Advanced Satellite Technologies Offer True Path Diversity for 9-1-1 Networks

According to the National Emergency Number Association, an estimated 240 million calls are made to 9-1-1 in the US each year. For basic 9-1-1 service that means that when the three-digit number is dialed, a call dispatcher in the local Public Safety Answering Point (PSAP), or 9-1-1 call center, answers the call. The emergency and its location are communicated by voice (or TTY) between the caller and the dispatcher.

When these PSAPs are distributed across a large geographic area, for example, a county or state, the 9-1-1 network operates much like any other wide area network (WAN)—and is subject to many of the same problems, including disrupted cable lines and infrastructure. Because citizens need to be able to call for help in an emergency, solving the issue of outages is the ultimate challenge for governments operating 9-1-1 networks.

Keeping it Local

Often, agencies believe, “If our T1’s go down, we can use a cellular network as a backup.” What they may not realize is that while the signal to the tower may be wireless, there’s a potentially vulnerable terrestrial line from that tower to the telephone company’s Central Office. If that path becomes compromised, thousands may be left without a way to reach emergency services like police, firefighters, and EMTs.

Hughes SPACEWAY 3 satellite technology can reduce the risk of 9-1-1 outages by adding alternate network path connectivity, should a terrestrial network path ever become disrupted.

“With a single hop over the satellite, we can effectively back up those links and enable 9-1-1 networks to get back online in fractions of a second,” explained Paul Rabenhorst, director, Solutions Consulting at Hughes. “In today’s world, if the PSAP is running on a T1 and it goes down, they reroute the call to another PSAP. That’s not ideal, because you want to be connected to the local 9-1-1 answering point. With satellite as a backup, you’re always connecting to your local 9-1-1 PSAP. That’s what the satellite does.”

For advanced NextGen 9-1-1 (NG9-1-1) systems, which use Internet protocols to transmit voice, text, and video communications, SPACEWAY 3 satellite technology is a natural solution.

Power on the Spot

While terrestrial lines are vulnerable to cuts and power outages, traditional satellite systems can lose connectivity or experience signal weakening when there is too much moisture in the sky, known as rain fade. The “power pool” capability in SPACEWAY 3 enables Hughes to push more power to one or more of the satellite’s spot beams in order to strengthen the signal and compensate for weather conditions in those beams.

“The individual spot beams make that possible. We can pinpoint power to areas that need more attention. You can’t do that with a traditional satellite,” Rabenhorst said. This capability is key during weather events, such as hurricanes or blizzards, when emergency services are especially critical.

“Every 9-1-1 network is different. Our system is flexible enough that we can make it work with whatever we encounter in the 9-1-1 world,” he said.

Looking Beyond Failure in TexArkana

In the northeast corner of Texas, an area that includes TexArkana, the Ark-Tex Council of Governments (ATCOG) recently worked with Hughes to complete a series of tests designed to validate incorporating Hughes SPACEWAY 3 into their network to support the failover process and operational continuity.

To test the Hughes solution, several scenarios were created. One involved simulating an outage while a call was coming in to the network. Engineers “failed” both the primary and secondary paths, forcing the call to be carried over the satellite. Once the call was connected to the host and PSAP, testers allowed it to be transferred to a 10-digit number, simulating connections with the fire or police departments. In all cases, the calls were completed without interruption. The team also validated reactivating the primary paths.

Successfully Delivering True Path Diversity

“There was skepticism initially about going from a T1 to a satellite system without dropping the call. But the call never dropped. A traditional Ku-band satellite or one without a processor like SPACEWAY 3 would likely have dropped the call,” Rabenhorst said.

“For this type of true continuity, the satellite system has to be smart enough to do sophisticated traffic processing, especially in 9-1-1 networks that have more than one host site. To achieve the same level of capability with a more traditional satellite network would require a lot more equipment and be costlier to implement,” he added.

With the testing a success, Hughes services are now enabled to support 11 PSAPS and one of the hosts within the Ark-Tex 9-1-1 network, achieving true path diversity for the system.

“We understand that network challenges occur and also that there isn’t a particular method that is THE single solution. As a result, we’re setting up a diverse satellite network to provide additional redundancy to ATCOG’s regional 9-1-1 system for the safety of our citizens. A network solution using site-to-site satellite communications complements our primary network and provides an alternate communication path should issues arise,” said Mary Beth Rudel, Public Safety Manager for Ark-Tex.