3GPP’s Evolutional Path to 4G
The third-generation (3G) mobile networks have been deployed in many countries in the world.
However, even before its deployment, its enhancement activity had already started and has been
actively pursued in the Third Generation Partnership Project (3GPP) [810, 811, 816]. Furthermore,
in various fora and organizations for wireless research, such as International Telecommunication
Union (ITU) [813] and the Wireless World Research Forum (WWRF) [812], there have been active
discussions about 4G systems, which have been targeted for deployment around 2010. Intensive
research and development activities have been carried out in both academia and industry around the
world.
These R&D activities are quite appropriate if we recall that research in 3G systems began more
than 10 years ago, and take a look at the explosive growth of the mobile/wireless communication
market in these 10 years. According to the statistic given in [813], the number of mobile subscribers
worldwide increased from 300 million in 1997 to about 1200 million in 2005. Based on this estimated
growth trend, it is predicted that by 2010 there will be about 1800 million subscribers worldwide.
Therefore, it is considered a timely strategy to start the R&D a couple of years before the 4G wireless
is expected to be ready in or around 2010. A vision for 4G wireless communications in terms of
mobility support and data transmission rate is shown in Figure 10.1.
In this chapter, we are going to focus on the R&D activities for 4G wireless communications
carried out under the 3GPP, which is an international organization responsible for the development
and harmonization of the UMTS UTRA series standards (such as the WCDMA standard and the
TD-SCDMA standard, etc.), as discussed in Sections 3.2 and 3.3.
As discussed in Section 3.2, it is noted that High Speed Downlink Packet Access (HSDPA), as an
extension of the UMTS 3G system, can already offer a data rate up to 10 Mbps on a downlink (DL)
channel. HSDPA is an enhanced 3GPP-3G standard to increase the DL throughput by replacing QPSK
in UMTS 3G by 16QAM in HSDPA. It works to offer a combination of channel bundling (TDMA),
code division multiplex (CDM) and improved coding adaptive modulation and coding (AMC). It also
introduces a separate control channel to facilitate the data transmission speed. Similar techniques will
also be used in the uplink (UL) to yield High Speed Uplink Packet Access (HSUPA) standard. In
order to make 3GPP UTRA/UTRAN technology even more competitive in the world, and chiefly to
compete with the new technologies proposed by 3GPP2, 3GPP decided to go for an Evolved UTRA
and UTRAN (also called Super-3G standard), which will work for the next 10 years and beyond, as
a long-term evolution of the 3GPP radio-access technology. It has to be noted that, due to the limitations of space in this book, we will not discuss the 4G
R&D activities carried out by 3GPP2 in parallel to these discussions; 3GPP2 being the other camp
formed under the umbrella of CDMA2000 series standards, as discussed in Section 3.1.
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