Time-shared lock indicator circuit and method for power control and traffic channel decoding in a radio receiver

• US 5,930,288 A
• Filed: 12/20/1996
• Issued: 07/27/1999
• Est. Priority Date: 05/06/1996
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Eberhardt, Michael A.
• Primary Examiner(s): Ghebretinsae, Temesghen
• Application Number:
  US08/770,468
• Time in Patent Office: 949 Days
• Field of Search: 375/200, 375/205, 375/208, 375/317, 375/316, 370/209, 455/65, 455/506
• US Class Current: 375/148
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 1/7117 Selection, re-selection, allocation or re-allocation of paths to fingers, e.g. timing offset control of allocated fingers
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04W 52/225 Calculation of statistics, e.g. average, variance
• CPC Class Codes: H04W 52/228 using past power values or information
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity
• CPC Class Codes: H04W 52/56 Detection of errors of TPC bits

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 (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.

Claims

1. A communication device, comprising:

a pilot signal despreader;

a traffic channel combiner;

a power control bit decoder;

a time shared lock indicator circuit coupled to the traffic channel combiner and the power control bit decoder, the time shared lock indicator circuit detecting pilot symbols and providing a primary lock indication for use by the traffic channel combiner and detecting pilot symbols and providing a secondary lock indication for use by the power control bit decoder; and

a controller for controlling the time shared lock indicator circuit.

2. A communication device as recited in claim 1 wherein the time shared lock indicator circuit provides the primary lock indication at a first rate and provides the secondary lock indication at a second rate, the second rate being faster than the first rate.

3. A communication device as recited in claim 1 further comprising a plurality of receiver fingers for detecting traffic symbols and power control symbols, each of the plurality of receiver fingers including an associated time shared lock indicator circuit, the traffic channel combiner being coupled to the plurality of receiver fingers for combining traffic symbols from respective receiver fingers in response to a respective primary lock indication received from each respective receiver finger, the power control bit decoder being coupled to the plurality of receiver fingers for decoding power control bits from respective receiver fingers in response to a respective secondary lock indication received from each respective receiver finger.

4. A communication device as recited in claim 3 wherein the time shared lock indicator circuit provides the primary lock indication when a long-term average measurement of pilot signal energy exceeds a first predetermined threshold and the time shared lock indicator circuit provides the secondary lock indication when a short-term average measurement of pilot signal energy exceeds a second predetermined threshold.

5. A communication device comprising:

a plurality of receiver fingers configured for receiving a spread spectrum communication signal including a pilot channel signal, each receiver finger including;

a pilot symbol despreader for despreading the pilot channel signal and detecting pilot symbols;

a received signal strength indication circuit coupled to the pilot symbol despreader, the received signal strength indication circuit having a variable bandwidth including a first bandwidth and a second bandwidth, the first bandwidth being less than the second bandwidth, the received signal strength indication circuit producing a primary lock indication when a received signal quality exceeds a first predetermined threshold at the first bandwidth and producing a secondary lock indication when the received signal quality exceeds a second predetermined threshold at the second bandwidth; and

a controller coupled to the plurality of receiver fingers for controlling lock status of the plurality of receiver fingers in response to the primary lock indication and the secondary lock indication.

6. A communication device as recited in claim 5 further comprising a combiner coupled to the plurality of receiver fingers, the combiner combining a traffic signal from each respective assigned receiver finger in response to the primary lock indication from each respective assigned receiver finger.