Device power saving mechanisms for low cost MTC over LTE networks

3GPP has started to investigate feasibility of a low cost machine type communication (LC-MTC) terminal class in LTE networks in Release 12 aiming to be competitive with that of GSM/GPRS terminals targeting the same low-end MTC market with improved coverage. LC-MTC devices are expected to have limited power source. Since LTE technology is relatively more power hungry compared to GSM/GPRS, device power efficiency is one of the crucial requirements for LC-MTC over LTE networks. In this paper, we focus on exploring mechanisms to reduce power consumption for LC-MTC in LTE networks. Most of the current LTE power saving mechanisms are designed and optimized for human-to-human (H2H) communications which are not attractive for LC-MTC as traffic characteristics and service requirements for LC-MTC are expected to be largely different than those of H2H Communications. LC-MTC usually has very infrequent and small traffic burst mostly in UL. Therefore, one possible solution to maximize the power saving is to maximize the time with LTE radio turned off in between the traffic bursts. In this paper, we analyze the impact of turning off LTE radio without moving LC-MTC into Radio Resource Control (RRC) Idle and reducing the RRC Connected tail time (i.e., RRC Inactivity Timer). Our results show that turning LTE radio off after data transmission can achieve upto 95.28% reduction in power consumption compared to that in case of moving device to RRC Idle. Reducing RRC Connected tail time further improves the device power saving.