3.2 Technology Capabilities
3.2.3. Third Generation Technology
worldwide and the business benefits of deploying an industry standard technology can be seen in nearly every aspect of a network deployment, from end-user devices, to applications to hardware (Siemens, 2002).
Operator driven studies have indicated that for a GSM operator to upgrade a GPRS capable network for EDGE working is approximately 7 - 15% of the total initial GSM investment.
For a GSM operator there will always be a basic requirement to enhance their network infrastructure to improve service over time. This may include the introduction of a packet layer via GPRS and other enhancements, which will make best use of their existing infrastructure and investment. It is also worth considering that if new base stations are installed they will be delivered EDGE ready, especially if they are from a mainstream manufacturer. This program of improvements will, by definition, move the operator towards a network infrastructure, which can then be upgraded to EDGE at very little incremental cost (Rysavy, 2002).
MTN's GSM network is 10 years old with numerous outdated radio base station equipment still being used. For MTN to upgrade its GPRS network to EDGE will require a huge capital outlay in order to upgrade the base station to the latest EDGE capable equipment. Extra transmission and software costs will also be incurred.
time connectivity. The 3G wireless technology will allow an individual to have immediate access to location-specific services which offer information on demand (Rysavy, 2002).
This mobile technology represents the convergence of various 2G wireless telecommunication systems into a single global system that includes both terrestrial and satellite components. One of the most important aspects of 3G wireless technology is its ability to unify existing cellular standards, such as Code Division Multiple Access (CDMA), GSM, and Time Division Multiple Access (TDMA), under one umbrella. To ensure a smooth transition towards 3G, the IMT-2000 was established by the International Telecommunication Union (ITU) to harmonise the different proposed 3G standards. To date, the ITU has decided on a single flexible standard with a choice of multiple access methods.
CDMA is perceived to be the predominant air interface since it can support a higher bandwidth (Ericsson, 2001).
Two 3G standards, wideband CDMA (WCDMA) and cdma2000 have emerged as the most prominent contenders. WCDMA is supported by current GSM-centric countries while cdma2000 is supported by current CDMA-centric countries. WCDMA is also commonly known as Universal Mobile Telecommunication System (UMTS). W-CDMA will require bandwidth of between 5 MHz and 10 MHz, making it a suitable platform for higher capacity applications. Subscribers are likely to access 3G wireless services initially via dual band terminal devices. UMTS has garnered the overwhelming majority of new 3G spectrum licences, with most operators worldwide planning on deploying UMTS networks. The primary benefits of UMTS include high spectral efficiency, high user densities and support for high bandwidth data applications (Siemens, 2002)
According to Ericsson (2001), WCDMA data channels can support up to 2 Mb/s of data throughput. However, exact throughput depends on what size channels the operator chooses to make available and the number of users active in the network. Thus, users can expect throughputs of up to 384 Kb/s, which will satisfy almost any communications-oriented application. Operators can use a common core network that supports multiple radio access networks, including GSM, GPRS, EDGE and WCDMA. This common core network uses the same network elements as GPRS. This is called the UMTS Multi-radio network and gives the
operators maximum flexibility in providing different services across their coverage areas. The network architecture for 3G is shown in Figure 3.4.
FIGURE 3.4; UMTS NETWORK ARCHITECTURE
Adapted From: Third Generation (3G) Wireless White Paper. [Online]. Available at http://www. trillium. com/pages/white papers (Last accessed: March 2004).
The 3G wireless networks consist of a Radio Access Network (RAN) and a core network.
The core network consists of a packet-switched domain, which includes the 3G Serving GPRS Support Nodes (SGSN) and Gateway GPRS Support Nodes (GGSN), which provide the same functionality as in the GPRS system. The GGSN provides the connection to external Packet Data Network (PDN), such as the Internet backbone or an X.25 network. Both the SGSN and GGSN interface with the Home Location Register (HLR) to retrieve the mobile user's profiles to facilitate call completion. The circuit-switched domain includes the 3G Mobile Switching Centre (MSC) for switching of voice calls. Charging for services and access is done through the Charging Gateway Function (CGF), which is also part of the core network. The RAN functionality is independent from the core network functionality (Trillium, 2000).
The main purpose of the RAN is to provide a connection between the handset and the core network and to isolate all the radio issues from the core network. The advantage is one core network supporting multiple access technologies. The RAN consists of two types of nodes, the Radio Base Station (Node B) and the Radio Network Controller (RNC). The Node B handles the radio transmission and reception to and from the handset over the radio interface (Uu). It is controlled from the RNC via the Iub interface. The RNC is the node that controls all UMTS Radio Access Network functions. It connects the UMTS Radio Access Network to the core network via the Iu interface. There are two distinct roles for the RNC, to serve and to control. It provides the radio resource management, handover control and support for the connections to circuit-switched and packet-switched domains (Trillium, 2000).
WCDMA is spectrally more efficient than GSM but it is the wideband nature that provides the greatest advantage. The ability to translate the available frequency spectrum into high data rates. This results in flexibility to manage multiple traffic types, including voice, narrowband data and wideband data. WCDMA is actually a combination of a code-division multiple access and time-division multiple access. Packet data users can share the same codes and/or time slots as other users or the network can assign users dedicated channels and time slots. One enhancement over GPRS is that the control channels that normally carry signaling data can also carry small amounts of packet data, which reduces setup time for data communications (Rysavy, 2002).
To further expand the number of applications that can operate effectively, UMTS employs a sophisticated Quality of Service architecture for data that provides for four fundamental traffic classes, including (Rysavy, 2002):
1. Conversational - real-time interactive data with controlled bandwidth and minimum delay such as voice-over-IP or video conferencing.
2. Streaming - continuous data with controlled bandwidth and some delay such as music or video.
3. Interactive - back-and-forth data without bandwidth control and some delay, such as Web browsing.
4. Background - lower priority data that is non-real-time such as batch transfers.
3.3 Technology Comparison