Abstract: Systems and methods which introduce a variable shift with respect to pilot symbols in providing a data subcarrier channel estimation are shown. Use of pilot symbol shifts may be useful, for example, when path delay is long and/or when non-consecutive, non-uniformly distributed pilot subcarriers are used. The foregoing shift may be introduced in the time or frequency domains according to embodiments of the invention. For example, a shift of a particular number of samples may be introduced with respect to the symbols of the pilot subcarriers in the measured pilot subcarrier channel response for use in data subcarrier channel estimation.

Abstract: Provided herein are systems and methods for achieving long integration of an input signal by compensating the frequency and phase of each sample of the input signal. In an embodiment, a Numerical Controlled Oscillator (NCO) of the receiver is modified to include a variable control input that allows the output frequency of the NCO to be adjusted based on a rate of change of frequency. The rate of change of frequency may be estimated based on the relative velocity of a satellite to the receiver computed from satellite orbit parameters or ephemeris. The rate of change of frequency may also be estimated based on frequency measurements of previous samples. The modified NCO may be used as a carrier NCO or code NCO of the receiver to provide frequency and phase compensation of each sample of the input signal.

Abstract: A MIMO-OFDM transmission apparatus is provided which allows high accuracy estimation of frequency offset, high accuracy estimation of a transmission path fluctuation and high accuracy synchronization/signal detection. Pilot symbol mapping (1111) is provided for forming pilot carriers by assigning orthogonal sequences to corresponding subcarriers among OFDM signals which are transmitted at the same time from respective antennas in the time domain. Even when pilot symbols are multiplexed among a plurality of channels (antennas), this allows frequency offset/phase noise to be estimated with high accuracy.

Abstract: A digital broadcast system and method of processing digital data is disclosed, including a digital broadcast transmitter and digital broadcast receiver and methods thereof.

Abstract: A method of generating multi-channel local oscillation frequencies in an ultra wide band communication system includes generating: at least one reference frequency, a plurality of auxiliary frequencies by dividing and multiplying the at least one reference frequency, and a plurality of first local oscillation frequencies by mixing the reference frequency and at least some of the plurality of auxiliary frequencies with other auxiliary frequencies.

Abstract: A DTV transmitter includes a signal generator, an interleaver, a trellis encoder, and a modulator. The signal generator generates a first data group including first, second and third regions, the first and third regions including main data and RS parity data, the second region including enhanced data coded with a first coding rate, enhanced data coded with a second coding rate, a plurality of known data sequences, signaling information and RS parity data. The interleaver interleaves the first data group to generate a second data group including fourth, fifth and sixth regions, the fifth region including enhanced data, a plurality of known data sequences, signaling information, and RS parity data, the fourth region including main data, RS parity data, and enhanced data. The trellis encoder trellis-encodes the second data group. The modulator modulates a broadcast signal including the trellis encoded second data group.

Abstract: A method according to one embodiment for mitigating radio frequency interference by identifying system clocks, identifying active radio channels, measuring clock harmonics in or near the active radio channels, determining potential interference occurring if the clocks were moved to new fundamental frequencies, and shifting clock fundamental frequencies to reduce interference to the active radio channels based on existing interference and the potential interference of a plurality of new fundamental frequencies. Of course, many alternatives, variations, and modifications are possible without departing from this embodiment.

Abstract: A time reference point can be determined in a radio system by sending a synchronization sequence s(i), i=0, . . . N?1, from transmitter X, 40 to receiver Y, 48, and by detecting the peak value at the output of a matched-filter, 44, h(i)=s(N?1-i) on Y. In practical systems the accuracy of this peak detection is limited by interference and noise on the radio channel. To increase the peak detection accuracy, we propose to repeat the transmission of the same synchronization sequence K times. The interval L between repetitions is constant and the amplitude of the synchronization sequence in each repetition varies according to a given variation pattern a(jL), j=0, . . . , K?1. The receiver Y, 48 knows L and a(jL), j=0, . . . , K?1. After comparison to a threshold, the matched-filter 44 at the receiver 48 may deliver peaks resulted from repeatedly received synchronization sequences or peaks caused by interference and/or noise.

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 method includes receiving a reference signal and at least one delayed space-time encoded signal via at least two beams in which a time delay is associated with at least one of the at least two beams; determining channel state information based on the received reference signal and the received at least one delayed space-time encoded signal; and segmenting the channel state information into a plurality of channel state information segments.

Abstract: Provided is a sub-harmonic frequency mixer having a structure in which two terminals of transistors receiving a Radio Frequency (RF) signal and a Local Oscillation (LO) signal are coupled. The frequency mixer is composed of a single-level structure of transistors and thus can be driven at a lower supply voltage compared to a common frequency mixer. A direct-conversion receiver employing such a frequency mixer needs an RF signal and an LO signal sources of single-phase. Therefore, the direct-conversion receiver has an architecture that simplifies a whole RF transceiver circuit and thus can be advantageously applied in implementing SoC (System-on-Chip) for a low power, high integration, low price and subminiature wireless transceiver circuit.

Abstract: The present invention is directed to a system and method for channel estimation for a communication channel such as, for example, that found in a wireless communication network. One or more synchronization and channel estimate symbols can be combined to compute a refined channel estimate.

Abstract: Systems and methods are provided for precorrecting a constant envelope input signal. A phase precorrection component generates a precorrected input signal by applying a phase precorrection to the input signal. The applied phase correction alters an associated phase of the input signal without applying amplitude modulation to the signal. A linear distortion source applies amplitude distortion and phase distortion to the precorrected input signal. The applied phase correction mitigates the phase distortion applied by the linear distortion source.

Abstract: A method and an apparatus for transmitting information contained in a transmission signal via at least one channel includes a number of processing steps at the transmitter end. At least one pulse sequence with at least one pulse is produced as stipulated by the transmission signal. The pulse sequence is output to the at least one channel. The channel is monitored for the presence of an interference signal. If an interference signal is detected on the channel, the pulse sequence is repeated.

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: Embodiments of a correlator, a receiver, and a method for performing correlations are generally described herein. Other embodiments may be described and claimed. In some embodiments, input samples are phase-quantized into phase-quantized samples of substantially equal magnitude with approximately the original phase. The phase-quantized samples of substantially equal magnitude with approximately the original phase are correlated with a reference signal.

Abstract: Disclosed is a method, an apparatus and a mobile station embodiment to receive a CDMA signal from a radio channel. The method includes inputting a CDMA signal received through the radio channel to a searcher and processing the received signal in the searcher to obtain a multi-path profile of the radio channel. Processing includes at least partially removing an effect of at least one of a transmit and a receive filter on the multi-path profile. In one embodiment at least partially removing the effect of at least one of the transmit and receive filter on the multi-path profile involves passing the received CDMA signal through an N-tap Finite Impulse Response filter having a filter characteristic that approximates an inverted amplitude response of the at least one of the transmit and a receive filter, while in another embodiment software external to the searcher is used to process the searcher output data.

Abstract: One embodiment of the present invention includes a method for controlling a gain of a wideband signal. The method comprises adding a virtual channel to the wideband signal, the wideband signal comprising at least one channel. The method also comprises monitoring an output power associated with the wideband signal that includes the at least one channel and the virtual channel. The method further comprises setting a gain factor to achieve a predetermined output power of the wideband signal and amplifying the wideband signal based on the gain factor.

Abstract: A plurality of differential signal transmitters can transmit data signals differentially through a plurality of conductive signal lines. Ones of the signal lines can be shared between transmitters, and others of the signal lines need not be shared between transmitters.

Abstract: Digital communication signals that encode information in the phase may be susceptible to phase error from many sources. A device 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 device 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.