US military takes pot shot at 802.11a

High-tech executives in the US are battling to prevent the Department of Defense from imposing restrictions on the use of radio spectrum for Wi-Fi products.

Defense officials said this month that they are concerned that proposals to open up more radio spectrum to cater for the increasing popularity of wireless LAN applications may end up interfering with military radar.

Executives from Microsoft, Intel and Cisco Systems met last week with the Department of Defense to persuade it against pursuing such restrictions on radio spectrum for future Wi-Fi technology, which is seen as a beacon of light for the beleaguered technology and telecoms industries.

Military officials have said, however, that the technical restrictions they are seeking are necessary for national security as they claim that low powered emissions from a WLAN can jam up to 10 different types of radar, including ones for tracking storms, monitoring aircraft and guiding missiles or weapons.

Industry executives, however, have responded by noting that such restrictions could threaten the expansion of Wi-Fi based technology, which provides wireless Internet in airports, coffee shops, homes and offices. Any restriction to the technology would be a huge blow to the IT industry, they say. Intel, in particular, plans to integrate Wi-Fi technology into all of its processor chips and invest $150 million in companies developing Wi-Fi applications.

So far, the US Federal Communications Commission has not received any reports of civilian WLAN interfering with military equipment.

Until the intervention by the DOD, the US seemed on the way to opening up the parts of the 5GHZ radio frequency for use in 802.11a equipment, which is currently allowed in Europe. A number of US Senators were said to be preparing bills to expand the radio spectrum for wireless Internet.

The DOD position was presented earlier this month to a technical meeting of the World Administrative Radio Conference, the body responsible for international radio frequency allocations and standards, and will be debated and perhaps decided at the World Administrative Radio Conference in June.

However, agreement may be reached between industry and government over a potential technical solution called dynamic frequency selection, which industry executives say will give military uses the "right of way" within the radio spectrum anytime they are in close proximity to civilian wireless Internet devices. Such technology is already in use in Europe. © ElectricNews.Net

Until the intervention by the DOD, the US seemed on the way to opening up the parts of the 5GHZ radio frequency for use in 802.11a equipment, which is currently allowed in Europe.

The DOD is going to have to find a new frequency anyway, given this reality.

Well, not necessarily. In Europe, 802.11a shares the band with Hiper LAN/2, an ATM-like wireless media, and the authority requires the use of Dynamic Frequency Selection and Transmit Power Control with that protocol. This makes the consumer appliance frequency- and power-agile when it detects interference, and is consistent with the Part-15 philosophy of "may not cause / must accept" w/r/t RF interference.

The part of the band which is shared with Europe (and Japan) is the lower-power sub-band (limited to 50mW for the part shared with Japan, and 250mW for the rest). Where the DOD might run into trouble is with the US-only part of the band, where the limit is the Part-15 standard one watt output, or 4W EIRP.

(source)

Obviously, DFS and TPC will need to be implemented in 802.11a equipment offered for sale in Europe, and it should be done here too, although it's not (yet) required by FCC. If DOD actually suffers QRM, however, something will have to be done.

Meanwhile, the old 802.11b band remains wide-open, with Linksys announcing a wireless amplifier (I assume it's awaiting FCC approval).

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