Nokia Mobile Phones Limited

Joe Dowling

Thomas J Kenney

Steven Daniel Gray

Ilkka Niva

Adam F Gould

Darin Yeoman

Ajith Mekkoth

This invention teaches methods, and circuits that operate in accordance with the methods, for improving the management and control of pilot channel sets for a CDMA mobile station. In one aspect a Priority Neighbor Search technique is provided, wherein a list of Priority Neighbor pilot channels is maintained and searched with a higher priority than the Neighbor Set pilot channels. In a further aspect this invention provides a Dropped Pilot Channel Search technique wherein a set is made of the last pilot channel or pilot channels dropped from the Active Set, wherein the dropped pilot channels are searched for some period of time with a higher priority than the Neighbor Set pilot channels. This invention also provides a High Priority Search Set feature which includes members of the Active Set, the Candidate Set, the Dropped Pilot Set, and the Priority Neighbor Set.

Prioritizing pilot set searching for a CDMA telecommunications system

In the front end of a CDMA cellular or broadband PCS mobile phone receiver, a switched bypass connection is provided to bypass the low noise amplifier, sending the received signal through an amplifier bypass connection. The amplifier bypass connection may include an attenuator. The switched bypass is activated by a control signal generated by a digital signal processor. The digital signal processor analyzes the received signal to detect and determine the relative contribution of the IMD interference to the total received signal power and, when the IMD interference exceeds a predetermined level, sends a control signal to bypass the low noise amplifier. Identification of the presence of IMD interference is by spectral estimation to discern when the mobile phone is in the presence of large near-band signals from an AMPS or other narrow-band base station which causes in-band IMD. In a preferred embodiment, the spectral estimation is performed by collecting a series of data samples from the received signal and, using a digital signal processor (DSP), computing a Discrete Fourier Transform (DFT) to generate frequency domain data, passing the data through a filter bank, then using a decision algorithm to determine whether or not there is sufficient IMD present in the received signal to bypass the LNA. If the IMD level is high enough to warrant bypass of the LNA, the DSP will provide a signal to an automatic gain control (AGC) block for controlling a variable gain amplifier (VGA) to compensate for gain loss due to bypass of the LNA.

Device and method for detection and reduction of intermodulation

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San Diego, CA, United States of America

Joe Dowling