Communication device and method for determining finger lock status in a radio receiver
First Claim
1. A method for controlling finger lock status in a radio receiver which receives signals subject to fading, the radio receiver including a plurality of receiver fingers and a combiner coupled to each receiver finger, the method comprising the steps of:
- receiving a signal at a receiver finger, the signal having an assumed average fade interval;
averaging the signal over an averaging time period which is longer than the assumed average fade interval, producing a filtered signal;
locking the receiver finger when a signal quality parameter for the filtered signal exceeds a lock threshold; and
unlocking the receiver finger when the signal quality parameter falls below an unlock threshold, the unlock threshold being above a noise floor of the receiver finger and less than the lock threshold.
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Accused Products
Abstract
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.
76 Citations
20 Claims
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1. A method for controlling finger lock status in a radio receiver which receives signals subject to fading, the radio receiver including a plurality of receiver fingers and a combiner coupled to each receiver finger, the method comprising the steps of:
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receiving a signal at a receiver finger, the signal having an assumed average fade interval; averaging the signal over an averaging time period which is longer than the assumed average fade interval, producing a filtered signal; locking the receiver finger when a signal quality parameter for the filtered signal exceeds a lock threshold; and unlocking the receiver finger when the signal quality parameter falls below an unlock threshold, the unlock threshold being above a noise floor of the receiver finger and less than the lock threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A communication device comprising:
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a plurality of assigned receiver fingers, each assigned receiver finger being initially designated as locked, each assigned receiver finger configured for receiving a spread spectrum communication signal including a pilot channel signal, each assigned receiver finger including; a traffic symbol decoder for producing a traffic signal in response to the spread spectrum communication signal; a pilot symbol decoder for decoding the pilot channel signal and detecting pilot symbols, the pilot symbol decoder producing a weighted channel estimate; a received signal strength indication (RSSI) circuit coupled to the pilot symbol decoder, the RSSI circuit sampling the pilot symbols and producing a pilot sample signal, the RSSI circuit including a filter for filtering the pilot sample signal and producing a filtered signal and a comparator for producing a lock indication when the filtered signal exceeds a lock threshold; and a combiner coupled to the plurality of receiver fingers, the combiner combining the traffic signal according to the weighted channel estimate from each respective assigned receiver finger in response to the lock indication from each respective assigned receiver finger. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification