Showing papers on "Base station published in 2000"

Energy-efficient communication protocol for wireless microsensor networks

Abstract: Wireless distributed microsensor systems will enable the reliable monitoring of a variety of environments for both civil and military applications. In this paper, we look at communication protocols, which can have significant impact on the overall energy dissipation of these networks. Based on our findings that the conventional protocols of direct transmission, minimum-transmission-energy, multi-hop routing, and static clustering may not be optimal for sensor networks, we propose LEACH (Low-Energy Adaptive Clustering Hierarchy), a clustering-based protocol that utilizes randomized rotation of local cluster based station (cluster-heads) to evenly distribute the energy load among the sensors in the network. LEACH uses localized coordination to enable scalability and robustness for dynamic networks, and incorporates data fusion into the routing protocol to reduce the amount of information that must be transmitted to the base station. Simulations show the LEACH can achieve as much as a factor of 8 reduction in energy dissipation compared with conventional outing protocols. In addition, LEACH is able to distribute energy dissipation evenly throughout the sensors, doubling the useful system lifetime for the networks we simulated.

Modern approaches in modeling of mobile radio systems propagation environment

Abstract: In this article a review of popular propagation models for wireless communication channels is given. Macrocell, microcell, and indoor prediction methods are considered separately. Advantages and disadvantages of these models are discussed. Also, some practical improvements of the existing models as well as some new models are given.

Mobile phone with interactive printer

Abstract: A mobile telephone (1) may act as a base station for a machine readable code sensor pen (62) to enable connection of the pen (62) with a computer system. The telephone (1) may also include a sensor (80) for sensing the machine readable code and/or a printer (12), for mobile printing of coded substrates.

Base-station-assisted terminal-to-terminal connection setup

Abstract: A system and method for establishing ad hoc communication sessions between remote communication terminals is disclosed. A base station transmits a beacon signal including information about the identity and system clock of the base station. Remote terminals within range lock to the base station, synchronizing their system clocks with the base station's clock and setting their hop sequence and hop sequence phase based on information in the beacon signal. To establish an ad hoc communication session, a master terminal first establishes a link to the base station, which establishes a link to a desired slave terminal. The base terminal exchanges information between remote terminals that enables the master terminal to establish a direct communication session with a slave terminal.

Location privacy feature for wireless mobile stations and method of operation

Abstract: In a wireless mobile station of the type having a position locating system capable of determining the location of the wireless mobile station, there is disclosed control circuitry capable of being selectively set to disable the transmission of information concerning the location of the wireless mobile station. The control circuitry also comprises a directory of telephone numbers of locations authorized to receive information concerning the location of the wireless mobile station. Also disclosed is control circuitry capable of receiving a code that causes the wireless mobile station to transmit information concerning the location of the wireless mobile station. Also disclosed are methods for selectively disabling the transmission of information concerning the location of the wireless mobile station.

Optimum positioning of base stations for cellular radio networks

Abstract: Finding optimum base station locations for a cellular radio network is considered as a mathematical optimization problem. Dependent on the channel assignment policy, the minimization of interferences or the number of blocked channels, respectively, may be more favourable. In this paper, a variety of according analytical optimization problems are introduced. Each is formalized as an integer linear program, and in most cases optimum solutions can be given. Whenever by the complexity of the problem an exact solution is out of reach, simulated annealing is used as an approximate optimization technique. The performance of the different approaches is compared by extensive numerical tests.

Interference suppression in cdma systems

Abstract: A receiver of the present invention addresses the need for improved interference suppression without the number of transmissions by the power control system being increased, and, to this end, provides a receiver for a CDMA communications system which employs interference subspace rejection to tune a substantially null response to interference components from selected signals of other user stations. Preferably, the receiver also tunes a substantially unity response for a propagation channel via which a corresponding user's signal was received. The receiver may be used in a base station or in a user/mobile station.

System and method for re-routing communications based on wireless communication link quality

Abstract: A method for re-routing communications based on link quality includes establishing a first wireless communication link with a mobile station. The first wireless communication link is included in a first communication path used for communications between the mobile station and a destination device. The method also includes monitoring, from the mobile station, the link quality of the first wireless link and determining, at the mobile station, that the link quality of the first communication link has decreased below a low link quality threshold. The method further includes routing, using a router at the mobile station, communications between the mobile station and the destination device to a second communication path that includes a second wireless communication link to the mobile station. The second communication path is selected by the router based on one or more metrics.

Cell planning with capacity expansion in mobile communications: a tabu search approach

Abstract: The cell planning problem with capacity expansion is examined in wireless communications. The problem decides the location and capacity of each new base station to cover expanded and increased traffic demand. The objective is to minimize the cost of new base stations. The coverage by the new and existing base stations is constrained to satisfy a proper portion of traffic demands. The received signal power at the base station also has to meet the receiver sensitivity. The cell planning is formulated as an integer linear programming problem and solved by a tabu search algorithm. In the tabu search intensification by add and drop move is implemented by short-term memory embodied by two tabu lists. Diversification is designed to investigate proper capacities of new base stations and to restart the tabu search from new base station locations. Computational results show that the proposed tabu search is highly effective. A 10% cost reduction is obtained by the diversification strategies. The gap from the optimal solutions is approximately 1/spl sim/5% in problems that can be handled in appropriate time limits. The proposed tabu search also outperforms the parallel genetic algorithm. The cost reduction by the tabu search approaches 10/spl sim/20% in problems: with 2500 traffic demand areas (TDAs) in code division multiple access (CDMA).

Multi-player game system using mobile telephone and game unit

Abstract: A multi-player game system using a mobile telephone and a game unit is disclosed. The present invention links multiple users having game units with mobile phones using a low power radio link. The present invention includes at least one mobile phone having a first transceiver for providing connections to a cellular network and a second transceiver for providing short-haul connectivity, and a plurality of game units for interfacing with a plurality of players, each of the game units having a third transceiver for providing short-haul connectivity, wherein the mobile phones and the game units are linked by the second and third transceivers therein to enable a game to be played on the game units by the plurality of players. In at least one of the mobile phones, the second transceiver is a short range wireless transceiver. At least one mobile phone is used to download a game to the game units and the game units include a group selection interface for choosing players to include in a gaming group. The mobile phones may be linked to a base station, a game server and a network interconnecting the base station and the game server, wherein the game server provides a game across the network and base station to the mobile phones for play on the game units.

Wireless communication system and method and system for detection of position of radio mobile station

Abstract: A method of detecting a position of a radio mobile station in radiocommunications, which is capable of accurately and simply finding the position of the mobile station. At a measuring point the mobile station measures the reception radio strength levels from a plurality of base stations and conveys the measurement results through the base station to a control station. The control station learns, through a neural network, the correlation between the reception radio strength levels and the position of the mobile station on the basis of the measurement results at a plurality of measuring points and the positions of the measuring points. Subsequently, when the mobile station communicates to the control station the reception radio strength levels measured at an arbitrary point, the control station estimates the position of the mobile station, causing those measurement results, on the basis of the correlation obtained through the learning.

Method and apparatus for broadcasting system information in a cellular communications network

Abstract: In a cellular telecommunications system or network, tags are associated with one or more system control parameters. For example, a given tag value may be indicative of particular values for one or more system information parameters. In each cell, a base station (BS) transmits or braodcasts currently valid tag values. System information blocks including the system information parameters themselves (which correspond to particular tag(s)) are also broadcast by base stations. A mobile station receiving a valid tag value from a base station determines whether or not it has to read system information block(s) corresponding to that tag depending upon whether the base station has already stored or cached such block(s) corresponding to the tag value. As will be appreciated by those skilled in the art, different embodiments of the instant invention may result in the mobile station not having to re-read identical system information each time it changes cells, or while moving in the same cell. This may conserve radio resources and reduce battery consumption, thereby improving standby time of the mobile station.

Reservation multiple access

Abstract: A mobile station accesses a base station by randomly selecting a first reverse link common control channel from a set of random access channels The mobile station transmits a request portion of an access probe over the first reverse link common control channel The request portion is subject to collision with other signals The request portion comprises a hash identification which is derived from a uniquely identifying number using a hash function The hash identification quasi-uniquely identifies the mobile station The mobile station receives a channel assignment message from the base station designating the hash identification and a reserved access channel The reserved access channel provides communication with a low probability of contention The mobile station transmits a message portion of the access probe over the reserved access channel

Routing in a multi-station network

Abstract: A method of relaying data between mobile stations in a cellular communications system is provided. The system comprises a number of mobile stations and base stations. Each base station makes synchronization transmissions within its area of covers, which define a broadcast control channel for the transmission of broadcast data from the base station to mobile stations within the area of coverage. The synchronization transmissions are received at mobile stations within the area of coverage, which extracts data defining the broadcast control channel, and at least one calling channel on which mobile stations can transmit probe data to one another. The probe data is used by the mobile stations to obtain connectivity information relating to the availability of other mobile stations. The synchronization transmissions also contain data which is used to define at least one traffic channel which is used by the mobile stations to relay message data between themselves. Effectively, the method of the invention provides a hybrid system which combines conventional cellular technology with opportunistic relaying technology.

Method and arrangement relating to mobile telephone communications network

Abstract: The present invention relates to an arrangement in a mobile communications network, including a first Mobile Station (17), a second Mobile Station, a Base Station device (12), control means (11) to control said Base Station device and means (131, 132, 11, 18, 22) for positioning said first and second Mobile Station, said first Mobile Station being a seeking Mobile Station and said second Mobile Station being a sought Mobile Station The arrangement includes a data storing arrangement (16) for storing position data about said first and second activated mobile stations received from said positioning means (131, 132, 11, 18, 22) and means to process said position data with respect to the position of said first Mobile Station and provide said first Mobile Station with location information of said second Mobile Station

Method and apparatus for maximizing the use of available capacity in a communication system

Abstract: A method and apparatus for maximizing the use of available capacity in a communication system having a base station and a plurality of mobile stations. The forward link in the mobile radio system includes a plurality of traffic streams sent on at least one channel from the base station to the mobile stations. The forward link is subject to a maximum power ceiling. A first output power level associated with simultaneously transmitting a first set of one or more traffic streams from the base station to the mobile stations on the forward link is initially determined. Next, the first output power level is compared to the maximum power ceiling. In response to the comparing step, at least one time frame in the forward link having available capacity for transmitting a portion of at least one further traffic stream is identified. The first set of traffic streams and the portion of the at least one further traffic stream are then transmitted simultaneously during the at least one frame on the forward link.

Method for low-energy adaptive clustering hierarchy

Abstract: A method and network architecture for implementing an energy efficient network. The network includes a plurality of nodes that collect and transmit data that are ultimately routed to a base station. The network nodes form a set of clusters with a single node acting as a cluster-head. The cluster-head advertises for nodes to join its cluster, schedules the collection of data within a cluster, and then transmits the data to the base station. A cluster can intelligently combine data from individual nodes. After a period of operation, the clusters are reformed with a different set of nodes acting as cluster-heads. The network provides an increased system lifetime by balancing the energy use of individual nodes.

Scalable base station architecture

Abstract: A highly flexible base station architecture provides extremely flexible sectorization and capacity expansion capabilities. A base transceiver station (BTS) appliance can be interfaced with similar modules to form a higher capacity, sectorized configuration. Each BTS appliance can function as a standalone cell. In addition, multiple BTS appliances can be connected together to create a multi-sector base station in which the BTS appliances share baseband data, facilitating softer handoff. A backhaul interface module concentrates the backhaul and supports distribution and routing of packets from the network to co-located BTS appliances.

Method and apparatus for determining the location of a remote station in a CDMA communication network

Abstract: An apparatus and method for locating a remote station in a synchronous communications network using the time of arrival of a reference pilot signal at the remote station as a time reference. The time difference of arrival (TDOA) of GPS signals received by the remote station and other signals received from a base station, are measured relative to this reference time. From these measurements, the location of the remote station is determined. The invention treats the location issue as a TDOA problem.

Locating and tracking a user in a wireless network through environmentally profiled data

Abstract: A method for locating a user in a wireless network is disclosed. A mobile computer which seeks to determine its location within a building detects the signal strength of one or more wireless base stations placed at known locations throughout the building. An environmentally profiled table of known locations within the building and the base station signal strength at those locations is searched to find the stored signal strength most similar to the signal strength detected. The location corresponding to the most similar stored signal strength is determined to be the current location of the mobile computer. The table can be derived empirically, by placing a mobile computer at the known locations and measuring the signal strength of the wireless base stations at those locations, or it can be derived mathematically by taking into account a reference signal strength, the distance between the reference point and the known location, and the number of intervening walls between the reference point and the known location. As an alternative, the base stations can measure the signal strength of the mobile computer. In such a case, the table would relate a known position of the mobile computer to the signal strength of the mobile computer as measured by the one or more base stations. Environmental profiling is achieved by comparing several different tables, corresponding to several different environments, and using the table that minimizes the error. Environmental profiling can be applied to tables determined empirically or mathematically.

Generalised sphere decoder for asymmetrical space-time communication architecture

Abstract: A generalised sphere decoding (GSD) algorithm is presented. Its application to the detection of information symbols in a multiantenna cellular system with N antennas at the mobile and M/spl ges/N antennas at the base station is explored. The GSD algorithm has the maximum likelihood (ML) performance for both the uplink and downlink with moderate complexity.

Coexistence techniques in wireless networks

Abstract: Techniques are provided for frequency coordination among two different wireless network protocols, such as the IEEE 802.11 and Bluetooth protocols, operating in proximity with one another. Coordination is accomplished by the use of a first radio transceiver operating in accordance with a first communication protocol (which may be the 802.11 protocol) and using a frequency band (which may be the 2.4 GHz band), a base station connected to a wired network and operating in accordance with the first communication protocol, a second radio transceiver operating in accordance with a second communication protocol (which may be the Bluetooth protocol) and using the frequency band, and a coordinator associated with the base station for, in turn, activating the first radio transceiver, deactivating the first radio transceiver, activating the second radio transceiver, and deactivating the second radio transceiver.

Method and system for handoff between an asynchronous CDMA base station and a synchronous CDMA base station

Abstract: A method and system that enables faster acquisition of the forward link signal of a target base station in a mixed network of synchonous and asynchronous base stations is disclosed. The serving base station transmits in a neighbor list an estimated timing error (417) between the serving base station and a target base station. By utilizing the timing information, a mobile station estimates the relative time offset (408) between forward link signals received from the serving base station and signals received from the target base station. Timing information acquired during handoff enables accurate updating of the estimated timing error (417) subsquently transmitted in the neighbor lists by the base stations.

Group call for a wireless mobile communication device using bluetooth

Abstract: A mobile communication handset (D0) which is configured for communicating by a cellular or PCS or cordless call over a first wireless link (L1) to a base station (12), and is also configured for communicating with one or more other communication devices (D2Dn) over other respective wireless direct device-to-device second links (L2Ln) implemented by the Bluetooth Intercom Profile, is provided with functionality to carry on a group call by appropriately combining speech signals carried by the various links and by the handset The first wireless link (L1) may be a cordless link which is implemented by the Bluetooth Telephony Profile Alternatively, the first link may also be configured as wireless direct device-to-device link, in which case all wireless links involved in the group call are implemented by the Bluetooth Intercom Profile

A multi-user precoding scheme achieving crosstalk cancellation with application to DSL systems

Abstract: This paper describes a precoding scheme capable of achieving crosstalk cancellation in scenarios involving communication from a "base station" to a number of geographically dispersed users. We illustrate that joint processing at the "base station" of the transmitted signals of all users can succeed in removing the otherwise resulting crosstalk. The method employed borrows from the concept of the Tomlinson-Harashima (1971, 1972) precoder which is often used for equalization against intersymbol interference (ISI). One possible application of the proposed technique is in digital subscriber line (DSL) systems, where far end crosstalk (FEXT) poses a severe transmission constraint. Simulation results show that significant improvements can be realized in such scenarios.

RF signal repeater, mobile unit position determination system using the RF signal repeater, and method of communication therefor

Abstract: A RF signal repeater system is added to a wireless communications network which increases user data rates at the periphery of the cellular coverage area by boosting the downlink (base station to mobile user) signal and uplink (mobile user to base station) signal. The RF signal repeater system includes a signal tagging means that adds a unique electronic signature to the repeated signal such that position determination errors due to a non-line of sight propagation path can be corrected. The repeated signal is received and processed with a location measurement unit to determine the time of arrival and to extract the signal tag of the repeated signal. The time of arrival measurement and recovered signal tag are then processed at a mobile location center to determine the true position of the transmitter.

Method for controlling power for a communications system having multiple traffic channels per subscriber

Abstract: A power control method of the invention may be applied to downlink power control, uplink power control, or both to support different quality of service levels for multiple channels per a mobile station. The power control method transmits control data between a base station and a multi-channel mobile station on a single communications channel or sub-channel to minimize or reduce overhead traffic from the control data.

Single station communications localization system

Abstract: The present invention combines the measured characteristics of a radio signal in a communications environment with collateral information to produce an accurate and economical way to locate a mobile transmitter station, such as a mobile telephone, in a cellular telephone network.

Wireless communication system with base station beam sweeping

Abstract: A method and apparatus for wireless communications wherein a base station (102) transmits a signal to sending data to a subscriber station (108) through a signal beam (110) that sweeps through the coverage area of the base station (102). User data addressed to the subscriber station (108) is buffered until the signal beam angle of the signal (110) beam allows efficient transmission. The base station (102) may alter the beam sweep speed or the shape of the beam's radiation pattern (106) over time to maximize system efficiency and capacity.

Method and apparatus for variable and fixed forward link rate control in a mobile radio communication system

Abstract: A method and apparatus for controlling a data rate associated with the transmission of information from a base station (100) to a mobile station (300) in a mobile radio communication system. The mobile station (300) alternately receives information from a basestation (100) either in a variable rate mode or a fixed rate mode. The transmission rate from a base station (600) in the variable rate mode varies between successive data transmit intervals, and the transmission rate from a base station in the fixed rate mode remains fixed between successive data transmit intervals. Data is transmitted from a first base station (400) to the mobile station in the variable rate mode until the first base station is unable to receive the variable data rate control information from the mobile station. When the first base station (400) is unable to receive the variable data rate control information from the mobile station (300), the mobile station (300) attempts to remain in the variable rate mode by searching for a second base station that will support data transmissions to the mobile station (300) in the variable rate mode and, if the mobile station (300) is able to locate the second base station that will support data transmissions to the mobile station in the variable rate mode, then the second base station transmits data to the mobile station in the variable rate mode and transmissions from the first base station to the mobile station (300) in the variable rate mode terminate. If the mobile station is unable to locate the second base station that will support data transmissions to the mobile station in the variable rate mode, data is transmitted to the mobile station (300) from either the first base station (400) or a different base station in the fixed rate mode.