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3GPP Network Architecture Radio Access Technologies Discussion

Agenda

3GPP

Network Architecture

UMTSLTE

Radio Access TechnologiesWCDMAOFDMA

Discussion

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3GPP Standards (I) 1

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 CoreNetwork

Release 5 2002 Q1 introduced IMS and HSDPA

Release 6 2004 Q4 integrated operation with Wireless LANnetworks and added HSUPA, MBMS,enhancements to IMS

1http://en.wikipedia.org/wiki/3GPP

http://en.wikipedia.org/wiki/3GPP


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3GPP Standards (II) 2

Version Released Info

Release 7 2007 Q4 decreasing latency, improvementsto QoS and real-time applications,

HSPA+ , NFC, EDGE Evolution.Release 8 2008 Q4 First LTE release . All-IP Network

(SAE), new OFDMA, FDE and MIMObased radio interface.

Release 9 2009 Q4 SAES Enhancements, Wimax andLTE/UMTS Interoperability

Release 10 2011 Q1 LTE advanced

2http://en.wikipedia.org/wiki/3GPP



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3GPP data evolution 3

3Huawei Technologies Co., Ltd. 2009

G

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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 minutesVideo telephony

√ √

Corporate VPN, Intranet√ √

Mobile TV√ √

On-demand TV √ Video-based mobile advertising

√

...√

Table: Data services4


3GPP N k A hi R di A T h l i Di i

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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

3GPP N t k A hit t R di A T h l i Di i

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UMTS objectives

1. improvement in data performance, multimedia services andaccess to the Internet

2. new radio interface WCDMA

3. Core Network: connection function


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Core Network for UMTS

•MSC:Mobile switching center, switch the CS transactions

• GMSC: Gateway MSC: a switch that connects the UMTS PLMN to the externalCS networks.

• SGSN: Serving GPRS Support Node, similar to MSC/VLR but this is for PStraffic.

• GGSN: Gateway GPRS Support Node, similar to GMSC but it serves for the PS

traffic.


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LTE’s objectives 5

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

5UMTS Forum 2008


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Why LTE?6

Non-3GPP technologies

GSM EDGE WCDMA HSPA LTE

Figure: Flexible upgrade path

Figure: Reduce pris per MB toremain profitable

6Nokia Siemens Networks


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UMTS vs. LTE Architecture

Figure: Network architecture, simplified7

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.7Image courtesy: UMTS Forum 2008


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g

LTE’s interfaces: S1 and X2 8

• S1: self-optimizing network

• X2: connects eNodeB

• MME (MobilityManagement Entity):distribution of pagingmessage to eNodeB

• UPE (User Plan Entity): IPheader compression,

encryption of user datastream, termimating andswitching of U-plane

8Image courtesy: developer.att.com


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Wideband CDMA

Figure: Access technique for UMTS 9



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CDMA: Principles

• each user is assigned a spreading code for encoding it’s data

• Receiver knows the code of user, it can decode the receivedsignal, recover the original data

• Bandwidth of coded data signal much larger than originaldata signal due to the encoding process spreads the spectrumof the origianl signal, based on spread-spectrum modulation


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WCDMA in UMTS [4]

• Direct Sequence CDMA system, with chip-rate 3.84 Mc/s

• Combined with FDMA: every carrier is allocated 5 MHzfrequency band so that many operators can provide serviceswithout interference each other.

• Codes: scrambling and channelization

Channelization: seperatestraffic to and from different

users, called Orthogonal Variable Spreading Factor

(OVSF) which varies from 1to 128

Scrambling codes: notincrease bandwidth, but is

used for distinguishingterminals in uplink andsectors (cells) in downlink


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LTE’s downlink: OFDMA

OFDM: Multiple access scheme,

allows simultaneous connectionsto/from multiple mobileterminalsUsers share different subcarriers,either consecutive or distributed

manner.


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LTE’s uplink: Single Carrier-FDMA

• SC-FDMA: hybrid modulationscheme that combines the lowPAPR techniques of single-carriertransmission systems, such as GSMand CDMA, with the multi-pathresistance and flexible frequency

allocation of OFDMA• Data symbols in the time domain

are converted to the frequencydomain using a discrete Fouriertransform (DFT)

•Cyclic Prefix (CP) is added, a serial

sequence of symbols is modulatedand transmitted instead of parallelOFDM-scheme

• On receiver’s side, an extra N-pointIDFT is applied to reconstruct theoriginal symbols.

Figure: Structure for UL and DL in

LTE [5]

An advantage of SC-FDMA compares toOFDMA is low Peak to Power Average

Ratio (PAPR), that helps increasing

battery life.


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References

Ville Eerola, LTE Network Architecture Evolution, Lecturenote in T-109.5410 Technology Management in the

Telecommunications Industry , Helsinski University of Technology, 2010.

UMTS Forum, Toward Global Mobile Broadband , retreivedMay 16, 2011fromwww.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


http://www.umts-forum.org/component/option,com.../Itemid,12/

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A brief comparision 10

Requirements UMTS LTE

Spectral Efficiency 0.2bit/s/Hz 1.57bit/s/Hz

Peak Data Rate 2 Mbit/s 170 Mbit/sSector Capacity 1 Mbit/s 31.4 Mbit/s

No. of Tranceivers/Cell 30 1

RTT User Plane 50 ms 5 ms

Call setup time 2 s 50 ms

Mobility 250 km/h 350 km/h

Bandwidth 5 MHz scalable up to 20 MHz

10UMTS/HSPA to LTE Migration, Motorola Inc. 2009


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Discussion

Point to discuss, focus on this topic, futher questions?

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