CQI-MCS Mapping for Green LTE Downlink Transmission

Maximizing the data rate and spectral efficiency are the main targets in LTE cellular systems. However, any increase in data rate or spectral efficiency will result in an undesirable increase in energy consumption. Hence, both energy efficiency (EE) and spectral efficiency (SE) necessitate to be optimized. In this paper, a multi-objective optimization framework is formulated to prove the tradeoff between both EE and SE in LTE downlink transmission. A new mapping algorithm between channel quality indicator (CQI) and modulation and coding scheme (MCS) is proposed by using a multi-criteria decision making technique. The proposed CQI- MCS mapping algorithm will search for the most suitable MCS according to the reported CQI value by considering the tradeoff between SE and EE while keeping block error rate (BLER) below its threshold value. Simulation results have shown that the proposed mapping algorithm can provide an efficient compromise solution compared to the existing 3GPP-LTE mapping. Therefore, the proposed CQI-MCS mapping can optimize the EE and SE based on different mapping values depending on the operator preferences.