Abstract: A method for communication includes receiving a spatially-multiplexed signal using multiple receivers to produce multiple respective received signals. The spatially-multiplexed signal includes multiple simultaneously-transmitted symbols, which are selected from respective sets of constellation symbols, each constellation symbol representing a respective set of values of a group of data bits. Combinations of the constellation symbols are traversed iteratively. Each combination includes one constellation symbol from each of the sets of the constellation symbols and represents N data bits. The traversed combinations are searched for a combination that matches the received signals. During traversal of the combinations, at least 2N measures of likelihood regarding the values of the data bits represented by each traversed combination are accumulated. The accumulated measures of likelihood are processed to produce soft bit metrics.

Abstract: A method for communication includes allocating, in a multiple-access communication system (20) that uses multiple subcarriers, first subcarriers to a first communication terminal for transmitting first data, and second subcarriers to a second communication terminal for transmitting second data. The first communication terminal is assigned to modulate the first data onto at least some of the first subcarriers using a first multi-carrier modulation scheme, to produce a first signal. The second communication terminal is assigned to modulate the second data onto at least some of the second subcarriers using a second multi-carrier modulation scheme, which has a reduced peak-to-average power ratio (PAPR) relative to the first multi-carrier modulation scheme, to produce a second signal. Simultaneous communication is carried out with the first and second communication terminals by simultaneously receiving the first and second signals over the first and second subcarriers.

Abstract: A method for communication includes receiving a spatially-multiplexed signal using multiple receivers to produce multiple respective received signals. The spatially-multiplexed signal includes multiple simultaneously-transmitted symbols, which are selected from respective sets of constellation symbols, each constellation symbol representing a respective set of values of a group of data bits. Combinations of the constellation symbols are traversed iteratively. Each combination includes one constellation symbol from each of the sets of the constellation symbols and represents N data bits. The traversed combinations are searched for a combination that matches the received signals. During traversal of the combinations, at least 2N measures of likelihood regarding the values of the data bits represented by each traversed combination are accumulated. The accumulated measures of likelihood are processed to produce soft bit metrics.

Abstract: A method for communication includes allocating, in a multiple-access communication system (20) that uses multiple subcarriers, first subcarriers to a first communication terminal for transmitting first data, and second subcarriers to a second communication terminal for transmitting second data. The first communication terminal is assigned to modulate the first data onto at least some of the first subcarriers using a first multi-carrier modulation scheme, to produce a first signal. The second communication terminal is assigned to modulate the second data onto at least some of the second subcarriers using a second multi-carrier modulation scheme, which has a reduced peak-to-average power ratio (PAPR) relative to the first multi-carrier modulation scheme, to produce a second signal. Simultaneous communication is carried out with the first and second communication terminals by simultaneously receiving the first and second signals over the first and second subcarriers.

Abstract: A terminal (24) for use in a wireless network (20) includes a radio frequency (RF) receiver (30), which is configured to receive and downconvert a RF signal. The RF signal includes downlink frames, each downlink frame including at least an allocation zone followed by a data zone. The allocation zone contains an indication of a time allocation in the data zone during which downlink data will be transmitted to the terminal. An analog/digital (A/D) converter (36) converts the output signal from the RF receiver into a stream of digital samples. A digital processing circuit (40, 52, 54, 56) processes the digital samples so as to identify the time allocation and to recover the downlink data transmitted during the identified time allocation, while shutting down the RF receiver during at least one interval during the downlink frame that is outside the identified time allocation.

Abstract: A novel and useful baseline wander correction mechanism for use with transformer coupled baseband communication receivers. Parametric estimation of the transformer model is used estimate and cancel the baseline wander effect. A parametric model is used to model the baseline wander impairment created by the transmitter and receiver transformers as a high pass filter having an exponential decay parameter alpha. A correction signal for both the far end and echo signal paths are calculated and summed to generate a total correction signal. The total correction signal is partitioned into an analog correction signal that is applied to the analog portion of the communications receiver and into a digital correction signal that is similarly applied to the analog portion of the communications receiver.

Abstract: The present invention provides an encoding method and a class of decoding methods that provide methods for high throughput and high robustness digital communications over channels that are contaminated by impulse noise, as well as white and colored additive noise (noise that is characterized by heavy-tailed distribution), phase noise and signal fading.

Abstract: A system is provided to automatically estimate performance of a receiver for receiving input signals, the input signals having a carrier frequency and a baud rate, from a channel in a communication system and the effect of highly correlated noise cancellation on performance of the receiver, while no active transmission is occurring on the channel, comprising: a digital front end in the receiver for receiving samples of the input signals; a predictor coupled to the digital front end for predicting highly correlated noise in a second sample of the input signal; and a subtraction unit coupled to the predictor for subtracting the predictor output from the second sample to determine residual noise in the second sample. Other systems and methods are disclosed.

Abstract: A method for communication includes allocating, in a multiple-access communication system (20) that uses multiple subcarriers, first subcarriers to a first communication terminal for transmitting first data, and second subcarriers to a second communication terminal for transmitting second data. The first communication terminal is assigned to modulate the first data onto at least some of the first subcarriers using a first multi-carrier modulation scheme, to produce a first signal. The second communication terminal is assigned to modulate the second data onto at least some of the second subcarriers using a second multi-carrier modulation scheme, which has a reduced peak-to-average power ratio (PAPR) relative to the first multi-carrier modulation scheme, to produce a second signal. Simultaneous communication is carried out with the first and second communication terminals by simultaneously receiving the first and second signals over the first and second subcarriers.

Abstract: A novel and useful mechanism for the mitigation of baseline wander from wired networks such as Ethernet. A high pass filter is inserted before the analog to digital converter having a pole within the range of 5-12 MHz. This eliminates the need for any other baseline wander removal schemes, whether analog or digital and provides sufficient performance in terms of noise budget.

Abstract: A novel and useful baseline wander correction mechanism for use with transformer coupled baseband communication receivers. Parametric estimation of the transformer model is used estimate and cancel the baseline wander effect. A parametric model is used to model the baseline wander impairment created by the transmitter and receiver transformers as a high pass filter having an exponential decay parameter alpha. A correction signal for both the far end and echo signal paths are calculated and summed to generate a total correction signal. The total correction signal is partitioned into an analog correction signal that is applied to the analog portion of the communications receiver and into a digital correction signal that is similarly applied to the analog portion of the communications receiver.

Abstract: A method is provided for automatically improving throughput of an active channel in a communication system comprising: receiving input from one or more modules that identify and characterize impairments in the active channel; monitoring the input to track changes in the impairments; and changing channel parameters to improve throughput on the channel based on the changes in the impairments. Other systems and methods are disclosed.

Abstract: A method is provided for automatically improving throughput of an active channel in a communication system comprising: receiving input from one or more modules that identify and characterize impairments in the active channel; monitoring the input to track changes in the impairments; and changing channel parameters to improve throughput on the channel based on the changes in the impairments. Other systems and methods are disclosed.

Abstract: A novel and useful mechanism for shutting down very small canceller taps that have little influence on the output of the canceller. Disabling or completely disabling these taps results in a significant reduction in power consumption of the circuit incorporating the canceller. Shutting down very low valued canceller taps also results in reduced least mean square (LMS) noise caused by the jittering of the smaller taps of the canceller. Several methods are provided that determine the number and location of the taps to be shutdown. The mechanism of the invention is operative to shut down canceller taps that are lower than a predetermined threshold. Methods include comparing each individual tap to a threshold, comparing an average of each tap to a threshold, comparing groups of taps to a threshold and comparing an average of groups of taps to a threshold. Taps or groups of taps are smaller than the threshold are shutdown thus reducing the power consumption of the canceller.

Abstract: A method is provided to provide data to automatically estimate channel performance in a communication system if a different order constellation is used comprising the steps of: receiving an input signal from the channel; passing the input signal to a slicer having an output signal; determining signal noise by taking the difference between the input signal and output signal; identifying a beginning of a noise event when the signal noise is greater than a predefined first threshold; identifying an end of a noise event when the signal noise is less than a predefined second threshold; and providing for output the beginning of the noise event and the end of the noise event. Other systems and methods are disclosed.

Abstract: The present invention comprises aggregating a plurality of physical channels to a single logical channel, a scalable virtual channel (SVC). This may be implemented in a point to multipoint communications system. The present invention enables a variety of receivers, some receivers being able to receive only one physical channel, and other receivers being able to receive a plurality of physical channels as a SVC, with at least one same channel being used for both types of receivers.

Abstract: A method is provided for automatically optimizing parameter selection in a communication system having one or more channels for transmitting and receiving signals by the steps of: receiving a signal from a channel; characterizing impairments in the channel while gathering statistics using the received signal; analyzing the impairments to obtain recommendations for parameter modifications for improved performance; and modifying the parameters based on the recommendations. Other systems and methods are disclosed.

Abstract: A method is provided to automatically identify noise events in a channel of a communication system comprising the steps of: receiving an input signal from the channel; determining the mean energy of the input signal; determining the recent energy of the input signal; identifying a beginning of the noise event when the recent energy is greater than the product of the mean energy and a predefined first threshold; identifying an end of a noise event when the recent energy is less that the product of the mean energy and a predefined second threshold; and providing for output the beginning of the noise event and the end of the noise event. Other systems and methods are disclosed.

Abstract: A method is disclosed for providing data for automatically estimating channel performance if different parameters of a Reed-Solomon (RS) code are used in a communication system while transmission is occurring in the communication system without changing the current Reed-Solomon (RS) code parameters.

Abstract: A method is provided for reduced interference between S/CDMA channels (chips) by selecting a first sequence of spreader functions for a first channel, and selecting a second sequence of spreader functions for a second channel, wherein said second sequence is non-overlapping with and spaced from first said sequence.