1. 3GPP Network Architecture Radio Access Technologies Discussion
UMTS vs. LTE: a comparison overview
Unik4230: Mobile Communications
Khai Vuong
May 16, 2011

2. 3GPP Network Architecture Radio Access Technologies Discussion
Agenda
3GPP
Network Architecture
UMTS
LTE
Radio Access Technologies
WCDMA
OFDMA
Discussion

3. 3GPP Network Architecture Radio Access Technologies Discussion
1
3GPP Standards (I)
3GPP: 3rd Generation Partnership Project
Version Released Info
Release 98 1998 specified pre-3G GSM network
Release 99 2000 Q1 specified the first version of UMTS, in-
corporating a CDMA air interface
Release 4 2001 Q2 aka. Release 2000, added all-IP Core
Network
Release 5 2002 Q1 introduced IMS and HSDPA
Release 6 2004 Q4 integrated operation with Wireless LAN
networks and added HSUPA, MBMS,
enhancements to IMS
1
http://en.wikipedia.org/wiki/3GPP

4. 3GPP Network Architecture Radio Access Technologies Discussion
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3GPP Standards (II)
Version Released Info
Release 7 2007 Q4 decreasing latency, improvements
to QoS and real-time applications,
HSPA+ , NFC, EDGE Evolution.
Release 8 2008 Q4 First LTE release. All-IP Network
(SAE), new OFDMA, FDE and MIMO
based radio interface.
Release 9 2009 Q4 SAES Enhancements, Wimax and
LTE/UMTS Interoperability
Release 10 2011 Q1 LTE advanced
2
http://en.wikipedia.org/wiki/3GPP

5. 3GPP Network Architecture Radio Access Technologies Discussion
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3GPP data evolution
3
Huawei Technologies Co., Ltd. 2009

6. 3GPP Network Architecture Radio Access Technologies Discussion
User experience
Type of services UMTS LTE
Web surfing 8 seconds immediately
Download 5MB music 3 minutes 1 second
Download 750MB movie 6.5 hours 2.5 minutes
Download HD video ∼2-3 days ∼15 minutes
√ √
Video telephony
√ √
Corporate VPN, Intranet
√ √
Mobile TV
√
On-demand TV
√
Video-based mobile advertising
√
...
Table: Data services4
4
Huawei Technologies Co., Ltd. 2009

7. 3GPP Network Architecture Radio Access Technologies Discussion
Services for telecommunication systems
1. Teleservice: Information that transfered between end users,
e.g speech service, messaging, emergency calls.
2. Bearer service: Different QoS classes for various type of
traffic:
• Conversasional: voice, video, telephony, video gaming
• Streaming: multimedia, video on-demand, webcast
• Interactive: web browsing, network gaming, database access
• Background: email, SMS, downloading

8. 3GPP Network Architecture Radio Access Technologies Discussion
UMTS objectives
1. improvement in data performance, multimedia services and
access to the Internet
2. new radio interface WCDMA
3. Core Network: connection function

9. 3GPP Network Architecture Radio Access Technologies Discussion
Core Network for UMTS
• MSC:Mobile switching center, switch the CS transactions
• GMSC: Gateway MSC: a switch that connects the UMTS PLMN to the external
CS networks.
• SGSN: Serving GPRS Support Node, similar to MSC/VLR but this is for PS
traffic.
• GGSN: Gateway GPRS Support Node, similar to GMSC but it serves for the PS
traffic.

10. 3GPP Network Architecture Radio Access Technologies Discussion
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LTE’s objectives
1. higher data rates in both downlink and uplink transmission
2. reduce packet latency, more responsive user experience
3. flat architecture: IP-based, open interfaces, simplified network
4. flexible radio planning and high spectral efficiency
5. reduce delivery costs for rich communications
6. long-term revenue stability and growth
7. coexistence alongside circuit switched networks
5
UMTS Forum 2008

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Why LTE?6
GSM EDGE WCDMA HSPA LTE
Non-3GPP technologies
Figure: Flexible upgrade path
Figure: Reduce pris per MB to
remain profitable
6
Nokia Siemens Networks

12. 3GPP Network Architecture Radio Access Technologies Discussion
UMTS vs. LTE Architecture
7
Figure: Network architecture, simplified
LTE: simplified IP flat architecture
• BSC/RNC disappeared, functions transfer to eNodeB
• All eNodeB connect directly through X2 interface
• PS service only, voice over IP.
7
Image courtesy: UMTS Forum 2008

13. 3GPP Network Architecture Radio Access Technologies Discussion
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LTE’s interfaces: S1 and X2
• X2: connects eNodeB
• MME (Mobility
Management Entity):
distribution of paging
message to eNodeB
• UPE (User Plan Entity): IP
header compression,
encryption of user data
stream, termimating and
• S1: self-optimizing network switching of U-plane
8
Image courtesy: developer.att.com

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Wideband CDMA
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Figure: Access technique for UMTS
9
Huawei Technologies Co., Ltd. 2009

15. 3GPP Network Architecture Radio Access Technologies Discussion
CDMA: Principles
• each user is assigned a spreading code for encoding it’s data
• Receiver knows the code of user, it can decode the received
signal, recover the original data
• Bandwidth of coded data signal much larger than original
data signal due to the encoding process spreads the spectrum
of the origianl signal, based on spread-spectrum modulation

16. 3GPP Network Architecture Radio Access Technologies Discussion
WCDMA in UMTS [4]
• Direct Sequence CDMA system, with chip-rate 3.84 Mc/s
• Combined with FDMA: every carrier is allocated 5 MHz
frequency band so that many operators can provide services
without interference each other.
• Codes: scrambling and channelization
Channelization: seperates Scrambling codes: not
traffic to and from different increase bandwidth, but is
users, called Orthogonal used for distinguishing
Variable Spreading Factor terminals in uplink and
(OVSF) which varies from 1 sectors (cells) in downlink
to 128

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LTE’s downlink: OFDMA
OFDM: Multiple access scheme,
allows simultaneous connections
to/from multiple mobile
terminals
Users share different subcarriers,
either consecutive or distributed
manner.

18. 3GPP Network Architecture Radio Access Technologies Discussion
LTE’s uplink: Single Carrier-FDMA
• SC-FDMA: hybrid modulation
scheme that combines the low
PAPR techniques of single-carrier
transmission systems, such as GSM
and CDMA, with the multi-path
resistance and flexible frequency
allocation of OFDMA
• Data symbols in the time domain
are converted to the frequency
domain using a discrete Fourier
transform (DFT)
• Cyclic Prefix (CP) is added, a serial Figure: Structure for UL and DL in
sequence of symbols is modulated LTE [5]
and transmitted instead of parallel
OFDM-scheme
• On receiver’s side, an extra N-point An advantage of SC-FDMA compares to
IDFT is applied to reconstruct the OFDMA is low Peak to Power Average
original symbols. Ratio (PAPR), that helps increasing
battery life.

19. 3GPP Network Architecture Radio Access Technologies Discussion
References
Ville Eerola, LTE Network Architecture Evolution, Lecture
note in T-109.5410 Technology Management in the
Telecommunications Industry, Helsinski University of
Technology, 2010.
UMTS Forum, Toward Global Mobile Broadband, retreived
May 16, 2011from
www.umts-forum.org/component/option,com.../Itemid,12/
M. Neruda and R. Bestak, Evolution of 3GPP Core Network,
IWSSIP 2008.
Lecture notes in UniK 4230, UiO, Lecture9-10.pdf
OFDM(A) for wireless communications, Telenor R&I R 7/2008

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A brief comparision
Requirements UMTS LTE
Spectral Efficiency 0.2bit/s/Hz 1.57bit/s/Hz
Peak Data Rate 2 Mbit/s 170 Mbit/s
Sector Capacity 1 Mbit/s 31.4 Mbit/s
No. of Tranceivers/Cell 30 1
RTT User Plane 50 ms 5 ms
Call setup time 2s 50 ms
Mobility 250 km/h 350 km/h
Bandwidth 5 MHz scalable up to 20 MHz
10
UMTS/HSPA to LTE Migration, Motorola Inc. 2009

21. 3GPP Network Architecture Radio Access Technologies Discussion
Discussion
Point to discuss, focus on this topic, futher questions?