Motorola Corporation

Cyntrust Communications, Inc.

James Wesley McCoy

Raja Sekhar Bachu

Leo George Dehner

A modulator, and demodulator, apparatus and method for use in a multiple sub-channel communication system is taught. A commutator is employed for fractionally sampling, or distributing, signals from, or to, a multiple channel polyphase filter. The filter is coupled with a discrete Fourier transform, or its inverse, such that the relationship between the base-band sampling rate of a plurality of sub-channel signals, the frequency spacing of the sub-channel signals, and the sampling rate of a composite signal can be related by any rational number, thereby freeing designers to optimize system design respecting channel spacing, bandwidth, and signaling rates. The advantages of the present invention are realized by adjusting the interpolation and decimation rates of the filter, and by adjusting the resolution and decimation rates of the transform.

Multiple sub-channel modulation and demodulation with arbitrarily defined channel spacing and sampling rates

A method for multi-user detection in a CDMA communication system using a finite-impulse-response matrix filter includes a first step of inputting a received sequence of multi-user data from a channel of the communication system. A next step includes truncating a block convolution matrix representing an infinite-impulse-response matrix filter so as to provide a finite-impulse-response matrix filter equalizer by using a system matrix with smaller number of columns than the frame length. A next step includes operating on the received sequence of multi-user data with the finite-impulse-response filter so as to provide an estimate of user data for any particular user.

Multi-user detection using a finite-impulse-response matrix filter

A processor (,) receives an input signal including symbols for transmission, and determines an output signal for a symbol period from a predetermined range of symbols of the input signal in combination with a modulating phasor vector and a matrix of filter coefficients. The processor compares samples of the output signal with a predetermined amplitude limit; and, in response to a sample of the output signal exceeding the predetermined amplitude limit, adjusts the symbols of the predetermined range of symbols that are not pilot symbols by an adjustment factor, thereby creating a new input signal. If a sample of the output signal exceeds the predetermined amplitude limit, the processor computes a new output signal from the new input signal in combination with the modulating phasor vector and the matrix of filter coefficients; and generates a power-controlled modulated radio signal from the new output signal.

Method and apparatus for power control in a transmitter

A modulator (102) generates a frequency-multiplexed composite signal (502) including a plurality of symbols. A processing system (108) of the modulator defines (802) a signal template (600) specifying symbol-type adjustment factors for corresponding symbol types, and then locates (804) in the composite signal a portion of the signal whose amplitude exceeds a predetermined threshold by an amplitude excess. The processing system records (806) the amplitude excess, the phase angle, and a time of the portion; and determines (808) an input symbol corresponding to the time, the input symbol being of a symbol type. The processing system adjusts (810) the input symbol in accordance with one of the plurality of symbol-type adjustment factors corresponding to the symbol type, and further in accordance with the amplitude excess and the phase angle, thereby bringing the amplitude below the predetermined threshold.

Method and apparatus for peak limiting in a modulator

A multichannel polyphase filter (304, 602) includes a processing system (204, 506) for accepting and processing M input channels of data, each sampled at an input sampling rate, wherein M is a positive integer greater than unity. The processing system is programmed to provide a commutator (308, 606) for the multichannel polyphase filter, wherein the position of the commutator is decoupled from the phase of a filter impulse response selected for the position, thereby allowing the multichannel polyphase filter to be operated at a sampling rate that is a non-integer multiple of the input sampling rate. The processing system is further programmed to operate the multichannel polyphase filter at the non-integer multiple of the input sampling rate to obtain a non-integer sampling rate change.

Apparatus for performing a non-integer sampling rate change in a

A transmitter (1) with improved average power comprises a mixer (34) for receiving an input signal (21) and providing a mixed signal (23) to an average power controller (14) comprising a fast automatic gain controller (26) for receiving the mixed signal and providing a conditioned signal to a hard limiter (28) for foldback clipping the conditioned signal to provide an output signal (15). The average power controller further comprises an error control signal generator (24, 30, 36) for generating an error control signal (27) calculated by subtracting (36) an average power estimation (30) of the output signal from a given nominal average power value (24). Finally, the average power controller also comprises a feedback loop (29) for feeding back the error control signal to the mixer for controlling the gain of the input signal.

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Trophy Club, TX, United States of America

James Wesley McCoy