GSM Platform Evolution Steps

• Figure shows the GSM evolution steps according to how it is seen by most of the major cellular network suppliers and operators. The development is seen to go towards the 3G via intermediate high bit rate mobile communications systems.
• The global GPRS market, together with HSCSD, is now beginning to take off. The introduction of GPRS is one of the key steps in the evolution of today’s GSM networks to 3G. GSM operators around the world are upgrading their networks, with a view to launching commercial GPRS services in 2000. UMTS services will launch commercially from 2002.

Third Generation Mobile Communications System (3G)

• The fundamental purpose of the Third Generation Mobile Communications System is to provide a globally integrated communication system consisting of different, today incompatible, network technologies that are deployed around the world. All those second generation communications systems and mobile terminals will, eventually, evolve towards a global standard, which is called IMT-2000 (International Mobile Telecommunications).
• IMT-2000 specifies the technologies, standards and protocols to be used worldwide by 3G technologies. IMT-2000 is an initiative of the ITU (International Telecommunication Union) to provide wireless access to the global telecommunication infrastructure through both satellite and terrestrial systems, serving fixed and mobile users in public and private networks.
• In Europe, the third generation mobile system is called Universal Mobile Telecommunications System (UMTS). It is currently under specification in ETSI and it is intended to be completed by the end of 1999. UMTS will deliver low-cost, high-capacity mobile communications offering data rates up to 2 Mbit/s with global roaming and other advanced capabilities. UMTS will deliver pictures, graphics, video communications and other wide-band information as well as voice and data, directly to people who can be on the move. WCDMA radio access technology is used in UMTS. UMTS licenses have already been awarded in several European countries.
• In Japan, the standardisation organisations ARIB (radio) and TTC (network) are preparing third generation standards. The target for the first networks is in 2001. In the United States, there are three second generation standards (IS-136, IS-95 and GSM 1900) widely deployed. They will all evolve towards IMT-2000. [15]
• The most extensive co-operation project will be the Third Generation Partnership Project (3GPP). This co-operation between international standards bodies will make the third generation mobile telephony happen. The founding members are ARIB and TTC of Japan, ETSI of Europe, T1 (ANSI) of the U.S. and TTA of Korea. The work of these organisations will be promulgated globally by the ITU as IMT-2000. UMTS is one "family member" of IMT-2000.
• There are many problems in developing an integrated global communications system, not only technical issues but also various political dilemmas. There will be different systems in use also in the future but the development of mobile terminal technology will partly solve this problem.

Wideband Code Division Multiple Access (WCDMA)

• WCDMA is a totally new radio access technology which is not anymore based on GSM radio frequency but brings a completely new modulation method. It can provide a high capacity radio interface to the GSM core network, though. WCDMA will provide access at up to 2 Mbit/s in the local area and less than 1 Mbit/s wide area access with full mobility. These higher data rates require a wide radio frequency band, which is why a WCDMA with 5MHz carrier has been selected. This corresponds to the 200 kHz carrier for GSM.

Enhanced Data Rates for GSM Evolution (EDGE)

• EDGE, a new radio interface technology with enhanced modulation increases the HSCSD and GPRS bit rates by up to three folds. EDGE air interface channel coding offers approximately 48 kbit/s per air interface traffic channel. Consequently Enhanced GPRS (EGRPS), as it is referred to, offers theoretically 384 kbit/s bit rate by using all eight air interface time slots.

General Packet Radio Service (GPRS)

• GPRS provides mobile subscribers with packet switched connection to packet data networks, like the Internet or corporate networks. GPRS will offer a tenfold increase in data throughput rates, from 9.6 kbit/s to 115 kbit/s. The maximum bit rate, theoretically, is 171.2 kbit/s which is achieved using 8 air interface time slots simultaneously. In GPRS, a separate IP backbone network will be introduced which acts as an interface between GSM and packet data networks, like the Internet.

High Speed Circuit Switched Data (HSCSD)

• HSCSD is a circuit switched connection over a standard GSM network. The channel speed of HSCSD is 14.4 kbit/s and it provides a possibility to use multiple time slots for the data transmission. The first commercial HSCSD mobile stations will be capable to use up to four time slots simultaneously.

GSM Radio Technology Evolution Path

• The new mobile datacom services will differ from the second generation GSM data services in several ways. Perhaps the most essential changes take place in the radio access technology. For example, they support much higher bit rates over the air interface, which is basically made possible by more efficient channel coding and the ability to use multiple time slots. In addition, General Packet Radio Service (GPRS) will bring packet switched communication to GSM. The following chapters describe the GSM Radio Technology evolution steps.

Future Mobile Data Communications Services

• As mentioned in the previous section, the air interface is the bottleneck when transmitting data between a mobile station and a data network using the current mobile services. A major part of the evolution of mobile data communications services is dependent on the evolution of the GSM.
• GSM radio access technology has a clear evolution path and, eventually, it will provide a bandwidth wide enough for various kinds of services. Hence, GSM radio technology will remain an essential access network well into the next century.

Introduction

• Today, the cellular networks are evolving to meet the new requirements of mobile data communications. The target of the mobile communications system development is to create service that is able to offer global coverage with multi-media access speed. Today, satisfactory mobile data communications are possible only via a second generation digital mobile communications network. The world's most advanced and wide spread second generation mobile network is GSM (Global System for Mobile Communications).
• There are two methods how data can be transferred in GSM: Short Message Service (SMS) and GSM data service. Both of them enable 9.6 kbit/s circuit switched connection. However, data transmission capabilities of SMS are much more restricted and thus it is only suitable for transmitting short text messages.
• There are several drawbacks in the second generation GSM being a bearer service for data. For example, the bit rate of the GSM radio access network is very low, thus clearly acting as a bottleneck in the end-to-end system. In addition, a relatively long connection setup time and the typical restrictions of a circuit switched connection method in data transmission limit data applications to be offered.

History of cellular Communications

• In a separate segment of communications, another revolution was taking place—cellular telephones. In the late 1970s AT&T Bell Laboratories began working with several leading United States and Japanese companies to create a cellular telephone system based on dividing coverage areas into small cells and reusing frequencies. Previous mobile telephone technologies operated on limited numbers of channels, thus limiting the number of users in any given coverage area to a very small number.
  
• The result was low user use and costly service and equipment. A core group was created to develop a standard called the Advanced Mobile Phone Service (AMPS). In December 1983, AMPS was launched in Chicago, Illinois with great fanfare. It proved immensely popular. Now before someone says, “Hey, wait a minute, AMPS wasn’t the first cellular system!,” let’s give that credit to the Nordic Mobile Telephone (NMT) system.
  
• NMT was launched in 1981 in Scandinavia, but in terms of market size, AMPS potential market in the United States was vastly larger. AMPS quickly spread to other countries in North and South America, Korea, and Australia. A similar standard, Total Access Communications System (TACS), was developed in the United Kingdom as well.
• Today, there are many competing standards in mobile telephones worldwide. In fact the word “mobile” means something entirely different today than it did in 1983. The majority of cellular telephones sold today are hand-held, not permanently installed in vehicles. Each competing standard is incompatible with others on the basic technology used, but to the end user, all cellular telephones should perform the basic functions expected. (Even though many new carriers would like to distinguish themselves from “cellular” companies by calling themselves “PCS” companies, we consider both as cellular applications.
• This is not to say that companies with PCS spectrum in the 1900 MHz band may or may not have some advantages over carriers with traditional spectrum allocations in the 800 MHz band. But because many carriers own spectrum in both bands this is a moot point.)
• Cellular radio got its name from the physical layout of a system in a pattern resembling a honeycomb figuratively. Each cell site operates on a different frequency so that neighboring cells do not interfere with one another. However, frequencies can be re-used if they are separate by sufficient distance. This is referred to as the re-use pattern.