ASIA-PACIFIC BROADCASTING

IMT-2000 and IMT-Advanced Standards
The ITU has clarified the terms IMT, IMT-2000 and IMT-Advanced as follows:
1)the term “IMT-2000” encompasses also its enhancements and future developments;
2)the term “IMT-Advanced” is applied to those systems, system components, and related aspects that include new radio interface(s) that support the new capabilities of systems beyond IMT-2000;
3)the term “IMT” is the root name that encompasses both IMT-2000 and IMT-Advanced collectively.

The next cellular network evolution will be from 3G to 4G although some operators are now deploying what they call 3.5G networks.  The main characteristics of 3G and 4G networks are:

IMT-2000 technologies are often described as 3G technologies and IMT-Advanced technologies (still to be developed) as 4G technologies.  The mobile WiMAX 802.16e Standard is often described as a 4G network since it has all the characteristics of 4G networks except the speed.  However, since the criteria that constitute a 4G network have not yet been defined it is more appropriate to speak of mobile WiMAX 802.16e Standard as a pre-4G standard.

IMT-2000
The designation of IMT-2000 was developed within the ITU as an attempt to develop one standard for third generation (3G) systems for mobile communications.  However, in spite of what is stated on the ITU site web, it was not possible to agree on one standard.  Therefore, all standards with enough support were included in the IMT-2000 designation. 

Prior to the inclusion of mobile WiMAX (802.16e) in the IMT-2000 standards as defined by ITU Rec. M.1457-6, IMT-2000 supported five radio interfaces and three different access technologies, using CDMA, TDMA, and FDMA.

Figure 1 shows the five families of standards of IMT-2000 before the inclusion of WiMAX.



 Figure from ITU web site for IMT-2000, IMT-2000, “International Mobile Telecommunications”

Fight between 3G and WiMAX
Mobile WiMAX could be a disruptive technology as far as the incumbent cellular network operators are concerned.  New entrants not burdened with having to support legacy equipment could establish national networks and potentially offer mobile voice and data services at lower prices.  One way in which the 3G operators had tried to keep mobile WiMAX from offering service was by having spectrum designated in the ITU Table of Frequency Allocations for use by IMT-2000 (3G) technologies which support legacy networks.  WiMAX is a pre-4G standard and does not support circuit switched networks. However, the fight ended with victory of the WiMAX lobby when the mobile version of WiMAX was included into the IMT-2000 family of standards as specified in Recommendation ITU-R M.1457 (“Detailed specifications of the radio interfaces of International Mobile Telecommunications-2000 (IMT-2000”).


IMT-Advanced
IMT-Advanced was previously known as “systems beyond IMT-2000”.   Again, the ITU has set up working groups to standardize 4G.  The full criteria being developed within ITU-R Working Party 8F are not expected until 2008 but they include target peak data rates of up to 100 Mbits/sec in high mobility applications and up to 1 Gbit/sec in low mobility or nomadic applications. The capability proposed by IMT-Advanced is often referred to as “4G.”  It is expected that the specification of IMT-Advanced technologies will not be completed until 2010.  The IEEE 802.16 (WiMAX) Working Group has initiated a new project designated as “802.16m”.  The objective is to develop an IEEE 802.16 Standard compatible with IMT-Advanced.

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