Chapter: Network Concepts and Standards
The concept of a small, light weight and convenient pocket communicator is a fundamental part of IMT-2000, and providesterminal mobility, which is complementary to the personal mobility and service profile management provided by Universal Personal Telecommunication (UPT).
A number of different radio environments are involved, including not only very small indoor cells with high capacity, but also large outdoor terrestrial cells or even satellite coverage. A major focus of the ITU-R standards work on IMT-2000 is to maximize the commonality between the various radio interfaces involved in order to simplify the task of building multi-mode mobile terminals covering more than one operating environment.
Initial studies were aimed at defining the objectives for IMT-2000 and the resulting spectrum requirements as part of the ITU-R input to the World Administrative Radio Conference in February 1992 (WARC92). WARC-92 identified the bands 1 885 - 2 025 and 2 110 - 2 200 MHz, on a global basis for IMT-2000 including the bands 1 980 - 2 010 and 2 170 - 2 200 MHz for the satellite component of IMT-2000 (see ITU Radio Regulations provision no. 746A).
An important aspect of the ITU-R studies on IMT-2000 is the potential for these new mobile radio technologies to provide cost effective and flexible access to the global telecommunications networks in developing countries and under-developed parts of developed countries. Currently a number of digital mobile telecommunication systems have been standardized in some regions and more are planned to be defined in the near future. These are often referred to as "second generation" systems. They include various paging, cordless, cellular, mobile data and mobile satellite systems.
IMT-2000 is a third generation system which aim to unify the diverse systems we see today into a radio infrastructure capable of offering a wide range of services around the year 2000 in many different operating environments.
The decisions at WARC-92 most relevant to IMT-2000 were the identification of global spectrum with both satellite and terrestrial parts in a common band. These set the scene for a IMT-2000 standard capable of providing a much wider range of services than those that are available today, and with the quality we know from the fixed (i.e., wireline) telecommunications networks.
IMT-2000 aims at highly cost effective radio access networks, particularly for developing countries, whether they require the associated mobility management capabilities or not. The modular nature of IMT-2000 allows networks to be configured with just the capabilities required and then enhanced if required to a fully personalized mobile network. The dual transmission capabilities (satellite and terrestrial), allow initial deployment via satellite, where there is little or no existing fixed infrastructure, and migration to a terrestrial infrastructure later on.
Candidates for IMT-2000 are
Key features of the radio access for IMT-2000 therefore include:
The world wide frequency bands 1980 - 2010 and 2170 - 2200MHz were scheduled by WARC-92 to be available for the Mobile Satellite Service in 2005. These bands are intended to accommodate the satellite component of IMT-2000, but would need to be available around the year 2000 to allow the introduction of the satellite component at the same time as the terrestrial component.
The different service aspects and service environments for IMT-2000, and the importance of making the best use possible of the limited radio spectrum, call for a very flexible solution to the radio interface and its interworking with the transmission technology used in the fixed networks (e.g. "resource on demand" in a dynamic way, within fractions of a second). Broadband ISDN (BISDN) technologies will also be in an advanced stage when IMT-2000 are introduced. Therefore, BISDN access and interworking and the flexibility of Asynchronous Transfer Mode (ATM) transmission technology are taken into account and efficient interworking with ATM will be defined. IMT-2000 also needs to be interconnected to many earlier analogue and digital fixed networks.
IMT-2000 is specified so that services can be provided by a stand alone network with gateway connections to the fixed networks, including Public Switched Telephone Network (PSTN), Integrated Services Digital Network (ISDN), Packet Switched Public Data Network (PSPDN), as well as existing Public Land Mobile Networks (PLMN). But it is equally possible to implement IMT-2000 functionalities as an integral part of the nodes of the fixed network. The stand alone option is important in a multi-operator environment. The integrated option is important for fixed network operators that want to integrate radio access, where permitted, as a natural part of the fixed network. Radio access as defined for IMT-2000 is expected to be an economic alternative to wired local loops and is therefore of special interest to developing countries.
Network management is another important area for IMT-2000 to achieve considerable operational cost reduction. IMT-2000 will include a variety of functions such as planning, installation, provisioning, operation, maintenance, administration and customer services in a multi-vendor and multi-operator environment. To provide these functions, the concept of a Telecommunications Management Network (TMN), which is being studied by ITU-T, is employed in IMT-2000. This makes IMT-2000 cost-efficient and suitable for multi-operator environments.
Section contributed by Serguei V. Valov, RILRDT, Saint-PetersburgThis section presents SoftWare Radio (SWR) as a key technology concept towards IMT-2000. There are three features in the IMT-2000 concept which make the SWR concept necessary, on the one hand, and feasible, on the other one, namely:
Such features are hardly feasible without SWR technologies, whereas, in turn, the concept paves the way for the SWR's feasibility within IMT-2000.
Apparently, the most profits and benefits from the SWR inside IMT-2000 could be expected by vendors and operators. The SWR technologies will allow to safe money with hardware development and deployment for both of the parties while the wireless communications progress continues.
At the same time, not every terminal and handset will be implemented with a SWR technology and the SWR user equipment will be palpably more expensive than a user equipment based on the traditional hardware technology. Thus, the more SWR functionality, the more expensive yet the more multiple-functional witll be the subscriber's choise. Now, subscribers will get a unique opportunity to make tradeoff between the price of services and their variety by means of buying a more or less expensive terminal or handset. In contrast to conventional solutions, they buy only one handset.
There is a special page, describing the concept of Software Radios (SWR), and their basic architecture.