3G Network

3G services work together with existing ones

Today's mobile networks were originally optimized for voice traffic. To carry large amounts of data traffic quickly and cost-effectively improved radio interfaces will be needed, capable of providing higher-bandwidth connections to more users simulateously­ Wideband radio technology has been optimized for multimedia services and high-speed Internet access. It will also be very spectrum-efficient, helping make the most of available spectrum. Radio access for 3G will be provided in two ways: the addition of new wideband radio technology to make use of newly available radio spectrum; and the evolution of current radio technology to provide higher-speed capabilities. The International Telecommunications Union (ITU) recommendations for the IMT­2000 standard for next-generation services, a data rate of 2Mbit/s indoors is envisaged. In the wide-area environment - on suburban streets, on the train or in the car, for example - IMT-2000 envisages a data rate of up to 384kbit/s.

Multi-band, multi-mode phones have already shown how innovative terminal design can make the frequency of the radio access an irrelevance for users of mobile set­vices. In the same way, "2G/3G-capable" dual-mode phones will provide transparent access to services delivered over different radio networks. 3G coverage can be built out in line with market demand - as an overlay network, for example.

What is the effect of 3G?

Implementing 3G does not just mean standardizing a new radio interface. New techniques and evolution strategies for delivering 3G are needed for all levels of the network.

When the current mobile standards were developed, they were generally applied right across the network. A GSM network is GSM at the handset, radio communications and core network levels. Much the same goes for TDMA (ANSI-136 digital mobile standard) and cdmaOne (ANSI-95, a CDMA-based digital mobile standard). In the case of 3G, a different approach is being taken. There is one standardization process for the radio network and another for the core network. That is why, when the industry talks about 3G wideband Radio Transmission Technologies (RTTs), it is only the radio communications part of the network that is being discussed. The core network is being developed and standardized in parallel, and in many cases will be an evolution of today's core networks. There will be a core network that has transport "pipes" for information flow, nodes that route the traffic, and nodes where the services are located. The core network will also have connections to other wired and mobile networks, to provide interconnectivity with the global telecoms networks. Connected to this core network will be the mobile radio network, providing the wideband interface for users.

Strategies for migration to these 3G capabilities from today's GSM, cdmaOne and TDMA networks envisage that evolved and new wideband radio networks will be able to share a common core network. History and commercial reality dictate that 3G will need to be provided across a wide range of radio frequencies and techniques, switching platforms and transmission technologies. Once standards have been agreed, the focus will be on the services and applications rather than the technologies used to deliver them.

How will 3G standards look?

There will be a "family of standards" for 3G, covering new Radio Transmission Technology (RU).

A number of proposals for the IMT-2000 3G standard were submitted to the ITU during 1998. Since this time, the industry and standards bodies have coordinated their efforts to harmonize the IMT-2000 candidates and arrive at a smaller set of standards. The Operators Harmonization Group (OHG) - a group of major operators from all parts of the world - has played a key role in this process, and agreed on a set of standards in May 1999.

The chart shows a standardized evolution path for mobile wireless system from 2G to 3G.

This family of standards includes one GDMA-based standard with three optional modes Multi-Carrier (Mc) Direct Spread (DS) and Time Division Duplex (TDD) and one TDMA hased standard (EDGE). The radio standards can he combined with different core network standards (GSM MAP or ANSI-41) and operate in different frequency hands. The Multi-Carrier (Mc) mode is also called cdma2000 Mc; and the Direct Spread (DS) Mode is also called WCDMA. The UMTS standard covers WCDMA, TDD and GSM/MAP.

Where is the new radio spectrum?

International standards and regulatory bodies have set aside radio frequency in the 2GHz band.

In 1992, the World Administrative Radio Conference (WARC) allocated 230MHZ of new radio spectrum to terrestrial and satellite services. Of this, the ITU has set aside 155MHZ in the 2GHZ band for terrestrial 3G services, as shown in the chart. Spectrum has been allocated in Europe and Japan in two 2GHZ bands, close to those recommended by the ITU, to meet these requirements. In the USA, much of the lower 2GHZ band allocated for IMT-2000 at WARC has been consumed by PCS spectrum allocations.

The Radio Frequency Spectrum