Wi-Fi Integration to the 4G Mobile Network E-Book

Andre Perez

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 281

Veröffentlichungsjahr: 2018

Beschreibung

The adoption of smartphones has had as a corollary the use of services that require streaming, such as video streaming, which is a constraint for the 4G mobile network. The integration of the network of Wi-Fi hotspots deployed by the operators adds capacity to the 4G mobile network. The use of Wi-Fi technology in carrier networks is the result of developments coordinated by the IEEE, WFA and WBA standardization bodies. For its part, the 3GPP standardization body has been working to integrate Wi-Fi technology into the 4G mobile network. The first part of this book presents the characteristics of the Wi-Fi radio interface. The different IEEE 802.11b / g / n / ac physical layers characterize the implementation in the 2.4 GHz ISM frequency bands and U- NII at 5 GHz. The MAC layer defines a number of media access procedures such as scanning, associating, or transferring data. The second part of this book deals with the architecture of the 4G network based on the Wi-Fi interface. This architecture defines several models corresponding, on the one hand, to Wi-Fi access controlled or not, On the other hand, to a handover controlled by the network or by the mobile. The integration of Wi-Fi technology resulted in a redefinition of attachment and session set-up procedures. Smartphones have the ability to activate simultaneously the two radio interfaces, LTE and Wi-Fi, which allows to direct certain services to one and / or the other of the interfaces. The ANDSF and HotSpot 2.0 functions provide the mobile with rules for network selection and traffic control to determine which traffic is to be routed to what type of interface.

Leseprobe

Table of Contents

Cover

Title

Copyright

List of Abbreviations

Introduction

I.1. 4G mobile network

I.2. Wi-Fi network

I.3. Wi-Fi integration into the 4G mobile network

I.4. Wi-Fi and LTE access aggregation

1 Architecture Based on Wi-Fi Access

1.1. Functional architecture

1.2. Tunnel establishment

1.3. DIAMETER protocol

2 MAC Layer

2.1. Frame structure

2.2. Procedures

2.3. Security

2.4. Quality of service

3 802.11a/g Interfaces

3.1. 802.11a interface

3.2. 802.11g interface

4 802.11n Interface

4.1. MAC layer evolution

4.2. PLCP sub-layer

4.3. PMD sub-layer

5 802.11ac Interface

5.1. MAC layer

5.2. PLCP sub-layer

5.3. PMD sub-layer

6 Mutual Authentication

6.1. 802.1x mechanism

6.2. Key management

6.3. Application to the 4G mobile network

7 SWu Tunnel Establishment

7.1. IPSec mechanism

7.2. Application to the 4G mobile network

8 S2a/S2b Tunnel Establishment

8.1. PMIPv6 mechanism

8.2. GTPv2 mechanism

8.3. MIPv4 FA mechanism

9 S2c Tunnel Establishment

9.1. MIPv6 mechanism

9.2. DSMIPv6 mechanism

9.3. Application to the 4G mobile network

10 Network Discovery and Selection

10.1. Mechanisms defined by 3GPP organization

10.2. Mechanisms defined by IEEE and WFA organizations

11 Carrier Aggregation

11.1. Functional architecture

11.2. Protocol architecture

11.3. Procedures

11.4. PDCP

12 MPTCP Aggregation

12.1. Functional architecture

12.2. TCP

12.3. MPTCP

Bibliography

Index

End User License Agreement

List of Tables

Chapter 1 Architecture Based on Wi-Fi Access

Table 1.1. DIAMETER messages on the SWx interface

Table 1.2. DIAMETER messages on the STa and SWa interfaces

Table 1.3. DIAMETER messages on the S6b interface

Table 1.4. DIAMETER messages on the SWm interface

Table 1.5. DIAMETER messages on the Gx, Gxa and Gxb interfaces

Chapter 2 MAC Layer

Table 2.1. To DS and From DS subfield values

Table 2.2. Meaning of Address fields

Table 2.3. Correspondence between the priority levels and the access categories

Table 2.4. Default values of EDCA parameters

Chapter 3 802.11a/g Interfaces

Table 3.1. Rates of DATA field

Table 3.2. Parameters of the modulation and coding scheme

Table 3.3. Values of the duration of the different parameters

Table 3.4. Parameters of OFDM multiplexing

Table 3.5. U-NII band at 5 GHz

Table 3.6. European regulations

Chapter 4 802.11n Interface

Table 4.1. Features of MAC layer

Table 4.2. Information of HT Capabilities Info field

Table 4.3. Information of Link Adaptation Control field

Table 4.4. HT-SIG field structure

Table 4.5. Characteristics of PMD sub-layer

Table 4.6. OFDM multiplexing parameters

Table 4.7. Parameters of the modulation and coding scheme 20 MHz bandwidth

Table 4.8. Parameters of the modulation and coding scheme 40 MHz bandwidth

Table 4.9. MCS 32 parameters

Chapter 5 802.11ac Interface

Table 5.1. Subfields of the VHT Capabilities Info field

Table 5.2. Subfields of Control Middle field

Table 5.3. Structure of VHT-SIG-A field

Table 5.4. Parameters of the modulation and coding scheme – Bandwidth of 20 MHz

Table 5.5. Parameters of the modulation and coding scheme – Bandwidth of 40 MHz

Table 5.6. Parameters of the modulation and coding scheme – Bandwidth of 80 MHz

Table 5.7. Parameters of the modulation and coding scheme Bandwidth of 160 MHz and 80+80 MHz

Chapter 7 SWu Tunnel Establishment

Table 7.1. Block types

Chapter 8 S2a/S2b Tunnel Establishment

Table 8.1. GTPv2-C messages

Table 8.2. Data transfer: CN to MN

Chapter 9 S2c Tunnel Establishment

Table 9.1. Correspondence table between the HoA and CoA addresses

Table 9.2. Correspondence table between the BID and FID identifiers

Chapter 10 Network Discovery and Selection

Table 10.1. ANQP information elements

Chapter 12 MPTCP Aggregation

Table 12.1. ECN field in IP header

Table 12.2. MPTCP options

List of Illustrations

Introduction

Figure I.1. 4G mobile network architecture

Figure I.2. Bearer establishment

Figure I.3. Wi-Fi network architecture

Figure I.4. Protocol architecture

Figure I.5. Session establishment – Architecture based on S2a interface

Figure I.6. Session establishment – Architecture based on S2b interface

Figure I.7. Session establishment – Architecture based on S2c interface

Figure I.8. Wi-Fi and LTE access aggregation

Chapter 1 Architecture Based on Wi-Fi Access

Figure 1.1. Functional architecture based on the S2a interface

Figure 1.2. Connection to the PDN network for architecture based on the S2a interface

Figure 1.3. Functional architecture based on the S2b interface

Figure 1.4. Connection to the PDN network for architecture based on S2b interface

Figure 1.5. Functional architecture based on S2c interface Trusted Wi-Fi access

Figure 1.6. Functional architecture based on S2c interface Untrusted Wi-Fi access

Figure 1.7. Protocol architecture based on S2a interface Control plane for PMIPv6 mechanism

Figure 1.8. Protocol architecture based on S2a interface User plane for PMIPv6 mechanism

Figure 1.9. Protocol architecture based on S2a interface Control plane for MIPv4 FA mechanism

Figure 1.10. Protocol architecture based on S2a interface User plane for MIPv4 FA mechanism

Figure 1.11. Protocol architecture based on S2a interface Control plane for GTPv2 mechanism

Figure 1.12. Protocol architecture based on S2a interface User plane for GTPv2 mechanism

Figure 1.13. Protocol architecture based on S2b interface Control plane for PMIPv6 mechanism

Figure 1.14. Protocol architecture based on S2b interface User plane for PMIPv6 mechanism

Figure 1.15. Protocol architecture based on S2c interface Control plane for trusted Wi-Fi access

Figure 1.16. Protocol architecture based on S2c interface User plane for trusted Wi-Fi access

Figure 1.17. AAA server interfaces using the DIAMETER protocol

Figure 1.18. PCRF interfaces using the DIAMETER protocol

Chapter 2 MAC Layer

Figure 2.1. MAC header structure

Figure 2.2. Structure of control frames

Figure 2.3. Structure of the BEACON management frame

Figure 2.4. Structure of the AUTHENTICATION management frame

Figure 2.5. Structure of management frames relating to the association phase

Figure 2.6. Structure of the management frames DISASSOCIATION and DEAUTHENTICATION

Figure 2.7. Active scanning

Figure 2.8. Use of control frames for data transfer

Figure 2.9. Backoff mechanism

Figure 2.10. Duration field for RTS and CTS control frames

Figure 2.11. Duration field for ACK control frame

Figure 2.12. Duration field for the PS-POLL control frame

Figure 2.13. Frame fragmentation

Figure 2.14. Standby management

Figure 2.15. Format of WEP encapsulation

Figure 2.16. WEP processing of the transmission chain

Figure 2.17. WEP processing of the reception chain

Figure 2.18. Format of TKIP encapsulation

Figure 2.19. TKIP processing of the transmission chain

Figure 2.20. TKIP processing of the reception chain

Figure 2.21. Format of CCMP encapsulation

Figure 2.22. CCMP processing of the transmission chain

Figure 2.23. CCMP processing of the reception chain

Figure 2.24. Evolution of MAC header structure

Chapter 3 802.11a/g Interfaces

Figure 3.1. Format of PLCP frame

Figure 3.2. Transmission and reception chain

Figure 3.3. Scrambler diagram

Figure 3.4. Convolutional encoder diagram

Figure 3.5. Structure of the preamble and OFDM symbols

Figure 3.6. PLCP frame for ERP-HR / DSSS mode

Figure 3.7. PLCP frame for ERP-OFDM mode

Figure 3.8. PLCP frame for DSSS-OFDM mode

Figure 3.9. ISM band at 2.4 GHz

Chapter 4 802.11n Interface

Figure 4.1. Structure of MAC header

Figure 4.2. Structure of A-MPDU frame

Figure 4.3. Structure of A-MSDU frame

Figure 4.4. Block acknowledgment

Figure 4.5. Control frame structure

Figure 4.6. PLCP frame structure

Figure 4.7. Transmission chain – Diagram 1

Figure 4.8. Transmission chain – Diagram 2

Figure 4.9. Frequency plan

Figure 4.10. MIMO mechanism

Figure 4.11. STBC mechanism

Figure 4.12. Beamforming mechanism

Chapter 5 802.11ac Interface

Figure 5.1. Bandwidth negotiation

Figure 5.2. MAC header structure

Figure 5.3. PLCP frame structure

Figure 5.4. Generation of L-SIG and VHT-SIG-A fields

Figure 5.5. Generation of VHT-SIG-B field – Data unit for a single user Radio channel bandwidths of 20, 40, and 80 MHz

Figure 5.6. Generation of VHT-SIG-B field – Data unit for multi-user Radio channel bandwidths of 20, 40, and 80 MHz

Figure 5.7. Generation of VHT-SIG-B field – Data unit for a single user Radio channel bandwidth of 160 MHz

Figure 5.8. Generation of VHT-SIG-B field – Data unit for a single user Radio channel bandwidth of 80+80 MHz

Figure 5.9. Generation of DATA field – Data unit for a single user BCC encoder – Radio channel bandwidths of 20, 40 and 80 MHz radio

Figure 5.10. Generation of DATA field – Data unit for a single user LDPC encoder – Radio channel bandwidths of 20, 40 and 80 MHz radio

Figure 5.11. Generation of DATA field – Data unit for multi-user Radio channel bandwidths of the of 20, 40 and 80 MHz

Figure 5.12. Generation of DATA field – Data unit for a single user BCC encoder – Radio channel bandwidth of the 160 MHz

Figure 5.13. Generation of DATA field – Data for a single user LDPC encoder – Radio channel bandwidth of the 160 MHz

Figure 5.14. Generation of DATA field – Data unit for a single user BCC encoder – Radio channel bandwidth of 80 + 80 MHz

Figure 5.15. Generation of DATA field – Data unit for a single user LDPC encoder – Radio channel bandwidth of 80 + 80 MHz

Figure 5.16. Frequency plan Channel bandwidths of 20, 40, 80 and 160 MHz

Figure 5.17. Frequency plan Channel bandwidths of 80+80 MHz

Figure 5.18. SU-MIMO and MU-MIMO mechanism

Chapter 6 Mutual Authentication

Figure 6.1. Components of 802.1x mechanism

Figure 6.2. Protocol architecture for 802.1x mechanism

Figure 6.3. Structure of EAPOL message

Figure 6.4. EAP message structure

Figure 6.5. Common exchanges in the authentication procedure

Figure 6.6. Four-way handshake procedure

Figure 6.7. Group key handshake procedure

Figure 6.8. Mutual authentication procedure

Figure 6.9. Procedure for rapid renewal of authentication

Chapter 7 SWu Tunnel Establishment

Figure 7.1. AH extension format

Figure 7.2. ESP extension format

Figure 7.3. Position of AH extension

Figure 7.4. Position of ESP extension

Figure 7.5. IKE message header format

Figure 7.6. Format of generic block header

Figure 7.7. IKE_SA_INIT exchange

Figure 7.8. IKE_AUTH exchange

Figure 7.9. CREATE_CHILD_SA exchange creation of ESP/AH SA

Figure 7.10. CREATE_CHILD_SA exchange renewal of IKE SA key

Figure 7.11. CREATE_CHILD_SA exchange renewal of ESP/AH SA key

Figure 7.12. SWu tunnel establishment procedure

Figure 7.13. Procedure for rapid renewal of authentication

Chapter 8 S2a/S2b Tunnel Establishment

Figure 8.1. PMIPv6 architecture

Figure 8.2. Mobile node attachment to the LMA function IPv6 configuration

Figure 8.3. MAG function change

Figure 8.4. S2a tunnel establishment using PMIPv6 mechanism

Figure 8.5. S2b tunnel establishment using PMIPv6 mechanism

Figure 8.6. S2a tunnel establishment using GTPv2 mechanism

Figure 8.7. Components of mobility

Figure 8.8. Data transfer

Figure 8.9. S2a tunnel establishment using MIPv4 FA mechanism

Chapter 9 S2c Tunnel Establishment

Figure 9.1. Components for MIPv6 mechanism

Figure 9.2. Mobility extension format

Figure 9.3. Attachment of the mobile node to the home agent

Figure 9.4. Data transfer

Figure 9.5. Network change of the mobile node

Figure 9.6. Return of the mobile node to the host network

Figure 9.7. Return Routability procedure

Figure 9.8. S2c tunnel establishment Trusted Wi-Fi access

Figure 9.9. S2c tunnel establishment Untrusted Wi-Fi access

Chapter 10 Network Discovery and Selection

Figure 10.1. ANDI information

Figure 10.2. ISMP policy

Figure 10.3. IFOM rules

Figure 10.4. MAPCOM rules

Figure 10.5. NSWO rules

Figure 10.6. IARP rules

Figure 10.7. WLANSP policy

Figure 10.8. Wi-Fi access network preferences

Figure 10.9. GAS/ANQP exchanges

Chapter 11 Carrier Aggregation

Figure 11.1. Functional architecture for LTE and Wi-Fi carrier aggregation

Figure 11.2. Protocol architecture for LWA aggregation eNB and AP entities are collocated

Figure 11.3. Protocol architecture for LWA aggregation eNB and AP entities are distant

Figure 11.4. Protocol architecture for LWIP aggregation

Figure 11.5. WT Addition procedure

Figure 11.6. WT Modification procedure initiated by the eNB entity

Figure 11.7. WT Modification procedure initiated by the access point

Figure 11.8. WT Release procedure initiated by the eNB entity

Figure 11.9. WT Release procedure initiated by the access point

Figure 11.10. LWIP and IPSec tunnel establishment

Figure 11.11. LBT mechanism –FBE option

Figure 11.12. LBT mechanism –LBE option

Figure 11.13. PDCP frame structure containing IP packets or RRC messages

Figure 11.14. PDCP frame structure containing Status Report messages

Chapter 12 MPTCP Aggregation

Figure 12.1. Architecture for MPTCP aggregation

Figure 12.2. Format of TCP header

Figure 12.3. Slow Start and Congestion Avoidance mechanisms

Figure 12.4. Fast Retransmit and Fast Recovery mechanisms

Figure 12.5. ECN field in IP header

Figure 12.6. ECN field in TCP header

Figure 12.7. Format of MPTCP option

Figure 12.8. Establishment of an MPTCP connection

Figure 12.9. Adding a TCP connection

Figure 12.10. Data transfer

Figure 12.11. Closing a MPTCP connection

Figure 12.12. Abrupt closure of MPTCP connection

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e1

Wi-Fi Integration to the 4G Mobile Network

André Perez

First published 2018 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:

ISTE Ltd27-37 St George’s RoadLondon SW19 4EUUK

www.iste.co.uk

John Wiley & Sons, Inc.111 River StreetHoboken, NJ 07030USA

www.wiley.com

© ISTE Ltd 2018The rights of André Perez to be identified as the author of this work have been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.

Library of Congress Control Number: 2018931217

British Library Cataloguing-in-Publication DataA CIP record for this book is available from the British LibraryISBN 978-1-78630-173-4

List of Abbreviations

3GPP

3rd Generation Partnership Project

A

AAA

Authentication Authorization Accounting

AAA

Authenticate and Authorize Answer

AAD

Additional Authentication Data

AAR

Authenticate and Authorize Request

AC

Access Category

ACK

Acknowledgment

AES

Advanced Encryption Standard

AF

Application Function

AGC

Automatic Control Gain

AH

Authentication Header

AID

Association Identifier

AIFS

Arbitration Inter-Frame Space

AKA

Authentication and Key Agreement

AM

Acknowledgement Mode

A-MPDU

Aggregate MAC Protocol Data Unit

A-MSDU

Aggregate MAC Service Data Unit

ANDI

Access Network Discovery Information

ANDSF

Access Network Discovery and Selection Function

ANQP

Access Network Query Protocol

AP

Access Point

APN

Access Point Name

ARP

Address Resolution Protocol

ASA

Abort-Session-Answer

ASR

Abort-Session-Request

AUTN

Authentication Network

B

BCC

Binary Convolutional Coding

BCE

Binding Cache Entry

BID

Binding Identifier

BPSK

Binary Phase-Shift Keying

BSS

Basic Service Set

BSSID

BSS Identifier

C

CCA

Credit-Control-Answer

CCA

Clear Channel Assessment

CCK

Complementary Code Keying

CCMP

Counter-mode/CBC-MAC-Protocol

CCR

Credit-Control-Request

CE

Congestion Experienced

CHAP

Challenge Handshake Authentication Protocol

CK

Cipher Key

CN

Correspondent Node

CNA

Correspondent Node Address

CoA

Care-of Address

CoT

Care-of Test

CoTI

Care-of Test Init

CRC

Cyclic Redundancy Check

CSD

Cyclic Shift Diversity

CSMA/CA

Carrier Sense Multiple Access/Collision Avoidance

CTS

Clear To Send

CW

Contention Window

CWR

Congestion Window Reduced

D

DA

Destination Address

DAD

Duplicate Address Detection

DCF

Distributed Coordination Function

DEA

Diameter-EAP-Answer

DER

Diameter-EAP-Request

DF

Don’t Fragment

DFS

Dynamic Frequency Selection

DHCP

Dynamic Host Configuration Protocol

DIFS

DCF Inter-Frame Space

DNS

Domain Name System

DOI

Domain of Interpretation

DRB

Data Radio Bearer

DSCP

DiffServ Code Point

DSMIPv6

Dual-Stack Mobile IP version 6

DSS

Data Sequence Signal

DSSS

Direct Sequence Spread Spectrum

E

EAP

Extensible Authentication Protocol

EAPOL

EAP Over LAN

ECE

ECN-Echo

ECN

Explicit Congestion Notification

ECT

ECN-Capable Transport

EDCA

Enhanced Distributed Channel Access

EHSP

Equivalent Home Service Providers

EIFS

Extended Inter-Frame Space

EMSK

Extended Master Session Key

eNB

evolved Node B station

EPC

Evolved Packet Core

ePDG

evolved Packet Data Gateway

EPS

Evolved Packet System

E-RAB

EPS Radio Access Bearer

ERP

Extended Rate Physical

ESP

Encapsulating Security Payload

ESS

Extended Service Set

E-UTRAN

Evolved Universal Terrestrial Radio Access Network

F

FA

Foreign Agent

FAA

Foreign Agent Address

FBE

Frame-Based Equipment

FCS

Frame Check Sequence

FID

Flow Identifier

FQDN

Fully Qualified Domain Name

G

GAS

Generic Advertisement Service

GEK

Group Encryption Key

GI

Guard Interval

GIK

Group Integrity Key

GPRS

General Packet Radio Service

GRE

Generic Routing Encapsulation

GTP-C

GPRS Tunnel Protocol Control

GTP-U

GPRS Tunnel Protocol User

H

HA

Home Agent

HESSID

Homogeneous Extended Service Set Identifier

HNP

Home Network Prefix

HoA

Home Address

HoT

Home Test

HoTI

Home Test Init

HR

High Rate

HS2.0

Hotspot 2.0

HSS

Home Subscriber Server

HT

High Throughput

I

IARP

Inter-APN Routing Policy

ICMP

Internet Control Message Protocol

ICV

Integrity Check Value

IDFT

Inverse Discrete Fourier Transform

IE

Information Element

IEEE

Institute of Electrical and Electronics Engineers

IETF

Internet Engineering Task Force

IFOM

IP Flow Mobility

IK

Integrity Key

IKEv2

Internet Key Exchange version 2

IMSI

International Mobile Subscriber Identity

IP

Internet Protocol

IPSec

IP Security

ISAKMP

Internet Security Association and Key Management Protocol

ISM

Industrial, Scientific and Medical

ISMP

Inter-System Mobility Policy

ISRP

Inter-System Routing Policy

IV

Initialization Vector

K, L

KCK

Key Confirmation Key

KEK

Key Encryption Key

LAA

Licensed Assisted Access

LAN

Local Area Network

LBE

Load-Based Equipment

LBT

Listen Before Talk

LCID

Logical Channel Identifier

LDPC

Low-Density Parity Check

LLC

Logical Link Control

LMA

Local Mobility Anchor

LMAA

LMA Address

LMD

Local Mobility Domain

LTE

Long-Term Evolution

LTF

Long Training Field

LWA

LTE-Wi-Fi Aggregation

LWAAP

LWA Adaptation Protocol

LWIP

LTE/WLAN radio level integration with IPsec tunnel

LWIPEP

LWIP Encapsulation Protocol

M

MAA

Multimedia-Authentication-Answer

MAC

Medium Access Control

MAC

Message Authentication Code

MAG

Mobile Access Gateway

MAPCON

Multiple-Access PDN Connectivity

MAR

Multimedia-Authentication-Request

MCC

Mobile Country Code

MIC

Message Integrity Code

MIMO

Multiple Input Multiple Output

MIP

Mobile IP

MME

Mobility Management Entity

MN

Mobile Node

MNC

Mobile Network Code

MO

Management Object

MPTCP

Multi-Path Transmission Control Protocol

MSDU

MAC Service Data Unit

MSISDN

Mobile Subscriber ISDN Number

MSK

Master Session Key

MSS

Maximum Segment Size

MU

Multi User

N, O

NAI

Network Access Identifier

NAS

Non-Access Stratum

NAT

Network Address Translation

ND

Neighbor Discovery

NSWO

Non-Seamless WLAN Offload

OCS

Online Charging System

OFCS

Offline Charging System

OFDM

Orthogonal Frequency-Division Multiplexing

OPI

Offload Preference Indication

OSA

Open System Authentication

P

PAD

Peer Authorization Database

PBA

Proxy Binding Acknowledgement

PBCC

Packet Binary Convolutional Code

PBU

Proxy Binding Update

PCC

Policy and Charging Control

PCO

Phased Coexistence Operation

PCRF

Policy Charging and Rules Function

PDCP

Packet Data Convergence Protocol

PDN

Packet Data Network

PGW

PDN Gateway

PLCP

Physical Layer Convergence Protocol

PMD

Physical Medium Dependent

PMIPv6

Proxy Mobile IP version 6

PMK

Pairwise Master Key

PN

Packet Number

PPA

Push-Profile-Answer

PPDU

PLCP Protocol Data Unit

PPR

Push-Profile-Request

PS

Packet-Switched

PS

Power Save

PSDU

PLCP Service Data Unit

PSPL

Preferred Service Provider List

PTK

Pairwise Transient Key

Q, R

QAM

Quadrature Amplitude Modulation

QoS

Quality of Service

QPSK

Quadrature Phase-Shift Keying

RA

Receiver Address

RA

Router Advertisement

RAA

Re-Auth-Answer

RADIUS

Remote Authentication Dial-In User Service

RAR

Re-Auth-Request

RC4

Rivest Cipher

RD

Reverse Direction

RFC

Request For Comments

RIFS

Reduced Inter-Frame Space

RLC

Radio Link Control

ROHC

Robust Header Compression

RRC

Radio Resource Control

RSN

Robust Security Network

RSRP

Reference Signal Received Power

RSSI

Received Signal Strength Indication

RTA

Registration-Termination-Answer

RTO

Retransmission Time Out

RTR

Registration-Termination-Request

RTS

Request To Send

RTT

Round Trip Time

S

SA

Source Address

SA

Security Association

SAA

Server-Assignment-Answer

SACK

Selective Acknowledgment

SAD

Security Association Database

SAR

Server-Assignment-Request

SeGW

Security Gateway

SGW

Serving Gateway

SIFS

Short Inter-Frame Space

SKA

Shared Key Authentication

SPD

Security Policy Database

SPI

Security Parameter Index

SPR

Subscription Profile Repository

SSID

Service Set Identifier

ST

Slot Time

STA

Session Termination Answer

STBC

Space-Time Block Coding

STF

Short Training Field

STR

Session Termination Request

SU

Single User

T

TA

Transmitter Address

TAI

Tracking Area Identity

TC

Traffic Class

TCP

Transmission Control Protocol

TEID

Tunnel Endpoint Identifier

TFT

Traffic Flow Template

TID

Traffic Identifier

TIM

Traffic Indication Map

TK

Temporary Key

TKIP

Temporal Key Integrity Protocol

TLS

Transport Layer Security

TLV

Type, Length, Value

TMK

Temporary MIC Key

TPC

Transmit Power Control

TSC

TKIP Sequence Counter

TTAK

TKIP-mixed Transmit Address and Key

TTL

Time To Live

TTLS

Tunneled Transport Layer Security

TWAG

Trusted WLAN Access Gateway

TWAN

Trusted WLAN Access Network

TWAP

Trusted WLAN AAA Proxy

TXOP

Transmission Opportunity

U

UDP

User Datagram Protocol

UE

User Equipment

UICC

Universal Integrated Circuit Card

U-NII

Unlicensed-National Information Infrastructure

UP

User Priority

USIM

Universal Services Identity Module

V, W, X

VHT

Very High Throughput

VoLTE

Voice over LTE

WEP

Wired Equivalent Privacy

WFA

Wi-Fi Alliance

Wi-Fi

Wireless Fidelity

WLAN

Wireless Local Area Network

WLCP

WLAN Control Plane

WPA

Wi-Fi Protected Access

WRED

Weighed Random Early Discard

XML

eXtensible Markup Language

Introduction

The proliferation of mobile applications has increased the amount of data in the 4G mobile network. With the adoption of smartphones and broadband services, such as video streaming, cellular network resources are increasingly constrained.

Wi-Fi technology is ideally positioned to add capacity to the cellular network. It is necessary to improve the interworking between the 4G mobile network and the Wi-Fi network in order to offer a global and consistent broadband access to the end-user.

In addition to growing traffic, users expect unrestricted access to applications whether at home, in a business or on the road. For this reason, Wi-Fi technology, providing additional coverage, is an appropriate solution for roaming users.

The ability to exploit unlicensed frequency bands in addition to the spectrum allocated to cellular networks is of obvious appeal to network operators, who see Wi-Fi as another means of accessing the 4G mobile network.

Many mobile phones currently sold include both cellular and Wi-Fi radio access and are capable of simultaneously using both radios. This makes it possible to direct certain services to Wi-Fi access and others to the cellular radio access.

The various standardization bodies, IEEE (Institute of Electrical and Electronics Engineers), WFA (Wi-Fi Alliance) and 3GPP (3rd Generation Partnership Project), paved the way for the integration of Wi-Fi technology into the cellular network, allowing the mobile to access its services through Wi-Fi access.

I.1. 4G mobile network

I.1.1. Network architecture

The 4G mobile network, which is called EPS (Evolved Packet System), consists of an evolved packet core (EPC) and an evolved universal terrestrial radio access network (E-UTRAN) (Figure I.1).

The E-UTRAN access network provides the connection of the user equipment (UE). The core network EPC interconnects access networks, provides the interface to the packet data network (PDN) and provides mobile attachment and bearer establishment.

Figure I.1.4G mobile network architecture

The evolved node B station (eNB) compresses and encrypts traffic data on the radio interface, as well as encrypts and checks the integrity of signaling data exchanged with the mobile.

The mobility management entity (MME) allows mobile access to the EPS network and controls the establishment of bearers for the transmission of traffic data.

The SGW (Serving Gateway) entity is the anchor point for intra-system handover (mobility within the 4G network) and inter-system handover in packet-switched (PS) mode, requiring transfer of mobile traffic to a secondor third-generation mobile network.

The PGW (PDN Gateway) entity is the gateway router that connects the EPS network to the PDN. It provides the mobile with its configuration (IP address) and traffic information to the online charging system (OCS) for the prepaid and offline charging system (OFCS) for the postpaid.

The home subscriber server (HSS) is a database that stores data specific to each subscriber. The main stored data include subscriber identities, authentication parameters and service profile.

The policy charging and rules function (PCRF) provides the PGW entity with the rules to apply for the traffic (rate, quality of service, charging mode) when establishing the bearer. This information is stored in the subscription profile repository (SPR) when the subscription is created.

I.1.2. Security architecture

The mutual authentication between the mobile and the MME entity is based on the EPS-AKA (Authentication and Key Agreement) mechanism:

– the HSS entity provides the MME entity with the authentication vector (RAND, AUTN, RES, K

ASME

) from the secret key Ki created during the subscription of the mobile;

– the MME entity provides the mobile with the random number (RAND) and the seal (AUTN) of the network;

– the mobile calculates the seals (AUTN, RES) and the key K

ASME

from its key Ki stored in the universal subscriber identity module (USIM) of its universal integrated circuit card (UICC) and compares the seal (AUTN) received with that calculated;

– the mobile transmits its seal (RES) to the MME entity, which compares it to that received from the HSS entity;

– the K

ASME

key is used to protect the signaling exchanged between the mobile and the MME entity as well as the control and traffic data on the radio interface.

I.1.3. Bearer establishment

The EPS network transports the mobile data stream (IP packets) transparently to the PGW entity that is routing the packets. The IP packet is transported in bearers built between the entities of the EPS network (Figure I.2).

Figure I.2.Bearer establishment

The data radio bearer (DRB) is built between the mobile and the eNB entity. The RRC (Radio Resource Control) signaling, exchanged between the mobile and the eNB entity, is responsible for the construction of this bearer.

The S1 bearer is built between the eNB and SGW entities. The S1-AP signaling, exchanged between the eNB and MME entities, and the GTPv2 (GPRS Tunneling Protocol-Control) signaling, exchanged between the MME and SGW entities, are responsible for the construction of this bearer.

The S5 bearer is built between the SGW and PGW entities. The GTPv2-C signaling, exchanged between the SGW and PGW entities, is responsible for the construction of this bearer.

The connection of the radio bearer and the S1 bearer, carried out by the eNB entity, constitutes the EPS radio access bearer (E-RAB).

The connection of the E-RAB and S5 bearers, made by the SGW entity, constitutes the EPS bearer.

The S1 and S5 bearers are GTP-U (GPRS Tunneling Protocol User) tunnels, which allow the IP packet of the mobile to be transported in the IP packet of the bearer transmitted between the entities of the EPS network.

The PGW entity is the only entity in the EPS network that routes the mobile IP packet. The IP transport network that allows communication between the entities of the EPS network routes the IP packet that is the S1 or S5 bearer. The eNB and SGW entities do not perform routing. They only provide the connection between the bearers.

I.2. Wi-Fi network

I.2.1. Network architecture

The Wi-Fi (Wireless Fidelity) network consists of an access point (AP) that bridges the Wi-Fi radio interface with the Ethernet interface to the local area network (LAN) (Figure I.3).

Figure I.3.Wi-Fi network architecture

The BSS (Basic Service Set) cell is the radio zone covered by the access point. The BSS identifier (BSSID) of the BSS cell is the MAC address of the access point.

Several BSS cells can be deployed to cover an area. The set of cells constitute an ESS (Extended Service Set) network. The ESS network is identified by the service set identifier (SSID).

Wi-Fi technology has defined the data link layer and physical layer of the radio interface (Figure I.4):

– the data link layer consists of two sub-layers, namely the LLC (Logical Link Control) sub-layer and the MAC (Medium Access Control) sub-layer;

– the physical layer has defined two sub-layers, namely the PLCP (Physical Layer Convergence Protocol) sub-layer and the PMD (Physical Medium Dependent) sub-layer.

Bridging consists of modifying the data link layer and the physical layer used on both sides of the access point.

Figure I.4.Protocol architecture