At the MAC or data-link layer, IEEE 802.11ad is compatible with the other IEEE 802.11x standards. Yet is PHY characteristics set it apart—and complicate testing.
Much hope has been pinned on the 60-GHz band as a new home for many emerging communications applications. Currently, few devices and technologies use this band. In addition, it is only lightly regulated while allowing for rapid data-transfer rates compared to existing wireless options in the 2.4- and 5.0-GHz bands. It may therefore prove a solution to today’s lack of bandwidth for the many data-hungry emerging consumer applications, which is why it is the band where the IEEE 802.11ad standard resides. That standard provides very high throughput to 7 Gb/s over a short range using approximately 2 GHz of spectrum. In a four-page application note titled, “Solutions for 802.11ad PHY Layer Testing,” Agilent Technologies pinpoints some design challenges and explains how they can be overcome.
IEEE 802.11ad is a backwards-compatible extension to IEEE 802.11-2007. The new specification adds a media-access-control (MAC)/physical layer (PHY) to provide short-range, high-capacity, point-to-point links at 60 GHz. To support a range of price/performance points to 6.75 Gb/s, it mixes single-carrier and orthogonal-frequency-division-multiplexing (OFDM) modulation techniques. At the MAC or data-link layer, it is compatible with the other IEEE 802.11x standards. Yet its PHY characteristics set it apart—and complicate testing.
IEEE 802.11ad measurement obstacles include the creation and analysis of 60-GHz signals (a new measurement challenge for most designers) with 2-GHz modulation bandwidth. Because the 2-GHz modulation bandwidth is much greater than that of other wireless communications systems, it requires different measurement tools and techniques. Because some devices lack a metallic connection, designers also may not be able to connect the device to the test equipment.
Thanks to applications like short-range radar and military communications, tools for millimeter-wave circuit design and simulation, network analysis, signal analysis, and power measurement have been available for a number of years. Although IEEE 802.11ad applications require a much wider modulation bandwidth, they can still be served by existing solutions. Of course, such solutions must be flexible enough to adapt to the standard’s changing requirements. Agilent suggests its SystemVue Electronic System Level (ESL) design software and 60-GHz PHY test solution. The firm then goes on to detail the aspects of these products that make them well suited for IEEE 802.11ad testing, which includes their simulation and signal-generation and analysis capabilities. In doing so, it efficiently explains why IEEE 802.11ad presents test challenges and how those issues can be successfully addressed.
Agilent Technologies, Inc., 5301 Stevens Creek Blvd., Santa Clara, CA 95051; (408) 345-8886, www.agilent.com.