Idle Mode Measurements to Enable Fast Small Cell Access without Compromising Energy Efficiency

Offloading traffic to small cells is one of the key enablers in achieving high peak data rates in a heterogeneous cellular network deployment. In this paper, we introduce and evaluate a solution to significantly speed up the small cell access in LTE or NR based on UE performing additional small cell measurements in idle state. These additional measurements naturally have a cost as additional energy consumption in the UE, but enable much faster small cell setup when there is data. The conventional wisdom has been to minimize the amount of measurements in the idle state to keep the UE battery life as long as possible. However, our results show that by leveraging the substantially better energy efficiency of data transmission in a small cell, a net positive effect can be achieved in a typical scenario. The performance gains are compelling: We observe user perceived throughput up to 5-10 times higher, while still maintaining lower average UE energy consumption.