The Evolution of Mobile Networks

Mobile phone technology has been available to consumers for only 30 years, but there have been some amazing advancements in that time. Since the first limited commercial rollout in 1983, there have been four distinct generations of technology. These have gone from basic radio communication with a limited connection range and poor quality voice to smartphones capable of managing high-quality voice while taking and sending a 7-megapixel picture with no noticeable drop in quality. This section reviews each generation of cell phone technology, looking at what it was, how it worked, and what the security implications were and are.


AMPS 1G
A commercial cellular system, called the Advanced Mobile Phone System (AMPS), was deployed in the North America in 1993. AMPS used analog signals to connect to cell towers, using FDMA for channel assignment. AMPS succeeded where previous attempts to create a commercial cellular service failed because of its ability to reuse frequencies (FDMA) and to hand off calls between cells in a relatively seamless way that did not involve the user.

The AMPS system was a commercial success despite serious performance issues. Call quality and reliability were nowhere near that of the PSTN, which limited its usefulness. In addition, FDMA, while considered a breakthrough, still consumed a lot of bandwidth per channel, which limited capacity. AMPS calls were also unencrypted, making it possible to eavesdrop on a call using a scanner. Finally, AMPS phones were relatively easy to clone, allowing non-subscribers to gain access to the service.

Although much-improved second-generation technology soon came along, carriers continued to support AMPS phones until 2002, when the older technology was finally phased out.


GSM and CDMA 2G
The big change from 1G to 2G was the conversion from analog to digital. Initially referred to as Digital Advanced Mobile Phone System (D-AMPS), 2G cellular phones and networks used TDMA, which greatly improved bandwidth efficiency and subscriber capacity.

Unlike AMPS, which was essentially the same everywhere it was deployed, two distinct systems emerged for D-AMPS. The first of these was a TDMA-based second-generation technology developed in the late 1980s by an industry consortium consisting mostly of European companies. This technology was called Groupe Spécial Mobile (GSM), although its name was later changed to Global System for Mobile (GSM). The use of GSM was mandated throughout Europe to ensure continent-wide compatibility between countries.
The second major 2G technology was CDMA, which refers to both the cellular system and the method of subscriber access. CDMA was the dominant 2G system used in the U.S. While CDMA and GSM were not compatible, dual-system phones were eventually developed that could operate on either system.

In addition to offering more efficient use of bandwidth, 2G systems also used encryption, which greatly improved security. One of the downsides, however, was that the lower power requirements of digital systems meant that coverage was often poor outside populated areas, which had greater cell density. Another problem with digital was that unlike an analog signal, which degrades in a linear way, digital signals drop off completely when the signal strength falls below a certain threshold. When it's good, digital quality can be very good. But when it's bad, it's essentially unusable.

This 2G technology was the precursor to mobile data networks. The first of these was used for Short Message Service (SMS), which introduced the world to texting. At first, SMS did not seem like a compelling feature. But its use exploded with teens and young adults to the point where many used their phones only for texting. Eventually, subscription plans were created to accommodate these users.


GPRS and EDGE
Although GSM and CDMA were digital technologies and took advantage of multiple access techniques, both were still circuit-switched technologies, much in the way the PSTN was. General Packet Radio Service (GPRS) was the first packet-switching technology method that allowed data sharing over mobile networks. Still considered a 2G technology but often called 2 + or 2.5G, GPRS allowed access to some Web sites—although data rates proved to be too slow for what was becoming a growing need and expectation.

EDGE, which AT&T rolled out in 2003, and which other carriers quickly offered, represented an enhancement over GPRS. It offered high data rates through better data encoding and (at that time) viable data access to many Web sites.


3G Technology
The third generation of mobile technology, called 3G, was the first generation specifically designed to accommodate both voice and data. Based on the International Mobile Telecommunications-2000 (IMT-2000) standards set by the International Telecommunications Union (ITU), 3G can accommodate voice, data, and video.

The first 3G system was rolled out in Japan in 2001. In 2002, it was rolled out in many other parts of the world, including the U.S. and the European Union. Implementation of 3G took longer than anticipated, however. This was in large part due to the need for expanded frequency licensing to accommodate higher bandwidth needs and rapidly increasing subscriber rates. By the end of 2007, however, there were 190 3G systems online in more than 40 countries worldwide.

The most noticeable improvement in 3G was its high-speed data rates. One enhancement to 3G was a mobile protocol called High Speed Downlink Packet Access (HSDPA), which improved data rates to an impressive 14 Mbps. For the first time, the streaming of music and video to mobile devices was supported. Responding to this capability, many content providers created streaming offerings that catered specifically to mobile users.

In addition to the security benefits of 2G, such as encryption, 3G systems also allowed for network authentication, which ensured that users connected to the correct network. On the negative side, smartphones that attached to 3G networks had far more personal-data capabilities—for example, access to bank accounts—as well as access to corporate systems and applications. With the growth in the number of users and an increase in the types of opportunities to exploit, 3G systems and smartphones soon attracted the attention of cybercriminals.


4G and LTE
As of this writing, mobile telephony is in its fourth generation, called 4G, while the fifth generation, called 5G, is in development. Among other improvements, 4G is an all-IP network, allowing the use of ultra broadband and the promise of 1 Gbps data rates. At that throughput level, voice communications can be converted to Voice over IP (VoIP) with high quality, high-definition TV can be streamed to mobile devices, and a host of live interactive gaming applications can be enjoyed.

The two systems currently deployed for 4G are Mobile Worldwide Interoperability for Microwave Access (WiMAX) and Long Term Evolution (LTE). The standards for 4G were developed by the ITU as the International Mobile Telecommunications Advanced (IMT-Advanced) specification. 4G also supports IPv6, which is especially important given the growth of smart devices.

An important change in 4G is the authentication method used. Previous systems used a signaling system called Signaling System 7 (SS7) to set up calls and mobile data sessions. In contrast, 4G uses a signaling protocol called Diameter. Some critics say Diameter sessions are potentially open to hijacking or having users' personal information exposed, making it a less-than-ideal replacement for SS7. In addition, the fact that 4G is an all-IP network opens it up to all the Internet's known security issues. Given the vast amounts of private, personal information, as well as company information, stored on or captured from mobile devices, this represents a significant security vulnerability for both individuals and businesses.

Taken from : Wireless and Mobile Device Security