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US 5,644,591 AGranted
Method and apparatus for performing search acquisition in a CDMA communications system
AssigneeQUALCOMM Incorporated
InventorTodd R. Sutton
Life of this patent
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AssigneeQUALCOMM Incorporated
InventorTodd R. Sutton
Estimating the term…
A novel an improved method of acquisition in a spread spectrum communication system is presented. In the present invention, a large window of PN chip offset hypotheses are searched and if an energy signal is found that might indicate the presence of the pilot signal having one of the chip offsets of the large search window, then a search of a subset of offset hypotheses, or small window, is searched.
In a direct sequence spread spectrum receiver, a method for for processing a received signal, comprising the steps of;
An apparatus for selecting a synchronized demodulation sequence comprising:
A system for selecting a synchronized demodulation sequence comprising:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
With code phase acquisition: setting of search window, i.e. range of code offsets to be searched
With code phase acquisition: setting of lock conditions, e.g. threshold
With code phase acquisition: multi-step acquisition, e.g. multi-dwell, coarse-fine or validation
Relating to direct sequence modulation: featuring pilot assisted reception
Term ended 29 Jul 2014 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
I. Field of the Invention
The present invention relates to spread spectrum communications. More particularly, the present invention relates to a novel and improved method and apparatus for acquisition in spread spectrum communication environment.
II. Description of the Related Art
The features, objects, and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout and wherein:
FIG. 1 is a block diagram of the present invention;
FIG. 2 is an illustration of the energy versus chip offset for a fixed window;
In a spread spectrum communication system, a pilot signal is used to synchronize a mobile station in phase and frequency to the transmissions of a base station. In the exemplary embodiment, the spread spectrum communication system is a direct-sequence spread spectrum communication system. Examples of such systems are discussed in U.S. Pat. No. 5,056,109 and U.S. Pat. No. 5,103,459. In a direct-sequence spread spectrum communication system, the transmitted signals are spread over a frequency band greater than the minimum bandwidth necessary to transmit the information by modulating a carrier wave by the data signal, then modulating the resulting signal again with a wideband spreading signal. In a pilot signal, the data can be looked at as an all ones sequence.
The spreading signal is typically generated by a linear feedback shift register, the implementation of which is described in detail in the aforementioned patents. The spreading signal can be viewed as a rotating phasor of the form:
s(t)=Ae.sup.-.omega.t+.phi. (1)