ABSTRACT
In contrast to the scarcity of bandwidth typical at lower frequencies, large swathes of unlicensed spectrum are available worldwide in the 60 GHz band (including 7 GHz of spectrum from 57–64 GHz in the United States). Such “millimeter (mm) wave” frequencies have been used in cost-insensitive applications such as military radar and communication systems for decades, using expensively packaged radio frequency-integrated circuits (RFICs) implemented in low-volume compound semiconductor processes. However, intense commercial interest in the 60 GHz band has developed in recent years, because it is now becoming possible to realize 60 GHz radios using silicon radio frequency-integrated circuits (RFICs) in cost-effective packaging. The goal of this chapter is to provide a glimpse of potential applications and system design considerations for emerging 60 GHz wireless systems that capitalize on these hardware advances. We begin with a brief discussion on such applications, but devote most of the exposition to a discussion on the new design considerations relative to those in the cellular and WiFi networks that wireless designers are most familiar with. These design considerations arise from the order of magnitude smaller carrier wavelength at 60 GHz relative to these existing systems, which has significant implications for transceiver hardware, physical layer modeling and design, signal processing architectures, and network protocol design. For outdoor communication, another important feature of the 60 GHz band is its oxygen absorption, which leads to a propagation loss of about 16 dB/km on top of the loss due to free space propagation. Rain leads to further loss (e.g., about an additional 21 dB/km for heavy rain of 50 mm per hour).
