Abstract: An apparatus for generating a preamble sequence in an orthogonal frequency division multiplexing (OFDM) communication system using A subcarriers in a frequency domain. A preamble sequence generator generates a length?M+N+k preamble sequence, where M+N+k is less than A, by combining a length?N Golay complementary sequence with a length?M Golay complementary sequence. An inverse fast Fourier transform (IFFT) processor assigns elements constituting the preamble sequence to the M+N+k subcarriers among the A subcarriers on a one-to-one mapping basis, assigns null data to remaining subcarriers excluding the M+N+k subcarriers from the A subcarriers, and then IFFT-transforms the assigned result into time-domain data.

Abstract: A decision-driven control loop wherein a first reconstructed signal is compared to an unreconstructed data symbol signal to initially drive the control loop. A second reconstructed signal that is based on a longer memory path than the first reconstructed signal is evaluated against the first reconstructed signal. The decision-driven control loop is ultimately controlled based on the results of the evaluation between the first and second reconstructed signals. The inventive decision-driven control loop, which may be implemented in software, may form part of a read channel in a storage device.

Abstract: In order to perform appropriate reception quality control on each mobile station in a multimedia broadcast/multicast service, a layered coding section 101 encodes input data by dividing the input data into two layers and obtains a first layer code string and a second layer code string. The first layer code string is input to a CRC code addition section 102 and a CRC code for an error inspection is added thereto at every predetermined block. On the other hand, the second layer code string is input to a CRC code addition section 103 and a CRC code for an error inspection is added thereto at every predetermined block. The first layer code string and the second layer code string with the CRC codes added are input to a layered modulation section 104 and the layered modulation section 104 modulates a plurality of code strings coded by being divided into a plurality of layers in such away that error rates differ hierarchically among the plurality of code strings and a radio section 105 sends the modulated symbol.

Abstract: A fast Walsh transform (FWT) demodulator and a method are provided. The FWT demodulator includes a FWT correlator for receiving and transforming a first information based on a FWT method to output third information; power approximation devices (PAD) for receiving and calculating one of the third information to output an approximating power value respectively. Wherein, the approximating power values are divided into subgroups. A first unit of comparators selects subgroup-max-values from each subgroup. A plurality of power calculation devices (PCD) are for receiving and calculating one of the subgroup-max-value to output a precise power value respectively. A second unit of comparators is for selecting max power value from each precise power value to output a second information. By applying “PAD” to replace “PCD” into “pre-selection” subgroups with “max-and-zero” property, the invention can reduce the implementation cost without performance degradation.

Abstract: A modem system for receiving and transmitting signals having a frequency domain equalizer (FEQ) block being responsive to a frequency channel response for processing the same to generate one or more initial FEQ coefficients (FEQ1), the modem system is responsive to an input signal for processing the same to generate frequency channel response, the input signal being generated from a transmitted signal, FEQ block using FEQ1 to generate an equalized Signal, modem system demodulating equalized Signal to generate a demodulated Signal symbol, in accordance with an embodiment of the present invention.

Abstract: A method is presented for estimating a phase error for first (rI) and second (rQ) orthogonal signal components spread respectively by different first cI and second cQ spreading codes. A cross-despread value IdQ and/or QdI is determined by despreading one signal component with the spreading codes associated with the other signal component (rI with cQ or rQ with cI). In parallel, the same signal component is also despread with its associated spreading code to determine an estimated data symbol for that component. An interference of Q into I or I into Q is calculated and multiplied by the estimated data symbol, and subtracted from the cross-despread value to achieve an estimate of phase error. Preferably, both cross-despread values are obtained, normalized to a common data rate, scaled to maximize signal to noise ratio, and combined into one phase error estimate. A phase error detector includes despreaders, multipliers, and adders to determine the cross-despread value and subtract the interference from it.

Abstract: An apparatus and method for slicing an RF signal and compensating for the slice level of an RF signal reproduced from a disk, which minimizes a block error rate by optimizing the slice level of the RF signal according to variations in symmetry of the RF signal when slicing the RF signal. A comparator converts the RF signal reproduced from the disk into a digital signal by comparing the RF signal with a slice level, a low-pass filter low-pass filters the digital signal and provides the result to the comparator as the slice level, and a slice level compensator compensates for the slice level provided to the comparator by the low-pass filter according to variations in symmetry of the RF signal.

Abstract: There is provided a device and method for transmitting packet data in a mobile communication system. A sub-code generator generates a plurality of sub-codes with the same or different code rates for the input of a PLP (Physical Layer Packet) information bit stream. A controller determines a minimum data rate by which the number of the modulation symbols of a sub-code generated by a predetermined modulation method is equal to or greater than the number of transmittable modulation symbols for each time period. A symbol pruner prunes part of the modulation symbols of the sub-code to make the number of the modulation symbols of the sub-code equal to the number of transmittable modulation symbols for the time period, if the number of the modulation symbols of the sub-code is greater than the number of transmittable modulation symbols for the time period.

Abstract: Apparatus and method are disclosed for selecting a transmit antenna diversity scheme according to a variation speed of a fading channel in a mobile communication system. A user equipment (UE) estimates a channel response of a pilot channel by receiving a pilot channel signal from a Node B; estimates a variation speed of a fading channel by using the estimated channel response and determining a transmit antenna diversity scheme suitable to the variation speed of the fading channel; and transmits feedback information including the determined transmit antenna diversity scheme to the Node B, so that the Node B can determine a transmit antenna diversity scheme for a channel signal to be transmitted to the UE based on the transmit antenna diversity scheme information included in the feedback information. In this way, the Node B adaptively applies a transmit antenna diversity according to a channel condition.

Abstract: A frequency estimation method of multiband (MB)-orthogonal frequency division multiplexing (OFDM) ultra wide band (UWB) system using an Alt-PHY time frequency (TF) hopping strategy based on IEEE 802. 15. 3a. includes the steps of: a) selecting a predetermined number of frequencies among a plurality of center frequencies based on a predetermined number of OFDM symbols and estimating relative frequency offsets for selected frequencies; b) obtaining an average relative frequency offset by averaging the estimated relative frequency offsets when two or more frequencies are selected at the step a); and c) obtaining real frequency offsets for each of the center frequencies by transforming the obtained average relative frequency offset to the real frequency offsets and compensating a frequency offset caused by a transmitting/receiving local oscillators based on the obtained real frequency offsets.

Abstract: A system for implementing Incremental Redundancy (IR) operations in a wireless receiver includes a baseband processor, an equalizer, a system processor, and an IR processing module. The baseband processor receives an analog signal corresponding to a data block and samples the analog signal to produce samples. The equalizer receives the samples from the baseband processor, equalizes the samples, and produces soft decision bits corresponding to the data block. The equalizer may be implemented as a distinct processing component or may be performed by the baseband processor or system processor. The system processor receives at least the soft decision bits and initiates IR operations. The IR processing module receives the soft decision bits of the data block and performs IR operations on the data block in an attempt to correctly decode a corresponding data block.

Abstract: A method transmits data to be transmitted using a subscriber modem of a subscriber access network with adjusted transmission power. The method includes selecting at least one transmission frequency band and subdividing the selected transmission frequency band into several sub-frequency bands. The method also includes determining the maximum transmission power corresponding to each sub-frequency band and transmitting data, using an adjusted transmission power, to a switching modem in the subscriber access network via a corresponding subscriber line. In single-carrier operating mode, the data is transmitted in all sub-frequency bands using a specific, uniform transmission power of the maximum transmission powers that have been determined. In multiple-carrier operating mode, the data is transmitted in the sub-frequency bands using the respective maximum transmission power which has been determined.

Abstract: Noise and signal-to-noise ratio (SNR) estimation are relatively straightforward tasks. However, when SNR is small, systematic errors in measurement may result in over-estimation of SNR, which also occurs during runtime monitoring of SNR. Here, sufficient numbers of bits have been preassigned to each channel using QAM modulation scheme. Therefore, SNR relative to QAM lattice size depends on the noise margin and the desired (bit error rate) BER. If a relatively small margin is desired, similar measurement errors may result in over-estimation of SNR. Another problem that arises is that the variance of the noise estimator is relatively high. Therefore, SNR estimates may vary by several dB, and there is only 50% confidence in the usual estimators that the actual SNR value will not be worse than that estimated. Thus, a computationally efficient method for SNR estimation that also allows for specification of a confidence level in the estimates is provided.

Abstract: A digital direct access arrangement (DAA) circuitry may be used to terminate the telephone connections at the user's end that provides a communication path for signals to and from the phone lines. Briefly described, the DAA provides a programmable means for the DC termination for a variety of international phone standards. The invention may also be utilized with means for transmitting and receiving a signal across a capacitive isolation barrier. More particularly, a DC holding circuit is provided in which a programmable DC current limiting mode is available. In the current limiting mode, power may be dissipated in devices external to a DAA integrated circuit. Moreover, much of the power may be dissipated in external passive devices, such as resistors.

Abstract: The present invention discloses a clock generator circuit for generating an output clock signal. The clock generator circuit includes: a random frequency code generator for generating a frequency code randomly, wherein the random frequency code generator is clocked by a first clock signal; an accumulator electrically connected to the random frequency code generator, for generating a selection code by accumulating the frequency code, wherein the accumulator is clocked by the first clock signal; a first multiplexer electrically connected to the accumulator, for selecting one of a plurality of reference clock signals as the first clock signal according to the selection code; and a toggle circuit electrically connected to the first multiplexer, being clocked by the first clock signal for generating the output clock signal.

Abstract: A channel tracking module, configured for generating updated equalization coefficients for a frequency equalizer, is configured for determining a digital-based error value between equalized signals output by the frequency equalizer relative to predicted signals, for each subcarrier frequency of an OFDM symbol. The channel tracking module determines an accumulated error based on accumulating the digital-based error values for all the subcarrier frequencies of the OFDM symbol, for a prescribed successive number of OFDM symbols. The channel tracking module also determines a step size based on the accumulated error and relative to a prescribed step function configured for optimizing equalizer adjustments within stability limits. The channel tracking updates the equalization coefficients for each subscarrier frequency based on the accumulated error and the step size.

Abstract: A channel estimation apparatus in a digital communication system includes: a correlation unit for obtaining a correlation function of a first received signal by correlating a received synchronizing signal and a reference synchronizing signal, and obtaining a correlation function of the received synchronizing signal by a correlation between the synchronizing signals, a first estimating unit for estimating a first multi-path by applying a first threshold value to the correlation function of the first received signal, a correlation noise removing unit for obtaining a correlation function of a second received signal by removing correlation noise included in the correlation function of the first received signal, by a first multi-path, and a second estimating unit for estimating a second multi-path by applying a second threshold value to a correlation function of the second received signal in which the correlation noise has been removed.

Abstract: A digital wireless communication apparatus includes a first modulator that modulates a pilot symbol according to a first modulation scheme, and a second modulator that modulates specific symbols according to a second modulation scheme, the second modulation scheme being different than the first modulation scheme. A third modulator modulates symbols other than the pilot symbol and the specific symbols according to a third modulation scheme, the third modulation scheme being different than the first and second modulation schemes. A timing controller controls timing such that the specific symbols are inserted immediately before and after the pilot symbol. The signal points of the specific symbols are allocated on an imaginary line that connects the origin point and a signal point of the pilot symbol on a signal space diagram.

Abstract: A spread spectrum communication system and a method can provide resistance against selective fading and can prevent lowering of circuit use ratio with lowering reception bit error ratio. The spread spectrum communication system has a control unit for controlling a transmission band width and a transmission power of a counterpart equipment depending upon a communication quality.

Abstract: Data communication for wired and or for wireless communication and broadcasting systems for broadband, ultra wideband and ultra Narrowband (UWN) reconfigurable, interoperable communication and broadcasting system architectures. Combinations and hybrids of ultra wideband (UWB), ultra narrowband (UNB) and efficient broadband wireless, baseband, intermediate frequency (IF) and radio frequency (RF) implementations for Bit Rate Agile (BRA) reconfigurable and interoperable systems. Processing the data signals, of clock signals, and/or carrier cycles waveforms leads to shaped radio-frequency (RF) cycles, waveforms and wavelets.