Showing papers on "Cellular network published in 2003"

Cross-layer design for wireless networks

Abstract: As the cellular and PCS world collides with wireless LANs and Internet-based packet data, new networking approaches will support the integration of voice and data on the composite infrastructure of cellular base stations and Ethernet-based wireless access points. This article highlights some of the past accomplishments and promising research avenues for an important topic in the creation of future wireless networks. We address the issue of cross-layer networking, where the physical and MAC layer knowledge of the wireless medium is shared with higher layers, in order to provide efficient methods of allocating network resources and applications over the Internet. In essence, future networks will need to provide "impedance matching" of the instantaneous radio channel conditions and capacity needs with the traffic and congestion conditions found over the packet-based world of the Internet. Furthermore, such matching will need to be coordinated with a wide range of particular applications and user expectations, making the topic of cross-layer networking increasingly important for the evolving wireless buildout.

Capacity regions for wireless ad hoc networks

Abstract: We define and study capacity regions for wireless ad hoc 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 (SIC). Multihop cellular networks and networks with energy constraints are studied as special cases. With slight modifications, the developed formulation can handle node mobility and time-varying flat-fading channels. Numerical results indicate that multihop routing, the ability for concurrent transmissions, and SIC significantly increase the capacity of ad hoc and multihop cellular networks. On the other hand, gains from power control are significant only when variable-rate transmission is not used. Also, time-varying flat-fading and node mobility actually improve the capacity. Finally, multihop routing greatly improves the performance of energy-constraint networks.

On the capacity of hybrid wireless networks

Abstract: This paper involves the study of the throughput capacity of hybrid wireless networks. A hybrid network is formed by placing a sparse network of base stations in an ad hoc network. These base stations are assumed to be connected by a high-bandwidth wired network and act as relays for wireless nodes. They are not data sources nor data receivers. Hybrid networks present a tradeoff between traditional cellular networks and pure ad hoc networks in that data may be forwarded in a multihop fashion or through the infrastructure. It has been shown that the capacity of a random ad hoc network does not scale well with the number of nodes in the system. In this work, we consider two different routing strategies and study the scaling behavior of the throughput capacity of a hybrid network. Analytical expressions of the throughput capacity are obtained. For a hybrid network of n nodes and m base stations, the results show that if m grows asymptotically slower than √n, the benefit of adding base stations on capacity is insignificant. However, if m grows faster than √n, the throughput capacity increases linearly with the number of base stations, providing an effective improvement over a pure ad hoc network. Therefore, in order to achieve nonnegligible capacity gain, the investment in the wired infrastructure should be high enough.

The shared wireless infostation model: a new ad hoc networking paradigm (or where there is a whale, there is a way)

Abstract: In wireless ad hoc networks, capacity can be traded for delay. This tradeoff has been the subject of a number of studies, mainly concentrating on the two extremes: either minimizing the delay or maximizing the capacity. However, in between these extremes, there are schemes that allow instantiations of various degrees of this tradeoff. Infostations, which offer geographically intermittent coverage at high speeds, are one such an example. Indeed, through the use of the Infostation networking paradigm, the capacity of a mobile network can be increased at the expense of delay. We propose to further extend the Infostation concept by integrating it with the ad hoc networking technology. We refer to this networking model as the Shared Wireless Infostation Model (SWIM). SWIM allows additional improvement in the capacity-delay tradeoff through a moderate increase in the storage requirements. To demonstrate how SWIM can be applied to solve a practical problem, we use the example of a biological information acquisition system - radio-tagged whales - as nodes in an ad hoc network. We derive an analytical formula for the distribution of end-to-end delays and calculate the storage requirements. We further extend SWIM by allowing multi-tiered operation; which in our biological information acquisition system could be realized through seabirds acting as mobile data collection nodes.

TCP Veno: TCP enhancement for transmission over wireless access networks

Abstract: Wireless access networks in the form of wireless local area networks, home networks, and cellular networks are becoming an integral part of the Internet. Unlike wired networks, random packet loss due to bit errors is not negligible in wireless networks, and this causes significant performance degradation of transmission control protocol (TCP). We propose and study a novel end-to-end congestion control mechanism called TCP Veno that is simple and effective for dealing with random packet loss. A key ingredient of Veno is that it monitors the network congestion level and uses that information to decide whether packet losses are likely to be due to congestion or random bit errors. Specifically: (1) it refines the multiplicative decrease algorithm of TCP Reno-the most widely deployed TCP version in practice-by adjusting the slow-start threshold according to the perceived network congestion level rather than a fixed drop factor and (2) it refines the linear increase algorithm so that the connection can stay longer in an operating region in which the network bandwidth is fully utilized. Based on extensive network testbed experiments and live Internet measurements, we show that Veno can achieve significant throughput improvements without adversely affecting other concurrent TCP connections, including other concurrent Reno connections. In typical wireless access networks with 1% random packet loss rate, throughput improvement of up to 80% can be demonstrated. A salient feature of Veno is that it modifies only the sender-side protocol of Reno without changing the receiver-side protocol stack.

Downlink capacity evaluation of cellular networks with known-interference cancellation

Abstract: Recently, the capacity region of a multiple-input multiple-output (MIMO) Gaussian broadcast channel, with Gaussian codebooks and known-interference cancellation through dirty paper coding, was shown to equal the union of the capacity regions of a collection of MIMO multiple-access channels. We use this duality result to evaluate the system capacity achievable in a cellular wireless network with multiple antennas at the base station and multiple antennas at each terminal. Some fundamental properties of the rate region are exhibited and algorithms for determining the optimal weighted rate sum and the optimal covariance matrices for achieving a given rate vector on the boundary of the rate region are presented. These algorithms are then used in a simulation study to determine potential capacity enhancements to a cellular system through known-interference cancellation. We study both the circuit data scenario in which each user requires a constant data rate in every frame and the packet data scenario in which users can be assigned a variable rate in each frame so as to maximize the long-term average throughput. In the case of circuit data, the outage probability as a function of the number of active users served at a given rate is determined through simulations. For the packet data case, long-term average throughputs that can be achieved using the proportionally fair scheduling algorithm are determined. We generalize the zero-forcing beamforming technique to the multiple receive antennas case and use this as the baseline for the packet data throughput evaluation.

A charging and rewarding scheme for packet forwarding in multi-hop cellular networks

Abstract: In multi-hop cellular networks, data packets have to be relayed hop by hop from a given mobile station to a base station and vice-versa. This means that the mobile stations must accept to forward information for the benefit of other stations. In this paper, we propose an incentive mechanism that is based on a charging/rewarding scheme and that makes collaboration rational for selfish nodes. We base our solution on symmetric cryptography to cope with the limited resources of the mobile stations. We provide a set of protocols and study their robustness with respect to various attacks. By leveraging on the relative stability of the routes, our solution leads to a very moderate overhead.

Cellular telephone-based transaction processing

Abstract: A retail transaction system provides enhanced customer convenience and increased transaction security by sending transaction information to a cellular network provider via a customer's digital cellular phone For example, a fuel dispenser is equipped with a communications link allowing direct communications to a customer's cellular phone When a customer desires to conduct a transaction using the fuel dispenser, the fuel dispenser transmits select information to the customer's cellular telephone using this communications link A telephone number is included in the select information When the customer presses send, or otherwise causes their telephone to dial the number transferred from the fuel dispenser, the select information along with any additional customer information is sent to the cellular network This information is used by the network to authorize a purchase transaction for the customer, such authorization information returned to the fueling station at which the fuel dispenser is located via a cellular link For enhanced security, the customer may be required to input their PIN in order to complete the transaction Notably, the PIN and the remainder of the transaction information sent from the customer phone to the cellular network is intrinsically secure due to the digital encryption employed by the digital cellular protocol Optionally, the system may be configured to cause the customer's cellular phone to automatically dial the number transferred by the fuel dispenser This capability may be enabled at the customer's option The system may be extended to other retail systems including in-store point-of-sale systems (POS)

A micro-payment scheme encouraging collaboration in multi-hop cellular networks

Abstract: We propose a micro-payment scheme for multi-hop cellular networks that encourages collaboration in packet forwarding by letting users benefit from relaying others’ packets. At the same time as proposing mechanisms for detecting and rewarding collaboration, we introduce appropriate mechanisms for detecting and punishing various forms of abuse. We show that the resulting scheme – which is exceptionally light-weight – makes collaboration rational and cheating undesirable.

Extension of a local area phone system to a wide area network

Abstract: A soft switch providing wireless PBX voice services to a local area network (WLAN) is used to extend PBX functionality to the cellular domain. A dual mode remote unit is capable of receiving signals both in the cellular system as well as the WLAN. The cellular system is comprised of a data-bearing path and a voice-bearing path. When the dual mode remote unit is within the WLAN, it communicates both voice over IP(VoIP) signaling as well as session initiation protocol (SIP) control signaling over the WLAN. When the remote unit is outside the WLAN, it communicates voice signaling over the voice-bearing path of the cellular network using a standard cellular voice channel. In parallel, it uses the data-bearing path of the cellular network to transmit SIP control signaling.

Relayer selection strategies in cellular networks with peer-to-peer relaying

Abstract: We consider a TDMA cellular multihop network where relaying - via wireless terminals that have a good communication link to the base station - is used as a coverage enhancement technique. Provided that the subscriber density is not very low, relaying via wireless terminals can have a significant impact on coverage, capacity, and throughput. This is mainly due to the fact that the signals only have to travel through shorter distances and/or improved paths. In this work, we investigated the effects of relaying node selection strategies (essentially a routing issue) and maximum relayer transmit power level on coverage. Our simulation results show that with a very modest level of relaying node transmit power and with some moderate intelligence incorporated in the relaying node selection scheme, the (high data rate) coverage can be improved significantly through two-hop relaying without consuming any additional bandwidth.

System and method for offering geocentric-based incentives and executing a commercial transaction via a wireless device

Abstract: A system and method of obtaining geocentric or location-specific information over a cellular telephone connection. A user enters an information access code (24) into his remote device (1), which has cell phone capability (2) and a GPS receiver (6), which sends an incentive request (18) (including the access code (24), a user identification code (20), and GPS location data (22)) to an information server (16) via the cellular network (12). The information to server (16) uses the request to retrieve an incentive record as a function of the access code (24) and the GPS location data (22), and then transmits the incentive record back to the remote device (1) via the cellular telephone network (12). The remote device provides the incentive record to the user via a user interface (4) such as a display screen. The incentive record will have information related to a merchant offering the incentive for a product of interest to the user that is located in a vicinity of the remote device, since the information server is aware of the location of the user due to the GPS data it receives.

Notification alarm transfer methods, system, and device

Abstract: A method for transferring data may include receiving data from a monitoring device, determining whether the subject being monitored has a condition that may require attention, and sending a notification message to a portable electronic device that is designed to be carried by a caregiver if such a condition exists. The notification message may be sent using one or both of a first wireless data transfer method and a second wireless data transfer method. The system may use both methods to communicate with one device or may use the first method to communicate with a first device and the second method to communicate with a second device. The portable electronic device may include two wireless transceivers such as a transceiver designed to connect the device to a local area network of a facility and a transceiver designed to connect the device to a cellular network.

Connection architecture for a mobile network

Abstract: A real-time communication architecture establishes a continuous connection between an enterprise network and a communication management system. The connection is continuously held open allowing mobile devices real-time access to enterprise email systems. The real-time communication architecture can support an entire enterprise email system or individual email users. The foregoing and other objects, features and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment of the invention which proceeds with reference to the accompanying drawings.

Method and system for cellular network traffic redirection

Abstract: A system and apparatus for redirecting wireless network traffic. Embodiments include determining when a roaming mobile station (204) initiates a registration attempt with a non-preferred network (506) and causing the roaming mobile station to initiate a registration attempt with a preferred network (504). Embodiments further include a traffic redirection network entity including a traffic redirection node (102b), a traffic redirection application (102c), and a traffic redirection probe. Embodiments also include redirecting traffic after a mobile station has registered with a non-preferred network.

QoS provisioning in cellular networks based on mobility prediction techniques

Abstract: In cellular networks, QoS degradation or forced termination may occur when there are insufficient resources to accommodate handoff requests. One solution is to predict the trajectory of mobile terminals so as to perform resource reservations in advance. With the vision that future mobile devices are likely to be equipped with reasonably accurate positioning capability, we investigate how this new feature may be used for mobility predictions. We propose a mobility prediction technique that incorporates road topology information, and describe its use for dynamic resource reservation. Simulation results are presented to demonstrate the improvement in reservation efficiency compared with several other schemes.

Ad hoc networking of terminals aided by a cellular network

Abstract: A fast and secure ad hoc communication system is established between terminals with the aid of a network. Terminals equipped with a non-cellular interface may establish a high data rate peer-to-peer or multi-hop ad hoc connection with the support of a cellular network. The cellular network may provide signaling for user authentication, peer identification, key distribution for a secure non-cellular connection set-up, radio resources management messages, routing assistance information, as well as charging and billing for the service. A non-cellular link may be used for fast and secure ad hoc communication between the terminals. Signaling may be transported either over a non-cellular access network or, using dual-mode terminals, over the cellular RAN. A combination of the signaling transports is also possible.

Beyond 3G: vision, requirements, and enabling technologies

Abstract: This article introduces the vision and requirements for future development of mobile communications systems, and discusses several key enabling technologies such as modulation and multiple access schemes, multiple antenna techniques, and an IP-based network, considered important to realize this vision in real-world systems.

Registration of a wlan as a umts routing area for wlan-umts interworking

Abstract: A system for employing a wireless local (Fig. 4) area network (WLAN) (14) as a cellular network routing area includes a cellular network (12), which is capable of determining a location where a service request is made. The cellular (12) network includes a packet-based support node B, which determines if the request can be serviced through a WLAN (14), which is identified in the cellular network (12) as a routing area. Packet data protocol (PDP) context is maintained while servicing the request using the WLAN (14) to provide smooth interworking between the WLAN (14) and the cellular network (12).

A method and apparatus for wireless remote telemetry using ad-hoc networks

Abstract: A wireless remote telemetry system uses low-cost, low-power ad-hoc networks to provide flexible reading and control of remote devices. In an embodiment applicable to a utility service, consumption of electrical power among a population of customers is measured by a utility metering system having ad-hoc network communication capability. The remote metering unit transmits information over an ad-hoc network to one or more intermediate communication units or hops. The intermediate communication units or hops include a mobile unit, a mobile base unit, a subscriber home computer, and a home base unit. Each of these hops may co-exist in the same large-scale system. The intermediate communication units transfer the received information to a central controller through multi-hop ad-hoc networks or cellular networks, according to intelligent planning by the wireless infrastructure or the central unit.

Method and apparatus for performing inter-technology handoff from WLAN to cellular network

Abstract: A method, system and computer program are disclosed to perform a low latency inter-technology handoff of a MN from a WLAN to a cellular network. The method includes transmitting a Bearer Context from the MN for use by the cellular network, the Bearer Context containing information required to establish access network bearers in the cellular network for an ongoing Internet session of the MN; and responding to the Bearer Context with a Router Advertisement that is forwarded to the MN. The Bearer Context may be piggybacked on another message, or it may be sent as a separate message. The Bearer Context includes information expressive of: (a) a QoS requirement of an ongoing application or applications of the MN; (b) a unique identity of the MN that is recognizable by the cellular network; (c) parameters to facilitate the creation of a Point-to-Point Protocol state in the cellular network; and (d) parameters to enable establishment of packet filters in the cellular network. The method also includes authenticating and authorizing with the target cellular network for the purpose of executing handoff.

GPPS: A Gaussian Process Positioning System for Cellular Networks

Abstract: In this article, we present a novel approach to solving the localization problem in cellular networks. The goal is to estimate a mobile user's position, based on measurements of the signal strengths received from network base stations. Our solution works by building Gaussian process models for the distribution of signal strengths, as obtained in a series of calibration measurements. In the localization stage, the user's position can be estimated by maximizing the likelihood of received signal strengths with respect to the position. We investigate the accuracy of the proposed approach on data obtained within a large indoor cellular network.

Performance analysis of a preemptive and priority reservation handoff scheme for integrated service-based wireless mobile networks

Abstract: We propose an analytical model for integrated real-time and non-real-time services in a wireless mobile network with priority reservation and preemptive priority handoff schemes. We categorize the service calls into four different types, namely, real-time and non-real-time service originating calls, and real-time and non real-time handoff service request calls. Accordingly, the channels in each cell are divided into three parts: one is for real-time service calls only, the second is for non-real-time service calls only, and the last one is for overflow of handoff requests that cannot be served in the first two parts. In the third group, several channels are reserved exclusively for real-time service handoffs so that higher priority can be given to them. In addition, a realtime service handoff request has the right to preempt non-real-time service in the preemptive priority handoff scheme if no free channels are available, while the interrupted non-real-time service call returns to its handoff request queue. The system is modeled using a multidimensional Markov chain and a numerical analysis is presented to estimate blocking probabilities of originating calls, forced termination probability, and average transmission delay. This scheme is also simulated under different call holding time and cell dwell time distributions. It is observed that the simulation results closely match the analytical model. Our scheme significantly reduces the forced termination probability of real-time service calls. The probability of packet loss of non-real-time transmission is shown to be negligibly small, as a non-real-time service handoff request in waiting can be transferred from the queue of the current base station to another one.

Mobile Radio Communications

Abstract: Mobile communications has been of interest since the earliest days of wireless communications. First applications involved ship-to-shore and ship-to-ship telegraphy as well as telegraphy to moving trains. The development of AM radio, and later FM radio, resulted in mobile voice communication systems. The development of the cellular radio concept gave to rise to mobile telephones that were both practical and inexpensive. The growth of the cellular telephone industry exceeded all expectations and, in many environments, the bulk of telephone traffic is now handled by wireless cellular systems. This article details this history and describes the essential features of mobile radio systems, including the cellular concept, mobile radio channels, and multiple access techniques. First, second and third generation commercial cellular systems are discussed and their capabilities are compared. Keywords: wireless communications; mobile communications; cellular systems; multiple access systems; CDMA; time-division multiple access; frequency-division multiple access

Access Pricing under Competition: An Application to Cellular Networks

Abstract: A new class of access pricing problems is analyzed in which upstream firms compete for customers and access to these customers is required by downstream markets. Using fixed–to–cellular calls as an example, a model is presented which shows that the determination of cellular termination charges is quite different to standard access pricing problems. Competition between cellular firms leads to access prices being set either at, or above, the monopoly level. Applications are given for other market settings, including the termination of long–distance calls on competing local exchange networks and the setting of interchange fees in payment systems.

Methods and apparatuses for measuring frequencies of basestations in cellular networks using mobile GPS receivers

Abstract: Methods and apparatuses for frequency synchronizing basestations in a cellular communication system. In one aspect of the invention, a method to predict a timing of transmission of a basestation in a cellular communication system includes: receiving a first time tag for a first timing marker in a first cellular signal transmitted from the basestation; receiving a second time tag of a second timing marker in a second cellular signal transmitted from the basestation; and computing a frequency related to the basestation using the first and second time tags. Each of the time tags are determined using at least one satellite positioning system signal received at a mobile station which receives the corresponding time marker.

Access Pricing Under Competition: An Application to Cellular Networks

Abstract: A new class of access pricing problems is analyzed in which upstream firms compete for customers and access to these customers is required by downstream markets. Using fixed-to-cellular calls as an example, a model is presented which shows that the determination of cellular termination charges is quite different to standard access pricing problems. Competition between cellular firms leads to access prices being set either at, or above, the monopoly level. Applications are given for other market settings, including the termination of long-distance calls on competing local exchange networks and the setting of interchange fees in payment systems.

Frequency assignment for IEEE 802.11 wireless networks

Abstract: The IEEE 80211 standard specifies both radio and MAC protocol design We observe that its CSMA protocol helps avoid much of co-channel interference by sharing radio resources in time at the potential expense of degraded network performance Due to the coupling between the physical and MAC layers, conventional frequency allocation methods for typical cellular networks cannot be applied directly to the 80211 networks In this paper, by focusing on interactions among access points, we formulate the channel assignment problem for the 80211 network, considering the traffic load at the MAC layer, and prove that the problem is NP-complete In light of computational complexity, a heuristic algorithm is proposed and analyzed The algorithm is then applied to two cellular settings with known optimal assignments for verification For one of the settings, the proposed technique generates the optimal channel assignment As for the second case of a large network, although only a suboptimal solution is obtained by the algorithm, it is shown to be excellent Thus, as the 80211 networks are widely deployed, the proposed method can serve as a valuable tool for frequency planning of networks with non-uniform coverage and load

System, method and apparatus for automated collective mobile robotic vehicles used in remote sensing surveillance

Abstract: A system is described for remote sensing surveillance by configuring groups of automated mobile robotic vehicles (MRVs). The collection of MRVs have sensors that feed information to a central network node. As the MRVs interact with the environment, the mobile network adapts in real time by reconfiguring its spatial positions. This system, and the methods and apparatus involved therein, are applied to reconnaissance missions in order to collect information in remote hostile environments.

Multi-hop intelligent relaying method and apparatus for use in a frequency division duplexing based wireless access network

Abstract: A multi-hop relaying method and apparatus used in a cellular network. The multi-hop transmission scheme utilizes intelligent relays within a conventional cellular system having at least one base station, one or more intelligent relays, and user equipment elements. The method includes selecting the strongest pilot signal from among the base stations and intelligent relays, reporting such to the base station, distributing an active user list to the relays along with scheduling and routing information via a relay control channel, and transmitting data according to a respective active user based upon the pilot signal strength to maximize coverage and capacity over the cellular system.