MultiGigabit millimeter wave communication: System concepts and challenges

The millimeter wave band from 60-95 GHz offers large swathes of unlicensed and semi-unlicensed spectrum, which may well form the basis for the next revolution in wireless communication, in which wireless catches up with wires.With the rapid scaling of silicon processes, low-cost implementations for radio frequency front-ends are on the horizon. A key challenge now is to parlay these breakthroughs into innovative system concepts. We review three such concepts here.Millimeter wave MIMO: The small carrier wavelength enables spatial multiplexing in line-of-sight environments, potentially resulting in point-to-point outdoor wireless links at optical speeds (40 Gbps) using bandwidths of the order of 5 GHz. Directional multihop networking: Indoor Gigabit wireless links based on 60 GHz unlicensed spectrum are subject to disruption due to line-of-sight blockage by obstacles such as furniture and humans. We show that a multihop architecture with a small number of relays assures full network connectivity. All-digital multiGigabit baseband: Since high-speed analog-to- digital conversion (ADC) is costly and power-hungry, in order to design all-digital baseband processing that can be implemented inexpensively by riding Moore's law, we must be able to perform signal processing with sloppy ADC. We discuss Shannon-theoretic limits and signal processing challenges in this context.