Methods and apparatus for random access in multi-carrier communication systems
First Claim
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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Accused Products
Abstract
A method at a base station of determining a time delay associated with a mobile station in a multiple access wireless communication system. A signal is received from a mobile station over a selected random access subchannel in a selected random access time slot. A Fast Fourier Transform is applied to the received signal to generate a transformed signal in the frequency domain. The transformed signal is then processed in the frequency domain by computing a dot-product to identify a random access sequence carried in the received signal. The received signal is then processed in the time domain by computing a correlation between a time-shifted version of the received signal and the identified random access sequence to determine a time delay associated with the mobile station.
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Citations
12 Claims
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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:
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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. - View Dependent Claims (2, 3, 4, 9, 10)
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5. In a multiple access wireless communication system having a plurality of base stations covering a plurality of cells, a base station configured to communicate with a mobile station over 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, the base station comprising:
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a receiver configured to; receive a signal from a mobile station over the selected RA subchannel in the selected RA time slot; and a processor configured to process 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; analyzing the computed time-domain correlation to determine a time delay associated with the mobile station; and identifying the mobile station associated with the RA sequence; and a transmitter configured to transmit to the identified mobile station an indication of a time advance based on the determined time delay associated with the mobile station. - View Dependent Claims (6, 7, 8, 11, 12)
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Specification