In a signal cancellation method and device which can cancel input signals quickly and reliably (stably), an input signal is split into a first and second signal. The second signal is split into mutually orthogonal first and second subsignals which are recombined after the respective amplitudes thereof have been adjusted, The first signal is canceled by the third signal thereby obtained. The orthogonal subsignals can undergo amplitude adjustment independently, and the third signal obtained by recombining the subsignals after adjustment can become a cancellation signal having a really selected phase and amplitude over the first through fourth quadrants of the vector plane.

Delays on a common radio communications channel employed by plural mobile stations to communicate with a base station located in a corresponding geographical cell area are minimized by adapting transmission power based on traffic conditions. For lower traffic loads, a higher transmission power is permitted. For higher traffic loads, a lower power level is set. A transmit power level is determined using a desired signal ratio, such as a target CIR, a transmission path loss over the radio communications channel, and an interference value. One or more adaptive power parameters are also employed in that determination to adapt the open loop power control based on one or more current communications conditions and/or characteristics of the mobile station. For example, an adaptive power parameter may be a function of a current interference in a base station cell either alone or in combination with a current interference in one or more neighboring cells. The adaptive power parameter may also account for a type of data packet connection to be employed between the mobile station and the base station after random access, a mobile station's subscription, a current temperature of the mobile station, a current base station used by the mobile station, a current estimated path loss between the mobile station and base station, and/or other factors.

An off-channel leakage power monitor implemented in a transceiver (100) dynamically measures adjacent and alternate channel leakage power produced by nonlinearities in a transmitter (110) power amplifier (116). A main local oscillator (124), offset voltage-controlled oscillator (122), and second local oscillator (170) are adjusted to obtain on-channel power, adjacent channel power, and alternate channel power measurements using a measurement calculator (185) implemented in a digital signal processor (180) or as a gate array in a receiver (140). Once the off-channel leakage power measurements have been obtained, any number of techniques can be used to extract increased efficiency from the power amplifier (116) while maintaining acceptable linearity under changing operating conditions.

A pilot generation and detection system within a feed forward power amplifier that uses positive feedback to create a narrow bandwidth limit cycle is disclosed. The pilot system adjusts its frequency automatically to keep a desirable phase relationship between the pilot generation and detection. As a result, quadrature modulation/detection of the pilot used in prior approaches to ensure reliable estimates of the detected pilot power is unnecessary. This reduces the cost of the system. In addition, the pilot system turns the pilot amplitude `on` or `off` as needed. When the alignment of the second loop is good, the positive feedback will not have sufficient gain to maintain a limit cycle. As a result, the pilot will turn off when the second loop has converged. The pilot will return automatically as a by-product of the positive feedback if the second loop alignment degrades. Turning off the pilot when the second loop has converged reduces the pilot spurs appearing at the output of the feed forward amplifier. In addition, turning off the pilot reduces the power in the error amplifier, which in turn, allows the transistor size to be reduced.