Showing papers by "Qualcomm published in 1996"

Client-server-based remote locator device

Abstract: A user accesses a server using a client. The client provides an identification code which serves to uniquely identify a remote sensor. The remote sensor is capable of providing information related to its position. The server interrogates the remote sensor and, in response, the remote sensor transmits positioning data to the server where it is analyzed to derive the location of the remote sensor. The location so determined is transmitted from the server to the client and is displayed at the client so that the user can identify the location of the remote sensor. The client and the server may be connected to a computer network and the client may use a web browser to interrogate the server. The remote sensor may be a SNAPSHOT GPS receiver or other GPS receiver or positioning device. The user display may be a simple position report, e.g., latitude and longitude, or a graphical report which provides an indication of the remote sensor's location superimposed on a map or other reference.

Wireless remote telemetry system

Abstract: A wireless remote telemetry system which uses low-cost remote communication devices operating on existing wireless communication systems in order to provide real-time reading and control of remote devices. In an embodiment applicable to utility service, consumption of electrical power among a population of customers is measured by a utility metering system having a wireless communication capability. The metering system comprises a remote metering unit which communicates with a central controller over existing wireless communication systems, such as cellular base stations, using existing communication standards. The remote metering unit transmits various messages over a shared random access channel to a central controller. The central controller transmits messages to the remote metering unit over a paging channel. The remote metering unit may operate in a half-duplex mode only. Furthermore, the remote metering unit may provide a gateway to advanced consumer services at the remote location.

Random access communications channel for data services

Abstract: In a digital communication system for communicating digital information (100), the digital communication system having a forward link (120) and a reverse link (130), a system and method for communicating a data packet. The system comprises a communicating transceiver (202), from among a number of digital transceivers (102), for sending the data packet on a random access channel (208) over the reverse link and for receiving the digital information from the forward link. The system also comprises a base station (108) for receiving the data packet on the random access channel (208) from the reverse link (130) and for sending the digital information over the forward link (120). The digital transceivers (102) share the random access channel (208). The digital transceivers (102) have a bandwidth demand. The system (100) may also include a dedicated channel (214) for communicating the data packet between the communicating transceiver (202) and the base station (108) and a processor (212) for switching from the random access channel (208) to the dedicated channel (214) when the bandwidth demand exceeds a first threshold, and for switching from the dedicated channel (214) to the random access channel (208) when the bandwidth demand drops below a second threshold. The system is well suited for use in CDMA applications.

Concentrated subscriber wireless remote telemetry system

Abstract: A concentrated subscriber wireless remote telemetry system which uses low-cost remote communication devices operating on existing wireless communication systems in order to provide real-time reading and control of remote devices. The metering system comprises at least one powerline remote metering device which collects and forwards telemetry data to an associated wireless remote telemetry device. The wireless remote telemetry device relays the telemetry data to a central controller over existing wireless communication systems, such as cellular base stations, using existing communication standards. The wireless remote metering device transmits various messages over a shared random access channel to the central controller. The central controller transmits messages to the wireless remote metering unit over a paging channel. The wireless remote metering unit may operate in a half-duplex mode only. Furthermore, the wireless remote metering unit may provide a gateway to advanced consumer services at the remote location.

Wireless telecommunications system utilizing CDMA radio frequency signal modulation in conjunction with the GSM A-interface telecommunications network protocol

Abstract: A method and apparatus for operating a wireless telecommunication system utilizing code division multiple access (CDMA) over-the-air with a Global System for Mobile (GSM) communications A-interface based network is described. A CDMA radio frequency (RF) signal interface provides a bi-directional interface to a subscriber unit (50), and a Global System for Mobile (GSM) communications A-interface SS7 transport provides a bi-directional interface with GSM mobile services switching center (MSC) (52). Additionally, a transparent message transport (44) is provided over which signaling messages defined in the GSM A-interface protocol are exchanged between the GSM MSC (52) and a subscriber unit (50).

Method and apparatus for using full spectrum transmitted power in a spread spectrum communication system for tracking individual recipient phase time and energy

Abstract: Method and apparatus for tracking the frequency and phase of signals in spread spectrum communication systems that makes more efficient use of available carrier frequency and phase information by utilizing a substantial portion or all of the energy occupying the frequency spectrum of a received carrier signal, including energy from communication signals intended for other system users. Multiple spread spectrum communication signals (182) are input in parallel to data receivers (126 A'-N') where they are despread using preselected despreading codes at an adjustable phase angle and decoded over multiple orthogonal codes active within the communication system. Multiple decoded signals are then combined (188) to form a single phase detection signal which is used by at least one tracking loop (184) to track frequency and phase of the carrier signal for the received communication signals. The tracking loop (184) generates a timing signal which is used to adjust the phase angle (186) used during despreading. In further embodiments, the communication signals are despread using appropriate PN codes and separated into in-phase (I) and quadrature channels (Q) (214) where data symbols are processed by fast Hadamard transformers (218, 220) to generate corresponding data bits. The data is formed into pairwise products between the channels (224), and summed over multiple or all active subscriber orthogonal codes (226). This sum indicates a degree to which the estimated phase differs from the actual phase of received communication signals and is used to adjust the phase of application for the PN codes (230).

Position and time-at-position logging system

Abstract: One embodiment of a position and time-at-position logging apparatus includes a GPS receiver, a microprocessor, memory, a keypad and a data port. The apparatus receives GPS signals and determines therefrom position and time-at-position information of the apparatus, and logs the information in memory in response to a key depression in a manual mode of operation, or in response to a data capture signal in an automatic mode of operation. The data port may be connected to an input device for generating the data capture signal, an output device for data reporting, or to a computer operable to program an operational mode of the apparatus or download a number of sets of information for processing by report generating software resident therein. The apparatus may optionally include a radio transceiver for exchanging data and/or programming information with a remote source, and may further include a vehicle data port for receiving operational data in accordance with various vehicle/engine operating parameters.

Method and apparatus for monitoring parameters of vehicle electronic control units

Abstract: A system for monitoring and the adjustment of control unit parameter settings of vehicle electronic control units (44, 45). The monitoring system may be implemented in a vehicle (12, 14) in which are incorporated one or more electronic control units (44, 45) for regulating one or more operational parameters of the vehicle (12, 14) in accordance with corresponding control unit parameter settings. In an exemplary implementation the vehicle (12, 14) is equipped with a mobile communications terminal, MCT (38), which receives from a base station (18) a list of operational parameters to be monitored. Each of the electronic control units (44, 45), as well as a memory unit (62), are connected to an internal data link (40) of the vehicle. When a parameter value within the memory unit (62) corresponding to a given electronic control unit (44, 45) is changed, a message is provided to the base station (18) specifying the value currently registered by the particular electronic control unit (44, 45). The currently registered value is then compared to an expected parameter value, and an error message is generated if disagreement exists therebetween. The system also allows vehicle electronic control unit parameter settings to be adjusted from a remote location such as a base station (18).

Method/apparatus for an accelerated response to resource allocation requests in a CDMA push-to-talk system using a CDMA interconnect subsystem to route calls

Abstract: In a push-to-talk dispatch system, a method and apparatus for providing an accelerated response to a push-to-talk origination message. A first base station allocates a first set of equipment to support a push-to-talk connection. A first system controller allocates a second set of equipment to support the push-to-talk connection. Upon receipt of a push-to-talk origination message from a first remote unit, the first base station transmits an immediate response to the first remote unit, instructing it to communicate through the first set of equipment and the second set of allocated equipment.

Portable communication device and accessory system

Abstract: A portable communications device and accessory system which enables both voice and control commands to be communicated between a portable communication device and external accessories over a single flexible digital interface. When the portable communication device is interfaced to external accessories, such as a power booster and hands-free kit, a microprocessor configures the serial communications bus to pass both the digital voice data and digital control commands to and from the external power booster and the hands-free kit. The external hands-free kit contains its own auxiliary CODEC for encoding analog voice signals and decoding the digital voice data. When the portable communication device is not interfaced with external accessories, the microprocessor configures the serial communication bus to pass the digital voice data to and from an internal CODEC for use with the portable device's own microphone and speaker.

Dual-mode communications processor

Abstract: A dual-mode communications processor disposed to be incorporated within a dual-mode communications device is disclosed herein. The dual-mode communications processor comprises a dual-mode voiceband signal processor having an input port for receiving digitized data. Within the dual-mode voiceband signal processor, first and second signal processing operations are performed upon the digitized data received during operation in first and second modes, respectively. These separate signal processing operations may advantageously be performed using common circuit elements within the dual-mode voiceband signal processor. In an exemplary embodiment the first signal processing operation is performed in accordance with a predefined vocoding algorithm, while the second signal processing operation involves the filtering of the digitized data as prescribed by FM cellular telephone standards. The dual-mode communications processor further includes a digital modulation modem coupled to the dual-mode voiceband signal processor. The digital modulation modem generates digital modulation data using the digitized data processed by the dual-mode voiceband signal processor during operation in the first mode. An FM modulator, also coupled to the dual-mode voiceband signal processor, generates FM modulation data using the digitized data processed by the dual-mode voiceband signal processor during operation in the second mode. A controller is provided for selecting between operation in the first and second modes. A dual-mode port allows the digitized data to be transferred to and from a dual-mode interface buffer over a common signal path during operation in both the first and second modes.

Effects of nonlinear distortion on CDMA communication systems

Abstract: We report a rigorous approach to analyze the effects of nonlinear distortion on code division multiple access (CDMA) wireless communication systems based on time-domain analysis and band-pass nonlinearity theory. Given AM-AM and AM-PM characteristics of a nonlinear device, this technique is capable of predicting adjacent channel power rejection (ACPR), noise power ratio (NPR), two-tone intermodulation products, CDMA waveform quality, and baseband signal vector constellation at the output of the nonlinear device. To demonstrate and verify the capability of this technique, an L-band power amplifier was designed, built, tested with CDMA waveforms, and compared with the simulated results. Excellent agreement between the measured and predicted results has been achieved.

Method and apparatus for access regulation and system protection of a dispatch system

Abstract: A method and apparatus to provide access to a dispatch system is disclosed. A communications manager (40) grants an exclusive system talker privilege to one remote unit (10) in the system at a time. After a remote unit (10) requests and is designated as the exclusive system talker, no other remote unit (20, 22) may transmit for a first pre-determined amount of time. After the first pre-determined time has elapsed, any other remote unit (20, 22) may request the exclusive system talker privilege and become the exclusive system talker. The exclusive system talker privilege is revoked by the communications manager (40) to any remote unit who retains the exclusive system talker privilege for more than a second pre-determined amount of time. The exclusive system talker privilege is also revoked upon the release of a push-to-talk button on a remote unit (10). Furthermore, a base station (44) in communication with a remote unit (10) designated as the exclusive system talker will generate a surrogate relinquishment request to the communications manager (40) if the exclusive system talker travels outside the coverage area of the system, loses power, or is destroyed.

A wavelength rerouting algorithm in wide-area all-optical networks

Abstract: This paper considers rerouting and minimization of incurred disruption due to rerouting in a wide-area all-optical wavelength division multiplexed (WDM) network with random circuit arrivals and departures. One limitation of such a network is the wavelength continuity constraint imposed by the all-optical cross-connect switches which do not allow a circuit to be placed on a nonwavelength-continuous route. Wavelength rerouting is proposed to rearrange certain existing circuits to create a wavelength-continuous route in order to accommodate a new circuit. To reduce the disruption period, move-to-vacant wavelength-retuning (MTV WR) is used as the basic operation of circuit migration, in which a circuit is moved to a vacant wavelength on the same path, and parallel MTV WR rerouting is used to reroute multiple circuits. An optimal algorithm is developed to minimize the weighted number of rerouted circuits with parallel MTV WR rerouting. In our test network, wavelength rerouting can effectively alleviate the wavelength continuity constraint by reducing call blocking probability an average of 30 % while reducing the number of rerouted circuits and the disruption period,.

Method and apparatus for measuring link quality in a spread spectrum communication system

Abstract: The present invention is a method and apparatus for providing a received signal quality metric which is optimally designed to control the transmission power of a transmitter in a closed loop power control system. The present invention is described in the context of a spread spectrum communication system but it is equally applicable to other types of communication systems. In the present invention, the power control system is described for controlling the power of transmissions from a base station to a mobile station, referred to as forward link transmissions.

System and method for simulating interference received by subscriber units in a spread spectrum communication network

Abstract: A method and apparatus for simulating signal interference in one communication channel within a communication system, such as cellular or wireless subscriber telephone and/or data systems. The communication system may be of a cellular type in which users from a plurality of cells communicate information signals between one another using at least one base station and code division multiple access (CDMA) spread spectrum type communication signals. The base station is included in a first of the cells and has a transmitter from which information is transmitted to subscriber units over at least one communication channel. The disclosed method includes the step of determining a first composite signal energy associated with signal transmission from the base station transmitter over a first set of simulated communication channels. The simulation method further contemplates estimating a first average data rate for the first composite signal energy. Signal power transmitted over the one communication channel is adjusted in accordance with a first interference signal which is based on the first composite signal energy and first average data rate. In a preferred implementation, a determination is also made of a second composite signal energy associated with signal transmissions from base station transmitters in other cells over a second set of simulated communication channels. An estimate is also made of a second average data rate for the second composite signal energy to enable generation of a second interference signal.

Method and system for over-the-air (ota) service programming

Abstract: A communications network and method for over-the-air service programming a mobile station (2), where the mobile station transmits a service programming request to a communications network, which results in the mobile station (2) being connected to a customer service center (26). Customer service center (26) queries the user of mobile station (2) for information in response to which the customer service center (26) selects a home location register (18) and authentication center (22) within the communications network with which the mobile station (2) is to be associated. Service programming information associated with the mobile station (2) is transferred from the home location register (18) and/or the authentication center (22) into mobile station (2).

Time division duplex repeater for use in a cdma system

Abstract: A method and apparatus for time division duplex (TDD) repeating a spread spectrum signal, said spread spectrum signal comprised of a series of code symbol modulated with a pseudonoise (PN) sequecne. The TDD repeater receives intermittently the spread spectrum signal at a location remote from a source supplying the spread spectrum signal. The TDD repeater amplifies and delays the received spread spectrum signal by a predetermined amount. The TDD repeater transmits intermittently the delayed amplified received spread spectrum signal such that the TDD is not receiving the spread spectrum signal when it is transmitting the signal energy.

Performance evaluation of TCP/RLP protocol stack over CDMA wireless link

Abstract: Due to the high frame error rate in wireless communication channels, an additional link layer protocol, Radio Link Protocol (RLP), has been introduced in the newly approved Data Services Option Standard for Wideband Spread Spectrum Digital Cellular System. In this paper, we investigate performance issues of a typical Cod Division Multiple Access (CDMA) wireless link using the protocol stack given in the standard. In particular, we focus on the dynamics of the TCP and RLP layers of the protocol stack since the fluctuation of systemperformance is largely caused by Automatic Repeat Request (ARQ) mechanisms implemented at these two layers. We compare the network performance of default parameter setting to those of other possible parameter settings. Analytical and simulation results presented in this paper can provide guidance to those attempting to further improve performance of interest.

Method and apparatus for joint transmission of multiple data signals in spread spectrum communication systems

Abstract: A more efficient and less complex structure and method for combining multiple user channels onto a single carrier frequency in spread spectrum communication systems. A single transformation element, such as a fast Hadamard Transformation processor, is used to orthogonally encode and combine a series of subscriber digital data signals in parallel. Portions of the orthogonally encoded and combined data signals are then selected over preselected time intervals to generate a single encoded data signal which is subsequently PN spread, subjected to analog signal processing, and transmitted to system subscribers. This is typically effected by summing digital values in an array of data signal combiners. An exemplary data transformation device uses at least one of a preselected set of orthogonal functions as a controlling pattern for interconnection of the combining elements. Each of the combining elements receives at least two input signals, either data or previously combined data, and produces a combined encoded signal output. The order of combination maps the input data signals into an orthogonal combined signal. Portions of the combined data signals are then selected and transferred in order as a serialized data stream for subsequent spreading and transmission as a communication signal.

Two different philosophies in CDMA-a comparison

Abstract: There has been considerable interest recently in the subject of multiuser interference cancellation techniques for CDMA wireless systems. It is widely believed that a system design using interference cancellation techniques has considerably better capacity than the design methodology adopted in the IS-95 CDMA cellular standard, which does not use such techniques. We examine this issue, and in particular focus on linear interference cancellation techniques. Linear techniques are simpler and require fewer assumptions, such as accurate knowledge of amplitude and phase information of the users to be canceled, than nonlinear interference cancellers. However, linear interference cancellation techniques require a fundamentally different CDMA system design philosophy than IS-95. In IS-95, the coding gain from error control codes bears the burden of handling interference, while a linear canceller uses the dimensional separation of users. This paper compares and contrasts the two design philosophies. Our comparison is based on overall user capacity (defined as the number of users per Hz per unit area) as well as robustness and fairness. The focus of the paper is on the mobile-user to base station reverse link which is modeled by the classical many-to-one multiple-access problem.

Centralized forward link power control

Abstract: In a mobile communication system comprising at least two base stations coupled to a common base station controller, each base station with which a particular mobile station is communicating sends its received frame quality message to the common base station controller. The base station controller combines the received messages to provide an improved estimate of the correct message and thus a correct power level for the forward link signal. Each base station preferably responds independently to error messages it receives from the mobile station and also sends the error message to the base station controller. After receiving power control commands from the base station controller, the base station then determines whether it responded properly at the time when it received the error message from the mobile station.

System and method for determining received pilot power and path loss in a CDMA communication system

Abstract: A system and method for estimating the quality and path loss associated with a communications channel on the basis of the power of a pilot signal received by a communications receiver. The communications receiver measures a received signal power, and also makes a relative pilot strength measurement of a received pilot signal. The power of the pilot signal is then computed using the received signal power and the relative pilot strength measurement. An indication of channel quality based on the pilot signal power may be provided to a user of the communications receiver. Path loss of a communication channel between a base station and a remote site station is also estimated. The base station also transmits an indication of the power at which the pilot signal was transmitted. An estimate of the path loss is then made by determining the difference between the indicated power of the transmitted pilot signal and the received pilot signal power.

Method and apparatus for providing variable rate data in a communications system using statistical multiplexing

Abstract: The present invention discloses a variable rate transmission system wherein a packet of variable rate data generated by a variable rate data source (20) is modulated on traffic channel by traffic channel modulator (30) if the capacity of said traffic channel is greater than or equal to said data rate of said packet. The packet of variable rate data is modulated onto traffic channel by traffic channel modulator (30) and at least one overflow channel by traffic channel modulator (32) if the capacity of said traffic channel is less than said data rate. The present invention further discloses a receiving system for receiving variable rate data wherein a received packet of variable rate data is received on traffic channel if the capacity of said traffic channel is greater than or equal to a data rate of said packet and wherein a packet of variable rate data is received on traffic channel and at least one overflow channel if the capacity of said traffic channel is less than said data rate.

Performance evaluation of experimental 50-Mb/s diffuse infrared wireless link using on-off keying with decision-feedback equalization

Abstract: We report an experimental nondirected optical link for short-range, indoor data transmission at 50 Mb/s. The system uses on-off keying (OOK) and achieves low bit-error rates (BERs) in the presence of intersymbol interference, background light noise, and shadowing, with a range of 2.9 m in a skylit room. The transmitter produces an eye-safe Lambertian pattern at 806 nm with an average power of 474 mW. The receiver utilizes a hemispherical concentrator with a hemispherical bandpass optical filter, a 1-cm/sup 2/ silicon p-i-n photodiode, and a high-impedance hybrid preamplifier to achieve a high signal-to-noise ratio (SNR). A high-pass filter is used to mitigate fluorescent light noise, with quantized feedback removing the resulting baseline wander. A decision-feedback equalizer provides resistance to intersymbol interference due to multipath. The system and its components are characterized, and compared to theory. We observe that decision-feedback equalization yields a reduction of multipath power penalties that is in good agreement with theory.

Method for using only two base stations for determining the position of a mobile subscriber in a CDMA cellular telephone system

Abstract: A method for determining the position of a mobile station within a cellular telephone system having first and second base stations. A round trip signal propagation time between the first base station and the mobile station is measured at the first base station. A first signal is transmitted from the first base station to the mobile station, and a second signal is transmitted from the second base station to the mobile station. An arrival time difference representing a time interval between a first relative time when the first signal is received at the mobile station and a second relative time when the second signal is received at the mobile station is measured at the mobile station. The position of the mobile station is determined in accordance with the round trip propagation time and the arrival time difference. A method for determining the position of a mobile station within a cellular telephone system having first and second base stations. A first round trip signal propagation time between the first base station and the mobile station is measured at the first base station. A second round trip signal propagation time between the second base station and the mobile station is measured at the second base station. The position of the mobile station is determined in accordance with the first and second round trip propagation times.

Multiple satellite repeater capacity loading with multiple spread spectrum gateway antennas

Abstract: A communication system (10), and a method executed by same, for allocating communications traffic through a plurality of satellites (12) of a constellation of low earth orbit satellites. Each of the plurality of satellites is oriented, at any given time when in view of a ground station (18), at a particular elevation angle. The method comprises the steps of: (a) providing each of the plurality of satellites with a receiver for receiving communication links from the ground station and a transmitter for transmitting communication links to user terminals; (b) in response to a request for service, determining if a highest elevation angle satellite can be assigned a new communications link; (c) if yes, assigning a new communication link to the highest elevation angle satellite; (d) if no, determining if a second highest elevation angle satellite can be assigned a new communications link; and (e) if yes, assigning a new communication link to the second highest elevation angle satellite. A number of different criteria can be employed in determining if a satellite can be assigned a new communication link, including: determining if the associated satellite has already been assigned a predetermined maximum number of communication links; and determining if the associated satellite, or a particular beam, is transmitting at or near to a power level that corresponds to a maximum peak flux density at the surface of the earth. Each of the steps of assigning is preferably accomplished such that the communication link is simultaneously established through at least two of the satellites to provide for diversity reception at a user's terminal (13).

Simulating user interference in a spread spectrum communication network

Abstract: A method and apparatus for simulating signal interference within a communication system, such wireless or cellular communication systems. The communication system is preferably of a type in which code division multiple access (CDMA) spread spectrum communication signals are used. The method for simulating signal interference power received by a base station receiver includes estimating a first composite signal power corresponding to the sum of signal power transmitted by a first set of simulated users located in a first cell. An estimate is also made of a first normalized date rate for transmission of the composite signal. A first interference signal is then generated at a power level determined on the basis of the first composite signal power and normalized data rate. In a preferred implementation, the first interference signal power is adjusted in accordance with an average power fluctuation arising as a consequence of closed loop power control. Further, a second composite signal power is determined by estimating the sum of signal power transmitted by a second set of simulated users located outside of the first cell. A similar estimate is made of a second normalized data rate at which this signal power is transmitted by the second set of simulated users. This allows the generation of a second interference signal based on the second composite signal power and normalized data rate. Generation of the first interference signal will typically involve synthesis of electrical noise over a predetermined frequency band. The power of the electrical noise is then adjusted in accordance with the product of the first composite signal power and the first normalized data rate.

Power-efficient acquisition of a CDMA pilot signal

Abstract: A system and method for acquiring a code division multiple access (CDMA) pilot signal having a pilot pseudonoise (PN) code offset in a CDMA communication system. A received signal is correlated with a first set of PN code offset hypotheses. If this first "full" search is unsuccessful in acquiring the CDMA pilot signal, the method includes waiting for a first period, and then correlating the received signal with a second set of PN code offset hypotheses which are a subset of said first set of PN code offset hypotheses and therefore requires less search time. If this "mini" search is unsuccessful in acquiring the CDMA pilot signal the method includes waiting for a second period and then quickly measuring the energy of the received signal. If the received energy exceeds a threshold, then a "mini" search is immediately performed. These alternating search techniques of full, mini, micro are repeated.

Long-pulse and CW tests of a 110-GHz gyrotron with an internal, quasi-optical converter

Abstract: A high-power gyrotron, employing an internal converter that produces a Gaussian-like output mode, has been designed and tested. The tube employed a TE/sub 22.6.1/-mode interaction cavity that was designed for operation at a frequency of 110 GHz. An internal converter, consisting of an advanced launcher design and four mirrors, produced a Gaussian mode that had a relatively uniform profile at the tube output window to minimize the peak power density. Tests on the tube resulted in output power levels of 680, 530, and 350 kW for pulse durations of 0.5, 2.0, and 10.0 s, respectively. Measurements of the temperature of the output window were made during the long-pulse tests. Output power levels of 1 MW were achieved under short-pulse (1 ms) operation and the tube was operated at CW power levels in excess of 100 kW.