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 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 cyclic prefix is added (328, 516) to the serial sequence to form a pilot symbol (330).
Claims25
-6. (canceled)
A method for receiving a pilot symbol in an single carrier frequency division multiple access (SC-FDMA) receiver comprising:
- removing a cyclic prefix from a received sequence to produce a modified sequence;
- transforming the modified sequence to a first frequency domain sequence according to a first transform;
- demapping a plurality of distributed subcarriers in the transformed modified sequence to extract a plurality of received pilot symbols;
- deriving an intermediate channel estimate for each of the plurality of received pilot symbols, based on one or more characteristics of each of the plurality of pilot symbols;
- and
- interpolating a final channel estimate based on the plurality of derived intermediate channel estimates.
A single carrier frequency division multiple access (SC-FDMA) receiver, comprising:
- a wireless interface comprising:
- first apparatus configured to remove a cyclic prefix from a received sequence to produce a modified sequence;
- second apparatus configured to transform a received sequence to a first frequency domain sequence;
- third apparatus configured to demap a plurality of distributed subcarriers in the first frequency domain sequence to extract a plurality of received pilot symbols;
- fourth apparatus configured to derive an intermediate channel estimate for each of the plurality of received pilot symbols, based on one or more characteristics of each of the plurality of pilot symbols;
- and
- fifth apparatus configured to interpolate a final channel estimate based on the plurality of derived intermediate channel estimates.
A method for extracting one or more pilot symbols within an Orthogonal Frequency Division Multiplexing (OFDM) system, comprising:
- receiving a sequence comprising a plurality of pilot symbols and data symbols interspersed in the frequency domain;
- extracting the plurality of pilot symbols and data symbols from the received sequence;
- estimating an intermediate channel response for each of the extracted pilot symbols;
- and
- interpolating an overall channel response based at least in part on the estimated intermediate channel response.
Wireless receiver apparatus configured to extract one or more pilot symbols from a wireless Orthogonal Frequency Division Multiplexing (OFDM) signal, comprising:
- first apparatus configured to receive a sequence comprising a plurality of pilot symbols and data symbols interspersed in the frequency domain;
- second apparatus configured to extract the plurality of pilot symbols and data symbols from the received sequence;
- third apparatus configured to estimate an intermediate channel response for each of the extracted pilot symbols;
- and
- fourth apparatus configured to interpolate an overall channel response based at least in part on the estimated intermediate channel response.
Dependencies are inferred from the claim text.