Improving the Energy Efficiency in a Single-Cell Cellular System by Adapting User Equipment LNA Stages and Base Station Transmit Power

In a receiver front-end, the noise figure (NF) decreases and the third order intermodulation interference increases with increasing the number of active low noise amplifier (LNA) stages. Thus, the number of active LNA stages of a receiver front-end should be adapted based on the interferer power on it such that the overall interference is less than a predefined threshold. In this paper, we propose orthogonal multiple access (OMA) and power-domain non-orthogonal multiple access (NOMA) based downlink cellular systems in which receiver frontends of the user equipment (UEs) consist of cascaded LNAs with adaptive stages. To improve energy efficiency (EE), we provide a methodology to adapt the number of active LNA stages of the UEs and control the BS transmit power levels for downlink transmissions. The EE of the proposed systems under the provided methodology is evaluated and compared with the EE of OMA and NOMA cellular systems with single stage LNA. We find that the EE of OMA and NOMA cellular systems can be improved significantly by adapting the number of active LNA stages of the receiver front-ends and the impact of adapting the active LNA stages in improving EE is more significant in a NOMA system than an OMA system.