LTE — ‘What Is It and Why Should I Care?’
By Ron Haraseth
Editor’s note: How to be innovative and flexible in meeting mission-critical requirements for public safety in a standards-based technology world was a major point of discussion at the 2010 IWCE in Las Vegas this week. IWCE reportedly saw about 15% growth this year over last, and attendees and vendors alike expressed satisfaction with their experience. The keynote speaker on Wednesday morning, Abhi Ingle, vice president of Industry & Mobility Application Solutions for AT&T, said, “LTE is the path to interoperable convergent communications. … LTE has excellent propagation characteristics.” But what do public safety communication personnel really need to know about LTE? For more on this topic, we turn to long-time APCO member Ron Haraseth.
LTE — is it just another acronym in a business already flooded with acronyms? High tech has always been a tool for public safety, and it wasn’t too long ago that a simple two-way radio, telephone or the teletype was the height of technology. Modern information technology supporting public safety communications has expanded, becoming an essential pillar of support. Technology’s role in the various disciplines has incrementally increased the effectiveness of service delivery and, if implemented correctly, works silently and almost invisibly in the background. LTE is just another tool in our arsenal, but we shouldn’t take it for granted.
If you haven’t heard the term LTE, you will. It stands for long-term evolution — and the word evolution will certainly live up to its meaning. The latest generation of wireless phone technologies, LTE, is capable of becoming a significant convergence factor for the delivery of many services and applications in the mobile environment. Let’s examine where it fits in the evolutionary tree of information delivery.
Background
First, we need to define communications on a broad scale and how communications is used in a context specific to the requirements of distributing and managing the flow of information to support public safety missions. Voice has always been — and remains — the primary means of implementing communications. Although there are other more subtle physical forms of communications, voice is the platform that has propelled humanity to its current level of civilization. People, however, are visual thinkers by nature. Actions speak louder than words, but actions are too transient and complex to convey over time and distance. Thus, the ability to break down visual objects, physical actions and abstract thoughts into a code decipherable remotely by another individual over both distance and time has proved absolutely invaluable. Writing is essentially the recorded equivalent of voice. Voice still becomes the most direct and proactive means of conveying information because of the direct interaction with its inherent error correction — if you don’t get it, ask for a repeat or rewording. Although we have established real-time voice as king, recorded voice, writing and pictures all have a place in the accurate conveyance of information, particularly when time and distance become elements. All are key methods used to support public safety operations.
So voice is king, at least for instant communications, followed by textual representation of voice for delayed communications relay, and pictures (or graphic display) complete the parade. How have these three icons been used by public safety over the past century? What technologies do we have in place to support this exchange of information? Let’s jump forward — past smoke signals, teletype, telephone and wireless telegraph with which we are all familiar — to the modern era of two-way radio, cell phones and fax machines.
Two-way radio’s impact on public safety was most significant with the advent of FM mobile radios developed after World War II. It extended the distance by which we can exchange real-time voice information. Radio technology was quickly embraced during the ’50s with tube-based radios. The technology expanded with the introduction of solid state transistorized versions in the ’60s and ’70s. The ’80s saw the introduction of trunking and computer control of the radios. An occasional agency tied their radio system to the public switched telephone network (PSTN), but it was rare and a poor use of radio systems. There are significant differences in how we use each service, a fact that continues on through today. The basic leap — or evolution — was in the provision of real mobility supporting public safety missions. Landline voice, common telephone, was still tied to fixed locations with some minor exceptions.
In the late ’80s, cell phones became available. The first cell phones were mere mobile extensions of the capabilities of wire-based telephones. As the cost of cell phones decreased and coverage increased, more and more agencies issued cell phones to their mobile work forces, and personal use by public safety first responders grew. It’s now difficult to find an individual who does not carry a cell phone. A key element to remember here is that cell phones were entirely designed to equip the needs of the commercial mobile public with little, if any, consideration for requirements that might be specific to public safety.
It’s important not to equate cell phone use with classic two-way radio use. Although both provide voice capability, their dynamics of service are quite different. Two-way radio provides a one-to-many capability with a virtually unlimited “many,” as well as a direct mode that can be used without external support through some form of base station and associated fixed infrastructure. These elements are key to the future of public safety mobile communications. Cell phones require fixed base stations, cannot talk directly to each other and have a very limited one-to-many capability. While typical two-way radio calls are measured in seconds and intended for multiple listeners, cell phone calls are typically measured in minutes and are intended for only one listener.
Another simple difference: Two-way radio uses a single small resource (frequency or channel) for a call whether it’s connecting with one listener or a thousand listeners — one frequency/channel unit supporting anywhere from two to hundreds of units. Cell phone technology, on the other hand, is based on old fashioned land telephone concepts called circuit switched. Each connected party on a cell phone requires a frequency or channel resource (circuit). Two cell phones talking to each other connect through a base station (or typically, multiple base stations), each requiring its own frequency/channel — two frequency/channels units for two units to communicate. Even an iDen[1] push-to-talk phone operates this way. Each additional party to the initiated call uses a separate frequency/channel resource. Remember, cell phone usage is based as an outgrowth of regular land-based telephones in which private one-to-one calls were the goal. The total concurrent number of calls in any given cell coverage area is highly restricted by limited channel/frequency resources.
Why this frequency/channel lesson? The underlying technology for cell phones is changing. Modern cell phones have evolved into smart phones capable of data exchange, including text, video and graphics, but they operate using two transport subsystems, one for voice-based communications over the old landline premise and the second system is reserved for data. Modern cell phones are dual-mode devices. The data mode operates quite differently. With the advent of the Internet, Internet protocol (IP) and Internet packet concepts, the common element of transport for data is no longer the single frequency/channel. Many of the barriers and limitations of the types of intelligence that can be transmitted over the airwaves are removed. Using timing, phasing and other techniques, each intelligent information stream is essentially pulled apart into tiny components and crammed onto a super wide radio frequency channel along with many other concurrent information streams. At the other end, all of these different intelligence streams are reconstituted. Each logical stream of intelligence includes its source and destination information to ensure it arrives where it needs to and when it is needed. This intelligent stream packet concept works for more than data. The same concept can just as readily be applied to voice as it is to text messages, pictures, moving video and other raw computer data.
Back to LTE
The move to LTE technology is based on the convergence of all of the aforementioned applications (voice, text, video and any other digitally supported information application) onto a single supported network model. Current 2G and 3G cell phone networks are a mixture of multiple support infrastructure platforms, whereas LTE promises a single platform capable of reducing the back end support hardware and maintenance costs. It also promises a more stable and incremental upgrade future. All of this is in support of reducing cost while expanding capabilities and, importantly, interoperability (in this case think roaming).
Now that you know what LTE is at a very high level, why is it important to you and your agency? One word: change.
Because we now have essentially one technology that can be used to transport virtually all of our intelligence streams, there will be a big push to “converge” and “standardize” the underlying infrastructure. Cost, efficiency, economy of scale, universal application and a viable future migration strategy are key components that will affect every public safety agency in the country.
Throughout the evolution of the commercial wireless market (cell phones/smart phones), public safety, not unlike any other private citizen, has been just a client. The wireless commercial systems haven’t catered to any of public safety’s unique needs, and public safety doesn’t have the mass to push for any significant requirements. This brings us to a significant opportunity for public safety.
The commercial wireless market has been evolving continually. The evolution has been referred to as the first generation (1G), second generation (2G), third generation (3G) and now fourth generation (4G). Each generation can be categorized largely by its capacity for not only quantity of voice and data capability, but the variety of services and applications it can deliver. The first generation of wireless service was pretty much relegated to simple telephony voice with some relatively slow data capability added at later. The 2G technology saw an expansion of data capabilities as the result of higher speeds for data transmission and the migration of voice to a digital platform. The 3G technology of wireless has been mostly an incremental upgrade in bandwidth and transmission speed. All three of these generations depended on the old circuit-switched concept for voice communications.
LTE is 4G technology, which like its predecessors provides even higher incremental bandwidth possibilities. There’s a bigger difference with 4G technology because it pretty much abandons the circuit-switched technology for an IP-based packet technology.
IP
As these wireless generations have progressed, the Internet has been growing, and the capabilities enjoyed by millions are now leaking into the mobile world. To call the new batch of second and third generation cell phones, “cell phones,” doesn’t begin to describe their capabilities. The capabilities of desktop and laptop computers are now being seen in palm-size devices — not to mention in a portable jukebox that also has a still and video camera. Automobiles are now becoming connected. Access to the Internet’s feature rich environment is even expected while on the go. Even the core of voice communications has been changing with the advent of VoIP (Voice over IP).
A significant amount of traffic is transported over the Internet as opposed to traditional telephone long-distance circuits (circuit-switched). IP-based phone systems are being installed by companies to replace now antiquated circuit-switched PBX systems. The move to fourth generation technology will fully embrace the power of packet-based technology in which virtually all information exchange will be transported over a common and consistent protocol. LTE is the convergence of all of the information technologies and is much, much more than just a cell phone technology.
700 MHz
LTE is still in development as a standard. Commercial deployment is scheduled by several commercial carriers starting in 2010. One requirement is spectrum — and lots of it — in the form of large contiguous blocks of bandwidth. This brings up the 700 MHz broadband spectrum assigned by the FCC, including the public safety block consisting of 10 MHz of bandwidth. We don’t yet know exactly how the situation with the public safety 700 MHz broadband spectrum will play out, but as of now, there’s a significant push to leverage a combination of the public safety broadband spectrum along with the adjacent block 10 MHz of 700 MHz spectrum recently allocated by the FCC for commercial implementation, which could result in a nationwide network. Public safety is already heavily subscribed to current 2G and 3G commercial wireless systems. The potentials now include a rather universal standardized system with very significant coverage and peak bandwidth capability (capacity). The benefits will potentially include economy of scale for end user equipment, transparent roaming across jurisdictions, even nationwide, and many new applications.
The public safety 700 MHz broadband block is currently licensed by the FCC to a single nationwide licensee referred to as the PSBL (Public Safety Broadband Licensee). The entity holding the PSBL license is the PSST[2] (Public Safety Spectrum Trust), which comprises 15 individual associations representing a broad swath of public safety practitioners. The actual implementation of the public safety 700 MHz spectrum has hit some snags. Originally slated by the FCC to be associated with and subject to the results of the auction of an adjacent commercial block of spectrum called the “D Block,” the public safety block is now sitting in limbo due to the failure of the commercial D-Block auction. The FCC is currently considering its options to proceed.
In the intervening time frame, several of the largest commercial carriers have committed to LTE as their chosen technology for the future. Several public safety organizations and associations have likewise endorsed LTE as the technology of choice, including the PSST, APCO, NENA, NPSTC, as well as other specific law, fire and EMS representative associations. Additionally, several large regional agencies and a few states have submitted requests to the FCC to access the public safety 700 MHz broadband spectrum to begin implementing their own localized broadband networks.
This is where LTE now becomes important to all public safety agencies. LTE has become the leading contender in the crystal ball of future wireless technologies. There are current initiatives to promote the development of public safety specific requirements for LTE both within the standard itself as well as the operational implications of LTE systems — an opportunity for public safety to be heard. The future of the public safety 700 MHz broadband block is still at stake with two or three potential directions. One proposal is to throw the public safety block back into the commercial pool with possible auction revenue generated promoting public safety networks (although undefined as to future or conventional incumbent systems). Another proposal (backed by the PSST and other major public safety agencies) is for the FCC to reallocate the failed commercial D Block to public safety and have the PSBL negotiate with commercial wireless carriers for its use in a shared commercial/public safety environment, but catering to the specific needs of public safety with universal interoperability and roaming as a goal. In the wings are local agencies and regional consortium as mentioned above that would like the opportunity to implement the technology in their own regions. In reality, these two later directions may have the best shot with the PSBL brokering activities.
Looking Ahead
Public safety is on the verge of great things that can be supported by broadband wireless. Why not? We know we have uses for broadband wireless based on the current adoption of commercial broadband subscriptions. What we need to guard is our ability to leverage the shear power of national and international economies of scale driven by the commercial sector and not fall victim to narrow-sighted visions of proprietary implementations. Public safety has fought hard to obtain a combination of capability, interoperability and cost management — something that has proved almost impossible in the two-way radio field, but very obtainable in the broadband wireless arena.
The direct impact on public safety comes from very different directions. The first obvious direction is the connectivity to the first responder on the street. As mentioned above, public safety has been using commercial services, including cell phones, with a significant number of agencies employing second and third generation data connectivity to provide applications to moving vehicles in the form of wireless cards for laptops, as well as smart phones. Always being inventive, many public safety agencies are integrating their existing low-speed data, mobile data and other services using internal proprietary wireless systems with commercial wireless systems to enhance coverage, capability and capacity. Public safety will surely use LTE when it’s provided by the commercial market.
LTE will not replace our current two-way radio requirements yet. Given time and the proper assertions from public safety, it may provide future replacement. It will be hard to replace the unique characteristics of our current “instant voice” requirements. LTE does provide a means and a path to get public safety back on track for all of the other mobile information applications we may desire. Who knows, we may eventually see a conventional handheld public safety radio with all the capabilities of a smart phone.
Money
Got your attention, right? 700 MHz spectrum is very valuable. This is a great leverage to get the services public safety needs. Commercial carriers can build significant systems and with access to public safety 700 MHz broadband spectrum these commercial entities may easily be enticed to address the capabilities, interoperability and coverage requirements unique to public safety.
Another money factor is in play. The current recession has seen its share of stimulus efforts. The American Recovery and Reinvestment Act, the National Telecommunications and Information Administration (NTIA), along with the Department of Agriculture’s Rural Utilities Service (RUS) program, is granting and loaning $7.2 billion in stimulus money to bring broadband to unserved and underserved areas. Although the Act doesn’t indicate public safety as a primary grantee, it does promote the addition and consideration of public safety needs as an element required in any such grant applications. Are you working with any local consortiums or individual, private and/or public institutions that are submitting grant request? If not, get to work. There’s an NTIA sponsored Web site where you can research the grant applications in your area.[3]
Our ultimate goal is to put tools in the hands of our first responders that allow them to effectively and efficiently execute their mission. To do that, we, collectively as the public safety community, need to be aware of this new technical direction, prepare for it and, above all, manage it.
About the Author
Ron Haraseth is a public safety technology specialist for SEARCH, the National Consortium for Justice Information and Statistics. He has more than 38 years of experience in the public safety field, and is a former director of Automated Frequency Coordination (AFC) Inc. He’s a licensed FCC general radio operator and also holds an FCC amateur radio license. He is a member of APCO International and the National Public Safety Telecommunications Council, and is a fellow member of the Radio Club of America.
End Notes
- Trademark for system technology developed by Motorola and currently used by Sprint for PTT capability.
- Public Safety Spectrum Trust: www.psst.org/index.jsp.
- National Telecommunications & Information Administration: www.ntia.doc.gov/broadbandgrants/applications/search.cfm.
Orginially published in Public Safety Communications, 76(2):16-21, 71, February 2010.