Multiplex communications – Generalized orthogonal or special mathematical techniques – Fourier transform
Reexamination Certificate
2001-05-18
2004-04-27
Nguyen, Chau (Department: 2663)
Multiplex communications
Generalized orthogonal or special mathematical techniques
Fourier transform
C370S335000, C370S342000
Reexamination Certificate
active
06728203
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to networks and, more particularly, to systems and methods for selecting a cell in a wireless communications network.
At startup, a mobile terminal may perform a cell search operation to find, identify, and synchronize to a cell in the communications network. In a wideband code division multiple access (WCDMA) network, this cell search operation may consist of a three-stage pipeline process, as described, for example, in “Cell Search in W-CDMA,” by Yi-Pin Eric Wang et al., IEEE J. Select. Areas Commun., Vol. 18, No. 8, August 2000, pp. 1470-1482.
The goal of the three-stage pipeline process is to achieve time and code synchronization. In stage 1, the mobile terminal generates a slot boundary candidate. Stage 2 of the pipelined process receives the slot boundary candidate and identifies a frame boundary and scrambling code group pair. Finally, in stage 3, the mobile terminal uses the frame boundary-code group pair to identify a scrambling code. The mobile terminal may perform a verification and termination operation in stage 3 to determine a confidence score of the candidate scrambling code. When the mobile terminal detects a candidate with a high confidence score, the mobile terminal may perform a frequency acquisition operation. When a candidate having a high confidence score is not detected in stage 3, the mobile terminal continues the pipeline process.
BRIEF SUMMARY OF THE INVENTION
Systems and methods, consistent with the present invention, facilitate the selection of a cell in a wireless communications network.
In accordance with the invention as embodied and broadly described herein, a method for selecting a frequency error estimate in a wireless communications network is provided. The method includes generating a slot boundary candidate, identifying a frame boundary and scrambling code group for the slot boundary candidate, identifying a scrambling code from the identified scrambling code group, determining a frequency error estimate using the identified scrambling code, determining a detection metric, comparing the detection metric to a predetermined threshold, and selecting the frequency error estimate when the detection metric is greater than the predetermined threshold.
In another implementation consistent with the present invention, a system for selecting a frequency error estimate in a WCDMA system is provided. The system includes a first stage that generates a slot boundary candidate, a second stage that receives the slot boundary candidate and identifies a frame boundary and scrambling code group, a third stage that receives the scrambling code group and identifies a scrambling code, and a fourth stage that receives the scrambling code, determines a frequency error estimate using the scrambling code, generates a detection metric, and selects the frequency error estimate when the detection metric exceeds a threshold.
In yet another implementation consistent with the present invention, a four-stage pipelined system is disclosed. The pipelined system includes a first stage that detects a slot boundary, a second stage that receives the slot boundary and identifies a frame boundary and scrambling code group based on the slot boundary, a third stage that receives the frame boundary and scrambling code group and identifies at least one scrambling code based on the frame boundary and scrambling code group, and a fourth stage that receives the scrambling code and performs frequency acquisition and cell search verification and termination.
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Coats & Bennett P.L.L.C.
Hyun Soon-Dong
Nguyen Chau
Telefonaktiebolaget L.M. Ericsson
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