Abstract: Operation of a digital subscriber line system in a power saving quiescent mode is described. A quiescent mode (Q-mode) is entered into from a steady-state or normal operation mode in which payload data is transmitted when criteria indicates that the transmitter has stopped transmitting payload data for a certain time period but that the current transmission session has not ended. A Q-mode signal is generated that uses constellation points that are used in the payload carrying state. The peak-to-average ratio (PAR) of the signal is also minimized by a PAR minimization method to find a combination of these constellation points satisfying a PAR threshold.

Abstract: Signals are developed for use in a wireless system with multiple transmit and multiple receive antennas so that even in the face of some correlation the most open-loop capacity that can be achieved using a substantially open-loop system with a channel of that level of correlation is obtained. In accordance with the principles of the invention, the signals transmitted from the various antennas are processed so as to improve their ability to convey the maximum amount of information. More specifically, the data to be transmitted is divided into M+1 substreams, where M is the number of transmit antennas. Each transmit antenna is supplied with a combination signal that is made up of a weighted version of a common one of the substreams and a weighted version of a respective one of the substreams that is supplied uniquely for that antenna, so that there are M transmit signals. A receiver having N antennas receives the M transmit signals as combined by the channel and reconstitutes the original data therefrom.

Abstract: In a MIMO system the signals transmitted from the various antennas are processed so as to improve the ability of the receiver to extract them from the received signal even in the face of some correlation. More specifically the number of bit streams that is transmitted simultaneously is adjusted, e.g., reduced, depending on the level of correlation, while multiple versions of each bit stream, variously weighted, are transmitted simultaneously. The variously weighted versions are combined to produced one combined weighted signal. The receiver processes the received signals in the same manner as it would have had all the signals reaching the receive antennas been uncorrelated.

Abstract: SELP techniques that provide an accurate estimate of the length of a transmission medium (e.g., subscriber loop in a DSL system) are disclosed. A probe signal is transmitted over the transmission medium at one or more frequencies. A reflected version of the probe signal is then received. Transmission medium impedance is determined based on the ratio of the reflected version of the probe signal and the transmitted probe signal. An estimate of transmission medium length is determined by comparing its impedance to a plurality of predetermined impedances, each of which is associated with a transmission medium having known length. Thus, the length of the systems transmission medium is identified. The transmission medium impedance can also be used to identify the presence of load coils and short circuits in the transmission medium.

Abstract: Signals are developed for use in a wireless system with multiple transmit and multiple receive antennas so that even in the face of some correlation the most open-loop capacity that can be achieved using a substantially open-loop system with a channel of that level of correlation is obtained. In accordance with the principles of the invention, the signals transmitted from the various antennas are processed so as to improve their ability to convey the maximum amount of information. More specifically, the data to be transmitted is divided into M+1 substreams, where M is the number of transmit antennas. Each transmit antenna is supplied with a combination signal that is made up of a weighted version of a common one of the substreams and a weighted version of a respective one of the substreams that is supplied uniquely for that antenna, so that there are M transmit signals. A receiver having N antennas receives the M transmit signals as combined by the channel and reconstitutes the original data therefrom.

Abstract: Single Ended Line Probing (SELP) techniques for devices having transformerless hybrid circuits are disclosed. These SELP techniques provide an accurate estimate of the length of a transmission medium (e.g., subscriber loop in Digital Subscriber Line (DSL) system) by computing a transfer function that accounts for the characteristics of the transformerless hybrid circuit and the transmission medium, and relating the transfer function to the length of the transmission medium at one or more frequencies.

Abstract: Signals are developed for use in a wireless system with multiple transmit and multiple receive antennas so that even in the face of some correlation the most open-loop capacity that can be achieved using a substantially open-loop system with a channel of that level of correlation is obtained. In accordance with the principles of the invention, the signals transmitted from the various antennas are processed so as to improve their ability to convey the maximum amount of information. More specifically, the data to be transmitted is divided into M+1 substreams, where M is the number of transmit antennas. Each transmit antenna is supplied with a combination signal that is made up of a weighted version of a common one of the substreams and a weighted version of a respective one of the substreams that is supplied uniquely for that antenna, so that there are M transmit signals. A receiver having N antennas receives the M transmit signals as combined by the channel and reconstitutes the original data therefrom.

Abstract: A Single Ended Line Probing (SELP) technique using combined Frequency Domain Reflectometry (FDR) and Time Domain Reflectometry (TDR) for characterizing a transmission medium (e.g., DSL) is disclosed. FDR is used to detect one or more reflectors (e.g., short, load coil, bridge tap) in the transmission medium. TDR is then used to determine the location of the reflectors in the transmission medium. In one embodiment, a wide band periodic probing signal is used to probe the transmission medium for reflectors. In another embodiment, gauge information can be used to increase the valid range of the combined FDR/TDR SELP technique.

Abstract: Techniques that allow SHDSL-based systems to share the same transmission line with low frequency voice services such as POTS are disclosed.

Abstract: Single Ended Line Probing (SELP) techniques for devices having transformerless hybrid circuits are disclosed. These SELP techniques provide an accurate estimate of the length of a transmission medium (e.g., subscriber loop in Digital Subscriber Line (DSL) system) by computing a transfer function that accounts for the characteristics of the transformerless hybrid circuit and the transmission medium, and relating the transfer function to the length of the transmission medium at one or more frequencies.

Abstract: SELP techniques that provide an accurate estimate of the length of a transmission medium (e.g., subscriber loop in a DSL system) are disclosed. A probe signal is transmitted over the transmission medium at one or more frequencies. A reflected version of the probe signal is then received. Transmission medium impedance is determined based on the ratio of the reflected version of the probe signal and the transmitted probe signal. An estimate of transmission medium length is determined by comparing its impedance to a plurality of predetermined impedances, each of which is associated with a transmission medium having known length. Thus, the length of the systems transmission medium is identified. The transmission medium impedance can also be used to identify the presence of load coils and short circuits in the transmission medium.

Abstract: The signal to interference and noise ratio (SINR) of wireless systems can be improved, if not optimized, by determining operating parameters used by the base station to substantially simultaneously control the transmit beam patterns that are each formed to establish a communication channel between a base station and a respective one of the wireless terminals as a function of received channel information from at least two of the wireless terminals. In an exemplary embodiment of the invention, the weight vectors and the power allocation employed by a base station are determined by the base station using information supplied by at least each of the wireless terminals served by the base station, and potentially from wireless terminals served by other base stations, e.g., in neighboring cells to the cell served by the base station, the information from the other cells being supplied via the neighboring cell base stations using inter-base-station communication, e.g., a wire line connection.

Abstract: In a mobile cellular communications system power control and space-time diversity are applied in combination to the uplink and downlink. In the uplink, mobile powers and equalization/diversity combining vectors at base stations are, calculated jointly, with the result that the mobile transmitted power is minimized, while the Signal to Noise Ratio (SNR) at each link is maintained above a threshold. In the downlink, a multitap transmit diversity strategy adjusts the transmit weight vectors with the result that the SNR at each mobile is set to a specified value. The combination of power control and space-time diversity apply to networks with fading channels, including networks in which the number of cochannels and multipaths are larger than the number of antenna elements. The invention achieves the optimal solution for the uplink that minimizes the mobile power, and achieves a feasible solution for the downlink if there exists any.

Abstract: Techniques are described for reducing the effect of crosstalk in multiple input multiple output (MIMO) DSL communications system, having a transmitter processor with N transmitters coupled to a receiver processor having L receivers. A number of signals are received by each receiver, including the intended signal and a number of interference signals. Each of the signals received by a receiver is weighted with a weight to produce a number of weighted signals. One or more of the weighted signals are combined to produce one or more estimated transmitted signals. The effect of each interference signal can effectively be eliminated.

Abstract: The performance of a CDMA receiver employing multiple antennas can be improved, in accordance with the principles of the invention, by directly combining together appropriately weighted signals from the rake receiver fingers that are being supplied by at least two different antennas, i.e., they are in two different receiver modules each of which is what would have been called in the prior art a rake receiver module but without the associated summer, to develop an output with at least as good, and more likely an improved, signal to interference and noise ratio (SINR), as compared to the prior art rake receiver architecture. By doing so the functionality of the beamforming coefficients and the rake multiplier vectors is joined, and it is possible to optimize the rake receiver performance.

Abstract: An algorithm is created and applied to reconstruct the wavelet coefficients of an image from the Radon transform data for use in computed tomography, with a disclosed method that uses the properties of wavelets to localize the Radon transform such that a local region of the cross section of a body can be reconstructed using almost completely local data to significantly reduce the amount of exposure and computations in X-ray tomography. The described algorithm is based on the observation that for some wavelet bases with sufficiently many vanishing moments, the ramp-filtered version of the scaling function as well as the wavelet function has extremely rapid decay, with the variance of the elements of the nullspace is being negligible in the locally reconstructed image.