60 GHz Spectrum


Around 60GHz, about 7GHz of unchannelized frequency spectrum is available for license-free wireless communication applications. It is ideal for applications that demand ultra high speed data rates over short ranges. Products, based on compound semiconductors like GaAs and InP, exits in the market to operate in this range but they are power hungry and expensive. Because of expensive and bulky nature they not are suitable for consumer applications.Though this spectrum was available quite from some time, it was not exploited because of the challenges associated with their design and cost. Thanks to the recent developments in CMOS technology that made it possible to realize circuits for 60GHz applications. Now it is gaining attention from both industry and academia. According to ABI Research’s forecast, nearly two million 60 GHz chipset shipments takes place in 2015.

In free space the wavelength (\lambda_o) of a signal at 60GHz is 5mm. Hence 60GHz signals is also called by millimeter wave(mmWave)s. But in a dielectric the wavelength ( \lambda ) is dependent on relative permittivity \epsilon_r of the material and given by \lambda=\frac{\lambda_o}{\sqrt{\epsilon_r}}. Relative permittivity of SiO_2 is \epsilon_r = 4. Hence in silicon integrated circuits, the wavelength of 60GHz signal is 2.5mm instead of 5mm.

The availability of frequency spectrum for license free operation around 60GHz varies from region to region. Here is a breif summary of it.

Country/Region Frequency(GHz) Tx.Power(dBm)
USA 57-64 40dBm EIRP
Canada 57-64 40dBm EIRP
Korea 57-64
Japan 59-66 10dBm/57dBm EIRP
Australia 59.3-62.9
Europe 57-64 40dBm EIRP

Some interesting properties of 60GHz spectrum are

  • Signal in 60GHz band are high absorbed by Oxygen molecules : So it limits the link distance to small distances, which help in established wireless networks in dense environments.
  • Worldwide availability, acceptance and License-free operation
  • High allowable transmit power for improving the range and good signal strength.

Chip makers

  • Wi-Fi chip makers Intel, Broadcom and Atheros have voiced a desire tomake WiGig an extension of Wi-Fi, allowing users to take advantage of multi-gigabit speeds while near to a device or access point and falling back to conventional Wi-Fi rates when they move beyond the range of the 60GHz signal. With Wi-Fi already widely adopted around the world, being combined with that standard could give WiGig an easy path into networked products and users’ homes
  • Wilocity : Developing 60 GHz multi-gigabit wireless chipsets for both the mobile computing and peripheral markets
  • SiBEAM : SiBEAM is the first to build 60GHz chipsets using standard CMOS technology. The first applications for the company’s innovative technology are based on the WirelessHD™ specification for home multimedia content delivery and A/V connectivity.

Standards/Specifications

  • WiGig : Wireless Gigabit Alliance
  • WirelessHD : Specification for home multimedia, content delivery and A/V connectivity.WirelessHD was designed for video streaming between two devices, while WiGig is oriented more towards data networking.
  • IEEE 802.15.3c WPAN : Alternative Millimeter Wave(mmWave) based PHY layer standard for the existing 802.15.3 WPAN. The mmWave WPAN operates in 57-64 GHz band and supports high data rate at least 1 Gbps applications such as high speed internet access, streaming content download. An option for very high data rates(>2 Gbps) is provided for simultaneous time dependent applications such as real time multiple HDTV video stream and wireless data transfers.
  • IEEE 802.11AD task group is looking into modifications of IEEE 802.11 PHY & MAC standards to enable operation in 57-66GHz range.

Research

Applications

  • Wireless Personal Area Networks
  • Gigabit Wireless Local Area Networks(WLAN) : Capable of transmitting few gigabits of data per second over short distances
  • Wireless HDMI : Offer advantages to bandwidth-hungry applications such as high-definition video and high-capacity data storage
  • Point-to-Point 60-GHz Links / Wireless back-haul systems for 4G and video surveillance.
  • Imaging radar for military applications.
  • Vehicle radar system operating at a frequency of 60.5 GHz in Japan

Publications/References

  1. B. Razavi, “A 60-GHz CMOS receiver front end,” IEEE Jr. Solid-State Circuits, vol. 41, no. 1, pp. 17–22, Jan. 2006.
  2. Design considerations for 60 GHz CMOS radios
    Chinh H. Doan, Sohrab Emami, David A. Sobel, Ali M. Niknejad, and Robert W. Brodersen, Berkeley Wireless Research Center
  3. Millimeter-wave CMOS Design
    Chinh H. Doan, Sohrab Emami, Ali M. Niknejad, and Robert W. Brodersen, IEEE Jr. Solid-State Circuits, Vol. 40, No. 1, pp. 144–155, Jan. 2005.
  4. Gadgets Gab at 60 GHz : Razavi

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