Adaptive channel quality feedback for LTE

In Long Term Evolution (LTE) networks, resource allocation and link adaptation rely on the channel quality indicator (CQI), which is a quantized representation of the signal interference plus noise ratio (SINR). Since CQI is measured by user equipment (UE) and sent to eNodeB via a feedback channel, in time varying channel, feedback delay should be compensated with prediction based on previous knowledge. In this work, several known prediction schemes are studied. Moreover, an adaptive CQI feedback scheme based on the sample autocovariance function is proposed. Simulation results show the proposed prediction scheme outperforms the other known prediction schemes in terms of overall prediction accuracy and system throughput. In addition, the performance is evaluated for systems both with and without hybrid automatic repeat request (HARQ), to investigate the influence of HARQ.