Cellular Network Generations
A "Wireless Solutions Fast Start" Article

We read in the press that cell phone carriers are offering 2.5 services, and even 3G services. This article (longer than most but easy) will explain the various generations of cellular networks.  This is not just a history lesson. An enterprise may have customers or employees distributed over a wide geography, and that servicing them will require providing services on a variety of technologies that are completely incompatible or have vastly different performance characteristics. 

1G

First generation services were analogue services for cell phones.  These were (and are) for voice only; the technology didn't provide for SMS or other data services.  

1G is circuit switched.  This means that when you place a call, a connection is established for you, and is maintained until you hang up. You are billed for the duration of the call, regardless of how much talking occurred.  This is appropriate for voice communication where one person or the other is talking at any point in time.  

2G

Moving from 1G to 2G saw the transition from analogue to digital.  As in other areas, the impact of going digital was revolutionary.  The transition provided the ability to store, copy, encrypt and compress data, and allowed data transmission without loss and with error-correction.

It provided wireless cellular data services such as internet access, with speeds of 14.4.kbps (theoretical), 9.6 kbps - 19.2 kbps (real).  In addition, voice quality improved.  2G was also circuit-switched; you still paid for total connection time.  This is less appropriate for data than voice, as data is often "bursty", with periods of transmission activity and then periods of silence.  This is not a good deal for the consumer or the carrier. The consumer has to pay for dead time, and the carrier has to reserve a slice of spectrum which could be sold to someone else. 

Competing 2G Technologies

The generic term for 2G services is PCS (Personal Communications services).  There are two 2G technologies in Canada, GSM and CDMA, that are incompatible with each other in every respect.  This incompatibility explains some things about the evolution of the market and carrier relationships. 

• GSM stands for Global System for Mobility. It is based on a time-sharing process in which a slice of spectrum is shared between multiple users, by dividing creating small time-slices and allocating a slice to each user in turn.  One of the big benefits of GSM is its coverage. It is the standard 2G technology in Europe, with the potential for roaming 90+ countries with same phone. Globally, 70% of the world's digital subscribers are on GSM.  Both Rogers Wireless and Microcell use GSM. 
• CDMA stands for Code Division Multiple Access. It is an elegant technology, but also a complicated one that cannot be described in a few words.  Both Bell Mobility and Telus Mobility use CDMA.

2.5 / 3G

Moving from 2G to 2.5G / 3G introduced another revolutionary change, the introduction of packet switching for data rather than circuit switching.  Packet switching is an unlikely seeming technology that breaks a message into pieces and sends each piece individually across the network, together with control information on whether it is the first, second, etc packet in the set.  The packets travel through the network to their destination, possibly taking different paths depending on network conditions, where they are reassembled in the correct order.

For the consumer, packet switching provides two benefits.   First, the commodity being sold is packets, not network time connected, so the pricing model becomes more data oriented.   The consumer does not have to pay for dead time.  Carriers provide a large variety of data oriented plans, just as they do with basic cell phone plans.  For example, 1MB of data sent might cost up to $6 -7.  Each packet requires a significant amount of control information to route and sequence the packet, so your actual data may be less than 1MB.  

The second benefit to the consumer is that the internet is "always-connected" or "always-on".  There is no need to make a connection or hang up; users experience constant connection to the internet, just like home subscribers of ADSL or cable internet connection.  

There is another benefit to consumers of 2.5 / 3G services, and that is speed. They have a theoretical maximum speed of 115 kbps, with real speeds around 56 kbps (a common speed for dial-up connections to the internet).

The two 2G technologies in Canada extend to two 2.5G technologies, GSM/GPRS and 1XRTT, likewise incompatible in every respect.  

• GPRS stands for General Packet Radio Service, and is a data-oriented technology extending the GSM voice services. Rogers and Microcell use GSM/GPRS.  Microcell was the first player out of the gate in June 2001, but is now wondering if it can stay in business.  Rogers AT&T Wireless provides GPRS coverage to more than 93% of the Canadian population.  This does not mean coverage of 93% of the Canadian geography, due to the concentrations of population, and there are many places where coverage would be desirable but is unavailable, such as in the oil patch and rural areas.  
• 1XRTT is an abbreviation for CDMA2000 1XRTT and is usually abbreviated further to 1X.  It is the current generation system used by Bell and Telus. Bell launched their service early in 2002 in the greater Toronto Area early 2002.  Bell claimed cruising speeds of 86 kbps, compared to 56 kbps for dialup modems.

"True" 3G

Third-generation specifications call for even higher speeds 144 kbps in vehicles, 384 Kbps for pedestrians outdoors, and 2.48 Mbps in indoor offices.  Some carriers are calling their current deployments 3G.  This is contested by others as being the lowest rung of the 3G specification, and hence prefer to use the term 2.5G.  As expected, each of the 2.5G technologies has a forward path to the 3rd generation.

• EDGE (Enhanced Data Rates for Global [or GSM] Evolution) is the true 3G offering along the GSM path.  It provides data rates three times greater than GSM/GPRS, with speeds in the range 100 - 130 kbps (up to 200 kbps in bursts).  EDGE was rolled out across Canada in 2004.  Being an extension of GSM/GPRS, EDGE will be widely available internationally, and supported by network operators in many countries, and over 60 network operators in over 40 countries have committed to EDGE for their next generation services.
• There are a couple of forward paths from CDMA2000 offering substantially higher data rates. Neither of the CDMA based carriers (Telus Mobility, Bell Mobility) had announced offerings or pilots at the time or writing.

Next Generation

There are specifications for higher speed services.  We will update you when these become closer to reality in Canada.

 

Martin Stares is a respected speaker, author and coach in the field of wireless solutions and strategy for business, helping companies find innovative wireless solutions for their organizations. For more information and resources, visit Greyfriars Consulting Group at www.greyfriars.net. Read other articles in this series This article is one of a series call Wireless Solutions Fast Start, a course helping companies and individuals understand the business uses of wireless technologies. Visit www.greyfriars.net for other articles in this course. Free content for your web site Would you like to add this article and many others to your web site at no cost? The Greyfriars Wireless Solutions articles may be used on your site as long as the following conditions are met. The full content and links of each article must be used. The author and copyright notice must stay intact. The last paragraph describing the author and their business along with the link to their web site must be intact. If you do use one of our articles, drop us a line at enquiries@greyfriars.net so we can visit your site.