3G and Its Releases

The 3G will provide mobile multimedia, personal services, the convergence of
digitalization, mobility, the Internet, and new technologies based on the global
standards [5–7, 11]. The end user will be able to access the mobile Internet at
the bandwidth (on demand) from 64 Kbps to about 2 Mbps. From a business
perspective, it is the business opportunity of the twenty-first century.
The international standardization activities for 3G is mainly concentrated
in the different regions in the European Telecommunications Standards
Institute (ETSI) Special Mobile Group (SMG) in Europe, Research Institute of
Telecommunications Transmission (RITT) in China, Association of Radio
Industry and Businesses (ARIB) and Telecommunication Technology Committee
(TTC) in Japan, Telecommunications Technologies Association (TTA) in
Korea, and Telecommunications Industry Association (TIA) and T1P1 in the
United States.
Details of all proposals for IMT-2000 are available in [12]. The international
consensus building and harmonization activities between different
regions and bodies are currently ongoing. A harmonization would lead to a
quasi-world standard, which would allow economic advantages for customers,
network operators, and manufacturers. Therefore, two international
bodies have been established: 3GPP and 3GPP2.
The 3GPP was established to harmonize and standardize in detail the
similar ETSI, ARIB, TTC, TTA, T1 WCDMA, and related TDD proposals
[13–15]. The 3GPP decided to base its evolution to an IP core network on
GPRS. The GPRS–based approach provides packet data access in 3GPP.
The 3G.IP forum initiated the early work on an all IP-network in early 1999,
but all the work has since been moved to the 3GPP [13]. The UMTS network
architecture is an evolution of the GSM/GPRS. The network consists
of three subnetworks: UMTS terrestrial radio access network (UTRAN),
circuit-switched (CS) domain, and packet-switched (PS) domain.
The UTRAN consists of a set of radio network subsystems (RNSs) connected
to the core network (CN) through the Iu interface. If the CN is split
into separate domains for circuit- and packet-switched core networks, then
there is one Iu interface to the circuit-switched CN (Iu-CS) and one Iu interface
to the packet-switched CN (Iu-PS) for that RNS, as shown in Figure 2.2.
An RNS consists of a radio network controller (RNC) and one or more
node Bs. A node B is connected to the RNC through the Iub interface.
Inside the UTRAN, the RNCs in the RNSs can be interconnected together
through the Iur interface. The Iu and Iur are logical interfaces, which may be
provided via any suitable transport network. A node B can support one or more radio cells. A node B may support
user equipment (UE) based on FDD, TDD, or dual-mode operation. During
macro diversity (soft handover), a UE may be connected to a number of
radio cells of different node Bs or RNSs. Each RNS is responsible for the
resources of its set of radio cells and for handover decisions. The controlling
part of each RNC (CRNC) is responsible for the control of resources allocated
within node Bs connected to that RNC. For each connection between
a UE and the UTRAN, one RNC is the serving RNC. When required, drift
RNSs support the serving RNC by providing radio resources within radio
cells connected to that drift RNC. Combining/splitting for soft handover
may be supported within node B, drift RNC, or serving RNC. Softer handover
provides better performance but is only possible within node B, between
radio cells connected to that node B.
Any RNC can take on the role of serving RNC or drift RNC, on a
per-connection basis for a UE. This supports macro diversity (soft handover)
when the UE roams into another RNS. Eventually a relocation process (separate
from handover) may be used to reroute the Iu connection to the new
RNS, after which the drift RNC becomes the serving RNC for the UE.
Radio access bearers (RABs) are provided between the UE and CN (via the Uu
radio interface, UTRAN internal interfaces, and Iu interface) for the transport
of user data. Control plane protocols provide the control of these RABs
and the connection between the UE and the network. Control plane protocols
over Uu would be carried between radio resource control (RRC) entities
in the UE and UTRAN. During 2000, 3G was split by 3GPP (see Table 2.1) into two releases:
R99 and R2000. R99, also known as Release 3, of the UMTS system supports
WCDMA access and ATM-based transport. UMTS R00, split into
two releases (Release 4 and Release 5 [13]), defines two radio access network
(RAN) technologies, a GPRS/EDGE radio access network (GERAN) and a
wideband CDMA RAN (R3 UTRAN). Both types of RANs connect to the
same packet-switched CN (an evolution of the GPRS network) over an Iu
interface. One main objective of UMTS R00 is to have the option of all-IPbased
CN architecture, thus setting the tone for UMTS standardization in
2000 and beyond. Benefits expected from this approach include the ability to
offer seamless services through the use of IP, regardless of means of access,
simultaneous multimedia services, and rapid service deployment, in addition
to synergy with generic IP developments and reduced cost of service. However,
the all-IP architecture in UMTS R00 (Releases 4 and 5) must support
the services and capabilities of R99, R00, and beyond. It must ensure an evolution
path with sufficient backward compatibility.
The 3GPP2 [9] was also established for the CDMA2000-based proposals
from TIA and TTA. Technical specification work for CDMA2000 standardization
is being done within 3GPP2 in the following steps:
• CDMA2000 1x, which is an evolution of cdmaOne, supports
packet data service up to 144 Kbps.• CDMA2000 single carrier evolution-data only (1xEV-DO) introduces
a new air interface and supports high-data-rate service on
downlink. It is also known as high-rate packet data (HRPD). The
specifications were completed in 2001. It requires a separate 1.25-
MHz carrier for data only. The 1xEV-DO provides up to 2.4 Mbps
on the downlink, but only 153 Kbps on the uplink.
• CDMA2000 single carrier evolution and voice (1xEV-DV) will introduce
new radio techniques and an all-IP architecture for radio access
and CN. The completion of specifications was expected in 2003. It
promises data rates up to 3 Mbps.
SK Telecom and LG Telecom from Korea were the first operators to
launch CDMA2000 1x in October 2000. Since that time, only a few operators
have announced CDMA2000 1x service launches. Some operators
recently announced setting up CDMA2000 1xEV-DO trails [10].
The network architecture for a CDMA2000 network is shown in
Figure 2.3. The basic architecture is quite similar to the GSM/UMTS architecture.
The main differences are in the packet domain, where a packet data
switching node (PDSN) is used. It has a similar role to the serving GPRS support
node (SGSN) and gateway GPRS support node (GGSN) in UMTS.
Mobility management within 3GPP2, however, is based on mobile IP
(RFC2002) instead of GPRS mobility management in GSM/UMTS PS networks.
Furthermore, American National Standards Institute (ANSI)-41 MAP
signaling is used instead of GSM mobile application part (MAP) signaling.
Activities have started in 3GPP2 for evolution toward an all-IP network,
similar to the IMS activities in 3GPP.