Pilot signal in an fdma communication system
AssigneeApple Inc.
InventorJames W. McCoy
Life of this patent
Estimating the term…
Abstract
Methods (500, 800) and corresponding systems (100, 200, 300, 400, 900) for generating a pilot symbol (330) include providing an M-point parallel transform sequence that is a discrete Fourier transform of a CAZAC sequence (312, 504-508). The M-point s parallel transform sequence (312) is distributed (316, 510) to a set of M subcarriers among N subcarriers to form an N-point frequency-domain sequence (318) wherein the M subcarriers are evenly spaced apart. An N-point inverse fast Fourier transform (320, 512) is performed to convert the N-point frequency-domain sequence to an N-point time-domain sequence (322). The N-point time-domain sequence is converted (324, 514) to a serial sequence (326), and a to cyclic prefix is added (328, 516) to the serial sequence to form a pilot symbol (330).
Claims32
1-6. (canceled)
A method for generating a transmit sequence in a single carrier frequency division multiple access (SC-TDMA) transmitter, comprising:
- generating a first time domain sequence, the first time domain sequence having a constant amplitude and zero autocorrelation properties;
- transforming the first time domain sequence to a first frequency domain sequence according to a first transform;
- distributing the first frequency domain sequence among a subset of subcarriers among a plurality of subcarriers in a second frequency domain sequence;
- transforming the second frequency domain sequence to a second time domain sequence;
- and
- adding a cyclic prefix to the second time domain sequence to form a transmit sequence.
A single carrier frequency division multiple access (SC-FDMA) transmitter, comprising:
- a wireless interface, the wireless interface configured to communicate with a wireless communications device, the wireless interface comprising:
- a first transform module configured to transform a first time domain pilot sequence to a first frequency domain pilot sequence;
- a distribution module configured to distribute the first frequency domain pilot sequence among a subset of a plurality of subcarriers in a second frequency domain sequence;
- a second transform module configured to transform the second frequency domain sequence to a second time domain sequence;
- a prefix module, configured to add a cyclic prefix to the second time domain sequence to form a transmit sequence;
- a processor;
- and
- a computer readable apparatus having a storage medium with at least one computer program stored thereon, the at least one computer program configured to, when executed on the processor:
- generate the first time domain sequence, the first time domain sequence having a constant amplitude and zero autocorrelation properties;
- and
- cause one or more transmissions of the transmit sequence.
A method of incorporating one or more pilot symbols with for use within an Orthogonal Frequency Division Multiplexing (OFDM) system, comprising:
- generating a pilot symbol sequence, the pilot symbol sequence having one or more predefined characteristics;
- transforming the pilot symbol sequence to a first frequency domain sequence according to a Fourier Transform;
- distributing the first frequency domain sequence among a first subset of a plurality of subcarriers in a second frequency domain sequence;
- distributing a frequency domain data sequence comprising user data among a second subset of subcarriers among the plurality of subcarriers in the second frequency domain sequence;
- transforming the second frequency domain sequence to a second time domain sequence according to an Inverse Fourier Transform;
- adding a cyclic prefix to the second time domain sequence to form a transmit sequence;
- and
- transmitting the transmit sequence.
A single carrier frequency division multiple access (SC-FDMA) transmitter, comprising:
- a wireless interface comprising:
- first apparatus configured generate the first time domain sequence, the first time domain sequence having a constant amplitude and zero autocorrelation properties;
- and
- second apparatus configured to transform a first time domain sequence to a first frequency domain sequence;
- third apparatus configured to distribute the first frequency domain sequence among a subset of a plurality of subcarriers in a second frequency domain sequence;
- fourth apparatus configured to transform the second frequency domain sequence to a second time domain sequence;
- fifth apparatus configured to add a cyclic prefix to the second time domain sequence to form a transmit sequence for transmission over the wireless interface.
Wireless Orthogonal Frequency Division Multiplexing (OFDM) apparatus, comprising:
- first apparatus configured to generate a pilot symbol sequence, the pilot symbol sequence having one or more predefined characteristics;
- second apparatus configured to transform the pilot symbol sequence into a first frequency domain sequence according to a Fourier Transform;
- third apparatus configured to distribute the first frequency domain sequence among a first subset of a plurality of subcarriers in a second frequency domain sequence;
- fourth apparatus configured to distribute a frequency domain data sequence comprising user data among a second subset of subcarriers among the plurality of subcarriers in the second frequency domain sequence;
- fifth apparatus configured to transform the second frequency domain sequence into a second time domain sequence according to an Inverse Fourier Transform;
- and
- sixth apparatus configured to add a cyclic prefix to the second time domain sequence to form a transmit sequence.
Dependencies are inferred from the claim text.