Abstract: The present invention provides an interference controller and method for limiting in one cell the effect of interference generated by other cells of a wireless telecommunications system, each cell of the wireless telecommunications system having a central terminal and a plurality of subscriber terminals, communication between a central terminal and a subscriber terminal being arranged to occur over a wireless link, and a plurality of code division multiplexed channels being provided within a single frequency channel to enable data items pertaining to a plurality of wireless links to be transmitted simultaneously within different code division multiplexed channels of said single frequency channel.

Abstract: A crosstalk canceller system is disclosed for a transceiver bank, which has one or more transmitters and one or more receivers, for cancelling crosstalk between signals associated with different communications channels having overlapping frequency bands. In a simplified embodiment, the system includes a crosstalk canceller (CC) connected between transmit and receive connections to receive a transmit signal and receive signal, respectively, associated with different communications channels. The CC produces a cancellation signal and passes the cancellation signal to an adder. The adder combines the cancellation signal with the receive signal to generate an enhanced receive signal, which is communicated to the receiver and also back to the CC. The enhanced receive signal is characterized by less crosstalk as compared to the original receive signal.

Abstract: This invention reduces near-end crosstalk between identical discrete multi-tone (DMT-type) modems by introducing the following modifications to modems at a central office or a subscriber premises. The modifications include: a mechanism for aligning the frames of all modems at the central office (CO), a mechanism for aligning the frames transmitted by the subscribers' modems with the frames received by those modems, and lengthening the DMT frame to include a cyclic prefix. The cyclic prefix to a frame has been made longer than twice the maximum round-trip delay, that is, the delay between the central office and the most distant subscriber to be served. By making adjacent DMT carrier frequencies be orthogonal to each other, the aforementioned modifications will reduce both Near End Cross-Talk (NEXT) and Leakage-Excited Cross-Talk (LEXT). These benefits apply to modems at both the central office (CO) and subscriber ends of the communication path (for example, a high capacity twisted-pair wire).

Abstract: A digital cordless telephone system can prevent control signals transmitted from a plurality of base stations from interfering with each other. In a digital cordless telephone system wherein a communication signal is transmitted among it and terminal stations by transmitting digital data through a predetermined channel and a communication among it and the terminal stations is controlled by a control channel different from the predetermined channel, data in a slot arrangement is used as a control signal, the control signal of the slot arrangement is intermittently transmitted at a constant interval, and a transmission at every constant interval is randomly extinguished.

Abstract: A method and apparatus for monitoring the performance of an echo canceler within a telephone communications network is disclosed. In accordance with the method and apparatus of the present invention, an embedded echo-cancellation performance monitoring circuit comprises three separate units, namely, a test data injection unit, an echo path simulator unit, and a test data extraction unit. The test data injection unit is utilized to inject test data into a serial data stream intended for an echo canceler. The echo path simulator unit is utilized to simulate an echo path by attenuating the test data in the serial data stream and to loop the test data in the serial data stream back to the echo canceler. The test data extraction unit is utilized to extract the test data from a send-out data stream exiting from the echo canceler.

Abstract: A method of adjusting the sensitivity of a receiver requires the association of a network address of a remote network device, such as a computer, with a first port of a multiport network device, such as a switch. The reception of the network address of the remote network device at a second port of the multiport network device indicates the possible occurrence of a cross-talk condition between networks coupled to the first and second ports. Accordingly, the sensitivity of a receiver associated with the second port is reduced in an attempt to reduce the sensitivity thereof to a point at which cross-talk signals, generated as a result of the cross-talk condition between networks coupled to the first and second ports, are no longer detected. The sensitivity of the receiver may be reduced by increasing a noise threshold level below which signals are not detected.

Abstract: A central office xDSL modem pool has N logical xDSL modems. Each modem consists of a transmitter part and a receiver part and is connected to a twisted pair subscriber loop. A central office clock synchronizes the modem transmitters. A reverse channel near-end crosstalk (NEXT) canceller bank is implemented within the modem pool. The NEXT canceller bank has N NEXT cancellers corresponding to the N MDSL modems. Each canceller has N adaptive filters of size M. Outputs of all N adaptive filters are combined to form the NEXT cancellation signal for the corresponding modem. Each adaptive filter is adapted according to the error signal between the received signal and the NEXT cancellation signal and the corresponding transmit signal as the correlation vector.

Abstract: An apparatus or system for data communications that provides crosstalk cancellation is disclosed. The apparatus or system removes crosstalk interference (e.g., NEXT interference) from received signals on a given line by adaptively estimating the crosstalk interference induced by certain other of the lines having interfering transmissions and by canceling the crosstalk interference using the estimated crosstalk interference from the certain other of the lines. The invention is useful for high speed data transmissions where crosstalk interference can be a substantial impediment to proper reception of data. In particular, the invention is useful for VDSL and ADSL data transmissions using multicarrier modulation (e.g., DMT), wherein transmission frames for all lines are synchronized but the duration of the direction of transmission can vary due to differing frames.

Abstract: N signals are transmitted from each of N transmitting units to a receiving unit every signal transmission cycle (N.gtoreq.2). In this case, N signal transmitting periods of N I-th signals and (N-1) I-th transmission short pausing periods for each of the I-th transmitting units are alternately placed in each of I-th signal grouping periods (1.ltoreq.I.ltoreq.N), and an I-th transmission long pausing period follows each of the I-th signal grouping periods to set one signal transmission cycle composed of one I-th signal grouping period and one I-th transmission long pausing period for each of the I-th transmitting unit. A time length of each first transmission short pausing period is equal to that of the signal transmitting period, a time length of each I-th transmission short pausing period is (2N+2I-5) times as long as that of the signal transmitting period, and a time length of the signal transmission cycle is 4N(N-1) times as long as the signal transmitting period.

Abstract: A system for configuring a process control system, e.g., a Fieldbus network, having intelligent field mounted devices coupled to a data communications bus. A software representation of the process control system to be configured is first designed on a computer. Using the system, a user selects representations of the various field mounted devices to be included in the actual control system. The user then specifies which function blocks of each field mounted device are to be used and how those function blocks are to be linked. The computer is then coupled to the communications bus of the actual control system via an interface device and the configuration and link data are downloaded to the field mounted devices of the control system. The computer can act as a bus master of the communications bus of the control system with the field mounted devices acting as slaves.

Abstract: Interference on a differential signal received at a first input to a digital data system processor is minimised or cancelled by summing a weighted portion of a local field signal with the differential signal. The local field signal may be a common-mode signal from the same line as the differential signal received at a second input. Weight may be a complex weight which shifts the local field signal in amplitude and phase. A weight control signal is derived from a comparison processor which compares the processed outputs of signal processors. Signal processors are preferably Discrete Multi-tone processors. Several iterations of this technique may be performed to establish an accurate weighting value.

Abstract: The disclosure relates to the transmission of data by packets on carrier frequencies with spreading and de-spreading of the data elements. In order to reduce the risks of overlapping among packets sent out by different transmitters, each packet to be transmitted is designed according to the characteristics of frequency spreading and/or code spreading of a common standard packet, constituted by successive segments all orthogonal to one another, the first segment comprising a header designed for identification. At reception the header, when it is found, activates the processing of the corresponding packet with de-spreading as a function of the characteristics of the spreading of the standard packet as they are known to the transmitter.

Abstract: A method and system for reducing co-channel interference (CCI) in multiple access communication by providing complete or partial cancellation of a mixed CCI interfering signal in a system base station. An exemplary system includes first and second base stations communicating with users in first and second cells, respectively. The first base station transmits a downlink signal to a user in the first cell. The downlink signal is also a mixed CCI interfering signal in that it interferes with reception of an uplink signal in the second base station. A cancellation signal representative of the interfering signal is supplied along a transmission path from the first base station to the second base station. The second base station utilizes the cancellation signal to reduce the effect of the interfering signal on a received composite signal by, for example, combining the cancellation signal or a suitably processed version thereof with the received composite signal.

Abstract: A CATV interference cancellation system reduces the presence of undesirable narrowband interference that corrupts return signal transmissions. The cancellation system first acquires a reference signal that contains components related to the interference present in the return signal. The reference signal is processed to derive estimates of the interference components appearing in the return signal and a cancellation signal is generated. The interference cancellation signal is then combined with the return signal, thereby reducing the interference components present in it. The interference cancellation system is deployed at a CATV headend and time division multiple access techniques (TDMA) are used for return transmission. The reference signal is derived from monitoring time slots within a TDMA frame that contain predetermined transmission data. Preferably the predetermined data is the absence of data resulting in an idle time slot.

Abstract: A spread-spectrum code division multiple access interference canceler for reducing interference in a direct sequence CDMA receiver having N chip-code channels. The interference canceler includes a plurality of correlators or matched filters, a plurality of spread-spectrum-processing circuits, subtracting circuits, and channel correlators or channel-matched filters. Using a plurality of chip-code signals, the plurality of correlators despreads the spread-spectrum CDMA signal as a plurality of despread signals, respectively. The plurality of spread-spectrum-processing circuits uses a timed version of the plurality of chip-code signals, for spread-spectrum processing the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal. For recovering a code channel using an i.sup.

Abstract: A frequency-selective interference signal detecting apparatus and method thereof generates as many tone signals as the number of a frequency-selective interference signals at the transmission side of a transmission system and one tone signal corresponding to an optional frequency at an occupied band frequency of the transmission system, transmits all generated tone signals to a receiving side of the transmission system through the transmission channel selectively, computes an SNR with regard to each tone signal by receiving these tone signals at the receiving side, compares the calculated SNR with a preestablished reference value, detects whether or not each of the frequency-selective interference signals exist, provides the degree of such interference, and makes several frequency-selective interference signals detectable so as to raise transmission efficiency of a data signal in the transmission system.

Abstract: A receiver performs rapid adaptive interference canceling for use in despreading multiple CDMA channels sharing the same RF front end. The receiver includes a buffer (22) for providing for overlapping time samples and rate adaptation, a windowing function (24) for improving interference rejection capability and a FFT (26) for calculating the input power spectrum. The receiver further includes a circuit (28, 30) to whiten the input power spectrum. The whitened power spectrum is multiplied (32) against the frequency domain version of different spreading sequences and the inverse FFT (40) of the product is performed. The output of this inverse FFT is buffered (44) to provide multiple despread output channels, with a plurality of code phases for further processing.

Abstract: A DS3 level access, monitor and test system for a telephone network. The system provides selective, and hitless, bit overwrite in any of the embedded DS1, DS0 and subrate channels in a DS3 signal. Multiple DS0 and subrate channels can be tested via the asynchronous time slot interchange in conjunction with the recombiner of the present invention. A second embodiment of the invention partitions the system into a base subsystem, a communications link and a remote subsystem, collectively referred to as a distributed architecture system. The distributed architecture system provides all of the performance monitoring and testing capabilities of the existing access system. The distributed architecture system provides a mechanism to transport a plurality of asynchronous and rate independent signals across the link to permit remote testing of digital and voice DS0 frequency circuits. In the preferred embodiment, the link that connects the base to the remote system is a standard DS1 channel.

Abstract: A method and apparatus for (1) transmitting large amounts of data between a least a first and second station over a twisted pair, (2) reducing cross talk in a network using carrierless amplitude modulation and phase modulation encoding (CAP) with independent data clock source at each station, (3) providing a relatively simple and fast data detection apparatus, (4) maintaining synchronization between stations during idle periods while minimizing cross talk, (5) providing a technique to allow filters to be trained during idle periods, and (6) providing a technique which allows automatic gain control to be used with CAP. Particular signalling symbols are associated with each of the following conditions: (1) idle state, (2) preamble, (3) start of frame detection, (4) test condition, (5) each possible combination of five binary bits representing 32 different data symbols, and (6) jam condition. For example, a unique pair of the four inner most points on the CAP 36 constellation are used for indicating idle mode.

Abstract: A source transmitted signal is cancelled at the receiver associated with the transmitter, so that the desired received signal can be extracted from a composite received signal, the composite received signal consisting of the source signal relayed from the relay station along with the desired received signal from the other user in the pair, plus additive noise. The invention takes advantage of the fact that each of the users knows a priori the exact structure of its source transmitted signal and can estimate the channel characteristics between the relay station and itself.