Fast fourier transform processing in an OFDM system
AssigneeQUALCOMM Incorporated
InventorKevin Cousineau
Life of this patent
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Abstract
An FFT processor for an OFDM receiver includes multiple interrelated operational blocks. The FFT processor is configured to perform data demodulation, channel estimation, and fine timing acquisition on received OFDM symbols. The FFT processor incorporates a pipelined FFT engine using a memory architecture shared with channel estimation and demodulation blocks. The combination of the shared memory structure and the pipelined FFT operation enable the channel estimation and demodulation processing to be completed during the time used to capture the next received symbol.
Claims32
A signal processing apparatus for processing Orthogonal Frequency Division Multiplex (OFDM) symbols, the apparatus comprising:
- a memory architecture including a plurality of memory banks;
- a demodulation block configured to receive samples of the OFDM symbols and accumulate the samples into a plurality of interlace memory within the memory architecture;
- and
- a computational block configured to perform a frequency domain transform on at least one of the plurality of interlace memory.
A signal processing apparatus for processing Orthogonal Frequency Division Multiplex (OFDM) symbols, the apparatus comprising:
- a memory architecture comprising a plurality of memory banks;
- a demodulation block configured to receive symbols corresponding to an OFDM symbol and accumulate symbol sample data in sample memory within the memory architecture, the demodulation block accumulating P distinct samples for each of M OFDM interlaces, where P represents the number of subbands per interlace;
- a Fast Fourier Transform (FFT) engine configured to perform a P-point FFT operation;
- and
- a channel estimator coupled to the memory architecture and the FFT engine, and configured to generate a channel estimate based on a P-point FFT of a plurality of accumulated pilot samples.
A signal processing apparatus for processing Orthogonal Frequency Division Multiplex (OFDM) symbols, the apparatus comprising:
- means for storing a plurality of values;
- means for demodulating a plurality of received OFDM samples and accumulating each of the plurality of received OFDM samples in one of a plurality of interlace storage portions within the means for storing a plurality of values;
- and
- means for transforming the plurality of OFDM samples stored in at least one of the plurality of interlace storage portions to a frequency domain representation.
A method of processing Orthogonal Frequency Division Multiplex (OFDM) symbols, the method comprising:
- demodulating received samples of a first OFDM symbol to generate demodulated samples;
- storing the demodulated samples in a memory architecture;
- determining a channel estimate based on the demodulated samples prior to demodulating all received samples of a second OFDM symbol;
- and
- determining encoded values corresponding to a plurality of subbands of an interlace from a plurality of OFDM interlaces based on the demodulated samples.
Computer-readable medium encoded with a computer program to perform the steps comprising:
- demodulating received samples of a first OFDM symbol to generate demodulated samples;
- storing the demodulated samples in a memory architecture;
- determining a channel estimate based on the demodulated samples prior to demodulating all received samples of a second OFDM symbol;
- and
- determining encoded values corresponding to a plurality of subbands of an interlace from a plurality of OFDM interlaces based on the demodulated samples.
Dependencies are inferred from the claim text.