Digital Signals: How we got here, and where we could get to

This survey examines the bandwidth efficiency of wireless signals, beginning with a review of the Shannon capacity and of the important differences between signal to noise ratio (snr) and individual bit energy to noise density (IBEND = E_b/N₀). Recognizing that communication systems are successful only if they are profitable, value propositions that have been realized along the evolution of adopted wireless signals are reviewed. As the market now desires gigabit data rates while mobile, physical principles are used to extend this historical trend to evaluate options for implementation and their inherent costs so that coming value propositions can be fairly evaluated.