Abstract: Communication processing paths include distortions, such as DC offset in the baseband analog path, local oscillator feed-through distortion, and nonlinearity of gm's and power amplifiers which are calibrated for, separately or in combination. The cascaded DC offset and nonlinear distortions are modeled separately or in combination using even-and-odd order polynomials. A loopback path from the output of one or more distortion causing devices passes through a measurement and calculation module. The calculation module calculates predistortion polynomial's coefficients which will be stored in a look-up table to be used by a baseband predistorter to calibrate the path. The look-up table is stored locally or remotely.

Abstract: In one or more embodiments, a system is provided for communicating between different voltage domains using N+1 capacitive-coupled conductive lines to provide N communication channels. For instance, bi-directional communication (e.g., a first communication in a first direction and a second communication path in the opposite direction) may be provided using three capacitive-coupled signal paths. Two of the signal paths are used as single-ended (i.e., non-differential) signal paths. The third signal path is used to suppress voltage disturbances between two voltage domains.

Abstract: The disclosure can provide methods and systems for autocalibrating a transceiver. The method can include upconverting a bandpass input signal by mixing the bandpass input signal with a first local oscillator signal to form an initial transmitter signal. The initial transmitter signal can be looped back to a receiver and downconverted with a second local oscillator signal having a frequency that is different from the first local oscillator to form an intermediate frequency signal. At least one of a gain and a phase of the transmitter can be adjusted based on a transmitter image sideband of the intermediate frequency signal to generate a calibrated transmitter signal having minimized transmitter image sideband.

Abstract: To assist with the detection of unfiltered device(s), a system observes how the received noise changes between two links as the transmit signal is changed. Harmful unfiltered nonlinear devices will generate significant noise that depends on the transmitted signals; therefore, this additional noise can be quantified to some extent by comparing the observed noise for two different transmit signals. The total noise can be determined from the SNR if the received signal is known. The received signal may be read directly in some non-standard systems, or it may be determined from the known transmit signal and channel attenuation, which is sometimes the case in standard-compliant links, but often with a relatively large error. To circumvent this problem, certain embodiments of this invention only consider the change in noise between two links with the same channel attenuation. This differential comparison makes it unnecessary to accurately know the channel attenuation.

Abstract: Systems and methods are for generating a codebook by: generating a multi-resolution codebook by selecting a common precoder index from a low resolution codebook for a group of adjacent resource blocks (RB)s and for each RB within the group, selecting a high-resolution codebook to fine-tune each RB precoder; and generating feedback for the multi-resolution codebook by quantizing channel state variations.

Abstract: A transceiver in-phase and quadrature (IQ) calibration method is provided. When calibrating the transceiver, an adjusting unit is connected to an output terminal of a transmitter to receive a first radio-frequency (RF) signal. The adjusting unit adjusts a phase delay of the first RF signal to generate a second RF signal to be inputted to an input terminal of a receiver. Through adjusting the phase delay of the first RF signal, both the transmitter and the receiver can be calibrated at the same time.

Abstract: Methods and apparatus are provided for pseudo asynchronous testing of receive paths in serializer/deserializer (SerDes) devices. A SerDes device is tested by applying a source of serial data to a receive path of the SerDes device during a test mode. The receive path substantially aligns to incoming data using a bit clock. A phase is adjusted during the test mode of the bit clock relative to the source of serial data to evaluate the SerDes device. The source of serial data may be, for example, a reference clock used by a phase locked loop to generate the bit clock. The phase of the bit clock can be directly controlled during the test mode, for example, by a test phase control signal, such as a plurality of interpolation codes that are applied to an interpolator that alters a phase of the bit clock.

Abstract: A receiver circuit detects an eye margin within a differential signal having a true component and a complement component. A transmitter circuit adjusts a phase between the true component and the complement component of the differential signal, based on the eye margin, to improve the eye margin. Improving the eye margin results from a reduction in common mode noise within the differential signal.

Abstract: A network communications device is capable of promoting connection quality, and includes: a plurality of transmitting units for outputting a plurality of analog transmit-signals to another network communications device based on a plurality of digital transmit-signals; a plurality of receiving units for outputting a plurality of digital receive-signals based on a plurality of analog receive-signals sent from the another network communications device; an echo canceller for providing a signal for canceling an echo in one of the digital receive-signals; a near end crosstalk canceller for providing a signal for canceling near end crosstalk in one of the digital receive-signals; a decoding circuit for generating a decoded signal based on one of the digital receive-signals subsequent to cancellation of the echo and the near end crosstalk therein; and a power-increasing control circuit for increasing operating power so as to promote connection quality.

Abstract: In at least some embodiments, a communication device includes a transceiver with a physical (PHY) layer. The PHY layer is configured for body area network (BAN) operations in a limited multipath environment based on a constant symbol rate for BAN packet transmissions and based on M-ary PSK, differential M-ary PSK or rotated differential M-ary PSK modulation. The PHY layer is configured to transmit and receive data in a frequency band selected from the group consisting of: 402-405 MHz, 420-450 MHz, 863-870 MHz, 902-928 MHz, 950-956 MHz, 2360-2400 MHz, and 2400-2483.5 MHz.

Abstract: An amplifier is provided. The amplifier includes a pair of first input transistors, a first load, and a first canceling circuit. The pair of first input transistors is coupled between a pair of first differential nodes and a reference voltage source, for receiving a pair of input signals. The first load is coupled to the pair of first differential nodes and a pair of differential output terminals of the amplifier. The first canceling circuit is coupled between the first differential nodes. The canceling circuit is capable of balancing voltages, respectively, at the first differential nodes when the amplifier is turned off.

Abstract: One embodiment of the present invention provides a transceiver for wireless communication. The transceiver includes a transmitting circuit, a receiving circuit, a power amplifier coupled to the transmitting circuit, and a looping mechanism configured to establish a closed loop that couples an output of the power amplifier to an input of the receiving circuit in response to a linearity compensation need, thereby facilitating cost-effective linearity compensation.

Abstract: Disclosed herein are exemplary techniques for power conservation in a wireless network. A wireless device identifies another wireless device suitable to act as a relay node. Uplink information is transmitted to the other wireless device, which is in turn relayed to an access point for transmission to its destination. Downlink information may be transmitted directly from the access point to the wireless device. The use of a relay node may reduce transmit power consumption as the relay node may be closer to, or support a higher transmit rate, than the access point with which the wireless device is associated.

Abstract: Embodiments of the present invention provide an apparatus comprising a transceiver having a receiver and a transmitter connected through a segment of a calibration loop back path. The apparatus also comprises a control system configured to communicate with the transceiver. The calibration loop back path has an intentional phase shift that can be toggled between an off state and an on state by the control system. The control system is configured to calculate the intentional phase shift by examining the difference of a first and second phase angle. The first phase angle is obtained from the transmission of a first pair of signals with the intentional phase shift in the off state. The second phase angle is obtained from the transmission of a second pair of signals with the intentional phase shift in the on state.

Abstract: A system for reducing a mismatch between an in-phase (I) signal and a quadrature phase (Q) signal is disclosed. The system includes a phase compensation block comprising an infinite impulse response (IIR) filter configured to reduce a first portion of a mismatch between an I signal and a Q signal, wherein the first portion includes frequency selective phase mismatch. The system further includes a gain compensation block comprising a finite impulse response (FIR) filter configured to reduce a second portion of the mismatch, wherein the second portion includes frequency selective gain mismatch. The phase compensation block and the gain compensation block are calibrated at least in part based on a loopback signal, wherein the loopback signal is routed from a transmitting portion of a radio frequency (RF) circuitry back to a receiving portion of the RF circuitry.

Abstract: A wireless apparatus includes: an A/D converter which samples an in-phase signal component and a quadrature signal component from a quadrature-modulated signal of analog form alternately; a digital quadrature demodulation unit which applies digital quadrature demodulation to an output signal of the A/D converter and outputs an in-phase signal and a quadrature signal; and an error detection unit which, based on the in-phase and quadrature signals output from the digital quadrature demodulation unit, detects a time difference error between the sample timing of the in-phase signal component and the sample timing of the quadrature signal component.

Abstract: A multi-user MIMO downlink beamforming system with limited feedback (200) is provided to enable precoding for multi-stream transmission, where a channel codeword (ui) and one or more channel quality indicator values (CQIA, CQIB) are computed at the user equipment (201.i) on the basis of maximizing a predetermined SINR performance metric (?i) which estimates the receive signal-to-noise-ratio (SINR) at the user equipment (201.i). The computed codeword (ui) and CQI values (or differential values related thereto) are quantized and fed back to help the base station (210) which applies a correction to the appropriate CQI value in the course of designing the transmit beamforming vectors w and determining the appropriate modulation and coding level to be used for downlink data transmission.

Abstract: A communication system adaptively cancels noise and/or interference from signals communicated through a communication channel, such as signals communicated by a telecommunication network. The system, based on a common mode signal of a received signal, generates an estimate of noise or interference within a differential mode signal of the received signal. The system then subtracts the estimate from the differential mode signal in an effort to remove noise from the differential mode signal thereby providing a differential mode signal that is substantially free of the estimated noise or interference.

Abstract: An access node of a communication system comprises a plurality of transmitters adapted for communication with at least one receiver. The access node is operative to transmit pilot signals from respective associated ones of the transmitters, to estimate channel coefficients between the transmitters and the receiver, and to utilize the estimated channel coefficients to control at least one data signal sent by at least one of the transmitters. The pilot signals are partitioned into a plurality of sets of pilot signals such that pilot signals from the same set have respective subpilots that are orthogonal to one another and pilot signals from different sets have respective subpilots that are not orthogonal to one another but are instead quasi-orthogonal to one another. The pilot signals are associated with the respective transmitters based on the partitioning of the pilot signals into sets.

Abstract: A PDMA terminal establishes communication by forming a plurality of spatial paths to another single radio apparatus. A plurality of antennas constituting an array antenna are divided into a plurality of subarrays corresponding to the plurality of spatial paths respectively. An adaptive array processing unit can perform an adaptive array processing for each of the plurality of subarrays. A memory stores in advance information on the number of antennas associated with the number of spatial paths that can be formed by the array antenna. A control unit controls a processing to transmit possible multiplicity information to another radio apparatus at a prescribed timing.

Abstract: The semiconductor integrated communication circuit includes: a low-noise amplifier; a receive mixer; a receive VCO; a demodulation-processing circuit; a modulation-processing circuit; a transmit mixer; a transmit VCO; a second-order-distortion-characteristic-calibration circuit; a quadrature-receive-signal-calibration circuit; and a test-signal generator. The test-signal generator generates first and second test signals using the transmit VCO. In the second-order-distortion-characteristic-calibration mode, the second-order-distortion-characteristic-calibration circuit variably changes an operation parameter of the receive mixer thereby to calibrate the second-order distortion characteristic to achieve its best condition while the first test signal is supplied to the receive mixer.

Abstract: A method, system, and device for power optimization based on Digital Subscriber Line (DSL) are provided. The method includes the following steps. Service information of a subscriber is collected, and physical layer target parameters are obtained according to Quality of Experience (QoE) parameters corresponding to the service information. Line running information of the subscriber is received. The physical layer target parameters and the line running information are used as input parameters of a power optimization algorithm, and an optimized power spectrum is obtained through the power optimization algorithm. Therefore, a DSL network is optimized according to the QoE, and subscriber's experience is improved. Moreover, a least power method is adopted to optimize a transmit power spectrum, and the total power consumption and crosstalk between different DSL signals are reduced while meeting the QoE, so that the signal transmission of the system is stable, and the service transmission quality is improved.

Abstract: System for measuring satellite downlink amplifier linearity includes a pulsed signal generator for selectively generating low duty cycle pulses. A linear transmitter uplink amplifier is provided for amplifying the low duty cycle pulses and generating an uplink signal. An antenna transmits the amplified uplink signal to an orbiting satellite. A downlink amplifier in the satellite generates a downlink signal for re-transmission to an Earth-based antenna. A pulse receiver is provided for receiving the downlink signal and providing information regarding the transfer function of the downlink amplifier. Preferably, a delayed trigger circuit is coupled to the pulse signal generator for activating the pulsed signal generator after a time delay substantially corresponding to the propagation times of the uplink and downlink signals.

Abstract: The present application discloses systems and methods for reducing output-to-input feedback signal interference caused by a forwarding node that is configured to forward information received from a transmitter. In some embodiments, this output-to-input feedback signal interference is compensated for by the transmitter. For example, the transmitter is configured such that the signal that is transmitted by transmitter to the forwarding node includes both (1) a primary signal or ‘desired’ signal (e.g., the signal that is intended for a receiving device) and (2) a filtered version of the primary signal. The filter that produces the filtered version of the primary signal is configured (e.g., the filter's filter weights are adapted) such that the filtered version of the primary signal cancels or reduces the undesired output-to-input feedback signal.

Abstract: A method for communication includes transmitting data from a transmitter to a receiver using Adaptive Coding and Modulation (ACM). The data rate is set by selecting, based on feedback, an ACM profile defining a Forward Error Correction code and a modulation scheme. Upon detecting that the feedback is unusable, an operation of the transmitter is changed independently of the feedback. In another method, data is exchanged over two opposite directions of a bidirectional link that uses ACM by communicating using two ACM profiles. A joint constraint is defined on the two directions. The two ACM profiles are set based on first and second measured reception quality metrics of the two link directions, to meet the joint constraint. In yet another method, a subset of the ACM profiles is temporarily disabled, and the data is transmitted using only the ACM profiles that are not disabled.

Abstract: Testing a plurality of communication devices. A plurality of signals may be received from the plurality of communication devices. The plurality of signals may include a signal from each of the plurality of communication devices, where a first subset of the plurality of signals has a different frequency than a second subset of the plurality of signals. The received signals may be combined into a combined signal. The combined signal may be downconverted to a combined signal, e.g., by mixing the combined signal with an output from at least one local oscillator. The downconverting may generate a plurality of lower frequency signals, each corresponding to one of the plurality of received signals. Testing may be performed on each of the plurality of lower frequency signals.

Abstract: Embodiments of the present invention provide an apparatus comprising a transceiver having a receiver and a transmitter connected through a segment of a calibration loop back path. The apparatus also comprises a control system configured to communicate with the transceiver. The calibration loop back path has an intentional phase shift that can be toggled between an off state and an on state by the control system. The control system is configured to calculate the intentional phase shift by examining the difference of a first and second phase angle. The first phase angle is obtained from the transmission of a first pair of signals with the intentional phase shift in the off state. The second phase angle is obtained from the transmission of a second pair of signals with the intentional phase shift in the on state.

Abstract: A system and method is provided for phase interpolator based transmission clock control. The system includes a transmitter having a phase interpolator coupled to a master timing generator and a transmission module. The phase interpolator is also coupled to a receiver interpolator control module and/or an external interpolator control module. When the system is operating in repeat mode, the transmitter phase interpolator receives a control signal from a receiver interpolator control module. The transmitter phase interpolator uses the signal to synchronize the transmission clock to the sampling clock. When the system is operating in test mode, a user defines a transmission data profile in an external interpolator control module. The external interpolator control module generates a control signal based on the profile. The transmitter phase interpolator uses the signal to generate a transmission clock that is used by the transmission module to generate a data stream having the desired profile.

Abstract: A system and apparatus are disclosed for a method and apparatus for equalizing signals. An apparatus that incorporates teachings of the present disclosure may include, for example, an equalizer (100) having a channel estimation calculator (102) for calculating a time domain channel estimation from a baseband signal, an FFT processor (104) for translating the time domain channel estimation to a frequency domain channel estimation, a tap weight calculator (106) for calculating a frequency domain tap weight according to the frequency domain channel estimation, an inverse FFT processor (108) for translating the frequency domain tap weight calculation to a time domain tap weight calculation, and a filter (110) for equalizing the baseband signal according to the time domain tap weight calculation.

Abstract: A communications system includes a target receiver having a passband and configured to receive an intended signal within the passband. The communications system also includes a jammer configured to jam the target receiver from receiving the intended signal. The jammer has at least one antenna, a jammer receiver coupled to the at least one antenna, a jammer transmitter coupled to the at least one antenna, and a controller configured to cooperate with the jammer receiver. The controller is configured to detect the intended signal and to generate an interfering signal comprising a continuous phase modulation (CPM) waveform having a constant envelope so that the interfering signal at least partially overlaps the passband of the target receiver.

Abstract: Disclosed is a method for generating feedback signal patterns of common feedback channels using cyclic shift in a multiple access system, and a transceiver therefore. A method for generating feedback signal patterns includes generating first transmission symbols by adding a cyclic prefix to transmission symbols of feedback signals, and generating second and subsequent transmission symbols by cyclically shifting the first transmission symbols and then adding the cyclic prefix.

Abstract: A method for reducing spurs within a transmit signal is disclosed. A cancelling tone is determined. The cancelling tone is added to a baseband transmit signal in the digital domain to obtain a baseband transmit signal with cancelling tone. A spur in the transmit signal is reduced using the cancelling tone. The transmit signal with the reduced spur is transmitted using an antenna.

Abstract: A wireless communication apparatus includes a loopback transfer function acquisition section that, when a first path including all paths from each branch of the first set to each branch of the second set via the antenna is formed, acquires a loopback transfer function of each path included in the first path based on a reception status of a reference signal transmitted from each branch of the first set and received by each branch of the second set, and when a second path opposite to the first path is formed, acquires a loopback transfer function of each path included in the second path based on a reception status of a reference signal transmitted from each branch of the second set and received by each branch of the first set, and a calibration factor calculation section to calculate a calibration factor of each branch based on the acquired loopback transfer functions.

Abstract: A device and method for precoding vectors in a communication system is provided. A transmitter may precode a data vector using information regarding a communication channel prior to transmitting the data vector. The transmitter may precode the data vector in a manner that reduces an energy value of a resulting transmit data vector so as to minimize interference in a received signal at a receiver. The transmitter may perturb entries of the data vector one-by-one in an iterative fashion until a minimum in an energy value of the transmit data vector is obtained.

Abstract: A wireless commutation device includes: an antenna unit including antennas transmitting and receiving wireless signals; an analog processing unit including transmitting analog circuits and receiving analog circuits processing analog transmitting and received signals; a digital processing unit processing digital transmitting and received signals; an inter-antenna propagation loss determination unit determining propagation losses between the antennas; a loopback transfer function gain acquisition unit acquiring, through loopback of a calibration signal between the antennas, gains of loopback transfer functions between antenna branches; a loopback transfer function gain correction unit correcting the gains by using the propagation losses; a correction coefficient determination unit determining the respective gain ratios among the receiving analog circuits and the transmitting analog circuits by using the corrected gains, and determining correction coefficients by using the gain ratios; and a gain calibration pro

Abstract: Techniques are provided to improve wireless beamformed communication between first and second wireless communication devices. At a plurality of antennas of the first wireless communication device (e.g., a base station) uplink transmissions sent from the second wireless communication device (e.g., a client or mobile device or station) are received. The first wireless communication device generates a downlink beamforming weight vector from received uplink transmissions, and computes a covariance matrix for received uplink transmissions. The first wireless communication device stores history information based on the covariance matrices for received uplink transmissions. The first wireless communication device computes first and second beamforming-space time code weight vectors based on the covariance matrix for an uplink transmission received in a current frame and the history information.

Abstract: A method of adaptively selecting a modulation and coding scheme (MCS) of a communication link includes obtaining a first parameter corresponding to a Quality of Service (QoS) requirement of the communication link, obtaining a second parameter indicative of a physical condition of the communication link, selecting an MCS based on at least the first parameter and the second parameter.

Abstract: A transceiver capable of IQ mismatch compensation on the fly and a method thereof. The transceiver comprises a transmitter circuit and a loop-back circuit. The transmitter circuit is configured to up-convert a modulation signal on the fly to generate a first RF signal. The loop-back circuit is configured to down-convert the first RF signal and then digitize the down-converted first RF signal to determine a first IQ mismatch parameter based on a first statistical measure of the digitized down-converted RF signal. The transmitter circuit is further configured to compensate for first IQ mismatch in the transmitter circuit according to the first IQ mismatch parameter to generate an IQ compensated modulation signal.

Abstract: A transceiver includes a transmitter circuit, a receiver circuit, and the loopback switch. The transmitter circuit performs a digital-to-analog conversion (DAC) operation on a calibration code without a transmission digital signal in a calibration mode to generate a calibration signal. The transmitter circuit up-converts the calibration signal and generates a transmission signal. The receiver circuit down-converts the transmission signal in the calibration mode and generates a receiving digital signal. The loopback switch electrically connects an output terminal of the transmitter circuit and an input terminal of the receiver circuit in the calibration mode. Thus, the transceiver may stably reduce a carrier leakage irrespective of processes, voltages, and temperatures.

Abstract: The disclosure can provide methods and systems for autocalibrating a transceiver. The method can include upconverting a bandpass input signal by mixing the bandpass input signal with a first local oscillator signal to form an initial transmitter signal. The initial transmitter signal can be looped back to a receiver and downconverted with a second local oscillator signal having a frequency that is different from the first local oscillator to form an intermediate frequency signal. At least one of a gain and a phase of the transmitter can be adjusted based on a transmitter image sideband of the intermediate frequency signal to generate a calibrated transmitter signal having minimized transmitter image sideband.

Abstract: Described embodiments provide a method and system for signal compensation in a SERDES communication system that includes monitoring the quality of a data signal after passing through a transmission channel. The quality of the data signal is monitored with at least one of a BER calculation algorithm and a received eye quality monitoring algorithm. Variations in channel length of the transmission channel are compensated for by i) adjusting a length of transmission line delay of the data signal from the transmission channel, ii) comparing the data signal quality with a threshold for the adjusted data signal; and iii) repeating i) and ii) until the data signal quality meets the threshold.

Abstract: A first periodic signal generation circuit generates first periodic output signals. A second periodic signal generation circuit generates second periodic output signals. A first multiplexer circuit receives the first and the second periodic output signals. An interface circuit coupled to external pins generates a third periodic output signal based on a periodic signal selected by the first multiplexer circuit. A second multiplexer circuit receives the third periodic output signal at an input. A first periodic feedback signal provided to the first periodic signal generation circuit is based on a signal selected by the second multiplexer circuit. A third multiplexer circuit receives the third periodic output signal at an input. A second periodic feedback signal provided to the second periodic signal generation circuit is based on a signal selected by the third multiplexer circuit.

Abstract: Embodiments of a method and apparatus for reducing non-linear transmit signal components of a receive signal of a transceiver signal are disclosed. The method includes the transceiver simultaneously transmitting a transmit signal, and receiving the receive signal. A non-linear replica signal of non-linear transmission signal components that are created in the transceiver by a transmit signal DAC, and imposed onto the receive signal, is generated. The non-linear replica signal is subtracted from the received signal reducing the non-linear transmission signal components imposed onto the receive signal.

Abstract: Methods and apparatus are provided for pseudo asynchronous testing of receive paths in serializer/deserializer (SerDes) devices. A SerDes device is tested by applying a source of serial data to a receive path of the SerDes device during a test mode. The receive path substantially aligns to incoming data using a bit clock. A phase is adjusted during the test mode of the bit clock relative to the source of serial data to evaluate the SerDes device. The source of serial data may be, for example, a reference clock used by a phase locked loop to generate the bit clock. The phase of the bit clock can be directly controlled during the test mode, for example, by a test phase control signal, such as a plurality of interpolation codes that are applied to an interpolator that alters a phase of the bit clock.

Abstract: Aspects of a method and system for compensating for estimated distortion in a transmitter by utilizing a digital predistortion scheme with a quadrature feedback mixer configuration are presented. Aspects of the system may include an RF transmitter that enables generation of an RF output signal in response to one or more generated input signals. One or more feedback signals may be generated by performing frequency downconversion on the RF output signal within a corresponding one or more feedback mixer circuits. The generated one or more feedback signals may be inserted at a corresponding one or more insertion points in an RF receiver. Each insertion point may be between a receiver mixer circuit and corresponding circuits that generate a baseband signal based on the corresponding one of the feedback signals.

Abstract: A data-transmission-side communication apparatus includes a mapping unit that executes a mapping for a data sub-carrier based on a multipath delay time in a transmission path and a guard-band adding unit that changes an amount of a guard band to be added to a signal on the data sub-carrier depending on information on the guard band obtained based on the multipath delay time. A data-reception-side communication apparatus includes an equalizing unit that suppresses a multipath exceeding a guard interval based on the information on the guard band and a demapping unit that executes a demapping for an equalized signal based on the multipath delay time.

Abstract: Embodiments of a method and apparatus of reducing transmit signal components of a receive signal of a transceiver are disclosed. One embodiment of an apparatus includes a transceiver that simultaneously transmits a transmit signal and receives a receive signal. The transceiver includes a transmit DAC that generates the transmit signal based on a transmit digital signal stream. The transmit DAC includes a plurality of transmit DAC circuit elements, and a plurality of transmit DAC switches that control which of the plurality of transmit DAC circuit elements contribute to generating the transmit signal. The transceiver additionally includes an echo cancellation DAC that generates an echo cancellation signal based on the transmit digital signal stream.

Abstract: A method includes broadcasting, at a transmitter, messages comprising antenna configuration, antenna spacing and a number of antenna of the transmitter and reference signals; generating, at a receiver, a codebook comprising a plurality of antenna beams based on the broadcasted messages; receiving, at the receiver, the broadcasted reference signals; selecting, at the receiver, an antenna beam among the plurality of antenna beams within the codebook in dependence upon a predetermined performance criteria of a data communication system and in dependence upon the broadcasted reference signals; feedbacking to the transmitter, at the receiver, information comprising the antenna beam selected by the receiver; optimizing, at the transmitter, a beamforming process by utilizing the feedback information from the receiver; transmitting, at the transmitter, data signals by utilizing the optimized beamforming process; and receiving and processing, at the receiver, the data signals in dependence upon the selected antenna be

Abstract: An access node of a communication system comprises a plurality of transmitters adapted for communication with at least one receiver. The access node is operative to simultaneously estimate channel coefficients between multiple ones of the transmitters and the receiver, and to utilize the estimated channel coefficients to control at least one data signal sent by at least one of the multiple transmitters to the receiver. In the process of simultaneously estimating the channel coefficients, the access node transmits a plurality of distinct probing signals generated based on respective ones of a plurality of different frequency expansions. For example, each of the distinct probing signals may be generated based on a distinct combination of a common probing sequence and a selected one of the plurality of different frequency expansions.

Abstract: An apparatus comprising an artificial noise (AN) controller coupled to a digital subscriber line (DSL) transmitter and configured to adjust an AN level for a signal transmitted by the DSL transmitter, wherein the AN level is adjusted based on an actual signal to noise ratio (SNR) of the signal from the receiver to achieve a desired SNR for the signal. Also disclosed is a method comprising maintaining a data rate in a line at about a desired level by adjusting an AN level in a transmitted signal based on a SNR of a received signal.