Two solutions in one: smart antennas address siting, interference
The problems wireless carriers encounter with regard to tower siting and network interference could largely be things of the past with the implementation of “smart antenna” technology developed at Virginia Tech’s Mobile and Portable Radio Research Group (MPRG).
MPRG founder Ted Rappaport, a professor of electrical engineering at the university, said smart antenna technology is being tested by more than 12 companies. “Smart antennas are sort of in their infancy,” said Rappaport, who also is chairman of Wireless Valley Communications Inc. (see box, p. 2).
Smart antennas are designed to reduce the number of antennas needed to build out coverage of an area, known as the “range enhancement” function, and to increase the capacity of networks by reducing interference within the networks, which is called the “interference mitigation” function, Rappaport said.
…Fewer Cell Sites, Less Interference
By enhancing their antennas range, carriers are less likely to be forced to ask for approval of cell sites in residential areas. They also could need fewer cell sites altogether. “It removes the burden of frequency planning and makes site location less critical,” Rappaport said.
A federal court ruling last month allowing a Virginia city to deny tower siting proposals by two wireless carriers appears to indicate that even with the Telecommunications Act of 1996 as the bottom line, wireless carriers can’t tell local areas where to construct towers (MPN, Sept. 14, p. 1). One of the affected carriers, PrimeCo Personal Communications LLP, is asking the 4th U.S. Circuit Court of Appeals to reconsider its ruling.
Decreasing the amount of interference over carriers’ networks will allow room for more wireless transmissions. “Interference is the largest capacity user in most urban cell systems,” Rappaport said.
He added, though, that interference mitigation is “more of a challenge” than range enhancement. Solving network interference involves engineering work along an entire system, while increasing range can be done at individual cell sites.
There are obstacles to widespread implementation of the technology, but not insurmountable ones. “It’s extremely expensive right now,” Rappaport said, explaining that the technology costs 10 to 20 times what traditional antennas cost. “As deployment becomes more widespread and carriers gain confidence, that price will come down,” he said.
A second obstacle also touches on carriers’ confidence, though it’s not a cost factor. Rappaport said that like other industries, the “engineering inertia” of the wireless industry protects established practices at the expense of different ones that could be better.
“It’s very hard to go to new technology gracefully,” he said. “Smart antennas are no exception. It will take a little while.” He added that widespread deployment of all or selected elements of smart antenna technology should occur in three to five years.