1243results about "Equalisers" patented technology

A intelligent backhaul radio have an advanced antenna system for use in PTP or PMP topologies. The antenna system provides a significant diversity benefit. Antenna configurations are disclosed that provide for increased transmitter to receiver isolation, adaptive polarization and MIMO transmission equalization. Adaptive optimization of transmission parameters based upon side information provided in the form of metric feedback from a far end receiver utilizing the antenna system is also disclosed.

A intelligent backhaul radio is disclosed that is compact, light and low power for street level mounting, operates at 100 Mb / s or higher at ranges of 300 m or longer in obstructed LOS conditions with low latencies of 5 ms or less, can support PTP and PMP topologies, uses radio spectrum resources efficiently and does not require precise physical antenna alignment.

A system for monitoring the output of an adaptive channel equalizer in order to determine if convergence has been achieved. A slicer samples data from the equalizer during a predetermined period. The output data from the slicer is forwarded to a microprocessor in order to apply a test standard to the slicer data. For example, if one of every possible transmitted symbol is detected by the microprocessor, convergence is assumed to have occurred. If the test criterion is not met, a reset signal is sent to the equalizer.

In accordance with the teachings described herein, systems and methods are provided for a precision adaptive equalizer. A variable gain equalizer may be used to apply a variable gain to an input signal to generate an equalized output signal. A phase and pattern detector circuit may be coupled in a feedback loop with the variable gain equalizer. The phase and pattern detector circuit may be used to identify a high frequency data pattern in the equalized output signal and compare the high frequency data pattern with a clock signal to detect a high frequency phase error. The phase and pattern detector circuit may be further operable to generate an automatic gain control signal as a function of the high frequency phase error, the automatic gain control signal being fed back to the variable gain equalizer to control the variable gain applied to the input signal.

Modulation Demodulation (Modem) Format Selectable (MFS) and Code Selectable (CS) systems for new generations of wireless systems, including third generation “3G”, spread spectrum systems, CDMA,W-CDMA and GSM, OFDM systems having different bit rates, that is having bit rate selection or bit rate agile( BRA) operation. MFS and Code Selectable (CS) systems connected to one or more modulators, one or more transmit amplifiers and one or more antennas. The transmitted signals are received by single or multiple receivers and demodulators.Shaped Time Constrained Signal(TCS) wavelet processors and bit rate agile Long Response (LR) filters provide shaped Time Constrained Signal (TCS) waveforms / filtered signals in in-phase(I) and quadrature-phase(Q) baseband channels to one or more Quadrature Modulators(QM) connected to the baseband signal processing network. A control processor and signal selection device selects one or more of the baseband signals and provides these signals through one or more quadrature modulators(QM) having the same or different radio frequency(RF) signals for amplification by one or more amplifiers. A selection device for selecting a Linearly and / or a Non-Linearly Amplified (NLA) modulated signal is provided and the selected amplified signal is provided to one or more transmit antenna systems or to one or more transmission media.

Spread Spectrum baseband signals, in-phase and quadrature-phase cross-correlated baseband signals and other filtered baseband signals connected to modulators for providing modulated signals. Modulator selection for modulated signal selection or for multiple modulated signals provided to one or more antennas for signal transmission.

A communication system and method for extending coverage of a base transceiver station. The communication system includes processing circuitry that receives a communication signal over a wireless channel. The received communication signal is processed through an adaptable equalizer to reduce noise, distortion, interference, and frequency errors. In another aspect of the invention, a frequency of a reference signal in the communication system is adjusted to compensate for frequency errors between the communication system and the source of the communication signal. The equalized and frequency adjusted communication signal is then retransmitted into an extended coverage area. Wireless coverage is thereby provided between a base transceiver station and a mobile device in the extended coverage area.

For radio communications between a base station and a mobile station, resource allocation within a resource block including control resources used for control signals (CQI, ACK / NACK) and reference resources used for a reference signal is performed. The base station measures the quality of a channel between the mobile station and the base station itself. Based on the measured channel quality, the base station sets a ratio between resources for the control signals CQI and ACK / NACK in the control resources, and notifies the mobile station of the set resource ratio.

A wireless local area network (WLAN) communicatively couples together a group of mobile wireless terminals configured to operate in a wireless wide area network (WWAN). A network-management operator processes WWAN-control messages used by the mobile wireless terminals and the WWAN. One or more of the mobile wireless terminals may function as the network-management operator.

For digital data transmitted using a vector signaling encoding, a rank-order equalizer cancels various channel noise such as inter-symbol interference. Further, rank-order units may be cascaded to achieve improved equalization over successive sample vector signals in a rank-order equalizer. Multiple rank-order equalizers further operate in parallel in a feed forward mode or in series in a feedback mode to provide a continuous vector signaling stream equalization.

A system and methodology for channel equalization are provided. According to one aspect, a receiver structure for a MIMO system is provided that employs frequency domain equalization (FDE) with noise prediction (FDE-NP). The FDE-NP structure may include a feedforward linear frequency domain equalizer and a group of time domain noise predictors (NPs), which may operate by predicting a distortion corresponding to a given linearly equalized data stream based on previous distortions of all linearly equalized data streams. According to another aspect, a receiver structure for a MIMO system is provided that employs FDE-NP with successive interference cancellation (FDE-NP-SIC), which can extend the functionality of FDE-NP by ordering all linearly equalized data streams according to their minimum mean square errors (MMSEs) and detecting those streams which have a low MMSE first, thereby allowing current decisions of lower-indexed streams to be considered along with previous decisions for all data streams for noise prediction. According to a third aspect, a method for analyzing the performance of a MIMO system with equalization is provided. Pursuant to the method, a general expression of MMSE may first be derived. The MMSE expression may then be related to an error bound by applying the modified Chernoff bounding methodology in a general MIMO system. The parameters in the result may then be varied for applicability to single-input single-output (SISO), multiple-input single-output (MISO), and single-input multiple-output (SIMO) systems with receiver equalization technology.

One of sequence groups each specifying reference signal sequences for respective radio resource bandwidths is assigned to a base station and a different one of the sequence groups is assigned to a neighboring cell. The base station includes a scheduler configured to allocate radio resources; a reporting unit configured to report the allocated radio resources and a cyclic shift amount to a mobile station; and a demodulating unit configured to demodulate a signal received from the mobile station based on one of the reference signal sequences corresponding to one of the radio resource bandwidths and the cyclic shift amount. Cell reuse is applied to the reference signal sequences to be transmitted using one resource unit, and sequence hopping where different ones of the reference signal sequences are assigned to consecutive subframes is applied to the reference signal sequences to be transmitted using a bandwidth greater than one resource unit.

A method for carrying out channel equalization in a radio receiver wherein an impulse response is estimated, noise power is determined by estimating a co-variance matrix of the noise contained in a received signal before prefiltering, and tap coefficients of prefilters and an equalizer are calculated. The method comprises determining the noise power after prefiltering by estimating a noise covariance matrix, after which input signals of the channel equalizer are weighted by weighting coefficients obtained from the noise covariance estimation.

A radio frequency receiver subject to a large in-band interferor employs active cancellation with coarse and fine cancellation signals, each with a respective radio frequency combiner, in order to increase the effective dynamic range of the receiver for weak signals of interest. One or both can be digitally synthesized. This is particularly applicable for co-site interference, whereby the interfering transmit signal is directly accessible. A similar system and method may also be applied to external interferors such as those produced by deliberate or unintentional jamming signals, or by strong multipath signals. An adaptive algorithm may be used for dynamic delay and gain matching. In a preferred embodiment, a hybrid technology hybrid temperature system incorporates both superconducting and semiconducting components to achieve enhanced broadband performance.

A method and transceiver for wireless multicarrier communications. At the transmitter side, conventional OFDM symbols, after inverse fast Fourier Transform, are scrambled in time domain and then guard-interval (GI) inserted, up-converted at the carrier frequency for transmission. At the receiver side, after GI removal and frequency domain channel equalization, the received signal is transformed into time-domain by inverse fast Fourier Transform. The time-domain equalized signal is descrambled in time domain and then transformed back to the frequency domain before it is rate-matched, demodulated and decoded. This time-domain scrambling and descrambling method can be used in a wireless OFDM system such as WLAN, cellular OFDM, and MC-CDMA.

Method and process for receiving, demodulating, equalizing and processing of Modulation Demodulation Format Selectable (MFS) received signal, received from two or more than two antennas and from diversity receivers. Baseband processing filtering and adaptively equalizing demodulated signals and providing filtered equalized burst operated Time Division Multiplexed (TDM) cross-correlated in-phase and quadrature phase signal, spread spectrum Code Division Multiple Access (CDMA) signal and Orthogonal Frequency Division Multiplexed (OFDM) signals. Demodulation of peak limited cross-correlated OFDM signals. Demodulation and adaptive equalization of receive filtered signal, wherein the received filtered signal is mis-matched to transmit filtered signal. Process for receiving and demodulating MFS signals received from modulated linearly amplified and transmit filtered modulated non-linearly amplified (NLA) signal transmitters. Demodulation and processing of cross-correlated TDM, spread, spectrum and OFDM signals.

A method for an adaptive equalization apparatus in a multiple-link hopping radio system includes hopping among a plurality of radio links to receive variable-length bursts of radio signals on the plurality of radio links and equalizing amplitude and phase variations of a slow channel for each radio link from a received burst on the radio link. Further, the method includes storing the estimated tap coefficients pertinent to each radio link and using the tap weights of the current burst of the radio link to reliably pre-compensate the channel amplitude and phase distortion of a next received burst on the radio link.

An adaptive equalizer system for use in a serial communication link uses timing information generated by a phase detector of a clock and data recovery circuit of the serial communication link and a frequency pattern of the recovered data to determine whether the data received over the serial communication link is over-equalized or under-equalized. The equalizer strength of the adaptive equalizer system is adjusted based on such determination.

A conventional power amplifying device has a problem that when a signal band is widened, sampling frequency for distortion detection is increased and an FFT calculation amount of a distortion compensation unit is increased, which increase a circuit size and power consumption. The present invention provides a non-linear distortion detection method and a distortion compensation amplifying device capable of suppressing increase of the circuit size and the power consumption even if the signal band is widened. A signal obtained by feeding back an output of a power amplifier is sampled by an A / D converter. An equalizer of a distortion detection unit uses an input signal d(n) of a predistorter as a reference symbol to detect an equalization error e(n) of the orthogonal demodulation signal u(n). An absolute value averaging unit outputs an absolute value of the equalization error e(n) which has been temporally averaged to E(n) as a distortion value to a control unit. According to the distortion value, the control unit adaptively controls the predistorter to perform distortion compensation.

The invention relates to a method and an arrangement intended for radio communication systems and effective in digitalizing and subsequently processing numerically arbitrary radio signals. The signals are represented by composite (complex) vectors which have been subjected to disturbances in the system, such that information in the signals has been lost. This information is restored in its entirety when practising the present invention. For the purpose of solving this problem, the inventive digitalizing arrangement includes a multistage logarithmic amplifier chain (A) in which each stage is connected to a separate detector (D), the output signals of which are added in an adder. The adder output signals are then transmitted to a first A / D-converter (AD1) for digitalizing and converting the amplitude components of the signal. At the same time, the undetected signal from the saturated output stage in the amplifier chain is transmitted to a second A / D-converter for digitalizing and converting the phase components of the signal. The digital values obtained on the outputs of the AD-converters (AD1, AD2) are applied to different inputs of a digital signal processor (MP) for numerical processing of the pairwise received digital values in a manner such as to restore the complete vector characteristic of the signal.

Various embodiments of the present invention provide systems and methods for selecting between pre-coding and non-pre-coding. As an example, a data processing circuit is disclosed that includes: a first data detector circuit, a second data detector circuit, a first comparator circuit, a second comparator circuit, and a pre-code selection circuit. The first data detector circuit is selectably configurable to operate in a pre-coded state, and operable to apply a data detection algorithm on a data input to yield a first detected output. The second data detector circuit operable to apply the data detection algorithm to the data input to yield a second detected output without compensating for pre-coding. The first comparator circuit operable to compare the first detected output against a known input to yield a first comparison value, and the second comparator circuit operable to compare the second detected output against the known input to yield a second comparison value. The pre-code selection circuit is operable to determine a selectable configuration of the first data detector circuit based at least in part on the first comparison value and the second comparison value.

In a radio communication system, each of user terminals together with transmitting a data signal to a base station using different data transmission band frequencies that are assigned by a base station, performs time-division multiplexing of a pilot signal with the data signal and transmit the resulting signal to the base station. A resource management unit of the base station decides pilot transmission bands for each user terminal so that the pilot transmission band covers the data transmission band for each user terminal by frequency offset, and instructs the user terminal to transmit pilot signals using the decided pilot transmission band frequencies. Thereby the base station can estimate channel for each frequency of the data transmission band using the pilot signal.

An RF transmitter (10) includes a linear predistorter (22) and a nonlinear predistorter (24) which together drive analog transmitter components (14). The linear and nonlinear predistorters (22, 24) are implemented using a collection of adaptive equalizers (30). A feedback signal (20) is developed by downconverting an RF communication signal (16) obtained from the analog components (14). The feedback signal (20) are used in driving tap coefficients (34) for the adaptive equalizers (30′, 30″) in the nonlinear predistorter (24). An intermodulation-product canceller (94) uses signal cancellation to cancel intermodulation products from the feedback signal (20) and generate an intermodulation-neutralized feedback signal (96). The intermodulation-neutralized feedback signal (96) is used along with a modulated convergence factor (43) in driving tap coefficients (34) for the adaptive equalizer (30) in the linear predistorter (22).

Various embodiments of the present invention provide systems and methods for data processing. As an example, a data processing circuit is disclosed that includes an equalizer circuit and a data detection circuit. The equalizer circuit is operable to filter a series of samples based at least in part on a filter coefficient and to provide a corresponding series of filtered samples. The data detection circuit includes: a core data detector circuit and a coefficient determination circuit. The core data detector circuit is operable to perform a data detection process on the series of filtered samples and to provide a most likely path and a next most likely path. The coefficient determination circuit operable to update the filter coefficient based at least in part on the most likely path and the next most likely path.

Transmitter apparatus to broadcast coded orthogonal frequency-division multiplexed (COFDM) radio-frequency carriers conveying digital television (DTV) signals encoded using Bose-Chaudhuri-Hocquenghem (BCH) coding concatenated with subsequent low-density parity-check coding (LPDC) transmits the same coded DTV signals twice some time apart. The coded DTV signals are mapped to quadrature amplitude modulation (QAM) of the COFDM carriers. Preferably, the circular Fourier transforms of COFDM symbols in the earlier transmissions are rotated one half revolution respective to the circular Fourier transforms of corresponding COFDM symbols in the later transmissions. Receiver apparatus combines the earlier and later transmissions of twice-transmitted COFDM signals as part of iterative procedures for de-mapping QAM and decoding the concatenated BCH-LDPC coding of the DTV signals.