Abstract: Techniques are disclosed for measuring crosstalk between at least two communication channels of a communication system. A receiver of the system receives a signal over a given one of the communication channels from a transmitter of the system. The receiver correlates the received signal with a sequence of time-domain signals associated with another of the communication channels, and generates a measure of crosstalk between the given communication channel and the other communication channel based on the correlation between the received signal and the sequence of time-domain signals. The sequence of time-domain signals may be selected from a designated set of M-sequences.

Abstract: A multiple-input, multiple-output (MIMO) communication system is configured to perform user scheduling with reduced channel station information. The system includes multiple terminals and at least one base station configured to communicate with the terminals. The base station is operative to obtain channel vector magnitudes for respective ones of the terminals, to identify a subset of the terminals based on the channel vector magnitudes, to obtain channel vector phase information for the identified subset of terminals, and to utilize the channel vector phase information to control transmission to the identified subset of terminals. The system may be, for example, a multi-user MIMO system in which the multiple terminals comprise autonomous single-antenna terminals.

Abstract: In one aspect, a system is provided. In one embodiment, the system includes a plurality of wireless base stations that are located in a contiguous spatial coverage region of a cellular communication system. Each wireless base station that is configured to generate a coverage pilot beam to enable wireless mobile devices to set up spread spectrum wireless communication links with the generating wireless base station. The wireless base stations are configured to transmit data to the wireless mobile devices to cause a portion of the wireless mobile devices to reselect ones of wireless base stations for wireless communication links in a manner that reduces power load imbalances between the wireless base stations. The transmitted data is indicative of a set of shadow prices, wherein each of the wireless base stations is associated with a corresponding one of the shadow prices.

Abstract: An access node of a communication system is configured to generate denoised crosstalk estimates for respective channels of the system and to adjust power levels of signals transmitted over one or more of the channels based on the denoised crosstalk estimates. The access node obtains crosstalk estimates for the respective channels. The access node is configured to convert the crosstalk estimate for a given channel to a discrete transform domain, to substantially eliminate in the discrete transform domain one or more designated portions of the crosstalk estimate for the given channel, and to convert remaining portions of the crosstalk estimate for the given channel back from the discrete transform domain to obtain the corresponding denoised crosstalk estimate for the given channel. The access node may comprise one or more central offices of a DSL communication system.

Abstract: A wireless mobile device is configured to set up communications via wireless links with wireless base stations of a cellular communication system and to obtain information indicative of shadow prices of said wireless base stations via wireless transmissions. Each of the wireless base stations has a corresponding shadow price. The wireless mobile device is configured to make a select one of the wireless base stations for a wireless link with the wireless mobile device based on the information indicative of the shadow prices.

Abstract: Significant improvement in Raptor codes and punctured LDPC codes are obtainable by use of the invention. In both a transmission scheme for Raptor-encoded or LDPC-encoded information, a dynamic adjustment approach is employed. A fraction of a codeword or information frame is transmitted. A feedback signal is sent from the receiver to the transmitter indicating either 1) successful decoding, or 2) failure to decode and/or a feedback signal indicative of a statistical measure of transmission channel quality. If decoding fails, a further portion of the codeword or frame is sent. The intensity and/or size of the fraction is adjusted based on the feedback signal. In one embodiment, a specific range for probabilities employed in the encoding process for Raptor codes provides the ability to increase transmission throughput. Further it has been found that the advantageous Raptor codes are useful in noise conditions where even the improved punctured LDPC codes of the invention begin to degrade.

Abstract: A multi-channel processing module is arranged in series with multiple channels of a communication system. The processing module synchronizes downstream symbols among the channels, and synchronizes downstream symbols for at least a given one of the channels with upstream symbols for that channel. The synchronization of downstream symbols among the channels and the synchronization of downstream symbols for at least the given channel with upstream symbols for that channel are collectively achieved by adjusting downstream and upstream adjustable delay elements associated with respective downlink and uplink signal paths in the multi-channel processing module. The channels may comprise respective subscriber lines of a DSL communication system.

Abstract: It is possible to operate a wireless system, such as a CDMA system, in a more efficient manner by employing a statistical approach for setting power targets for reverse loop transmission. Unlike present methods for setting such targets a figure-of-merit quantity such as the frame error rate need not be measured to set the reverse loop transmission power for a wireless unit. Instead the target is set on a statistical basis established by sampling. Real time measurement of a quantity-of-merit is not required. A statistical approach produces among other things a decreased sensitivity to rapid changes in transmission conditions.

Abstract: At least one channel is joined to a group of active channels in a communication system by transmitting control signals to configure respective customer premises equipment (CPE) of the active channels into a joining mode of operation, and transmitting a joining signature sequence to CPE of the joining channel over a downstream data signal path of the joining channel. A central office (CO) or other access node of the system receives correlation results from respective active channel CPE, estimates crosstalk from the joining channel into the active channels based on the correlation results, configures a precoder based on the estimated crosstalk, and adds the joining channel to the group of active channels. The channels may comprise respective subscriber lines of a DSL communication system.

Abstract: A multiple-input, multiple-output (MIMO) communication system is configured to perform user scheduling and associated precoding. The system includes multiple terminals and at least one base station configured to communicate with the terminals. The base station is operative to obtain channel vectors for respective ones of the terminals, to select a subset of the terminals based on magnitudes of the respective channel vectors, to compute a precoding matrix using the channel vectors of the selected subset of terminals, and to utilize the preceding matrix to control transmission to the selected subset of terminals. The system may be, for example, a time-division duplex (TDD) multi-user MIMO system in which the multiple terminals comprise autonomous single-antenna terminals.

Abstract: Techniques are disclosed that efficiently obtain channel crosstalk estimates in DSL systems and other communication systems that may include unsynchronized channels. For example, a method includes obtaining a first set of estimated measures of crosstalk for a first portion of a plurality of communication channels over which data signals are to be transmitted from a transmitter to a plurality of receivers, and interpolating a second set of estimated measures of crosstalk for a second portion of the plurality of communication channels based on the first set of estimated measures of crosstalk. The first portion of the plurality of communication channels may be a subset of the plurality of communication channels and the second portion of the plurality of communication channels is a remainder of the plurality of communication channels. Each estimated measure of crosstalk may relate to at least one tone associated with at least one of the plurality of communication channels.

Abstract: Techniques are disclosed for compensating for crosstalk using adaptation of data signals transmitted over respective channels of a communication system. For example, a method includes the following steps. A first set of estimated measures of crosstalk is obtained for at least a selected portion of a plurality of communication channels over which data signals are to be transmitted from a transmitter to at least a selected portion of a plurality of receivers. A first set of data signals based on the first set of estimated measures of crosstalk is adapted to generate a first set of adjusted data signals. The first set of adjusted data signals is transmitted to corresponding ones of the plurality of receivers. A second set of estimated measures of crosstalk is obtained for the selected portion of the plurality of communication channels. A second set of data signals for transmission based on the second set of estimated measures of crosstalk is adapted to generate a second set of adjusted data signals.

Abstract: A method involves performing a plurality of acts. The acts include transmitting a first signal stream to a first channel of a multi-channel communications medium while transmitting a second signal stream to a different second channel of the medium. The second signal stream is substantially temporally correlated to the first signal stream. The method includes receiving an SINR measured at a receiver configured to receive signals from the first channel. The SINR is measured while the receiver received the first signal stream. The method includes determining a channel matrix element between the first and second channels or a ratio of said channel matrix element to a diagonal element of the channel matrix. The act of determining is based on the received SINR.

Abstract: Techniques are disclosed for compensating for crosstalk using adaptation of data signals transmitted over respective channels of a communication network. In one example, a method comprises the following steps. Data is transmitted to a communication network device via a communication line during a sequence of periods. For each period of the sequence of periods, a separate value of a measure of crosstalk that was measured at the communication network device is received, each value being an average of measurements at the device of measures of crosstalk for a plurality of communication network signal subcarriers. For each individual signal subcarrier of the plurality, a matrix is updated based on the received values, the matrix being configured to precode data transmissions to the communication network device over the individual signal subcarrier. The communication network may be a DSL system, the signal subcarriers may be DSL tones, and the measure of crosstalk may be a SINR value.

Abstract: Techniques are disclosed for measuring crosstalk between at least two communication channels of a communication system. A receiver of the system receives a signal over a given one of the communication channels from a transmitter of the system. The receiver correlates the received signal with a sequence of time-domain signals associated with another of the communication channels, and generates a measure of crosstalk between the given communication channel and the other communication channel based on the correlation between the received signal and the sequence of time-domain signals. The sequence of time-domain signals may be selected from a designated set of M-sequences.

Abstract: An apparatus includes a transmitter configured to transmit symbols to one or more receivers via a plurality of communication channels of a physical communication link. The transmitter is configured to estimate a phase of one or more off-diagonal elements of a channel matrix for the physical communication link based on values of signal-to-interference-plus-noise ratios at the one or more receivers.

Abstract: A multiple-input, multiple-output (MIMO) communication system is configured to perform user scheduling with reduced channel station information. The system includes multiple terminals and at least one base station configured to communicate with the terminals. The base station is operative to obtain channel vector magnitudes for respective ones of the terminals, to identify a subset of the terminals based on the channel vector magnitudes, to obtain channel vector phase information for the identified subset of terminals, and to utilize the channel vector phase information to control transmission to the identified subset of terminals. The system may be, for example, a multi-user MIMO system in which the multiple terminals comprise autonomous single-antenna terminals.

Abstract: A wireless mobile device is configured to set up communications via wireless links with wireless base stations of a cellular communication system and to obtain information indicative of shadow prices of said wireless base stations via wireless transmissions. Each of the wireless base stations has a corresponding shadow price. The wireless mobile device is configured to make a select one of the wireless base stations for a wireless link with the wireless mobile device based on the information indicative of the shadow prices.

Abstract: The scheduling of data transmissions for a CDMA system downlink or other type of communication network is implemented on a dynamic basis using a revenue-based policy. For a given transmission slot or other transmission interval, a maximum-rate user is identified from among a set of users requesting data transmissions, and a data transmission of the maximum-rate user is scheduled for the given interval. The maximum-rate user is identified based on application of coefficients of a revenue vector to corresponding feasible rates of the requesting users. The revenue vector is determined in an iterative manner using an adaptive algorithm which updates the revenue vector periodically to compensate for observed deviations between actual and target throughput, such that the deviations are reduced over time and the revenue vector converges to an optimal revenue vector.

Abstract: The scheduling of data transmissions in a CDMA system or other type of wireless communication system is implemented using a rate processor sharing approach in which user Quality of Service (QoS) requirements for forward link data transmission are converted into a rate and a corresponding violation probability, and an available system resource such as power is then divided among the users in accordance with the rates. For example, the approach may determine for each user i a rate Ri to be provided for user i with a probability 1−e−&dgr;i, where the &dgr;i are determined independently for each of the users. The system resource may be divided among the users in a manner which satisfies a linear relationship involving the rates and corresponding cost factors of the users. The portion of the system resource allocated to a given user may be fixed for a designated scheduling interval.