Philadelphia's Drexel University is busy installing a thousand Draft 2.0 802.11n access points, a huge network project boasting a curious history and a cutthroat vendor evaluation process.

The private doctoral-research university of 21,000 students is swapping out Cisco 1200 Series “fat” 802.11g APs, installed in 2004, in favor of Aruba 802.11n-capable gear. One thousand 11n APs are going up, with dormitories to be completed by September and academic buildings to follow. Aruba controllers redundantly installed in three Drexel campus data centers will manage the APs, says Kenneth Blackney, Drexel’s associate VP of core technology.

In the past, the university has used leaky coax technology to extend signals throughout its dorms. Walls placed every 10 or 12 feet cause signals to attenuate, Blackney explains.

To compensate, Drexel has used coaxial cable as a long “antenna” that extends signal coverage. The outer conductor of leaky coax contains openings to let a controlled amount of RF signal leak out into the air, providing an alternative to deploying APs every few feet or springing for an expensive distributed antenna system (DAS).

“But we won’t use leaky coax with the Aruba installation, because our concern now is with dramatically increasing capacity, not coverage,” notes Blackney. “Instead, we’ll be installing about seven times as many APs as we have today.”

In addition to Aruba, final supplier contenders at Drexel were Cisco and Meru Networks.

“The real problem for Cisco at Drexel was that we use only standard POE [Power over Ethernet],” says Blackney.

Cisco has said that its Aironet 1250 802.11n solution requires about 18 Watts of power to run its dual radios (one in the 2.4GHz band and the other in the 5GHz band), while standard 802.3af POE devices supply just 15.4 Watts. To get the required power, Drexel would have had to use an alternative power source.

Cisco does supply the extra juice in some of its own switches, which comply with early versions of the emerging 802.3at 30-Watt power standard. However, “we’re sticking to one unratified standard at a time,” Blackney says, referencing the still pre-standard status of 802.11n products currently on the market.

Initially, the vendor’s ability to minimize co-channel interference was the university’s primary criterion - until Drexel decided to deploy 11n in the 5GHz bands only. “We’re an urban campus with lots of people around our periphery. The 2.4GHz spectrum is very crowded and noisy,” Blackney explains.

Joanie Wexler is an independent networking technology writer/editor in Silicon Valley.