Energy efficiency analysis of hybrid-ARQ relay-assisted schemes in LTE-based systems

This work deals with the analysis of energy efficiency (EE) issues of hybrid automatic repeat request (HARQ) protocols such as Chase combining (CC) and incremental redundancy (IR), in a LTE baseband-based half-division duplex relay-assisted network. The EE performance is highly dependent on delay and circuitry power consumption, i.e., baseband and radio-frequency (RF) parts, and the effects of these components are investigated for amplify and forward (AF) and decode and forward (DF) protocols. Moreover, a realistic estimation of the baseband power consumption is provided. Our contributions in this paper can be summarized as follows: (1) an accurate estimation of power consumption of the main blocks of the LTE baseband is provided based on a real field-programmable gate array (FPGA) target and is integrated to a global energy consumption model (2) based on the previous power consumption evaluation; energy-efficiencies of DF protocol with HARQ-CC and HARQ-IR are investigated with various modulation orders; in addition, a quite insightful study of the energy efficiency-spectral efficiency trade-off is conducted, and (3) DF and AF protocols with HARQ are compared in terms of EE, and recommendations are suggested in order to jointly enhance the QoS and the energy efficiency of wireless systems.