1G

Remember analog brick phones and bag phones way, way back in the day? Cell phones began with 1G. In the world of cell phones, the term 1G signifies first-generation wireless analog technology standards that originated in the 1980s. 1G was replaced by 2G (short for second generation) wireless digital standards.

1G was the first generation of wireless telephone technology — mobile telecommunications. The main difference between the two successful mobile telephone systems, 1G and 2G, is that the radio signals that 1G networks use are analog, while 2G networks are digital.

Figure 1:

The antecedent to 1G technology is the mobile radio telephone, or 0G.

2G

Cell phones received their first major upgrade when they went from 1G to 2G. In the world of cell phones, the term 2G signifies second-generation wireless digital technology. 2G networks saw their first commercial light of day on the GSM standard. GSM stands for Global System for Mobile communications. 2G on GSM standards were first used in commercial practice in 1991. In addition to the GSM protocol, 2G also utilizes various other digital protocols, including Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Integrated Digital Enhanced Network (iDEN) and Personal Digital Cellular (PDC). GSM is based on TDMA.

Three primary benefits of 2G networks over their predecessors were that phone conversations were digitally encrypted; 2G systems were significantly more efficient on the spectrum, allowing for greater mobile phone penetration levels; and 2G introduced data services for mobile, starting with SMS text messages.

After 2G was launched, the previous mobile telephone systems were retrospectively dubbed 1G. Whereas radio signals are analog on 1G networks, and digital on 2G networks, both systems use digital signaling to connect their radio towers to the rest of the telephone system.

Figure 2:

2G cell phones

2G technologies

2G technologies can be divided into TDMA-based and CDMA-based standards, depending on the type of multiplexing used. The main 2G standards are as follows:

GSM (TDMA-based) is used on all six of the major inhabited continents.

IS-95, a.k.a. cdmaOne (CDMA-based), is used in the Americas and parts of Asia.

PDC (TDMA-based) is used exclusively in Japan.

iDEN (TDMA-based) is a proprietary network used by Nextel in the United States and Telus Mobility in Canada.

IS-136, a.k.a. Digital AMPS or D-AMPS (TDMA-based), was once prevalent in the Americas, but most have migrated to GSM.

2.5G services enable high-speed data transfer over upgraded existing 2G networks. Beyond 2G is 3G, with higher data speeds, and even evolutions beyond 3G, such as 4G.

2.5G

Before making the major leap from 2G to 3G wireless networks, the lesser-known 2.5G interim standard was used. In the world of cell phones, 2.5G wireless technology is a stepping stone that bridged 2G to 3G wireless technology. While 2G and 3G have been formally defined as wireless standards, 2.5G has not been, and was created only for the purposes of marketing. As an interim step from 2G to 3G, 2.5G saw some of the advances inherent in 3G networks (including packet-switched systems). The evolution from 2G to 3G ushered in faster and higher-capacity data transmission.

Note:

2.5G does not necessarily provide faster services, because bundling of timeslots is used for circuit-switched data services as well.

2.5G provides some of the benefits of 3G and can use some of the existing 2G infrastructure in GSM and CDMA networks. General Packet Radio Service (GPRS) is a 2.5G technology used by GSM operators. Some protocols, such as Enhanced Data rates for GSM Evolution (EDGE) for GSM and CDMA2000 1x-RTT for CDMA, can qualify as 3G services because they have a data rate of above 144 kbit/sec, but are considered by most people to be 2.5G services (or 2.75G, which sounds even more sophisticated) because they are several times slower than "true" 3G services.

3G

Following 2.5G, 3G ushered in faster data-transmission speeds, so cell phones could be used in more data-demanding ways. This has meant streaming video, audio and much more. Cell phone companies today are spending a lot of money to brand the importance of their 3G networks. But what is 3G, really, and where did it come from? 3G is the third generation of mobile phone standards and technology. 3G supersedes 2G technology. 2.5G was a temporary bridge between 2G and 3G. 3G technologies enabled faster data-transmission speeds, greater network capacity and more advanced network services. The first pre-commercial 3G network was launched on May 2001, and the first commercial launch of 3G in Japan followed on Oct. 1 of the same year.

International Mobile Telecommunications-2000 (IMT-2000), better known as 3G or 3rd Generation, is a family of standards for mobile telecommunications defined by the International Telecommunication Union (ITU), which includes GSM EDGE, Universal Mobile Telecommunications System (UMTS), and CDMA2000, as well as Digital Enhanced Cordless Telecommunications (DECT) and WiMAX. Services include wide-area wireless voice telephone, video calls and wireless data — all in a mobile environment. Compared to 2G and 2.5G services, 3G allows simultaneous use of speech and data services and higher data rates (up to 14.0 Mbit/s on the downlink and 5.8 Mbit/s on the uplink). Thus, 3G networks enable network operators to offer users a wider range of more advanced services while achieving greater network capacity through improved spectral efficiency.

3G Features

Data rates - ITU has not provided a clear definition of the data rate that users can expect from 3G equipment or providers. Thus, users who are sold 3G service may not be able to point to a standard and say that the rates it specifies are not being met. While stating in commentary that "[…]it is expected that IMT-2000 will provide higher transmission rates: a minimum data rate of 2 Mbit/s for stationary or walking users, and 348 kbit/s in a moving vehicle," the ITU does not actually clearly specify minimum or average rates or what modes of the interfaces qualify as 3G, so various rates are sold as 3G, intended to meet customers’ expectations of broadband data.

Security - 3G networks offer a greater degree of security than that of their 2G predecessors, by allowing the user’s equipment to authenticate the network to which it is attaching.

Applications

3G offers a wide range of applications, which are mainly made possible due to the enhanced data rates as a result of the 3G’s 2 Mbps bandwidth availabilities. The following list describes some of the applications:

Mobile TV. Due to the high data-transfer rate being offered by 3G, TV can be viewed on mobile phones. For this service, the user must tie up with a service provider, through which the content can be accessed.

Videoconferencing. It is possible to conduct a video conference by using the available network, thanks to the 2 Mbps bandwidth.

Tele-medicine. This extended feature of videoconferencing enables a person to be examined remotely by a doctor who is located at a different place.

Location-based services. These services, accessed via the service provider, include weather updates, viewing live road and traffic conditions and tracking vehicles.

Video on demand. Videos can be viewed on demand from a service provider. Again, this feature is possible thanks to the high buffering speeds that are possible on the 3G network.

Issues

Although 3G has been introduced successfully to users around the world, some issues are debated by 3G providers and users:

Expensive input fees for the 3G service licenses in some jurisdictions

Differences in licensing terms between states

Level of debt incurred by some telecommunication companies, which makes investment in 3G difficult

Lack of state support for financially troubled operators

Cost of 3G phones

Lack of coverage in some areas

Demand for broadband services in a handheld device

Inadequate battery life in 3G phones

Evolution Toward 4G

Both 3rd Generation Partnership Project (3GPP) and 3rd Generation Partnership Project 2 (3GPP2) are currently working on further extensions to 3G standards, named Long Term Evolution (LTE) and Ultra Mobile Broadband (UMB), respectively. Being based on an all-IP network infrastructure and using advanced wireless technologies, these specifications already display features characteristic of International Mobile Telecommunications Advanced (IMT-Advanced), or 4G, the successor of 3G. However, falling short of the bandwidth requirements for 4G (1 Gbit/s for stationary operation and 100 Mbit/s for mobile operation), these standards are classified as 3.9G or Pre-4G.

3GPP plans to meet the 4G goals with LTE Advanced, whereas Qualcomm has halted development of UMB in favor of the LTE family.

On December 14, 2009, TeliaSonera announced in an official press release that it would be the first operator in the world to offer customers 4G services. With the launch of this network, initially TeliaSonera is offering services in Stockholm, Sweden and Oslo, Norway.

4G

No technology would be complete without a looming upgrade for tomorrow. What’s on the horizon for 4G? What improvements will it bring beyond 3G, and when might we expect 4G to go live? Following the evolutionary line of cell phone technology standards spanning 1G, 2G, 2.5G and 3G, 4G describes the entirely brave new world beyond advanced 3G networks. 4G, which is also known as beyond 3G or fourth-generation cell phone technology, refers to an entirely new evolution and a complete 3G replacement in wireless communications. Just as data-transmission speeds increased from 2G to 3G, the leap from 3G to 4G promises even higher data rates than existed in previous generations. 4G promises voice, data and high-quality multimedia in real-time (“streamed”) form — all the time and anywhere. Various standardization and regulatory bodies estimate the launch of 4G networks commercially between 2012 and 2015.

4G is being developed to accommodate the quality-of-service and rate requirements set by further development of existing 3G applications such as wireless broadband access, Multimedia Messaging Service (MMS), video chat and mobile TV, but also new services such as HDTV content, minimal services like voice and data, and other services that utilize bandwidth. It may allow roaming with wireless local area networks, and be combined with digital video broadcasting systems.

Following are the objectives of the 4G wireless communication standard:

Flexible channel bandwidth, between 5 and 20 MHz, optionally up to 40 MHz.

Spectrally efficient system (in bits/s/Hz and bits/s/Hz/site).

High network capacity, with more simultaneous users per cell.

Nominal data rate of 100 Mbit/s while the client physically moves at high speeds relative to the station, and 1 Gbit/s while client and station are in relatively fixed positions as defined by the ITU Radiocommunication Sector (ITU-R).

Data rate of at least 100 Mbit/s between any two points in the world.

Smooth handoff across heterogeneous networks.

Seamless connectivity and global roaming across multiple networks.

High quality of service for next-generation multimedia support (real-time audio, high-speed data, HDTV video content, mobile TV, etc.).

Interoperability with existing wireless standards.

IP packet-switched network.

4G Features

According to the members of the 4G working group, the infrastructure and the terminals of 4G will implement almost all the standards from 2G to 4G. Although legacy systems are in place to adopt existing users, the infrastructure for 4G will be exclusively packet-based (all-IP). Some proposals suggest having an open Internet platform. Technologies considered to be early 4G include Flash-OFDM (orthogonal frequency-division multiplexing), the 802.16e mobile version of WiMax, and High Capacity Spatial Division Multiple Access (HC-SDMA).

Summary

In the history of mobile communications, repeated attempts have been made to reduce a number of technologies to a single global standard. Projected 4G systems offer this promise of a standard that can be embraced worldwide through its key concept of integration.

Future wireless networks will need to support diverse IP multimedia applications to allow sharing of resources among multiple users. There must be a low complexity of implementation and an efficient means of negotiation between end users and wireless infrastructure. The fourth generation promises to fulfill the goal of PCC (personal computing and communication) — a vision that affordably provides high data rates everywhere over a wireless network.