Method for selecting optimal beam and apparatus for receiving digital broadcasting signal using the same

1. A method for selecting an optimal beam to improve digital broadcasting receiving performance, the method comprising the steps of:

a) calculating a mainpath Signal to Multipath signal and Noise Ratio (SMNR) based on a channel impulse response for a plurality of beams which are formed according to steering directions from output signals of antennas, wherein the output signal of each antenna has different phase shift according to location of antenna element;

b) selecting a predetermined number of beams having a high SMNR value by comparing the calculated SMNR value for respective beam;

c) calculating a mainpath Signal to Dominant Multipath signal Ratio (SDMR) based on a channel impulse response corresponding to the selected beam; and

d) selecting a beam output signal having the biggest SDMR value by comparing SDMR values calculated in selecting a predetermined number of beams.

2. The method as recited in claim 1 , wherein in the step a), a signal having the biggest amplitude in respective channel impulse response is determined as a mainpath signal, and the other signals are determined as multipath signals and noise ratio in SMNR.

3. The method as recited in claim 1 , wherein the predetermined number of beams is determined based on the number of beams adapted to the digital broadcasting receiving apparatus.

4. An apparatus for receiving a digital broadcasting signal based on an optimal beam selection method, comprising:

a plurality of Radio Frequency (RF) front-end means for changing a RF signal received from respective element of an array antenna into a digital signal of an Intermediate Frequency (IF) band;

a plurality of beam forming means for forming a plurality of beams according to steering directions based on the IF signal outputted from the RF front-end means;

a plurality of demodulating means for demodulating the beam output signal formed in the beam forming means to baseband signal on a symbol-by-symbol basis;

a plurality of correlating means for generating a channel impulse response by correlating the output signal of the demodulating means with a training signal;

a plurality of beam selecting means for selecting a signal having the least channel distortion among the output signals outputted from the demodulating means based on a mainpath Signal to Multipath signal and Noise Ratio (SMNR) and a mainpath Signal to Dominant Multipath signal Ratio (SDMR) for respective channel impulse response generated in the correlating means; and

an equalizing means for compensating a channel distortion in the output signal of the beam selecting means.

5. The apparatus as recited in claim 4 , the beam selecting means includes:

a first calculating means for calculating a mainpath Signal to Multipath signal and Noise Ratio (SMNR) based on a channel impulse response for a plurality of beams which are formed according to steering directions from output signals of antennas, wherein the output signal of each antenna has different phase shift according to location of antenna element;

a first selecting means for selecting a predetermined number of beams having a high SMNR value by comparing the calculated SMNR value for respective beam;

a second calculating means for calculating a mainpath Signal to Dominant Multipath signal Ratio (SDMR) based on a channel impulse response corresponding to the selected beam; and

a second selecting means for selecting a beam output signal having the largest SDMR value by comparing SDMR values calculated in selecting a predetermined number of beams.

6. The apparatus as recited in claim 5 , wherein a signal having the largest amplitude in respective channel impulse response is determined as a mainpath signal, and the other signals are determined as multipath signals and noise ratio in SMNR.

7. The apparatus as recited in claim 5 , wherein the predetermined number of beam is determined based on the number of beams adapted to the digital broadcasting receiving apparatus.