Method for searching pilot signals to synchronize a CDMA receiver with an associated transmitter

• US 8,315,294 B2
• Filed: 03/28/2011
• Issued: 11/20/2012
• Est. Priority Date: 02/23/2000
• Status: Expired due to Fees

• Current Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Original Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Inventors: Proctor, James A. Jr., Rouphael, Antoine J., Hoffmann, John E., Nelson, George R. Jr.
• Primary Examiner(s): Vo, Don N
• Application Number:
  US13/073,594
• Publication Number:
  US 20110170493A1
• Time in Patent Office: 603 Days
• Field of Search: 375/219
• US Class Current: 375/219
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 1/70775 Multi-dwell schemes, i.e. multiple accumulation times
• CPC Class Codes: H04B 1/7103 the interference being multiple access interference
• CPC Class Codes: H04B 2201/70701 featuring pilot assisted reception
• CPC Class Codes: H04B 7/086 using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
• CPC Class Codes: H04L 2027/0057 quadrature phase
• CPC Class Codes: H04L 2027/0087 Out-of-band signals, (e.g. pilots)
• CPC Class Codes: H04L 27/2273 associated with quadrature demodulation, e.g. Costas loop
• CPC Class Codes: H04W 56/001 Synchronization between nodes

Abstract

A method for synchronizing a CDMA receiver to a transmitter when an adaptive antenna is utilized to receive transmitted data, wherein a receiving antenna system is adapted between a 360° reception angle pattern (i.e., an omni-directional pattern) and a fixed reception angle (i.e., a directional pattern) by permitting the receiver to identify a pilot signal having the largest magnitude. The receiver minimizes interference from other pilot signals by steering antenna pattern nulls toward other transmitters. As a result, the time required for the receiver to acquire a valid pilot signal is significantly reduced.

Claims

1. An apparatus for searching for a pilot signal and optimizing reception of the pilot signal in wireless communications, comprising:

a steerable antenna comprising a plurality of antenna elements;

phase shifters coupled to respective antenna elements, the phase shifters configured to steer the antenna;

a pseudorandom noise (PN) sequence generator, configured to generate a PN sequence as output;

a modulator, configured to receive demodulated in-phase (I) and quadrature (Q) signals and modulate the I and Q signals with the output of the PN sequence generator;

a first integrator configured to integrate the modulated I signal;

a second integrator configured to integrate the modulated Q signal;

a first squarer configured to square an output of the first integrator;

a second squarer configured to square an output of the second integrator;

a summer configured to add outputs of the first and second squarers;

a third integrator configured to integrate an output of the summer; and

a threshold circuit configured to set a plurality of thresholds and determine if an output of the third integrator exceeds at least one of the thresholds.

2. The apparatus of claim 1, further comprising:

a first memory configured to store a phase angle;

a digital-to-analog converter configured to receive the phase angle and supply antenna direction setting information to the phase shifters;

a second memory configured to store a frequency offset;

a frequency incrementing circuit configured to increment the frequency offset by a predetermined offset increment; and

a PN offset circuit configured to apply a PN offset to the PN sequence from the PN sequence generator;

wherein the apparatus detects the pilot signal by incrementing the frequency offset, incrementing the PN offset, and comparing the output of the third integrator to the thresholds, and maximizes a magnitude of the detected pilot signal by steering the antenna.