Abstract: An RF transmitter includes a Cartesian to polar conversion section, a PLL, a DAC module, a mixing module, and a PA module. The Cartesian to polar conversion section converts a Cartesian based symbol stream into a polar based symbol stream. The PLL generates an oscillation when the RF transmitter is in a Cartesian mode or a phase modulated oscillation based on phase modulation information of the polar based symbol stream when the RF transmitter is in a polar mode. The mixing module mixes an analog Cartesian based signal with a local oscillation to produce a Cartesian based up converted signal when the RF transmitter is in the Cartesian mode and mixes an analog amplitude signal with a phase modulated local oscillation to produce a polar based up converted signal when the RF transmitter is in the polar mode.

Abstract: Methods and apparatus are provided to enable a transceiver (200) or transmitter including a single PA line-up (210) to transmit signals having frequencies in two or more different frequency bands, and/or having two or more different modulation types, and/or having two or more different RF power levels. The single PA line-up includes at least one variable matching circuit (216) and a variable harmonic filter (240) to tune match and tune filter communication signals prior to transmission. The variable matching circuit and the variable harmonic filter each include at least one variable capacitive element (2160 and 2400) that switches ON/OFF depending on whether a low frequency signal or a high frequency signal is being transmitted. Each variable capacitive element includes separate direct current and radio frequency terminals to enable the single PA line-up to change signal modulation and/or RF power levels in addition to frequencies.

Abstract: Described is a communication system including mobile communication devices. In the described system, the mobile devices may be wrist-worn watches such as are in common use today, except that the watches are specially configured to receive data in a “broadcast” mode and transmit and/or receive data in a “localcast” mode. The localcast mode includes the ability to transmit and receive data in a peer-to-peer fashion, allowing mobile devices to communicate directly with each other. The ability to combine two of these communication modes in a small, integrated and hence inexpensive and low-power package provides many advantages over existing personal communication device solutions.

Abstract: A multiple-mode modulator is configured similarly to a direct conversion quadrature modulator with an infusion of an amplitude modulation signal path from a large signal polar modulator to improve the power amplifier efficiency. The multiple-mode modulator also includes a radio frequency signal path. The multiple-mode modulator is configured to receive a baseband signal, convert the baseband signal to a radio frequency (RF) signal, and to process the RF signal according to either a polar mode or a quadrature mode, depending on a time-varying input voltage of the RF signal. When the power amplifier operates in the linear region, the RF signal is processed according to the quadrature mode. When the power amplifier operates in the compressed region, the RF signal is processed according to the polar mode. The multiple-mode modulator can be configured according to a small signal polar architecture or a large signal polar architecture, having either an open-loop or closed-loop configuration.

Abstract: Various approaches to localized jamming of navigation signals are provided. In one embodiment, a navigation signal comprises at least a portion of a low earth orbit (LEO) signal provided by a LEO satellite. A noise source is filtered to provide a plurality of filtered noise signals in a plurality of frequency bands. The navigation signal is spread over a plurality of channels of the LEO signal. The channels are distributed over the frequency bands and a plurality of time slots. A pseudo random noise (PRN) sequence is generated. The filtered noise signals are modulated using the PRN sequence to provide a plurality of modulated noise signals. The modulated noise signals are broadcast over an area of operations to provide a plurality of jamming bursts corresponding to the navigation signal. The jamming bursts are configured to substantially mask the navigation signal in the area of operations.

Abstract: A radio frequency transmitter includes a baseband transmit processing module, a mixing module, a power amplifier, a transmit power sense module, and a transmit power control module. The baseband transmit processing module is operably coupled to encode outbound data into outbound baseband signals in accordance with one of a plurality of encoding protocols. The mixing module is operably coupled to convert the outbound baseband signals into outbound radio frequency signals. The power amplifier is operably coupled to amplify the outbound RF signals prior to transmission to produce amplified outbound RF signals. The transmit power sense module is operably coupled to sense the amplified outbound RF signals to provide a transmit signal strength indication (TSSI). The transmit power control module is operably coupled to adjust gain of the baseband transmit processing module, the mixing module, and/or the power amplifier based on the TSSI and the particular encoding protocol used to produce the baseband signals.

Abstract: A radio communication system for enabling control of a modulation scheme following variation in the propagation channel and control of a coding rate in a small amount of delay and arithmetic operation. In order to attain the object explained above, a transmitter station and a receiver station use in common the information of the maximum number of bits used for communication of each symbol. The transmitter station generates codeword by previously encoding the communication signal with the code having sufficient error correcting capability, assigns, to each symbol, the codeword to result in the maximum number of bits per symbol, and modulates and transmits the bits using the modulation scheme in which the number of bits per symbol is equal to or less than the maximum number of bits per symbol.

Abstract: The back-off of an AGC diversion section can be appropriately controlled.

Abstract: A transmitter operates to increase a diversity order of a multi-carrier frequency division multiplex (MC-FDM) system. The transmitter has at least two transmit antennas and circuitry to provide at least two of the MC system frequency sub-carriers to different ones of the at least two transmit antennas.

Abstract: A signal generation section 11 generates an amplitude signal M and an angle-modulated signal S?. An adaptive compensation filter 12 performs waveform shaping on the amplitude signal M in accordance with a magnitude of the amplitude signal M. An amplitude amplification section 14 outputs a signal proportional to a magnitude of the signal subjected to waveform shaping in the adaptive compensation filter 12. An amplitude modulation section 15 amplitude-modulates the angle-modulated signal by the signal outputted from the amplitude amplification section 14 and outputs the resulting signal as a modulated signal. Characteristics of the adaptive compensation filter 12 are inverse characteristics of transfer characteristics from an input of the amplitude amplification section 14 to an output of the amplitude modulation section 15.

Abstract: Disclosed is an OFDM (orthogonal frequency division multiplexing) wireless communication system operable on a frequency selective channel, and a channel compensation method. An IDFT (inverse discrete Fourier transform) unit of a transmitter includes first through third N-point IDFT units, and performs IDFT on a binary information signal twice. A DFT (discrete Fourier transform) unit of a receiver includes first through third N-point DFT units, a channel predictor and interpolator, and a channel compensator, and performs DFT on the signal received from the transmitter twice.

Abstract: To modulate the frequency of a signal to be transmitted, the biasing voltage applied to a terminal of a transistor is dynamically modulated. To achieve this, the pulse width or a pulse amplitude of a control signal is modulated. Alternatively, a multi-bit control signal may be used to perform the modulation. The frequency of the transmitted signal is optionally modulated by varying the temperature of a oscillator. To vary this temperature, the current flowing through one or more resistive elements positioned in proximity of the oscillator is varied in response to the pulse width or amplitude of a second control signal. The temperature may also be changed by varying a multi-bit control signal. As the level of this current flow varies, the amount of heat emitted by the resistors vary, thereby changing the temperature of the oscillator which has a non-zero temperature coefficient.

Abstract: Systems and methods for optimizing transmission of a plurality of data streams on a multiple-input multiple-output channel are described. The systems and methods for optimizing reduce the multiple-input multiple-output channel for each transmission scheme to an equivalent single-input single-output channel for the transmission scheme and transmit the plurality of data streams based on the single-input single-output channel for the transmission scheme. Systems and methods for optimizing the transfer of data for any number of transmit and receive antennas are described.

Abstract: A method and system transmits an input stream of data symbols in a multiple-input/multiple-output wireless communications system that includes M subgroups of transmitting antennas. A stream of data symbols is provided to a combined switch and demultiplexer. The combined switch and demultiplexer selects a subset L of the M subgroups of antennas as active, where L<M. The demultiplexer then splits the data stream into L substreams, which are fed to the L subgroups of antennas. Before transmission, each of the L substreams is adaptively modulated and coded to a maximum data rate while achieving a predetermined performance on an associated channel used to transmit the substream. Space-time transmit diversity encoding is applied to each coded substream to generate multiple output streams, one output stream for each antenna of each of the L subgroups. The selection by the switch is based on channel conditions fed back by a receiver of the output streams.

Abstract: A method signals in an ultra-wide bandwidth network. A data symbol is generated. A set of reference pulses is transmitted for the data symbol. Each reference pulse is of a different type. One data pulse is also transmitted for each reference pulse. A type of each data pulse is identical to the type of the corresponding reference pulse.

Abstract: A wireless communications system can include a charged particle generator configured to generate plural energized particles and a charge transformer configured to receive the plural energized particles that include charged particles from the charged particle generator and to output energized particles that include particles having substantially zero charge. The charged particle generator can be configured to direct the plural energized particles through the charge transformer to propagate through free space until received by a broadband signal receiver that can demodulate a data signal to complete the data communication.

Abstract: In an information transmission method, a radio communications system, a base station and a mobile station, a TBS size, a modulation scheme and the number of codes in a multicode are converted into identification data having a relatively smaller data size before being transmitted to a destination of communication. The TBS size is identified by using, in combination, an identification code identifying a channelization code set, an identification code identifying a modulation scheme, and an identification code obtained by converting a combination of the number of codes in a multicode and a modulation pattern identification (TFRC) into a corresponding code. Accordingly, the data size for TBS size identification is reduced.

Abstract: Apparatuses, systems and methods for transmitting and receiving modulated impulse radio signals. An impulse radio receiver includes a time base, a precision timing generator, a template generator, a delay, first and second correlators, a data detector and a time base adjustor. The time base produces a periodic timing signal that is used by the precision timing generator to produce a timing trigger signal. The template generator uses the timing trigger signal to produce a template signal. A delay receives the template signal and outputs a delayed template signal. When an impulse radio signal is received, the first correlator correlates the received impulse radio signal with the template signal to produce a first correlator output signal, and the second correlator correlates the received impulse radio signal with the delayed template signal to produce a second correlator output signal. The data detector produces a data signal based on at least the first correlator output signal.

Abstract: A modulator 23 corrects an amplitude signal Rd by adding thereto an offset value ? and generates, based on the corrected amplitude signal Rd, an amplitude signal Ra for amplitude-modulating a radio-frequency signal. The modulator 23 includes: an offset voltage measurement section 109 operable to measure an offset voltage V2cal of the amplitude signal Ra; a correction value calculation section 110 operable to obtain a difference value ?V2cal between the offset voltage V2cal measured by the offset voltage measurement section 109 and an initial value of the offset voltage V2cal and operable to calculate, based on the difference value ?V2cal, a correction value VODAC for correcting the offset voltage V2cal; and an addition section 106 operable to add the correction value VODAC calculated by the correction value calculation section 110 to a signal processed until the amplitude signal Ra is generated from the amplitude signal Rd.

Abstract: A transmitter employing variable gain amplifiers and operating with both constant and nonconstant envelope modulation systems is contrived to suppress variation in the transmitting power when constant envelope modulation is performed. The transmitter comprises a PM loop, an AM loop, and a variable gain amplifier which is shared by the PM loop and the AM loop and combines phase information that the PM loop outputs and envelope information that the AM loop outputs by gain control. The variable gain amplifier comprises a variable gain amplifier body having a supply voltage terminal and a bias current detection terminal for extracting a bias current corresponding to a gain, wherein the gain changes with a change in the potential of the supply voltage terminal, and a bias control block connected to the supply voltage terminal and the bias current detection terminal.

Abstract: Generally, implementations provide a circuit framework that uses phase and amplitude modulation with several voltage-controlled-oscillators (VCOs) and corresponding variable gain amplifiers (VGAs) to generate and amplitude and phase modulated signals that are summed to an output signal for a transmitter circuit. The implementations can involve decomposing an input signal into a number of decomposed signals using a signal decomposer component, in which each of decomposed signals includes phase and amplitude information. The signal decomposer component can interact with each of the VCOs and corresponding VGAs to conduct the phase and amplitude modulation for the amplitude and phase modulated signals. The multiple standard transmitter circuit can be used for one or more communication standards, such as Global System for Mobile Communications (GSM), a Wideband Code Division Multiple Access (WCDMA), or High-Speed Uplink Packet Access (HSUPA), among others.

Abstract: A single chip integrated circuit wireless data processor demodulates N separate data signals from M separate antennas simultaneously. The multi-antenna processor can be coupled to a baseband processor on the IC, so that it responds to changing channel conditions between two access points, and selectively kicks in if there is noise, interference, frequency fading, a need for an enhanced data rate, a need for an increased operating range, etc. to improve a performance of the baseband processor.

Abstract: Methods, systems, and devices are described for providing predictive adaptive communications. Embodiments include a network access unit, in communication with multiple data terminals, and adapted to determine geospatial and other network data (e.g., current capability and position information relating to a designated one of the data terminals, map data, etc.), and to generate a link condition prediction as a function of the network data. The network access unit may then adaptively encode source data (e.g., using adaptive coding and modulation of hierarchically pre-coded data) to preempt impacts of changing link conditions on communications with the designated data terminal as a function of the link condition prediction.

Abstract: The present invention involves a method for transmitting data having primary and secondary data. A first transmit signal is transmitted from a first communication satellite wherein the first transmit signal is produced when the transmitter modulates the primary and secondary data on a first carrier wave associated with the first communication satellite, with secondary data having a first polarity. A second transmit signal is transmitted from a second communication satellite wherein said second transmit signal is produced when the transmitter modulates the primary and secondary data on a second carrier wave associated with the second communication satellite with secondary data having a second polarity opposite the first polarity.

Abstract: There is provided with an amplifier comprising: first and second power amplifiers; a first path configured to output first and second input signals to the first and second power amplifiers; a second path configured to divide a first input signal, output one of divided signals to the first power amplifier and output the other divided signal to the second power amplifier; a first path changeover unit configured to change over the first and second paths; a third path configured to output first and second power amplified signals from the first and second power amplifiers; a fourth path configured to combines a first power amplified signal through an impedance conversion unit from the first power amplifier and a second power amplified signal from the second power amplifier at a combining point and output a combined signal; and a second path changeover unit configured to changeover the third and fourth paths.

Abstract: An object of the invention is to provide a polar modulation circuit capable of reducing the capacity of data stored in memory and suppressing an increase in the circuit scale related to distortion compensation while assuring the compensation accuracy. The polar modulation circuit according to the invention stores output signal characteristic relative to the control voltage at the steady state after input of the control voltage for a predetermined input amplitude of an input high frequency signal as the basis of distortion compensation of an amplifier separately into an offset storage section 101a which stores data used to add a predetermined DC offset voltage and a coefficient storage section 102 which stores data used for multiplication by a predetermined constant, thus reducing the circuit scale related to distortion compensation while assuring the compensation accuracy.

Abstract: In an envelope comparison embodiment, a delay calibrator produces a delay signal based on a comparison of a feedback signal and an envelope component of the transmitted signal. A down-converter produces the feedback signal from an outgoing modulated RF signal based on at least one local oscillation. Envelope detectors in the delay calibrator and the envelope signal path are operably coupled to a summing node that produces a delay error signal based on a temporal difference between the two envelopes. One embodiment includes phase detectors to detect and adjust the zero crossings of the feedback signal and the envelope signal path. As the delay mismatch between the envelope signal path and the phase signal path increases, the power spectrum increases in adjacent communication channels. A mask margin measurement technique measures the power level in an adjacent channel and adjusts the envelope path delay accordingly.

Abstract: A transmitting apparatus of the present invention includes an orthogonal modulator for generating a modulated signal by using an input signal; a polar-modulation-mode transmission circuit which includes a first power amplifier whose input terminal receives a phase component of the modulated signal generated by the orthogonal modulator and whose power supply terminal receives an amplitude component of the modulated signal generated by the orthogonal modulator, and which polar-modulates the modulated signal; an orthogonal-modulation-mode transmission circuit which includes a second power amplifier whose input terminal receives the modulated signal generated by the orthogonal modulator and whose power supply terminal receives a constant voltage, and which transmits the modulated signal; and a switch for connecting an output of the orthogonal modulator with an input of the polar-modulation-mode transmission circuit at the time of a high output, and for connecting the output of the orthogonal modulator and an inpu

Abstract: The invention involves selection of modulation scheme for a mobile unit (100) having access to a link quality enhancing algorithm (130) operable only on data modulated using a subset of the available modulation schemes. The mobile unit (100) performs signal quality measurements on a communications link (410), over which data modulated with a first modulation scheme is communicated. A link quality measure is then determined for this first modulation. A quality enhancement due to operation of the algorithm (130) is also determined. This quality measure and the quality enhancement are used for generating decision information, which is reported to the network (200). There the information is used for estimating link quality measure(s) of currently non-employed modulation(s) for the mobile unit (100). The selection of a modulation scheme for the communications link is then performed based on the decision information and the estimated quality measure(s).

Abstract: An amplitude component of a modulating signal is detected, band-divided by first and second frequency selecting circuits, and an amplitude component of a high-frequency band is down-converted by a first frequency conversion circuit. An amplitude component selected by the first frequency selecting circuit and an amplitude component selected by the first frequency conversion circuit are amplified by first and second operational amplifiers, and a signal amplified by the second operational amplifier is up-converted by a second frequency conversion circuit to be restored to the initial frequency band. Output amplitudes of the first operational amplifier and a second frequency converter are added up by an adder to be direct-current converted. The amplitudes after the direct-current conversion are band-divided by third and fourth frequency selecting circuits, respectively, feedback amounts thereof are adjusted, and then fed back to the first and second operational amplifiers.

Abstract: A dual band direct conversion architecture for both the receive (RX) and transmit (TX) path of a communications transceiver that minimizes the transceiver area by sharing common circuits used in both RX and TX paths is disclosed. The transceiver also allows the use of extensive digital calibration in order to achieve performance adequate to support high bit rate modulation schemes.

Abstract: A low noise RF driver circuit including at least two series-coupled driver stages which receive a frequency modulated signal and an amplitude modulated signal that is applied to the supply voltage input of the driver stages, and provide a combined output signal. The RF driver circuit can be implemented in CMOS technology and integrated with other components of an RF communication subsystem, such as an RF transceiver circuit and power amplifier. Each driver stage includes a complementary pair of transistors with source degeneration resistors for linearity and gain control.

Abstract: The aim of the invention is to suppress interference caused by a mismatch of the power amplifier of a polar-loop transmitter. To achieve this, the crest factor of the output signal from the power amplifier is measured during operation to detect the state of the mismatch and to identify the modification of the transfer characteristic curve of the power amplifier. The crest factor that have been determined are compared with a target value and if the crest factor deviates from the target value, the bandwidth or the amplification of the amplitude closed loop is adapted accordingly., The transmitter can thus regulate the non-linear distortion that occur as a result of the mismatch. Said measures improve the linear behavior or degree of efficiency of the power amplifier.

Abstract: Apparatus and method for generating first, second and third carrier frequencies of 3432 MHz, 3960 MHz and 4488 MHz respectively, for use in a wireless transmission system deploy only first and second PLLs which are configured to generate 6336 MHz and 2640 MHz signals respectively with only in-phase components. Frequency dividers are employed for frequency-dividing the 6336 MHz signal severally by 2, 4, and 12 to obtain frequency-divided intermediate outputs with both in-phase and quadrature components. The intermediate output components and other intermediate signal components are selectively combined in a mixer (e.g., a single side-band mixer), for deriving the first, second and third carrier frequencies of 3432 MHz, 3960 MHz and 4488 MHz with both in-phase and quadrature components. The invention has application in UWB, WPAN, WLAN, or other wireless systems and has the simplicity and advantages of using only two PLLs instead of the prior art arrangements of three PLLs.

Abstract: A transmitter adopting a polar loop system including a phase control loop for controlling the phase of a carrier signal outputted from a transmitting oscillator and an amplitude control loop for controlling the amplitude of a transmitting output signal outputted from a power amplification circuit, and designed to be capable of performing transmission using a GMSK modulation mode and transmission using an 8-PSK modulation mode. In the transmitter, the phase control loop is shared as a phase control loop for use in the GMSK modulation mode and a phase control loop for use in the 8-PSK modulation mode. A component similar to any one of components constituting a loop filter is provided in parallel therewith so that the component can be connected or disconnected in accordance with the modulation mode, for example, by use of a switching element.

Abstract: A radio system having an improved phase noise characteristic and a thereby improved communication quality, a radio transmitter, and a radio receiver. In the radio system, a radio transmitter (101) transmits a multiplexed signal so multiplexed that a pilot signal transmitted at the center frequency.

Abstract: An amplitude modulator is provided, which has a first supply connection for supplying a supply potential and a second supply connection for supplying a ground potential. An amplifier stage with a push-pull output stage has a signal input for supplying a signal, and has a single-pole output for emitting a single-ended signal. In order to supply the push-pull output stage, the amplifier stage is connected in a supply path between the first and the second supply connection. A first controllable voltage source and a second controllable voltage source are also provided, whose control inputs are connected to a connection for control purposes by means of a differential modulation signal, and are connected between the amplifier stage and the first supply connection, or the amplifier stage and the second supply connection. Amplitude modulation is thus achieved by modulation of the supply voltage or of the supply current to the push-pull output stage.

Abstract: A polar modulator has a low AM-AM and AM-PM distortion comprises a phase locked loop. The phase locked loop is designed for outputting a high-frequency signal with a frequency derived from a phase modulation signal at an actuating input of the phase locked loop. A filter device, for suppressing a DC signal component, is coupled to an output of the phase locked loop. Furthermore, provision is made of a controllable voltage source with a control input suitable for feeding in an amplitude modulation signal. A push-pull amplifier is connected by an input to the filter device. It comprises two feedback amplifier transistors connected in series, which are connected to a voltage output of the controllable voltage source for supply purposes. Control terminals of the amplifier transistors are connected to the input and, via a load, to an output of the push-pull amplifier.

Abstract: An apparatus and method for amplifying a radio frequency signal including, generating a plurality of shaped pulses utilizing a piecewise linearizer circuit, applying the plurality of shaped pulses to a first input of a radio frequency amplifier circuit, and injecting a radio frequency carrier into a second input of the radio frequency amplifier circuit. The apparatus comprises a piecewise linearizer (PWL) circuit coupled to the input of a Radio Frequency Digital to Analog Converter (RFDAC) operating as a signal amplifier.

Abstract: In a transmitter of polar-loop architecture having a phase control loop and an amplitude control loop, as loop filters for controlling a loop band of the amplitude control loop, a first filter with lag-lead characteristics (secondary or more filter including a capacitor and a resistor) and a second filter of a perfect integrator type (filter including only a capacitor) are employed, and current-output type circuits are connected to respective front stages of the first and second filters.

Abstract: A polar transmitter, operable in linear mode or switched mode, uses a conversion module to convert baseband signals into amplitude data and phase data. The phase data is used to phase modulate a carrier frequency in a radio frequency conversion module. The module comprises a plurality of parallel unit cells, each being a mixer cell type converter having a differential data switch section connected in series to a differential local oscillator-switch pair. The differential local oscillator-switch is connected in series to a current source. Each unit cell is adapted to receive a signal through an input end. In switched mode, the phase-modulated carrier frequency is amplitude modulated by the amplitude data through the supply voltage to a power amplifier. In linear mode, amplitude data is conveyed to the input end of the unit cells for modulating the phase-modulated carrier frequency in the conversion module.

Abstract: A transmitter and method is provided for digitally upconverting a baseband digital signal to a modulated intermediate frequency (IF) digital signal and sigma-delta modulating the IF digital signal. The baseband digital signal is split into N phases, as can be accomplished using a polyphase interpolation technique (polyphase filter), and modulated. The modulated N phases are not recombined and each phase is further modulated, as can be accomplished using a digital-to-digital sigma-delta modulator that generates digital output signals at the same rate. A high speed digital multiplexer multiplexes the digital output signals into a single bit stream at a higher rate for subsequent power amplification and RF transmission.

Abstract: A system for dynamically adapting a communication channel to channel impairments includes a spectrum monitor configured to determine a channel impairment characteristic related to a channel impairment present in the channel. The system includes a system manager configured to determine a quality metric indicative of channel performance for the channel, and adjust one or more operating parameters in a set of channel operating parameters when the quality metric is not within a target range, whereby the communication channel operates in accordance with the adjusted parameters.

Abstract: A frequency modulation method is provided in which the frequency of a carrier signal is modulated on the basis of the frequency of a modulation signal, and in which the modulation signal is integrated. The carrier signal is integrated, and a differential signal is formed from the integrated modulation signal and the integrated carrier signal. The differential signal is phase-modulated in order to obtain the frequency-modulated carrier signal as the output signal.

Abstract: Downlink diversity in a CDMA system is provided by employing Walsh codes in conjunction with M transmit antennas at a common base station serving K mobiles, where M may or may not be to equal to K. The present invention provides methods and apparatus for improving downlink diversity in a CDMA system. Each transmit antenna transmits a signal representing the result of the modulation of Walsh codes by data signals for each of the K mobiles, assuming there is data pertaining to a particular mobile. The assignment of Walsh codes is accomplished in accordance with a transmission matrix T. The transmission matrix maps the user data symbols onto the Walsh codes for each antenna and is preferably designed such that its columns are representative of the transmit antennas and orthogonal.

Abstract: The present invention, generally speaking, provides for high-efficiency power control of a high-efficiency (e.g., hard-limiting or switch-mode) power amplifier in such a manner as to achieve a desired modulation. In one embodiment, the spread between a maximum frequency of the desired modulation and the operating frequency of a switch-mode DC-DC converter is reduced by following the switch-mode converter with an active linear regulator. The linear regulator is designed so as to control the operating voltage of the power amplifier with sufficient bandwidth to faithfully reproduce the desired amplitude modulation wave-form. The linear regulator is further designed to reject variations on its input voltage even while the output voltage is changed in response to an applied control signal. This rejection will occur even though the variations on the input voltage are of commensurate or even lower frequency than that of the controlled output variation.

Abstract: A radio channel simulator configured to read radio channel data describing a radio channel and user data including at least one user signal, and to simulate the radio channel using a FIR filter comprising one or more FIR blocks for filtering the user data read based on radio channel data in connection with the simulation. The radio channel simulator is configured to transfer at least one FIR block at a delay level depicting a radio channel delay during simulation.

Abstract: A preamble generation method and apparatus are provided for improving transmit diversity by changing a preamble structure in a broadband wireless communication system using multiple antennas based on a multiple input multiple output (MIMO) scheme. First pilot tones associated with different antennas are selected. The first pilot tones are multiplied by different first Walsh codes. Second pilot tones associated with the same antenna are sequentially selected along a frequency axis. The second pilot tones are multiplied by a second Walsh code. Preambles are generated by assigning, to at least two symbol durations, output signals multiplied by the first and second Walsh codes. Consecutive pilot tones during each of the at least two symbol durations are spaced by one pilot tone, and code streams of the first and second Walsh codes are alternately multiplied by the pilot tones. The preamble structure has orthogonality between the antennas using frequency, time and code domains.

Abstract: In one embodiment, a PLL circuit is provided with a plurality of pull-in operation modes for pulling a voltage across a filter capacitor (C1, C2) in a lock-up voltage, and with a register (CRG) for designating one of the plurality of pull-in operation modes. The pull-in operation is performed in accordance with a setting value in the register.

Abstract: Provided is a frequency modulation circuit for outputting a frequency-modulated signal with a high precision. A VCO 13 includes a first variable capacitor 132 having a predetermined capacitance change rate, and a second variable capacitor 133 having a greater capacitance change rate than that of the first variable capacitor 132. When the frequency modulation circuit is applied in a narrowband modulation method, a switch 15 switches a connection path of an open loop such that an input terminal and the first variable capacitor 132 are connected. On the other hand, when the frequency modulation circuit is applied in a wideband modulation method, the switch 15 switches the connection path of the open loop such that the input terminal and the second variable capacitor 133 are connected.