Mitigation of negative delay via half CP shift
AssigneeParallel Wireless, Inc.
InventorsAjay Sharma, Somasekhar Pemmasani
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Abstract
A receiver performing a half cyclic prefix (CP) shift on received subframes is disclosed, comprising: an analog to digital conversion (ADC) module; a cyclic prefix (CP) removal module coupled to the ADC module configured to retain a portion of cyclic prefix samples; a fast Fourier transform (FFT) module configured to receive samples from the cyclic prefix removal module, and to perform a FFT procedure on the received samples using a FFT window, the FFT window being shifted ahead based on the retained portion of cyclic prefix samples, to output an orthogonal frequency division multiplexed (OFDM) symbol; and a rotation compensation module coupled to the FFT module, the rotation compensation module configured to perform phase de-rotation of the OFDM symbol.
Claims15
A receiver, comprising:
- an analog to digital conversion (ADC) module performing ADC on a slot contained in a subframe of an OFDM radio frame to generate a sample sequence;
- a cyclic prefix (CP) removal module coupled to the ADC module configured to retain a portion of cyclic prefix samples and performing CP sample removal on the plurality of samples to generate a CP-removed sample sequence;
- a fast Fourier transform (FFT) module receiving samples from the cyclic prefix removal module, and performing a FFT procedure on the received samples using a shifted FFT window, the FFT window being shifted ahead based on the retained portion of cyclic prefix samples, to output an orthogonal frequency division multiplexed (OFDM) symbol;
- and
- a rotation compensation module coupled to the FFT module, the rotation compensation module performing phase de-rotation of the OFDM symbol, wherein de-rotating the symbol is done by multiplying the symbol by a complex conjugate of a phase ramp e−j2ft.
A method, comprising:
- receiving an orthogonal frequency division multiplexed (OFDM) radio frame, the OFDM radio frame containing a subframe, the subframe containing a slot, wherein the OFDM radio frame is a 5G radio frame or an LTE radio frame;
- performing analog to digital conversion (ADC) on the slot to generate a sample sequence;
- performing cyclic prefix (CP) sample removal on the plurality of samples to generate a CP-removed sample sequence;
- performing a fast Fourier transform (FFT) on the OFDM symbol using a shifted window to generate a symbol;
- and
- performing a de-rotation of the symbol by multiplying the symbol by a complex conjugate of a phase ramp e31 j2ft,
- wherein the CP-removed sample sequence contains a portion of a cyclic prefix of the sample sequence.
Dependencies are inferred from the claim text.