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The Future of Wireless after 3G

As we enter 2010, the wireless technology migration path continues with the next generation 4G wireless networks. Many are wondering just how any of it relates to law enforcement. Let’s take a look at the process that got us here, from the origins of wireless communication, all the way to where we are today at 3G, 3.5G, and then to the future 4G LTE and WiMAX technologies.

Technologies known as Mobile Telephone System (MTS) and Advanced Mobile Telephone System (A-MTS) pre-date cellular telephone systems (1945-1980) and are what you see in old James Bond movies. They were switched by a human operator in high site/high power sites without hand-off capabilities.

Essentially, the first version of GSM phones on analog GSM systems, which existed for a few years, became the digital systems. The first generation was analog cellular (called AMPS) which existed from 1980 to 2000, and Verizon still had AMPS in rural areas in 2000. Somewhere along the way, the FCC mandated turning off these sites for more spectrally efficient technologies.

The second generation was digital cellular, which started with GSM in 1991 in Europe. GSM is a TDMA technology which arrived in the United States a couple years after that, and CDMA came to the United States in 1995 as an alternative 2G technology. While CDMA has seen pockets of success around the world, GSM has been by far the dominate cellular technology for voice communications. Both CDMA and GSM technologies have evolved to support data.

Current Technology

Currently there is a plethora of technologies, most supporting relatively low bandwidth data applications such as MMS and low Internet browsing with data rates of 30kbps to 150kbps.

Everyone has heard of GSM, which stands for Groupe Spécial Mobile in French, renamed in English as Global System for Mobility. GSM operates in several bands including the 850MHz band, which is used mostly in Latin America; the 1900MHz bands, which are mainly used in the United States; and the 900MHz and 1.8MHz bands, which cover the rest of the world. GSM is the standard that is used by approximately 80% of the 3.8 billion cellular subscribers.

That said, the CDMA carriers in the United States, including Sprint, Verizon, Metro PCS and others, may not be necessarily moving to HSPA and GSM. It might be more likely that a few of them have selected LTE as a migration path from their existing CDMA genre. But if they use NEW spectrum, then they would not be removing the CDMA to use LTE—that would be an overlay. LTE is part of the GSM evolutionary path beyond 3G technology. The overall objective for LTE is to provide an extremely high performance, radio-access technology that offers full vehicular speed mobility and that can readily coexist with HSPA and earlier networks.

GSM and SIM Cards

You know you are using a GSM device if your handset has a SIM card in it. A Subscriber Identity Module (SIM) is part of a removable smart card Integrated Circuit Card (ICC), also known as SIM Cards, which are used in mobile cellular telephone devices and mobile computers. SIM cards securely store the service-subscriber key (IMSI) used to identify a subscriber, and they also store small amounts of subscriber information such as phone numbers and names for speed dial.

The SIM card allows users to change phones by simply removing the SIM card from one mobile phone and inserting it into another mobile phone or broadband telephone device. Alternatively, CDMA is a flash code for subscriber identification and can only be moved from phone to phone through approved updates by the managing carrier and by physically taking the phone to a location to have the unit realigned for use in the CDMA network.

General Packed Radio Service (GPRS) delivers to most users an average experience of around 30kbps to 50kbps. Many users experience GPRS when using their mobile browser in fringe areas, and it works well enough, but not as well as it could. GPRS enables services such as multimedia messaging service (MMS), which allows the transfer of pictures and music, and basic mobile Internet. GPRS could enable much faster communications (115kbps), but the retail consumer decided it was still not enough compared to what they had at home.

Next came Enhanced Data Rates for GSM Evolution (EDGE), also known as Enhanced GPRS (EGPRS), which is a backward-compatible technology for GPRS. A pretty recent standard allows for much faster downloading. Because mobile devices have become both video players and music players, people needed to be able to watch streaming video and download mp3 files faster.

Third Gen Technology

Moving forward again, we transitioned to what we know as third generation technologies. Universal Mobile Telecommunications Standard (UMTS) was created in 1996 at a UMTS forum in Zurich by the 3GPP (the 3rd Generation Partnership Project), which is a consortium of literally every manufacturer and service provider in the GSM world.

The 3GPP is a collaboration among groups of telecommunications associations that aim to make a globally applicable third generation (3G) mobile phone system specification within the scope of the International Mobile Telecommunications-2000 project of the International Telecommunication Union (ITU). 3GPP standardization encompasses Radio, Core Network and Service architecture to support the creation of UMTS, subsequent HSDPA, HSUPA, HSPA, HSPA+ and eventually LTE.

Motorola, like many companies, was there from the beginning supporting the design of these networks, and like Nortel and many others that spent millions on the design, they all had a part in it. These networks’ original purpose was for enabling long expected videoconferencing. The other name it goes by is 3GSM, which literally says that UMTS is 3 times better than GSM.

3.5G Technology

Today we mostly use what is referred to as 3.5G or 3G+ technology. High Speed Packet Access (HSPA) is theoretically six times faster than UMTS (up to 3.6 Mbytes/sec)! Practically speaking, this would mean that to download an mp3 file would take about 30 seconds instead of something like two minutes. This is fast for a typical patrol application because most of law enforcement is using mobile computing systems running Computer Aided Dispatch (CAD) software and Mobile Data Application that don’t require that kind of speed.

The only time an agency would need this kind of speed would be if they were downloading or streaming video from the vehicles back to a dispatch or a command room. Sprint, Verizon, Metro PCS and U.S. Cellular are all staying with CDMA and either moving to LTE or enhancing with EV-DO Rev A networks in the CDMA family. Verizon and Sprint continue to use CDMA1X for voice and EV-DO for data, and Verizon has publicly stated it will deploy LTE in 2010. GSM-based carriers like TMobile, AT&T and similar 3GPP members are migrating to HSPA.

Around North America, several carriers in Canada and Mexico will continue to maintain CDMA networks as well. These technologies are not backward compatible. UMTS is a CDMA-based technology which cannot co-exist with TDMA-based technologies such as GSM and EDGE. Any backup ability requires the device to fall back to another channel.

In other words, the cell phone has multiple technologies allowing it to fall back. Take the CDMA1X / EV-DO phones, for instance, which also support GSM/EDGE allowing roaming and fallback, assuming the user has subscription access to other networks. Phones exist today on the market that support both CDMA-1X- and 3GPP-based technologies. Of course these phones include a SIM which allows them to connect to the 3GPP system.

The 4G and WiMAX

The next generation 4G networks provide another leap in technology. Most cellular carriers have adopted Long Term Evolution (LTE) as their 4G technology. Similar to WiMAX, LTE is Orthogonal Frequency-Division Multiplexing (OFDM) and provides another leap in end user experience. The next generation 4G wireless broadband systems will enable access to media-rich information from anywhere at anytime, thus delivering better information to the front line and enabling them to make more informed decisions based on increased situational awareness, better collaboration and increased productivity.

The 4th generation wireless networks have two competing versions known as WiMAX and LTE. WiMAX, which was at one point seen as offering significant cost and time advantages, is being deployed in the U.S. by several smaller regional carriers, but by and large is being deployed on a nationwide level by Clearwire.

WiMAX coverage has reached more than 24 cities with Clearwire and continues to expand, although LTE is coming right behind it with commitments from Verizon and AT&T among other regional players. It is predicted that in time, perhaps by 2013, LTE will provide greater coverage than WiMAX is providing in the United States. But both technologies will remain in place and serving customers across the U.S.

WiMAX and LTE share many of the same technological advances and thus have similar performance capabilities. The differences are likely to be in where and how they are deployed. LTE aligns very well with 700MHz spectrum in the U.S., serving carrier programs and requirements, while WiMAX aligns very well with the 2.5GHz in the U.S. This is used primarily for mobile Internet access by ISPs like Clearwire and many other smaller providers that are not traditional cellular carriers but that have spectrum outside the United States.

The traditional cellular systems mentioned above serve voice with circuit digital connections, but prior to 4G all systems (both GSM- and CDMA-based) do not use VoIP. The 4G technologies like WiMAX and LTE are moving toward data rates expected to reach a previously unachievable 100 Mbytes/sec.

The Downside

The only downside is almost all of the existing cellular-based handsets on the market today are not 4G compatible because they don’t have the 4G radio modem and frequencies built in. Yes, 4G means a new handset with yet another modem inside the device. It’s not a firmware flash or software upgrade, it’s hardware. Probably the simplest way to explain the differences between 3G and 4G would begin with increased data rates and extremely low latency.

LTE expected user data rates are theoretical and have many factors that affect performance—distance to cell site, cell site loading, subscriber or carrier speed throttles, indoor penetration and outdoor obstacles, just to name a few. If the user has a strong signal, no obstructions and is close to a cell site that’s not overloaded, the speeds should be comparable to a wired broadband connection. This is good news for areas that have no fixed cable Internet. Latency will also improve with LTE. Latency is the time it takes the user to initiate a connection.

Typically, with 3.5G networks you would see a 2 to 8 second delay on the first connection, but now with LTE you should see an initial connection of approximately 800 milliseconds with subsequent latencies of 15ms to 40ms. For the user, this results in an incredible responsiveness not seen before in a wide area wireless connection, regardless of technology.

LTE and E911

There have been rumors floating around that LTE technology will not support current E911 Emergency calling, but nothing could be further from the truth. VoIP support for emergency calls (including location support) is specified as part of LTE Release 9. A transition solution exists which is falling back to 3G/2G for completing emergency calls.

However, to handle the situation of a fallback network not existing, this enhancement was completed in Release 9. This gives the operator the option of supporting the regulatory requirements for LTE VoIP calls both for phones that can register for normal services and for those in limited service, including the USIM-less case. Also, the emergency call callback from the Public Safety Answering Point (PSAP) and its interaction with the possibly activated supplementary services is specified.

The industry continues to move forward in anticipation of dedicated spectrum that will soon be available for public safety, and industry players have made some important progress toward making 4G for public safety a reality. This commitment by the FCC and Congress to support the needs of public safety in dedicated spectrum would allow law enforcement to OWN their networks and, as such, align LTE, a commercially available technology to fit the specific needs of mission critical responders.

Single 4G Standard

The Assocation of Public-Safety Communications Officials (APCO) and the other voting members of the National Public Safety Telecommuni-cations Council (NPSTC) appear to have aligned behind a single 4G standard, Long Term Evolution (LTE). The NPSTC is a federation of organizations whose mission is to improve public safety communications and interoperability through collaborative leadership.
The public safety industry has reiterated support for the Public Safety Spectrum Trust (PSST) to serve as the managing agency for public safety spectrum.

Motorola is a leader in the development of LTE and WiMAX technologies. Recently Motorola published several white papers on the transition to 4G networks and the impact of those networks on public safety. Motorola suggested there are five key questions to consider before implementing 4G in your agency.

Who exactly are the end users of this new technology and what does it provide them versus previous technologies? Police are obviously the users most in need of the new technologies that will be enabled by 4G systems. Anywhere, anytime access to information will arm them with better information in real-time so that they can make better decisions.

Other Users and M2M

Other potential users of 4G networks exist as well, and sharing network resources with government administration, public works and other government departments could greatly improve productivity and offset some of the costs of future 4G networks.

Another way to potentially offset the costs of future 4G networks is by taking advantage of the additional bandwidth they provide to deploy more “unmanned” devices, such as parking meters, traffic sensors or video surveillance systems. Nicknamed M2M (Machine to Machine applications), these “electronic eyes” can serve as force multipliers and free up invaluable first responder human resources.

For example, can you imagine a detective who normally only carries a cell phone having the ability to use that LTE cellular device on a VoIP Police land mobile radio system? Or what about a hand-held device used by a parking enforcement officer that gets real time GPS location information on parking meters that are currently occupied by expired vehicles? Or on the contrary, displays the GPS location of meters that are occupied with fully paid vehicles not requiring attendance? You can start to see the efficiency opportunities with 4G networks and the bandwidth they will offer.

From sharing video transmissions with the command center, to accessing mug shots of potential suspects, to supporting license plate recognition systems—the possible applications for 4G are almost endless. Some applications are very bandwidth intensive, while others require relatively short bursts of data.

For instance, e-mail attachments and content-rich database queries tend to place high bandwidth demands on the network while other applications, such as location-based service, presence or push-to-talk (PTT) voice, require little data and illustrate the advantages of low delay network latency mentioned early. Real-time video, requiring both high bandwidth and short delay low latency, is perhaps the most demanding application on a network.

Real-Time Video

Research shows there are many municipalities that want to give their first responders access to real-time video as they are headed toward a crime scene. Understanding which applications will be used and how they will be used is critical to designing a system that can effectively support the required traffic demands. This illustrates how device and application planning on a “Private LTE Broadband Public Safety” network combines the advantages of open carrier standards compliant interfaces into specific products and services that can enrich the mission critical experience.

Which 4G devices are right for my organization? The fact that LTE is most likely going to be the worldwide 4G standard protocol means all the peripheral equipment manufacturers will have the benefit of economies of scale when producing radio hardware. The availability of multiple types of devices, including fixed modems, rugged handhelds, data adaptors and rugged vehicular modems, will be cost effective.

The bad news is that device choice can also significantly affect network design. A low-powered portable device used primarily at pedestrian speeds has very different characteristics and network requirements than a high-powered vehicular modem traveling at 120 mph. Smaller devices may transmit at power levels less than 300mw, while vehicular modems can deliver 10X or more with unlimited vehicular power supplies and signal enhancing antennas.

Pick User-Friendly 4G

Public safety organizations should examine characteristics such as throughput and power requirements in any 4G devices they select. And as public safety organizations make choices about which 4G devices they want to carry, it is critical to remember one thing: They need to make sure they select 4G devices that are extremely easy to use. Front line responders have enough to think about, and they don’t need to be troubleshooting wireless devices.

What level of service does my organization need to support? The applications and devices that first responders use can also impact the minimum acceptable service level that the 4G network must support. First responders might also have difficulty operating some devices indoors, unless the network is designed with a more aggressive site density to support in-building needs, which of course ultimately increases the cost of the network.

In addition, different levels of service may be needed for the various users, applications or incidents. For example, a building inspector accessing building permits may not need the same level of priority access as a firefighter downloading a building floor plan. Likewise, an officer responding to a burglary alarm may need higher priority than another officer filing a report.

4G Co-Exist with P25

How will the 4G network co-exist with other networks? Most public safety agencies have already invested in P25 or another narrow band mission critical communication system and want to get the most out of that investment. The good news is that deploying a 4G network does not require the removal of existing wireless voice or data networks.

In fact, existing networks will be maintained to support existing mission-critical voice, while the new 4G networks can be deployed to support new mobile broadband services. Even when 4G systems are widely deployed, narrow band systems will still play a key role in first responder communications.

Broadband networks can also overlay and inter-operate with narrow band data networks and WiFi mesh networks to balance coverage and capacity for data applications. Alternatively, public safety agencies may wish to partition their 4G network by keeping mission-critical users separated from government administration users. The advent of interoperable 4G networks nationwide will make it possible for law enforcement officials to use advancements in video and other technologies to do their jobs better than ever before.

Law enforcement organizations need to be clear on what operational requirements they have and what features are most mission critical. Do their front line users need to have on demand video within seconds? Can they migrate a specific group of users to 4G while maintaining less demanding users on a legacy network? Only by taking the time to ask the right questions today will they be best positioned to take advantage of the crime-fighting 4G communications tools that will be available in the future.

Sergeant Brad Brewer is a 22-year member of the Vancouver Police Department. He sits on the Ford Police Advisory Board and regularly gives presentations at Law Enforcement conferences on mobile computing, wireless technology and police vehicle ergonomics. He can be reached at

Published in Law and Order, Jan 2010

Rating : 5.0

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