Harmonizing global 802.11a spectrum, Part 1

Decisions at the World Radiocommunication Conference, to be held June 9 – July 4 in Geneva, Switzerland, could yield a common set of global rules for running 54M-bit/sec 802.11a wireless LANs in the 5-GHz frequency range.

I sat down with Intel’s Jayne Stancavage, a member of the Wi-Fi Alliance board of directors, to discuss the 5-GHz spectrum issues currently on the table. I’ll share our conversation with you here in the first of a two-part Q&A series.

Wexler: What is the primary spectrum issue surrounding 802.11a?

Stancavage: Regulation for use of the 5-GHz band is not very harmonized among countries.

Wexler: What do you mean by “harmonized?”

Stancavage: Different portions of the spectrum are approved for wireless LAN use in different countries. For example, the U.S. and Canada currently allow Wi-Fi to operate in both the 5.15-to-5.35-GHz band and the 5.725-to-5.825-GHz band. Europe allows wireless LANs to operate in these bands and also in the 5.47-to-5.725-GHz band. Japan allows usage in a different spectrum.

Wexler: Why is it important to Wi-Fi customers to have consistent spectra assigned to 802.11a networks globally?

Stancavage: Having common frequencies and spectrum-usage restrictions would free customers from having to purchase different versions of products for use in different countries. In addition, because vendors currently must build products to separate sets of specs depending on geography, it’s hard for them to achieve economies of scale, which they could ultimately pass to their customers.

Wexler: What would the U.S. like to see happen?

Stancavage: The Wi-Fi Alliance petitioned the FCC in January 2002 to open the mid-band of 5.47 to 5.725-GHz for Wi-Fi use in the U.S. to match Europe’s frequency allocation for 802.11a. The additional spectrum would provide an extra 255 MHz of capacity for 802.11a products, enabling more wireless LAN channels and reducing the potential for interference.

Wexler: Why hasn’t the mid-band been in use to date in the U.S. for wireless LANs?

Stancavage: Initially, the U.S. military was concerned about potential interference issues. However, industry and government have now arrived at a compromise that would both protect military radars and allow Wi-Fi use in the mid-band. 

Wexler: What was the FCC’s response to your petition?

Stancavage: The FCC this month issued a Notice of Proposed Rulemaking to move forward with 802.11a use in the mid-band. However, there are operating restrictions that relate to power levels and dynamic frequency selection, also called “DFS,” which pertains to radar signal strength.

Next time: More technical details and the relevance of the emerging 802.11h standard.