Motorola Corporation

Bradley B Bakke

John William Arens

Daniel Richard Tayloe

Keith Andrew Olds

Christopher N Kurby

Michael William Krutz

Mark S Frank

Michael J Andresen

Paul R Christian

R Travis Jones

Dariusz Andrzej Blasiak

Daniel T Buhmann

A Corbett Kull

Victoria Francesca Buenviaje

A method for system acquisition for a subscriber unit (112) in a satellite communication system (100) maximizes life of a battery (320) of a battery-powered subscriber unit. A receiver (304) of the subscriber unit is energized only when ring bursts are expected from satellites in the system, serving to minimize consumption of battery power. During just two scans, the subscriber unit acquires enough information to enable it to identify the best beam for monitoring for a ring alert and to predict the nearby beams most likely to carry a ring alert targeted for the subscriber unit. From the received information, the subscriber unit can also perform necessary processes such as passive geolocation. The subscriber unit then enters a low-power standby mode, energizing the receiver only long enough to detect the best beam to scan for a ring alert targeted for the subscriber unit.

Method and apparatus for system acquisition for a subscriber unit

In cellular communication systems, hand-offs are performed to maintain links as subscriber units (110) and beams move relative to each other. The hand-off determination procedure (500) is performed in overlap regions (240, 340). Candidate beams are identified and hand-off types are determined based on the satellite (120) associated with the candidate beam. Thresholds are established and changed to optimize a hand-off request determination procedure (500). Two hand-off types are considered. An inter-satellite hand-off is requested (514) when the current beam and the candidate beam are on different satellites (120). An intra-satellite hand-off is requested (510) when the current beam and the candidate beam are on the same satellite (120). Thresholds are dynamically changed and algorithms are used to minimize the number of inter-satellite hand-offs.

Method and apparatus for dynamically controlling hand-off thresholds in

An emergency handoff method (50) reroutes or redirects communications from one channel in a cell (105) to another channel in the same cell (105) or a different cell (107). Handoff is initiated by a subscriber unit (SU) (100) when the SU (100) determines that an emergency handoff is needed. Once a new channel is needed, the SU (100) chooses a new, available channel to transfer its communication. After selecting an available channel, the SU (100) acquires the available channel. The servicing satellite which is providing the available channel then makes the constellation of satellites reroute or redirect the call data or the communication packets across the new channel to the SU (100).

Emergency handoff method of redirecting calls in a satellite

A method for a radio frequency communication unit (110) (CU) to hand off from a losing node (120) to a gaining node (122) estimates a gaining node uplink time (210) and a gaining node uplink frequency (212), which the gaining node uplink signal comprises. During handoff, the CU (110) ceases communications with the losing node (120) and immediately begins communications with the gaining node (122) using the uplink time and uplink frequency. A CU apparatus (300) uses a processor (302) for carrying out calculations necessary for estimating the gaining node uplink time and frequency. Information necessary for the calculations, such as a downlink signal time-of-arrival and Doppler offset, are collected by a CU receiver (306). The CU receiver (306) and a CU transmitter (304) are used to support downlink signals (142) and uplink signals (140), respectively, between the CU (110) and a node (120, 122).

Method and apparatus for inter-node handoff of a radio frequency

A TDMA signal of frames of a nominal duration and having time slots is demodulated (120, 150, 160). A time slot assignment circuit (170) assigns and re-assigns time slots in a present and next frame based on TDMA control information. A real-time timing control circuit (180) determines a recovered-data duration for production of recovered data by a data decoder (190). The data decoder (190) produces the recovered-data during the receive-data duration by time compression or expansion during the next frame when a different time slot is re-assigned by the time slot re-assignment circuit (170).

Communication device with variable frame processing time

A burst detector (140) detects the occurrence of a burst in a signal receiver. A filter (220) having an impulse response characteristic of an expected burst filters a received signal. A subtractor (230) subtracts a filtered version of the received signal from a delayed and filtered version of the received signal to provide a detection signal. A burst edge detector (250) detects a leading edge of the burst based on the detection signal.

Method and apparatus for burst detecting

The present invention provides an apparatus for symbol clock recovery from a received signal having wide range of frequency errors or offsets. Magnitudes of received inphase and quadrature sampled signals are determined (210). These magnitudes are summed and distributed (227) into accumulator registers (231, 232, 233, 235, 237, 239) for accumulating sums of the first and second signals for each sample time and substantially over a length of an expected burst. A maximum-minimum determination circuit (240) chooses the sample time having a largest or smallest sum to provide a recovered clock signal (270). The carrier could then be recovered (260), and a downsampler (250) downsamples the received inphase and quadrature signals based on the recovered clock signal.

Growing community of inventors

Lake in the Hills, IL, United States of America

Bradley B Bakke