1. 3 G SYSTEMS

2. 3G or IMT-2000
• The 3G features:
– Provision of multirate services
– Packet data
– A user-dedicated pilot for a coherent uplink
– An additional DL pilot channel for beam forming
– Intercarrier handover
– Fast power control
– Multiuser detection

3. • IMT-2000 has published a minimum
performance requirement of a 3G wireless
system, which is for both circuit-switched (CS)
and packet-switched (PS) data:
– Data rate of 144 kbps in the vehicular
environment
– Data rate of 384 kbps in the pedestrian
environment
– Data rate of 2 Mbps in the fixed indoor and pico
cell environment
3G or IMT-2000

4. Near-far Effect
• Traditionally single-user receiver is known suffering
from the so-called near-far problem, where a near-by
or strong signal source may block the signal
reception of far-away or weak user(s).
• The near-far is more serious in CDMA-liked wireless
multi-user communication systems. And multiuser
detection techniques can help the receiver solve this
problem
• Multiuser detection is one of the receiver design
technology for detecting desired signal(s) from
interference and noise.

5. • Consider a receiver and two transmitters, one close
to the receiver, the other far away. If both
transmitters transmit simultaneously and at equal
powers, then due to the inverse square law the
receiver will receive more power from the nearer
transmitter
• Since one transmission's signal is the other's noise
the signal-to-noise ratio (SNR) for the farther
transmitter is much lower
• This makes the farther transmitter more difficult, if
not impossible, to understand
Near-far Effect

6. • If the nearer transmitter transmits a signal that is
orders of magnitude higher than the farther
transmitter then the SNR for the farther transmitter
may be below detectability and the farther
transmitter may just as well not transmit. This
effectively jams the communication channel.
• In short, the near-far problem is one of detecting or
filtering out a weaker signal amongst stronger
signals.
Near-far Effect

7. Pilot Channel
• Pilot Channel/Signal
– provides a phase reference for coherent
demodulation, and provides a means for signal
strength comparisons between base stations for
determining when to hand off.

8. Why standardization?
• standardization important because
interworking is necessary:
– Applications across the network
– Equipment produced by different companies
– Networks of different operators
• hence it is not a good idea for everybody to
develop their own protocols / architectures
• Network Experts sit together develop and
standardize the technology simultaneously

9. • What needs to be standardized? the "Essential
What":
– basic architecture
– functionality of essential network elements
– protocols and protocol stacks
– interfaces
– information storage
– Everything else related to interworking
Why standardization?

10. • What needs not be standardized?
• the "How" and everything not essential:
– internal operation of network elements
– intradomain solutions not related to core
functionality
– e.g. intra-domain resource management
• Equipment vendors / operators have to come
up with own solution for things not
standardized
Why standardization?

11. Why standardization?

12. Wide band CDMA
• In the standardization forums, WCDMA technology
has emerged as the most widely adopted third
generation air interface
• Its specification has been created in 3GPP (the 3rd
Generation Partnership Project), which is the joint
standardization project of the standardization bodies
from Europe, Japan, Korea, the USA and China
• Within 3GPP, WCDMA is called UTRA (Universal
Terrestrial Radio Access) FDD (Frequency Division
Duplex) and TDD (Time Division Duplex), the name
WCDMA being used to cover both FDD and TDD
operation.

13. W-CDMA Contd…
• WCDMA is a wideband Direct-Sequence Code
Division Multiple Access (DS-CDMA) system, i.e. user
information bits are spread over a wide bandwidth
by multiplying the user data with quasi-random bits
(called chips) derived from CDMA spreading codes.
• In order to support very high bit rates (up to 2
Mbps), the use of a variable spreading factor and
multicode connections is supported.

14. • The chip rate of 3.84 Mcps leads to a carrier
bandwidth of approximately 5 MHz.
• DSCDMA systems with a bandwidth of about 1
MHz, such as IS-95, are commonly referred to
as narrowband CDMA systems
• The inherently wide carrier bandwidth of
WCDMA supports high user data rates and
also has certain performance benefits, such as
increased multipath diversity
W-CDMA Contd…

15. Advantages of using WCDMA
• Multiple access capability. Because all users have
different spreading codes, which do not ideally cross-correlate
too much, several users can coexist in the same frequency
band.
• Protection against multipath interference.
Multipath interference is a result of reflections and
diffractions in the signal path. The various component signals
may be interference to each other. A spread spectrum CDMA
signal can resist the multipath interference if the spreading
codes used have good autocorrelation properties.

16. Advantages of using WCDMA
• Good jamming resistance. Because the power
spectral density of the signal is so low and resembles
background noise, it is difficult to detect and jam on
purpose.
• Privacy. An intruder cannot recover the original
signal unless he knows the right spreading code and
is synchronized to it.
• Narrowband interference resistance. A wideband
signal can resist narrowband interference especially
well.

17. WCDMA supports two basic modes of
operation:
• Frequency Division Duplex (FDD)
• Time Division Duplex (TDD)
W-CDMA Contd…

18. Frequency Division Duplex (FDD)
• In the FDD mode, separate 5 MHz carrier frequencies
are used for the uplink and downlink respectively
• Each carrier is divided into 10-ms radio frames, and
each frame further into 15 time slots
• The UTRAN chip rate is 3.84 Mcps meaning every
second, 3.84 million chips are sent over the radio
interface
– A chip is a bit in a code word, which is used to modulate
the information signal. Since they represent no
information by themselves, we call them chips rather than
bits

19. Frequency Division Duplex (FDD)
• The ratio between the chip rate and the data bit rate
is called the spreading factor
• In theory we could have a spreading factor of one,
that is, no spreading at all. Each chip would be used
to transfer one data bit.
• However, this would mean that no other user could
utilize this frequency carrier, and moreover we would
lose many desirable properties of wideband
spreading schemes.

20. Frequency Division Duplex (FDD)
• In principle, the spreading factor indicates how large
a chunk of the common bandwidth resource the user
has been allocated
• For example, one carrier could accommodate at most
16 users, each having a channel with a spreading
factor of 16.
• The spreading factors used in UTRAN can vary
between 4 and 512. A sequence of chips used to
modulate the data bits is called the spreading code.
Each user is allocated a unique spreading code.

21. Time Division Duplex (TDD)
• The TDD mode differs from the FDD mode in
that both the uplink and the downlink use the
same frequency carrier
• The 15 time slots in a radio frame can be
dynamically allocated between uplink and
downlink directions, thus the channel capacity
of these links can be different
• only one 5 MHz is timeshared between the
uplink and downlink

22. Time Division Duplex (TDD)
• The chip rate of the normal TDD mode is also
3.84 Mcps, but there exists also a “narrow
band” version of TDD known as TD-SCDMA
• The carrier bandwidth of TD-SCDMA is 1.6
MHz and the chip rate 1.28 Mcps. TD-SCDMA
can potentially have a large market share in
China

23. W-CDMA
• WCDMA supports the operation of
asynchronous base stations, so that, unlike in
the synchronous IS-95 system, there is no
need for a global time reference such as a GPS
• Deployment of indoor and micro base stations
is easier when no GPS signal needs to be
received

26. • UMTS is the European member of the
IMT2000 family of third generation cellular
mobile standards.
• The goal of UMTS is to enable networks that
offer true global roaming and to support a
wide range of voice, data and multimedia
services
Universal Mobile
Telecommunication Services

27. UMTS Contd..
• Data rates offered by UMTS are:
– vehicular - 144 Kbps
– pedestrian 384 Kbps
– in-building Kbps
• Backward compatibility with 2G networks by
utilizing GSM/GPRS network infrastructure

28. FDD Technical summary
• Frequency band:1920 MHz -1980 MHz and 2110 MHz -
2170 MHz (Frequency Division Duplex) UL and DL
• Minimum frequency band required: ~ 2x5MHz
• Frequency re-use: 1
• Carrier Spacing: 4.4MHz - 5.2 MHz
• Modulation: QPSK
• Pulse shaping: Root raised cosine, roll-off = 0.22
• Receiver: Rake
• Chip rate: 3.84 Mcps
• Channel coding: Convolutional coding, Turbo code for
high rate data

29. TDD Technical Summary
• Frequency band:1900 MHz -1920 MHz and 2010
MHz - 2025 MHz (Time Division Duplex) Unpaired,
channel spacing is 5 MHz and raster is 200 kHz. Tx
and Rx are not separated in frequency, but by guard
period.
• Minimum frequency band required: ~ 5MHz, ~
1.6MHz with 1.28 Mcps
• Frequency re-use: 1
• channel coding: Convolutional coding, Turbo code
for high rate data
• Chip rate: 3.84 Mcps or 1.28 Mcps

30. • 1900-1920 and 2010-2025 MHz Time Division
Duplex (TDD, TD/CDMA) Unpaired, channel
spacing is 5 MHz and raster is 200 kHz. Tx and
Rx are not separated in frequency.
• 1980-2010 and 2170-2200 MHz Satellite
uplink and downlink.
Technical Specs

31. UMTS Network Architecture
• The interfaces between the UE and the UTRAN (Uu
interface) and between the UTRAN and the CN (Iu) are
open multivendor interfaces

32. UMTS Network Architecture

33. UMTS Network Architecture

34. UMTS Network Architecture
A UMTS network consists of three interacting
domains:
• User Equipment (UE):The UE is a mobile that
communicates with UTRAN via the air-interface
• UMTS Terrestrial Radio Access Network
(UTRAN) : UTRAN provides the air interface access
method for the UE
• Core Network (CN):provides switching, routing,
and transit for user traffic. It also stores databases
and provides network management functions.

35. User Equipment (UE)
• A UE consists of two parts:
– The Mobile Equipment (ME) is a radio terminal
used for communicating over the Uu interface (air-
interface).
– The UMTS Subscriber Identity Module (USIM) is a
smartcard that stores subscribers’ identity and
encryption keys, performs authentication
algorithms, and supports subscription information
for the ME

37. UMTS Terrestrial Radio
Access Network (UTRAN)
• A UTRAN consists of two distinct elements: Node B
and Radio Network Controller (RNC)
• The main functions of the UTRAN architecture are to:
– Support soft handoff and W-CDMA specific radio resource
management
– Share and reuse of voice and packet data interfaces (ie. Iu-
CS and Iu-PS)
– Share and reuse of GSM infrastructure
– Use ATM as the main transport mechanism within UTRAN

38. UTRAN Architecture

39. Radio Network Sub-Systems (RNS)
• A UTRAN may consist of one or more Radio
Network Sub-Systems (RNS).
• An RNS is a sub-network within UTRAN that
consists of one RNC and one or more Node B
• RNCs which belongs to different RNS can be
connected to each other via the Iur interface

40. Node B
• A Node B (logically corresponds to the GSM
Base Station) converts data flow between the
Iub and Uu interfaces
• Its main duty is to perform the physical layer
processing, e.g. modulation, coding,
interleaving, rate adaptation, spreading, etc.

41. Radio Network Controller (RNC)
• An RNC (logically corresponds to the GSM Base
Station Controller) controls the radio resources in
its domain
• RNC is the service access point for all services
UTRAN providing to the Core Network
• It also terminates the Radio Resource Control
Protocol (RRC) that defines the messages and
procedures between UE and UTRAN.
• The logical function of an RNC is further divided
into controlling, serving, and drift

42. • The controlling RNC administers the Node B for load
and congestion control. It also executes admission
control and channel code allocation for new radio
links to be established by the Node B.
• Mobility management functions such as power
control, handoff decision, etc are also handled by the
serving RNC. Note that one UE connected to the
UTRAN has one and only one SRNC.
• The drift RNC compliments the serving RNC by
providing diversity when the UE is in the state of
inter-RNC soft handoff (which requires two RNCs).
Radio Network Controller (RNC)

44. Core Network (CN)
• UMTS CN is divided into circuit switched and
packet switched domains.
• ATM is the transport mechanism to be used in
the UMTS core
• The core network consists of the following
elements inherited from the incumbent GSM
network:
– HLR,MSC/VLR,GMSC, SGSN,GGSN

45. Home Location Register
(HLR)
• An HLR is a database located in the user’s
home system that stores the user’s service
profile.
• A service profile is created when a new user
subscribes to the system, and remained as
long as the subscription is active.
• It consists of information such as user service
type and roaming permission etc.

46. (MSC/VLR)
• The co-located MSC/VLR serves as both the
switch and database for the circuit switch
service.
• The MSC is used to switch the circuit switch
data while the VLR function temporarily hold
copies of the visiting users’ service profile.

47. Gateway MSC (GMSC)
• It is the gateway that connects the UMTS
PLMN with the external circuit switch
networks.
• All incoming and outgoing circuit switch
connections go through the GMSC

48. SGSN and GGSN
• SGSN has the similar functionality as MSC/VLR
except it handles packet switch connections
• GGSN has the same functionality as that of
GMSC except it handles the packet switch
connection.

49. GSM Radio Access Network

50. UMTS Evolution
• Layer 2 between RNC and GGSN not
necessarily ATM based
• Flexible RANs
– May attach GSM RAN and GERAN to PS domain
GERAN = GSM EDGE Radio Access Network
• Iu Flex
– Breaking hierarchical mapping of RNCs to SGSNs
(MSCs)

51. • HSDPA (High Speed Downlink Packet Access)
– Can accommodate peek-rates up to 16 Mb/s
– Sustained rates of 1 – 5 Mb/s (depending on cell
size)
– 16QAM modulation used in addition to QPSK
– Turbo Codes
− Powerful error correcting / encoding scheme suited for
low signal-noise ratios
UMTS Evolution

52. CDMA 2000
• CDMA2000 is another wireless standard
designed to support 3G services as defined by
the ITU and its IMT-2000 vision.
• It is evolved from the North American IS-95
CDMA standard.
• CDMA2000 system uses 2.1GHz band and it
maintains backward compatibility by allowing
current frequency bands of 800, 1800 and
1900 MHz to operate seamlessly.

53. Cdma2000 Technical summary
• Frequency band: Any existing band
• Minimum frequency band required: 1x: 2x1.25MHz,
3x: 3x1.25=3.75
• Chip rate: 1x: 1.2288, 3x: 3.6864 Mcps
• Maximum user data rate: 1x: 144 kbps now, 307
kbps in the future 1xEV-DO: max 384 kbps - 2.4
Mbps, 1xEV-DV: 4.8 Mbps.
• Modulation: QPSK (downlink) BPSK(uplink)

54. CDMA Network Architecture

55. • Besides MS and BTS, the first six elements are
the same as in cdmaOne for circuit switched
voice and data service; BSC, MSC, HLR, VLR,
AC, and IWF.
• The IWF enables circuit-switched data service,
and BSC carries out the mobility management.
• The additional two elements are for the
purpose of providing packet-switched data
service.
CDMA Network Architecture

56. • In cdma2000 architecture, mobile station (MS)
gain access to a service provider network via
the air interface to the Radio Network (RN)
• Access mobility management is achieved
using existing air interface procedures that
include interactions with Visited Location
Registers (VLR) and Home Location Registers
(HLR)
CDMA Network Architecture

57. Mobile Station (MS)
• The main function of the MS is to establish, maintain,
and terminate voice and data connections through
the PDSN
• The MS establishes a connection by requesting the
appropriate radio resources from the RN. Once the
connection is established, the mobile station is
responsible for maintaining knowledge of radio
resources, buffering packets from the mobile
applications when radio resources are not in place or
are insufficient to support the flow to the network.

58. Radio Network (RN)
• The Radio Network consists of two logical
components:
• Packet Control Function (PCF)
• Radio Resources Control (RRC).

59. Packet Control Function (PCF)
• The primary function of the PCF is to establish,
maintain, and terminate L2 connection to the PDSN. It
also communicates with the RRC to request and
manage radio resources in order to relay packets to
and from the mobile station
• During hard handoff to another RRC, the serving PCF
forwards its information to the target PCF to re-
establish packet data session to the PDSN
• Finally PCF is responsible for collecting accounting
information and forward them to the PDSN

60. Radio Resources Control (RRC)
• RRC supports authentication and
authorization of the mobile station for radio
access.
• It also supports air interface encryption to the
mobile station.

61. Packet Data Serving Node
(PDSN)
• Key functionalities of PDSN are:
– Routing packets to the IP networks or directly to
the HA is the major effort of PDSN
– It assigns dynamic IP addresses and maintains PPP
sessions to the mobile stations
– Similar in function to the GGSN (GPRS Gateway
Support Node) that is found in GSM and UMTS
networks.

62. Home Agent (HA)
• The HA is a router that resides on that MS’ home IP
network.
• Home Agent (HA) plays a major role in implementing
the Mobile IP protocol by redirecting packets to the
Foreign Agent (FA), and receive and route reverse
tunneled packets from the FA
• HA provides security by authenticating mobile
station through Mobile IP registration.
• HA also maintains direct connection with AAA in
order to receive provisioning information for
subscribers

63. • This is another router residing in another
PDSN.
• When an MS visits a foreign IP network, the FA
on the foreign network receives packets
forwarded from the HA and delivers them to
the MS.
Foreign Agent (FA)

64. Authentication, Authorization,
and Accounting (AAA)
• pass authentication requests from the PDSN to the
home IP network, and authorize responses from the
home IP network to the PDSN
• Stores accounting information for the MS and
provides user profiles and QOS information to the
PDSN.
• An AAA server connected to a home IP network
authenticates and authorizes the mobile station
based on requests from the local AAA.

65. 3G Evolution of CDMA2000
• The 3G Evolution of CDMA2000 means the
evolution of CDMA 1X to CDMA 1xEV-DO and
CDMA2000 1xEV-DV
– CDMA2000 1x EV-DO (DO= Data Only)
– CDMA2000 1xEV-DV(DV=Data and Voice)
• CDMA2000 1X can double the voice capacity
of CdmaOne networks and delivers peak
packet data speeds of 307 kbps in mobile
environments

66. Voice
Data up to
14.4 Kbps
Voice data up
to 115 Kbps
2x increases in voice capacity
Up to 307 Kbps packet data on
single carrier in downlink
First 3G system for any
technology worldwide.
Optimized for
very high data
speed (phase 1).
Up to 2.4Mbps
packet data on
single carrier
Integrated voice
and data (phase 2)
Up to 3.08 Mbps.

67. Thank You!
67