Showing papers on "Base station published in 1999"

Distributed quality-of-service routing in ad hoc networks

Abstract: In an ad hoc network, all communication is done over wireless media, typically by radio through the air, without the help of wired base stations. Since direct communication is allowed only between adjacent nodes, distant nodes communicate over multiple hops. The quality-of-service (QoS) routing in an ad hoc network is difficult because the network topology may change constantly, and the available state information for routing is inherently imprecise. In this paper, we propose a distributed QoS routing scheme that selects a network path with sufficient resources to satisfy a certain delay (or bandwidth) requirement in a dynamic multihop mobile environment. The proposed algorithms work with imprecise state information. Multiple paths are searched in parallel to find the most qualified one. Fault-tolerance techniques are brought in for the maintenance of the routing paths when the nodes move, join, or leave the network. Our algorithms consider not only the QoS requirement, but also the cost optimality of the routing path to improve the overall network performance. Extensive simulations show that high call admission ratio and low-cost paths are achieved with modest routing overhead. The algorithms can tolerate a high degree of information imprecision.

Fair scheduling in wireless packet networks

Abstract: Fair scheduling of delay and rate-sensitive packet flows over a wireless channel is not addressed effectively by most contemporary wireline fair-scheduling algorithms because of two unique characteristics of wireless media: (1) bursty channel errors and (2) location-dependent channel capacity and errors. Besides, in packet cellular networks, the base station typically performs the task of packet scheduling for both downlink and uplink flows in a cell; however, a base station has only a limited knowledge of the arrival processes of uplink flows. We propose a new model for wireless fair-scheduling based on an adaptation of fluid fair queueing (FFQ) to handle location-dependent error bursts. We describe an ideal wireless fair-scheduling algorithm which provides a packetized implementation of the fluid mode, while assuming full knowledge of the current channel conditions. For this algorithm, we derive the worst-case throughput and delay bounds. Finally, we describe a practical wireless scheduling algorithm which approximates the ideal algorithm. Through simulations, we show that the algorithm achieves the desirable properties identified in the wireless FFQ model.

Wireless location using multiple location estimators

Abstract: A location system is disclosed for commercial wireless telecommunication infrastructures. The system is an end-to-end solution having one or more location centers for outputting requested locations of commercially available handsets or mobile stations (MS) based on, e.g., CDMA, AMPS, NAMPS or TDMA communication standards, for processing both local MS location requests and more global MS location requests via, e.g., Internet communication between a distributed network of location centers. The system uses a plurality of MS locating technologies including those based on: (1) two-way TOA and TDOA; (2) pattern recognition; (3) distributed antenna provisioning; (5) GPS signals, (6) angle of arrival, (7) super resolution enhancements, and (8) supplemental information from various types of very low cost non-infrastructure base stations for communicating via a typical commercial wireless base station infrastructure or a public telephone switching network. Accordingly, the traditional MS location difficulties, such as multipath, poor location accuracy and poor coverage are alleviated via such technologies in combination with strategies for: (a) automatically adapting and calibrating system performance according to environmental and geographical changes; (b) automatically capturing location signal data for continual enhancement of a self-maintaining historical data base retaining predictive location signal data; (c) evaluating MS locations according to both heuristics and constraints related to, e.g., terrain, MS velocity and MS path extrapolation from tracking and (d) adjusting likely MS locations adaptively and statistically so that the system becomes progressively more comprehensive and accurate. Further, the system can be modularly configured for use in location signing environments ranging from urban, dense urban, suburban, rural, mountain to low traffic or isolated roadways. Accordingly, the system is useful for 911 emergency calls, tracking, routing, people and animal location including applications for confinement to and exclusion from certain areas.

IP-flow classification in a wireless point to multi-point (PTMP) transmission system

Abstract: An IP flow classification system is used in a wireless telecommunications system. The IP flow classification system groups IP flows in a packet-centric wireless point to multi-point telecommunications system. The classification system includes: a wireless base station coupled to a first data network; one or more host workstations coupled to the first data network; one or more subscriber customer premise equipment (CPE) stations in wireless communication with the wireless base station over a shared bandwidth using a packet-centric protocol; and one or more subscriber workstations coupled to each of the subscriber CPE stations over a second network; a resource allocation device optimizes end-user quality of service (QoS) and allocates shared bandwidth among the subscriber CPE stations; an analyzing and scheduling device analyzes and schedules internet protocol (IP) flow over the shared wireless bandwidth. The analyzing device includes the above IP flow classifier that classifies the IP flow. The classifier can include a device for associating a packet of an existing IP flow with the IP flow. The classifier can include a QoS grouping device that groups a packet of a new IP flow into a QoS class grouping. The QoS grouping device can include a determining device that determines and takes into account QoS class groupings for the IP flow. The QoS grouping device can include an optional differentiated services (Diff Serv) device that takes into account an optional Diff Servs field priority marking for the IP flow.

Area spectral efficiency of cellular mobile radio systems

Abstract: A general analytical framework quantifying the spectral efficiency of cellular systems with variable-rate transmission is introduced. This efficiency, the area spectral efficiency, defines the sum of the maximum average data rates per unit bandwidth per unit area supported by a cell's base station. Expressions for this efficiency as a function of the reuse distance for the worst and best case interference configurations are derived. Moreover, Monte Carlo simulations are developed to estimate the value of this efficiency for average interference conditions. Both fully loaded and partially loaded cellular systems are investigated. The effect of random user location is taken into account, and the impact of lognormal shadowing and Nakagami (1960) multipath fading is also studied.

Method for effectively implementing a wireless television system

Abstract: A method for effectively implementing a wireless television system comprises a wireless base station that processes and combines various program sources to produce a processed stream. A transmitter then responsively transmits the processed stream as a broadcast output stream to various portable wireless display devices for flexible viewing at variable remote locations.

Optimum beamforming using transmit antenna arrays

Abstract: Transmit beamforming is a powerful means of increasing capacity in systems in which the transmitter is equipped with an antenna array, especially in systems in which receive beamforming is not available, as is typical in the base-to-mobile downlink in a cellular communication system. In this paper, the problem of transmit beamforming is formulated as one of minimizing the power radiated by the base station, subject to satisfying quality of service requirements at the mobiles. For a single cell system, a global minimum is shown to exist, and an iterative algorithm that converges to it is provided. The solution extends to accommodate receive beamforming at the mobiles. It also extends to provide a mechanism for space-time transmit filtering, which exploits the differences between the temporal as well as the spatial channels between the base station and different mobiles. Finally, a system with multiple source-destination pairs (e.g., in an ad hoc network) is considered. An iterative algorithm that outputs a convergent sequence of feasible points with monotonically decreasing costs is provided for this case.

System and method for determining the position of a wireless cdma transceiver

Abstract: An apparatus and method to determine a position of a mobile wireless transceiver. The invention merges GPS position location and wireless communication technologies to achieve a precise position location in dense urban and other environments when line-of-sight to the satellites is somewhat obscured. The inventive apparatus and method use signals from only two GPS satellites (60, 70, 80, 90) and the serving terrestrial base station. In a most general sense, the inventive method includes the steps of receiving at a base station (10) a first signal transmitted from a first GPS satellite and a second signal transmitted from a second GPS satellite. The mobile's transmitter (200) and receiver (100) are adapted to receive these GPS signals as well and transmit a third signal to the base station in response thereto. The base station (10) receives the third signal and uses it to calculate the position of the wireless unit (20).

Method and apparatus for power saving in a mobile terminal with established connections

Abstract: Power consumption of a mobile terminal is reduced by providing a system wherein a base station specifies a time period, at the end of which a mobile terminal that is hibernating in a power-saving mode will listen for paging messages from the base station. If no paging messages are present, then the mobile terminal continues hibernating, thus conserving battery power by not communicating with the base station. Either the base station or the mobile terminal can initiate a process to transfer the mobile terminal from an awake mode to a hibernating mode. In accordance with another embodiment of the invention for use in systems that require frequent connectivity testing, an agent can be provided within the base station to answer connectivity test inquiries on behalf of the mobile terminal. The mobile terminal can communicate periodically with the base station to update information that the agent uses to respond to the test inquiries.

Cellular communication system with common channel soft handoff and associated method

Abstract: A cellular communications system comprising: a mobile unit which designates an active set of base stations; a base station; and a base station controller which puts the base stations in the active set in common channel soft handoff.

Location tracking of mobiles in cellular radio networks

Abstract: Some useful services in cellular radio networks and also a class of handover algorithms require knowledge of the present position and velocity of mobiles. This paper deals with a method to track mobiles by on-line monitoring of field strength data of surrounding base stations at successive time points. Such data is available in present global system for mobile communication (GSM) systems each 0.48 s and also in code-division multiple-access (CDMA) systems for transmission control. Because of strong random fluctuations of the signals, appropriate smoothing is the key point of the procedure. We develop a locally linear prediction model of successive positions as a basis for Kalman filtering. This approach turns out to be extremely successful, achieving average mislocations of 70 m in simulated test runs. Further improvement is possible by using external geographical information.

Wireless push-to-talk internet broadcast

Abstract: A wireless telephone (302) digitizes the voice of the user in response to the depression of a push-to-talk button (110), either physical or virtual. It sends the digitized voice, in data mode, to a base station (308). The base station places the data, through the Internet, or an Intranet or Extranet, on a server (312). Other wireless phones (304-306) recover the data from the server through the same (308) or different (310) base station, through the Internet, Intranet, or Extranet, and convert the data back to digitized voice. The base stations transmit the digitized voice to other wireless telephones (306), which convert them back to voice in response to the recognition of voice frames on the data channel by the CODEC manager software. Networked computers (314) may be configured to emulate a combined base station and wireless telephone. The server can dynamically designate any wireless telephone (or landline emulation) as the broadcaster, and can dynamically configure any set of telephones/emulations as the receivers of the broadcast.

Location system combining ranging measurements from GPS and cellular networks

Abstract: Methods and arrangements are provided for locating a mobile terminal (38) within a mobile telecommunications system. In certain embodiments, GPS ranging signals (14) and cellular base station (20) transmitted downlink signals are received by a mobile terminal, which is configured to determine its current location using a combination of these two types of ranging signals. In certain other embodiments, GPS ranging signals (14) are received by the mobile terminal (38), which is also configured to transmit uplink signals to cellular base stations (20). The current location of the mobile station is determined by fusing measured data from each of these different ranging signal transmissions. By combining the available resources of satellite and terrestrial (20) locating processes, the potential for locating a mobile terminal (38) is significantly increased.

Interactive voice, wireless game system using predictive command input

Abstract: A system and a method for providing an interface to and customizing an interactive application for one or more players is provided. The interactive game of the presently preferred embodiment is played in a wireless environment using a mobile station as a user interface with commands entered via a keyboard or via voice. The game is tracked and controlled using a game center and a game server, which is typically at a location remote from the mobile station. Communication between the game server and the mobile station is typically performed using a base station connected to a telecommunications network. The game server executes a software application, which runs a game center. Individual games are managed within the context of this application.

Two phase local mobility scheme for wireless access to packet based networks

Abstract: Local mobility within a subnet is supported by classifying wireless base stations, and the routers used to forward packets to those base stations, within defined domains. Domains are defined to incorporate a subnet having a plurality of base stations. Base stations are used by mobile devices to attach to the wired portion of a packet-based network, such as the Internet, and exchange packets thereover with a correspondent node. Packets sent from the correspondent node to the mobile device have a packet destination address corresponding to the mobile device. The mobile device retains this address for the duration of time it is powered up and attached to the Internet via any base station within a given domain. Host-based routing is utilized to update routing table entries corresponding to the mobile device at routers incorporated within a single domain. The routing table entries are established and updated via path setup schemes to convey packets destined for the mobile device along the proper established path through the domain routers and base stations, regardless of the domain base station through which the mobile device is attached. Path setup schemes utilize power up, refresh, and handoff path setup messages to maintain the proper relationship between router interfaces and packet addresses for routing table entries.

Dynamic resource allocation schemes during handoff for mobile multimedia wireless networks

Abstract: User mobility management is one of the important components of mobile multimedia systems. In a cell-based network, a mobile should be able to seamlessly obtain transmission resources after handoff to a new base station. This is essential for both service continuity and quality of service assurance. In this paper, we present strategies for accommodating continuous service to mobile users through estimating resource requirements of potential handoff connections. A diverse mix of heterogeneous traffic with diverse resource requirements is considered. The investigate static and dynamic resource allocation schemes. The dynamic scheme probabilistically estimates the potential number of connections that will be handed off from neighboring cells, for each class of traffic. The performance of these strategies in terms of connection blocking probabilities for handoff and local new connection requests are evaluated. The performance is also compared to a scheme previously proposed by Yu and Leung (see IEEE J. Select. Areas Commun., vol.15, p.1208-25, 1997). The results indicate that using dynamic estimation and allocation, we can significantly reduce the dropping probability for handoff connections.

Adaptive power control in a radio communications systems

Abstract: Delays on a common radio communications channel employed by plural mobile stations to communicate with a base station located in a corresponding geographical cell area are minimized by adapting transmission power based on traffic conditions. For lower traffic loads, a higher transmission power is permitted. For higher traffic loads, a lower power level is set. A transmit power level is determined using a desired signal ratio, such as a target CIR, a transmission path loss over the radio communications channel, and an interference value. One or more adaptive power parameters are also employed in that determination to adapt the open loop power control based on one or more current communications conditions and/or characteristics of the mobile station. For example, an adaptive power parameter may be a function of a current interference in a base station cell either alone or in combination with a current interference in one or more neighboring cells. The adaptive power parameter may also account for a type of data packet connection to be employed between the mobile station and the base station after random access, a mobile station's subscription, a current temperature of the mobile station, a current base station used by the mobile station, a current estimated path loss between the mobile station and base station, and/or other factors.

Radio communication device and method of controlling transmission rate

Abstract: The communication terminal apparatus measures reception quality and reports the measurement result to the base station apparatus, and the base station apparatus switches the transmission rate based on the reported result of the reception quality. In this way, the transmission rate is switched starting at the point in time at which the reception quality of the communication terminal apparatus deteriorates. Furthermore, the transmission rate is switched so that the amount of interference with others is within the allowable range according to the channel condition between the communication terminal apparatus and base station apparatus.

Method and system for aiding GPS receivers via a cellular or PCS network

Abstract: In accordance with the invention, there is disclosed a system for determining location of a mobile station. The mobile station includes a transceiver operating in a wireless network and a GPS receiver. The system includes a wireless network control system including GPS receivers for obtaining ephemeris data. The control system develops assistance information from the ephemeris data and transmits the assistance information to the mobile station via the wireless network. The assistance information represents range at a fixed location in the wireless network in proximity to the mobile station at a select time, and derivatives of the range, relative to plural select satellites in the GPS. The mobile station utilizes received assistance information for searching the composite received signals from the plural select satellites in the GPS to measure a code phase for plural ones of the select satellites in the GPS and returning the measured code phases to the wireless network control system via the wireless network. The wireless network control system computes location of the mobile station in the wireless network utilizing a fixed location and the measured code phases.

Method and system for restricting the operation of a radio device within a certain area

Abstract: A cellular radio system comprises a multitude of base stations (101-106, 201-204, 211-212, 501-504) for offering a radio interface to mobile terminals (205, 215, 508). The radio interface is used for communicating general information to the mobile terminals and arranging for dedicated communication between a certain mobile terminal and the cellular radio system. For imposing restrictions to the operation of the mobile terminals on at least one isolated, geographically defined restricted area (107, 108, 200, 213) the system comprises a certain first base station arranged to transmit, similary to said general information, information about the nature of the restrictions applicable on said area to the mobile stations.

IP-flow characterization in a wireless point to multi-point (PTMP) transmission system

Abstract: The present invention is directed to a packet-centric wireless point to multi-point telecommunications system, including: a wireless base station coupled to a first data network; one or more host workstations coupled to the first data network; one or more subscriber customer premise equipment (CPE) stations in wireless communication with the wireless base station over a shared bandwidth using a packet-centric protocol; and one or more subscriber workstations coupled to each of the subscriber CPE stations over a second network; a resource allocation device optimizing end-user quality of service (QoS) and allocating shared bandwidth among the subscriber CPE stations; a device for analyzing and scheduling an internet protocol (IP) flow over the shared wireless bandwidth. The analyzing device includes a characterizing device for characterizing the IP flow. The characterizing device can include a device for determining whether a packet is older than a threshold age. The age determining device can include a device for analyzing a time to live (TTL) packet header field for determining the age of the packet, or a device for anticipating application IP flow discards based on the age of the packet. The characterizing device can include a device for determining a QoS requirement for the IP flow if the IP flow is a new IP flow. The characterizing device scan include a device for determining a subscriber CPE identification for a subscriber CPE station associated with the IP flow if the IP flow is a new IP flow.

Gps location for mobile phones using the internet

Abstract: A position locating system and method are provided for determining a geographic location of a portable remote unit. The locating system includes a communications system having at least one base station and a system controller. The base station bi-directionally couples the remote unit to the system controller through wireless links. The locating system also includes a server coupled to the system controller by a communication infrastructure external to the communications system. The server includes a data store which contains satellite positioning information. In response to a message from the remote unit, the server provides satellite information to the system controller over the communication infrastructure such that the provided satellite information is passed to the remote unit by the base station. The provided satellite information includes information to aid in acquiring a predetermined number of satellites within a satellite positioning system. The acquired satellites provide coded signals for determining the geographic location of the remote unit. In one embodiment, the data communication system is a cellular telephone network and the communication infrastructure is the Internet. The Internet is coupled to the cellular telephone network through a public switched telephone network (PSTN).

Method for the recognition and operation of virtual private networks (VPNs) over a wireless point to multi-point (PtMP) transmission system

Abstract: A packet-centric wireless point to multi-point telecommunications system includes a wireless base station coupled to a first data network; one or more host workstations coupled to the first data network; one or more subscriber customer premise equipment (CPE) stations in wireless communication with the wireless base station over a shared wireless bandwidth using a packet-centric protocol; and one or more subscriber workstations coupled to each of the subscriber CPE stations over a second network; resource allocator optimizing end-user quality of service (QoS) and allocating shared bandwidth among the subscriber CPE stations; a scheduler to schedule an internet protocol (IP) flow over the shared wireless bandwidth. The scheduler includes a prioritizer for prioritizing the IP flow based on priorities of a virtual private network (VPN). The system can include an analyzer for analyzing the virtual private network (VPN) priorities for the IP flow, or for prioritizing all VPN IP flows. The system can include a prioritizer to prioritize the IP flow based on one or more subscriber-defined parameters. In the system, the VPN can include a directory enabled networking (DEN) table management scheme. The VPN can be implemented using a point-to-point tunneling protocol (PPTP). Also included is a method for accomplishing the above.

Communication system with fast control traffic

Abstract: A method and system for conducting rapid control traffic in a time division multiple access (TDMA) communication system comprises a base station communicating with a plurality of user stations in assigned time slots of a time frame. For bearer traffic, time slots are assigned to particular user stations for an extended duration. In unassigned time slots, the base station transmits a general polling message indicating availability of the time slot. A user station desiring to hand off communication from one base station to another uses multiple available time slots at the target base station for exchanging control traffic messages with the target base station. The next available time slot is indicated by a slot pointer in the header of each general polling message to facilitate rapid exchange of control traffic messages. During handover, the user station may establish a new link with the target base station before relinquishing the existing communication link with the old base station.

Power control device and method for controlling a reverse link common channel in a CDMA communication system

Abstract: A common power control channel transmission device for a base station in a CDMA communication system is provided having a selector for receiving power control commands to be transmitted to multiple subscribers and multiplexing the received power control commands; and a spreading modulator for spreading an output of the selector by multiplying the output of the selector by a spreading sequence. The common power control channel transmission device can be used to control power of a reverse link common channel. For the power control of the reverse link common channel, the base station receives a signal from a mobile station via the reverse link common channel, and transmits to the mobile station a power control command for controlling a transmission power of the reverse link common channel according to a measured strength of the received signal.

Device and method for gating transmission in a cdma mobile communication system

Abstract: A method for determining a gating rate in a base station for a CDMA communication system is disclosed. The method comprises transmitting information for assigning a dedicated control channel and a traffic channel to a mobile station, when a call is generated; after call setup, transmitting a message requesting mobile station's capability information to the mobile station; receiving the capability information including gating availability information of a reverse pilot signal and information about at least one gating rate, transmitted from the mobile station in reply to the request message; and determining a gating rate according to the capability information, transmitting information about the determined gating rate to the mobile station, and transitioning to an active sate. The mobile station's capability information includes information about gating availability and at least one gating rate, when gating is available.

Method and apparatus for increasing the sensitivity of a global positioning satellite receiver

Abstract: Method and apparatus providing enhanced sensitivity for GPS receivers (400, 500, 600, 700) by allowing coherent integration of a correlation over several code periods of a GPS signal in one embodiment, and by performing a time to frequency domain conversion to the output from a correlation processor (507) in a second embodiment. In the case in which coherent integration is performed over several code periods, advantage is taken of the fact that CDMA cellular telephone base stations transmit information that allows the receiver to determine GPS time before beginning a GPS signal acquisition process. The integration can be expanded to include code periods from more than one bit period, if the GPS receiver (400, 500, 600, 700) takes advantage of the fact that known bit patterns are transmitted at particular times within the transmission from a GPS satellite. If no base station is within range, then the output from a correlator (507) that integrates a correlation over one code period is used to generate values that are input to a discrete time domain to frequency domain transform processor (511). The output from the transform processor (511) will indicate the presence of a signal from a particular satellite and the offset between locally generated signal and the received GPS signal.

Software radio issues in cellular base stations

Abstract: The use of the "software radio" concept in cellular applications is a topic of widespread interest. Two key issues in the implementation of software radios are the development of optimal receivers that require the minimum number of bits in the wide-band analog-to-digital converter (ADC) and efficient channelizers that extract individual channels from the digitized wide-band signal. In this paper, both of these issues are studied in detail for cellular base stations. A computationally efficient wide-band channelizer is presented. This channelizer is closely related to the discrete Fourier transform filter bank used in transmultiplexers. It is shown that the complexity of the proposed channelizer is significantly less (2-50/spl times/) than the complexity of conventional channelizers. An optimal receiver that explicitly takes into account the effect of the quantization noise of the wide-band ADC is also derived. The analysis of the ADC noise provides guidelines for specifying wide-band ADC for use in cellular applications. The development of the channelizer and the optimal receiver yield important insights into the implementation of cellular software radios. All of the key results of this paper are applied to a detailed example based on the Digital Advanced Mobile Phone System (D-AMPS, IS-54/IS-136) cellular standard. The bit-error rate (BER) performance simulations of a D-AMPS wide band receiver is presented as a part of this example.

Method and apparatus for providing wireless communication system synchronization

Abstract: When insufficient traffic is present in the network to maintain synchronization in this manner, other methods must be used. One approach involves making direct measurements of the timing between base stations (602, 604). This is accomplished in one of two ways. The base may interrupt its transmissions on all sectors for a short interval during which it determines the time of arrival of signals from other base stations (602, 604). Given knowledge of the other base station locations, time errors relative to all other base stations (602, 604) may be derived. Alternatively, the base may send a short signal at high power in the mobile transmit band. This time-of-arrival of this signal is measured by the surrounding base stations and the time errors between pairs of base stations are computed. In some cases, a base station (602, 604) may be isolated sufficiently from all other base stations in the network such that direct base-to-base measurement is not viable. In this case, a fixed mobile (606) is placed at a location in the handoff region between the isolated cell and another cell in the network. The fixed mobile (606) either performs measurements of base station pilots on command of the base and reports the timing information, or sends a burst transmission at a specified time and power level to be measured by the base stations.