mobile technology session

Mobile Technologies
Overview

Eng.Abdallah Mahmoud
01005303717 abdulluhm@gmail.com

Our Trainers
 Motorola Certified Instructors [For
Theoretical parts].

 Experienced Engineers [For Practical
parts].


Our Trainees
 Our Employees.
 Our Customers.

 External Customers.

 College Students.


Life Before Wireless
Communications
 No need for any Communication
Systems.
 Simple Communication System.

 Wired Telecommunication System
1. Traffic .
2. Signaling .

3. Circuit switching Technology .

 Toward Wireless Communication.


Wireless Comm. Vision
 Mobility .

 Efficiency .

 Cost & Revenue.


Random Access Tech.


Wireless Comm. Challenges
 MultiPath Fading.
 Doppler Shift.

 Diversity.
 Frequency hopping.

 Synchronizations (time & Freq. ).

 Error Protection.


Cellular Mobile Telephony
 Antenna diversity
 Cellular concept
 Frequency reuse
● typically every 7 cells
 Handoff as caller
moves
 Modified CO switch
● HLR, paging
 Sectors improve
reuse
● every 3 cells possible

Origins of Wireless
Communications
 1864: James Clark Maxwell
● Predicts existence of radio waves
 1886: Heinrich Rudolph Hertz
● Demonstrates radio waves
 1895-1901: Guglielmo Marconi
● Demonstrates wireless communications over
increasing
distances
 Also in the 1890s
● Nikola Tesla, Alexander Stepanovich Popov,
Jagdish
Chandra Bose and others, demonstrate forms of
wireless communications Eng.Abdallah Mahmoud

First Mobile Radio
Telephone, 1924


First Generation (nearly all retired)
 Advanced Mobile Phone Service (AMPS)
US trials 1978; deployed in Japan (’79) & US
(’83)
800 MHz; two 20 MHz bands; TIA-553
 Nordic Mobile Telephony (NMT)
Sweden, Norway, Demark & Finland
Launched 1981
450 MHz; later at 900 MHz (NMT900)
 Total Access Communications System
(TACS)
British design; similar to AMPS; deployed 1985

2nd Generation “2G” – digital
systems
 Leverage technology to increase capacity
● Speech compression; digital signal processing
 Utilize/extend “Intelligent Network” concepts
● Improve fraud prevention; Add new services
 Wide diversity of 2G systems
● IS-54/ IS-136 North American TDMA(D-AMPS ); &
PDC (Japan)[PDC dominant 2G cellular system in
Japan].
● DECT and PHS; iDEN
● IS-95 CDMA (cdmaOne)
● GSM


GSM – Global System for
Mobile


GSM – Global System for
Mobile
 Originally “Groupe Spécial Mobile ”
● joint European effort beginning in 1982 focused
on seamless roaming across Europe
Services launched 1991
● time division multiple access (8 users per 200KHz)
● 900 MHz band; later extended to 1800 MHz; then 1900
MHz
● Quad-band “world phones” support 850/900/1800/1900
MHz
 GSM – dominant world standard today
● well defined interfaces; many competitors; lowest cost to
deploy
● network effect (Metcalfe’s law) took hold in late 1990s


1G – Separate Frequencies


2G – Time Division Multiple Access
(TDMA)


2G & 3G – Code Division Multiple
Access
 Spread spectrum modulation
● originally developed for the military
● resists jamming and many kinds of
interference
● coded modulation hidden from those w/o the
code
 All users share same (large) block of
spectrum
● one for one frequency reuse
● soft handoffs possible
 All 3G radio standards based on CDMA
● CDMA2000, W-CDMA and TD-SCDMA Eng.Abdallah Mahmoud

The 3G Vision
 Universal global roaming (1 standard, not 7)
● 3GSM leads, but with CDMA 2000 &
 China TD-SCDMA
 Multimedia (voice, data & video)
 Increased data rates (384 Kbps to ? Mbps)
 Increased capacity (more spectrally efficient)
 Data-centric architecture (ATM at first, then IP)
 But deployment took longer than expected
● No killer data app; new spectrum costly;
 telecom bubble burst; much of the vision was
vendor-driven


GPRS - 2.5G for GSM
- General packet radio service
● first introduction of packet technology
- Aggregate radio channels
● support higher data rates (115 Kbps)
● subject to channel availability
- Share aggregate channels among multiple
users
- All new IP-based data infrastructure
- No changes to voice network

3G Standardization
 ITU (International Telecommunication Union)
● Radio standards and spectrum
 IMT-2000
● ITU’s umbrella name for 3G which stands for
 International Mobile Telecommunications 2000
 3G Partnership Projects (3GPP & 3GPP2)
● focused on evolution of access and core networks
● National and regional standards bodies
collaborating,
i.e., ARIB, TIA, TTA, TTC, CWTS. T1, ETSI


3G Radio technology deployed
today
 EDGE – GSM evolution, i.e. TDMA
● Legacy; sometimes referred to as 2.75G
 CDMA 2000 – Multi Carrier CDMA
● Evolution of IS-95 CDMA
 UMTS/3GSM (W-CDMA, HSPA) – Direct Spread
CDMA
● Defined by 3GPP
 TD-SCDMA – Time Division Synchronous CDMA
● Defined by Chinese Academy of Telecommunications
 Technology under the Ministry of Information Industry
 Paired spectrum bands
 Single spectral band with time division duplexing


UMTS (3GSM) now market
leader
 GSM evolution path: W-
CDMA, HSDPA, HSPA, …
● leverages GSM’s dominant position
 Legally mandated in Europe and elsewhere

● 5 MHz each way (symmetric)
 Requires substantial new spectrum

 Slow start (behind CDMA 2000) but now
leading
● Network effect builds on GSM’s 80% market
share Eng.Abdallah Mahmoud

Diverse Mobile Wireless
Spectrum


Migration Paths


3.5G and 4G
- 4G not formally defined, projected to provide
● 100 Mbps (moving) & 1 Gbps (stationary)
● Seamless roaming across heterogeous
networks
- Pre-4G standards sometimes promoted as
“4G”
● WiMAX – ~6 million units by 12/2008?
● Flash-OFDM - ~13 million subscribers in
2010 ?
● 3GPP Long Term Evolution (LTE) – 2010
launch Eng.Abdallah Mahmoud

LTE highlights
Sophisticated multiple access schemes
● DL: OFDMA with Cyclic Prefix (CP)
● UL: Single Carrier FDMA (SC-FDMA) with CP
Adaptive modulation and coding
● QPSK, 16QAM, and 64QAM
● 1/3 coding rate, two 8-state constituent
encoders, and a
contention-free internal interleaver
Advanced MIMO spatial multiplexing
techniques
● (2 or 4) x (2 or 4) downlink and uplink

4G Technology – OFDMA
Orthogonal Frequency Division Multiple
Access
● Supercedes CDMA used in all 3G variants
OFDMA = Orthogonal Frequency Division
Multiplexing (OFDM) plus statistical
multiplexing
● Optimization of time, frequency and code
multiplexing
Already deployed in 802.11a & 802.11g WiFi

OFDM – Orthogonal Frequency
Division Multiplexing
● Many closely-spaced sub-carriers, chosen
to be orthogonal, thus
eliminating cross-talk & guard bands
● Vary bits per sub-carrier based on
instantaneous received power


Statistical Multiplexing (in
OFDMA)
- Dynamically allocate user data to sub-carriers
based on instantaneous data rates and
varying sub-carrier capacities
- Highly efficient use of spectrum
- Robust against fading, e.g. during mobile
operation


4G Technology - MIMO
-Multiple Input Multiple Output smart
antenna technology
-Multiple paths improve link reliability and
increase spectral efficiency (bps per Hz),
range and directionality


4G Technology – SC-FDMA
- Single carrier multiple access
● Used for LTE & UMB uplinks
● Being considered for 802.16m uplink
- Similar structure and performance to OFDMA
● Single carrier modulation with DFT-spread
orthogonal frequency multiplexing and FD
equalization
- Lower Peak to Average Power Ratio (PAPR)
● Improves cell-edge performance
● Transmit efficiency conserves handset
battery life

Mobile Generations Arch.
Evolving
Advantages for subscriber:
• Mobility
• Flexibility
• Convenience

Advantages for provider:
•Efficiency
• Revenue / profit margins
• Easier for re-configuration
• Network expansion
flexibility


IMT-2000 Vision (from 1992)
included
LAN, WAN and Satellite Services


A2
Frequency reuse A1 A
A3 D2

B2
D1 D
D3 A2
B1 B A1 A
B3 C2 A3 D2
C1 C D1 D
A2 C3 B2 D3
A1 A B1 B
A3 D2 B3 C2

B2
D1 D C1 C
D3 C3
B1 B
B3 C2
C1 C
4 site / 3 cell frequency re-use C3
pattern:

01005303717
abdulluhm@gmail.com

Typical 2G Mobile Architecture


Hand Over
Mobile is handed over from serving cell
to neighbor cell
BT
BT S
S
BT
BSC BT S
XCDR S
BT BT
S BSC BT S
XCDR S
BT BT
S BT
S
BT S
BT S
S

PSTN MSC MSC Eng.Abdallah Mahmoud

Separation of Signaling &
Transport
- Like PSTN, 2G mobile networks have one network
plane for
voice circuits and another network plane for
signaling
- Some elements reside only in the signaling plane
● HLR, VLR, SMS Center, …


Signaling in Core Network
- Based on SS7
● ISUP and specific Application Parts
- GSM MAP and ANSI-41 services
● mobility, call-handling, O&M, authentication,
supplementary services, SMS, …
- Location registers for mobility management
● HLR: home location register has permanent
data
● VLR: visitor location register – local copy for
roamers

PSTN-to-Mobile Call


2.5G/3G Adds IP Data – voice
unchanged


2.5G Architectural Detail


EDGE
Enhanced Data rates for Global Evolution
Increased data rates with GSM compatibility
● still 200 KHz bands; still TDMA
● 8-PSK modulation: 3 bits/symbol give 3X data rate
● shorter range (more sensitive to
noise/interference)
Migration path: IS-136 TDMA to GSM/EDGE
● GAIT - GSM/ANSI-136 interoperability team
● Allowed operators like AT&T and Cingular to
migrate to
GSM/EDGE using an evolved ANSI-41 core network

3G rel99 Architecture (UMTS) - 3G
Radios


3G rel4 Architecture (UMTS) - Soft
Switching


3GPP rel5 Architecture - IP
Multimedia


3G Partnership Project (3GPP)
 Defines migration from GSM to UMTS/
3GSM

W-CDMA – Wideband CDMA modulation
HSxPA – High Speed (Download/Upload) Packet Access
MBMS – Multimedia Broadcast Multicast Service
GAN – Generic Access Network
PoC – Push-to-talk over Cellular Eng.Abdallah Mahmoud
LTE – Long Term Evolution, a new air interface based on OFDM modulation

IMS / NGN Vision
One core network for “any access”
● Based on IP
● Wireline and wireless transparency
● Based on IETF standards, with extensions
Access and bandwidth will be commodities;
services are the differentiator
● Per-session control supports per-application
quality of
service (QoS) guarantees and per-application billing
Voice is just application
● “Easily” integrated with other applications…

IMS Story: Convergence


IMS / NGN Value Proposition
- Generate new revenue from new services
● Per-session control allows IMS to
guarantee QoS for each IP session, and
enables differential billing for applications
& content
- Reduce capital spending
● Converge all services on common
infrastructure
● Focus limited resources on core
competencies Eng.Abdallah Mahmoud

IMS Session (i.e. Call) Control


So far, only for New Applications
!
- Most major mobile operators have deployed a
SIP
infrastructure of some sort
● CSCFs per strict IMS or otherwise
● In use for new applications like Push to Talk
(PTT)
- Fixed operators moving to softswitches for
conventional voice, but
Mobile voice calls still use circuit switching

01005303717
abdulluhm@gmail.com

mobile technology session

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