Method of calibrating power for MIMO-OFDM transmitter
Provided is a method of calibrating a power for a multiple input and multiple output-orthogonal frequency division multiplexing transmitter having a plurality of antennas via a measurement equipment, the method including: receiving a cyclic delay diversity (CDD) signal simultaneously output from the transmitter to obtain a starting point of a frame of a corresponding signal; performing a fast Fourier transform on a sample proceeded from the starting point by an extent of a maximum CDD delay; calculating a channel coefficient; calculating a channel impulse response and a power of the channel impulse response; converting CDD delay values of each antenna into values in units of samples by using a sampling rate in the channel impulse response; mapping a peak point position of the channel impulse response to each antenna using CDD delay sample values; and simultaneously performing a power calibration of each antenna based on each peak point power.
1. A method of calibrating power for a multiple input and multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) transmitter having a plurality of antennas via a measurement equipment coupled to the MIMO-OFDM transmitter, the method comprising:
receiving, via the measurement equipment, a cyclic delay diversity (CDD) signal which is cyclically delayed for a predetermined time period and simultaneously output from the MIMO-OFDM transmitter to obtain a starting point of a frame of a corresponding signal;
performing, via the measurement equipment, a fast Fourier transform (FFT) on a sample preceded by a maximum CDD delay from the starting point of the frame;
calculating, via the measurement equipment, a channel coefficient H(n) by using an FFT calculated training symbol Y(n) and an ideal training symbol X(n), wherein n=0, 1, 2, . . . ;
calculating, via the measurement equipment, a channel impulse response h(k) by performing an inverse fast Fourier transform (IFFT) on the channel coefficient H(n) and calculating a power p(k) of the channel impulse response, wherein k=0, 1, 2, . . . ;
converting, via the measurement equipment, CDD delay values of each antenna into CDD delay sample values by using a sampling rate in the channel impulse response;
mapping, via the measurement equipment, a peak point position of the channel impulse response to each antenna by using the CDD delay sample values; and
simultaneously performing, via the measurement equipment, a power calibration of each antenna based on each peak point power of the plurality of antennas.
2. The method of claim 1 , wherein the channel coefficient H(n) is obtained by
H
(
n
)
=
Y
(
n
)
X
(
n
)
,
n
=
0
,
1
,
2
,
⋯
,
FFT
size
-
1.
3. The method of claim 1 , wherein the channel impulse response h(k) and the power p(k) thereof are obtained by
h ( k )=IFFT{ H ( n )}, k= 0,1,2, . . . ,FFT size−1 and
P ( k )=real( h ( k ))*real( h ( k ))+imag( h ( k ))*imag( h ( k )), k= 0,1,2, . . . ,FFT size−1.
4. The method of claim 2 , wherein the channel impulse response h(k) and the power p(k) thereof are obtained by
h ( k )=IFFT{ H ( n )}, k= 0,1,2, . . . ,FFT size−1 and
P ( k )=real( h ( k ))*real( h ( k ))+imag( h ( k ))*imag( h ( k )), k= 0,1,2, . . . ,FFT size−1.