Measurement method and system of channel quality indicator in space time transmit diversity system

The present invention provides a measurement method of a channel quality indicator in a space time transmit diversity system. The method comprises the steps of receiving the first data and the second data of a primary common pilot channel (P-CPICH), balancing, descrambling and de-spreading the balanced first data and second data to obtain the descrambled and de-spread first data and second data, and classifying and merging the descrambled and de-spread first data and second data according to a P-CPICH symbol pattern to generate the first merged data and the second merged data. When the first data and the second data are same, the first merged data is the sum of the descrambled and de-spread first data and second data, and the second merged data is zero; when the first data and the second data are different, the first merged data is zero, and the second merged data is the subtraction of the descrambled and de-spread first data and second data. A first signal to interference noise ratio (SINR) and a second SINR are generated according to the first merged data and the second merged data and are averaged to generate the SINR of the P-CPICH, the SINR of a high-speed physical downlink shared channel (HS-PDSCH) is generated according to the SINR of the P-CPICH, and the channel quality indicator is obtained according to the interval measurement of the SINR of the HS-PDSCH.