125results about "Echo effect reduction" patented technology

The present invention provides a synchronous demodulation apparatus of a base transceiver station in an Interim Standard-2000 (IS-2000) system, including a first synchronous demodulation unit, a received signal delay unit, an interference signal regeneration unit and a second synchronous demodulation unit. In comparison with an asynchronous demodulation apparatus used in an Interim Standard-95 (IS-95), it is possible for the inventive apparatus to improve a reception function approximately 3dB and ultimately increase the number of subscribers.

An echo cancellation device (ECD) comprises an echo canceller (EC) including a transfer function estimator (EST, H) and a subtractor (ADD) and a residual echo suppression device (G, ADD2). The residual echo suppression device (G) comprises a residual echo filter (G) having an adjustable filter function (g). This filter function (g) can be adapted to either remove from the subtractor output (TNE') the spectral characteristics relating to the reception signal (RFE) and/or to emphasize in the subtractor output signal (TNE') a background signal spectral content relating to the transmission signal (TNE). A noise generation means (NGM') can be provided at the output of the adaptable filter (G) for injecting a noise process in to the filter output signal (TNE') prior to a speech coding in a speech coder (COD). The noise process masks in the filter output signal a spectral content relating to the reception signal (RFE).

A voice activity detector that detects talkspurts in a given signal at a high accuracy, so as to improve the quality of voice communication. A frequency spectrum calculator calculates frequency spectrum of a given input signal. A flatness evaluator evaluates the flatness of this power spectrum by, for example, calculating the average of power spectral components and then adding up the differences between those components and the average. The resultant sum of differences, in this case, is used as a flatness factor of the spectrum. A voice/noise discriminator determines whether the input signal contains a talkspurt or not, by comparing the flatness factor of the frequency spectrum with a predetermined threshold.

A method and system for synchronizing location finding measurements in a wireless local area network (WLAN) provides a low cost mechanism for correcting location measurements within a WLAN location finding system. Multiple location receivers compute the time-of-arrival (TOA) of a reference transmitter signal, which is generally a beacon signal. The TOAs are collected and reported to a master unit that contains stored predetermined position information for the location receivers. The master unit computes the time-differences-of-arrival (TDOA) between multiple receivers and computes differences between the measured TDOAs and theoretical TDOAs computed in conformity with the predetermined position of each location receiver. The deviations between theoretical and measured TDOAs are collected in a statistical sample set and Kalman filters are used to produce a model of location receiver timebase offset and drift over multiple received beacon signals. The filter outputs are used to then either correct subsequent TDOA measurements for each location receiver, improving the accuracy of subsequent and/or prior TDOA measurements, or commands are sent to the location receivers to calibrate the timebases within the location receivers in order to improve the accuracy of subsequent TOA measurements.

A relay apparatus, terminal apparatus and relay method for relaying signals with a reduced scale of the apparatus, without temporally switching between transmission and reception and with reduced waste of time when relay is performed at the same frequency on a radio communication network on which bidirectional communication is performed. A radio reception section 202 outputs information signals to a switch 208, outputs relay control signals to a demodulation section 204 after subjecting predetermined radio reception processing. The demodulation section 204 demodulates a relay control signal. A relay control signal processing section 206 decides the possibility of relay of information signals and inquires, when the relay is possible, whether the terminal apparatus on the receiving side can receive this information signal or not. Furthermore, the relay control signal processing section 206 connects a switch 208 during the stored relay time. The switch 208 is connected only the information signals to be relayed are received under the control of a relay control section 2063.

A disclosed radio relay apparatus receives signals from a transmitter via multiple receive antennas and transmits relay signals derived from the received signals to a receiver via multiple transmit antennas. The apparatus includes a channel estimation unit configured to estimate a forward channel matrix H₁ representing radio channel characteristics between the transmitter and the radio relay apparatus and a loop channel matrix G representing interference occurring in the relay signals due to concurrently transmitting and receiving signals at the radio relay apparatus, a weight optimization unit configured to derive a canceling matrix C through iterative operations using the forward channel matrix H₁, the loop channel matrix G and a backward channel matrix H₂ representing radio channel characteristics between the radio relay apparatus and the receiver, and a feedback compensation unit configured to subtract a signal weighted in accordance with the canceling matrix C in a feedback path from a relay signal in a main signal path to adjust the relay signal.

The invention relates to an echo canceller, an echo cancellation method and the double-end talking detection system thereof, wherein, the echo canceller decodes a data stream from the network end into a far-end voice signal and extracts a short-time excitation signal as well as a linear prediction coding coefficient by utilizing a linear prediction decoder. Based on the linear prediction coding coefficient, the echo canceller carries out a decorrelation process to a residual signal by a decorrelation filter, and executes a normalized cross correlation process to the short-time excitation signal and the decorrelation residual signal by utilizing the double-end talking detector to generate the normalized cross correlation detection variable, hence, the echo canceller detects the existence of the double-end talking and then further controls the renewal of the self-adaptive filter. The invention is capable of detecting the existence of the double-end talking by the decorrelation process as well as the normalized cross correlation process to the far-end voice signal and the residual signal, thus obviously decreasing the calculation complexity of the double-end talking detection and the storage space consumption.

An apparatus is provided for a device-to-device, D2D, communication enabled user equipment, UE, comprising a processing section to determine, based on a signal received from another UE, a channel condition between the UE and the another UE; the UE to report the determined channel condition to an evolved Node B, eNB. The processing section is to initiate D2D communication based on a communication from the eNB, received in response to the report. Also, an apparatus is provided for a network element, comprising An input to receive a describing a channel condition between a first UE and a second UE; a processor to determine, based on the channel condition, whether or not D2D communication between the first UE and the second UE is to be enabled; and an output to output a result of the determination when the processor determines D2D communication is to be enabled. Related methods are also provided.

A multiple antenna wireless communication system using a DPD power amplifier and a method for controlling an amplitude of an input signal for a plurality of transmission paths of the DPD power amplifier are provided. The system includes a plurality of amplifiers, a plurality of couplers, a switch, a shared feedback path and a plurality of processors. The plurality of amplifiers amplifies an input signal directed to each of the transmission paths. The plurality of couplers couple amplified signals on respective transmission paths. The switch outputs at least one of the amplified signals coupled on the respective transmission paths. The shared feedback path provides the amplified signal output from the switch to a plurality of processors. The plurality of processors compare a feedback signal provided through the shared feedback path with the input signal and pre-distort the input signal such that the input signal and the amplified signal have a linear relation with each other.

Methods and devices are described for reducing transmit RF signal loss in a bi-directional RF transmit/receive system with a duplexer circuit. In one case a filter in a transmit path is used such as to reduce amplified noise in a receive frequency band.

An echo canceler for canceling echo components having a plurality of cascade-connected adaptive filters and a plurality of update control means. The echo canceler may further include an update control selective circuit for generating selective signals which enable or disable the update control means. Power values of opposite speech signals generated from the adaptive filters are used to control the updating of filter coefficients of the adaptive filters.

Systems and methods provide for controlling contention in a wireless network device. The systems and methods transmit a packet on a wireless network. If the transmission is not successful, then a contention window parameter is adjusted according to a fast backoff operation. If the packet transmission was successful and the current value of the contention window parameter is less than a threshold value then the contention window parameter is decreased according to a contention avoidance operation. If the packet transmission is successful and the current value of the contention window parameter is greater than the threshold value then the contention window parameter is decreased according to a slow start operation.

A flexible printed circuit board has first and second connection portions 18 and 19 where contacts are exposed and first and second path portions 16 and 17 where conductor patterns 11 are arranged that connect the contacts 11a and 11b of the first and second connection portions 18 and 19 together. The first and second path portions 16 and 17 are formed so as to have substantially symmetrical shapes with each other about a predetermined straight line, and the flexible printed circuit board is folded up along the straight line C1 and C2. Alternatively, a flexible printed circuit board has a conductor pattern 11 formed between first and second insulating sheets 12 and 13, and has a shielding conductor 14 fixed to the second insulating sheet 13. The flexible printed circuit board is folded up with the second insulating sheet 13 outside so that the conductor pattern 11 is enclosed inside the shielding conductor 14.

A cellular communication system has a number of cells covered by radio base stations communicating with communication device. The communication devices have a master timer for internally timing the communication devices relative to a timing of the cellular communication system. The master timer of a communication device is initially synchronized to a timing reference of a radio base station that provides the currently best communication link. Upon initial synchronization, the communication device determines and stores a first channel profile of received multi-path signals relative to the initial synchronization, and then enters a sleep mode. In the sleep mode a timing reference that controls the master timer is switched off. From the sleep mode, the communication device enters a receive mode and switches on its timing reference. The communication device then determines a second channel profile of received multi-path signals, and derives a timing offset signal from a best fit obtained by fitting the first channel profile to the second channel profile. Finally, the communication device re-synchronizes the master timer on the basis of the derived timing offset signal. The first and second channel profiles are characteristic in time to a particular configuration of radio base stations.

A method of controlling a wireless audio signal in order to avoid frequency interference between a display apparatus with a multi-view function and glasses with a function of receiving a wireless audio signal is provided.

The method of controlling a wireless audio signal in a wireless audio signal transmitting device includes: pairing with a wireless audio signal receiving device using a first frequency band; detecting frequency interference by an external device other than the paired wireless audio signal receiving device; scanning a frequency when frequency interference is detected; determining whether a frequency change is needed using information related to the scanned frequency; and changing an audio signal transmitting frequency when frequency change is needed.

A method of synchronising a wireless communication unit in a communication system, the method comprising at said wireless communication unit the steps of: monitoring transmissions from a communication system and processing (400) frequency and/or timing information from the communication system. The method further includes the steps of transmitting (404) frequency and/or timing information by said wireless communication unit; receiving and processing (406) said frequency and/or timing information transmitted by said wireless communication unit at a receiving portion of said wireless communication unit. The wireless communication unit then compares frequency and/or timing information transmitted from the communication system to that transmitted by said wireless communication unit; and synchronises said wireless communication unit if said comparison step does not yield a match. A wireless communication unit and a communication system are also provided.

A multiple channel steered spatialized signal is generated from a signal input modified according to respective spatialization gain functions to generate a plurality of audio channels. An echo cancellation signal is applied to a return path using a combined spatialization and echo path estimate. The estimate is derived from the gain functions applied to the respective channels. When the gain functions applied in the respective channels are changed, for instance to represent a different apparent position of the sound source, a new estimate of the echo paths is generated, based on a previous estimate of the echo path and on the new gain functions.

A noise detector extracts pulse noise. On the basis of the extracted pulse noise, a threshold generator generates a threshold. A gate pulse generator compares the pulse noise with the threshold and, when the waveform of the pulse noise exceeds the threshold, generates a gate pulse. During the gate pulse is generated, a gate inhibits outputting of a demodulated signal of a detector, and during the period, interpolates the signal to output the resultant, thereby eliminating pulse noise from an output signal of the gate.