摘要:
A radio communications device such as a receiver, transmitter or transceiver provides direct conversion of quadrature signals between a radio frequency signal and a plurality of resolved channels. The device provides block processing of multiple RF carriers in a wireless communication system using a direct conversion transmitter/receiver and baseband signal processing.
摘要:
A method for wireless communication that dynamically adjusts RF amplifier operating bias for the subscriber unit's transmitter in response to a power control signal. The invention provides high-efficiency RF power amplification for applications where the available power source is limited. The invention uses a power control signal resident in wireless communication system architectures with a detector and voltage to current converter to arrive at a dynamic amplifier operating bias.
摘要:
A digital baseband (DBB) radio frequency (RF) receiver used for receiving and processing a wireless communication signal. The DBB receiver includes a demodulator, first and second analog low pass filters (LPFs), first and second digital gain control circuits, and a digital time domain compensation module which removes group delay variation distortion, introduced by the first and second analog LPFs, from real and imaginary signal components of the communication signal.
摘要:
A modem is configured for demodulating a communication signal associated with a unique code-division multiple access (CDMA) code. The modem includes an adaptive matched filter and a vector correlator. The vector correlator generates filter coefficients for the adaptive matched filter based on signal distortion determined by the vector correlator. The vector correlator has a processing capacity of at least eleven chips whereby the vector correlator compensates for a known phase distortion and for multipath distortion ascertainable within its processing capacity. The adaptive matched filter processes communication signals with the unique CDMA code using coefficients generated by the vector correlator.
摘要:
The present invention is a transmitter circuit in which envelope tracking of a power amplifier output is used to derive its power supply modulation. The circuit includes a power amplifier for amplifying an RF signal, a voltage power source and a switching amplifier for producing a modulated output responsive to the envelope of the amplified RF signal. The transmitter circuit further comprises a peak detector that eliminates the transmit carrier signal in the power supply modulation signal. A fraction of the PA output is utilized by the switching amplifier and the peak detector to produce a signal that follows the baseband signal envelope and is used to modulate the bias of the power amplifier.
摘要:
A communication system emulator digitally emulates a plurality of signal impairments created by the transmitter and receiver components and communication medium in a typical communication system, for use in evaluating and refining modem design. A variety of linear and non-linear distortion characteristics are impressed on baseband signals between modulators and demodulators to evaluate and refine modem performance without requiring transmission frequency components or communication channel. The emulator comprises transmit modules, receive modules and communication media modules, and can accept or output analog or digital signals. Each module is configurable to allow modeling of simplex or duplex communication, or a common base station with multiple users transmitting or receiving, all configurations with or without communication media impairment emulation. Each module can be configured to add a plurality of linear and non-linear impairments to a baseband signal.
摘要:
A method and apparatus that reduces the amount of constellation rotation due to power amplifier (PA) insertion phase variation during activation (i.e., turn on) of a transmitter. This is accomplished by applying an instantaneous phase rotation during the transmitter turn on at digital baseband to counteract and minimize unwanted phase variations.
摘要:
A wireless transmit/receive unit (WTRU) uses an oscillator providing accuracy for synchronized communications parameters in an active mode, and operates at reduced power during a discontinuous reception (DRX) mode. A real time clock (RTC) is used as the frequency standard during the reduced power operation, and a frequency adjustment is effected while the RTC is used as the frequency standard. By effecting the frequency adjustment, the RTC is able to be used as the frequency standard for substantial time periods, thereby reducing power consumption of the WTRU during the DRX mode.
摘要:
A CDMA base station includes an antenna system having multiple antennas and delay units for receiving a transmitted signal and outputting a combined signal having a known distortion imparted by the antenna system. The combined signal is in turn processed by a modem, which compensates for the known distortion in a manner which provides improved signal gain. The improved signal gain permits a reduction in transmit power and, accordingly, increased capacity of the base station. Where the antenna system is to be remotely located from related signal processing equipment, separate units for the RF receiver/transmitter and the other signal processing equipment are provided so that the RF receiver/transmitter may also be remotely located along with the antenna system.
摘要:
In order to compensate for performance degradation caused by inferior low-cost analog radio component tolerances of an analog radio, a wireless communication transmitter employs a control process to implement numerous digital signal processing (DSP) techniques to compensate for deficiencies of such analog components so that modern specifications may be relaxed. By monitoring a plurality of parameters associated with the analog radio, such as temperature, bias current or the like, enhanced phase and amplitude compensation, as well as many other radio frequency (RF) parameters may be implemented.