2. Jargons
• Mobile networks use many jargon and
abbreviations
– LTE, EPS, Node B, eNodeB
– Nested acronyms are common
– GERAN = GPRS Evolution Radio Access Network
– LTE is often referred to as Evolved Packet System (EPS)
in technical situations
• Learn the jargon and acronyms gradually
– There is an associated glossary and cheat-sheet
– I do not remember many
2
CS590 (Peng)
3. Outline
• Evolution of mobile networks
• Network architecture
• Network operations and protocol stack
3
CS590 (Peng)
5. Ubiquitous Mobile Network Services
• Global Mobile Data Traffic
– 7.2 exabytes/month in 2016 (63% growth)
– 18 fold growth in the past five years
– 7 fold growth by 2021 (49 exabytes/month)
5
5
Source: Cisco Visual Networking Index, 2017: Global Mobile Data Traffic Forecast Update, 2016–
2021 White Paper
CS590 (Peng)
6. Ubiquitous Mobile Network Services
• Smartphones: primary internet access points
– By 2021, 98% traffic and 75% connections from
“smart” devices
– 4G: 75% traffic and 53% connections
– 5G: 1.5% traffic and 0.2% connections
CS590 (Peng) 6
7. Empowered by Mobile Networks
Internet
Network
Infrastructure
Mobile
Client
7
… ...
• the only large-scale, wide-area wireless network
system in par with the Internet
CS590 (Peng)
8. Empowered by Mobile Networks
8
Network
Infrastructure
Mobile
Client
… ...
Wireless
(radio access
technology)
CS590 (Peng)
9. Mobile Network Evolution
CS590 (Peng) 9
1G 2G 3G 4G 5G
Mid 1980s 1990s 2000s 2010s 2020s
analog
voice
Digital voice
+ Simple data
Mobile
broadband
Mobile Internet
More & faster
3G
WCDMA/HSPA+
CDMA2000/EVDO
TD-SCDMA
1G
AMPS, NMT
TACS
2G
GSM/GPRS/
EDGE
cdmaOne
4G
LTE
LTE-A
10. Standards Body: 3GPP
• An international standards body
• Evolves and standardizes GSM, UMTS, LTE
among others
The 3rd Generation Partnership Project (3GPP) unites
[Six] telecommunications standard development
organizations (ARIB, ATIS, CCSA, ETSI, TTA, TTC), known as
“Organizational Partners” and provides their members
with a stable environment to produce the highly
successful Reports and Specifications that define 3GPP
technologies
• We will primarily discuss 3GPP standards
CS590 (Peng) 10
12. What is LTE?
• LTE stands for “Long Term Evolution”
• Fourth-generation (4G) cellular technology
from 3GPP
• Deployed worldwide
• 4G LTE: First global standard
– Increased speed
– IP-based network (All circuits are gone/fried!)
– New air interface: OFDMA (Orthogonal Frequency-
Division Multiple Access), MIMO (multiple antennas)
• Also includes duplexing, timing, carrier spacing, coding...
– New service paradigm (e.g., VoLTE)
CS590 (Peng) 12
13. What is LTE?
• LTE is always evolving and 3GPP often has new
“releases”
– First release: Rel-8
– Current: Rel-11, Rel-12
– Toward LTE-Advanced (4.5G)
CS590 (Peng) 13
15. Inter-Generation Technologies
• CS networks need to be able to connect with PS
networks and other distinct cellular networks
– The internet is a good example of PS network
• GPRS (General packet radio service)
– 2.5G packet switched technology
• EDGE (Enhanced Data Rates for GSM Evolution)
– 2.75G packet switched technology
• HSPA (High Speed Packet Access)
– 3.5/3.75 packet switched data technology
– There were a few quick iterations on this technology,
thus “variants”
CS590 (Peng) 16
16. 2G Network Architecture (GSM)
17
UE
BTS
BSC
MSC
Base Station
Subsystem
Network
Subsystem
Operations and Support
Subsystem
HLR/AuC
17
CS590 (Peng)
17. 2G Based on Circuit Switching (CS)
End-end resources
reserved for “call”
• link bandwidth, switch
capacity
• dedicated resources: no
sharing
• circuit-like (guaranteed)
performance
• call setup required CS590 (Peng) 18
18. CS Signaling
• used to setup, maintain teardown VC
• used in 2G, as well as in 3G
• not used in today’s Internet
CS590 (Peng) 19
application
transport
network
data link
physical
application
transport
network
data link
physical
1. Initiate call 2. incoming call
3. Accept call
4. Call connected
5. Data flow begins 6. Receive data
19. 4G Network Architecture (LTE)
Signaling path
Data path
MME 4G Core Network
4G BS
Internet
Phone
4G PS Gateways
MME: Mobility Management Entity
BS: Base Station (4G: eNodeB)
4G Packet-Switched
CS590 (Peng) 20
20. Packet Switching (PS)
• Sequence of A & B packets does not have fixed
pattern, bandwidth shared on demand statistical
multiplexing
• Store-and-forward at intermediate routers
• Used by the Internet CS590 (Peng) 21
A
B
C
D E
statistical multiplexing
queue of packets
waiting for output link
21. PS Signaling
• no call setup at network layer
• routers: no state about end-to-end connections
– no network-level concept of “connection”
• packets forwarded using destination host address
– packets btw same source-dest pair may take different paths
CS590 (Peng) 22
application
transport
network
data link
physical
application
transport
network
data link
physical
1. Send data 2. Receive data
23. So far, Our Focus
• We mainly focus on current 3G/4G systems,
particularly 4G LTE network
CS590 (Peng) 24
Network
Infrastructure
Mobile
Client
… ...
Wireless
(radio access
technology)
24. Outline
Evolution of mobile networks
Network architecture
• Network operations and protocol stack
25
CS590 (Peng)
25. Operations
Two main planes in operation in parallel:
• Data plane (also called User plane): content
delivery
• Control plane: signaling functions
There is an additional plane that works with the
above two planes:
• Management plane: configurations,
monitoring
CS590 (Peng) 26
26. Illustration of Data and Control Planes
CS590 (Peng) 27
Network
Infrastructure
Data-plane
Control-
Plane
IP
Application
Transport
Data-plane
Control-
Plane
IP
27. Illustration of Data and Control Planes
CS590 (Peng) 28
PHY
MAC
PDCP
IP
L1
L2
L3
4G-PHY
4G-MAC
4G-RLC
IP
PDCP
Data
Plane
3G 4G LTE
RLC
Control
Plane
Data
Plane
Radio Resource Contol
Mobility Management
Connectivity Mangement
Connectivity
Management
Mobility
Management
Radio
Resource
Control
Session
Management
(SM)
EPS Session
Management
(ESM)
Mobility
Management
(GMM)
Radio Resource Control
(3G-RRC)
4G LTE
3G
Call Control
(CM/CC)
Mobility
Management
(MM)
Radio
Resource
Control
(4G-RRC)
Mobility
Management
(EMM)
PS Domain
PS Domain
CS Domain
28
28
EPS: Evolved Packet System
PDCP: Packet Data Convergence Protocol
RLC: Radio Link Control
MAC: Medium Access Control
28. Data-Plane Protocols: IP + lower layers
• Packet Data Convergence Protocol (PDCP) – header
compression, radio encryption
• Radio Link Control (RLC) – Readies packets to be transferred
over the air interface
• Medium Access Control (MAC) – Multiplexing, QoS
CS590 (Peng) 29
PDCP
RLC
@eNB (IP)
PDCP
RLC
@UE (IP)
MAC
PHY
MAC
PHY
29. 30
Control-Plane Protocols
Internet
Data-plane
Control-plane
P1: Radio conn. setup
P2: Location
update
P3: Conn.
context
(QoS)
Radio Resource Control (RRC)
Mobility Management (MM)
Connectivity Management
• Control utilities: mobile network specific
– Different from Internet counterparts
30. Control-Plane Protocols in 4G/3G
• Variants for same/similar control functions
– Hybrid 4G/3G systems
– Domains separated for voice (CS) and data (PS)
CS590 (Peng) 31
PHY
MAC
PDCP
IP
L1
L2
L3
4G-PHY
4G-MAC
4G-RLC
IP
PDCP
Data
Plane
3G 4G LTE
RLC
Control
Plane
Data
Plane
Radio Resource Contol
Mobility Management
Connectivity Mangement
Connectivity
Management
Mobility
Management
Radio
Resource
Control
Session
Management
(SM)
EPS Session
Management
(ESM)
Mobility
Management
(GMM)
Radio Resource Control
(3G-RRC)
4G LTE
3G
Call Control
(CM/CC)
Mobility
Management
(MM)
Radio
Resource
Control
(4G-RRC)
Mobility
Management
(EMM)
PS Domain
PS Domain
CS Domain
31. Distributed Operations: Device, base
station, core networks
3G CS Gateway
MME
3G PS Gateway
3G 4G
Core
Network
User
Device
PS CS
Base
Station 3G-RRC
MM
MM
CM
CM
4G-RRC
MM
CM
CS590 (Peng)
32
32. Put Them Together
• Setting up data service in 4G
CS590 (Peng) 33
Internet
Data-plane
Control-plane
33. Data and Control Planes in LTE
34
• eNodeB, S-GW
and P-GW are
involved in
session setup,
handoff, routing
User
Equipment
(UE)
Gateway
(S-GW)
Mobility
Management
Entity (MME)
Network
Gateway
(P-GW)
Home
Subscriber
Server (HSS)
Station
(eNodeB)
Base
Station
Serving Packet Data
Control Plane
Data Plane
34. Setting Up Data Service in 4G
35
User
Equipment
4G BS MME
RRC Connection Request
RRC Connection Setup
RRC Connection Complete
4G-
RRC
4G-
RRC
4G-
MM
Attach Request
Authentication Request
Authentication Response
Attach Accept
Attach Complete
4G-
MM
Public Data Network Connectivity Request
Activate Bearer Context Request (192.168.0.199)
Activate Bearer Context Accept
4G-
CM
4G-
CM
PDN: Public Data Network EPS: Evolved Packet System
(1) Setup radio connection
(2) Registration (attach)
(3) Authentication
(4) Setup Connectivity Context
(e.g., IP, routing path, QoS)
Others
(HSS, GWs)
HSS
P-Gw
35. Setting Up Data Service in 4G
36
User
Equipment
4G BS MME
4G-
RRC
4G-
RRC
4G-
MM
4G-
MM
4G-
CM
4G-
CM
(1) Setup radio
connection
(2) Registration (attach)
(3) Authentication
(4) Setup Connectivity Context
(e.g., IP, routing path, QoS)
Others
(HSS, GWs)
HSS
P-Gw
(5) data-plane delivery
Control-Plane Functions
36. Summary and Discussion
• Primer on mobile network: architecture,
protocols, operations
– And its evolution
– And its complexity
• Difference from wired Internet and WiFi
– What?
– Why?
CS590 (Peng) 37
37. After-class Reading (Optional)
• Learn more about control plane protocols and
their interactions: SIGCOMM’14
• Learn more about radio connection setup:
check RRC papers
• LTE tutorial and reference:
https://www.tutorialspoint.com/lte/
CS590 (Peng) 38
38. Action Items
• Work on your course project early
– Topic and team
• Check the reference and reading list
– Updates shortly
• Next Chapter: 5G apps
CS590 (Peng) 39
Editor's Notes
Lecture 1:
(1)
Today, mobile internet anywhere, anytime.
(2) Today, Almost everyone can use mobile Internet anytime, anywhere.
%mobile Internet has become an important part of our everyday life.
Soruce: https://www.cisco.com/c/en/us/solutions/collateral/service-provider/visual-networking-index-vni/mobile-white-paper-c11-520862.html
(1) We still witness increasing growth.
Forecast: Mobile Network Through 2021
49 exabytes/month (6.8x growth)
4G: 75% traffic and 53% connections
5G: 1.5% traffic and 0.2% connections
98% traffic &75% connections from “smart” devices
he Mobile Network Through 2021
Mobile data traffic will reach the following milestones within the next 5 years:
● Monthly global mobile data traffic will be 49 exabytes by 2021, and annual traffic will exceed half a zettabyte.
● Mobile will represent 20 percent of total IP traffic by 2021.
● The number of mobile-connected devices per capita will reach 1.5 by 2021.
● The average global mobile connection speed will surpass 20 Mbps by 2021.
● The total number of smartphones (including phablets) will be over 50 percent of global devices and connections by 2021.
● Smartphones will surpass four-fifths of mobile data traffic (86 percent) by 2021.
● 4G connections will have the highest share (53 percent) of total mobile connections by 2021.
● 4G traffic will be more than three-quarters of the total mobile traffic by 2021.
● More traffic was offloaded from cellular networks (on to Wi-Fi) than remained on cellular networks in 2016.
● Over three-fourths (78 percent) of the world’s mobile data traffic will be video by 2021.
To connect these smartphones and the Internet, the key enabler is the underlying mobile networked system.
Mobile clients first get wireless access to the base stations and then traverse several gateways in the rest mobile network infrastructure and finally reach the external Internet.
(3) So far and also in the coming years, this is still the only large-scale, wide-area wireless network system, which complements the wired Internet.
To connect these smartphones and the Internet, the key enabler is the underlying mobile networked system.
Mobile clients first get wireless access to the base stations and then traverse several gateways in the rest mobile network infrastructure and finally reach the external Internet.
(3) So far and also in the coming years, this is still the only large-scale, wide-area wireless network system, which complements the wired Internet.
All these are empowered by the evoluation of mobile networks.
Today, the world is advancing to 4G LTE and even LTE advanced.
At this time point, almost everyone knows that 3G/4G mobile networks are everywhere.
This fact can be easily supported by many numbers.
For example, 3G/4G have been deployed in 203 countries; serving 6.8 billions user.
By 2014 (this year), it will go beyond our global population.
Last year, more than half a billion smartphones and tablets are shipped,
The market is $1 trillion by 2016.
And so on…
=========================================================
Mobile network is the largest scale wireless infrastructure.
It covers the whole planet and serves billions of users.
It provides mobile users with data service and carrier-grade quality voice service
There are other standards, like 3GPP2, 5GPP
CAT 3, CAT 4, CAT 6 (different radio technology), different speed
All implementations must meet baseline requirements
Increased speed
IP-based network (All circuits are gone/fried!)
New air interface: OFDMA (Orthogonal Frequency-Division Multiple Access), MIMO (multiple antennas)
Also includes duplexing, timing, carrier spacing, coding...
CAT 3, CAT 4, CAT 6 (different radio technology), different speed
Enhancement over time (CAT3, CAT 4, CAT 6),
All implementations must meet baseline requirements
Increased speed
IP-based network (All circuits are gone/fried!)
New air interface: OFDMA (Orthogonal Frequency-Division Multiple Access), MIMO (multiple antennas)
Also includes duplexing, timing, carrier spacing, coding...
Let us look at the mobile network architecture to see how these services are made possible.
Here it is a 4G LTE network architecture which only supports packet-switched service.
It consists of two parts:
First, base stations to offer radio access
Second, core network which consists of MME (Mobility Management Entity) and 4G PS gateways .
The MME is used to manage user mobility, e.g., location update.
The 4G PS Gateways route packets between Internet and 4G Base stations
Now we take a look at 3G network architecture.
Similar to 4G LTE, it has Base station and core networks.
The major difference is that 3G supports both Circuit-Switched and Packet-Switched services.
3G CS Gateways are used to connect to 3G base stations and telephony networks.
3G PS Gateways plays role similar to 4G PS Gateway.
The main difference is that 3G PS Gateways are responsible for control-plane and data-plane functions at same.
In 4G LTE, the control-plane functions are moved to MME.
Wireless technology, main evolution across different generations and releases are in PHY layer
It means that the network side implements complex functions.
(2) To support data delivery in the data-plane, it has to support rich control-plane functions like radio resource control, mobility support, connectivity management, QoS control etc.
(3) They are much more complex than the control in the Internet.
(1 ) Layered protocol stack
(2) Variants
(3) Complicated (rich set of control protocols)
We use one most common operation to explain how they work together.
RRC study:
A Close Examination of Performance and Power Characteristics of 4G LTE Networks, by Junxian Huang, Feng Qian, Alexandre Gerber, Z. Morley Mao, Subhabrata Sen, and Oliver Spatscheck, ACM Mobisys 2012.
MN2: [qian10-rrc3g-imc] Characterizing Radio Resource Allocation for 3G Networks, by Feng Qian, Zhaoguang Wang, Alex Gerber, Z. Morley Mao, Subhabrata Sen, and Oliver Spatscheck, ACM IMC 2010.
MN2: [qian11-aro-mobisys] Profiling Resource Usage for Mobile Applications: a Cross-layer Approach by Feng Qian, Zhaoguang Wang, Alex Gerber, Z. Morley Mao, Subhabrata Sen, and Oliver Spatscheck, ACM Mobisys 2011.
MN2:[balasubramanian09-rrctail-imc] Energy Consumption in Mobile Phones: A Measurement Study and Implications for Network Applications, by Niranjan Balasubramanian Aruna Balasubramanian Arun Venkataramani, ACM IMC 2009. (It focuses on energy model. RRC tail is introduced).
*MN2: [athivarapu12-radiojockey-mobicom] RadioJockey: Mining Program Execution to Optimize Cellular Radio Usage, by Pavan Kumar Athivarapu, Ranjita Bhagwan, Saikat Guha, Vishnu Navda, Ramachandran Ramjee, Dushyant Arora, Venkat Padmanabhan, and George Varghese, ACM MobiCom 2012.
