Title: Revisiting Frequency Reuse towards Supporting Ultra-Reliable Ubiquitous-Rate Communication,
Abstract: One of the goals of 5G wireless systems stated by the NGMN alliance is to
provide moderate rates (50+ Mbps) everywhere and with very high reliability. We
term this service Ultra-Reliable Ubiquitous-Rate Communication (UR2C). This
paper investigates the role of frequency reuse in supporting UR2C in the
downlink. To this end, two frequency reuse schemes are considered:
user-specific frequency reuse (FRu) and BS-specific frequency reuse (FRb). For
a given unit frequency channel, FRu reduces the number of serving user
equipments (UEs), whereas FRb directly decreases the number of interfering base
stations (BSs). This increases the distance from the interfering BSs and the
signal-to-interference ratio (SIR) attains ultra-reliability, e.g. 99% SIR
coverage at a randomly picked UE. The ultra-reliability is, however, achieved
at the cost of the reduced frequency allocation, which may degrade overall
downlink rate. To fairly capture this reliability-rate tradeoff, we propose
ubiquitous rate defined as the maximum downlink rate whose required SIR can be
achieved with ultra-reliability. By using stochastic geometry, we derive
closed-form ubiquitous rate as well as the optimal frequency reuse rules for
UR2C.