictably due to node mobility. Such topological dynamics are further exacerbated by the natural grouping behavior in the mobile user's movement, which leads to frequent network partitioning. Network partitioning poses significant challenges to the provisioning of centralized services in ad-hoc networks, since partitioning disconnects many mobile users from the central server. We propose a collection of novel run-time algorithms that adaptively ensure the centralized service is available to all mobile nodes during network partitioning, while minimizing the number of servers required. The network-wide service coverage is achieved by partition prediction and service replication on the servers, and assisted by distributed service selection on regular mobile nodes. Simulation results show that our algorithm efficiently achieves guaranteed service coverage to all nodes. To the best of our knowledge, there have been no similar approaches that use partition prediction to provision centralized services adaptively in partitionable mobile ad-hoc networks.

Integration of pricing with call admission control to meet QoS requirements in cellular networks

Abstract: Call admission control (CAC) plays a significant role in providing the desired quality of service (QoS) in cellular networks. We investigate the role of pricing as an additional dimension of the call admission control process in order to efficiently and effectively control the use of wireless network resources. First, we prove that, for a given wireless network, there exists a new call arrival rate which can maximize the total utility of users while maintaining the required QoS. Based on this result and observation, we propose an integrated pricing and call admission control scheme where the price is adjusted dynamically based on the current network conditions in order to alleviate the problem of congestion. Our proposed integrated approach implicitly implements a distributed user-based prioritization mechanism by providing negative incentives according to the current network conditions and therefore shaping the aggregate traffic in the network. We compare the performance of our approach in terms of congestion prevention, achievable total user utility, and obtained revenue, with the corresponding results of conventional systems where pricing is not taken into consideration in the call admission control process. These performance results verify the considerable improvement that can be achieved by the integration of pricing in the call admission control process in cellular networks.

Intersystem handover of a mobile terminal

Abstract: The invention relates to a method for performing an intersystem handover of a mobile terminal (5) accessing a communication network via a radio access network (1) of a first type. The communication network comprises at least this radio access network (1) of this first type and a radio access network (2) of a second type. In order to enable an access to the communication network with a radio access technology required or desired by the mobile terminal (5), the intersystem handover is initiated by a transmission of the mobile terminal (5) to the communication network, which transmission comprises information indicating that an intersystem handover from the radio access network (1) of the first type to the radio access network (2) of said second type should be performed. The invention equally relates to a corresponding mobile terminal, to a corresponding communication network, to a corresponding communication system, to a network element of a communication network and to a web switch of a communication system.

Method and apparatus for splitting control and media content from a cellular network connection

Abstract: This invention provides a system and method for splitting control and media content signals of a cellular network connection of a mobile station. A mobile station engages in a WAP browsing session with a cellular network connection over an air interface. As a user moves into coverage area of an access point, another browsing session is established between the mobile station and a non-cellular network connection. More specifically, the user's WAP browsing session with a cellular network connection is upgraded to a Web browsing session with a non-cellular network connection. The present invention permits a user to control a Web browser on a remote device by providing user input to the mobile station. In particular, a media content portion of the cellular network connection is split and rerouted to the remote device, and a control portion of the cellular network connection is split and rerouted either via the non-cellular network connection or via the cellular network connection.

Rate-based borrowing scheme for QoS provisioning in multimedia wireless networks

Abstract: Now that cellular networks are being called upon to support real-time interactive multimedia traffic such as video teleconferencing, these networks must be able to provide their users with quality-of-service (QoS) guarantees. Although the QoS provisioning problem arises in wireline networks as well, mobility of hosts, scarcity of bandwidth, and channel fading make QoS provisioning a challenging task in wireless networks. It has been noticed that multimedia applications can tolerate and gracefully adapt to transient fluctuations in the QoS that they receive from the network. The management of such adaptive multimedia applications is becoming a new research area in wireless networks. As it turns out, the additional flexibility afforded by the ability of multimedia applications to tolerate and adapt to transient changes in the QoS parameters can be exploited by protocol designers to significantly improve the overall performance of wireless systems. The main contribution of this paper is to propose a novel, rate-based, borrowing scheme for QoS provisioning in high-speed cellular networks carrying multimedia traffic. Our scheme attempts to allocate the desired bandwidth to every multimedia connection originating in a cell or being handed off to the cell. The novelty of our scheme is that, in case of insufficient bandwidth, in order not to deny service to requesting connections (new or hand-off), bandwidth will be borrowed, on a temporary basis, from existing connections. Our borrowing scheme guarantees that no connection gives up more than its fair share of bandwidth, in the sense that the amount of bandwidth borrowed from a connection is proportional to its tolerance to bandwidth loss. Importantly, our scheme ensures that the borrowed bandwidth is promptly returned to the degraded connections. Extensive simulation results show that our rate-based QoS provisioning scheme outperforms the best previously known schemes in terms of call dropping probability, call blocking probability, and bandwidth utilization.

Movable access points and repeaters for minimizing coverage and capacity constraints in a wireless communications network and a method for using the same

Abstract: A system and method for improving the ability of a wireless packet switched data communications network (Fig. 1) to provide service to mobile user terminals (118). It employs a mobile access point (132) adapted to provide a mobile wireless user terminal (118) with access to packet-switched communications network. Mobile access point (132) can be mounted to a mobile vehicle (146) and receives substantially constant power fom the vehicle and is adapted to transmit and receive communications signals to and from wireless user terminals (118), fixed access points (106 and 108) and other networks (124, 128, 148, 150, and 152) and wireless terminals (118). Mobile access point (132) includes at least one or more transceivers supporting multiple wireless communication protocols.

Power management system for a mobile unit by reduced neighbor cell scanning

Abstract: A power management system for a mobile unit wherein the frequency of scanning a neighboring cell may be controlled. A mobile unit consumes power in standby mode by periodically scanning the base station in each neighboring cell to determine which base stations are providing a usable signal. When the signal provided by the mobile unit's servicing base station diminishes, the mobile unit informs the cellular network of the base stations providing usable signals to assist in the handover. By detecting the rate of change of the signal strength received from a base station, the mobile unit may change the scanning rate of each neighboring cell. Alternatively, the mobile unit can estimate the relative speed it is traveling through a cell. If traveling slowly through the cell or if the signal strength is not changing over time, the need for a rapid handover diminishes. The mobile unit may also increase the scanning rate if traveling rapidly through the cell.

Commanding handover between differing radio access technologies

Abstract: A dual mode mobile terminal (MT) (30) is capable of communicating (e.g., with a core network) either via a first radio access network (12) having a first type radio access technology (GSM) or a second radio access network (14) having a second type radio access technology (UTRAN). When conditions warrant, a network node (26) prepares a radio access technology (RAT) handover message (3-9) for transmission to the equipment unit (UE) in conjunction with handover of the mobile terminal (MT) from the first radio access network to the second radio access network, and an associated change of operation mode of the mobile terminal (MT) from the first mode to the second mode. In accordance with the present invention, a radio access technology handover message includes a first information element representative of a first parameter from which a value of a second parameter can be derived so that the second parameter need not be included as a separate information element in the radio access technology handover message. Not including the second parameter as a separate element in the radio access technology handover message facilitates non-segmentation of the radio access technology handover message. In one aspect of the invention, the radio access technology handover message is a RRC Handover to UTRAN message; the first parameter is a Serving-Radio Network Temporary Identifier (S-RNTI 2); and, the second parameter is an information element which facilitates distribution of load and transmission of traffic in the radio access network (e.g., a Default DPCH Offset Value).

Adaptive bandwidth reservation and admission control in QoS-sensitive cellular networks

Abstract: How to keep the probability of hand-off drops within a prespecified limit is a very important quality-of-service (QoS) issue in cellular networks because mobile users should be able to maintain ongoing sessions even during their hand-off from one cell to another. We design and evaluate predictive and adaptive schemes for bandwidth reservation for the hand-offs of ongoing sessions 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 probabilistically predict 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 tractional bandwidths of the expected hand-offs within a mobility-estimation time window. Three different admission-control schemes for new connection requests using this bandwidth reservation are proposed. We also consider variations that utilize the path/location information available from the car navigation system or global positioning system. Finally, we evaluate the performance of the proposed schemes extensively to show that they meet our design goal and outperform the static reservation scheme under various scenarios.

Self-organizing packet radio ad hoc networks with overlay (SOPRANO)

Abstract: The SOPRANO project involves a novel adaptive and scalable wireless network architecture utilizing a mixture of cellular and multihop packet radio system topologies with the potential to support a variety of applications including high-data rate Internet and multimedia traffic at a reasonable degree of implementation complexity. This article discusses the potential benefits of this structure and addresses several relevant issues necessary to support such a network. More specifically, it focuses on connection establishment and self-organization, investigates the formulation of an optimum transmission strategy, and examines some of the techniques by which we can augment the capacity or enhance the system performance in this multihop network. We also present capacity bounds that illustrate how these techniques help in trading off conserved power for a multifold capacity advantage.

Addressing and routing in hexagonal networks with applications for tracking mobile users and connection rerouting in cellular networks

Abstract: Nodes in a hexagonal network are placed at the vertices of a regular triangular tessellation, so that each node has up to six neighbors. The network is proposed as an alternative interconnection network to a mesh connected computer (with nodes serving as processors) and is used also to model cellular networks where nodes are the base stations. In this paper, we propose a suitable addressing scheme for nodes (with two variants), derive a formula for distance between nodes, and present a very simple and elegant routing algorithm. This addressing scheme and corresponding routing algorithm for hexagonal interconnection are considerably simpler than previously proposed solutions. We then apply the addressing scheme for solving two problems in cellular networks. With the new scheme, the distance between the new and old cell to which a mobile phone user is connected can be easily determined and coded with three integers, one of them being zero. Further, in order to minimize the wireless cost of tracking mobile users, we propose hexagonal cell identification codes containing three, four, or six bits, respectively, to implement a distance based tracking strategy. These schemes do not have errors in determining cell distance in existing hexagonal based cellular networks. Another application is for connection rerouting in cellular networks during a path extension process.

Designing LoL@, a Mobile Tourist Guide for UMTS

Abstract: Modern lifestyle corresponds with high personal mobility. People want to work or use leisure-time applications while on the road. Modern mobile communications systems allow to meet these requirements for the first time. Advanced new features like user positioning allow sophisticated applications that are not possible in the fixed Internet or traditional cellular networks. Still, application development for the Mobile Internet is a complex task. Users have special demands because of the mobile environment. Stringent technical constraints are imposed by mobile networks and mobile devices.In this paper we present a prototype of a mobile application for UMTS. It is called [email protected] (Local Location Assistant) and implements a tourist guide for users in the city of Vienna. We discuss user interaction and interface design, design process, and technical solutions used to implement the application. Because of the initial lack of powerful PDAs, currently a laptop is used as terminal.

Access control system, access control method and devices suitable therefore

Abstract: An access control system comprises a plurality of access control devices in each of which is stored an access code. Specific access codes and access rights for a plurality of access control devices are transmitted from an access control central unit over a mobile radio network to the mobile communication terminal of a user. Transmitted to the mobile communication terminal by an access control device to be passed is an access control device identification. In the mobile communication terminal, on the basis of the received identification, the access code and the access rights for the access control device to be passed are determined, and are transmitted to the access control device. The access control device clears the user for access if the received access rights suffice and the received access code agrees with the stored access code.