Glenayre Electronics, Inc.

Marlo Rene Gothe

Steven John Bennett

Claudio Gustavo Rey

Kenneth Lee

Ognjen B Katic

Nino Pietro Ferrario

A physical channel estimator for a communication system using pilot symbols and an equalizer uses a model of the system in which the impulse response of the physical channel is considered separately from the impulse responses of the pulse shaping filters in the transmitter and receiver of the communication system. The system is modeled as if the signals were propagated first through both pulse shaping filters and then through the physical channel. To estimate the physical channel impulse response, known pilot symbols are transmitted and then sampled. The pilot symbol samples and the known impulse responses of the pulse shaping filters are then used to estimate the physical channel impulse response. In one embodiment, the physical channel impulse response is considered time-invariant over the estimation period and a sufficient number of pilot symbol samples are taken so that the system is overdetermined. A least squares method is then used to estimate the physical channel impulse response from the pilot symbol samples and the known responses of the pulse shaping filters. Further refinements include conditioning the estimated physical channel impulse response to improve performance in low SNR conditions and estimating a DC offset incurred from demodulating the received signal.

Physical channel estimator

A paging protocol includes header synchronization and system information segments containing information that allows a pager to conserve power. These segments can indicate a schedule of transmissions, and the channels of other transmissions. The pager can use this information to reduce the time the pager is in a high-power mode. In addition, the addresses are ordered so that the pager can more quickly determine whether a page is addressed to that particular pager. Further, the pager can activate circuitry in a sequenced manner to reduce peak power usage. The transmissions on different channels are synchronized in an offset manner so that the pager can scan one channel and switch to a next channel and immediately receive the start of a frame. Still further, the pager can be configured to perform narrowing searches during the initial acquisition process, which are then widened if no active channels are detected. If, after the widened search, still no active channels are detected, it is assumed that the pager is no longer in the service area. The pager enters an extended low-power mode to conserve power until the pager is moved back into the service area. The paging system and the pager also monitor the time between pages addressed to that pager and decrease the frequency of searches when the pager receives few pages. The paging system appropriately schedules a page when, eventually, a caller sends a page to that pager.

Method and apparatus for conserving power in a pager

A pattern detector adapted for wireless communication systems includes an error calculator, a comb filter, an averager, and a threshold detector. The pattern to be detected is a sequence of pilot signal patterns whose error calculation is relatively invariant with respect to frequency offset introduced by Doppler and the local oscillator. The pattern detector processes received input samples y.sub.k to determine an error signal from the input samples y.sub.k and estimated input samples y.sub.k. The estimated input samples y.sub.k are determined using an estimated channel impulse response. When a vector of the received input samples is 'aligned' with the expected header sync input samples, the level of the error signal is about equal to the level of the noise. The pattern detector determines the average level of the error signals for the last K error signals of each sample position E.sub.Kn within a pilot pattern, where K corresponds to the number of pilot patterns in a header sync pattern and n corresponds to the sample position. The pattern detector also determines the average level of the error signals E.sub.L corresponding to the last L received input samples, where L corresponds to the number of samples in a header sync sequence. When E.sub.Kn for a sample position is lower than a preselected threshold percentage of E.sub.L, the header sync pattern is deemed detected. Finally, the end of the header sync pattern is determined by the location of the minimum E.sub.Kn. This minimum is found by calculating, once the header is deemed detected, values for E.sub.Kn that are a certain number of samples past the last minimum.

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Vancouver, Canada

Marlo Rene Gothe