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Methods and apparatus for random access in multi-carrier communication systems

  • US 9,565,700 B2
  • Filed: 05/21/2013
  • Issued: 02/07/2017
  • Est. Priority Date: 03/09/2004
  • Status: Active Grant
First Claim
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1. In a multiple access wireless communication system having a plurality of base stations covering a plurality of cells, a method by a base station to determine a time delay associated with a mobile station using a random access subchannel, the method comprising:

  • allocating, within a communication channel, a random access (RA) subchannel selected from a plurality of frequency subchannels and a RA time slot selected from a plurality of time slots, the RA time slot and RA subchannel associated with the cell in which the base station is located;

    receiving a signal from a mobile station over the selected RA subchannel in the selected RA time slot;

    processing the received signal by;

    applying a Fast Fourier Transform (FFT) to the received signal to generate a transformed signal in the frequency domain;

    computing, in the frequency-domain, a dot-product between the transformed signal and an RA sequence specific to the cell in which the base station is located;

    analyzing the computed frequency-domain dot-product to identify the RA sequence carried in the received signal;

    computing, in the time-domain, a correlation between a time-shifted version of the received signal and the identified RA sequence; and

    analyzing the computed time-domain correlation to determine a time delay associated with the mobile station;

    identifying the mobile station associated with the RA sequence; and

    transmitting to the identified mobile station an indication of a time advance based on the determined time delay associated with the mobile station.

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