Abstract: There is provided a system and method of transmitting wireless data. The data signal has a multipath effected upon it and the effected multipath is used to decode the received signal. This is achieved by either passing the signal through a multipath filter prior to transmission or by producing a plurality of reflections of the transmitted signal. In the receiving end, the multipath selector will choose a preferred multipath profile and then form the data vectors for further processing. Systems for multiple input multiple output (MIMO) are thereby possible with fewer receiving antennas than transmitting antennas. Also orthogonal frequency division multiples (OFDM) systems are possible in multipath environments. Combining of beam-forming and MIMO and OFDM systems is also enabled.

Abstract: Communication signal equalization methods and systems are disclosed. A CDMA signal having a data portion and a known portion including a known or repeated data sequence and received over a multipath communication channel represents a linear convolution between the multipath channel and a transmitted CDMA signal. A channel estimate of the communication channel is determined from the known portion, and the CDMA signal is translated into a new CDMA signal which is a cyclic convolution with the channel estimate. A frequency domain representation of the new CDMA signal is adjusted using the channel estimate to produce a frequency domain representation of an equalized signal.

Abstract: A receiver comprising: an antenna which receives a radio signal including N possible symbols {c1(n), c2(n), . . . cM?1(n), cM(n)}, an N correlation units which are provided corresponding to the N possible symbols, respectively, each correlation unit detecting the degree of correlation with the radio signal received by the antenna, and a symbol determination unit which determines the symbol included in the radio signal received by the antenna based on the degree of correlation detected by the N correlation units. The N correlation units detect the degree of correlation between the radio signal received by the antenna and the N possible symbols represented by M chips {?0c1(n), ?0c2(n)+?1c1(n), . . . , ?0cM?1(n)+?1cM?2(n), ?0cM(n)+?1cM?1(n)}.

Abstract: The N peaks are selected from a delay profile in order starting from the highest peak involved in the delay profile, the path level and path timing are determined for each of the selected peaks, and the identical paths individually responsible for different delay profiles are detected by comparing the path timings calculated for the preceding time and the path timings calculated for the present time. Based of the path levels calculated for the preceding time and the path levels calculated for the present time, averaged path levels are computed on a path-by-path basis for the present time, a predetermined threshold is applied to the computed average path levels, and the paths to be allocated to the fingers are selected. Of the path timings that have been obtained for respective selected paths, the latest path timings are allocated to the fingers as synchronization timings.

Abstract: Blind or partially blind process to determine characteristic space-time parameters of a propagation channel in a system comprising at least one reception sensor receiving a signal y(t). It comprises at least one step in which the specular type structure of the channel is used and a step for the joint determination of parameters such as antenna vectors (a) and/or time vectors (?) starting from second order statistics of the received signals. Application for monitoring the spectrum of a propagation channel for positioning purposes starting from one or several HF stations or for standard communication links with equalization or positioning or spatial filtering.

Abstract: An antenna system (205) includes an antenna structure (215), a receiver (220), and an antenna system controller (225). The antenna structure includes an arrangement of antennas (237), a signal combiner (240), and a switching matrix (235). The arrangement of antennas is designed to have a set of antenna element separations that are optimized to provide lowest correlation coefficients of intercepted radio signals for a corresponding set of electromagnetic environment types that vary from a very low density scattering environment to a maximum density scattering environment. The antennas (230), (231), (232), (233), (234) in the antenna arrangement each include at least one element that has a common polarization. There is at least one antenna that is a dual polarized antenna. The antenna system selects an antenna element pair that corresponds to the environment type which it is operating and thereby receives a best combined signal.

Abstract: A diversity receiver (60) has two diverse channels fed by the antennas, an adaptive equalizer (20,30) for each channel and a coefficient adapter (40) for adapting two sets of coefficients in a time shared manner for the equalizers. A combiner combines the equalized signals. By sharing one adapter for adapting the coefficients between two or more equalizers, the calculation load can be reduced. This is useful for small mobile terminals powered by battery, for use with GSM or UMTS or other radio networks. It can be applied to any type of equalizer, and using any manner of time sharing. The combiner can exploit any type of diversity between the equalized signals. The equalizers can output two equalized signal values in consecutive time slots, by reusing the same coefficients, while new coefficients are being calculated.

Abstract: A reception quality reporting system may include a communication terminal that measures reception directivity quality in a quality decision signal received from a base station apparatus. The communication terminal decides a switching timing at which directivities of packet data are switched based on directivity switching timing information communicated by the base station and nullifies the reception quality measured in a period before the switching timing. The communication terminal transmits to the base station apparatus reception quality information indicating the measured reception quality.

Abstract: A wireless communication system and method for controlling transmission power to maintain a received signal-to-interference ratio (SIR) as close as possible to a target SIR. A received quality is maintained as close as possible to a target quality based on block error rate (BLER). When a target BLER is converted to an initial target SIR, an error may occur due to a channel condition mismatch, since the target SIR required for the target BLER varies with channel conditions. An outer loop power control process is used to set a target SIR for each coded composite transport channel (CCTrCH) based on the required target BLER. The process adjusts a SIR step size parameter to maximize the convergence speed of the process.

Abstract: A data transmitting/receiving apparatus and method using an antenna array in a mobile communication system. A Node B measures a transmission status of each transmission antenna, classifies transmission data according to priority, and transmits to a UE high-priority data through a transmission antenna at a relatively good transmission status and low-priority data through a transmission antenna at a relatively poor transmission status.

Abstract: A method of quadrature amplitude modulation involving encoding phase differentially and amplitude absolutely, allowing for a high data rate and spectral efficiency in data transmission and other communication applications, and allowing for amplitude scaling to facilitate data recovery; amplitude scale tracking to track-out rapid and severe scale variations and facilitate successful demodulation and data retrieval; 2N power carrier recovery; incoherent demodulation where coherent carrier recovery is not possible or practical due to signal degradation; coherent demodulation; multipath equalization to equalize frequency dependent multipath; and demodulation filtering.

Abstract: A method for initial downlink transmit power adjustment for non-real time services in a wireless communications network begins by estimating an initial downlink transmit power level for non-real-time services. The estimated power level is then compared with a threshold. A determination is made whether an increase in the estimated power level would affect neighboring cells. If an increase would not affect neighboring cells, then the initial downlink transmit power level is adjusted by a predetermined amount.

Abstract: The present invention is an assigning system and method for assigning a plurality of rake finger tracking units of a rake receiver in a Code Division Multiple Access (CDMA) communication system. The plurality of rake finger tracking units is used for tracking a plurality of path signal of each multipath signal by a plurality of corresponding predetermined tracking time positions. The assigning system and method estimate a plurality of corresponding tracking ranges of the plurality of path signals and compare the plurality of predetermined tracking time positions with the plurality of tracking ranges. If there is more than one predetermined tracking time positions in one tracking range, the assigning system assigns a rake finger tracking unit corresponding to one of the tracking time positions to track the path signal corresponding to the tracking range.

Abstract: A decorrelating rake receiver (401) using a signal processor (213) and corresponding method (1000) to determine filter coefficients (1005). The decorrelating rake receiver includes a plurality of filters (219) arranged to be coupled to an input signal (403) and the filter coefficients (409), the plurality of filters operable to provide a plurality of output signals and a coefficient generator (407), coupled to the input signal, to explicitly and definitely determine the filter coefficients for the plurality of filters such that the plurality of filters perform a decorrelating rake process. The decorrelating rake receiver further includes a combiner (221) to combine the plurality of output signals and provide a received signal (405). The decorrelating rake receiver (401) is suitable for use in a wireless communication device (101) or base transceiver (103).

Abstract: A desired SIR control part presets the desired SIR value in a way that it decides to this end the degree of follow-up of the desired SIR by the received SIR (measured value), by reading out a desired communication quality value from a demodulating part, reading out a measured communication quantity value from a communication quality measuring part, reading out a desired SIR value from a memory and reading out a measured SIR value from an SIR measuring part. Thus, it is possible to quickly and smoothly cope with the occurrence of a change in the communication environment in the wireless communication in a W-CDMA system or the like between the base station and the mobile station.

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: An adaptive filter for an FM receiver comprises a digital filter, an error detection section for detecting an error between the amplitude of the output signal of the digital filter and a reference value, and a coefficient updating section for updating tap coefficients so as to minimize the error detected. The reference value for determining the error is variably set according to the amplitude of an input signal. This eliminates the effect of Doppler fading included in the reception wave and stabilize the adaptive processing. Thus, the adaptive filter can remove multipath distortion with reliability.

Abstract: A method for increasing data throughput on a wireless local area network in the presence of intermittent interference. The method of one embodiment comprises receiving a data packet through a wireless channel. Quality of the wireless channel is evaluated. A packet error ratio (PER) value is calculated for the data packet. The PER value is checked as to whether it is within an acceptable level. A determination is made as to whether an intermittent noise is affecting the PER value.

Abstract: One preferred embodiment of the invention provides a wireless base station which provides a multicasting service to simultaneously transmit identical data to a plurality of wireless terminals. A wireless base station is connected to a plurality of wireless terminals and provides a multicasting service for a plurality of wireless terminals. The wireless base station determines autonomously whether it provides the multicasting service for the plurality of wireless terminals. Another preferred embodiment of the invention provides a method of selecting a wireless base station for a wireless terminal, the wireless base station providing a multicasting service for the wireless terminal. When the wireless terminal can receive the same multicasting information from a plurality of wireless base stations, the wireless terminal selects one of the plurality of wireless base stations so as to make the number of the wireless base stations that send the same multicasting information as small as possible.

Abstract: A path detection apparatus for use in a CDMA reception device includes: storage means for storing a delay profile; and path detection means for detecting a path by reading the delay profile from the storage means, and performing a rake-combining process based on the read delay profile. With the configuration, the path detection means includes: reference path detection means for detecting a reference path for detection of a probable path based on the delay profile read by the storage means; and detection means for detecting as a probable path in the rake-combining process a path existing in a path detecting time in which reception characteristic of the CDMA reception device can be improved from the detecting time of the reference path detected by the reference path detection means.

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: The invention relates to radio engineering, more specifically to a method and a device for receiving multipath signals in a radio communications system with a code division multiple access (CDMA) and can be used for the receiving equipment of a base station. Said invention makes it possible to compensate a reciprocal signal interference of all user beams of information and pilot channels in a shaped complex cross-correlation response of all user beams of the information and pilot channels. The number of information channels and the data transmission rate in the information channels can vary from user to user. A serial compensation of the reciprocal signals interference of all user beams of the information and pilot channels during measurement of user signal parameters and complex waveform envelopes of all user beams is carried out in several iterations.

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: In some embodiments of the present invention, a signal received by a mobile communication station in standby mode is sampled. The samples are converted to digital samples and stored in a memory. The digital samples include data from a base communication station to the mobile communication station. The stored digital samples are processed.

Abstract: A system and method for enhancing the reception of a single carrier signal. The single carrier signal includes periodic training signal and data. The system includes a transmitter configured such that L symbols of either the beginning or end of the N symbols of the training signal, where L<N, are duplicated at either the end or the beginning of the training signal, respectively. The system further includes a receiver configured to receive the modified training signal for the calculation of FIR coefficients in a single pass and without the need for least mean square (LMS) methods or the like.

Abstract: A signal received under a multipath condition is buffered in storage memories 50a and 50b comprising two banks, and while overlap of write and read is allowed, the received data is supplied to matched filters 60a and 60b as much as possible, in a pipeline manner, and in-phase addition of four symbols per unit is performed in in-phase adders 80a and 80b. In the buffering in storage memories 50a and 50b, processor 40 adaptively changes the search period based on timing information acquired in advance.

Abstract: A path search circuit according to the present invention has an orthogonal multi-beam forming section 4 for directional reception with a plurality of orthogonal multi-beams orthogonal one to another, correlation-operating sections 61–6M for correlation-operating outputs of the orthogonal multi-beam forming section 4 with a known signal, weight multiplying sections 81–8Nb for multiplying the output of the correlation-operating section 61–6M by a weight converted into a beam space, delay profile generating sections 91–9Nb for generating delay profiles from the output signals of the weight multiplying sections 81–8Nb, and a path detecting section 10 for detecting a reception timing and arrival direction of arrival path from the delay profile. This path search circuit can enhance the accuracy of path direction detection by the use of a directional reception signal, and further reduce the direction dependence of path timing detection accuracy.

Abstract: Techniques to acquire and track pilots in a CDMA system. In an aspect, frequency acquisition of a number of signal instances (i.e., multipaths) in a received signal may be achieved concurrently based on a frequency control loop (RAFC) maintained for each finger processor of a rake receiver. Upon successful acquisition, frequency tracking of acquired multipaths may be achieved based on a combination of a frequency control loop (VAFC) maintained for an oscillator used for downconverting the received signal and the RAFCs for the finger processors. In a tracking mode, the VAFC tracks the average frequency of the acquired multipaths by adjusting the frequency of the oscillator. The RAFC of each finger processor tracks the residual frequency error (e.g., due to Doppler frequency shift) of the individual acquired multipath by adjusting the frequency of a complex sinusoidal signal used in a rotator within the finger processor.

Abstract: A system and method are disclosed by which the effects of time of arrival errors may be reduced. In a mobile unit, such as a CDMA device, a correlation pulse is generated when a transmitted code matches a stored reference code. In the absence of multipath effects, correlation pulses are generated in response to the detection of multiple transmissions of the reference code from multiple transmitters. However, multipath effects distort the generated correlation pulses leading to errors in the time of arrival measurements. The present invention calculates the width of the correlation pulses and determines a delay correction factor based on the pulse width. The delay correction factor is added to the measured delay time to provide a more accurate delay time, thus permitting more accurate location measurements based on time of arrival. In alternative embodiments, other signal factors may also be used to apply delay correction factors.

Abstract: A Node-B/base station has a path searcher and at least one antenna for receiving signals from users. The path searcher comprises a set of correlators. Each correlator correlates an inputted user code with an inputted antenna output of the at least one antenna. An antenna controller selectively couples any output of the at least one antenna to an input of each correlator of the set of correlators. A code phase controller selects a user code for input into the set of correlators. Each delay of a series of delays delays the selected user code by a predetermined amount and each correlator of the set of correlators receives a different code phase delay of the selected user code. A sorter and path selector sorts the output energy levels of each correlator of the sets of correlators and produces a path profile for a user based on the sorted output energy levels.

Abstract: A process for estimating a speed of movement of a mobile terminal operating in a wireless communication system and communicating with a base station via a transmission channel includes estimating fading of the transmission channel, and performing an autocorrelation on the fading for providing a first autocorrelation result. Reference autocorrelation results are calculated for predetermined values of speed of movement of the mobile terminal, with the calculating being based upon a known autocorrelation function performed on the fading. The process further includes comparing the first autocorrelation result to the various reference autocorrelation results, and estimating the speed of movement of the mobile terminal based upon the comparison.

Abstract: A base-station transceiver system (BTS) operative in a cellular telephone network, consisting of a main up-link port and a diversity up-link port which are adapted to operate cooperatively to receive up-link signals over-the-air from cellular telephones such that both of the ports receive the up-link signals from each of the cellular telephones. The two ports are coupled to receive signals from wired telephones, such that the main up-link port receives signals only from a first group of the wired telephones and the diversity up-link port receives signals only from a second group of the wired telephones. The system also includes signal processing circuitry which is adapted to receive the signals from the up-link ports and convey the signals over the network.

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: The present invention provides a search window delay tracking procedure for use in a multipath search processor of a CDMA radio receiver. A channel impulse response is estimated for a received signal containing plural paths, each path having a corresponding path delay. A search window defines a delay profile that contains the plural paths of the received signal. A mean or average delay is calculated for the estimated channel impulse response (CIR), and an error is determined between the mean CIR delay and a desired or target delay position of the Cir. search window. An adjustment is made to reduce that error to align the targeted position of the search window and the mean CIR delay. A Doppler frequency is estimated for each path. The adjustment is made taking into account a Doppler effect caused by relative movement between the transmitter and receiver.

Abstract: Wireless communication structures and methods are provided that enhance range and performance via managed access to a wireless communication medium between system clients. The access is configured to maintain the low equipment costs and widespread equipment availability of standards-based communication systems. In particular, the structures include at least one antenna, a processor that spatially processes receive signals from the antenna, a media access controller that compares the age of receive location information with a predetermined time coherence, a location-information transformer that transforms the receive location information into transmit location information, and a transmit spatial processor configured to provide a transmit signal to the antenna that is spatially processed in accordance with the transmit location information if the age is less than the time coherence and spatially processed in accordance with predetermined location information if the age exceeds the time coherence.

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 method for reducing multi-path distortion of an M-ary communication signal is implemented with M×N parallel processors, a multi-path estimator, a metric selector and a decision processor. Parallel processors process each combination of possible signal symbols M and hypothesized guard times N, the output of the processors are supplied to the multi-path estimator which estimates the actual multi-path distortion of the transmitted symbol. The metric selector selects the processors with a guard time Gn most closely approximating the estimate from the multi-path estimator. The selected outputs are used in a decision processor to determine the transmitted symbols. The selected outputs are low passed filtered.

Abstract: A radio system (10) and radio system (1, 2) in which the value of parameters for a model of a received multipath signal transmitted by a remote station (20) are estimated. A sounding signal transmitted and received by the radio station is used to derive data about the reflecting environment and this data is incorporated into the model after scaling it to represent the multipath signal received from a remote station. Optionally or alternatively the remote station may transmit a sounding signal and derive data about its reflecting environment and transmit this data to the radio station, The model may incorporate both sets of derived data, particularly if they are uncorrelated. The values of the resulting parameters are exploited in applications such as ranging, location or equalization.

Abstract: Methods and devices for sending, transmitting and/or receiving information by means of waves, in which an information signal of a carrier wave is impressed, whose frequency is continuously changed to form at least one carrier sweep in a predetermined time interval and in which the information signal is filtered to separate multipath components after being received in the frequency range or is cleaned of noise portions and then evaluated with respect to the information-bearing signal parameters.

Abstract: In mobile communication systems employing the CDMA method, the communication quality is acquired from the CDMA pilot channel. A communication quality acquisition apparatus comprises a delay profile acquisition unit comprising a control unit, synchronization unit and measurement unit, in addition to a data storage unit. The communication quality is measured by the synchronization unit and the measurement unit which are alternatively controlled by the control unit. When the communication quality is acquired through the CDMA pilot channel, the data acquisition efficiency can be significantly raised.

Abstract: In a wireless communications system, a base station employs a bit error rate (BER) based Reverse Outer Loop Power Control (ROLPC) technique. The ROLPC technique uses either instantaneous or weakly filtered values of the BER for comparison with a BER target value for adjusting a target signal-to-noise ratio (SNR). The BER target value is varied as a function of a second order statistic (e.g. variance, standard deviation) of the received SNR. In another embodiment, a symbol error count based ROLPC technique uses adaptive SER targets. In particular, a base station uses a 2nd order statistic, e.g., standard deviation (variance), to identify, or act as a signature of, a particular cellular (wireless) communications environment. The base station monitors the standard deviation of the symbol error count of a received signal (transmitted from a mobile station).

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: A system for reducing multipath interference in a wireless data transmission generally includes a processor and memory device for capturing one or more data packets of the wireless data transmission. The transmitting device associates a time value and/or a spatial value to each of the data packets. Upon capture, the processor determines whether the captured data packet is reflective or non-reflective by comparing the time value or spatial value, as applicable, of the captured data packet to the time value or spatial value of each stored non-reflective packet. The system identifies the captured data packet as non-reflective, if the time value (or spatial value) of the captured packet is different from the time value (or spatial value) of each stored non-reflective packet.

Abstract: Method of obtaining a transmission gain function by means of an array of antennae, a signal to be transmitted by the array being weighted by a vector ({overscore (b)}d) of N complex coefficients, referred to as the transmission weighting vector, N being the number of antennae in the array, the array transmitting to a telecommunication terminal over a transmission channel, referred to as the downlink channel, a downlink transmission signal (Sd) and the said terminal transmitting to the said array over a transmission channel, referred to as the uplink channel, an uplink transmission signal (Su), the said downlink channel being disturbed by an isotropic noise (N?) and/or a directional noise, referred to as the downlink interference (Id), the said transmission weighting vector ({overscore (b)}d) being determined by means of a matrix product from a noise power matrix (Dd) which is a function of the power of the said isotropic noise and/or of the power of the said directional noise and a vector ({overscore (Cd)}),

Abstract: A receiver in a communication system, for combining various significant components of a multipath fading signal and eliminating all other small components, consists of a signal generator, a plurality of delay devices, a plurality of decision feedback equalizers with embedded coherent signal combiners, a controller, a coherent signal combiner, and a decision circuit. The first decision feedback equalizer receives its inputs signals from a delay device and a signal generator, and each of the rest decision feedback equalizer receives its input signals from a corresponding delay device and the signal generator of its previous decision feedback equalizer. The coherent signal combiner, coupled to the output of the summation circuit of the last decision feedback equalizer, combines all the significant component signals together. The decision circuit makes a decision on transmitted symbol from the output signal of the coherent signal combiner.

Abstract: A method (500) and a mobile station (160) for reporting multi-path signals based on a report window are described herein. The mobile station (160) may determine a distribution of a plurality of multi-path signals observed by a receiving unit (220) within the mobile station (160). The mobile station (160) may determine a report window based on the distribution. Based on the report window, the mobile station (160) may report at least one of the plurality of multi-path signals.

Abstract: A system for enhancing the reception of a single carrier signal. The single carrier signal includes periodic training signal and data. The system includes a transmitter configured such that L symbols of either the beginning or end of the N symbols of the training signal, where L<N, are duplicated at either the end or the beginning of the training signal, respectively. The system further includes a receiver configured to receive the modified training signal for the calculation of FIR coefficients in a single pass and without the need for least mean square (LMS) methods or the like.

Abstract: A wireless communication system and method includes antenna arrays at both the transmitter and receiver having a plurality of elements for very high data rate communication. Phased array antennas or directive fixed beam antennas are used with a beamwidth in azimuth and elevation less than 30° to increase the power margin and to decrease the delay spread of signals at the receiver to permit wireless data communications at high data rates in closed environments, for example, bursty transmissions and isochronous communications. The wireless communication system is capable of data transmission rates which exceed 1 Gbps with propagation losses of up to at least 60 dB relative to one meter.

Abstract: A wireless local area network and location system for locating objects within a monitored environment are disclosed. A plurality of access point stations receive and transmit communication signals within a wireless local area network. A processor is operatively connected to each of the access point stations and operative for processing communication signals received from the mobile station and, in one embodiment, determining which communication signals are first-to-arrive signals and conducting differentiation of the first-to-arrive signals to locate a mobile station. Delayed versions of at least one interference signal are weighted and the amplitude and phase controlled with weighted functions W1, W2 . . . Wn. The resultant weighted replicas are summed to determine an approximation of disbursed interference for cancelling interference. The location system can include a tag transmitter and spaced monitoring receivers and processor.

Abstract: A radio station (10) in which the value of parameters for a model of a received multipath signal are estimated, the model comprising a value representative of the perpendicular distance between the plane of the reflecting surfaces (40, 50) and the radio station. This perpendicular distance may be measured from the round trip delay of a sounding signal transmitted by the radio station. The amount of computation is reduced by applying constraints to the parameters, and these constraints may comprise this perpendicular distance. The constraints may also be a function of parameters such as the path length, angle of arrival or amplitude of the direct path signal, and the amplitude of reflections of the sounding signal. The values of the parameters may be estimated initially by analysis of the received signals, followed by a parameter estimation process. The values of the resulting parameters are exploited in applications such as ranging, location or equalisation.