Abstract: A system and method for adjusting the power control target for a spread-spectrum communication system 110 is disclosed. A preferred embodiment comprises correcting a power control target 128 based upon the difference between a filtered series of actual error signals 124 and the expected number of errors 126 over a properly determined time window. By using a filtered series of actual error signals, the power control target update step-size is adaptive to the channel conditions, and the power-rise is reduced, thereby reducing power requirements and signal dropouts. The invention finds application, for example, in personal communication devices such as cellular telephones and may be implemented using a digital signal processor (DSP).

Abstract: A spreading code generating apparatus carries out M-sequence multiplication and zero value addition of generated orthogonal codes to obtain channel identification codes, and then carries out inverse Fourier transform of the channel identification codes to generate spreading codes and inverse spreading codes. A transmitting apparatus and a receiving apparatus store the spreading codes and the inverse spreading codes generated by the spreading code generating apparatus, respectively, and use a single code respectively selected from the stored codes to carry out spread spectrum communication. With the use of the spreading codes for spreading, the input signal is spread over a wide frequency band with uniform power on the frequency axis. Thus, transmission characteristics are improved, and multiplexing capacity is increased.

Abstract: The invention relates to an apparatus of transmitter and receiver for Multiple Input/Multiple Output MultiCarrier-Code Division Multiple Access (MIMO MC-CDMA) systems. At the transmitter, modified orthogonal transmit diversity (MOTD) encoders are used for increasing space and time transmission diversity. A P-way combiner is used to connect the MOTD encoders and P multi-carrier modulators. Each modulator is connected to a set of antennas. At the receiver, each multi-carrier demodulator has an amplitude/phase compensator to compensate distortion at every sub-carrier. Similarly, a combiner is used to connect the demodulators and the MOTD decoders. Upon the invention, the space, time, and frequency diversity can be explored.

Abstract: A digital receiving device includes a detecting means for detecting a specific code under a signal receiving state capable of successively receiving a desired signal, a setting means for setting a period for detecting the specific code as a non-communication state period, an adaptive filter having an adaptive mode and a non-adaptive mode, the adaptive mode by which a filter coefficient is sequentially updated so as to remove an ambient noise during the non-communication state period, and the non-adaptive mode by which the filter coefficient is stopped from being updated during a period except for the non-communication state period under the signal receiving state and a filter controlling means for controlling an operation for switching the adaptive mode and the non-adaptive mode of the adaptive filter.

Abstract: A signal reception method including method and apparatus for receiving a signal, down converting the received signal through multi-tone down conversion to form an intermediate signal, and decoding the intermediate signal to extract data. In an embodiment, the received signal may include multiple transmission bands of a multi-code (MC)-CDMA signal, each of which occupies a different spectrum. Each of the transmission bands also includes an information channel signal. When the received MC-CDMA signal is down converted through multi-tone down conversion, the intermediate signal is formed. The intermediate signal includes a common spectrum that includes an information channel from a plurality of transmission bands. When the intermediate signal is decoded, data from a plurality of information channel bands is extracted. The method and apparatus may be implemented in a multi-mode MC-CDMA/CDMA receiver.

Abstract: Communication is performed for a first communication device having a set of antenna elements. A quality-indication signal is received from a second communication device (e.g., a basestation). A complex weighting is calculated based on the quality-indication signal. A pre-transmission signal is modified based on the complex weighting to produce a set of modified-pre-transmission signals. Each modified pre-transmission signal from the set of modified-pre-transmission signals is uniquely associated with an antenna element from the set of antenna elements. The set of modified-pre-transmission signals is sent from the set of antenna elements to produce a transmitted signal. The complex weighting is associated with a total power of the transmitted power and at least one from a phase rotation and a power ratio associated with each antenna element from the set of antenna elements.

Abstract: A time signal receiver and decoder receives, detects and stores time information from time signals, e.g., WWV, WWVH, WWVB (USA), JJY (Japan), MSF (UK) and the like. The time information may be used for a self setting clock, and the clock may be used as a reference in time sensitive applications, devices and systems. The time signal receiver may use a high-Q state variable bandpass filter or an anti-notch filter circuit for selectivity at the time signal frequency of interest. The decoder is coupled to the time signal receiver, decodes the time information in the received time signal and may store the decoded time information.

Abstract: Disclosed is a chip-level or a symbol-level equalizer structure for a multiple transmit and receiver antenna architecture system that is suitable for use on the WCDMA downlink. The equalizer structure takes into account the difference in the natures of inter-antenna interference and multiple access interference and suppresses both inter-antenna interference and multiple access interference (MAI). Enhanced receiver performance is achieved with a reasonable implementation complexity. The use of the CDMA receiver architecture, in accordance with this invention, enables the realization of increased data rates for the end user. The CDMA receiver architecture can also be applied in conjunction with space-time transmit diversity (STTD) system architectures.

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 equalizer coefficients, the modem system is responsive to an input signal for processing the same to generate frequency channel response, the input signal being generated from transmission of a transmitted signal, FEQ block for using equalizer coefficients to generate an equalized channel response, modem system for using equalized channel response to generate one or more metric weights, in accordance with an embodiment of the present invention.

Abstract: An OFDM receiver has a DC offset estimator configured for determining a DC offset, in I and Q components of a received OFDM signal having been output by an analog front end, based on filtering prescribed subcarrier components from a preamble segment of the I and Q components. The OFDM receiver removes the determined DC offset from the I and Q components, resulting in respective corrected I and Q components having minimal DC offset.

Abstract: Methods and apparatus for use in making improved symbol decisions in a demodulator in the presence of distortion in the received signaling. In one implementation, a method includes the steps of: determining a centroid symbol location for a received symbol of a constellation, the centroid symbol location different than an ideal symbol location due to distortion of the received symbol; and adjusting a decision line bounding the received symbol based on the centroid symbol location. In preferred embodiments, the method is implemented in a satellite communication system, which the distortion is a nonlinear distortion and is caused by a high power amplifier at the transmitting terminal and in which bandwidth efficient modulation formats are used to transmit data at a high rate. In some embodiments, centroid symbol locations are used to improve soft decision decoding.

Abstract: Communication is performed for a first communication device having a set of antenna elements. A quality-indication signal is received from a second communication device. A complex weighting is calculated based on the quality-indication signal. A pre-transmission signal is modified based on the complex weighting to produce a set of modified-pre-transmission signals. Each modified pre-transmission signal from the set of modified-pre-transmission signals is uniquely associated with an antenna element from the set of antenna elements. The set of modified-pre-transmission signals is sent from the set of antenna elements to produce a transmitted signal.

Abstract: A phase locked loop (PLL) having an improved phase unlock detection function generates a clock pulse signal at a frequency from a synchronization signal of a cathode ray tube (CRT) monitor and includes a phase frequency detector (PFD), a charge pump, a loop filter, a Voltage Controlled Oscillator (VCO), a divider, a phase unlock detection circuit, a phase lock/unlock detection circuit, and an output circuit. The phase unlock detection circuit detects an initial generation of a phase unlock from the up or down signal, outputs a first detection signal, and outputs an internal control signal according to the up or down signal. The phase lock/unlock detection circuit outputs a second detection signal, in response to the internal control signal and the first detection signal. The output circuit performs a logic operation on the first detection signal and the second detection signal and outputs a third detection signal.

Abstract: A digital equalizer for interpreting a digital signal including convolutionally encoded symbols and synchronization symbols outside the convolutional code comprises a combined trellis encoder and DFE. The synchronization symbols are re-inserted into the input of the DFE in order to restore time domain continuity created by removal of the synchronization symbols.

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: Disclosed is radio equipment for transmission and reception of Frequency Division Duplex mode signals and transmission signal characteristic compensation utilizing small-scaled circuit construction. A receiver converts Radio Frequency band signals from an antenna sharer to an Intermediate Frequency (IF) via a mixer and into digital signals utilizing an Analog-to Digital Converter. Reception signals and image signals of transmission signals, both having an IF A are contained in the converted signals, are converted into reception signals having an IF B and image signals having an IF C, respectively, which both have positive and negative carrier frequencies symmetrical to a zero frequency direct current component and are represented as a complex number. A transmitter converts the IF C into a baseband of image signals, and compensates signal characteristics relative to complex baseband signals of quantized transmission signals at a characteristic compensator using converted signals as reference signals.

Abstract: A method is provided for receiving a multicarrier signal in a receiver implementing at least two distinct reception channels. After receiving the multicarrier signal during a first step, and in order to optimize subsequent processing (such as synchronization, confidence computing, . . . ), information representing the reception quality is associated to each corresponding reception channel during a second step. An embodiment of the disclosure relies on a new way of computing this information, called absolute confidence, which takes account on the one hand of the reception quality of the considered channel compared to the other channels (total confidence) and on the other hand of the reception quality of each source data (carrier) compared to the others, in the considered channel (relative confidence), to determine an absolute confidence for each data of each channel.

Abstract: Disclosed is an apparatus and method for reducing a peak-to-average power ratio (PAPR) due to multiple subcarriers in an OFDM (Orthogonal Frequency Division Multiplexing) mobile communication system. In the OFDM mobile communication system, a transmitter pre-emphasizes an output signal of an IFFT (Inverse Fast Fourier Transform) block, and a receiver de-emphasizes a received signal before FFT (Fast Fourier Transform), thereby efficiently reducing PAPR due to multiple subcarriers.

Abstract: The method comprises setting a threshold value, dividing the combined signal into blocks, comparing the values of each block with the set threshold value and if the threshold value is exceeded, decorrelating the block where the threshold value was exceeded and a pre-determined number of channelization codes, which have a pre-determined spreading factor. The decorrelation result is normalized to determine first weighting coefficients. The method also comprises comparing each combination of a first weighting coefficient and a related channelization code with the set objectives and determining second weighting coefficients for the downlink transmissions selected as a result of the comparison. The examined block is re-formed using combinations of the channelization codes and the weighting coefficients that were determined.

Abstract: An adaptation to Carrier Interferometry synthesis and analysis provides for complex coding and decoding in a sliding window transform. Coding and decoding functionality can be extended to spatial processing in systems employing multiple transceiver elements. Poly-amplitude codes permit successive interference cancellation in spatial and frequency-domain processing. Handoffs in cellular systems are facilitated by selecting spectral/base station combinations that optimize link performance.