Energy efficient relay selection scheme with DRX mechanism in 3GPP LTE network

As bandwidth scarcity problem is widely agreed, communication through high frequency band has been considered for future commercial cellular networks. However, according to its radio propagation property, out of service area will be increased. So, relay-based cooperative communication has been emerging as a promising solution. In relay-based cooperative communication, energy efficiency is crucial factor due to battery issue of relay stations. But, most of conventional relay selection schemes does not consider both energy efficiency and sleep operation of relay stations which can reduce power consumption. Thus, we construct Discrete Time Markov Chain (DTMC) model for the relay station which has DRX mechanism, and analyze that model. Also, we propose a novel energy efficiency metric called Relay Energy Efficiency (REE), and REE-based energy efficient relay selection scheme. Numerical results show that proposed relay selection scheme achieves higher energy efficiency than other conventional schemes.