A Survey of Dense Multipath and Its Impact on Wireless Systems

In recent years wireless propagation channel research has paid considerable attention to dense multipath, which is an indispensable part of propagation channels and may significantly contribute to the received power in variety of environments and frequency bands. Mathematical representation of dense multipath is different from that of specular components (SCs) due to its distinct propagation mechanism and impact on system performance. Therefore, accurate understanding and modeling of dense multipath together with SCs are important for parametric channel estimation and for reliable simulation in wireless applications. This paper first presents a systematic survey of studies of dense multipath in terms of different representations, channel modeling approaches and estimation methods. Thereafter, a comprehensive review of the characteristics and impact of dense multipath on performance of communication, localization and sensing systems is provided. Finally, open research topics are discussed.