IMT frequency bands
IMT Studies in Europe
IMT Studies in Japan
3G Partnership Project (3GPP)
UMTS Release 99
CDMA2000
3G Partnership Project 2 (3GPP2)
1x Radio Transmission Technology (1x RTT)
CDMA2000 Evolution 1XRTT EV DO
The holy war of wireless
Final IMT-2000 Standards

Specification of Third Generation Mobile Communication

As early as the late 1980s, it became clear that various second-generation digital standards would emerge around the world. However, it was of global importance that uniform and progressive standards had to be achieved for the next generation of mobile communications systems, which were expected at the turn of the millennium. Therefore, a study was started by the ITU (International Telecommunication Union) to define the requirements for a next-generation system. The new system was called IMT-2000, International Mobile Telecommunications for the year 2000.

Future public land and mobile telecommunication system

The study had the strange title FPLMTS (Future Public Land and Mobile Telecommunication System). The following requirements emerged from this study:

• Frequency range around 2000 MHz
• Worldwide application/validity of the standards
• Suitable for voice, multimedia and Internet
• Supports circuit switching and packed switching
• High data rates up to 2 Mbit/s
  – 144 kbit/s for mobile applications
  – 384 kbit/s for stationary applications
  – 2 Mbit/s for offices
• High spectral efficiency

The goals turned out to be ambitious. Above all, the desire for an international standard worldwide with roaming could not be achieved.

As early as 1992, it became apparent that there would be four “families” of IMT-2000 standards:

• Wideband CDMA (W-CDMA): A CDMA based system like IS-95 CDMAOne but with a significantly higher bandwidth to achieve higher bit rates.
• TD-CDMA: Also a CDMA based system, which however does not use duplex channels but shares a single channel in time division multiplex.
• TDMA: Further developments of the 2G TDMA systems (later realized through EDGE)
• FD-TDMA: Further development of the European DECT standard for cordless telephones.

By the 1990s, the world had already decided into several global camps. Europe had developed the GSM system and successfully tried to spread it worldwide. For Europe and for the GSM camp it was important that IMT-2000 was not a revolution but an evolution.

In the USA, CDMAOne (IS95) was established by Qualcomm. This company was pushing for an evolution that would be backwards compatible with IS-95. A “union” with the GSM camp seemed hopeless.

In Japan and Korea people were more willing to create a revolution. Japan in particular developed into a leading nation in mobile communications, even if their standards were more of a national nature. They pushed for innovation.

IMT Frequency Bands

As early as 1992, the ITU-R proposed several frequency bands around 2 MHz for the use of IMTS-2000.
1885 MHz to 2025 MHz: Lower band 140 MHz wide
as well as
2110 to 2200 MHz: Upper band 90 MHz wide

These two bands should be used for both frequency division duplex FDD (upper and lower bands) and time division multiplex TDD (transmitter and receiver share a common band).

For satellite-based IMTS-2000 systems, the upper and lower bands 30 MHz were reserved, which are not available for terrestrial use.

In Europe it was decided to reserve the frequency range from 1880 MHz to 1900 MHz for the DECT (Digital European Cordless Telecommunication) standard. Two blocks of 20 MHz each were reserved for TDD CDMA.

IMT 2000 Studies in Europe

Multiple independent projects started after the definition of the requirement to define suitable standards. As mentioned, a separate standardization institute was founded in Europe in 1988: European Telecommunications Standards Institute (ETSI). Just one year later, ETSI started a project for a third-generation mobile communications system called RACE 1 (Research, Analysis, Communication, Evaluation), which carried out basic development until 1992. The focus soon became on Wideband CDMA (W-CDMA) as the basic family. W-CDMA is a CDMA system with a bandwidth of 5 MHz, 4 times as wide as CDMAOne IS-95.

Research into 3G technologies was already being carried out in Europe at the beginning of the 1990s

A follow-up project called RACE 2 followed in which concrete concept studies for W-CDMA were carried out in order to meet the IMT-2000 requirements.

In the mid-1990s, ETSI gave its more concrete proposal a name: Universal Mobile Telecommunication System (UMTS). In 1996, an organization called the UMTS Forum was founded to further focus on this standard.

IMT 2000 Studies in Japan

The Japanese standardization organization ARIB (Association of Radio Industries and Businesses) started its first projects in 1993 to develop systems for IMTS-2000. A „Radio Transmission Special Group“ was created. Initially, people looked at CDMA and TDMA systems with an open mind. However, the focus soon fell on W-CDMA. In 1996, the world’s largest mobile phone provider NTT Docomo decided to conduct a field trials with W-CDMA. This gave a huge push to all ongoing developments, including those in Europe. In 1998, W-CDMA was officially submitted as a standard proposal to the ITU-R.

The 3G Partnership Project, 3GPP

Due to the Japanese push for W-CDMA, this standard was also adopted for the European UMTS system in 1998 and thus became part of the UMTS standard.

Now, through W-CDMA, Europe had common ground with Japan and also with developments in the USA beyond the CDMA Development Group of IS-95. It therefore made sense to create a joint global organization that would further advance the 3G standard. The 3G Partnership Project (3GPP) was founded in December 1998. The largest standardization organizations were united here:

• ARIB (Japan)
• ETSI (Europa)
• ATIS (USA)
• TTA (Korea)
• TTC (Japan)

The Association of Radio Industries and Businesses is a Japanese Radio Standardization Group. The Alliance for Telecommunications Industry Solutions (ATIS) is an American standards group for Information Communications Technology (ICT). The Japanese Telecommunication Technology Committee (TTC) is a standardization authority. The Telecommunications Technology Association (TTA) in Korea is a private standards organization.

3GPP meets regularly in changing global locations and defines all new mobile communications standards. Standardization organizations from China and India joined later.

UMTS Release 99

One year after the founding of the 3GPP, the first UMTS standard was published by ETSI. It contained the exact specification of the new W-CDMA based mobile radio system. Since it was released in 1999, it was called Release 99. Now 3G devices could be developed. However, it took another three years until the first UMTS networks went into operation in Europe in 2002.

CDMA2000

The CDMA Development Group (CDG) around Qualcomm was looking for its own candidate for IMT-2000. However, this should be backwards compatible with IS-95. As described, IS-95 became an official standard in 1995. This was improved two years later, primarily to achieve better data transmission performance. IS-95 Rev B was released in 1997, which allowed a data transfer rate of 64 kbit/s and thus offered the first reasonable access for mobile Internet, comparable to GPRS.

The next generation of CDMA should then meet the IMT-2000 requirements. The CDG named this system CDMA2000.

3G PARTNERSHIP PROJECT 2 (3GPP2)

Driven by the progress of W-CDMA in Asia and Europe, CDMA2000 also tried to organize itself globally. A 3G Partnership Project (3GPP2) was also founded in 1998, which was intended to focus on CDMA2000. Founding members were:

• TIA (USA)
• ARIB (Japan) 
• TTC (Japan)
• TTA (Korea)

Thus, Japan and Korea participated in both standardization programs. This was particularly to be expected in Korea, because SK Telecom there was already using CDMAOne in 1996.

1X RADIO TRANSMISSION TECHNOLOGY (1X RTT)

To maintain compatibility with IS-95, CDMA2000 remained at a bandwidth of 1.25 MHz. For later higher bit rates, expansions of 3, 5, 7, etc. times the bandwidth were planned. So the first CDMA2000 standard was called 1X because it had the same bandwidth. More specifically 1X RTT (Radio Transmission Technology).

With CDMA2000 1XRTT, IS-95 has been expanded to include packet switching. So this first step was actually more of a 2G standard (2.5 G) and corresponded to/followed the GPRS/EDGE development to improve mobile internet. A bit rate of up to 144 kbit/s could be achieved. Like EDGE, CDMA2000 1XRTT already met the criteria of IMTS-2000 and was submitted to the ITU in 1999 as a candidate for IMT-2000.

The improvements were achieved primarily through 4 measures:

• 128 bit Walshcode Spreading
• Introduction of Turbocodes (to replace convolutional channel coding)
• Increase of the spectral efficiency through I/Q Modulation
• Improvement of the modulation through Orthogonal Complex Quadrature Phase Shift Keying

Some of the improvements will be discussed elsewhere.

CDMA2000 EVOLUTION 1XRTT EV DO

The first actual 3G standard from CDMA2000 was called 1xRTT EV DO. EV like Evolution and DO like Data Optimized. DO also means Data Only and thus indicates that this transmission standard was intended exclusively for data transmission and not for voice. Data rates of 3.1 Mbit/s in the downlink and 1.8 Mbit/s in the uplink were achieved.

1xRTT EV DO was released in 2000 and first introduced in Korea in 2002.

The Holy War of Wireless

CDMA was not an invention of Qualcomm. CDMA was a technology that was developed in the 1970s primarily for military applications. It wasn’t Qualcomm’s sole idea that CDMA could be used for mobile communications. Since the IMT-2000 initiative, many research institutions have been looking into the possibility of using CDMA as an efficient transmission technology since the late 1980s. Above all, companies like Ericsson.

However, Qualcomm was the first company to make CDMA a standard and the first to bring it to market. And most important, CDMA went through real life field trials and learned a lot from it. This brought Qualcomm in a leading position and gave him the possibility to develop essential patents related to CDMA. But Ericsson now also had a considerable CDMA patent portfolio and both companies were competing with each other. When IS-95 was released as a standard in 1995, Ericsson sued Qualcomm for violating key patents surrounding CDMA. Qualcomm fought back vigorously and over time sued Ericsson for violating their CDMA patents as Ericsson was openly working on W-CDMA for IMT-2000.

The dispute became more and more political as Ericsson worked primarily on the European UMTS standard and W-CDMA while Qualcomm relied on the established IS-95 standard and its evolution. Qualcomm managed to establish itself in South America, Korea and even China, but not in Europe. Finding itself excluded, Qualcomm contacted the US State Department to complain that the European Union was requiring its members to license only W-CDMA/UMTS. In fact, in 1998, this led the Foreign Ministry (under Madeleine Albreight) to turn to European politician Martin Bangemann, who was responsible for communications in the EU.

The EU was accused of violating WTO rules by specifying which technology should be used in third-generation mobile communications. Bangemann replied that there was no such request, but only a recommendation to the countries to choose a standard proposed by the ETSI. He explained that standardization was a matter for the communications industry and that the EU would not influence technical decisions. He also recommended that efforts should be made to ensure that Ericsson and Qualcomm in particular come to an agreement.

Qualcomm and the US accused Europe to protect the European telecom market against American standards and companies.

In fact, time was of the essence. In 1999 the ITU wanted to set the IMT-2000 standards. However, this made no sense as long as there were no agreements on patent licensing. A deadline was set to end the legal dispute by the end of March 1999. Qualcomm and Ericsson fought in a Texas court until February.

In the end, a deal was struck in March 1999. There was a cross-license for the CDMA standards and Ericsson took over Qualcomm’s IS-95 infrastructure division. This enabled Ericsson to be active in infrastructure equipment in all mobile communications markets. The way was clear for 3G for mobile communications.

Final IMT-2000 Standards

In 1999, five candidates for IMT-2000 were finally standardized by the ITU-R:

• IMT-2000 CDMA Direct Spread
  This is W-CDMA according to ETSI/3GPP proposal. It was therefore backwards compatible with GSM.
• IMT-2000 CDMA Multi-Carrier
  This was CDMA2000 according to Qualcomm 3GPP2. It was backwards compatible with IS-95.
• IMT-2000 CDMA TDD
  This is the single carrier solution based on W-CDMA with timeslots for the time multiplex. This was part of 3GPP UMTS Standard
• IMT-2000 TDMA single Carrier
  This is the well known 2.5 G GSM system EDGE and therefore backward compatible to GSM
• IMT-2000 FDMA/TSMA
  This is the European DECT (digital European cordless telephone) Standard and its evolution.

The ITU’s original goal of achieving a uniform 3G standard had not been fulfilled. Instead of one standard, there were five standards, with UMTS and CDMA2000 being significantly different. The standards had been set but had not yet been tested in a real network. All this were dark skies for the subsequent ramp-up of the 3G networks.