3G SYSTEMS
CHAPTER 1
Introduction to 3G
The telecommunications world is changing as the trends of media
convergence, industry consolidation, Internet and Internet Protocol (IP) technologies and mobile communications collide into one. Significant change will be bought about by this rapid evolution in technology, with Third Generation mobile Internet technology a radical departure from that came before in the first and even the second generations of mobile technology. Some of the changes include:
People will look at their mobile phone as much as they hold it to their ear. As such, 3G will be less safe than previous generations- because television and other multimedia services tend to attract attention to themselves- instead of hands-free kits, we will need eyes-free kits!
Data ("non-voice") uses of 3G will be as important as and very different from the traditional voice business Mobile communications will be similar in its capability to fixed communications, such that many people will only have a mobile phone.
The mobile phone will be used as an integral part of the majority of people's lives- it will not be an added accessory but a core part of how they conduct their daily lives. The mobile phone will become akin to a remote control or magic wand that lets people do what they want when they want.
Third Generation (3G) mobile devices and services will transform wireless communications into on-line, real-time connectivity. 3G wireless technology will allow
an individual to have immediate access to location-specific services that offer
information on demand. 3G can be thought of as 2.5G services such as GPRS plus entertainment (games, video, mobile multimedia) plus new terminals. It brings with it significantly more bandwidth. The first generation of mobile phones consisted of the
analog models that emerged in the early 1980s. The second generation of digital mobile phones appeared about ten years later along with the first digital mobile networks. During the second generation, the mobile telecommunications industry experienced exponential growth both in terms of subscribers as well as new types of value-added services. Mobile phones are rapidly becoming the preferred means of personal communication, creating the world's largest consumer electronics industry.
The rapid and efficient deployment of new wireless data and internet services has emerged as a critical priority for communications equipment manufacturers. Network components that enable wireless data services are fundamental to the next-generation network infrastructure. Wireless data services are expected to see the same explosive growth in demand that Internet services and wireless voice services have seen in recent years.
As with all new technology standards, there is uncertainty and the fear of displacement. Third Generation (3G) mobile is topical and contentious for several reasons:
Because the nature and form of mobile communications is so radically changed, many people do not understand how to make money in the nonvoice world, and do not understand their role in it 3G licenses have started being awarded around the world, necessitating that existing mobile communications companies in the 2G world think about and justify their continued existence 3G is based on a different technology platform- Code Division Multiple Access (CDMA)- that is unlike the Time Division Multiple Access (TDMA) technology that is widely used in the 2G world. GSM (Global System for Mobile Communications) was based on TDMA technology.
The US, Japanese and European mobile players all have different technology competences and are now unified in this single standard- the separate wireless evolution paths and European wireless leadership are thereby challenged Japanese network operators will be the first to implement 3G networks in the year 2001, and Japanese terminal manufacturers, who have not had much market share outside their home market, will be first with 3G terminals
Many industry analysts and other pundits have questioned the return on an investment in 3G technology- questioning whether network operators will be able to earn
an adequate return on the capital deployed in acquiring and rolling out a 3G network.
Many media and Internet companies have shown a strong interest in using 3G technology
as a new channel to distribute their content, opening the opportunity for new entrants and new partnerships and value chains.
This seminar report presents an overview of current technology trends

in the wireless technology market, a historical overview of the evolving wireless technologies and an examination of how the communications industry plans
to implement 3G wireless technology standards to address the growing demand for
wireless multimedia services.
CHAPTER 2
3G Wireless Market Drivers
Telecommunications service providers and network operators are
embracing the recently adopted global third generation (3G) wireless standards in order
to address emerging user demands and to provide new services. The concept of 3G
wireless technology represents a shift from voice-centric services to multimedia-oriented
(voice, data, video, fax) services. In addition, heavy demand for remote access to personalized data is fueling development of applications, such as the Wireless Application Protocol (WAP) and multimedia management, to complement the 3G protocols. Complementary standards, such as Bluetooth, will enable interoperability between a mobile terminal (phone, PDA etc.) and other electronic devices, such as a laptop/desktop and peripherals, providing added convenience to the consumer and allowing for the synchronization and uploading of information at all times.
According to Lehman Brothers, approximately 50 percent of current voice
services subscribers are expected to use wireless data services by 2007, instead of 25 percent as previously forecast1. Lehman Brothers further predicts that, within seven years, 18 percent of cellular revenues and 21 percent of PCS (personal communications services) revenue will come from wireless data services. Cellular subscriptions are forecast to exceed one billion by 20032, compared with the 306 million that was forecast
at the end of 1998, representing a compound annual growth of 29 percent. Demand for
voice services has traditionally been a market driver. However, today, demand for data services has emerged as an equally significant market driver. After many years of stasis, the telecommunications industry is undergoing revolutionary changes due to the impact
of increased demand for data services on wireline and wireless networks. Up until
recently, data traffic over mobile networks remained low at around 2% due to the bandwidth limitations of the present second-generation (2G) wireless networks. Today, new technologies are quickly emerging that will optimize the transport of data services
and offer higher bandwidth in a mobile environment. As a case in point, the increased use

of the Internet as an acceptable source for information distribution and retrieval, in conjunction with the increased demand for global mobility has created a need for 3G wireless communications protocols.
The third generation of mobile communications will greatly enhance the implementation of sophisticated wireless applications. Users will be able to utilize personal, location-based wireless information and interactive services. Also, many companies and corporations are restructuring their business processes to be able to fully exploit the opportunities provided by the emerging new wireless data services. Many advanced wireless services are already available today, and the introduction of 3G wireless technologies will add to their ubiquity.
CHAPTER 3
Existing Mobile Networks
3.1 First Generation Wireless Technology
The first generation of wireless mobile communications was based on Analog signaling. Analog systems, implemented in North America, were known as Analog Mobile Phone Systems (AMPS), while systems implemented in Europe and the rest of the world were typically identified as a variation of Total Access Communication Systems (TACS). Analog systems were primarily based on circuit- switched technology and designed for voice, not data.
3.2 Second Generation Wireless Technology
The second generation (2G) of the wireless mobile network was based on low-band digital data signaling. The most popular 2G wireless technology is known as Global Systems for Mobile Communications (GSM). GSM systems, first implemented in 1991, are now operating in about 140 countries and territories around the world. An estimated 248 million users now operate over GSM systems. GSM technology is a combination of Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA). The first GSM systems used a
25MHz frequency Spectrum in the 900MHz band. FDMA is used to divide the available 25MHz of bandwidth into 124 carrier frequencies of 200kHz each. Each frequency is then divided using a TDMA scheme into eight timeslots. The use of separate timeslots for transmission and reception simplifies the electronics in the mobile units. Today, GSM systems operate in the 900MHz and 1.8 GHz bands throughout the world with the exception of the Americas where they operate in the 1.9
GHz band.
In addition to GSM, a similar technology, called Personal Digital
Communications (PDC), using TDMA-based technology, emerged in Japan. Since then,
several other TDMA-based systems have been deployed worldwide and serve an estimated 89 million people worldwide. While GSM technology was developed in Europe, Code Division Multiple Access (CDMA) technology was developed in North America. CDMA uses spread spectrum technology to break up speech into small, digitized segments and encodes them to identify each call. CDMA systems have been implemented worldwide in about 30 countries and serve an estimated 44 million subscribers.
While GSM and other TDMA-based systems have become the dominant

2G wireless technologies, CDMA technology is recognized as providing clearer voice quality with less background noise, fewer dropped calls, enhanced security, greater reliability and greater network capacity. The Second Generation (2G) wireless networks mentioned above are also mostly based on circuit-switched technology. 2G wireless networks are digital and expand the range of applications to more advanced voice services, such as Called Line Identification. 2G wireless technology can handle some data capabilities such as fax and short message service at the data rate of up to 9.6 kbps, but it
is not suitable for web browsing and multimedia applications.
CHAPTER 4
Next Generation Mobile Networks
4.1 Second Generation (2G+) Wireless Networks
As stated in a previous section, the virtual explosion of Internet usage has had a tremendous impact on the demand for advanced wireless data communication services. However, the effective data rate of 2G circuit-switched wireless systems is relatively slow -- too slow for today's Internet. As a result, GSM, PDC and other TDMA- based mobile system providers and carriers have developed 2G+ technology that is packet-based and increases the data communication speeds to as high as 384kbps. These
2G+ systems are based on the following technologies: High Speed Circuit-Switched Data

(HSCSD), General Packet Radio Service (GPRS) and Enhanced Data Rates for Global
Evolution (EDGE) technologies.
HSCSD is one step towards 3G wideband mobile data networks. This circuit-switched technology improves the data rates up to 57.6kbps by introducing 14.4 kbps data coding and by aggregating 4 radio channels timeslots of 14.4 kbps.
GPRS is an intermediate step that is designed to allow the GSM world to
implement a full range of Internet services without waiting for the deployment of full- scale 3G wireless systems. GPRS technology is packet-based and designed to work in parallel with the 2G GSM, PDC and TDMA systems that are used for voice communications and for table look-up to obtain GPRS user profiles in the Location Register databases. GPRS uses a multiple of the 1 to 8 radio channel timeslots in the
200kHz-frequency band allocated for a carrier frequency to enable data speeds of up to
115kbps. The data is packetized and transported over Public Land Mobile Networks
(PLMN) using an IP backbone so that mobile users can access services on the Internet, such as SMTP/POP-based e-mail, ftp and HTTP-based Web services. For more information on GPRS, please see Trillium's General Packet Radio Service (GPRS) White Paper at http://trilliumwhats-new/wp_gprs.html
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EDGE technology is a standard that has been specified to enhance the throughput per timeslot for both HSCSD and GPRS. The enhancement of HSCSD is called ECSD, whereas the enhancement of GPRS is called EGPRS. In ECSD, the maximum data rate will not increase from 64 kbps due to the restrictions in the A interface, but the data rate per timeslot will triple. Similarly, in EGPRS, the data rate per timeslot will triple and the peak throughput, including all eight timeslots in the radio interface, will exceed 384 kbps.
GPRS networks consist of an IP-based Public Mobile Land Network

(PLMN), Base Station Services (BSS), Mobile handsets (MS), and Mobile Switching Centers (MSC) for circuit-switched network access and databases. The Serving GPRS Support Nodes (SGSN) and Gateway GPRS Support Nodes (GGSN) make up the PLMN. Roaming is accommodated through multiple PLMNs. SGSN and GGSN interface with the Home Location Register (HLR) to retrieve the mobile user's profiles to facilitate call completion. GGSN provides the connection to external Packet Data Network (PDN), e.g.
an Internet backbone or an X.25 network. The BSS consists of Base Transceiver Stations and Base Station Controllers. The Base Transceiver Station (BTS) receives and transmits over the air interfaces (CDMA, TDMA), providing wireless voice and data connectivity
to the mobile handsets. Base Station Controllers (BSC) route the data calls to the packet-

switched PLMN over a Frame Relay (FR) page link and the voice calls to the Mobile Switching Center (MSC). MSC switches the voice calls to circuit-switched PLMN network such as PSTN and ISDN. MSC accommodates the Visitor Location Register
(VLR) to store the roaming subscriber information. The reverse process happens at the

destination PLMN and the destination BSS. On the data side, the BSC routes the data calls to the SGSN, and then the data is switched to the external PDN through the GGSN
or to another mobile subscriber.
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The following is a brief description of each protocol layer in the GPRS network infrastructure:
§ Sub-Network Dependent Convergence Protocol (SNDCP): protocol that maps a network level protocol, such as IP or X.25, to the underlying logical page link control. SNDCP also provides other functions such as compression, segmentation and multiplexing of network-layer messages to a single virtual connection.
§ Logical Link Control (LLC): a data page link layer protocol for GPRS which functions similar to Link Access Protocol – D (LAPD). This layer assures the reliable transfer of user data across a wireless network.
§ Base Station System GPRS Protocol (BSSGP): processes routing and quality of service (QoS) information for the BSS. BSSGP uses the Frame Relay Q.922 core protocol as its transport mechanism.
§ GPRS Tunnel Protocol (GTP): protocol that tunnels the protocol data units through the IP backbone by adding routing information. GTP operates on top of TCP/UDP over
IP.
§ GPRS Mobility Management (GMM/SM): protocol that operates in the signaling plane of GPRS, handles mobility issues such as roaming, authentication, selection of encryption algorithms and maintains PDP context.
§ Network Service: protocol that manages the convergence sub-layer that operates between BSSGP and the Frame Relay Q.922 Core by mapping BSSGP's service requests
to the appropriate Frame Relay services.
§ BSSAP+: protocol that enables paging for voice connections from MSC via SGSN, thus optimizing paging for mobile subscribers. BSSAP+ is also responsible for location and routing updates as well as mobile station alerting.
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§ SCCP, MTP3, MTP2 are protocols used to support Mobile Application Part (MAP)
and BSSAP+ in circuit switched PLMNs.
§ Mobile Application Part (MAP): supports signaling between SGSN/GGSN and
HLR/AuC/EIR.
4.2 Third Generation (3G) Wireless Networks
It represents the convergence of various 2G wireless telecommunications 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 CDMA, GSM, and TDMA, under one umbrella. The following three air interface modes accomplish this result: wideband CDMA, CDMA2000 and the Universal Wireless Communication (UWC-136) interfaces.
Wideband CDMA (W-CDMA) is compatible with the current 2G GSM networks prevalent in Europe and parts of Asia. W-CDMA will require bandwidth of between 5Mhz and 10 MHz, making it a suitable platform for higher capacity applications. It can be overlaid onto existing GSM, TDMA (IS-36) and IS95 networks. Subscribers are likely to access 3G wireless services initially via dual band terminal devices. W-CDMA networks will be used for high-capacity applications and 2G digital wireless systems will be used for voice calls.
The second radio interface is CDMA 2000 which is backward compatible

with the second generation CDMA IS-95 standard predominantly used in US. The third radio interface, Universal Wireless Communications – UWC-136, also called IS-136HS, was proposed by the TIA and designed to comply with ANSI-136, the North American TDMA standard.
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 3G SGSNs and GGSNs, which provide the same functionality that they provide in a GPRS system, and a circuit-switched domain, which includes 3G MSC for switching of voice calls. Charging for services and access is done through the Charging Gateway Function





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(CGF), which is also part of the core network. RAN functionality is independent from the core network functionality. The access network provides a core network technology independent access for mobile terminals to different types of core networks and network services. Either core network domain can access any appropriate RAN service; e.g. it should be possible to access a “speech” radio access bearer from the packet switched domain.
The Radio Access Network consists of new network elements, known as Node B and Radio Network Controllers (RNCs). Node B is comparable to the Base Transceiver Station in 2G wireless networks. RNC replaces the Base Station Controller.
It provides the radio resource management, handover control and support for the

connections to circuit-switched and packet-switched domains. The interconnection of the network elements in RAN and between RAN and core network is over Iub, Iur and Iu interfaces based on ATM as a layer 2 switching technology. Data services run from the terminal device over IP, which in turn uses ATM as a reliable transport with QoS. Voice
is embedded into ATM from the edge of the network (Node B) and is transported over ATM out of the RNC. The Iu interface is split into 2 parts: circuit switched and packet- switched. The Iu interface is based on ATM with voice traffic embedded on virtual circuits using AAL2 technology and IP-over-ATM for data traffic using AAL5 technology. These traffic types are switched independently to either 3G SGSN for data or
3G MSC for voice.
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The following is a brief description of each protocol layer in a 3G wireless network infrastructure:
§ Global Mobility Management (GMM): protocol that includes attach, detach, security, and routing area update functionality.
§ Node B Application Part (NBAP): provides procedures for paging distribution, broadcast system information and management of dedicated and logical resources.
§ Packet Data Convergence Protocol (PDCP): maps higher level characteristics onto the characteristics of the underlying radio-interface protocols. PDCP also provides protocol transparency for higher layer protocols.
§ Radio Link Control (RLC): provides a logical page link control over the radio interface.
§ Medium Access Control (MAC): controls the access signaling (request and grant)
procedures for the radio channel.
§ Radio resource Control (RRC): manages the allocation and maintenance of radio communication paths.
§ Radio Access Network Application Protocol (RANAP): encapsulates higher layer signaling. Manages the signaling and GTP connections between RNC and 3G-SGSN, and signaling and circuit-switched connections between RNC and 3G MSC.
§ Radio Network Service Application Part (RNSAP): provides the communication between RNCs.
§ GPRS Tunnel Protocol (GTP): protocol that tunnels the protocol data units through the IP backbone by adding routing information. GTP operates on top of TCP/UDP over
IP.
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§ Mobile Application Part (MAP): supports signaling between SGSN/GGSN and
HLR/AuC/EIR.
§ AAL2 Signaling (Q.2630.1, Q.2150.1, Q.2150.2, AAL2 SSSAR, and AAL2 CPS):
protocols suite used to transfer voice over ATM backbone using ATM adaptation layer 2.
§ Sigtran (SCTP, M3UA): protocols suite used to transfer SCN signaling protocols over
IP network.