Mobility enhancement and performance evaluation for 5G Ultra dense Networks

Future wireless network will address the explosive increase demand of high-data-rate video services as well as massive-access machine type communication (MTC) requests, so that increasing number of small cells are conceived to be densely deployed in hot spots, resulting in an Ultra-dense Network (UDN). As a main issue for the future network, UDN is a step further towards a low-cost, self-configuring and self-optimizing network, while also leading to high-frequent measurement, intolerable handover failure (HOF), as well as huge power consumption in both the terminal and access network. Thus, mobility enhancement in ultra-dense scenario has become a critical problem for the next generation wireless systems. To solve this problem, the split of control plane and user plane (C/U) has become one of the most promising way, as it allows more flexibility and better service control schemes. Inspired by this, a set of macro assisted small cell enhancement schemes is proposed contributing to a novel Data-only Carrier (DoC) system in our previous work. In this paper, for improving the handover (HO) performance, new mobility-enhanced schemes are designed and analyzed in detail in DoC network, taking into consideration of mobility, flexibility and various typical handover scenarios. Simulations are conducted by a system-level platform to illustrate the fundamental relationship between key handover parameters and mobility performance. Numerical results show that the gain of system HOF rises by 53.6% via optimizing and reconfiguring the handover parameters in DoC network. In addition, the DoC network has an excellent performance gain in UDN with 82% HO improvement and 44.34% energy efficiency promotion compared with the current LTE network, which may be a promising mobility enhancement strategy for future 5G networks.