Method and Arrangement Relating to the Insertion of Pilot Tones in the Frequency Domain in SC-FDMA

A method of enhancing the efficiency of a transmission using Single Channel-Frequency Division Multiple Access (SC-FDMA), the method comprising the steps of:

• applying a Discrete Fourier Transformation (DFT) of a time signal providing N0 samples to produce a first signal;
• inserting N1 pilot tones into the first signal to produce a DFT signal having N0+N1 tones;
• interpolating the DFT signal to a predetermined size N, with N being a value greater than N0+N1, by inserting zero tones of the DFT signal to produce a modified frequency domain signal having N tones, wherein N=2m with m being an integer;
• applying Inversed Fast Fourier Transform (IFFT) on the modified frequency domain signal;
• and
• transmitting the modified signal.

A method of receiving, in a Single Channel-Frequency Division Multiple Access (SC-FDMA), the transmitted signal of claim 1 comprising:

• performing a channel estimation in the frequency domain using an N size Fast Fourier Transform (FFT) of the received signal;
• removing extra pilot tones or reserved tones that have been transmitted in the received signal;
• removing tones corresponding to the transmitted zero tones;
• reducing the FFT size from N to N0 tones;
• and
• recovering the original N0 samples in a time signal by an Inverse DFT operation.

An arrangement for processing a signal for transmission using Single Channel Frequency Division Multiple Access (SC-FDMA), the arrangement comprising:

• a symbol receiver configured to receive a sequence of symbols to provide a time signal;
• a processing arrangement configured to compute a Discrete Fourier Transformation (DFT) of the time signal to produce a time signal having N0 samples;
• a first arrangement configured to insert N1 pilot tones into the time signal to produce a DFT signal having N0+N1 tones;
• an interpolator configured to interpolate the DFT signal having N0+N1 tones to a predetermined size N, with N being a value that is greater than N0+N1, by inserting zero tones in the DFT signal to produce a modified frequency domain signal of N tones, wherein N=2m with m being an integer;
• a second arrangement configured to insert zero bins into a middle section of the DFT signal to produce a modified signal;
• a processing arrangement for applying Inversed Fast Fourier Transform (IFFT) on the modified signal;
• and
• a transmitter configured to transmit the modified signal.

A receiver for receiving a (SC-FDMA) modulated signal, the receiver comprising:

• a receiver portion configured to perform a channel estimation using an N size Fast Fourier Transform (FFT) of the received signal;
• a first processing arrangement configured to process the received signal in the frequency domain;
• a second processing arrangement configured to remove zero filled bins, and to reduce the FFT size from N to one of N0+N1 pilot tones, N0+N2 reverse tones, and N0+N1+N2 pilot tones and reverse tones;
• a third processing arrangement configured to remove the N1 pilot tones, or the N2 reverse tones, or the N1-N2 pilot tones and reverse tones, such that N0 tones remain;
• a fourth processing arrangement configured to recover an original time signal using an Inverse DFT (DFT) operation.