Universal Mobile = Telecommunications=20 System
![=](3D"http://en.wikipedia.org/wiki/File:UMTS_Network_Architecture.svg"){kind=link}
Universal Mobile Telecommunications System (UMTS) is one of =
the
Unlike EDGE (IMT Single-Carrier, = based on=20 GSM) and CDMA2000 (IMT=20 Multi-Carrier), UMTS requires new base stations and new frequency = allocations.=20 However, it is closely related to GSM/EDGE as it borrows and builds upon = concepts from GSM. Further, most UMTS handsets also support GSM, = allowing=20 seamless dual-mode operation. Therefore, UMTS is sometimes marketed as=20 3GSM, emphasizing the close relationship with GSM and = differentiating it=20 from competing technologies.
The name UMTS, introduced by ETSI, is usually used in =
Europe.=20
Outside of Europe, the system is also known by other names such as FOMA
Contents |
[edit]= =20 Features
UMTS, using 3GPP,=20
supports maximum theoretical data transfer =
rates of 42=20
Mbit/s (with
Precursors to 3G are 2G mobile telephony =
systems, such as=20
GSM,=20
IS-95, =
Since 2006, UMTS networks in many countries have been or are in the =
process=20
of being upgraded with H=
igh Speed=20
Downlink Packet Access (HSDPA), sometimes known as 3.5G. =
Currently, HSDPA=20
enables downlink transfer =
speeds of up=20
to 21 Mbit/s. Work is also progressing on improving the uplink transfer =
speed=20
with the Hig=
h-Speed=20
Uplink Packet Access (HSUPA). Longer term, the
The first national consumer UMTS networks launched in 2002 with a =
heavy=20
emphasis on telco-provided mobile applications such as mobile TV and
[edit]= =20 Technology
UMTS combines three different air interfaces, GSM's=20 Mobile = Application=20 Part (MAP) core, and the GSM family of speech codecs.
[edit]= =20 Air interfaces
UMTS provides several different terrestrial air interfaces, =
called=20
UMTS Terrestrial Radio Access (UTRA).
Please note that the terms W-CDMA, TD-CDMA and TD-SCDMA are =
misleading. While=20
they suggest covering just a channel =
access=20
method (namely a variant of CDMA), they are actually =
the common=20
names for the whole air interface standards.
Non-terrestrial radio access networks are currently under = research.
[edit]= =20 W-CDMA = (UTRA-FDD)
![3D""=20](3D"http://en.wikipedia.org/wiki/File:UMTS-fridge.jpg")
=20
W-CDMA uses the DS-CDMA channel access = method=20 with a pair of 5 MHz channels. In contrast, the competing CDMA2000 system uses = one or=20 more arbitrary 1.25 MHz channels for each direction of = communication.=20 W-CDMA systems are widely criticized for their large spectrum usage, = which has=20 delayed deployment in countries that acted relatively slowly in = allocating new=20 frequencies specifically for 3G services (such as the United = States).
The specific frequency bands =
originally=20
defined by the UMTS standard are 1885=E2=80=932025 MHz for the =
mobile-to-base=20
(uplink) and 2110=E2=80=932200 MHz for the base-to-mobile =
(downlink). In the US,=20
1710=E2=80=931755 MHz and 2110=E2=80=932155 MHz will be used =
instead, as the=20
1900 MHz band was already used.
W-CDMA is a part of IMT-2000 as IMT Direct Spread.
[edit]= =20 UTRA-TDD HCR
UMTS-TDD's=20
air interfaces that use the TD-CDMA channel access =
technique=20
are standardized as UTRA-TDD HCR, which uses increments of =
5 MHz of=20
spectrum, each slice divided into 10ms frames containing fifteen time =
slots=20
(1500 per second)
TD-CDMA is a part of IMT-2000 as IMT CDMA TDD.
[edit] =
=20
TD-SCDMA (UTRA-TDD 1.28 Mcps Low Chip =
Rate)
TD-SCDMA uses the TDMA<=
/A>=20
channel access method combined with an adaptive synchronous=20
CDMA component
Like TD-CDMA, it is known as IMT CDMA TDD within IMT-2000.
[edit]= =20 Radio access = network
UMTS also specifies the UMTS Terrestrial Radio Access Network=20 (UTRAN), which is composed of multiple base stations, possibly = using=20 different terrestrial air interface standards and frequency bands.
UMTS and GSM/EDGE can share a Core Network (CN), making UTRAN an = alternative=20 radio access network to GERAN (GSM/EDGE RAN), = and allowing=20 (mostly) transparent switching between the RANs according to available = coverage=20 and service needs. Because of that, UMTS' and GSM/EDGE's radio access = networks=20 are sometimes collectively referred to as UTRAN/GERAN.
UMTS networks are often combined with GSM/EDGE, the later of which is = also a=20 part of IMT-2000.
The UE (User Equipment) interface of the RAN (Radio Access Network) = primarily=20 consists of RRC (Radio Resource Control), RLC (Radio Link Control) and = MAC=20 (Media Access Control) protocols. RRC protocol handles connection = establishment,=20 measurements, radio bearer services, security and handover decisions. = RLC=20 protocol primarily divides into three Modes - Transparent Mode (TM),=20 Unacknowledge Mode (UM), Acknowledge Mode (AM). The functionality of AM = entity=20 resembles TCP operation where as UM operation resembles UDP operation. = In TM=20 mode, data will be sent to lower layers without adding any header to SDU = of=20 higher layers. MAC handles the scheduling of data on air interface = depending on=20 higher layer (RRC) configured parameters.
Set of properties related to data transmission is called Radio Bearer = (RB).=20 This set of properties will decide the maximum allowed data in a TTI=20 (Transmission Time Interval). RB includes RLC information and RB = mapping. RB=20 mapping decides the mapping between RB<->logical = channel<->transport=20 channel. Signaling message will be send on Signaling Radio Bearers = (SRBs) and=20 data packets (either CS or PS) will be sent on data RBs. RRC and NAS = messages=20 will go on SRBs.
Security includes two procedures: integrity and ciphering. Integrity=20 validates the resource of message and also make sure that no one = (third/unknown=20 party) on radio interface has not modified message. Ciphering make sure = that no=20 one listens your data on air interface. Both integrity and ciphering = will be=20 applied for SRBs where as only ciphering will be applied for data = RBs.
[edit]= =20 Core network
With Mobile Application Part, UMTS uses the same core network = standard=20 as GSM/EDGE. This allows a simple migration for existing GSM operators. = However,=20 the migration path to UMTS is still costly: while much of the core=20 infrastructure is shared with GSM, the cost of obtaining new spectrum = licenses=20 and overlaying UMTS at existing towers is high.
The CN can be connected to various backbone networks =
like the
[edit]= =20 Spectrum = allocation
Over 130 licenses have already been awarded to operators worldwide = (as of=20 December 2004), specifying W-CDMA radio access = technology=20 that builds on GSM.=20 In Europe, the license process occurred at the tail end of the = technology=20 bubble, and the auction mechanisms for allocation set up in some = countries=20 resulted in some extremely high prices being paid for the original = 2100 MHz=20 licenses, notably in the UK and Germany. In Germany, bidders paid = a total=20 =E2=82=AC50.8 billion for six licenses, two of which were subsequently = abandoned and=20 written off by their purchasers (Mobilcom=20 and the Sonera/Telefonica=20 consortium). It has been suggested that these huge license fees have the = character of a very large tax paid on future income expected many years = down the=20 road. In any event, the high prices paid put some European telecom = operators=20 close to bankruptcy (most notably KPN). Over the last few = years some=20 operators have written off some or all of the license costs. More = recently, a=20 carrier in Finland has begun using 900 MHz UMTS in a shared = arrangement=20 with its surrounding 2G GSM base stations, a trend that is expected to = expand=20 over Europe in the next 1=E2=80=933 years.
The 2100 MHz UMTS spectrum allocated in Europe is already used =
in North=20
America. The 1900 MHz range is used for 2G (
AT&T Wireless launched UMTS services in the United States by the = end of=20 2004 strictly using the existing 1900 MHz spectrum allocated for 2G = PCS=20 services. Cingular acquired AT&T Wireless in 2004 and has since then = launched UMTS in select US cities. Cingular renamed itself AT&T and is rolling = out some=20 cities with a UMTS network at 850 MHz to enhance its existing UMTS = network=20 at 1900 MHz and now offers subscribers a number of UMTS 850/1900=20 phones.
T-Mobile's=20 rollout of UMTS in the US will focus on the 2100/1700 MHz = bands.
In Canada, UMTS coverage is being provided on the 850 MHz and=20
1900 MHz band on the Rogers, Bell, and Telus networks. Recently, =
new=20
providers Wind Mobile and Mobilicity,=20
have begun operations in the 2100/1700 MHz bands and Quebecor and
In 2008, Australian telco Telstra replaced its =
existing=20
CDMA network with a national 3G network, branded as NextG, =
operating in=20
the 850 MHz band. Telstra currently provides UMTS service on this =
network,=20
and also on the 2100 MHz UMTS network, through a co-ownership of =
the owning=20
and administrating company 3GIS. This company is also co-owned by
In India BSNL has started its 3G = services=20 since October 2009 beginning with the larger cities and then expanding = over to=20 smaller cities. The 850 MHz and 900 MHz bands provide greater = coverage=20 compared to equivalent 1700/1900/2100 MHz networks, and are best = suited to=20 regional areas where greater distances separate subscriber and base = station.
Carriers in South America are now also rolling out 850 MHz = networks.
[edit]=20
Interoperability=20
and global roaming
UMTS phones (and data cards) are highly portable=E2=80=94they have = been designed to=20 roam easily onto other UMTS networks (if the providers have roaming = agreements=20 in place). In addition, almost all UMTS phones are UMTS/GSM dual-mode = devices,=20 so if a UMTS phone travels outside of UMTS coverage during a call the = call may=20 be transparently handed off to available GSM coverage. Roaming charges = are=20 usually significantly higher than regular usage charges.
Most UMTS licensees consider ubiquitous, transparent global roaming an important = issue. To=20 enable a high degree of interoperability, UMTS phones usually support = several=20 different frequencies in addition to their GSM fallback. Different = countries=20 support different UMTS = frequency=20 bands =E2=80=93 Europe initially used 2100 MHz while the most = carriers in the=20 USA use 850Mhz and 1900Mhz. T-mobile has launched a network in the US = operating=20 at 1700 MHz (uplink) /2100 MHz (downlink), and these bands are = also=20 being adopted elsewhere in the Americas. A UMTS phone and network must = support a=20 common frequency to work together. Because of the frequencies used, = early models=20 of UMTS phones designated for the United States will likely not be = operable=20 elsewhere and vice versa. There are now 11 different frequency = combinations used=20 around the world=E2=80=94including frequencies formerly used solely for = 2G services.
UMTS phones can use a Universal=20
Subscriber Identity Module, USIM (based on GSM's
Japan was the first country to adopt 3G technologies, and since they =
had not=20
used GSM previously they had no need to build GSM compatibility into =
their=20
handsets and their 3G handsets were smaller than those available =
elsewhere. In=20
2002, NTT=20
DoCoMo's FOMA=20
3G network was the first commercial UMTS network=E2=80=94using a =
pre-release=20
specification
[edit]=20 Handsets and = modems
![=](3D"http://en.wikipedia.org/wiki/File:Option_GT_3G%2B_UMTS_card.jpg"){kind=link}
![3D""=20](3D"http://en.wikipedia.org/wiki/File:Nokia6650_unlocked.jpg")
All of the major 2G phone manufacturers (that are still in business) = are now=20 manufacturers of 3G phones. The early 3G handsets and modems were = specific to=20 the frequencies required in their country, which meant they could only = roam to=20 other countries on the same 3G frequency (though they can fall back to = the older=20 GSM standard). Canada and USA have a common share of frequencies, as do = most=20 European countries. The article UMTS = frequency=20 bands is an overview of UMTS network frequencies around the = world.
Using a cellular =
router, PCMCIA=20
or USB card, customers are able to access 3G broadband services, =
regardless of=20
their choice of computer (such as a tablet PC or a
There are almost no 3G phones or modems available supporting all 3G=20 frequencies (UMTS850/900/1700/1900/2100 MHz). However, many phones = are=20 offering more than one band which still enables extensive roaming. For = example,=20 a tri-band chipset operating on 850/1900/2100 MHz, such as that = found in=20 Apple's iPhone,=20 allows usage in the majority of countries where UMTS-FDD is = deployed.
[edit]=20 Other competing = standards
The main competitor to UMTS is CDMA2000 (IMT-MC), =
which is=20
developed by the 3GPP2. Unlike UMTS, =
CDMA2000 is an=20
evolutionary upgrade to an existing 2G standard, cdmaOne, and is=20
able to operate within the same frequency allocations. This and =
CDMA2000's=20
narrower bandwidth requirements make it easier to deploy in existing =
spectra. In=20
some, but not all, cases, existing GSM operators only have enough =
spectrum to=20
implement either UMTS or GSM, not both. For example, in the US
Another competitor to UMTS is EDGE (IMT-SC), which is = an=20 evolutionary upgrade to the 2G GSM system, leveraging existing GSM = spectrums. It=20 is also much easier, quicker, and considerably cheaper for wireless = carriers to=20 "bolt-on" EDGE functionality by upgrading their existing GSM = transmission=20 hardware to support EDGE than having to install almost all brand-new = equipment=20 to deliver UMTS. However, being developed by 3GPP just as UMTS, EDGE = is not a=20 true competitor. Instead, it is used as a temporary solution preceding = UMTS=20 roll-out or as a complement for rural areas. This is facilitated by the = fact=20 that GSM/EDGE and UMTS specification are jointly developed and rely on = the same=20 core=20 network, allowing dual-mode operation including vertical=20 handovers.
China's TD-SCDMA standard is = often seen=20 as a competitor, too. TD-SCDMA has been added to UMTS' Release 4 as = UTRA-TDD=20 1.28 Mcps Low Chip Rate (UTRA-TDD LCR). Unlike TD-CDMA (UTRA-TDD 3.84 = Mcps High=20 Chip Rate, UTRA-TDD HCR) which complements W-CDMA (UTRA-FDD), it = is suitable=20 for both micro and macro cells. However, the lack of vendors' support is = preventing it from being a real competitor.
While DECT is technically = capable of=20 competing with UMTS and other cellular networks in densely-populated, = urban=20 areas, it has only been deployed for domestic cordless phones and = private=20 in-house networks.
All of these competitors have been accepted by ITU as part of the
On the Internet access side, competing systems include WiMAX and Flash-OFDM.
[edit]=20
Migrating =
from GPRS to=20
UMTS
From GPRS network, the following network elements can be reused:
- Home = Location=20 Register (HLR)
- Visitor Location Register (VLR)
- Equipment Identity Register (EIR)
- Mobile = Switching=20 Center (MSC) (vendor dependent)
- Authenticatio= n=20 Center (AUC)
- Serving GPRS Support Node (SGSN) (vendor = dependent)
- Gateway GPRS Support Node (GGSN)
From Global Service for Mobile (GSM) communication radio network, the = following elements cannot be reused
- Base station controller (BSC)
- Base transceiver station (BTS)
They can remain in the network and be used in dual network operation = where 2G=20 and 3G networks co-exist while network migration and new 3G terminals = become=20 available for use in the network.
The UMTS network introduces new network elements that function as = specified=20 by 3GPP:
- Node B=20 (base transceiver station)
- Radio = Network=20 Controller (RNC)
- Media Gateway (MGW)
The functionality of MSC and SGSN changes when going to UMTS. In a = GSM system=20 the MSC handles all the circuit switched operations like connecting A- = and=20 B-subscriber through the network. SGSN handles all the packet switched=20 operations and transfers all the data in the network. In UMTS the Media = gateway=20 (MGW) take care of all data transfer in both circuit and packet switched = networks. MSC and SGSN control MGW operations. The nodes are renamed to=20 MSC-server and GSN-server.
[edit]=20 Problems and = issues
Some countries, including the United States and Japan, have allocated = spectrum differently from the ITU=20 recommendations, so that the standard bands most commonly used for UMTS=20 (UMTS-2100) have not been available. In those countries, alternative = bands are=20 used, preventing the interoperability of existing UMTS-2100 equipment, = and=20 requiring the design and manufacture of different equipment for the use = in these=20 markets. As is the case with GSM900 today, standard UMTS 2100 MHz = equipment=20 will not work in those markets. However, it appears as though UMTS is = not=20 suffering as much from handset band compatibility issues as GSM did, as = many=20 UMTS handsets are multi-band in both UMTS and GSM modes. Quad-band GSM = (850,=20 900, 1800, and 1900 MHz bands) and tri-band UMTS (850, 1900, and=20 2100 MHz bands) handsets are becoming more commonplace.
The early days of UMTS saw rollout=20 hitches in many countries. Overweight handsets with poor battery = life were=20 first to arrive on a market highly sensitive to weight and form factor. = The=20 Motorola A830, a debut handset on Hutchison's 3 network, weighed more = than 200=20 grams and even featured a detachable camera to reduce handset weight. = Another=20 significant issue involved call reliability, related to problems with = handover=20 from UMTS to GSM. Customers found their connections being dropped as = handovers=20 were possible only in one direction (UMTS =E2=86=92 GSM), with the = handset only changing=20 back to UMTS after hanging up. In most networks around the world this is = no=20 longer an issue.
Compared to GSM, UMTS networks initially required a higher base =
station=20
density. For fully-fledged UMTS incorporating video on =
demand=20
features, one base station =
needed to be=20
set up every 1=E2=80=931.5 km =
(0.62=E2=80=930.93
Even with current technologies and low-band UMTS, telephony and data =
over=20
UMTS is still more power intensive than on comparable GSM networks.
[edit]=20 Releases
The evolution of UMTS progresses according to planned releases. Each = release=20 is designed to introduce new features and improve upon existing = ones.
[edit]=20 Release '99
- Bearer services
- 64 kbit/s circuit switch
- 384 kbit/s packet switched
- Location services
- Call services: compatible with Global=20 System for Mobile Communications (GSM), based on Universal=20 Subscriber Identity Module (USIM)
[edit]=20 Release 4
- Edge radio
- Multimedia messaging
- MExE (Mobile Execution Environment)
- Improved location services
- IP Multimedia Services (IMS)
[edit]=20 Release 5
- IP = Multimedia=20 Subsystem (IMS)
- IPv6, IP=20 transport in UTRAN
- Improvements in GERAN, MExE, etc
- HSDPA
[edit]=20 Release 6
[edit]=20 Release 7
- Enhanced L2
- 64 QAM , MIMO
- VoIP over HSPA
- CPC - continuous packet connectivity
- FRLC - Flexible RLC
[edit]=20 Release 8
- DC-HSPA
- HSUPA 16QAM
[edit]=20 See also
- List= of=20 Deployed UMTS networks
- 3G
- 3GPP: the body=20 that manages the UMTS standard.
- 3GPP = Long Term=20 Evolution, the 3GPP project to evolve = UMTS=20 towards 4G=20 capabilities.
- GAN/UMA:= A=20 standard for running GSM and UMTS over wireless LANs.
- =
Opportunity=20
Driven Multiple Access, ODMA: a UMTS TDD mode communications =
- HSDPA, HSUPA: = updates to=20 the W-CDMA air interface.
- PDCP
- Subscrib= er=20 Identity Module
- UMTS-TDD: a variant = of UMTS=20 largely used to provide wireless Internet service.
- UMTS = frequency=20 bands
- W-CDMA: the primary = air=20 interface standard used by UMTS.
- W-CDMA = 2100
Other, non-UMTS, 3G=20 and 4G = standards:
- CDMA2000: evolved =
from the
- FOMA
- TD-SCDMA
- WiMAX: a=20 newly emerging wide area wireless technology.
UMTS is an evolution of the GSM mobile phone standard.
Other useful information
- Mobile = modem
- Spectral=20 efficiency comparison table
- Code = Division Multiple Access (CDMA)
- Common = pilot=20 channel or CPICH, a simple synchronisation channel in WCDMA.
- Multiple-input=20 multiple-output (MIMO) is the major issue of multiple = antenna=20 research.
- Wi-Fi: a=20 local area wireless technology that is complementary to UMTS.
- List = of device=20 bandwidths
- O= perations=20 and Maintenance Centre
- Radio = Network=20 Controller
- UMTS = security
[edit]=20 Literature
- Martin Sauter: Communication Systems for the Mobile Information = Society, John Wiley, September 2006, ISBN= =20 0-470-02676-6
- Ahonen and Barrett (editors), Services for UMTS (Wiley, = 2002) first=20 book on the services for 3G, I= SBN=20 978-0-471-48550-6
- Holma and Toskala (editors), WCDMA for UMTS, (Wiley, 2000) = first=20 book dedicated to 3G technology, I= SBN=20 978-0-471-72051-5
- Kreher and Ruedebusch, UMTS Signaling: UMTS Interfaces, =
Protocols,=20
Message Flows and Procedures Analyzed and Explained (Wiley 2007), =
- Laiho, Wacker and Novosad, Radio Network Planning and = Optimization for=20 UMTS (Wiley, 2002) first book on radio network planning for 3G, I= SBN=20 978-0-470-01575-9
[edit]=20 Notes
[edit]=20 References
- ^
[edit]=20 External links
![3D""=20](3D"http://upload.wikimedia.org/wikipedia/commons/thumb/4/4a/Commons-l=)
- 3GPP Specifications Numbering Schemes
- Vocabulary for 3GPP Specifications, up to Release = 8
- UMTS FAQ on UMTS World
- Worldwide W-CDMA frequency allocations on UMTS = World
- UMTS=20 TDD Alliance The Global UMTS TDD Alliance
- 3GSM World Congress
- UMTS=20 Provider Chart
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