Motorola Corporation

Michael A Eberhardt

Colin D Frank

Phillip D Rasky

Michael J Carney

Brian David Storm

Christopher John Becker

David J Krause

Christopher P La Rosa

Christopher P Larosa

William F Taranowski

Christopher J Becker

An apparatus (100) maintains a Pilot Set in a digital communication system that utilizes Code Division Multiple Access. The apparatus comprises a logic and control circuit (113) for providing instructions to a searcher receiver (109). The searcher receiver, in response to the instructions, sequentially scans active pilots, then candidate pilots, and then pre-candidate pilots. The scan of the pre-candidate pilots continues until all but a predetermined number of pre-candidate pilots have been promoted or demoted. Then the searcher receiver alternately scans the predetermined number of pre-candidate pilots and the neighbor pilots. The searcher receiver terminates alternate scans of the predetermined number of pre-candidate pilots and the neighbor pilots when a one of the neighbor pilots is promoted, and resumes the scan of the pre-candidate pilots.

Method of and apparatus for pilot set maintenance

A RAKE receiver (112) includes a plurality of fingers (122, 124, 126, 128). Each finger includes a demodulator (402) for demodulating a ray of a multipath signal and a time tracking circuit (404) for controlling the time position of the finger in accordance with time position of the ray. A low delay-spread condition is detected and the positions of two adjacent fingers are controlled to prevent convergence of two or more fingers about a common time position. By maintaining finger timing separation, path diversity is exploited by the RAKE receiver even during the low delay-spread condition to improve receiver performance.

Rake receiver and finger management method for spread spectrum

A communication device (100) includes a plurality of receiver fingers (112, 114, 116) for receiving a spread spectrum communication signal. Each receiver finger includes a received signal strength indication (RSSI) circuit (400). The RSSI circuit (400) includes an energy calculator (406) and a filter (410, 412) for producing a filtered signal which indicates signal quality. A first comparator (414) produces a primary lock indication when the filtered signal exceeds a primary lock threshold. A second comparator (418) produces a secondary lock indication when the filtered signal exceeds a secondary lock threshold. The bandwidth of the RSSI circuit (400) can be varied between a first bandwidth for providing the primary lock indication for traffic channel decoder and a second bandwidth for providing the secondary lock indication for the power control bit decoder. This allows performance to be tailored to the individual requirements of the traffic channel decoding and the power control channel decoding.

Time-shared lock indicator circuit and method for power control and

A communication device (100) includes a plurality of receiver fingers (112, 114, 116) for receiving a spread spectrum communication signal. Each receiver finger includes a received signal strength indication (RSSI) circuit (130). The RSSI circuit (130) includes a filter (135) for filtering a pilot sample signal and producing a filtered signal. A comparator (144) producing a lock indication when the filtered signal exceeds lock threshold. A combiner (118) combines the traffic signal from each receiver finger in response to the lock indication from each finger. The unlock threshold for the finger is reduced to a level above the noise floor of the receiver finger, to reduce the likelihood of a finger unlocking during a fade. Also traffic symbols are immediately combined after a finger assignment using a weighted channel estimate to permit assigning a finger as locked.

Communication device and method for determining finger lock status in a

Growing community of inventors

Hanover Park, IL, United States of America

Michael A Eberhardt