Transcript Document

3G and Beyond
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 access
the 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 are
assigned to a cell. When the number of
active users falls below the available
number of channels, some portion of the
available capacity is not used.
Speech appears in spurts, and two parties
don’t speak simultaneously. A typical twoway conversation only use 40% of the
connection 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 TDMA
standards used in the US and have been
replaced by GSM or TDMA2000.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 channel
coding, 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
Symbol rate
Modulation bit rate
data rate/time slot
data rate/8 time slots
EDGE
270 ksym/s 270 ksym/s
270 kb/s 810 kb/s
20 kb/s
59,2 kb/s
160 kb/s
473,6 kb/s
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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
GSM
TDMA
2G
GPRS
EDGE
WCDMA
UMTS
(General Packet
Radio Service)
(Enhanced Data
rates for GSM
Evolution)
(Universal Mobile
Telecom System)
2.5G
2.5G
3G
IS-54
IS-136
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 to
171 kbps in theory, typical 56 kbps) to packet data
networks, which is suited to the "bursty" traffic on the
Internet and World Wide Web, either directly or via
operators' portals.
 With GPRS, the core network is enhanced to embrace
the packet switched domain, adding new IP-connected
network 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 by
adopting new modulation technology to achieve higher
data rates (180 kbps) using existing GSM radio
spectrum.
 EDGE is the other pre-3G radio access technology
directly evolved from GSM. It includes advanced Quality
of Service mechanisms,
 Limited data rates compared with WCDMA/TD-SCDMA.
Used to provide 3G services in existing 2G spectrum
resources.
 WCDMA and TD-SCDMA will not necessarily replace
GPRS or EDGE, but will in reality co-exist with them, and
can share one common core network.
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UMTS
 UMTS introduces WCDMA for paired bands
(5MHz each), as well as TD-SCDMA and TDCDMA for unpaired bands.
 to support High Speed Downlink and Uplink
Packet Access (HSDPA, sometimes called
3.5G), enabling transmission at speeds of up to
14.2 Mbit/s.
 IP Multimedia Subsystem (IMS). It enables realtime, person-to-person services, such as voice
or video telephony, to be provided by means of
packet switched technology in common with
non-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 vendors
worldwide. It brings together a number of
telecommunications standards bodies, currently
ARIB and TTC (Japan), CCSA (China), ETSI
(Europe), T1 (USA) and TTA (Korea).
 to produce globally applicable Technical
Specifications 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 coverage
Relieves 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 Internet
services
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-DV
standard was less attractive to operators,
and has not been implemented.
EV-DO (Evolution-Data Optimized) It is
standardized by 3rd Generation
Partnership Project 2 (3GPP2) as part of
the CDMA2000 family of standards. Data
speed can reach 2.4 Mbit/s with Rev. 0
and up to 3.1 Mbit/s with Rev. A.
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