Abstract: A method and corresponding apparatus for searching for a signal is presented. The apparatus may be configured to select a first bin within a range of bins characterizing an uncertainty region. The bins may represent a phase within a bandwidth of interest. The apparatus may also be configured to compare a local signal, having a phase corresponding to the first bin, with a received signal, the received signal being received via a transmission medium. The apparatus may report whether the local signal matches the received signal. The apparatus may assign weightings to the bins if the local signal does not match the received signal. If a match is not found, the apparatus may select a next bin according to the weightings or according to characteristic of the transmission medium until a matching bin is obtained. One benefit of the search is reduced search time to allow, for example, a cell phone to synchronize the phase of a received signal more quickly than is currently done.

Abstract: A system (170) and method (300) for ray launching is provided. The system can include a transmitter (110) for successively launching a plurality of rays, and a receiver (120) for receiving transmission rays and reflection rays. A controller (141) can be included for selectively adjusting an angular spacing and eliminating rays in successive launches to focus an energy on the receiver. A method (430) of terminating rays for reducing computational complexity is provided. A method (340) for ray weighting for increasing a computational speed of ray propagation is provided. In one aspect, a quality of service (108) can be determined at the receiver based on ray propagation.

Abstract: The present application describes a method and system for determining a time delay between a transmission and a reception of an RF signal in a noisy environment. The method comprises: transmitting the RF signal; shifting a phase of the RF signal after a first time period of the transmitting of the RF signal, starting at a known transition time; receiving a received RF signal comprising a received phase shift corresponding to the shifting of the phase of the transmitted RF signal, the received phase shift occurring at a receive transition time equivalent to a sum of the time delay and the known transition time; determining the receive transition time by detecting a time corresponding to the received phase shift; and calculating the time delay using the receive transition time and the known transition time.

Abstract: A system and method for determining a signal propagation delay between a transmitter and a receiver, and for adjusting a transmission time based on the propagation delay. A central station inserts a marker into a transmitted signal at a time corresponding to a received timing signal. The MCT receives the signal from the central station and determines a time difference between receipt of the marker and the detection of the time interval event. A transmission by the MCT is adjusted by an amount of time proportional to the time difference.

Abstract: A phase-locked-loop device includes a clock generator for generating a reference clock based on a binarized playback signal and a frequency of run-length data and for generating N-phase clocks using the reference clock, a pulse-length measuring device for measuring a pulse length of the binarized playback signal using the N-phase clocks to output pulse-length data, and a run-length-data extracting device for counting the pulse-length data based on a virtual channel clock to extract run-length data. Pulse-length data is generated using the N-phase clocks (e.g., 16-phase clocks). The pulse-length data is counted based on the virtual channel clock to extract run-length data. Thus, it is not needed to generate a high-frequency clock, and the operating frequency is maintained sufficiently low.

Abstract: A method is provided for analyzing data transmission throughput in a wireless LAN of a multi sector environment. The method may include determining a sum of symbols of all sector switch guard times and propagation delay guard times of a MAC frame. The method may also include subtracting the number of determined symbols, the number of symbols of a signaling PDU and the number of symbols of a data PDU except a LCH from the number of symbols set in the MAC frame. Still further, the method may include displaying data transmission throughput by using a subtraction result value. Accordingly, by calculating the number of symbols occupied only by a LCH except sector switch guard times and propagation delay guard times, data transmission throughput can be accurately analyzed.

Abstract: A method of timing in a multi-cell system requiring synchronization of frames in transmission is provided. Transceivers of a wired data interface between a central controller and multiple base stations are synchronized to a frame timing clock up to a difference in propagation delays between the central controller and multiple base stations. The propagation delays are considered as constants, are measured, and are stored in each base station. A unique word is regularly inserted in the data transmitted by the central controller, at a fixed interval. When this unique word is detected by the base station within a fixed period of the frame timing clock, a frame signal delay is initiated at the next rising edge of each frame timing clock. This frame signal delay is equal to the period of the frame timing clock minus the propagation delay. At the end of the frame delay, the frame data is transmitted, and all frames are simultaneously transmitted from different base stations.

Abstract: A phase shift section phase-shifts the second band-restricted signal to a first phase-shifted signal and a second phase-shifted signal having a phase that is different from the phase of the first phase-shifted signal by 90 degrees. A first signal mixing section mixes the first band-restricted signal and the first phase-shifted signal. A second signal mixing section mixes the second band-restricted signal and the second phase-shifted signal. A phase difference calculation section calculates the phase difference value from the first mixed signal and the second mixed signal stripped of frequencies other than a desired baseband frequency. A polarization calculation section calculates reception polarization from the first reception field intensity value, second reception field intensity value and phase difference value.

Abstract: A Base Station (BS) apparatus for estimating a velocity of a Mobile Station (MS) in a mobile communication system includes a channel estimator for performing channel estimation according to a velocity band, receiving a wireless channel signal from the MS, and performing channel estimation using channel estimation coefficients optimized for individual velocity bands; and a velocity estimator for dividing the velocity band into a plurality of sub-Doppler bands, detecting a sub-Doppler band including a frequency index having a maximum frequency response from among the divided sub-Doppler bands, and transmitting information of the detected sub-Doppler band to the channel estimator such that a channel estimation coefficient corresponding to the information is transmitted.

Abstract: An electrical circuit to add and subtract differential input signals may be implemented using distributed differential transmission lines having a length substantially equal to one quarter of a wavelength of the differential input signals according to an effective electrical permeability of the transmission line. Alternatively, the electrical circuit may be implemented with lumped reactive elements.

Abstract: A system and method for correcting for Doppler shift in transmitted and received electromagnetic wave, light wave, or acoustic wave signals between two platforms, where at least one of the platforms is moving relative to the other. The system involves determining a Doppler shift that affects the frequency of a signal being transmitted from a transmitting platform, as a result of motion of the transmitting platform, and adjusting the frequency of the transmitted signal to cancel out the determined degree of Doppler shift that will be experienced by the receiving platform. If the receiving platform is also moving, then a determination is made as to the Doppler shift that will be imparted to the signal being received because of motion of the receiving platform. A receiver on the receiving platform is controlled to account for this degree of Doppler shift. Therefore, the Doppler shift components attributable to the motion of each, or both, platforms is accounted for.

Abstract: There is disclosed a simulator for mobile terminals within the context of a wireless network, for the purpose of testing the basestations. Channel impairments are effected during baseband processing.

Abstract: The present invention provides a method and an apparatus for detecting at least one repeater between a base station and a mobile unit. The method includes determining a first estimate of a distance traveled by a signal on a wireless communication link between the base station and the mobile unit, determining a second estimate of the distance traveled by the signal on the wireless communication link between the base station and the mobile unit, and comparing the first and second estimates. The method also includes determining whether the signal was processed by the at least one repeater based upon comparing the first and second estimates.

Abstract: The apparatus measures timing variations, such as the jitter or wander in a timing signal (100) of a telecommunications network. A recovered clock signal is sampled and digitized to produce a series of digital clock samples which are then processed (135) with reference to a local digital reference signal to produce digital baseband frequency in-phase (I) and quadrature (Q) components (165, 170) these being further processed (145) to produce the digital phase information of said clock signal to determine (175) the required parameters of the network. The step of digitally processing said clock samples with reference to a local reference signal can be conveniently and cheaply implemented using a digital signal down-converter IC (135), for example of a type existing for digital radio receiver implementations. For jitter measurement, the local reference signal may be generated by a phase-locked loop (as in FIG. 2). For wander measurements an external reference clock is used (as in FIG. 3).

Abstract: A system and method for assisting an integrated GPS/wireless terminal unit in acquiring one or more GPS satellite signals from the GPS satellite constellation. The invention includes a method for narrowing the PN-code phase search. That is, by accounting for the variables in geographic location and time delay relative to GPS time, the systems and methods of the present invention generate a narrow code-phase search range that enables the terminal unit to more quickly acquire and track the necessary GPS satellites, and thereby more quickly provide accurate position information to a requesting entity.

Abstract: An apparatus and associated methods to perform intelligent transmit power control with subcarrier puncturing in a multicarrier wireless communication channel is generally disclosed.

Abstract: Possible deficiencies of a communication link are detected and automatically counteracted, at least to some degree. The deficiencies addressed can include phase shift and attenuation compensation. The counter-action can include adjustment of pre-emphasis given a signal applied to the communication link and/or adjustment of equalization given a signal received from the communication link.

Abstract: Techniques to correct for phase and amplitude mismatches in a radio device in order to maintain channel symmetry when communicating with another device using MIMO radio communication techniques. Correction for the amplitude and phase mismatches among the plurality of transmitters and plurality of receivers of a device may be made at baseband using digital logic (such as in the modem) in the receiver path, the transmitter path or both paths of that device. In a device, amplitude and phase offsets are determined among the plurality of radio transmitter and radio receiver paths by measuring phase and amplitude responses when supplying a signal to a transmitter in a first antenna path of the device and coupling the radio signal from a first antenna to a second antenna path of that device where the signal is downconverted by a receiver associated with the second antenna path, and similarly coupling a signal from the second antenna path to the first antenna path.

Abstract: A transmit channel (gt1, h, gr2) through which a first wireless communication transceiver is to transmit to a second wireless communication transceiver can be estimated using information indicative of a relationship between the transmit channel and a receive channel (gt2, h, gr1) through which the first wireless communication transceiver receives communications from the second wireless communication transceiver. The relationship information (35) is combined (37) with further information (31) to produce an estimate of the transmit channel.

Abstract: A phase rotation unit rotates the phase of a digital received signal in accordance with a correction signal from a correction determination unit. An FWT computation unit subjects a CCK modulated signal to FWT computation and outputs Walsh transform values FWT. A maximum value searching unit receives Walsh transform values FWT and selects one of them by referring to the magnitude thereof. In accordance with the selected Walsh transform value FWT, the maximum value searching unit outputs a ?1 signal and a ? component signal, the ?1 signal corresponding to the signal prior to ?1 differential detection and the ? component signal being a combination of ?2 through ?4. A ?1 demodulation unit subjects the ?1 signal to differential detection so as to generate ?1. A second phase error detection unit 56 detects a phase error in accordance with an output signal from the ?1 demodulation unit.

Abstract: Transmitting non-polluting dummy pilot signals in a wireless communication network permits estimation of the downlink propagation channels between a number of joint transmitters and a lesser number of receivers. With fewer receivers than transmitters, loop back information from the receivers is not sufficient to determine the downlink propagation channels between the transmitters and receivers. For N transmitters and M receivers, (N-M) dummy pilot symbols are transmitted to facilitate downlink channel estimation. Each dummy pilot signal is transmitted to an imagined or dummy receiver that is virtually located such that its downlink channel coefficient vector is orthogonal to those of the real receivers. Transmit pre-filtering based on estimated propagation channels is applied to the information signals for the real receivers and to the dummy pilot signals. The extent to which the dummy pilot signals interfere at each receiver is an indication of mismatch between estimated and actual propagation channels.

Abstract: An algorithm identifies a line-of-sight (LOS) signal that may be used to provide an effective time-of-arrival (TOA) estimation.

Abstract: The invention relates to a method for estimating a delay of a signal received at a mobile station MS from a specific network element BS1, BS2 of a network for determining the location of the mobile station. In order to reduce the false alarm ratio and to increase the acquisition probability, it is proposed that the method comprises estimating the delay within a search window. The search window is determined based on location information available for the specific network element BS1, BS2 and on a known distance of the mobile station MS to at least one other network element BS0, BS1. The invention relates equally to a corresponding mobile station MS, to a corresponding network element BS0, and to a communication system comprising at least one mobile station and at least two network elements.

Abstract: A method and apparatus for correcting for Doppler shift in GSM signals at a mobile handset in communication with a base station is provided. The rate of change of position of the mobile unit is detected in relation to the base station and a Doppler correction is derived from the rate of change. This can be used when calculating the synchronization of the UMTS timebase from the GSM network information.

Abstract: An apparatus for testing the phase linearity of a network comprises a first local oscillator, a first mixer, and a first filter, a second local oscillator, and a second mixer for mixing the first IF to the desired output frequency. The output of the second mixer is coupled to a second filter which passes the desired frequency band, but rejects the high frequency mixing harmonics produced in the second mixer. The output of the second filter is coupled to a variable gain amplifier capable of amplifying the frequency band of interest to the desired level and a third filter which further rejects unwanted high frequencies in the output.

Abstract: Phase and amplitude deviations, which are generated, for example, by cables connecting an array antenna of a CDMA base station and the base station, are calibrated in the baseband.

Abstract: A cellphone system comprises a GPS reference station located with a telephone cell site. Such GPS reference station tracks the GPS satellites visible to its local area and estimates the Doppler for each such GPS satellite. The system also includes mobile GPS receivers and cellphones that move around and through the operational area of the cell site. It is assumed that the satellite Dopplers seen by the GPS reference station will have insubstantial differences with the true Dopplers observed by other GPS receivers operating within the cell site's service area. The Doppler estimates are thus routinely communicated over a wireless telephone channel to the mobile GPS receivers and cellphones that register locally. Such mobile GPS receivers then can confidently adopt the surrogate Doppler estimates as a center starting point for their initialization frequency searches. The time required for such mobile GPS receivers and cellphones to initialize and provide a first fix is thereby substantially reduced.

Abstract: A system and method for applying an algorithm to distance measurements between nodes in an ad-hoc communications network (100). The algorithm is located at an individual node (102, 106, 107) of the ad-hoc network (100) and processes collected data via a multi-path filter to ensure that range measurement data is correct, and if so, include such measurement data in a historical data matrix in which old measurement data is eliminated. During periods where received signals are unable to provide correct distance measurements due to reflections affecting the path between nodes or media absorption or radio energy, distance estimates may be obtained from this accurate historical data.

Abstract: Interference within a wireless apparatus is mitigated by adjusting one or more transmission characteristics associated with an interconnect of the apparatus. In at least one embodiment, the interconnect is a PCI Express interconnect.

Abstract: An OFDM transceiver has a transmitter, a receiver, and a loopback switch. The loopback switch configured is for selectively establishing a physical connection between an output terminal of the transmitter and an input terminal of the receiver. The transmitter is configured for outputting to the output terminal an OFDM signal generated based on a local oscillator signal. The receiver is configured for demodulating the OFDM signal, received via the physical connection, using the local oscillator signal and determining amplitude and phase imbalance parameters based on performing frequency-domain estimation of amplitude and phase imbalances. Hence, the receiver is configured for performing imbalance compensation on a received wireless OFDM signal based on the determined amplitude and phase imbalance parameters. Hence, amplitude and phase imbalances can be estimated accurately despite channel fading and frequency variations encountered between the transmitter of the wireless OFDM signal and the receiver.

Abstract: The amplitude and phase errors of the modulation and demodulation in a transceiver are corrected by a self-calibration procedure in which a test signal is applied to the baseband input of the transmitter, and the output of the modulator is looped back to the input of the demodulator. The amplitude and phase errors of the resulting signal at the baseband output of the receiver are detected, and the contributions of the transmitter and receiver to the errors are separated and resolved into amplitude and phase components. Adjustments are then made to the amplitude and phase balance in the transmit and receive signal paths to correct the errors.

Abstract: Methods for determining delay offsets of communication systems are provided. One such method comprises: determining components of a propagation path of a base station of a communication network; determining a propagation delay associated with each of the components; and determining a delay of the propagation path using the delays of the components. Systems also are provided.

Abstract: The invention relates to a method of estimating a downlink channel in a radio system, and user equipment in a radio system. The user equipment is configured to form an impulse response for a common pilot channel transmitted with a wide antenna beam and an impulse response for a beam-specific pilot signal transmitted with a directional narrow antenna beam. The user equipment is further configured to calculate the impulse response of the downlink channel by using the impulse response of the common pilot channel and the impulse response of the beam-specific pilot signal, taking into account the phase difference formed.

Abstract: Disclosed is a method for estimating a Doppler frequency with phase information, thereby estimating a maximum Doppler frequency. The method for estimating the Doppler frequency includes the steps of measuring phases of phase samples from a plurality of slots of a received signal, evaluating a phase difference of the measured phase, and estimating a maximum Doppler frequency according to a mean of at least one phase difference.

Abstract: An antenna array beamforming technique employs independent transmit weighting coefficients for multiple subscriber units served by a transmitting communication device. Optimization of the weighting coefficients is a joint, rather than an independent, venture of the multiple subscriber units. Joint optimization preferably is implemented at the transmitting communication device and involves the communication device optimizing based on knowledge of the channels between itself and each of the subscriber units, as well as knowledge of the inter-cell and intra-cell interference observed at each of the subscriber units. Joint optimization of the weighting coefficients is a complex process, and to simplify the process optimization criteria are defined that allow the weighting coefficients corresponding to the subscriber units to be optimized independendy rather than jointly.

Abstract: A test signal generator at a transmitter station and a facsimile generator at a receiver station go through an acquisition and tracking process which aligns the two signals so that a logical processor can compute the frequency transfer function of the entire propagation path for use in an adaptive, concurrently sent communication signal. The frequency transfer function is conveyed back to the transmit end via a control channel permitting an adaptivity function at the transmit end to influence subsequent selection of communication parameters, among which are typically transmitted data rate, selection of modulation, selection of forward error correcting coding, and selection of frequency band for transmission. The same measurement is conveyed to an adaptivity function at the receive end for use in the communications receiver to select demodulator variables such as gain control, and equalization of amplitude and phase, versus frequency.

Abstract: A method and system for distance measurement in a low or zero intermediate frequency (IF) half-duplex communications loop measures the distance between two transceivers without synchronizing the local oscillators of the two transceivers. Transceiver distance may be measured in systems that use direct conversion (zero IF) or intermediate frequencies that are so low that phase noise significantly reduces the accuracy of the distance measurement. The communications loop demodulates, re-modulates and retransmits a received signal to provide a re-transmitted signal that has the same carrier and modulation frequency as the received signal. A phase-hold circuit provides an analog system for half-duplex operation that retains the frequency and phase information of the received signal for retransmission in a subsequent time slot.

Abstract: This invention relates to a wireless LAN access point including a communication unit capable of communication by the first wireless communication method, a unit which detects that the traffic density in the communication band used by the first wireless communication method exceeds a predetermined traffic density, and a unit which limits the traffic density in the communication band of the first wireless communication method by a wireless LAN client when the traffic density is detected to exceed the predetermined traffic density.

Abstract: Determination of a received signal strength indication in a direct conversion receiver begins by determining, at a given time, a 1st value to be the larger of the in-phase component of the received signal and the quadrature component of the received signal. The direct conversion receiver then determines a 2nd value at the given time to be the smaller of the in-phase component of the received signal and the quadrature component of the received signal. As such, at a given time, the 1st and 2nd values correspond to the greater and lesser of the in-phase component and quadrature component, respectively. Having obtained these values, the direct conversion receiver then determines the received signal strength indication based on the 1st value, the 2nd value and an offset value. The offset value provides a scaling of the RSSI value based on the range of the RSSI values.

Abstract: A method of forming directional antenna beams, comprising: directing at least two antenna beam signals by means of a beam formation matrix and pre-phasing pre-determined antenna beam signals formed with an antenna array in such a way that the signal of at least one antenna beam has a different phase compared with the signals of other antenna beams. The pre-phasing is implemented with a pre-phasing element, which comprises phasing coefficients in digital implementation. The pre-phasing element is implemented in such a way, for example, that the power of the sum signal of the antenna elements is evenly distributed to the different antenna elements in a pre-determined variation range.

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: Disclosed is a method for simplifying a signal processing process of a base station that receives signals through four branches using two two-branch polarized antennas for each sector. The base station receives signals through first and second branches of the first polarized antenna and third and fourth branches of the second polarized antenna, time-delays the signals received at the second and fourth branches so as to distinguish an offset thereof from an offset of the signals received at the first and third branches, adds the signal received at the first branch and the signal received at the second branch and time-delayed, and adds the signal received at the third branch and the signal received at the fourth branch and time delayed. A modem processor separates an offset distinguishable signal from the added signals.

Abstract: The invention discloses a method that identifies whether a channel is LOS or NLOS in a mobile communication system. After coherent accumulation and non-coherent accumulation have been made by the system, first the method takes power difference between the direct path and the non-direct path in a same power delay profile to identify a channel; and then the result is further determined by {overscore (?)}/? difference of a LOS channel and a NLOS channel (where {overscore (?)} and ? is the mean delay and the RMS delay spread of a multipath power profile, respectively). A channel is determined as a LOS channel, if the power ratio of the Maximum Path to the Local Maximum Path is greater than a threshold K, and simultaneously the arrival time difference between the First Path and said Maximum Path is less than a time interval T; otherwise it is a NLOS channel. The method is easier to implement and compatible with the present mobile communication system.

Abstract: Signals including a plurality of components representing a phase rotation between antenna elements by combining signals, which have arrived through each path of a first to an m-th paths, for every antenna are generated in RAKE combining sections 104-1 to 104-n; one angle spectrum is obtained in one direction-of-arrival estimation section 105 provided in each communication terminal, using the signals generated in the RAKE combining sections 104-1 to 104-n; and a plurality of directions-of-arrival are estimated en bloc by detecting a plurality of peak positions on the angle spectrum.

Abstract: An automatic frequency correction (AFC) apparatus used for CDMA multipath fading channels comprises a frequency-offset evaluator, an automatic frequency correction loop filter and a carrier frequency adjuster. The present invention provides a “multipath energy window” designing method for the non-determinacy of multipath signals in mobile communication environment. Frequency-offset information can be extracted from the multipath energy window by a simple calculation and evaluated by a maximal SNR weight process. This invention also provides a step-variable accumulation adjusting method and greatly improves the response speed of the AFC apparatus as compared with a conventional loop filter, whereby supplies better AFC required for CDMA mobile terminals.

Abstract: A signal strength compensation unit for mobile radio receivers is connected upstream of the channel estimator and the channel equalizer and compensates for, in particular, the great, brief signal strength fluctuations within a data burst. Likewise, a method for signal strength compensation compensates for brief signal strength fluctuations within the data burst. To these ends, a signal strength average is determined from the signal strengths for the previously received data symbols. The current signal is then aligned with this signal strength average. The inventive signal strength compensation allows the bit error rate during data equalization to be significantly reduced.

Abstract: Disclosed are systems and methods which proactively determine particular access terminals which are compatible for simultaneous communication at a high data rate and preferred embodiments provide scheduling of simultaneous communications such that data communication is optimized. Preferred embodiments of the present invention utilize a multiple element antenna array, and associated array response vectors associated with narrow antenna beam forming techniques, (adaptive array antennas) to identify compatible access terminals, such as by calculating a correlation between particular access terminals and, preferably utilizing a predetermined correlation threshold, identifying suitably uncorrelated access terminals. Using such information embodiments of the present invention may determine which particular access terminals may be controlled to transmit at a high data rate at a same time. Embodiments of the present invention are operable with respect to the forward and/or reverse links.

Abstract: An improvement for a phasor fragmentation engine and method, whereby a phasor flipping algorithm is applied when determining fragment phasors for a non-constant envelope modulation signal (e.g. OFDM). The phasor flipping algorithm avoids sharp phase transitions for the fragment phasors, which cause an increase in bandwidth, by performing a comparison of the phasor angle separation between the prior and current time samples. This comparison corresponds to a determination of whether the modulation signal V has passed near or through zero.

Abstract: A mobile communication apparatus with an antenna array and a mobile communication method therefore, wherein the apparatus includes a base station with an antenna array and a mobile station, wherein the mobile station determines a channel downlink characteristic for each antenna, determines long-term information and short-term information, converts the determined long-term information and short-term information to a feedback signal, and transmits the feedback signal to the base station. The base station receives the feedback signal, extracts a plurality of weights from the long-term information and short-term information, multiplies a multiplexed dedicated physical channel signal by the respective weights, adds respective pilot channel signals to the products, and transmits the results of the additions through the antenna array to the mobile station.

Abstract: A system and method for providing adaptive threshold selection for detecting a signal in the presence of interference or noise. The system and method thus enables a node, such as a mobile user terminal, in an ad-hoc communications network to reduce the number of false alarms it experiences in the detection of communications signals due to, for example, sudden noise bursts or reception of a high powered signal that overloads the automatic gain control (AGC) device of the receiver in the node. The system and method employ two correlation circuits which correlate the received signal with two reference sequences and output a correlated signal, a threshold generating circuit which generates a threshold value based on the estimation of the variance of the output of the first correlation circuit, and a comparison circuit which compares the correlated signal to the threshold value to determine whether the received signal includes a valid data signal, as opposed to only noise.