2. cience and technology of communication over a distance.
he ability to convey information quickly accurately and efficiency
as been one of the main focuses driving human innovation.
Telecommunication:
Cellular network:
Base stations transmit to and receive from mobiles at the
assigned spectrum
Multiple base stations use the same spectrum (spectral reuse)
The service area of each base station is called a cell
Each mobile terminal is typically served by the ‘closest’ base
stations
Wireless:
Term used to describe any computer network where there
Is no physical wired connection between sender and receiver.
3. CELLULAR NETWORKS: FROM 0G
TO 5G
0G: Briefcase-size mobile radio telephones
1G: First generation wireless cellular: Early 1980s
Analog transmission, primarily speech: AMPS (Advanced Mobile Phone
Systems) and others
2G: Second generation wireless cellular: Late 1980s
Digital transmission
Primarily speech and low bit-rate data (9.6 Kbps)
High-tier: GSM, IS-95 (CDMA), etc
Low-tier (PCS): Low-cost, low-power, low-mobility e.g. PACS
2.5G: 2G evolved to medium rate (< 100kbps) data
3G: future Broadband multimedia
144 kbps - 384 kbps for high-mobility, high coverage
2 Mbps for low-mobility and low coverage
4G: IP-based “anytime, anywhere” voice, data, and
multimedia telephony at faster data rates than 3G
Beyond 4G: research in 5G
Overview:
4. Mobile radio telephones were used for military communications
in early 20th century
Car-based telephones first introduced in mid 1940s
Single large transmitter on top of a tall building
Single channel used for sending and receiving
To talk, user pushed a button, enabled transmission and disabled
reception
Became known as “push-to-talk” in 1950s
CB-radio, taxis, police cars use this technology
IMTS (Improved Mobile Telephone System) introduced in 1960s
Used two channels (one for sending, one for receiving)
No need for push-to-talk
Used 23 channels from 150 MHz to 450 MHz
0G TECHNOLOGY
5. 1G TECHNOLOGY
Advanced Mobile Phone Service (AMPS) invented at Bell
Labs and first installed in 1982
Its speed was up to 2.4kbps
It use analog signal
It allows the voice calls in 1 country.
Drawbacks:
Poor voice quality
Large phone size
Limited capacity
poor battery life
Poor handoff reliability
6. SECURITY ISSUES WITH 1G
Analog cellular phones are insecure
Anyone with an all band radio receiver can
listen in (many scandals)
Theft of airtime:
all band radio receiver connected to a computer
can record 32 bit serial number and phone number of
subscribers when calling
can collect a large database by driving around
Thieves go into business - reprogram stolen phones and
resell them
7. Based on digital transmission means convert analog to
digital.
Based on GSM(Global system for mobile communication)
Launched in 1991
Sped up to 64kbps.
2G TECHNOLOGY
Features include:
Enables services such as text messages, pic messages and MMS
Provides better quality and capacity.
Drawbacks:
These system are unable to handle complex data such as video
2G requires digital signal to help mobile phone work.
8. GSM (GLOBAL SYSTEM FOR MOBILE
COMMUNICATIONS)
Completely designed from scratch (no backward
compatibility)
Uses 124 channels per cell, each channel can support 8
users through TDM (992 users max)
Some channels used for control signals, etc
Several flavors based on frequency:
GSM (900 MHz)
GSM 1800 (called DCS 1800)
GSM 1900 (called DCS 1900) - used in North America
GSM 1900 phone only works in North America.
In Europe, you can transfer your SIM (Subscriber
Identity Module) card to a phone of the correct frequency.
This is called SIM-roaming.
9. GSM (2G-TDMA)
Circuit mode data
Transparent mode
Non-transparent mode using radio link protocol
Data rate up to 9.6kb/s
Short message service
Limited to 160 characters
Packet mode data: Plans for GSM Phase 2+
Architecture specification very detailed (500 pages)
Defines several interfaces for multiple suppliers
10. Its between 2G and 3G of mobile communication.
2G cellular technology combined with GPRS
(general packet radio service).
GPRS -Launched in 1997
It offers 110kbps.
2.75G technology
2.5G technology:
Replace GPRS by EDGE
EDGE-introduced in 2003.
(Enhanced Data rates for GSM Evolution)
All are see E symbol in above SIM representation
It offers 170kbps.
11. IS-95
It is alternative of 2G technology.
Developed by QUALCOMM.
It offers 14kbps.
After improvement of cellular service in large-scale of
2G technology changed into GPRS.
GPRS is used in 2.5G that already known.
Simple word in 2G called =GSM+
GPRS+
EDGE
12. 3G TECHNOLOGY(WCDMA)
ITU introduce 3G specification with IMT-2000
EDGE technology also joined in this technology
but not for long time.
It offers 144kbps to 2mbps.
It increased its bandwidth and data transfer rates.
Features include:
Faster communication.
Video calling.
3D gamming
TV streaming/phone calls/mobile TV
11 sec-1.5min. Time to download a 3min mp3 song.
13. CDMA 200
Alternative of 3G technology
It offers 153kbps
EV-DO next version of CDMA
EV-DO
REV-O REV-A REV-B
Offers 2.4mbps Offers 3.1mbps 10mbps
UMTS-offers only 384kps
Next version of UMTS is HSDPA
HSDPA-offers up to 21mbps
Alternative of EV-DO
14. 3.5G TECHNOLOGY
High Speed Packet Access (HSPA) is an amalgamation of
two mobile telephony protocols, High Speed Downlink
Packet Access (HSDPA) and High Speed Uplink Packet
Access (HSUPA), that extends and improves the performance
of existing WCDMA protocols
3.5G introduces many new features that will enhance the
UMTS technology in future. 1xEV-DV already supports most
of the features that will be provided in 3.5G. These include:
- Adaptive Modulation and Coding
- Fast Scheduling
- Backward compatibility with 3G
- Enhanced Air Interface
15. 4G TECHNOLOGY(LTE)
LTE stands for Long Term Evolution
Next Generation mobile broadband
technology
Promises data transfer rates of 100
Mbps
Based on UMTS 3G technology
Optimized for All-IP traffic
16. 5G TECHNOLOGY
5G is the short for fifth generation, a mobile
broadband technology that is in the early
stages of works and likely to be in place six to
seven years from now.
A 5G network will be able to handle 10,000
times more call and data traffic than the
current 3G or 4G network.
Data download speeds on 5G networks are
likely to be several hundred times more than
4G.
5G mobile technology will change the
means to use cell phones within very high
bandwidth.
17. BRIEF IDEA ABOUT 5G
CURRENT STATUS OF 5G?
The European Telecommunications Standards Institute is
formulating 5G global technology standards, which are likely to
be formalized by 2019.
Telecom companies such as Nokia, Ericsson, NTT DoCoMo,
Samsung, Huawei and Fujitsu are driving bulk of the 5G-
related innovations.
PEOPLE WILL BE ABLE TO EXPERIENCE WITH 5G.
5G networks are likely to be rolled out commercially
between 2020 and 2025. If the global standards are finalized by
2019, the earliest commercial deployments could happen by
2020.
3G AND 4G HANDSETS DOESN’T RUN ON 5G
NETWORKS.
No. 5G will require new chipsets and devices capable
of supporting speeds upwards of 10 gigabits per second. 4G and
3G run at a fraction of that speed.
18. It is the next major phase of mobile
telecommunication & wireless system.
It is 10 times more faster than 4G.
It has a expected speed of 1gbps.
Lower cost than the previous version.
It is expected to come around the year 2017
5G CONT….
20. E
A
DF
G C
B
E
A
DF
G C
B
E
A
DF
G C
B
Cell Design
•Cells grouped into a cluster of seven
•Letters indicate frequency use
•For each frequency, a buffer of two cells is used before reuse
•To add more users, smaller cells (microcells) are used
•Frequencies may not need to be different in CDMA (soft handoff)
21. CELLULAR NETWORK
ORGANIZATION
Cell design (around 10 mile radius)
Served by base station consisting of transmitter,
receiver, and control unit
Base station (BS) antenna is placed in high places (churches,
high rise buildings) -
Operators pay around $500 per month for BS
10 to 50 frequencies assigned to each cell
Cells set up such that antennas of all neighbors are
equidistant (hexagonal pattern)
In North America, two 25-MHz bands allocated
to AMPS
One for transmission from base to mobile unit
One for transmission from mobile unit to base
22. APPROACHES TO INCREASE
CAPACITY
Adding/reassigning channels - some channels are not
used
Frequency borrowing – frequencies are taken from
adjacent cells by congested cells
Cell splitting – cells in areas of high usage can be
split into smaller cells
Microcells – antennas move to buildings, hills, and
lamp posts
23.
24.
25.
26. DIFFERENCES BETWEEN FIRST
AND SECOND GENERATION
SYSTEMS
Digital traffic channels – first-generation
systems are almost purely analog; second-
generation systems are digital
Encryption – all second generation
systems provide encryption to prevent
eavesdropping
Error detection and correction – second-
generation digital traffic allows for
detection and correction, giving clear voice
reception
Channel access – second-generation
systems allow channels to be dynamically
shared by a number of users
27. INTEGRATING DATA OVER
CELLULAR
Direct access to digital channel
Voice and data using one handset
PCS 1900 (GSM-1900)
9.6 kbps circuit switched data
14.4 kbps under definition
Packet mode specified
Short message service
IS-95-based CDMA
13 kbps circuit switched data
Packet mode specified
Short message service
28.
29.
30.
31.
32.
33.
34. MOBILE STATION AND BASE STATION
SUBSYSTEM (BSS)Mobile station
Mobile station communicates across Um interface (air
interface) with base station transceiver in same cell as mobile
unit
Mobile equipment (ME) – physical terminal, such as a
telephone or PCS
ME includes radio transceiver, digital signal processors and
subscriber identity module (SIM)
GSM subscriber units are generic until SIM is inserted
SIMs roam, not necessarily the subscriber devices
BSS
BSS consists of base station controller and one or more base
transceiver stations (BTS)
BSC reserves radio frequencies, manages handoff of mobile
unit from one cell to another within BSS, and controls paging
35. NETWORK SUBSYSTEM CENTERMobile Switching Center (MSC) is at core; consists of
several databases
Home location register (HLR) database – stores
information about each subscriber that belongs to it
Visitor location register (VLR) database –
maintains information about subscribers currently
physically in the region
Authentication center database (AuC) – used for
authentication activities, holds encryption keys
Equipment identity register database (EIR) – keeps
track of the type of equipment that exists at the
mobile station
36. GSM LOCATION SERVICES
Public
Switched
Telephone
Network
(PSTN)
Gateway
MTSC
VLR HLR
Terminating
MSC 1
1. Call made to mobile unit (cellular phone)
2. Telephone network recognizes number
and gives to gateway MSC
3. MSC can’t route further, interrogates
user’s HLR
4. Interrogates VLR currently serving user
(roaming number request)
5. Routing number returned to HLR and
then to gateway MSC
2
3
4
5
5
6
6. Call routed to terminating MSC
7. MSC asks VLR to correlate call to
the subscriber
8. VLR complies
9. Mobile unit is paged
10. Mobile unit responds, MSCs convey
information back to telephone
7 8
9
BTS
9 10
10
10 10
10
Legend: MTSC= Mobile Telephone Service Center, BTS = Base Transceiver Station
HLR=Home Location Register, VLR=Visiting Location Register
37. GSM PROTOCOL ARCHITECTURE
BSSMAP = BSS Mobile Application part
BTSM = BTS management
CM = Connection Management
LAPD = Link Access Protocol, D Channel
Base Transceiver
Station
Mobile
Station
Radio
LAPDm
RRM
Radio
LAPDm
RRM
MM
CM
64 Kbps
LAPD
BTSM
64 Kbps
MTP
SCCP
Base Station
Controller
64 Kbps
LAPD
BTSM
BSSMAP
64Kbps
MTP
SCCP
MM
CM
BSSMAP
Mobile Service
Switching Center
MM = Mobility Management
MTP = Message Transfer Part
RRM = Radio Resources Management
SCCP = Signal Connection Control Point
38. FUNCTIONS PROVIDED BY
PROTOCOLS
Protocols above the link layer of the GSM signaling
protocol architecture provide specific functions:
Radio resource management: controls setup,
termination and handoffs of radio channels
Mobility management: location and security (MTSO)
Connection management: connects end users
Mobile application part (MAP): between HLR,VLR
BTS management: management base system
39. 2G CDMA CELLULAR
IS-95 is the best known example of 2G with CDMA
Advantages of CDMA for Cellular
Frequency diversity – frequency-dependent
transmission impairments have less effect on
signal
Multipath resistance – chipping codes used for
CDMA exhibit low cross correlation and low
autocorrelation
Privacy – privacy is inherent since spread
spectrum is obtained by use of noise-like
signals
Graceful degradation – system only gradually
degrades as more users access the system
40. DRAWBACKS OF CDMA CELLULAR
Self-jamming – arriving transmissions from
multiple users not aligned on chip
boundaries unless users are perfectly
synchronized
Near-far problem – signals closer to the
receiver are received with less attenuation
than signals farther away
Soft handoff – requires that the mobile
acquires the new cell before it relinquishes
the old; this is more complex than hard
handoff used in FDMA and TDMA schemes
41. TYPES OF CHANNELS SUPPORTED
BY FORWARD LINK
Pilot (channel 0) - allows the mobile unit
to acquire timing information, provides
phase reference and provides means for
signal strength comparison
Synchronization (channel 32) - used by
mobile station to obtain identification
information about cellular system
Paging (channels 1 to 7) - contain
messages for one or more mobile stations
Traffic (channels 8 to 31 and 33 to 63) –
the forward channel supports 55 traffic
channels
42. FORWARD TRAFFIC CHANNEL
PROCESSING STEPS Speech is encoded at a rate of 8550 bps
Additional bits added for error detection
Data transmitted in 2-ms blocks with forward error
correction provided by a convolutional encoder
Data interleaved in blocks to reduce effects of errors
Data bits are scrambled, serving as a privacy mask
Power control information inserted into traffic channel
DS-SS function spreads the 19.2 kbps to a rate of 1.2288
Mbps using one row of 64 x 64 Walsh matrix
Digital bit stream modulated onto the carrier using
QPSK modulation scheme
47. ALTERNATIVES TO 3G CELLULAR
Major technical undertaking with many
organizational and marketing overtones.
Questions about the need for the additional
investment for 3G (happy with 2.5G)
Wireless LAN in public places such as shopping
malls and airports offer options
Other high-speed wireless-data solutions
compete with 3G
Mobitex low data rates (nominally 8 Kbps), it uses a narrowband
(2.5KHz) as compared to 30 KHz (GSM) and 5 MHz (3G).
Ricochet: 40 -128 kbps data rates. Bankruptcy
Flash-OFDM: 1.5 Mbps (upto 3 Mbps)
48. MAJOR MOBILE RADIO
STANDARDS
USA
Standard Type Year
Intro
Multiple
Access
Frequency
Band
(MHz)
Modulation Channe
l
BW
(KHz)
AMPS Cellular 1983 FDMA 824-894 FM 30
USDC Cellular 1991 TDMA 824-894 DQPSK 30
CDPD Cellular 1993 FH/Packet 824-894 GMSK 30
IS-95 Cellular/PCS 1993 CDMA 824-894
1800-2000
QPSK/BPSK 1250
FLEX Paging 1993 Simplex Several 4-FSK 15
DCS-1900
(GSM)
PCS 1994 TDMA 1850-1990 GMSK 200
PACS Cordless/PC
S
1994 TDMA/FDMA 1850-1990 DQPSK 300
49. MAJOR MOBILE RADIO
STANDARDS - EUROPE
Standard Type Year
Intro
Multiple
Access
Frequency
Band
(MHz)
Modulation Channe
l
BW
(KHz)
ETACS Cellular 1985 FDMA 900 FM 25
NMT-900 Cellular 1986 FDMA 890-960 FM 12.5
GSM Cellular/PCS 1990 TDMA 890-960 GMSK 200KHz
C-450 Cellular 1985 FDMA 450-465 FM 20-10
ERMES Paging 1993 FDMA4 Several 4-FSK 25
CT2 Cordless 1989 FDMA 864-868 GFSK 100
DECT Cordless 1993 TDMA 1880-1900 GFSK 1728
DCS-1800 Cordless/PC
S
1993 TDMA 1710-1880 GMSK 200
51. 4G SYSTEMS
Wireless networks with cellular data rates of 20
Mbits/second and beyond.
AT&T has began a two-phase upgrade of its wireless
network on the way to 4G Access.
Nortel developing developing features for Internet
protocol-based 4G networks
Alcatel, Ericsson, Nokia and Siemens found a new
Wireless World Research Forum (WWRF) for research
on wireless communications beyond 3G.
Many new technologies and techniques (multiplexing,
intelligent antennas, digital signal processing)
Industry response is mixed (some very critical)
52. ENGINEERING ISSUES
Steps in MTSO controlled call
TDMA design
CDMA design
Handoff
Power control
Traffic engineering
53. STEPS IN AN MTSO CONTROLLED
CALL BETWEEN MOBILE USERS
Mobile unit initialization
Mobile-originated call
Paging
Call accepted
Ongoing call
Handoff
Call blocking
Call termination
Call drop
Calls to/from fixed and remote mobile subscriber
54. MOBILE WIRELESS TDMA DESIGN
CONSIDERATIONS
Number of logical channels (number of
time slots in TDMA frame): 8
Maximum cell radius (R): 35 km
Frequency: region around 900 MHz
Maximum vehicle speed (Vm):250 km/hr
Maximum coding delay: approx. 20 ms
Maximum delay spread (∆m): 10 µs
Bandwidth: Not to exceed 200 kHz (25
kHz per channel)
55. MOBILE WIRELESS CDMA DESIGN
CONSIDERATIONS
Soft Handoff – mobile station temporarily
connected to more than one base station
simultaneously
RAKE receiver – when multiple versions
of a signal arrive more than one chip
interval apart, RAKE receiver attempts to
recover signals from multiple paths and
combine them
This method achieves better performance than
simply recovering dominant signal and
treating remaining signals as noise
56. WHAT IS WIMAX?
Worldwide Interoperability for Microwave
Access
Last mile wireless broadband access
Alternative to cable and DSL
Deliver data, voice, video
Support hundreds to thousands of
homes/business
57. Defined by IEEE as 802.16
Typical target environment:
Targets fixed, portable, and mobile stations
Environments with and without line of sight
Cell radius of 3-10 kilometers
Capacities of up to 40 Mbps per channel
Mobile network deployments of up to 15 Mbps, 3
km radius
58. BUILDS ON AND
EXTENDS WIFI TECHNOLOGY
Advantages of WiFi are:
Easy to deploy, unlicensed spectrum, low
cost
Supports (limited) mobility
But WiMax needs to address the following:
59. WIFI LIMITATIONS
Susceptible to interference
802.11 targets short-range indoor operation
(mostly)
Security is a concern
Limited level of mobility
WiMax is intended to complement WiFi
WiMax Forum: promotes WiMax and looks
after interoperability
61. ADVANTAGES OF DIGITAL
COMMUNICATIONS FOR
WIRELESS
Voice, data and fax can be integrated into a
single system
Better compression can lead to better channel
utilization
Error correction codes can be used for better
quality
Sophisticated encryption can be used