1. Technology training (Session 1)
Long Term Evolution
Technology training
(Session 1)

2. Outline Goals and schedule Cellular systems (market overview)
Fundamental concepts
Targets for 4G - LTE

3. Cellular service worldwide
Cellular telephony – fastest adoption rate in history of humanity
At the end of 2014
Global penetration of 97%
More than 7B subscribers
Growth driven by developing countries
105 countries with more mobile subscriptions than inhabitants
Fastest growing segment of cellular systems – mobile broadband
More than 2B wireless broadband subs
Note: ITU publishes stats for previous year in June of following year

4. Standardization of cellular technologies
Cellular technology – mass market, high value technology
Development – very standardized
Standardization focuses on three aspects
Network architecture, nodes
Interfaces between nodes
Services offered and inoperability with other networks
Standardization groups organized regionally and globally
Participants are:
Governments
Infrastructure vendors (chipsets, equipment, firmware, software, etc.)
Service providers
Test equipment vendors
Intellectual property companies
Research organization, etc.

5. 3GPP 3GPP Partner organizations Website: www.3gpp.org/
3GPP – 3rd Generation Partnership Program
Group of regionally based partner organizations
Development of standards that are evolution of GSM
Standards are structured as releases:
Phase 1 and 2, ( ) – covers only GSM (2G)
Release 96-98, ( ) – cover GSM/GPRS/EDGE (2.5G)
Release 99, (1999) – covers GSM/GPRS/EDGE and UMTS (3G)
Release 4-7 ( ) – GSM/GPRS/EDGE/UMTS/HSPA (3G)
Release 8-12 ( ) – GSM/GPRS/EDGE/UMTS/LTE/ALTE (4G)
There are four technical groups in 3GPP
GERAN: GSM and EDGE radio access network (2G RAN)
RAN: UTRAN and E-UTRAN (3G/4G RAN)
SA: Service and system aspects
CT: Core network and terminals
3GPP Partner organizations
Organization
Region
Association of Radio Industries and Businesses (ARIB)
Japan
Alliance for Telecommunications Industry Solutions (ATIS)
USA
European Telecommunications Industry Association (ETSI)
Europe
China Communications Standards Association (CCSA)
China
Telecommunications Technology Association (TTA)
Korea
Telecommunication Technology Committee (TTC)
Website:

6. Cellular generations Cellular telephony started in early 80s
Over three decades – four generations of technology
First generation: Analog voice only
Second generation: Digital voice
Third generation: Digital voice and data
Fourth generation: Wireless broadband
Multiple generations of mobile phones 1G 2G 3G 4G
Note: Just like phones, the infrastructure evolves as well

7. Example: 1G systems used in Europe before standardization of GSM
1G cellular
1G cellular – analog voice
Introduced in 1980s
Deployed in 450MHz and 850MHz bands
Not standardized: many different technologies
Not very efficient
Relatively expensive (no economy of scale)
Quickly ran out of capacity
In the US, 1G (AMPS) terminated in 2008
Example of 1G phone – Motorola DynaTAC
(2lbs weight, $9000 cost)
Example: 1G systems used in Europe before standardization of GSM

8. In 2G, mobiles are still primarily phones
2G cellular
2G cellular – digital voice
Introduced in mid 1990
Several competing technologies
Global System for Mobile communication (GSM)
D-AMPS (IS-54 and IS-136)
IS-95 CDMA
iDEN (Motorola proprietary)
Personal Digital Cellular (PDC)
Optimized for voice
Except GSM – mostly proprietary (single vendor)
Except for GSM – all obsolete
GSM – dominant technology in developing world today
In 2G, mobiles are still primarily phones

9. In 3G mobiles become personal communication devices (voice and data)
3G cellular
Need – to provide data services
Two types of technologies
3GPP
UMTS (voice and low speed data)
HSPA (high speed data)
3GPP2
Cdma2000 (voice and low speed data)
EvDO (high speed data_
Designed for both voice and data
Two parallel networks in one
In 3G mobiles become personal communication devices (voice and data)

10. 4G cellular and beyond 4G: Long Term Evolution (LTE)
Standardized in 2008
Deployment started in 2010
Optimized for mobile data
Voice delivered through VoIP
Fastest adoption in mobile history
Fast adoption fueled by demand for wireless broadband
Release
Standardized
Commercial
Major features
3GPP R8 (LTE)
2008
2010
Multi antenna support
Channel dependent scheduling
Bandwidth flexibility
ICIC (Intercell Interference Coordination)
Hybrid ARQ
FDD + TDD support
3GPP R9 (LTE)
2009
Dual layer beam forming
Network based UE positioning
MBSFN (Multicast/Broadcast Single Frequency Network)
3GPP R10 (LTE)
LTE Advanced
Multi antenna extension
Relaying
Carrier aggregation
Heterogeneous networks (HetNet’s)

11. Evolutionary paths for cellular technologies
Within next decade – global convergence of cellular standards
Convergence – both radio access and core network
LTE – wireless technology with the fastest adoption rate
Technology convergence
Levels playing field
Shift competition towards consumer-end features
Allows entrance of large scale re-sellers
Technology migration paths

12. Cellular generation trend
4G deployment – global rapid shift towards mobile broadband
Facilitated by
Availability of smartphones
Rapid expansion of 3G/4G coverage
Operator subsidies for smart phone devices
By 2020 it is projected that 70% of Internet connectivity will be through 3G/4G
4G provides more economical data connectivity than 3G
2Q 2015 – about 700M LTE subs
Year
# LTE networks
# Countries with LTE
2010 17 11
2011 47 23
2012
144 62
2013
256 97
2014
335
118
Global deployment of 4G

13. Review questions What is 3GPP?
What is the most successful 2G technology?
What generation does UMTS belong to?
When was the LTE standardized?
When were first LTE deployments?
What is the most important market driver behind LTE deployments?

14. Part 4
FUNDAMENTAL CONCEPTS

15. Elements of cellular system architecture
Three major blocks
Mobile terminal (user equipment - UE)
Radio Access Network (RAN)
Core Network (CN)
Standardization focuses on interfaces between blocks
The most important interface – “air interface”
Cellular networks interface with both PSTN and Internet
Generic diagram of a cellular network

16. User equipment (UE) UE may be Complex and versatile equipment
Modern UE separates: Mobile Equipment (ME) from User identity
Mobile Equipment (ME) - hardware providing the adjustment of user data to the air interface
Subscriber Module (SIM card). Detaches the user identity from a given communication hardware
UE may be
Multimode (support for multiple technologies)
Multiband (support for different frequency bands)
Example of SIM and ME separation in 3G
Some contemporary phones

17. Radio Access Network (RAN)
Radio Access Network – radio frequency part of the cellular network
Provides means of connecting UE to CN
Types of RAN
GRAN: GSM Radio Access Network
GERAN: GSM/EDGE Radio Access Network
UTRAN: UMTS Radio Access Network
E-UTRAN: Evolved UTRAN
Typically RAN consists of
Base stations (host of transceivers)
Base station controllers (except in LTE)
Example of 2G/3G RANs
Multiple RANs may be connected to the same core network.

18. Core network (CN)
Telecommunication network similar to non-cellular networks
Types of traffic (by switching)
Circuit switching (used primarily for voice)
Packet data
Traffic types (by plane)
User traffic (voice or data)
Signaling (traffic between the network nodes)
Interfaces with external networks
PSTN (Public Switched Telephone Network)
PDN (Packet Data Network – usually Internet)
Core network

19. Network layout – 2G 2G Networks – dedicated to voice service
Base Station Subsystem – BSS (RAN)
Mobile Station Subsystem - MSS
Network Switching Subsystem – NSS (core)
BTS – Base Station TRX
TRX – Transceiver
BSC – Base station controller
TRAU – Transcoding and Rate Adaptation Unit
MSC – Mobile Switching Center
BSS – Base Station Subsystem
NSS – Network Subsystem
VLR – Visitor Location Registry
HLR – Home Location registry
Example of 2G network
Note: voice only and circuit switched network

20. Circuit / packet switching
Traditional telephone networks are circuit switched
Dial-up type connections
A single user occupies a channel for the entire transmission
Requires time-oriented billing
Data networks use packet switching
Data are sent in small units called packets
Use of network resources is ‘on demand’
Billing is based on usage and Quality of Service
Circuit switching - efficient for delivery of voice. Not efficient for delivery of data.
Packet switching – efficient way for data communication

21. Types of packet switching
Datagram packet switching
Every packet travels independently
Implemented within IP based networks
Transport layer has to assure the proper order of the packets
Virtual path packet switching
Virtual path (sequence of network nodes) is established through the network
Implemented within ATM networks
Virtual path switching
Datagram switching
Note: Modern packet data networks are using datagram switching (TCP/IP) protocol stack

22. Example 1: Network layout – 2.5G
Two parts
CS part
Packed data
Common databases
Billing
Location management
Quite complicated
Many different nodes
Many interfaces
GSM based air interface
FDMA/TDMA with frequency hopping
2.5G = GSM/EDGE

23. Example 2: Network layout – 3G
Same basic architecture as 2.5G
CS part
PD part
Significant change – air interface
Standardized interfaces
Uu (Air interface)
Iu (UTRAN to CN)
Iub (Node B to RNC)
Iur (between RNCs)
Block diagram of 3G network
RNC – Radio Network Controller
Node B – base station
MSC – Mobile Switching Center
SGSN/GGSN – packet data service nodes (routers)

24. Duplexing Cellular communications is full duplex
Communication from MS to BS -> uplink
Communications from BS to MS -> downlink
Two ways for full duplex
Frequency Division Duplexing (FDD)
Time Division Duplexing (TDD)
Frequency Division Duplexing (FDD)
More common
Uses paired spectrum allocation
One part (usually lower in frequency) – uplink
Second part (usually higher in frequency) – downlink
Lower frequencies used for UL due to slightly better propagation
Note: frequency separation between UL and DL is referred to as the duplexing separation / duplexing space

25. Multiple access
Multiple access – specifies method of sharing air interface between different users
Air interface – bottle neck of the cellular communications
Efficient sharing scheme – very important
Multiple access methods used in cellular systems
Frequency Division Multiple Access (FDMA)
Time Division Multiple Access (TDMA)
Code Division Multiple Access (CDMA)
Orthogonal FDMA (OFDMA)
Single Carrier OFDMA (SC-OFDMA)
Multiple access scheme – large factor in performance and capacity of a cellular system
May be implemented with either FDD or TDD
Air-interface: radio interface between mobiles and cellular base stations

26. Frequency Division Multiple Access (FDMA)
Users separated in frequency domain
Each cellular link is allocated a pair of frequencies
Interference avoided – no two links that are geographically close use the same frequency pair
Has to be thoroughly planned – frequency planning
Used in GSM (2G) as a primary access scheme
Illustration of FDMA

27. Time Division Multiple Access (TDMA)
Users share the same frequency pair
Time is divided into time slots
Users get allocated different time slots
Time slots different for UL and DL
Avoid use of RF duplexer
There may be N different users on the same frequency
Landline T1: 24 users
GSM: 8 in full rate or 16 in half rate
Interference avoidance through frequency planning and synchronization
Illustration of TDMA

28. Code Division Multiple Access (CDMA)
Users share the same frequency pair
Users transmit at the same time
Signals are encoded using orthogonal sequences – basis for their separation at the receiver
Interference avoidance through power and code management
Implement frequency reuse pattern of N = 1
Utilized in all technologies of 3rd generation
Illustration of CDMA

29. Orthogonal FDMA
Users managed in three domains: time, frequency, code domain
Frequency band segmented into multiple tones
Time segmented into time slots
Users allocated portion of tones for some time slots
Allocation is dynamic
Used in LTE, WiMAX and WiFi
Interference avoided through effective scheduling schemes
Efficient but complex scheme

30. Review questions What are three major parts of a cellular network?
What does RAN stand for?
What is the difference between GERAN and UTRAN?
Is it possible for GERAN and UTRAN to share the same CN?
What is the difference between circuit switching and packet switching?
What are two different forms of packet switching?
Why is circuit switching inefficient for data communication?
What is the difference between TDD and FDD?
What is the duplexing space in TDD?
Does GSM use FDMA, TDMA or both?
What is the multiple access scheme used in UMTS and HSPA?

31. Part 3
LTE/SAE overview

32. Mobile broadband (3GPP)
Release
Standardized
Commercial
Major features
3GPP R99
1999
2000
Bearer services
64 kbit/s CS
384 kbit/s PS
Location services
Call services: compatible with GSM
3GPP R5
2002
2006
IP Multimedia Subsystem (IMS)
IPv6, IP transport in UTRAN
Improvements in GERAN
HSDPA
3GPP R6
2004
2007
Multimedia broadcast and multicast
Improvements in IMS
HSUPA
Fractional DPCH
3GPP R7
2008
Enhanced L2
64 QAM , MIMO
VoIP over HSPA
CPC - continuous packet connectivity
FRLC - Flexible RLC
3GPP R8
2010
DC-HSPA+ (Dual Cell HSPA+)
HSUPA 16QAM
3GPP R8 (LTE)
New air interface (OFDM/SC-FDMA)
New core network
3G continues to evolve
Standardized through 3GPP
3G gracefully evolves into 4G – starting from R7 and R8
Date rates
R99: 0.4Mbps UL, 0.4Mbps DL
R5: 0.4Mbps UL, 14Mbps DL
R6: 5.7Mbps UL, 14Mbps DL
R7: 11Mbps UL, 28Mbps DL
R8: 50Mbps UL on LTE, 160 Mbps DL on LTE, 42Mbps DL on HSPA
Two branches of the standards
HSPA : Gradual performance improvements at lower incremental costs
LTE: revolutionary changes with significant performance improvements (higher cost, first step towards IMT advanced)

33. LTE Releases LTE – has an “evolution path” of its own
Standardized
Commercial
Major features
3GPP R8 (LTE)
2008
2010
Multi antenna support
Channel dependent scheduling
Bandwidth flexibility
ICIC (Intercell Interference Coordination)
Hybrid ARQ
FDD + TDD support
3GPP R9 (LTE)
2009
Dual layer beam forming
Network based UE positioning
MBSFN (Multicast/Broadcast Single Frequency Network)
3GPP R10 (LTE)
LTE Advanced
Multi antenna extension
Relaying
Carrier aggregation
Heterogeneous networks (HetNet’s)
LTE – has an “evolution path” of its own
Evolution is towards IMT-Advanced (LTE advanced)
LTE advanced – spectral efficiency 30bps/Hz (DL), 15bps/Hz (UL)
Note: This presentation focuses on R8-R10 features

34. DL target relative to base line UL target relative to baseline
LTE requirements
Outlined in 3GPP TR
Seven different areas
Capabilities
System performance
Deployment related aspects
Architecture and migration
Radio resource management
Complexity, and
General aspects
DL data rate > 100 Mbps in 20 MHz
UL data rate > 50 Mbps in 20MHz
Rate scales linearly with spectrum
Latency user plane: 5ms (transmission of small packet from UE to edge of RAN)
Latency control plane: transmission time from camped state – 100ms, transmission time from dormant state 50 ms
Support for 200 mobiles in 5MHz, 400 mobiles in more than 5MHz
System performance
Baseline is HSPA Rel. 6
Throughput specified at 5% and 50%
Maximum performance for low mobility users (0-15km/h)
High performance up to 120 km/h
Maximum supported speed 500km/h
Cell range up to 100km
Spectral efficiency for broadcast 1 b/s/Hz
Throughput requirements relative to baseline
Performance measure
DL target relative to base line
UL target relative to baseline
Average throughput per MHz
3-4 times
2-3 times
Cell edge user throughput per MHz
Spectrum efficiency (bit/sec/Hz)

35. Non-real time services (ms) Real time services (ms)
LTE requirements (2)
Deployment related aspects
LTE may be deployed as standalone or together with WCDMA/HSPA and/or GSM/GPRS
Full mobility between different RANs
Handover interruption time targets specified
Spectrum flexibility
Both paired and unpaired bands
IMT 2000 bands (co-existence with WCDMA and GSM)
Channel bandwidth from MHz
Handover interruption time
Non-real time services (ms)
Real time services (ms)
LTE to WCDMA
500
300
LTE to GSM
LTE duplexing options

36. LTE requirements (3) Architecture and migration
Single RAN architecture
RAN is fully packet based with support for real time conversational class
RAN architecture should minimize “single points” of failure
RAN should simplify and reduce number of interfaces
Radio Network Layer and Transport Network Layer interaction should not be precluded in interest of performance
QoS support should be provided for various types of traffic
Radio resource management
Support for enhanced end to end QoS
Support for load sharing between different radio access technologies (RATs)
Complexity
LTE should be less complex than WCDMA/HSPA

37. SAE design targets SAE – Service Architecture Evolution
SAE = core network
Requirements placed into seven categories
High level and operational aspects
Basic capabilities
Multi-access and seamless mobility
Man-machine interface aspects
Performance requirements for Evolved 3GPP system
Security and privacy
Charging aspects
SAE requirements mainly non access related (highlighted ones have impact on RAN)

38. Basic principles – Air interface
Downlink OFDM
OFDM = Orthogonal Frequency Division Multiplexing
OFDM = Parallel transmission on multiple carriers
Advantages of OFDM
Avoidance of intra-cell interference
Robust with respect to multi-path propagation and channel dispersion
Disadvantage of OFDM
High PAPR and lower power amplifier efficiency
Uplink DFTS-OFDM (SC-FDMA)
DFTS = DFT spread OFDM
SC-FDMA = Single carrier FDMA
Advantages (all critical for UL)
Signal has single carrier properties
Low PAPR
Similar hardware as OFDM
Reduced PA cost
Efficient power consumption
Disadvantage
Channel equalizer needed (not critical from UL)
UL modulation
DL modulation

39. Basic principles – Air interface
Shared channel transmission
Only PS support
No CS services
Fast channel dependent scheduling
Adaptation in time
Adaptation in frequency
Adaptation in code
Hybrid ARQ with soft combining
Chain combining
Incremental redundancy
One shared channel simplifies the overall signaling
Scheduler takes the advantage of time-frequency variations of the channel
ARQ reduces required Eb/No

40. Basic principles – air interface
MIMO support
MIMO = Multiple Input Multiple Output
Use of multiple TX / RX antennas
Three ways of utilizing MIMO
RX diversity/TX diversity
Beam forming
Spatial multiplexing (MIMO with space time coding)
MIMO transmission in Rayleigh fading environment increases theoretical capacity by a factor equal to number of independent TX RX paths
As a minimum LTE mobiles have two antennas (possibly four)
Outline of spatial multiplexing idea
Note: Rayleigh fading de-correlates the paths and provides multiple uncorrelated channels

41. Basic principles – air interface
ICIC – Inter-cell interference coordination
LTE affected by inter-cell interference (more than HSDPA)
In LTE interference avoidance becomes scheduling problem
By managing resources across multiple cells inter-cell interference may be reduced
Standard supports exchange of interference indicators between the cells
One possible implementation of ICIC. Cell edge implements N=3. Cell interior implements N=1.

42. SAE-Architecture LTE Network layout
SAE – flat architecture
Core network,
E-UTRAN
RAN consist of single element type: eNode B
Single element simplifies RAN
No single point of failure
Core network provides two planes
User plane (through SGSN)
Control plane (through MME)
Interfaces
S1-UP (eNode B to SGSN)
S1-CP (eNode B to MME)
X2 between two eNode Bs (required for handover)
Uu (UE to eNode B)
LTE Network layout
UE – user equipment (i.e. mobile)
eNode B – base station
SGSN – Support GPRS Serving Node
GGSN – Gateway GPRS Serving Node
MME – Mobility Management Entity
PCRF - Policy and Charging Rules function
SAE = System Architecture Evolution

43. Review questions What are the noted in the LTE RAN?
How is voice service provisioned in LTE?
What is PC (Packet Core)?
What multiple access scheme is used on LTE downlink?
What does MIMO stand for?
What radio resources are managed by the LTE scheduler?
What is radio channel adaptation?
What are components of SAE?