Distributed Time Synchronization in Ultradense Networks

To fulfill a higher data rate requirement in fifth-generation (5G) systems, mobile network operators are steering the access architecture toward ultradense network (UDN) deployments. However, the coexisting small cells and macrocells in UDN require highly accurate timing synchronization among the base stations. Traditional master–slave-based time synchronization techniques are not well suited in several new deployment scenarios of 5G like dense urban, urban canyon, etc., which do not easily access the global positioning system (GPS). Moreover, a good back-haul requirement and high signaling overhead limit the applicability of existing techniques in small cell deployment scenarios. Despite a large amount of work done in the area, an efficient timing synchronization technique for dense networks is not well addressed, which this work aims to investigate. By applying an efficient approach for collecting information from an enlarged neighborhood at a minimal signaling cost in our modified timing update process, we provide a low-complexity and faster GPS-independent timing synchronization solution for a dense network. Numerical investigations evaluate the impact of the graph topology and nodes number on the network synchronization speed. Finally, we prove that the proposed algorithm achieves asymptotic convergence with probability one.