Abstract: A low-complexity and low-latency method and apparatus in multicarrier communication systems is used for protection and transmission of the side information related to peak-to-average power ratio (PAPR) reduction. The side information is encoded by an error-correction code and transmitted through a plurality of reserved sub-carriers. Modulation of the coded side information over the reserved sub-carriers is performed separately without re-performing data modulation. Therefore, the invention dramatically reduces implementation complexity. Determination of the related parameters for PAPR reduction can be based on the PAPR level of the data modulated signal with slight degradation in PAPR reduction performance or that of level of the transmitted signal with no degradation in PAPR reduction performance.

Abstract: A soft symbol decoder for use in a multiple input multiple output (MIMO) and OFDM (orthogonal frequency division multiplexing) system. The decoder generates soft symbol values for a digital signal that represents a number of source bits. The source bits are transmitted as symbols in corresponding to points in a signaling constellation. Soft metrics are determined by searching for all possible multi-dimensional symbols that could have been transmitted. The method includes transmitting a sample of the multi-dimensional symbol using K transmit antennas. The multi-dimensional symbol is represent-able as a complex, K-dimensional vector x. Each vector component of vector x represents a signal transmitted with one of the K transmit antennas. After transmission through a communication channel, a sample corresponding to the transmitted sample is received. The received sample is represented by a complex, N-dimensional vector y, where N is the number of receive antennas in the MIMO system.

Abstract: In a digital receiver for receiving COFDM modulated television signals or the like, consecutive samples are compared with a detection threshold and the number of samples having amplitudes greater than the threshold is determined. This is compared with a further threshold and, if the number of such samples exceeds the further threshold, affected samples are blanked to zero. Similarly, an automatic gain control loop is disabled when the samples are blanked. A demodulator forms the difference in phase of pilot carriers from symbol to symbol. If the variance of the phase differences exceeds an averaged value, this indicates the presence of impulsive noise and is used to inhibit signal correction techniques within the demodulator. Noise energy is thus reduced and propagation of effects resulting from impulsive noise from symbol to symbol is substantially reduced.

Abstract: A communication system is disclosed that allows high data-rate transmission of data between components. N-bit parallel data is transmitted in K-frequency separated channels on the transmission medium so as to fully take advantage of the overall bandwidth of the transmission medium. As a result, a very high data-rate transmission can be accomplished with low data-bit transmission on individual channels.

Abstract: A system which allows multiple senders to asynchronously transmit identification codes via a common communication channel (e.g., RF) to enable a central monitor to identify the presence (or absence) of each sender within the monitor's detection zone. Each sender is configured to repeatedly transmit a uniquely encoded identification frame. A frame, in accordance with the invention, is comprised of pulses spaced to minimize pulse collisions and configured to tolerate occasional collisions without impairing the monitor's ability to separately identify each transmitting sender. Each sender is configured to repeatedly transmit a unique identification frame characterized by a pulse pattern comprised of active intervals spaced by inactive (or “quiet”) intervals. The inactive intervals have variable length durations which are preferably pseudorandomly selected so that each sender defines a unique sequence of inactive interval durations.

Abstract: Described are communication systems that convey differential and common-mode signals over the same differential channel. Noise-tolerant communication schemes use low-amplitude common-mode signals that are easily rejected by differential receivers, thus allowing for very high differential data rates. Some embodiments employ the common-mode signals to transmit backchannel signals for adjusting the characteristics of the differential transmitter. Backchannel control signals are effectively conveyed even if the forward channel transmitter is so maladjusted that the received differential data is unrecognizable. Systems in accordance with the above-described embodiments obtain these advantages without additional pins or communications channels, and are compatible with both AC-coupled and DC-coupled communications channels. Data coding schemes and corresponding data recovery circuits eliminate the need for complex, high-speed CDR circuits.

Abstract: A system and method that scrambles the phase characteristic of a carrier signal are described. The scrambling of the phase characteristic of each carrier signal includes associating a value with each carrier signal and computing a phase shift for each carrier signal based on the value associated with that carrier signal. The value is determined independently of any input bit value carried by that carrier signal. The phase shift computed for each carrier signal is combined with the phase characteristic of that carrier signal so as to substantially scramble the phase characteristic of the carrier signals. Bits of an input signal are modulated onto the carrier signals having the substantially scrambled phase characteristic to produce a transmission signal with a reduced PAR.

Abstract: A communication system is provided including a transceiver and an application controller to transmit and receive signals through the transceiver. An isolator which insulates and separates the transceiver and application controller includes primary and secondary side circuits insulated from each other on a substrate and a capacitive insulating means to transfer signals between the primary and second sides while insulating and separating the primary side circuit from the secondary side circuit.

Abstract: The invention relates to a method for determining the correlation phase between a signal received at a receiver and a replica sequence. A matched filter multiplies samples (21) of the received signal with samples (22) of the replica and sums the resulting products to obtain a correlation value for a specific correlation phase. The samples of the received signal and the replica are shifted relative to each other for each correlation phase that is to be checked. In order to reduce the computational load, it is proposed that results obtained in the correlation calculations for one correlation phase are used by the matched filter also for calculations for a subsequent correlation phase. The invention relates equally to a corresponding receiver, to an electronic device comprising such a receiver, to a device cooperating with such a receiver and to a corresponding system.

Abstract: A method, apparatus, and system for measuring a distance between two points that includes measuring a distance intermediate a first data point and a second data point in each of two dimensions and adding the absolute values of those measured distances.

Abstract: Signalling between transmitting means and receiving means wherein signals from the transmitting means are subjected by the receiving means to deliberate reflections and resulting signals are transmitted back as meaningful at the transmitting means, different deliberate reflections having effects on said resulting signals that have different meanings at said transmitting means. Two-way signalling involves first signalling in one direction by sending signals with certainty of deliberate reflection thus resulting signals for return related to the signals sent according to the nature of the deliberate reflection and second signalling in the other direction by varying the nature of the deliberate reflection.

Abstract: A nonlinear distortion compensating device splits its operation into two processes. One is a compensation & amplification process for providing a receipt signal with a distortion compensating calculation and amplification before outputting the signal with phase and amplitude compensated. The other is an environmentally adapting process for modulating the signal demodulated from the input signal. Then in this process, a distortion estimating updater estimates a distortion amount using the modulated signal and a feed back signal of parts of the output supplied from the distortion compensating calculator, and updates a distortion compensating coefficient stored in the distortion compensating calculator.

Abstract: In one aspect, the present invention is directed to a technique of, and system for enhancing the performance of high-speed digital communications through a communications channel, for example a backplane. In this aspect of the present invention, a transmitter includes equalization circuitry to compensate for bandwidth limitations and reflections in high-speed digital communication systems. In one embodiment, the equalization circuitry is designed, programmed and/or configured to introduce intersymbol interference in order to improve the signal integrity in high-speed communications and enhance the operation and performance of such systems. In this regard, the equalization circuitry includes temporally overlapping leading and/or trailing taps (relative to the data (symbol) signal) to reduce, minimize, mitigate or effectively eliminate pre-cursor and/or post-cursor intersymbol interference due to, for example, bandwidth limitations and reflections in high-speed digital communication systems.

Abstract: Digital communication signals that encode information in the phase may be susceptible to phase error from many sources. The invention corrects for carrier and sampling phase errors, as well as additive phase noise. A digital phase locked loop simultaneously tracks the carrier phase error and the sampling phase error, and corrects the signal in the frequency domain. The invention may use the sampling phase error to advance or delay the sampling window used to convert the signal from the time domain to the frequency domain.

Abstract: A system and method for channel estimation in a wireless local area network. A corresponding channel estimation method includes the steps of: receiving a preamble message and despreading the preamble message into several symbol signals, each symbol signal containing several discrete signals; determining for each symbol signal a peak sign assignment; establishing several data windows for the symbol signals at the starting points of the discrete signals; multiplying the discrete value of each discrete signal of each data window by the corresponding peak sign assignment and accumulating the product in the first data frame; repeating the above steps for the next discrete signal and accumulating them in the second data frame, . . . , the Nth data frame; computing the accumulated value in the data frames and obtaining the data frame with the maximum value; estimating a channel signal from the previously determined data frame.

Abstract: The present invention is directed to a system and method which statistically determines when regularly occurring interference events of a predictable duration will occur, for example radar pulses and dynamically adjusts an automatic gain control (AGC) for RF data transmissions accordingly. The repetition rate and width of radar pulses are regular. By averaging and watching for correlations, the present AGC identifies the pulse rate and pulse widths and over a fairly short period of time predicts when the next pulse is coming. When the next pulse occurs, the AGC is adjusted to react accordingly. The AGC can raise or lower gain levels for the duration of the pulse; or ignore the pulse, if it is of a very short duration, so that the AGC level will coast through the event.

Abstract: A method and system for modulating and detecting high datarate symbol communications provides superior performance in channels having a fixed spectral efficiency. A quadrature amplitude modulation (QAM) constellation and an optimized mapping are employed to encode/detect a communications signal and error correction is provided using high speed forward error correction techniques. A log likelihood detection scheme and/or a novel phase detector may be employed to further enhance performance.

Abstract: A radio receiver handles a transmitted Walsh sequence having a code length of “m” as a two-dimensional array of “a” rows and “b” columns, and performs a fast Hadamard transform process having a code length of “a” in the row direction. The absolute values of the results are added in the column direction, and a Walsh number having the maximum receiving power is selected to determine a Walsh sequence having a code length of “a.” Then, only the identified column is extracted, and a fast Hadamard transform process having a code length of “b” is applied in the column direction.

Abstract: A transceiver includes a switching unit configurable for isolating an input of a receiver from an output of a transmitter during a local calibration mode. A known signal present at the output at a first power level during the calibration mode will also be present at the input at a second power level lower than the first power level and will be converted by the quadrature demodulator. A compensation factor is estimated for compensating the receiver section for imbalances in the in-phase and quadrature phase signals resulting from conversion of the known signal. Remote calibration is implemented using a method for remotely compensating for I-Q imbalance wherein a data packet having a known signal is transmitted to a receiver for conversion by a quadrature demodulator and compensation factors are estimated for compensating for imbalances in the in-phase and quadrature phase signals resulting from conversion of the known signal.

Abstract: A substantially passive implementation of a clock recovery circuit may be employed to reduce or eliminate the amount of jitter added to the recovered clock by the recovery circuitry. NRZ data may be received in differential form (i.e., a separate NRZ signal and an inverted NRZ signal are received). The inverted NRZ data may be delayed by one-half of a unit interval with respect to the NRZ data by a delay element. The NRZ data and the delayed NRZ data may be combined by a broadband combiner (e.g., a resistive adder). The combined signal may be split into two signals. The two split signals may be rectified by suitable components. One of the limited split signals may be subtracted from the other limited split signal to generate an output signal. The generated output signal then possesses a spectral component at a clock frequency of the NRZ data.