Borderless Mobility in 5G Outdoor Ultra-Dense Networks

This paper considers borderless 5G ultra-dense networks (UDNs). In particular, a novel scheduling algorithm is proposed that achieves a more uniform distribution of user-throughput than that of the state-of-the-art maximum-throughput (MT) schedulers. The proposed scheduling algorithm also takes the coherence time of the channel into account as well as the impact to the acquired channel state information. A novel radio frame structure that is appropriate for achieving a 1-ms round trip time latency is also proposed. Such a low latency allows one to employ multiuser as well as cooperative multiple input multiple output schemes for mobile users. An evaluation of matched-filter and zero-forcing precoding for mobile users in UDNs is included. The performance of the proposed 5G UDN concept is assessed using a system-level simulator. Extensive numerical results show that the proposed borderless scheduling concept achieves $\sim 77$ % higher median user-throughput than that of the MT scheduler at the cost of $\sim 17$ % lower area-throughput. Such results are obtained for a high density of mobile users at velocities of $\sim 50$ km/h.