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US 2010/0061474 A1Published application
Fft spreading among selected ofdm sub-carriers
AssigneeNXP B.V.
InventorCharles Razzell
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AssigneeNXP B.V.
InventorCharles Razzell
Estimating the term…
An improved communications system for frequency-selective fading channels spreads the data-bearing modulation symbols across many OFDM sub-carriers using a discrete Fourier transform (FFT) at the transmitter, and despreads them using an inverse discrete Fourier transform (IFFT) at the receiver. An IFFT is included at the transmitter to form the OFDM symbols in the usual way, and a corresponding FFT is used at the receiver for the frequency-domain processing of the received signal. The difference is, the size of the FFT used for spreading at the transmitter is smaller than that of an IFFT used just after the FFT to create the OFDM symbols for transmission. This results in improved bit-error-rate, similar to single carrier block transmission (SCBT), while retaining the frequency domain benefits of conventional OFDM, e.g., low out of band emissions and the ability to control the power spectral density using active interference cancellation and other frequency-domain techniques. The improved frequency diversity is especially useful in the higher data rate modes of WLAN or WiMedia Physical Layer Standards, and in other cases where low redundancy forward error correction is employed.
An improved orthogonal frequency division multiplexing (OFDM) communications system, including an inverse fast Fourier transform (IFFT) device in a transmitter to form OFDM symbols, and a corresponding fast Fourier transform (FFT) device at a receiver for frequency-domain processing of a received signal, the improvement comprising:
A transmitter method for improving bit-error-rate (BER) performance in an orthogonal frequency division multiplexing (OFDM) communications system such that low redundancy forward error correction in high data rate applications, comprising:
A receiver method for improving bit-error-rate (BER) performance in an orthogonal frequency division multiplexing (OFDM) communications system such that low redundancy forward error correction in high data rate applications, comprising:
A communications system method for improving bit-error-rate (BER) performance in an orthogonal frequency division multiplexing (OFDM) communications system such that low redundancy forward error correction in high data rate applications, comprising:
Dependencies are inferred from the claim text.