Abstract: A method for use by a receiver of a wireless communication system in providing information of use in adapting to changing characteristics of a communication channel (22) over which the receiver (23) receives a signal at an offset from a carrier frequency due to changes in the characteristics of the communication channel characteristics, the changing communication channel characteristics also causing from time to time changes in other characteristics of the communication channel (22), the method characterized by: a step (23b-1a 23b-1b) of providing expectation maximization estimates of autoregressive parameters representing the changing communication channel (22) using received signal samples extracted from the received signal and corresponding to transmitted pilot symbol; and a step (23b-1a 23b-1c) of providing an estimate of the channel impulse response and an estimate of a frequency offset of at least one multipath signal based on the estimated values of the autoregressive parameters.

Abstract: The present invention relates to a method for adaptively controlling a transmission radiation pattern. Radio signals coming through a plurality of paths are received and demodulated for each path. The received level or received quality of each demodulated signal is compared to each other to select a signal with the highest level or most excellent quality. A path corresponding to a selected path is set at a path for transmission. When a plurality of signals each with an almost equal level or received quality exists in signals demodulated for each path, a history of transmission power control command (TPC) transmitted from a communication partner is referred. In other words, the reception condition in a communication partner is checked. Thereby, it is judged whether or not the currently selected path is appropriate as the path for transmission.

Abstract: A wireless communication system includes at each cell at least one network part of the system communicating with subscriber terminals in its area. Within the system, a method for transmitting reception information on a receiving end to a transmitter includes measuring the quality of a signal received from a terminal, such as the bit error ratio (BER) of the signal, and transmitting the measured quality information to the terminal to be indicated to the user of the terminal, or transmitting an announcement selected on the basis of the quality information to the terminal via the network part to be indicated to the user.

Abstract: The present invention pertains to the field of methods and apparatuses relating to radio communication; and in particular to the part of this field that concerns cellular radio communication. The present invention addresses mainly the problem of improving reliability and communication quality in a cellular radio communication system (1). According to the invention, it is determined whether one of an uplink (25) or a downlink (25) of a radio channel (23) is subject to a Rayleigh fading dip. If it is determined that one of the uplink (25) or the downlink (27) is subject to a Rayleigh fading dip, it is then determined whether it is necessary to execute a countermeasure in order to avoid the negative influences of Rayleigh fading on the channel (23). The invention is not limited to improving conditions on one channel but may be employed to any number of channels used for communications in the cellular radio communication system (1).

Abstract: In a RAKE receiver delays associated with multipath signals are determined by subtracting power values associated with sidelobes of a peak value for each of the multipath signals. The determination can be performed in two stages, in the first stage the determination of the delays is made without accounting for a phase difference between adjacent multipath signals, while in the second stage the determinations are made accounting for the phase difference.

Abstract: A method for assigning tracking elements includes sorting a list of potential assignments according to a diversity criterion. In one example, a list of received signal instances is sorted first according to a measure of energy and then sorted again according to the diversity criterion. In a further embodiment, a demodulation element may be labeled available for assignment yet continue to output demodulated symbols in a locked state. Applications to a mobile station of a CDMA system for cellular telephony are discussed.

Abstract: A communication mode determination section 201 determines the communication mode based on the CIR measured by a CIR measurement section 219; a DRC signal creation section 202 creates a DRC signal with a number corresponding to the communication mode; and a DRC power controller 205 refers to a transmission power table 206 showing the correspondence between DRC numbers and transmission power, and, based on the transmission power of the pilot signal output from a pilot power controller 209, increases transmission power in proportion as the DRC signal indicates that downlink channel quality is good.

Abstract: A position location communication system determines the position of a mobile master radio using a round-trip messaging scheme in which the time of arrive (TOA) of ranging signals is accurately determined to yield the range estimates required to calculate the position of the mobile radio. The master radio transmits ranging signals to plural reference radios which respond by transmitting reply ranging signals. Upon reception of the reply ranging signal, the master radio determines the range to the reference radio from the signal propagation time. Any combination of fixed or mobile radios having known positions can be used as the reference radios for another mobile radio in the system. Individual radios do not need to be synchronized to a common time reference, thereby eliminating the need for highly accurate system clocks. Errors in TOA estimates are minimized by performing internal delay calibration, Doppler compensation, leading-edge-of-the-signal curve fitting and frequency diversity techniques.

Abstract: Improved signal reception is provided in a digital television signal received by identifying and mitigating multipath signal effects prior to demodulation and equalization. According to an exemplary embodiment, a digital television signal is received having multipath signal effects which cause a plurality of ripples in the received signal. The amplitude of at least one of the ripples and the frequency separation between at least two of the ripples are detected. At least one of an antenna and a tuner is controlled in dependence upon the detection. Signal demodulation and equalization operations may be performed after at least one of the antenna and the tuner is controlled.

Abstract: The mobile terminal of the present invention receives signals from the base station which receives the control command from the mobile terminal and executes, on the basis of the control command, the antenna switching transmission diversity. The mobile terminal includes: a reception unit for receiving downward signal from the base station; a downward link estimation unit for estimating the downward link on the basis of the received downward signal; an upward link estimation unit for estimating the upward link on the basis of the received downward signal; a base station estimation unit for estimating a state of the base station on the basis of the outputs from the downward estimation unit and the upward estimation unit; and a demodulator unit for demodulating the received signal on the basis of the output from the base station estimation unit.

Abstract: Methods of designing, installing and operating communications systems including multiple input multiple output (MIMO) antenna arrays are disclosed. The methods account for the diffusive nature, the polarization nature, and the multi-path nature of the environment in which the antenna arrays operate. According to the various methods, the antennas can be designed, installed and operated so as to provide improved information capacity based on the diffusive, polarization and multi-path nature of the environment in which they operate.

Abstract: The invention relates to a method for use in wireless data communications for facilitating two way data transfer between devices employing frequency diversity. It is generally suited toward units accomplishing frequency diversity by way of frequency hopped spread spectrum operation. The basic unit of the invention is an individual data frame whose reliability is enhanced by a unique combination of redundant error correction coding, time-, and frequency-diversity. The invention further extends the individual data frame concept to a complete asynchronous data message which comprises both a call establishment phase and a traffic phase. The traffic phase extends the basic data frame to encompass a complete data message. That message, which already contains the enhancements of the basic data frame, is further enhanced by repeating itself as many times as can fit in the transmission.

Abstract: A radiocommunication apparatus, a radiocommunication system, and a radiocommunication method adapted to a radio network system for attaining synchronism of a reception signal, which contains a plurality of synchronism attainment signals representing the same pattern of bits, relative to a reference signal, in which the autocorrelation function of the reception signal and the cross-correlation function thereof are detected, and the synchronism attainment signals contained in the reception signal are detected based on the detected autocorrelation function and cross-correlation function. Consequently, a receiving side can reliably detect the synchronism attainment signals.

Abstract: A CDMA receiver includes a Rake reception circuit for performing in-phase synthesis of reception signals from a plurality of paths. In this receiver, a delay profile indicating a signal power distribution with respect to delay times of the reception signals is measured. An interference wave power value is estimated on the basis of the measured delay profile. Valid data are extracted from the delay profile on the basis of the estimated interference wave power value. A plurality of correlation peak positions are detected from the extracted valid data. Path allocation to the Rake reception circuit is determined on the basis of the correlation peak positions. A path detection method and recording medium which records a path detection control program are also disclosed.

Abstract: A method of selecting a soft symbol for a subsequent operation in a communication device is disclosed. In one embodiment, a signal is received at the communication device. Next, the signal is demodulated. Then, a strength level such as a signal to noise ration Eb/Nt is determined. Based upon the strength level determined for the signal, a location of bits of the signal is determined for a subsequent operation. The strength level and the location of bits is adaptively updated for the signal over time.

Abstract: There is provided a channel estimating apparatus and method in a radio communication system.

Abstract: An amplifier system having an amplifier for amplifying a communications signal, a scanning receiver for monitoring a signal strength of the communications signal, a microprocessor for determining, based on the signal strength of the communications signal, whether the communications signal should be amplified, and a switch, controlled by the microprocessor, for allowing the communications signal to pass through the amplifier or be terminated.

Abstract: A transmitter broadcasts a signal having a different code characteristic for each of several directions. A receiver receives the broadcast signal from one of the directions and generates an expected signal for that direction based on the code characteristic for that direction. The receiver detects the broadcast signal from the direction based on the expected signal for that direction.

Abstract: A receiver for a CDMA mobile radiocommunication system, receiving a signal which is a superposition of different signals, or path signals, corresponding to different propagation paths of a transmitted signal, which in turn is a superposition of different signals, or channel signals, corresponding to different channels carrying different transmitted informations, said receiver comprising, prior to the recovering of the transmitted information carried by a given channel, by exploiting said different propagation paths: means (6, 9) for estimating at least one received channel signal, or interferer signal, which is a superposition of different path signals corresponding to different propagation paths of a transmitted channel signal corresponding to at least one channel different of said given channel, means (10) for substracting said at least one estimated interferer signal, from said received signal.

Abstract: A method and wireless communication system for identifying one or more undesired signals at a multiple input receive unit receiving a desired signal or several desired signals and the undesired signal or signals. A separability condition between the desired signal and undesired signal is provided to enable that the undesired signal can be identified at the multiple input receive unit. The separability condition includes the use of substantially coherent reception at the receive unit and the use of separable training patterns for the desired and undesired signals. Zero tones are included in desired and undesired signals to further enhance signal separability. Signal training at the receive unit is used to derive the corresponding channel matrices for the interferers and mitigate their effects.

Abstract: A method for directing an antenna beam, and a transceiver which comprises antenna arrays forming antenna beams in the transmission direction, by means of which beams a signal is transmitted, and which receives signals that propagate via different paths to the transceiver. The transceiver comprises estimating means for estimating directions of arrival of the received signals, when the transceiver receives signals propagated via different paths, measuring means for measuring the strengths of the signals received from different paths of arrival, and beam directing means. The directing means command the antenna array to form in the transmission direction the main antenna beam which is formed in the direction wherefrom the strongest signal is received, if the directions of arrival of the received signals differ only slightly from one another.

Abstract: The prior art teachings for encoding signals and transmitting them over a plurality of antennas are advanced by disclosing a method for encoding for any number of transmitting antennas.

Abstract: The present invention discloses a method for predicting fast fading using sinusoidal modeling techniques. The method first applies a finite impulse response low pass filter to the incoming signal thus increasing the fading power to noise ratio. Applying a root-MUSIC frequency estimation model, a sinusoidal model for the fading process is obtained. This model can be used to enhance the performance of spatial diversity schemes or temporal processing schemes to reduce the effect of the fading.

Abstract: A search receiver within a wireless communicator uses an adaptive path detection threshold.

Abstract: A method for code tracking RAKE receiver fingers, the method comprising: taking several successive samples from a received signal, combining sample values measured in different fingers into measurement value sets, comparing the measurement value sets with each other and selecting the measurement value set having the highest value from among the measurement value sets meeting a minimum delay distance condition for the fingers, if any one of the sample values of the selected measurement value set is earlier than an on-time sample value determined on the basis of code phase acquisition, advancing the sampling or code phase of the particular finger, and if any one of the sample values of the selected measurement value set is later than an on-time sample value determined on the basis of code acquisition, delaying the sampling or code phase of the particular finger.

Abstract: Various techniques for improving a wireless communication device are described. The techniques may include reducing power in a wireless communication device for a first sleep period and then increasing power in the wireless communication device for an intermediate wake period after the first sleep period to estimate an error of the sleep clock. The method may further include reducing power in the wireless communication device for a second sleep period after the intermediate wake period. The intermediate wake mode implemented during the intermediate period can be used to estimate the error of the sleep clock without performing one or more tasks associated with an awake mode, such as demodulation. The techniques may facilitate the effective use of low frequency low power clocks for sleep mode, even when relatively large slot cycles are defined within a slotted paging system.

Abstract: A device and a method at a mobile communication system which provide a flexible and realistic way of emulating the time dispersive qualities and the broadband frequency correlation qualities of a radio channel. The device includes two or more flexible delay modules, and each module is arranged to emulate a tap and a continuously varying tap attenuation can be attained to describe the variation of the radio channel over the time. The modules may be realized in SAW-technology, and continuously varying tap attenuation may be achieved by the utilization of PIN-diode attenuators.

Abstract: Closed loop multiple-antenna wireless communications system with antenna weights determined by maximizing a composite channel signal-to-interference-plus-noise ratio minimum. Multiplexed symbol streams over subsets of antennas enhance throughput.

Abstract: A transmitter broadcasts a signal having a different code characteristic for each of several directions. A receiver receives the broadcast signal from one of the directions and generates an expected signal for that direction based on the code characteristic for that direction. The receiver detects the broadcast signal from the direction based on the expected signal for that direction.

Abstract: A method for efficient power control in a (CDMA based) fixed wireless system. The method comprises the steps of (1) monitoring a transmission link of the fixed wireless system for an occurrence of a fade, (2) recording a number of power increases to the transmission link due to said fade, and (3) reducing the power to an appropriate level when said fade is over. The adjusting step includes the steps of determining an appropriate power-down step size, which results in saving power, wherein the step size is influenced by a frame error rate (FER) and selected to maintain a desired FER, and dynamically decreasing the power by the appropriate power-down step size, thereby conserving power and increasing system capacity.

Abstract: A method and system for performing multicast broadcast handover in a wireless data network are disclosed. Each cell broadcasts administrative announcements over a logical channel to mobile terminals. The announcements indicate which multicast broadcasts are available in specified cells, as well as connection information for each cell. The mobile terminals may tune to a multicast broadcast as defined by the administrative announcements. While tuned to the multicast, the mobile terminal continues to receive administrative announcements. As the broadcast fades out or is otherwise interrupted, the mobile terminal can retune to the same multicast broadcast in another cell, based on the cell connection information included in the previously received administrative announcements.

Abstract: A method, apparatus and computer program product for predicting received signal strength in a wireless mobile receiver. The invention bounds the range of allowed values for a next predicted signal. The bounded prediction compensates for erroneous values from multipath fading. The predicted signal strength is used to set the mobile receiver amplifier gain to the desired level.

Abstract: A receiver and an associated method are disclosed for combining signals having substantially different polarizations. The receiver is used with a first antenna which receives first polarized signals and a second antenna which receives second polarized signals, the first polarized signals having a substantially different polarization than the second polarized signals. The receiver includes a phase shifter and a combiner circuit. The phase shifter adjusts the phase of the first polarized signal in response to the phase of the second polarized signal to produce a phase compensated first signal. The combiner circuit sums the second polarized signal and the phase compensated first signal to generate a combined polarization received signal. In this manner, the depolarized signals are phase-aligned with, and then combined with, the polarized signals to provide a strong received signal irrespective of any depolarization of the received signal.

Abstract: The time of arrival of a received signal with multipath components is precisely estimated using an optimal algorithm, such as Maximum Likelihood Estimation (MLE), after restricting the optimal algorithm's search space to one or more time intervals determined by preprocessing the received signal using a less computationally complex sub-optimal algorithm. This approach yields the accuracy benefits of optimal algorithm processing, while reducing aggregate computational complexity. Sub-optimal algorithms include but are not limited to correlation, MUSIC, and Signal-Eigen-Vector (SEV) processing. Iterative sub-optimal pre-processing of the received signal further refines the optimal algorithm search space, and, in some instances, may be used to resolve multipath time-of-arrival (TOA) with sufficient accuracy.

Abstract: The communication system executes one-to-multi peer communications between a master station (A) and many salve stations (B1, B2) by using outgoing and incoming communication media (7, 4). The master station (A) includes a data transmission processor 1, a data reception processor 2, a receiving circuit 3, the incoming communication medium 4, a multiplexer 5, a transmission circuit 6, the outgoing communication medium 7, a delay measuring unit 8, a transmission timing calculator 9, a transmission permission signal generator 10, and a system controller 11. Communications are carried out with the slave stations (B1, B2) by using the outgoing communication medium 7, and delays (d1, d2) until the master station (A) are respectively measured. A transmission interval of signals for giving transmission permission to the slave stations is obtained. The signals for transmission permission are transmitted to the slave stations (B1, B2) based on the transmission interval.

Abstract: A mobile receiver, located within a vehicle, exhibits improved signal processing in the presence of multi-path distortion. Initially, the speed of the vehicle is determined. Next, signal information on a selected signal received by the mobile receiver is collected. The collected signal information provides an indication of the quality of the received signal. Then, at least one time constant associated with the processing of the collected signal information is modified responsive to the determined speed.

Abstract: Direct-path-signal (DPS) detector circuitry includes a standard deviation calculator circuitry configured to determine a standard deviation of a plurality of data values within a data frame. The data frame corresponds to a radio-frequency signal received via a communication link. The DPS detector circuitry also includes a threshold circuitry configured to detect a direct-path signal depending on the relative values of the standard deviation and a threshold signal.

Abstract: Systems and methods are described that provide global positioning system (GPS) enabled wireless communications. The wireless communications system provides a switching module that is adapted to couple communications circuitry to a first antenna or a second antenna as a function of communications characteristics of the first antenna or the second antenna. The switching module is also adapted to couple GPS circuitry to a first antenna or a second antenna as a function of GPS reception characteristics of the first antenna or the second antenna. The switching module may also provide the communications circuitry and the GPS circuitry with simultaneous access to different antennas.

Abstract: A system and a method for receiving and transmitting information in a multipath environment provide a wireless communications system. The wireless communications system provides a switching module that is adapted to couple a receiver module to either a first antenna or a second antenna as a function of reception characteristics of the first antenna and the second antenna. The switching module is also adapted to couple a transmitter module to the either the first antenna or the second antenna as a function of transmission characteristics of the first antenna and the second antenna.

Abstract: Techniques to determine the position of a terminal under the coverage of a repeater in a wireless communication system. In an aspect, an identification code is transmitted for each repeater and used by the terminal (or a PDE) to unambiguously identify the repeater. The identification codes for the repeaters in the system can be implemented with PN sequences at defined offsets that are specifically reserved for repeater identification. In another aspect, the identification code for each repeater is transmitted using a spread-spectrum signal designed to have minimal impact on the performance of the system and to be recoverable by the terminal in similar manner as for a forward modulated signal. In this way, no additional hardware is required for the terminal to recover the identifier signal. In one specific design, the spread spectrum identifier signal is generated in accordance with and conforms to the IS-95 CDMA standard.

Abstract: The present invention discloses a method for predicting fast fading using sinusoidal modeling techniques. The method first applies a finite impulse response low pass filter to the incoming signal thus increasing the fading power to noise ratio. Applying a root-MUSIC frequency estimation model, a sinusoidal model for the fading process is obtained. This model can be used to enhance the performance of spatial diversity schemes or temporal processing schemes to reduce the effect of the fading.

Abstract: A method, executed on a simulation system (20), characterizes propagation of a radiofrequency signal (56) in a three-dimensional environment (52). The method includes forming a database (42) of propagation paths (54) of the radiofrequency signal (56) transmitted from a transmitter (58) at a fixed location (66) in the three-dimensional environment (52). The propagation paths (54) are represented by a plurality of line segments (120, 122) in the database (42). Local line segments (188) are selected from the plurality of line segments (120, 122) to establish a subset (47) of the propagation paths (54). The subset (47) includes those propagation paths (54) each having one of the local line segments (188) proximate a location (182) of a receiver (72) in the environment (52). Distinct multipath components (246) representing distinct wavefronts of the radiofrequency signal (56) are subsequently identified from the subset (47) of the propagation paths (54).

Abstract: A spread spectrum position location communication system determines the position of a mobile master radio using a round-trip messaging scheme in which the time of arrive (TOA) of ranging messages is accurately determined to yield the range estimates required to calculate the position of the mobile radio via trilateration. The master radio transmits outbound ranging messages to plural reference radios which respond by transmitting reply ranging messages. Upon reception of the reply ranging message, the master radio determines the range to the reference radio from the signal propagation time calculated by subtracting the far-end turn around time from the round-trip elapsed time. Any combination of fixed or mobile radios of known positions can be used as the reference radios for another mobile radio in the system, thereby providing adaptability under varying transmission conditions.

Abstract: A method and apparatus for adaptively adjusting the power of a probe signal to be transmitted by user equipment based on a characteristic of received signals and system constants so as to increase the likelihood that the probe signal will be detected by system equipment of a communication system. The Doppler shift of a received pilot signal is derived and an adjustment parameter is calculated based on the Doppler shift, time interval between successive probe transmissions, and system constants. The adjustment parameter is applied to the probe signal to be transmitted to compensate for the effects of fading to be experienced by the probe signal to be transmitted.

Abstract: A mobile station of a two-frequency simplex radio communication system, in which communication between a base station and each mobile station is performed in such a manner that the base station continuously transmits packet data whereas each mobile station transmits burst data. The mobile station includes a radio wave propagation path condition detector for detecting the condition of a radio wave propagation path used for communication, and a communication control circuit which, when it is determined based on the condition of the radio wave propagation path detected by the radio wave propagation path condition detector, that transmission or reception timing cannot be obtained within a predetermined period of time, adaptively selects a transmission mode and notifies the base station of the selected transmission mode so as to receive data which is transmitted from the base station after the notification.

Abstract: The invention relates to a method of determining the average effect of radio wave multipath fading in a desired area in a radio system. The desired area of a coverage area of a base station in the system is described by a digital map. The average effect of multipath fading of a transmitter output is determined in different sub-areas of the desired area. In order to reduce the computation amount signal fading parameters are determined at some point of each sub-area by a ray tracing method and the average effect of signal multipath fading in the sub-area is calculated using said parameters.

Abstract: In the preferred embodiment, the transmission length of the non-full rate frame is shortened frame in order for the mobile terminal 100 to monitor other frequencies with a single receiver. Modulated symbols of non-full rate frame are transmitted with reduced repetition maintaining the sum of repeated symbol energy. Generally, for 1/n (n=2,4,8) length transmission, 1/m (m≧n) rate frame repeated m/n times and transmitted with n/m symbol energy of the full rate frame. The system may use rate limitation to generate a non-full rate frame. A position of the transmitted symbols may be randomized by a mobile specific predetermined random code to minimize interference between terminals different from each other. For intensive frequency scanning and synchronization signal transmission, non-transmitting period can be assigned for successive frames of some interval.

Abstract: Multipath propagation detection can be accomplished using first and second spaced antennas which receive a carrier signal from a moving radiation source and produce a carrier phase difference representative of the location of the source; a difference signal representative of the difference between the measured carrier phase difference and a predetermined phase difference for the source in that location is generated; and the presence of multipath distortion in that difference signal is determined. Furthermore, when a multiplicity of source signals are tracked as in reception of navigation signals from the Global Positioning Satellite System, the receiver may be programmed to eliminate or suppress errors arising from measurements that have been distorted by multipath propagation.

Abstract: A secondary station has a receiver capable of resolving signals received (504,510) as a plurality of multipath signals from a plurality of base stations during a soft handover process. In order to decode and act upon the received signals in a very short period of time, an initial subset of received multipath signals is processed (506) to provide an estimate of the action needing to be taken by the station, which action is then implemented by the station (508). Later arriving signals are processed separately (512) and used to update the estimate, as a result of which the action already taken may be corrected (514).

Abstract: A device for ensuring that the amplitude of signals fall within a predetermined range, said device comprising input means for receiving a plurality of input signals at substantially the same time, a first path for increasing the amplitude of any of the input signals having an amplitude below a first threshold, a second path for decreasing the amplitude of any of the input signals having an amplitude which exceeds a second threshold and combining the outputs of the first and second paths to provide a plurality of signals having amplitudes between said first and second thresholds.