US 5,889,768 AGranted

Method of and apparatus for pilot channel acquisition

AssigneeMotorola, Inc.

InventorsBrian D. Storm, David J. Krause

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Abstract

A wireless communication device 100 acquires a pilot channel before an assigned slot when the wireless communication device is operating in the slotted mode of a CDMA system. The wireless communication device comprises a searcher receiver 107 that determines the short-term average pilot strength of active and neighbor pilot channels. Finger receivers 107 determine the long-term average pilot strength of the active and neighbor pilot channels. A logic and control circuit 113 assigns the finger receivers to the pilot channels according to their short-term average pilot strength, determines if the long-term average pilot strength of a neighbor channel is greater than the active pilot channel's pilot strength, and determines to hand off to the neighbor pilot channel with the greater long-term average pilot strength. Moreover, an early detection correlation length can be dynamically adjusted according to the pilot strength of the active pilot channel to shorten the pilot acquisition process.

Claims21

Dependent claims

A method of acquiring a pilot channel in a Code-Division Multiple Access system, the method comprising the steps of:

setting an early detection threshold (EDT) parameter to a first value;
determining a pilot strength of an active pilot channel;
determining whether the active pilot channel's pilot strength is less than the first value;
re-setting the EDT parameter to a second value when the active pilot channel's pilot strength is not less than the first threshold value;
determining whether there is at least one neighbor pilot channel in a neighbor set;
and
sweeping the at least one neighbor pilot channel when there is at least one neighbor pilot channel, the step of sweeping the at least one neighbor pilot channel including the substeps of,
performing a correlation at a particular chip offset of the at least one neighbor pilot channel,
determining a pilot strength at an early detection correlation length at the particular chip offset,
determining whether the pilot strength at the early detection correlation length is less than the EDT parameter, and
terminating the correlation at the particular chip offset when the pilot strength at the early detection correlation length is less than the EDT parameter;
assigning a finger receiver to the at least one neighbor pilot channel;
re-determining the pilot strength of the active pilot channel;
re-determining the pilot strength of the at least one neighbor pilot channel that has a finger receiver assigned;
and
handing off to the at least one neighbor pilot channel that has a finger receiver assigned when the re-determined pilot strength of the at least one neighbor pilot channel that has a finger receiver assigned is greater than the re-determined pilot strength of the active pilot channel.

13 more elements

A method of acquiring a pilot channel in a Code-Division Multiple Access system, the method comprising the steps of:

determining whether there is at least one neighbor pilot channel in a neighbor set;
sweeping the neighbor pilot channels in the neighbor set when there is at least one neighbor pilot channel including the substep of determining the pilot strength of the neighbor pilot channels;
assigning finger receivers to the neighbor pilot channels according to pilot strength;
determining a greatest neighbor pilot strength of the neighbor pilot channels that have finger receivers assigned;
determining a pilot strength of an active pilot channel;
determining if the greatest neighbor pilot strength is greater than the active pilot channel's pilot strength;
and
handing off to the neighbor pilot channel with the greatest neighbor pilot strength when the greatest neighbor pilot strength is greater than the active pilot channel's pilot strength.

5 more elements

A wireless communication device for acquiring a pilot channel in a Code-Division Multiple Access system, the wireless communication device comprising:

a searcher receiver for sweeping an active pilot channel and a plurality of neighbor pilot channels, and for determining the short-term average pilot strength of the active pilot channel and each of the neighbor pilot channels;
a plurality of finger receivers for determining the long-term average pilot strength of the active pilot channel and the neighbor pilot channels;
and
a logic and control circuit for assigning the plurality of finger receivers to the active pilot channel and to the neighbor pilot channels according to their short-term average pilot strength, for determining the greatest long-term average pilot strength of the neighbor pilot channels, for determining if the greatest long-term average pilot strength is greater than the active pilot channel's long-term average pilot strength, and for determining to hand off to the neighbor pilot channel with the greatest long-term average pilot strength when the greatest long-term average pilot strength is greater than the active pilot channel's long-term average pilot strength.

1 more element

A wireless communication device for acquiring a pilot channel in a Code-Division Multiple Access system, the wireless communication device comprising:

a searcher receiver for sweeping an active pilot channel and a plurality of neighbor pilot channels, and for determining the short-term average pilot strength of the active pilot channel and each of the neighbor pilot channels;
a plurality of finger receivers for determining the long-term average pilot strength of the neighbor pilot channels;
and
a logic and control circuit for filtering the short-term average pilot strength of the active pilot channel and providing a filtered short-term average pilot strength, assigning the plurality of finger receivers to the neighbor pilot channels according to their short-term average pilot strength, for determining the greatest long-term average pilot strength of the neighbor pilot channels, for determining if the greatest long-term average pilot strength is greater than the active pilot channel's filtered short-term average pilot strength, and for determining to hand off to the neighbor pilot channel with the greatest long-term average pilot strength when the greatest long-term average pilot strength is greater than the active pilot channel's filtered short-term average pilot strength.

1 more element

A wireless communication device for acquiring a pilot channel in a Code-Division Multiple Access system, the wireless communication device comprising:

a searcher receiver for sweeping an active pilot channel and a plurality of neighbor pilot channels, and for determining the short-term average pilot strength of the active pilot channel and each of the neighbor pilot channels;
a plurality of finger receivers for determining the long-term average pilot strength of the neighbor pilot channels;
and
a logic and control circuit assigning the plurality of finger receivers to the neighbor pilot channels according to their short-term average pilot strength, for determining the greatest long-term average pilot strength of the neighbor pilot channels, for determining if the greatest long-term average pilot strength is greater than the active pilot channel's short-term average pilot strength, and for determining to hand off to the neighbor pilot channel with the greatest long-term average pilot strength when the greatest long-term average pilot strength is greater than the active pilot channel's short-term average pilot strength.

1 more element

Dependencies are inferred from the claim text.