Abstract: An RF transmitter (10) includes an RF amplifier (28) that generates an amplified RF signal (36) including a linear RF signal (92) and a spurious baseband signal (94). The spurious baseband signal (94) interacts with bias feed networks (56, 66) to cause the RF amplifier (28) to generate an unwanted RF distortion at or near the allocated RF bandwidth. A baseband compensation signal (98) is generated and equalized in an adaptive equalizer (102) then fed to the RF amplifier (28). A feedback signal (46) is obtained from the RF amplifier (28) and used to drive the adaptive equalizer (102). A feedback loop causes the adaptive equalizer to adjust a baseband signal (24, 32) supplied to the RF amplifier (28) so that the RF distortion is minimized.

Abstract: A transmitter (50) includes a low power nonlinear predistorter (58) that inserts predistortion configured to compensate for a memoryless nonlinearity (146) corresponding to gain droop and another memoryless nonlinearity (148) corresponding to a video signal. When efforts are taken to reduce memory effects, such as configuring a network of components (138) that couple to an HPA (114) to avoid resonance frequencies substantially throughout a video bandwidth (140), high performance linearization at low power results without extending linearization beyond that provided by the memoryless nonlinear predistorter (58). A look-up table (282) has address inputs responsive to a magnitude parameter (152) of a communication signal (54). A pre-distorted communication signal (60) is responsive to the output of the look-up table, a derivative signal (204), and possibly one or more variable bias parameters (85). The look-up table (282) is updated in response to an LMS control loop.

Abstract: A transmitter (50) includes a low power nonlinear predistorter (58) that inserts predistortion configured to compensate for a memoryless nonlinearity (146) corresponding to gain droop and another memoryless nonlinearity (148) corresponding to a video signal. When efforts are taken to reduce memory effects, such as configuring a network of components (138) that couple to an HPA (114) to avoid resonance frequencies within a video bandwidth (140), high performance linearization at low power results without extending linearization beyond that provided by the memoryless nonlinear predistorter (58). A unadaptable look-up table (370) has address inputs responsive to a magnitude parameter (152) of a communication signal (54), a magnitude derivative parameter (204) of the communication signal (54), and a parameter (346, 366) related either directly or indirectly to battery voltage.

Abstract: A transmitter (50) includes a low power memoryless nonlinear predistorter (58) that inserts predistortion configured to address a nonlinearity (146) corresponding to gain droop and another nonlinearity (148) corresponding to deviations from an average bias condition. When efforts are taken to reduce memory effects, such as configuring a network of components (138) that couple to an HPA (114) to avoid resonance frequencies within a video bandwidth (140), high performance linearization at low power results without extending linearization beyond that provided by the memoryless nonlinear predistorter (58). Each nonlinearity is addressed by applying gain to a communication signal (54). The amount of gain applied is determined by a look-up table (170) for one nonlinearity (146) and by a look-up table (198) in combination with a differentiator (202) for the other nonlinearity (148). The look-up tables (170, 198) are updated in accordance with modified LMS control loops.

Abstract: A transmitter (50) includes a nonlinear predistorter (58) having two instances of an inverting transform (106, 106?) that may be implemented in a look-up table (122) and that implements a transform which is the inverse of an average terms component (96) of a nonlinear transform model (94) for an amplifier (70). The look-up table (122) may be updated using a continuous process control loop that avoids Cartesian to polar coordinate conversions. One of the two instances of the inverting transform (106) is cascaded with a non-inversing transform (108) within a residual cancellation section (110) of the predistorter (58). The non-inversing transform (108) implements a transform which is an estimate of a deviation terms component (98) of the nonlinear transform model (94). The residual cancellation section (110) produces a weak signal that replaces an unwanted residual term in an amplified communication signal (76) with a much weaker residual term.

Abstract: A transmitting unit (12) clips a communication signal (14) to form a threshold-responsive signal (36, 36?) which includes in-band distortion (40) and out-of-band distortion (38). A portion of the out-of-band distortion (38) is notched within rejection bands (48, 50) adjacent to the communication signal's bandwidth (24). But remaining portions of the out-of-band distortion (38) and portions of the in-band distortion (40) are included with the communication signal (14). The remaining portion of the out-of-band distortion (38) causes the communication signal (14) to be in violation of a spectral mask (30). The mask-violating communication signal 14 with out-of-band distortion (38) and in-band distortion (40) is amplified by an RF power amplifier (22). After amplification, a bandpass filter (92) exhibiting fast rolloff regions (110) attenuates the amplified out-of-band distortion (38) causing compliance with the spectral mask (30).

Abstract: A transmitter (50) includes a low power memoryless nonlinear predistorter (58) that inserts predistortion configured to address a nonlinearity (146) corresponding to gain droop and another nonlinearity (148) corresponding to deviations from an average bias condition. When efforts are taken to reduce memory effects, such as configuring a network of components (138) that couple to an HPA (114) to avoid resonance frequencies within a video bandwidth (140), high performance linearization at low power results without extending linearization beyond that provided by the memoryless nonlinear predistorter (58). Each nonlinearity is addressed by applying gain to a communication signal (54). The amount of gain applied is determined by a look-up table (170) for one nonlinearity (146) and by a look-up table (198) in combination with a differentiator (202) for the other nonlinearity (148). The look-up tables (170, 198) are updated in accordance with modified LMS control loops.

Abstract: A transmitter (50) includes a low power nonlinear predistorter (58) that inserts predistortion configured to compensate for a memoryless nonlinearity (146) corresponding to gain droop and another memoryless nonlinearity (148) corresponding to a video signal. When efforts are taken to reduce memory effects, such as configuring a network of components (138) that couple to an HPA (114) to avoid resonance frequencies within a video bandwidth (140), high performance linearization at low power results without extending linearization beyond that provided by the memoryless nonlinear predistorter (58). A look-up table (282) has address inputs responsive to a magnitude parameter (152) of a communication signal (54), a magnitude derivative parameter (204) of the communication signal (54), and possibly one or more variable bias parameters (85). The look-up table (282) produces a gain-correcting signal (284) that adjusts the gain applied to the communication signal (54) prior to amplification.

Abstract: A transmitter (50) includes a nonlinear predistorter (58) having two instances of an inverting transform (106, 106?) that may be implemented in a look-up table (122) and that implements a transform which is the inverse of an average terms component (96) of a nonlinear transform model (94) for an amplifier (70). The look-up table (122) may be updated using a continuous process control loop that avoids Cartesian to polar coordinate conversions. One of the two instances of the inverting transform (106) is cascaded with a non-inversing transform (108) within a residual cancellation section (110) of the predistorter (58). The non-inversing transform (108) implements a transform which is an estimate of a deviation terms component (98) of the nonlinear transform model (94). The residual cancellation section (110) produces a weak signal that replaces an unwanted residual term in an amplified communication signal (76) with a much weaker residual term.

Abstract: A transmitter (50) includes a nonlinear predistorter (58) having two instances of an inverting transform (106, 106?) that may be implemented in a look-up table (122) and that implements a transform which is the inverse of an average terms component (96) of a nonlinear transform model (94) for an amplifier (70). The look-up table (122) may be updated using a continuous process control loop that avoids Cartesian to polar coordinate conversions. One of the two instances of the inverting transform (106) is cascaded with a non-inversing transform (108) within a residual cancellation section (110) of the predistorter (58). The non-inversing transform (108) implements a transform which is an estimate of a deviation terms component (98) of the nonlinear transform model (94). The residual cancellation section (110) produces a weak signal that replaces an unwanted residual term in an amplified communication signal (76) with a much weaker residual term.

Abstract: An RF transmitter (60) generates non-DC bias signals (104, 106) configured to improved power-added efficiency (PAE) in the operation of an RF amplifier (94). The RF amplifier (94) generates an amplified RF signal (126) which, due to the addition of the bias signals (104, 106), includes bias-signal-induced RF distortion (48, 50). The bias signals (104, 106) drive a bias-induced distortion cancellation circuit (152) that adjusts the bias signals to compensate for the influence of impedances experienced by the bias signals (104, 106) before being applied to the RF amplifier (94). After mixing with a baseband communication signal (64), adjusted bias signals (186, 188) are combined into a composite baseband signal (76), upconverted to RF in an upconversion section 84, and applied to the RF amplifier (94) where they cancel at least a portion of the bias-signal-induced RF distortion (48, 50).

Abstract: A direct sequence spread spectrum (DSSS) transmitter (12) is configured to form “N” multiple excess-bandwidth channels (44) in an allocated bandwidth (54), where N is an integer. Each excess-bandwidth channel (44) includes a lower rolloff band (40), a minimum-bandwidth channel (38), and an upper rolloff band (42). The N excess-bandwidth channels (44) are placed in the allocated bandwidth (54) so that two of the rolloff bands (40, 42) reside within allocated bandwidth 54 and outside all of minimum-bandwidth channels 38 and so that N?2 of the rolloff bands (40, 42) predominately reside within adjacent minimum-bandwidth channels (38). The excess-bandwidth channels (44) substantially conform to EV-DO standards, and four of the excess-bandwidth channels (44) are supported for each 5 MHz of allocated bandwidth (54).

Abstract: A transmitting unit (12) clips a communication signal (14) to form a threshold-responsive signal (36, 36?) which includes in-band distortion (40) and out-of-band distortion (38). A portion of the out-of-band distortion (38) is notched within rejection bands (48, 50) adjacent to the communication signal's bandwidth (24). But remaining portions of the out-of-band distortion (38) and portions of the in-band distortion (40) are included with the communication signal (14). The remaining portion of the out-of-band distortion (38) causes the communication signal (14) to be in violation of a spectral mask (30). The mask-violating communication signal 14 with out-of-band distortion (38) and in-band distortion (40) is amplified by an RF power amplifier (22). After amplification, a bandpass filter (92) exhibiting fast rolloff regions (110) attenuates the amplified out-of-band distortion (38) causing compliance with the spectral mask (30).

Abstract: A communication system (10) includes a transmitting unit (12) with a peak to average power (PAPR) reduction section (30). The PAPR reduction section (30) modifies the PAPR reduction it effects in a communication signal (14) in accordance with two different error vector magnitude (EVM) constraints for each channel type (102), where a channel type (102) is a distinct combination of a modulation order and a coding rate. The EVM constraint followed for each subcarrier (25) in an OFDM or OFDMA application is selected in response to whether the subcarrier (25) conveys voice or non-voice data. The PAPR reduction section (30) may include a scaling filter (72). The scaling filter (72) is efficiently defined through the use of a predetermined sinc function (94) and a first stage scale factor (67) that is calculated in response to a weighted average of excursion signal subcarrier gains (150), where the weighting follows the distribution of channel types (102) through the subcarriers (25).

Abstract: An RF transmitter (10) includes an RF amplifier (22) that experiences gain-droop distortion as a result of self-heating. A heat compensator (20) is included to insert a gain boost of an amount which is the inverse of the gain droop experienced by the RF amplifier (22). The amount of gain boost is determined by generating a heat signal (88) from low-pass filtering (86) the squared magnitude (82) of a communication signal (14). The heat signal (88) is scaled by a weighting signal (68) estimated by monitoring the amplified RF signal (42) at the output of the RF amplifier (22). A nonlinear relationship section (96) then transforms the scaled signal into a gain-boost signal (94) that corresponds to the inverse of gain droop in the RF amplifier (22).

Abstract: A signal processing system according to various aspects of the present invention includes an excursion signal generator, a scaling system and a filter system. The excursion signal generator identifies a peak portion of a signal that exceeds a threshold and generates a corresponding excursion signal. The scaling system applies a real scale factor to contiguous sets of excursion samples in order to optimize peak-reduction performance. The filter system filters the excursion signal to remove unwanted frequency components from the excursion signal. The filtered excursion signal may then be subtracted from a delayed version of the original signal to reduce the peak. The signal processing system may also control power consumption by adjusting the threshold. The signal processing system may additionally adjust the scale of the excursion signal and/or individual channel signals, such as to meet constraints on channel noise and output spectrum, or to optimize peak reduction.

Abstract: A cellular communication system includes a plurality of base stations (20), each of which assigns all frequency division multiplex, forward link carriers (32) to either a high-power set (42) of carriers (32) or a low-power set (44) of carriers (32) to improve system capacity and reduce boundary interference in a K=1 frequency reuse plan. The low-power set (44) has fewer members than the high-power set (42). The carriers (32) are simultaneously transmitted, preferably from an omnidirectional antenna (26). Access terminals (76) are configured to select carriers (32) from low-power set (44) for the receipt of data from base stations (20) when such carriers (32) from low-power set (44) provide an acceptable data rate, even though other carriers (32) may have higher SINR.

Abstract: A signal processing system according to various aspects of the present invention includes an excursion signal generator, a scaling system and a filter system. The excursion signal generator identifies a peak portion of a signal that exceeds a threshold and generates a corresponding excursion signal. The scaling system applies a real scale factor to contiguous sets of excursion samples in order to optimize peak-reduction performance. The filter system filters the excursion signal to remove unwanted frequency components from the excursion signal. The filtered excursion signal may then be subtracted from a delayed version of the original signal to reduce the peak. The signal processing system may also control power consumption by adjusting the threshold. The signal processing system may additionally adjust the scale of the excursion signal and/or individual channel signals, such as to meet constraints on channel noise and output spectrum, or to optimize peak reduction.

Abstract: A signal processing system according to various aspects of the present invention includes an excursion signal generator, a scaling system and a filter system. The excursion signal generator identifies a peak portion of a signal that exceeds a threshold and generates a corresponding excursion signal. The scaling system applies a real scale factor to contiguous sets of excursion samples in order to optimize peak-reduction performance. The filter system filters the excursion signal to remove unwanted frequency components from the excursion signal. The filtered excursion signal may then be subtracted from a delayed version of the original signal to reduce the peak. The signal processing system may also control power consumption by adjusting the threshold. The signal processing system may additionally adjust the scale of the excursion signal and/or individual channel signals, such as to meet constraints on channel noise and output spectrum, or to optimize peak reduction.

Abstract: A signal processing system according to various aspects of the present invention includes an excursion signal generator, a scaling system and a filter system. The excursion signal generator identifies a peak portion of a signal that exceeds a threshold and generates a corresponding excursion signal. The scaling system applies a real scale factor to contiguous sets of excursion samples in order to optimize peak-reduction performance. The filter system filters the excursion signal to remove unwanted frequency components from the excursion signal. The filtered excursion signal may then be subtracted from a delayed version of the original signal to reduce the peak. The signal processing system may also control power consumption by adjusting the threshold. The signal processing system may additionally adjust the scale of the excursion signal and/or individual channel signals, such as to meet constraints on channel noise and output spectrum, or to optimize peak reduction.