Issue Archive: August 2006

New technology: E9-1-1—To Migrate or Stagnate?

Author: Dennis Cleary

This article will compare the “traditional” 9-1-1 networks that exist today with new, very feasible, cost-effective networks that provide faster connection times and solid redundant designs that will support vital new public safety applications.

Voice over Internet Protocol (VoIP) is a technology that allows voice to be carried through a broadband connection. IP is seemingly taking over the telecommunication industry. IP will support future applications as technology advances.

Some examples of these new applications are:

• Regional and statewide Emergency Management and Homeland Security applications
• GIS applications
• Instant messaging, private e-mail
• PSAP-to-PSAP transfers
• Telematics
• Automatic Crash Notification (ACN)

The technology to accomplish improvements and to take advantage of future applications is here today. Many local, regional and statewide 9-1-1 systems are implementing these more advanced networks. The newer 9-1-1 networks are improving mission-critical response times by routing packet-based data through digital circuits to IP gateways. With the high number of calls connecting to 9-1-1 systems today, these new tools and technologies are a must for supporting the public we serve.

Improving Technology

A few statistics are noteworthy to support the need for improved networks and to highlight how much we have advanced in the 30 plus years our 9-1-1 systems have been in place. According to the Cellular Telephone Industry Association (CTIA), as of May 12, 2006, there were 213,654,767 wireless subscribers supported by nearly 14,000 new sites, which have been built each year for the past five years. About 225,000 wireless calls are made to PSAPs or other emergency centers throughout the country per day.

According to Citicorp’s estimates, there will be 250 million wireless subscribers in the U.S. by the year 2010. Speaking in general, from a network standpoint, our legacy 9-1-1 systems have not changed all that much since the implementation of the first 9-1-1 system in Haleyville, AL in 1968, more than 38 years ago.

Computers and handheld mobile communication devices did not exist when analog systems were implemented. Requests for help (via 9-1-1) to emergency service providers came from landline telephones. Things were much simpler back then. With the advent of telematics providers, ACN, cellular telephones, WiFi phones, two-way pagers and other communications technologies that are yet to come, analog networks have become obstacles in the path of progress.

The improvements made in new technologies regarding networking, equipment, self-healing fiber optic rings and improved software have been amazing over that last 15 years. Today, the LECs provide the switching, routing, database management and circuits. There is an alternative to the typical 9-1-1 network being provided by the LECs today. Town, city, county and state governments can now own, manage and operate their own using enhanced 9-1-1 systems that use newer, more reliable technology, and are often cost efficient.

Analog Networks

To help understand the technologies available today, let’s take a quick look at some terminology. It is important to understand an analog environment versus a digital environment. In an analog transmission system, signals propagate through the medium as continuously varying electromagnetic waves. These sines are amplified, including the noise.

In a digital system, signals propagate as discrete voltage pulses (that is, a positive voltage represents binary one and a negative voltage represents binary zero), which are measured in bits per second. No noise is amplified. A digital environment is a multi-layered architecture and comprises a set of protocol specifications for networks. The information is encoded as a series of bits, rather than a fluctuating analog signal. All information is transmitted in a binary-encoded form.

The typical PSAP throughout the U.S. is functioning behind analog networks using CAMA trunks. The LECs own and maintain the many selective routers in their central offices. These routers talk to their switches and receive information such as Automatic Number Identification (ANI). The selective router sends the call to the correct PSAP based on data loaded into the router. Both wireline and wireless calls typically come into the PSAP in an analog environment with ANI and an ALI record. Figure 1 is an illustration of this type of network in a wireless environment.

Consider that the LECs have many selective routers and the wireless carriers have to connect to each of them with redundancy. The need to consolidate these trunks is important for cost reduction and more efficient network management. Also, in most cases, the LECs are not operating in a totally digital environment. Frequently, there is no network redundancy in the outside facilities feeding the PSAPs.

IP Network

Some benefits of these type networks are:

• Speed of data through the network is drastically increased
• Call set up times are drastically reduced
• More data can be moved through the network (not limited to ALI and ANI)
• Video, imagery, e-mail and other forms of data
• Call transfers between PSAPs, not restricted by wire centers
• No LATA boundaries, a statewide network resulting in statewide communication between PSAPs
• Supports all current and future IP technologies
• Consolidation of circuits, reduced circuit costs
• Less to go wrong, fewer components make up the network
• Potential long term cost savings

This design is based on using two selective routers in different locations for redundancy. These routers will interconnect via SS7 links. All outgoing trunks are provisioned on DS1s. The PSAP is now in a digital environment for its facility using ISDN PRI connectivity. The secure, private, redundant IP network is facilitated by state-owned or co-op owned fiber optic segments in some states, thereby reducing circuit cost and providing a self healing ring. The wireless carriers only have to connect to the two independent tandem switches. This reduces their network size to a much more cost efficient network with less to go wrong and much easier to manage. With this scenario, the wireless carriers do not have to connect to each LEC in a given state.

IP is sweeping the telecommunications industry, impacting many current applications and promises to be the standard by which communications are based in the future. Internet Protocol is an opensystem protocol that is non-proprietary. The IP suite can be used in a LAN or WAN environment. IP is a network layer protocol used for communicating data over packet switched networks. A good description of IP states: IP is a network-layer (Layer 3) protocol that contains addressing information and some control information that enables packets to be routed.1 IP has two primary responsibilities: providing connectionless, best-effort delivery of datagrams or packets through an internet work; and providing fragmentation and reassembly of datagrams to support data links with different maximum- transmission unit sizes. There are 14 separate elements in an

IP packet.  Each field includes:

1. Version—Identifies the IP version currently being used. IPv4 uses 32-bit addresses. IPv6 is the proposed successor to IPv4 and it uses 128-bit addresses.
2. IHL—IP Header Length
3. Type of Service—Indicates how the upper layer protocols would like to handle the data and at what level of importance.
4. Total Length—Indicates the length in bits for the entire packet including the header and data.
5. Identification—This field is used as a defragmenter for the datagram.
6. Flags—Controls fragmentation with one flag spare.
7. Fragment Offset—Allows the destination IP process to properly reconstruct the original datagram.
8. Time to live—Datagrams can be discarded. This field counts time.
9. Protocol—This field tells which upper layer protocol receives incoming packets after processing is finished.
10. Header Checksum—Ensures IP header is correct.
11. Source address—Tells the sending node.
12. Destination address—Tells the receiving node.
13. Options—For additional support.
14. Data—Contains upper-layer information.

The most widely used version of IP today is Internet Protocol Version 4 (IPv4). IP Version 6 is beginning to be supported. IPv6 provides for much longer addresses and, therefore, the possibility of many more Internet users. IPv6 includes the capabilities of IPv4. Any server that can support IPv6 packets can also support IPv4 packets. IPv6 is commonly referred to as IPing.

Recent Standards

The scalability and compatibility of IP networks is the technology to adopt for mission-critical 9-1-1 networks, particularly when considering the 9-1-1 enforcement actions from the FCC with regard to Phase 1 and Phase 2 migration. Recent information released on June 6, 2006 by the National Emergency Number Association (NENA) states more than 75 percent of the population is now covered by Phase 2 wireless E9-1-1. Recent congressional legislation ensured state responsibility in regard to 9-1-1 funding and assists public safety in its efforts to pay for the cost of hardware, software upgrades and consulting fees.

NENA is currently working on standards for VoIP E9-1-1. The NENA VoIP/Packet Technical Committee has identified three elements in our migration to an E9-1-1 IP system. They are I1, I2 and I3. The detailed explanation for each step of this migration path can be found at www.nena.org.

Consulting firms across the country are earning their keep by authoring cost/feasibility analyses, Requests for Information, Requests for Proposals, studying the responses for recommendation and implementation/project management in support of the heightened interest in migrating to a Next Generation 9-1-1 program.

Several incidents around the country in the recent past have made national news. Complaints from people receiving unsatisfactory service from emergency services are on the rise. 9-1-1 calls are going unanswered, being misrouted and providing incorrect data to the call takers. With the ever increasing number of wireless 9-1-1 calls, VoIP calls and telematics, analog networks cannot continue to function reliably or provide the compatibility needed that future technologies will require.

Dennis Cleary, a telecommunications specialist in L. Robert Kimball & Associate’s Melbourne, FL office, has more than 30 years of experience in the telecommunications industry, focusing on design, implementation, maintenance and management of appropriate service levels. He can be reached at (321) 733-7756 or (321) 446-3687 ( cell).

References

Cisco Systems. Online. (June 2006) www.cisco.com/public/support/tac/documentation.html

 

Odom, W. (2004). CCNA INTRO: Self Study Exam Certification Guide.

National Emergency Number Association. Online. (June 2006). Short Description I1, I2, and I3. www.nena.org

 

Cisco Systems. Online. (June 2006) www.cisco.com/public/support/tac/documentation.html

 

Microsoft Computer Dictionary. Fifth Edition. (2002).

www.nena.org