I. Introduction
The Long Term Evolution (LTE) is one of the systems beyond the third generation(3G). It has the ability to provide up to 100 Mbps in the downlink and 50 Mbps in the uplink [1]. As one of the key link adaptive technologies, adaptive modulation and coding (AMC) technology can improve the system throughput by adjusting coding rate to fit the instantaneous channel state information. Channel quality indicator (CQI) is derived by user equipment (UE) based on an unrestricted observation interval in time and frequency. The CQI index is restricted between 0 to 15 and each of them indicates a combination of modulation and coding schemes [2]. The accuracy of CQI plays an important role on the effectiveness of AMC schemes. However, CQI is not always reliable due to channel estimation error, CQI quantization error and CQI feedback delay.