CQI table design to support 256 QAM in small cell environment

The mobile data traffic is expected to grow beyond 1000 times by 2020 compared with it in 2010. In order to support 1000 times of capacity increase, improving spectrum efficiency is one of the important approaches. Meanwhile, in Long Term Evolution (LTE)-Advanced, small cell and hotspot are important scenarios for future network deployment to increase the capacity from the network density domain. Under such environment, the probability of high Signal to Interference plus Noise Ratio (SINR) region becomes larger which brings the possibility of introducing higher order modulation, i.e., 256 Quadrature Amplitude Modulation(QAM) to improve the spectrum efficiency. Channel quality indicator (CQI) table design is a key issue to support 256 QAM. In this paper, we investigate the feasibility of 256 QAM by SINR geometry and propose two methods on CQI table design to support the 256 QAM transmission. Simulation results show proposed methods can improve average user equipment (UE) throughput and cell center UE throughput with almost no loss on cell edge UE throughput.