Introduction to Mediumband Wireless Communication

The multipath is unavoidable in radio frequency (RF) wireless communication, and affects almost every element of the communication systems. The impact of multipath on the received signal depends on whether the delay spread (i.e., spread of time delays associated with different multipath components) is large or small relative to the symbol period of the wireless communication system. In narrowband channels, the symbol period is set such that the delay spread is about one tenth (or less) of it. In broadband channels, it is set such that the delay spread is many times greater than the symbol period. In between these two extremes, there appears to exist an important, yet overlooked, class of channels whose delay spread is neither small nor large enough for them to fall into these two basic channel classes. In this paper, we study the effect of multipath on channels that fall in the transitional region between narrowband and broadband referred henceforth as "mediumband". This paper shows that mediumband channels possess a distinct channel model, and pose both challenges and opportunities for reliable wireless communication. For instance, mediumband channels enable signalling at a significantly higher rate than that of narrowband channels, but on the flip side, as the degree of mediumband-ness increases, the quality of the channel deteriorates rapidly due to the excessive inter-symbol-interference (ISI). However, mediumband channels have an inherent ability to avoid deep fading, and if designed properly, mediumband wireless communication, which refers to wireless communication through mediumband channels, could be made to be significantly more reliable too.