Free-space optics restores communications after Sept. 11

By CAROLYN MATHAS

Within a few blocks of Sept. 11's ground zero, on and near Centre Street, sit eight buildings of the Manhattan Courthouse system, a division of the New York state Unified Court System. The Sept. 11 attacks severely damaged segments of the court's communications system. To reconnect the Manhattan buildings to each other and to facilities located throughout the state, telecommunications specialists at the court system turned to an emerging optical communications technology: free-space optics.

Within the Centre Street vicinity are eight of nine lower Manhattan court buildings. The ninth facility, the New York state Court of Claims was unfortunately housed in 5 World Trade Center. Although the court's three judges and staff were successfully evacuated on Sept. 11, three court officers involved with the emergency operations were lost in the building's collapse.

According to Sheng Guo, chief technical officer for the Manhattan Court system, "Data communications were virtually destroyed as a result of the attacks. We had fiber coming down from Albany, and although the optical-fiber connection was still live, local connections were down. All T1 links from the main fiber feed were vanished. Our carrier's lines were down. In effect, all data and voice communications for the court system in Manhattan were shut down."

Even before the tragic events of Sept. 11, Guo began researching an alternative to its existing network and its inherent response time and bottleneck problems. Although a viable alternative would be to create a private fiber-optic network, two buildings in the Manhattan system were still without fiber-optic cable. These buildings, located next to the African-American burial grounds, a historical landmark, were subject to a prohibition against the laying of fiber until an archeologist and anthropologist could ensure no human remains were disturbed. Thus, within the CourtNet system, a combination of fiber and wireless technology served about 2,500 people in courtrooms, chambers, and offices prior to the attacks.

When he called the company on Sept. 15, a Saturday, Guo was referred to an after-hours emergency number. Ken Ito, senior product manager for Canon Broadcast & Communications, returned Guo's call, and a marathon weekend of locating equipment, training, and installation began. "Because it was a Saturday, I couldn't go through standard procedures-cut a purchase order, obtain the necessary approvals, etc. I told Ken, "Just trust my word, and he did," says Guo.

"There were several logistics problems," explains Ito. "I checked on the availability of equipment at the warehouse, and fortunately it was in stock. We agreed that Sunday morning I would open the warehouse and have our staff available to train the court's installation crew. Sheng and I contacted our respective staffs and on Sunday provided approximately an hour of training to three court engineers. Everyone involved made tremendous efforts to reach New Jersey on Sunday morning, since the city was still locked down."

According to Ito, each Canonbeam system could transmit up to 622 Mbits/sec in a straight-line distance of up to 2 km. The equipment featured fast setup and auto-tracking alignment technology and supported SNMP.

The high bandwidth provided by Canonbeam allowed the courts to effectively implement voice over IP (VoIP) throughout the CourtNet system at a time when traditional phone lines and cellular service were unavailable or undependable.

Using two groups of three or four installers on each building, installation began almost immediately. Questions throughout the installation process were handled over intermittently working cell phones. By the evening of Sept. 17, critical functions were re stored to the court system.

"We had no direct experience with free-space optics, reports Guo. "We were taking a risk, but an emergency forced us to do so. Under normal conditions, we may have come to the conclusion we couldn't afford this technology at that particular time. How ever, when court communications couldn't function, all of a sudden free-space optics was a bargain. There was nothing to lose since nothing was working."

By early October, the court's data network at its 123 Williams Street location was still not working. Guo says they went onto the building's rooftop, established line of sight, and purchased and installed another free-space system. Shortly thereafter, they also moved forward with a third system at 71 Thomas Street.

Currently, all systems are up and running and provide Fast Ethernet connections between the buildings. Providing additional capacity, up to OC-12, will simply involve trading out interface cards.

"Free-space optics is often perceived as being very new," says Ito. "It's thought to be more complicated than it actually is. The technology is very simple, and the way equipment is produced today, auto-tracking features are built-in and alignment is performed by the equipment."

Ito says system vendors such as Canon Broadcast & Communications have discussed the immediate disaster recovery benefits of free-space optical technology for quite some time. Although Ito says he was not expecting a call from the court system, the results highlight the technology's potential.