Tue, 10 May 2016 08:00:00 EDTA method and device that interrogates the availability of a called party before placing a communication from the calling party to the called party. A callback may be initiated so that both communications are completed simultaneously. The routing of communication may take place through any one of a number of different networks and at another time of the day, even if the caller does not otherwise have access to those networks.
Tue, 10 May 2016 08:00:00 EDTA method is provided for improving synchronization and information transmission in a communication system, including: generating a signal with a centrally symmetric part s(k) exploitable for synchronization; and sending the signal over a communication channel. The signal is based on a uniquely identifiable sequence c(l) from a set of sequences exploitable for information transmission. The centrally symmetric part s(k) is centrally symmetric in the shape of absolute value thereof. The centrally symmetric part s(k) is of arbitrary length N.
Tue, 13 Oct 2015 08:00:00 EDTVarious methods and systems for efficiently performing the blind decoding of downlink signals is described. Several forms of arranging possible CCE combinations are examined and investigated. Based on PDCCH size estimation/information, CCE concatenations that are most likely (of of limited sets) can be arrived at. Tree-based concatenations are also devised using largest CCE ordering to align smaller CCE sizes to similar boundaries. By such ordering, the search space for all possible CCE ordering and sizes can be reduced to an efficient tree. Set mapping between possible lnposelstartCCElnposelend/REs are also described using a first set to secondary and tertiary sets. Various other ordering and sorting schemes are also detailed that enable a blind decode of a PDCCH channel to be efficiently performed.
Tue, 11 Aug 2015 08:00:00 EDTA transport stream (TS) generating apparatus, a transmitting apparatus, a receiving apparatus, a digital broadcast system having the above, and a method thereof are provided. The digital broadcast system includes a transport stream (TS) generating apparatus which generates a multi transport stream (TS) by multiplexing a normal stream and a turbo stream having a variable coding rate, a transmitting apparatus which re-constructs the multi TS by processing the turbo stream, and transmits the re-constructed multi TS, and a receiving apparatus which receives the re-constructed multi TS, and decodes the normal stream and the turbo stream respectively, to recover normal data and turbo data. Accordingly, a multi TS, which includes normal stream and a turbo stream of various coding rates, can be transmitted and received efficiently.
Tue, 28 Jul 2015 08:00:00 EDTA method includes extracting a first vector used to code a specific block belonging to a coded field picture arranged chronologically adjacent to a field picture to be coded and to a block to be coded, generating a second vector by scaling the first vector based on a temporal distance between the field picture and a second picture specified by a reference index and referenced for the block and included in the field picture and a temporal distance between a first picture pointed by the first vector and the coded field picture arranged chronologically adjacent to the field picture, and correcting the second vector based on a parity of the field picture, a parity of the first picture, a parity of the second picture and a parity of the coded field picture and forming the corrected second vector.
Tue, 21 Jul 2015 08:00:00 EDTA decoder receives a bitstream containing quantized coefficients representative of blocks of video representative of a plurality of pixels and decodes the bitstream using context adaptive binary arithmetic coding that includes at least two decoding modes, the first mode decoding the bitstream based upon a probability estimate which is based upon at least one of spatially and temporally adjacent syntax element values to a current syntax element being decoded, the second mode decoding the bitstream not based upon a probability estimate based upon other syntax elements to the current syntax element being decoded. The coding decodes the current syntax element using the first mode if the current syntax element is intra-coded and selecting between sets probable modes with different probabilities. The coding decodes the current syntax element using the second mode if the current syntax element is intra-coded and if selecting among one of the second set of probable modes.
Tue, 07 Jul 2015 08:00:00 EDTA radio communication device capable of randomizing both inter-cell interference and intra-cell interference. In this device, a spreading section (214) primarily spreads a response signal in a ZAC sequence set by a control unit (209). A spreading section (217) secondarily spreads the primarily spread response signal in a block-wise spreading code sequence set by the control unit (209). The control unit (209) controls the cyclic shift amount of the ZAC sequence used for the primary spreading in the spreading section (214) and the block-wise spreading code sequence used for the secondary spreading in the spreading section (217) according to a set hopping pattern. The hopping pattern set by the control unit (209) is made up of two hierarchies. An LB-based hopping pattern different for each cell is defined in the first hierarchy in order to randomize the inter-cell interference. A hopping pattern different for each mobile station is defined in the second hierarchy in order to randomize the intra-cell interference.
Tue, 09 Jun 2015 08:00:00 EDTIn this VSWR measurement circuit, a power measurement unit measures the power level of a reflected signal which is included in a feedback signal which has been extracted at a second CPL which has been deployed at a position connecting to an antenna end via a cable. To this end, the VSWR measurement circuit is provided with a main signal component removal circuit, wherein the main signal which has been extracted from the prestage of a digital pre-distortion circuit, and a signal in which the feedback signal that had been extracted at the second CPL has been converted to a digital signal at an A/D CONV, are provided as inputs, the main signal component included in the feedback signal is removed, and only the reflected signal is extracted so as to be output to the power measurement unit.
Tue, 09 Jun 2015 08:00:00 EDTTransmission quality is improved in an environment in which direct waves dominate in a transmission method for transmitting a plurality of modulated signals from a plurality of antennas at the same time. All data symbols used in data transmission of a modulated signal are precoded by hopping between precoding matrices so that the precoding matrix used to precode each data symbol and the precoding matrices used to precode data symbols that are adjacent to the data symbol in the frequency domain and the time domain all differ. A modulated signal with such data symbols arranged therein is transmitted.
Tue, 02 Jun 2015 08:00:00 EDTMultiple-Input and Multiple-Output (MIMO)-Orthogonal Frequency Division Multiplexing (OFDM) communication is provided which allows high accuracy estimation of frequency offset, high accuracy estimation of a transmission path fluctuation and high accuracy synchronization/signal detection. Pilot symbol mapping is provided for forming pilot carriers by assigning orthogonal sequences to corresponding subcarriers among OFDM signals which are transmitted at the same time from respective antennas in the time domain. Even when pilot symbols are multiplexed among a plurality of channels (antennas), this allows frequency offset/phase noise to be estimated with high accuracy.
Tue, 02 Jun 2015 08:00:00 EDTProvided is a precoding method for generating, from a plurality of baseband signals, a plurality of precoded signals to be transmitted over the same frequency bandwidth at the same time, including the steps of selecting a matrix F[i] from among N matrices, which define precoding performed on the plurality of baseband signals, while switching between the N matrices, i being an integer from 0 to N−1, and N being an integer at least two, generating a first precoded signal z1 and a second precoded signal z2, generating a first encoded block and a second encoded block using a predetermined error correction block encoding method, generating a baseband signal with M symbols from the first encoded block and a baseband signal with M symbols the second encoded block, and precoding a combination of the generated baseband signals to generate a precoded signal having M slots.
Tue, 02 Jun 2015 08:00:00 EDTTechniques for extracting the characteristic response of a non-linear channel are presented. In various implementations of the invention, a channel's characteristic response may be determined by identifying a first input sequence, determining the ones compliment of the first input sequence and then determining the response of the channel to these two input sequences. Subsequently, two input matrices and two response matrices may be generated based upon the two input sequences and their corresponding responses. Given these four matrices, a symmetrical response component may be determined by iteratively solving a system of equations formed from the columns of each matrix. Subsequently, given the symmetric component and these four matrices, an asymmetrical response component may be determined by again iteratively solving the system of equations for the columns of each matrix.
Tue, 26 May 2015 08:00:00 EDTIn order to transmit a large amount of data in series at a time with a MIMO communication scheme while avoiding deterioration of decoding characteristics due to change over time by a channel matrix, a wireless communication system uses an open-loop type and a closed-loop type of MIMO communication modes in combination and switches to the open-loop MIMO communication mode in response to the information that the amount of data to be transmitted at a time has exceeded a predetermined amount of bits or a predetermined transmission time during data transmission under the closed-loop MIMO communication mode. By discontinuing useless closed-loop MIMO communication and switching to the open-loop MIMO communication mode that is better than Zero-forcing, the decoding characteristics are prevented from simply becoming deteriorated.
Tue, 26 May 2015 08:00:00 EDTA coupling device for use in a hybrid fiber coaxial (HFC) network may be configured to disable an upstream path through it when there is only noise incident on the upstream path, and enable the upstream path through it when a desired transmission from a cable modem downstream of the coupling device is incident on the upstream path. The coupling device may be a trunk amplifier, a distribution amplifier, a splitter, or the like. The coupling device may comprise a single upstream interface coupled to a plurality of downstream interfaces. The enabling and/or disabling may be in response to a signal strength indicated by the SSI being below a threshold and/or in response to one or more control messages indicating whether any downstream cable modem is, or will be, transmitting.
Tue, 26 May 2015 08:00:00 EDTA system for communicating a dataset may include at least a first and a second communication line. The system may also include a first transceiver configured to communicate a first data signal indicative of the dataset over the first communication line and a second transceiver configured to communicate a second data signal indicative of the dataset over the second communication line. The system may also include a processor. The processor may be configured to receive the first data signal and the second data signal and compare the first data signal and the second data signal to determine whether the first data signal or the second data signal comprises a more accurate signal. The processor may also be configured to determine the dataset based upon the more accurate signal.
Tue, 26 May 2015 08:00:00 EDTA communication device and a power control method thereof are provided. The power control method, performed by a communication device, includes: determining a power range of a transmit power of an uplink signal; determining a gain switch range based on the power range; when the transmit power of the uplink signal is within the gain switch range, determining a first gain mode for amplifying the uplink signal; and when the transmit power of the uplink signal is out of the gain switch range, determining a second gain mode for amplifying the uplink signal.
Tue, 26 May 2015 08:00:00 EDTA mobile wireless device maintains a radio sector database. When receiving no response or a negative response from a radio sector to a transmitted signaling message, the mobile wireless device adds or updates the radio sector database. When receiving a positive response from the radio sector, the mobile wireless device deletes the radio sector from the radio sector database. Before transmitting signaling messages to a radio sector, the mobile device determines a time delay value if the radio sector is in the radio sector database. The mobile wireless device discards the signaling message when an elapsed time since a most recently transmitted signaling message to the radio sector does not exceed the determined time delay value. In an embodiment, each radio sector in the radio sector database includes a failure count value, and the determined time delay value depends on the failure count value.
Tue, 26 May 2015 08:00:00 EDTA method of calibrating an envelope tracking system for a supply voltage for a power amplifier module within a radio frequency (RF) transmitter module. The method includes deriving a mapping function between an instantaneous envelope of a waveform signal to be amplified by the power amplifier module and the power amplifier module supply voltage to achieve a constant power amplifier module gain based on a gain compression factor, setting an envelope tracking path of the transmitter module into an envelope tracking mode in which mapping between the instantaneous envelope of the waveform signal and the power amplifier module supply voltage is performed using the derived mapping function, applying a training signal comprising an envelope that varies with time to the RF transmitter module, measuring a battery current, modifying the gain compression factor based on the measured battery current, and re-deriving the mapping function based on the modified gain compression factor.
Tue, 26 May 2015 08:00:00 EDTIn a wireless network, plural downlink signals from plural base stations are transmitted to a terminal. The plural downlink signals all carry the same information to the terminal. The terminal provides feedback on the downlink channels. The feedback provides information on the taps of the channels. The amount of information fed back is constrained. Based on the feedback, transmission parameters of the downlink signals are adjusted. The process of transmitting, providing feedback, and adjusting the parameters continue so that the energy of the downlink signal is enhanced at the terminal location and suppressed elsewhere. Beam forming can be used to further suppress the energy signature at locations other than the terminal location.
Tue, 26 May 2015 08:00:00 EDTThe present invention relates to a wireless transmission system for signals intended more specifically for a domestic environment. It includes a central terminal comprising at least m transmission channels and n directive transmission antennas intended to transmit first signals at least one client terminal having at least one reception channel connected to a reception antenna in order to receive the first signals said central terminal and said client terminal communicating in a transmission channel having a predetermined frequency band, and an estimation device able to generate an item of information representative of the reception quality of first signals in at least one point of a predetermined geographic zone associated with the client terminal and a return channel in order to transmit said at least one item of information to the control means of the central terminal.
Tue, 26 May 2015 08:00:00 EDTAspects of the subject disclosure may include, for example, a system including a frequency mixer that combines a signal and a carrier wave to form a combined signal, and a transmitter that generates a transmission based on the combined signal. The system can also include a coupling device that emits the transmission as an electromagnetic wave guided by an outer surface of a transmission medium. The electromagnetic wave can propagate longitudinally along the surface of the transmission medium and at least partially around the surface of the transmission medium. Other embodiments are disclosed.
Tue, 26 May 2015 08:00:00 EDTDescribed herein are systems and methods for accurately estimating and removing a carrier frequency offset. One exemplary embodiment relates to a system comprising a frequency offset detection circuit detecting a carrier frequency offset in an optical signal, and a frequency testing circuit calculating an estimated frequency offset value of the carrier frequency offset, wherein the frequency testing circuit removes a carrier phase based on the estimated frequency offset value and recovers the optical signal. Another exemplary embodiment relates to a method comprising detecting a carrier frequency offset in an optical signal, calculating an estimated frequency offset value of the carrier frequency offset, removing a carrier phase based on the estimated frequency offset value, and recovering the optical signal.
Tue, 26 May 2015 08:00:00 EDTA direction of regularity, which minimizes a directional energy computed from pixel values of consecutive first and second frames of an input video sequence, is respectively associated with each pixel of the first frame and with each pixel of the second frame. Another direction of regularity (vz), which minimizes a directional energy computed from pixel values of the first and second frames, is also associated with an output pixel (z) of a frame of an output video sequence, located in time between the first and second frames. For processing such output pixel, the respective minimized directional energies for the output pixel, at least one pixel (z′) of the first frame and at least one pixel (z″) of the second frame are compared to control an interpolation performed to determine a value of the output pixel. The interpolation uses pixel values from at least one of the first and second frames of the input video sequence depending on the comparison of the minimized directional energies.
Tue, 26 May 2015 08:00:00 EDTA method and apparatus prioritizing video information during coding and decoding. Video information is received and an element of the video information, such as a visual object, video object layer, video object plane or keyregion, is identified. A priority is assigned to the identified element and the video information is encoded into a bitstream, such as a visual bitstream encoded using the MPEG-4 standard, including an indication of the priority of the element. The priority information can then be used when decoding the bitstream to reconstruct the video information.
Tue, 26 May 2015 08:00:00 EDTThe present invention discloses a dual-channel analog door entry system and a method thereof. The dual-channel analog door entry system comprises two cables connected between the building gateway and the floor distributors, configured to transmit audio and/or video signals between the outdoor stations and indoor phones; the building gateway, configured to receive a call request from at least one of the outdoor stations, identify and assign an available cable as an intercom channel, send the call request to each of the floor distributors via the intercom channel, and switch the audio and/or video signals from the outdoor station to the available cable; at least one of floor distributors, configured to receive and forward the call request to a desired indoor phone, receive a call response from the desired indoor phone if the desired indoor phone is available, and switch the audio and/or video signals from the available cable to the desired indoor phone. The solutions of the present invention achieves great improvement on line busy probability for large buildings and communities; and the solution is smart and simple to implement with low additional cost for reconstruction.
Tue, 26 May 2015 08:00:00 EDTSystems and methods for discrete signal synchronization based on a known bit pattern are described. In one aspect of the present subject matter, a discrete signal synchronization system is configured to synchronize a preprocessed discrete signal with a modified discrete signal. The system comprises a processor and a synchronization module coupled to the processor. The synchronization module comprises an extraction module and comparison module. The extraction module determines a bit pattern from the modified discrete signal using Discrete Wavelet Transformation (DWT) and Singular Value Decomposition (SVD). The comparison module compares the determined bit pattern with a known bit pattern of the preprocessed discrete signal and records a time point at which the determined bit pattern matches with the known bit pattern of the preprocessed discrete signal as a synchronization point.
Tue, 26 May 2015 08:00:00 EDTA data transmission apparatus disposed within two network layers operative at different data rates is provided. The data transmission apparatus is coupled to a clock generator which provides a reference clock for a lower network layer and is coupled to a frequency synthesizer with an integer division factor that generates a divided clock for an upper network layer according to the reference clock and the integer division factor. The data transmission apparatus includes a first processing circuit and a second processing circuit. The first processing circuit corresponding to the upper network layer receives and transmits data by using the divided clock as its operation frequency. The second processing circuit corresponding to the lower network layer receives and transmits data from the first processing circuit by using the reference clock as an operation frequency for encoding data. The divided clock is generated from the frequency synthesizer with the integer division factor.
Tue, 26 May 2015 08:00:00 EDTA method and system provides for execution of calibration cycles from time to time during normal operation of the communication channel. A calibration cycle includes de-coupling the normal data source from the transmitter and supplying a calibration pattern in its place. The calibration pattern is received from the communication link using the receiver on the second component. A calibrated value of a parameter of the communication channel is determined in response to the received calibration pattern. The steps involved in calibration cycles can be reordered to account for utilization patterns of the communication channel. For bidirectional links, calibration cycles are executed which include the step of storing received calibration patterns on the second component, and retransmitting such calibration patterns back to the first component for use in adjusting parameters of the channel at first component.
Tue, 26 May 2015 08:00:00 EDTIn a data recovery circuit, a sampling circuit is configured to sample data using a plurality of sampling clock signals having different phases relative to one another and to output a plurality of sampled data. A recovery data generation circuit is configured to perform a logic operation on the plurality of sampled data and to generate a plurality of intermediate recovery data according to a result of the logic operation. A recovery circuit is configured to check the plurality of intermediate recovery data for existence of an error and to output intermediate recovery data that is error-free, among the plurality of intermediate recovery data, as recovery data.
Tue, 26 May 2015 08:00:00 EDTA wideband multi-channel receiver comprises an antenna configured to receive a radio frequency band. A band-pass filter is in signal communication with the antenna, and a low-noise amplifier is in signal communication with the band-pass filter. A mixer is in signal communication with the low-noise amplifier and is configured to translate a radio frequency band to an intermediate frequency (IF) band. A tunable local oscillator is in signal communication with the mixer. At least one fixed-frequency notch filter is in signal communication with the mixer, with the notch filter configured to reject at least one interference signal in the IF band while passing remaining signals in the IF band. An analog-to-digital converter is in signal communication with the notch filter and is configured to convert the remaining signals in the IF band to digital signals.
Tue, 26 May 2015 08:00:00 EDTA receiving circuit, use, and method for receiving an encoded and modulated radio signal is provided. The circuit comprise a demodulator and a digital filter connected downstream of the demodulator for moving averaging. The filter has at least two FIFO registers and subtractors. Whereby for subtracting an output value of the FIFO register from an input value of the FIFO register a subtractor is connected to each FIFO register. Wherein the filter has a weighting unit, which is connected downstream of each FIFO register, and wherein the filter has an integrator, which is connected downstream of the subtractors for integration.
Tue, 26 May 2015 08:00:00 EDTA very-low intermediate frequency (VLIF) receiver and a method of controlling a VLIF receiver. The method comprises receiving a first signal, the first signal including one or both of an on-channel signal portion and an adjacent channel interferer (ACI) portion; determining that the first signal includes a portion having a strength that is above a threshold; in response to determining that the first signal includes a portion having a strength that is above the threshold, estimating one or more IQ imbalance parameters for at least a portion of the first signal; and compensating for an IQ imbalance in at least the portion of the first signal using the one or more IQ imbalance parameters.
Tue, 26 May 2015 08:00:00 EDTRadio frequency (RF) receivers having whitened digital clocks and related methods are disclosed. Disclosed embodiments generate whitened clocks having random variations that are used to operate digital processing blocks so that interference created by the whitened clocks is seen as white noise within the received RF signal spectrum. RF input signals are received by RF front-ends (RFFEs) that output analog signals associated with channels within the RF input signals. These analog signals are converted to digital information and processed by digital receive path circuitry that outputs digital data associated with the channel. The digital receive path circuitry includes a whitened clock generator that generates a whitened clock having random variations and which a digital processing block that operates based upon the whitened clock. Further, the RFFE and the digital receive path circuitry are located within a single integrated circuit.
Tue, 26 May 2015 08:00:00 EDTIn general, the present invention provides methods and apparatuses for exploiting the extra degree of freedom provided by the sensing of the CM signal along with the DM signal at the receiver end of a wireline communication system. According to certain aspects, this extra degree of freedom can be used to cancel alien noises at the receiver in both upstream downstream directions. According to further aspects, a CM channel can be potentially used to exploit the diversity created in the CM channel along with the regular DM channel. This acts as the motivation for employing a diversity receiver scheme at the receiver, especially in downstream communications received at a Customer Premises.
Tue, 26 May 2015 08:00:00 EDTA system that incorporates the subject disclosure may include, for example, a process that includes adjusting a filter in electrical communication between an input terminal and a demodulator. The filter is applied to an information bearing signal, e.g., to mitigate interference, received at the input terminal, resulting in a filtered signal. An error signal is received, indicative of errors detected within information obtained by demodulation of a modulated carrier of the filtered signal. A modified filter state is determined in response to the error signal and the filter is adjusted according to the modified filter state, e.g., to improve mitigation of the interference. Other embodiments are disclosed.
Tue, 26 May 2015 08:00:00 EDTVarious embodiments associated with an at least fourth-order cumulant of a signal are described. The at least fourth-order noise-insensitive cumulant of the signal can be taken and compared against an at least fourth-order noise-insensitive cumulant of known signals. A match can be found between the signal and a known signal and from this match, a demodulation scheme of the signal can be determined. The demodulation scheme can be used to demodulate the signal.
Tue, 26 May 2015 08:00:00 EDTIn one embodiment, interference suppression is improved by improving convergence criteria. For some embodiments, convergence is improved by employing non-constant alpha-beta-weighting. For other embodiments, convergence is improved by employing successive interference suppression methods that have guaranteed convergence properties.
Tue, 26 May 2015 08:00:00 EDTA digital broadcasting receiving system is provided. A receiving module receives an M number of symbols each carrying an N number of subcarriers of a control signal. A converting module performs FFT on respective kth subcarriers of an ith symbol and an (i+1)th symbol to generate an (i, k)th converted value and an (i+1, k)th converted value. A demodulating module performs differential demodulation on the (i, k)th and (i+1, k)th converted values to generate an (i, k)th demodulation value. A combining module soft-combines the (i, 1)th demodulation value through the (i, N)th demodulation value to generate an ith prediction value corresponding to the ith symbol. A determining module identifies a synchronization segment in the control signal according to the 1st prediction value to the (M−1)th prediction value.
Tue, 26 May 2015 08:00:00 EDTA communication apparatus with a multiple-input and multiple-output (MIMO) channel, includes a minimum mean square error (MMSE) detector configured to estimate quadrature amplitude modulation (QAM) symbols based on signals received through the MIMO channel. The apparatus further includes a QAM demodulator configured to demodulate the estimated QAM symbols, and estimate a first posterior probability of each of encoded bits of the estimated QAM symbols, and a first module configured to remove a first prior probability of each of the encoded bits from the first posterior probability to generate soft estimates of the encoded bits. The apparatus further includes a channel decoder configured to decode the encoded bits based on the soft estimates, and generate an improved posterior probability of each of the encoded bits, and a second module configured to generate a second prior probability of each of the encoded bits based on the improved posterior probability.
Tue, 26 May 2015 08:00:00 EDTA demodulator processes a continuous-time signal to generate at a plurality of encoded bits. An inner decoder processes a first subset of bits within the plurality of encoded bits to correct selected ones of the first subset of bits to form a corrected first subset of bits and to generate partially corrected data from the plurality of encoded bits based on the corrected first subset of bits. An outer decoder processes the partially decoded data, to correct selected ones of a second subset of the plurality of encoded bits to form a corrected second subset of bits. A bit combiner generates data estimates by combining the corrected first subset of bits and the corrected second subset of bits.
Tue, 26 May 2015 08:00:00 EDTThis disclosure provides systems, methods, and apparatus for receiving paging messages in fast fading scenarios. In one aspect, a method of demodulating a paging message during an assigned time slot by a wireless communications apparatus operating in an idle mode is provided. The method includes determining, in anticipation of the assigned time slot, an expected time position corresponding to a path of a pilot signal having a greater signal strength relative to other pilot signals. The method further includes assigning a first demodulation element to demodulate the pilot signal with reference to the expected time position and assigning a second demodulation element to demodulate the pilot signal with reference to a time offset from the expected time position. Other aspects, embodiments, and features are also claimed and described.
Tue, 26 May 2015 08:00:00 EDTSystems and methods for carrier phase recovery are provided. One method includes providing a reference signal, detecting an input signal and determining a Signal to Noise Ratio (SNR) of the input signal. The method also includes employing a Minimum Mean Square Error (MMSE) algorithm based on the SNR to determine a Carrier Phase Recovery Loop (CPRL) bandwidth.
Tue, 26 May 2015 08:00:00 EDTA carrier frequency offset compensation method for a communication system is provided. The method includes: mixing, filtering and interpolating an input signal according to a mixing parameter, a first filtering parameter and a first interpolation parameter, respectively, to generate a processed result; calculating a carrier frequency offset estimation value of the input signal according to the processed result; adjusting the mixing parameter according to the carrier frequency offset estimation value; and mixing, filtering and interpolating the input signal according to the adjusted mixing parameter, a second filtering parameter and a second interpolation parameter, respectively. The first interpolation parameter is associated with a cut-off frequency corresponding to the first filtering parameter.
Tue, 26 May 2015 08:00:00 EDTA phase offset compensator for compensating a phase offset is provided. The phase offset includes a first phase sub-offset and a second phase sub-offset. The phase offset compensator includes a feedback loop comprising a first loop filter, the feedback loop being configured to compensate the first phase sub-offset of the phase offset, and a feed forward loop comprising a second loop filter, the feed forward loop being configured to compensate the second phase sub-offset of the phase offset.
Tue, 26 May 2015 08:00:00 EDTApparatus and methods disclosed herein perform gain, clipping, and phase compensation in the presence of I/Q mismatch in quadrature RF receivers. Gain and phase mismatch are exacerbated by differences in clipping between I & Q signals in low resolution ADCs. Signals in the stronger channel arm are clipped differentially more than weaker signals in the other channel arm. Embodiments herein perform clipping operations during iterations of gain mismatch calculations in order to balance clipping between the I and Q channel arms. Gain compensation coefficients are iteratively converged, clipping levels are established, and data flowing through the network is gain and clipping compensated. A compensation phase angle and phase compensation coefficients are then determined from gain and clipping compensated sample data. The resulting phase compensation coefficients are applied to the gain and clipping corrected receiver data to yield a gain, clipping, and phase compensated data stream.
Tue, 26 May 2015 08:00:00 EDTIn an angle modulated radio transmitter, the total power is the same when modulated or unmodulated. Angle modulation produces multiple sideband pairs. The power in the sidebands is derived from the carrier. When a complex modulating waveform is used, the power (and therefore the amplitude) of the carrier varies. A system and method is provided for dramatically minimizing, to nearly zero, the bandwidth needed to transmit digital information using sideband suppression of angle modulated signals. The systems described use various techniques to suppress sideband pairs, leaving the carrier signal. The amplitude variations of the carrier are used to convey information. In some examples, techniques are used to filter and/or phase out one or more sideband pairs, leaving the carrier signal.
Tue, 26 May 2015 08:00:00 EDTThe disclosure provides a method and device for retransmitting data under antenna gain imbalance, and the method includes: determining that gains of multiple antennas at a transmission terminal are imbalanced; using a better spatial sub-channel in the multiple antennas to retransmit data when streams transmitted by the multiple antennas adopt a same Modulation and Coding Scheme; and using a better spatial sub-channel in the multiple antennas to retransmit data and/or using a single-stream approach to retransmit data when the streams transmitted by the multiple antennas adopt different Modulation and Coding Schemes. The disclosure selects a corresponding retransmission approach according to the condition of a spatial sub-channel on which streams have an error, thus improving and ensuring success rate for retransmitting a stream.
Tue, 26 May 2015 08:00:00 EDTA method of transmitting a training signal in a Wireless Local Area Network (WLAN) system includes generating one or more first training signals for a first destination station and one or more second training signals for a second destination station by applying a mapping matrix P to a training signal generation sequence, mapping the first training signals and the second training signals to a plurality of antennas according to an antenna mapping matrix, and performing Inverse Fast Fourier Transform (IFFT) on each of the first training signals and the second training signals mapped to the plurality of antennas and transmitting the training signals through the plurality of antennas.
Tue, 26 May 2015 08:00:00 EDTAn apparatus and a method of compensating for an I/Q imbalance in a direct up-conversion system prevents the performance of the system from being deteriorated by efficiently compensating for an I/Q timing skew, an I/Q phase imbalance, and an I/Q gain imbalance by using a characteristic of an OFDM scheme in an Orthogonal Frequency Domain Multiple (Access) (OFDM(A)) system using a direct up-conversion scheme. According to the apparatus and the method of compensating for an I/Q imbalance in the direct up-conversion system of the present invention, an OFDM(A) system using a direct up-conversion scheme may efficiently compensate for I/Q timing skew, I/Q phase imbalance, and I/Q gain imbalance by using a characteristic of an OFDMA scheme, so that a performance of the system is prevented from being deteriorated.
Tue, 26 May 2015 08:00:00 EDTOne embodiment relates to a feedback receiver (FBR). The FBR includes a FBR signal input configured to receive a radio frequency (RF) signal, a first local oscillator (LO) signal input configured to receive a first LO signal having an LO frequency, and a second LO signal input configured to receive a second LO signal having the LO frequency. The second LO signal is phase shifted by approximately 90° relative to the first LO signal. FBR also includes a divider that induces a time-varying phase shift in the first and second LO signals while concurrently retaining a 90° phase shift between the first and second LO signals.