Transmission method of wireless signal and transmitter using the same

1. A transmission method of a wireless signal, comprising:

a. generating a plurality of orthogonal frequency division multiplexing (OFDM) symbols according to a data signal, wherein the OFDM symbols are carried by a plurality of subcarriers;

b. generating a scrambling pattern comprising a plurality of scrambling symbols respectively corresponding to the subcarriers in the frequency domain, wherein the scrambling symbols corresponding to two contiguous subcarriers are correlated; and

c. utilizing the scrambling symbols to encode the OFDM symbols carried by the corresponding subcarriers.

2. The transmission method of a wireless signal according to claim 1 , wherein the scrambling symbols all have an equivalent unit gain.

3. The transmission method of a wireless signal according to claim 1 , wherein the OFDM symbols comprise a plurality of data symbols and a plurality of pilot symbols, and the frequency difference between two contiguous pilot symbols in the frequency domain is smaller than a coherent bandwidth of the scrambling pattern.

4. The transmission method of a wireless signal according to claim 1 , wherein the step b comprises:

b1. generating a group of random numbers ranging from 0˜2π;

b2. enabling the random numbers to be uniformly distributed corresponding to the subcarriers; and

b3. linearly interpolating and low-pass filtering the uniformly distributed random numbers to generate the scrambling pattern.

5. The transmission method of a wireless signal according to claim 1 , wherein the step b comprises:

b4. generating a group of time domain signals with a delay spread;

b5. taking Fourier-transform on the group of time domain signals to obtain a group of frequency domain signals; and

b6. scaling the group of frequency domain signals to generate the scrambling pattern.

6. The transmission method of a wireless signal according to claim 5 , wherein in the step b5, the method further fine-tunes the group of time domain signals according to a Doppler frequency.

7. The transmission method of a wireless signal according to claim 6 , wherein the OFDM symbols comprise a plurality of data symbols and a plurality of pilot symbols, the frequency difference between two contiguous pilot symbols in the frequency domain is smaller than the coherent bandwidth of the scrambling pattern in a frequency dimension, and the time difference between two contiguous pilot symbols in the time domain is smaller than a coherent time of the scrambling pattern in a time dimension.

8. The transmission method of a wireless signal according to claim 1 , wherein the wireless signal is transmitted through a single frequency network (SFN).

9. The transmission method of a wireless signal according to claim 1 , wherein the method channel-encodes the data signal to generate the OFDM symbols.

10. The transmission method of a wireless signal according to claim 1 , wherein the method time-interleaves the data signal to generate the OFDM symbols.

11. The transmission method of a wireless signal according to claim 1 , wherein the scrambling symbols of the scrambling pattern are not identical.

12. A transmitter of a wireless signal, comprising:

an OFDM multiplexer for generating a plurality of OFDM symbols according to a data signal, wherein the OFDM symbols are carried by a plurality of subcarriers; and

a correlated scrambler for generating a scrambling pattern; the scrambling pattern comprising a plurality of scrambling symbols respectively corresponding to the subcarriers;

wherein the scrambling symbols corresponding to two contiguous subcarriers are correlated; and

wherein a plurality of scrambling symbols of the scrambling pattern are utilized to encode the OFDM symbols carried by the corresponding subcarriers.

13. The transmitter of a wireless signal according to claim 12 , wherein the scrambling symbols all have an equivalent unit gain.

14. The transmitter of a wireless signal according to claim 12 , wherein the OFDM symbols comprises a plurality of data symbols and a plurality of pilot symbols, and the frequency difference between two contiguous pilot symbols in the frequency domain is smaller than a coherent bandwidth of the scrambling pattern.

15. The transmitter of a wireless signal according to claim 12 , wherein the correlated scrambler comprises:

a random number generator for generating a group of random numbers ranging from 0˜2π;

a zero-padding unit for enabling the random numbers to be uniformly distributed corresponding to the subcarriers;

a linear interpolator for linearly interpolating the uniformly distributed random numbers;

a low-pass filter for low-pass filtering the linearly interpolated random numbers to generate the scrambling pattern; and

a multiplier for utilizing the scrambling symbols to encode the OFDM symbols carried by the corresponding subcarriers.

16. The transmitter of a wireless signal according to claim 12 , wherein the correlated scrambler comprises:

a path generator for generating a group of time domain signals with a delay spread;

a Fourier transformer for taking Fourier-transform on the group of time domain signals to obtain a group of frequency domain signals;

a scaler for scaling the group of frequency domain signals to generate the scrambling pattern; and

a multiplier for utilizing the scrambling symbols to encode the OFDM symbols carried by the corresponding subcarriers.

17. The transmitter of a wireless signal according to claim 16 , wherein the correlated scrambler further comprises:

a Doppler frequency adjusting device coupled between the path generator and the Fourier transformer for fine-tuning the group of time domain signals according to a Doppler frequency.

18. The transmitter of a wireless signal according to claim 17 , wherein the OFDM symbols comprise a plurality of data symbols and a plurality of pilot symbols, a frequency difference between two contiguous pilot symbols in the frequency domain is smaller than a coherent bandwidth of the scrambling pattern in a frequency dimension, and a time difference between two contiguous pilot symbols in the time domain is smaller than a coherent time of the scrambling pattern in a time dimension.

19. The transmitter of a wireless signal according to claim 12 , wherein the wireless signal is transmitted through a single frequency network (SFN).

20. The transmitter of a wireless signal according to claim 12 , further comprising:

a channel encoder for channel-encoding the data signal.

21. The transmitter of a wireless signal according to claim 20 , further comprising:

a time interleaver coupled between the channel encoder and the OFDM multiplexer for time-interleaving the channel-encoded data signal.

22. The transmitter of a wireless signal according to claim 12 , wherein the scrambling symbols of the scrambling pattern are not identical.