Lucent Technologies Inc.

Neil E Bernstein

Wen-Yi Kuo

Carl Francis Weaver

Martin Howard Meyers

Xiao C Bernstein

Xiao Wang

Xiao Cheng Wu

Inter-frequency handoffs in a CDMA or other wireless communication system are controlled using a noise-limited coverage trigger metric which is able to distinguish between same-frequency cell boundaries and other-frequency cell boundaries in the system. The trigger metric may be generated as a function of an average signal-to-noise measure for pilot signals received at a mobile station of the system and a linear sum of the signal-to-noise measures. The signal-to-noise measures may be generated in the mobile station and included in messages transmitted from the mobile station to one or more base stations of the system. The trigger metric is used to control a handoff from a current frequency to a new frequency in an ongoing call. The trigger metric may alternatively be based on a measure of mobile receive power alone. Other aspects of the invention reduce unnecessary searching for a new frequency and decrease the likelihood of &ldquo;ping-ponging&rdquo; from a current frequency to a new frequency by providing additional checks in the handoff process. For example, receive power and pilot signal-to-noise measures may be generated at a mobile station for both current and new frequencies. The mobile station then continues to operate at the current frequency as long as certain predetermined threshold conditions based on the measures are satisfied.

Methods and apparatus for inter-frequency handoff in a wireless communication system

A method and system that minimizes pilot signal overlap and radio frequency (&ldquo;RF&rdquo;) interference by estimating changes in pilot coverage for different traffic channel loading and power conditions. Once base stations are positioned, a terminal for measuring received pilot signal strengths, such as a mobile station or pilot scanner, is used to collect and generate the baseline pilot survey data, which is then stored on a disk or tape. Base station transmit pilot E,/I,s, i.e., traffic channel loads on forward links, are also stored on disk or tape. The invention uses two adjustment factors associated with transmit power and traffic channel loading to optimize for different RF conditions, specifically for different base station transmit power or forward link loading conditions. For each RF condition, the methodology calculates the changes in the baseline pilot survey data. This reflects what E,/I,s a mobile station would receive under the given conditions. The systems engineer collects a set of optimized base station power settings for each of the different traffic channel load conditions. One of these optimized power settings is then selected by the systems engineer for each of the base stations.

Method and apparatus for estimating pilot coverages

Methods and apparatus for interfrequency handoff in a wireless communication system

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Short Hills, NJ, United States of America

Neil E Bernstein