Energy-Efficient Flexible Inter-Frequency Scanning Mechanism for Enhanced Small Cell Discovery

Heterogeneous Network deployments are one of the key enablers in providing ubiquitous coverage and capacity enhancements for satisfying high data rate and Quality of Service requirements for LTE-Advanced networks. In this paper we propose an energy efficient small cell discovery mechanism for heterogeneous networks by means of flexible inter-frequency scanning. We also propose the concept of threshold speed for inter-frequency scanning, above which mobile terminals should not search for or connect to inter-frequency small cells. Above threshold speed, the small cell connection opportunities become so short that they offer very limited benefit. The scheme is evaluated using extensive simulations conducted on HetNet scenario specified in 3GPP LTE-A system settings. Shortcomings of the currently standardized mechanism are analyzed and advantages of the proposed scheme are presented. Numerical analysis is done based on utilization of available offloading opportunities as well as savings in terminal battery power consumption. The results show that with the flexible scheme, significant power savings can be achieved with acceptable tradeoffs in offloading.