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3G and Beyond
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Integration of voice and data traffic
Multimedia applications require both voice and
data.
The main feature of 3G cell phone systems is to
handle both voice and data so users can accessthe Internet and e-mail, listen to music, watch
movies, use navigation, etc.
Data oriented systems, e.g., 802.11 need to
handle voice, too, due to the use of Voice over
IP.
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Drawbacks of voice oriented systems
unused capacity
In TDMA/FDMA, a number of channels areassigned to a cell. When the number ofactive users falls below the available
number of channels, some portion of theavailable capacity is not used.
Speech appears in spurts, and two partiesdont speak simultaneously. A typical two-way conversation only use 40% of theconnection time.
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Drawbacks of data networks
Quality of Service is not guaranteed. Data
are transmitted in packets. There can be
delays and interruptions, which are not
tolerated in voice transmission
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Evolution of cellular systems (2G)
2G:
GSM: European TDMA
D-AMPS (Digital-Advanced Mobile Phone
System): IS-54 and IS-136 which are TDMAstandards used in the US and have been
replaced by GSM or TDMA2000.
IS-95: IS-95/cdmaOne, CDMA in the US
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Evolution of cellular systems (2.5G)
2.5G
GPRS (General Packet Radio Service)
To transmit and receive TCP/IP based data to and
from GPRS mobile devices
HSCSD: High-speed circuit-switched data,
which is a part of EDGE and UMTS
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Evolution of cellular systems (2.75G)
CDMA2000, 3G standard in the US
EDGE (Enhanced Data for Global Evolution) is a
method to increase the data rates by introducing
a new modulation technique and channelcoding, and thus an add-on to GPRS. EDGE
can transmit three times as many bits as GPRS
during the same period of time.
It uses phase modulation. With 8 phase shift,
three consecutive bits are mapped onto one
symbol. Thus the data rate increases 3 times.
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Comparison: GPRS and EDGE
GPRS EDGE
Symbol rate 270 ksym/s 270 ksym/s
Modulation bit rate 270 kb/s 810 kb/s
data rate/time slot 20 kb/s 59,2 kb/s
data rate/8 time slots 160 kb/s 473,6 kb/s
8
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Evolution of cellular systems (3G)
W-CDMA, European 3G
1xEV-DO (1xEvolution-Data
Optimized)/IS-856, developed by
Qualcomm in 1999 to meet IMT-2000
requirements. US 3G provided by Sprint
and Verizon. Download speed 2.5-3 Mbps.
TD-SCDMA (Time Division-Synchronous
CDMA), Chinese 3G
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Evolution of TDMA
TDMA
GSM
IS-54IS-136
GPRS
(General PacketRadio Service)
EDGE(Enhanced Data
rates for GSMEvolution)
WCDMA
UMTS(Universal MobileTelecom System)
2.5G 2.5G 3G2G
2G
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GPRS (General Packet Radio Service)
Based on GSM
GPRS does not require permanently
allocated physical channels (frequencies
and time slots).
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GPRS (contd.)
Phase 2+ (2.5G)
It provides an "always on", high-speed connection (up to171 kbps in theory, typical 56 kbps) to packet datanetworks, which is suited to the "bursty" traffic on the
Internet and World Wide Web, either directly or viaoperators' portals.
With GPRS, the core network is enhanced to embracethe packet switched domain, adding new IP-connectednetwork elements. Crucially, this extension lays the
foundations of a common core network for 2G and 3G.
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EDGE (Enhanced Data rates for GSM Evolution)
EDGE further enhances GSM/GPRS radio interface byadopting new modulation technology to achieve higherdata rates (180 kbps) using existing GSM radiospectrum.
EDGE is the other pre-3G radio access technologydirectly evolved from GSM. It includes advanced Qualityof Service mechanisms,
Limited data rates compared with WCDMA/TD-SCDMA.Used to provide 3G services in existing 2G spectrumresources.
WCDMA and TD-SCDMA will not necessarily replaceGPRS or EDGE, but will in reality co-exist with them, andcan share one common core network.
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UMTS
UMTS introduces WCDMA for paired bands(5MHz each), as well as TD-SCDMA and TD-CDMA for unpaired bands.
to support High Speed Downlink and Uplink
Packet Access (HSDPA, sometimes called3.5G), enabling transmission at speeds of up to14.2 Mbit/s.
IP Multimedia Subsystem (IMS). It enables real-
time, person-to-person services, such as voiceor video telephony, to be provided by means ofpacket switched technology in common withnon-real-time information and data services.
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UMTS (contd.)
The ability to work with other networks
such as Digital Video Broadcasting (DVB)
and Digital Audio Broadcasting (DAB)
To take advantage of the content offerings
that can be delivered efficiently to phones.
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3GPP (Third Generation Partnership Project)
Established in December 1998
Represents 437 operators and vendorsworldwide. It brings together a number oftelecommunications standards bodies, currently
ARIB and TTC (Japan), CCSA (China), ETSI(Europe), T1 (USA) and TTA (Korea).
to produce globally applicable TechnicalSpecifications and Technical Reports based on
GSM, FDD and TDD. Include GPRS and EDGE.
Standardize WCDMA and CDMA/TD
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GAN/UMA (Generic Access
Network/Unlicensed Mobile Access)
Allowing seamless roaming and handover
between Wi-Fi network and cellular networks
Advantages:
Cheap way to expand coverageRelieves congestion on the cellular spectrum by using
relatively low cost Internet
Particularly good for operators that also offer Internet
services. Can promote both cellular and Internetservices
Improve receiving condition at homes
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The future
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CDMA-2000 family
EV-DV (Evolution-Data and Voice) EV-DVstandard was less attractive to operators,and has not been implemented.
EV-DO (Evolution-Data Optimized) It isstandardized by 3rd GenerationPartnership Project 2 (3GPP2) as part ofthe CDMA2000 family of standards. Dataspeed can reach 2.4 Mbit/s with Rev. 0and up to 3.1 Mbit/s with Rev. A.