MAP-Tele Manuel P. Ricardo -...

WNP-MPR-Fundaments 1

Wireless Networks and Protocols

MAP-Tele

Manuel P. Ricardo

Faculdade de Engenharia da Universidade do Porto


Professors

♦ Adriano Moreira (WNP Coordinator)

» Universidade do Minho

♦ Manuel P. Ricardo ([email protected])

» Faculdade de Engenharia, Universidade do Porto» Faculdade de Engenharia, Universidade do Porto

» [email protected]

» http://www.fe.up.pt/~mricardo

» Tel. 22 209 4200

♦ Rui L. Aguiar

» Universidade de Aveiro


Goals of the Course

The WNP course has two main objectives

» provide competences to understand current wireless networks and their functions

» provide competences required to create future wireless networks and their functions


Syllabus

♦ Introduction to Wireless Networks and Protocols

» What are Wireless networks

» History of wireless networks

» Standards and market issues

» Evolution and trends on wireless networking» Evolution and trends on wireless networking

♦ Fundamentals of wireless communications

» Transmission

» Wireless data links and medium access control

» Networking

» Mobility concepts and management

» Research issues


Syllabus

♦ Telecommunications systems

» GSM and GPRS

» UMTS

» TETRA

» Broadcast and satellite: DVB, DMB

♦ IEEE wireless data networks

5

♦ IEEE wireless data networks

» WLAN: 802.11

» WMAN: 802.16

» WPAN: 802.15

♦ Convergence and interoperability of wireless systems

» 4G wireless networks

» 3GPP and Mobile IPv6 approaches

» Integration of ad-hoc networks

» Research issues


Syllabus

♦ Quality of service

» Characterization and models

» Case studies: 3GPP-QoS, IEEE-QoS, IP-QoS

» Research issues

6

♦ Support for services and applications

» Web services components: XML and SOAP, UDDI and WSDL

» Services and applications platforms

» Research issues


Bibliography

♦ Handouts

♦ Recommended papers

♦ Chapters from multiple books» Wireless and Mobile Network Architectures, Yi-Bing Lin, Imrich Chlamtac Wiley, 2001

» Wireless IP and Building the Mobile Internet, Sudhir Dixit, Ramjee Prasad, Artech House, 2002.

» The 3G IP Multimedia Subsystem, Merging the Internet and the Cellular Worlds, Gonzalo Camarillo and Miguel a. Garcia-Martin,Wiley, Second Edition, 2005

» Ad-hoc Wireless Networks, Architectures and Protocols, C. Silva Murthy, B. Manoj, Prentice Hall, 2004

7

» Ad-hoc Wireless Networks, Architectures and Protocols, C. Silva Murthy, B. Manoj, Prentice Hall, 2004

» Advanced Wireless Networks - 4G Technologies, S. Glisic, Wiley, 2006.

» Mobile Communications, Jochen Schiller, Second Edition, Addison-Wesley, 2003

» Wireless Communications - Principles and Practice, Theodore S. Rappaport, Second Edition, Prentice Hall, 2002

» Mobile IP Technology and Applications, Stefan Raab and Madhavi W. Chandra, Cisco Press, 2005

» GSM cellular radio telephony, Joachim Tisal, John Wiley & Sons, 1997

» Wireless Communications and Networks, William Stallings, Prentice Hall, 2002

» WCDMA for UMTS : radio acess for third generation mobile communications, Harri Holma, John Wiley & Sons, 2000

» UMTS networks : architecture, mobility and services, Heikki Kaaranen, et al, John Wiley & Sons, 2001


Evaluation

♦ Final Exam - 40%

♦ Review of 3 papers - 30%

8

♦ Small project - 30%


Topics Scheduled for Today


♦ Fundamentals of wireless communications

» Transmission

Next week

» Wireless data links and medium access control

» Networking

» Mobility concepts and management

» Research issues

Today


Mobile vs Fixed networks

♦ Mobile communications systems characterised by

» wireless links

» mobility of terminals

T

switch

AP

TAP

1

2

1

2

Terminal

Mobility

Computer Switch

Computer AP

Wireless link

Wired link


Wireless Link

• Susceptible to noise• Susceptible to noise

Ł large % of bits received in error

• Broadcast nature

– Demands security mechanisms

– Adequate for broadcast services


To Think About

How to obtain a low Bit Error Ratio (BER) in a wireless link?


Today

Transport

Application

Physical

Network

Data link

Mo

bil

ity

Sec

uri

ty

Mu

ltic

ast

Qu

ali

ty o

f S

ervi

ce


Wireless Data Link

and and

Medium Access Control



A. The Basic Framework


♦ Fundamentals of wireless communications (brief overview)

» Transmission

» Wireless data links and medium access control » Wireless data links and medium access control

» Networking

» Why wireless? Mobility concepts and management

» Research issues

B. The Existing Practices and Concepts

» …


♦ How to transmit signals in both directions simultaneously?

♦ How to enable multiple users to communicate simultaneously?


Radio Link Model

♦ Wireless physical layer

» provides virtual link of unreliable bits

» service described in terms of

Gross bit rate – R, r (bit/s)

Bit error ratio – BER, e

Tx Rcv

♦ In absence of link adaptation

» R constant

» BER absorbs channel variability

♦ Using link adaptation techniques

» BER usually kept bounded

» R changes

0 1 2 M-1…

λ0

µ1

λ1

µ2

λ2

µ3

λΜ−2

µΜ−1

r0 e0 r1 e1 r2 e2 rM-1 eM-1

Adaptive Transmitter

Physical layer


Duplex Transmission

♦ Duplex – transference of data in both directionsUplink and Downlink channels required

♦ Two methods for implementing duplexing♦ Two methods for implementing duplexing

» Frequency-Division Duplexing (FDD)

– wireless link split into frequency bands

– bands assigned to uplink or downlink directions

– peers communicate in both directions using different bands

» Time-Division Duplexing (TDD)

– timeslots assigned to the transmitter of each direction

– peers use the same frequency band but at different times


Duplex Transmission


To Think About

♦ How to place several sender-receiver pairs communicating in the

same physical space?same physical space?


Multi-Access Schemes

♦ Multi-access schemes

» Identify radio resources

» Assign resources to multiple users/terminals

♦ Multi-access schemes ♦ Multi-access schemes

» Frequency-Division Multiple Access (FDMA)

resources divided in portions of spectrum (channels)

» Time-Division Multiple Access (TDMA)

resources divided in time slots

» Code-Division Multiple Access (CDMA)

resources divided in codes

» Space-Division Multiple Access (SDMA)

resources divided in areas


FDMA

» Signal space divided along the frequency axis

into non-overlapping channels

» Each user assigned a different frequency channel

» The channels often have guard bands

» Transmission is continuous over time

channel k

channel 2

time

co

de

channel 1


TDMA

» Signal space divided along the time axis

into non-overlapping channels

» Each user assigned a different cyclically-repeating timeslot

» Transmission not continuous for any user

» Major problem

synchronization among the users in the uplink channels

users transmit over channels having different delays

uplink transmitters must synchronize

timeco

de

… …


CDMA

♦ Each user assigned a code to spread his information signal

» Multi-user spread spectrum (Direct Sequence, Frequency Hopping)

» The resulting spread signal– occupy the same bandwidth

– transmitted at the same time

co

de

♦ Different bitrates to users

Ł control length of codes

♦ Power control required in uplink

» to compensate near-far effect

» If not, interference from close user swamps signal from far user

time

channel 1

channel 2

channel k

…


SDMA

♦ SDMA uses direction (angle) to assign channels to users

♦ Implemented using sectorized antenna arrays

» the 360º angular range divided in N sectors

» TDMA or FDMA then required to channelize users

♦ Cellular division of the space

» is also SDMA

BS

MT-1

MT-2

MT-k


Combined Multi-access Techniques

♦ Current technologies Ł combinations of multi-access techniques

» GSM: FDMA and then TDMA to assign slots to users

♦ The cell concept Ł combined multi-access technique

» SDMA + FDMA

♦ Cellular planning♦ Cellular planning

f1

f3

f3

f2

f2

f1

f3

f1

f3

f3

f2

f2

f1

f3

f1

f3

f3

f2

a) Group of 3 cells

f4

f2

f6

f3

f5

f2

f1

f6

f3

f5

f7

f2

f3

f4

f5

f7

f2

f1

b) Group of 7 cells c) Group of 3 cells, each having 3 sectors

f2

f3f1

f2

f3f1

f2

f3f1

f5

f6f4

f5

f6f4

f8

f9f7

f8

f9f7

f8

f9f7


Wireless Medium Access Control Issues

♦ Medium Access Control (MAC)

» Assign radio resources to terminals along the time

♦ 3 type of resource allocation methods

» dedicated assignment» dedicated assignment

resources assigned in a predetermined, fixed, mode

» random access

terminals contend for the channel

» demand-based

terminals ask for reservations

using dedicated/random access channels


Hidden, Exposed and Capture Nodes

♦ Signal strength decays with the path length

♦ Carrier sensing depends on the position of the receiver

♦ MAC protocols using carrier sensing Ł 3 type of nodes

» hidden nodes

– C is hidden to A

» exposed nodes

– C is exposed to B

» capture nodes

– D captures A

A CB

D


Hidden, Exposed and Capture Nodes

• Hidden node à C is hidden to A– A transmits to B; C cannot hear A

– If C hears the channel it thinks channel is idle; C starts transmitting Ł interferes with data reception at B

– In the range of receiver; out of the range of the sender

• Exposed node à C is exposed to B– B transmits to A; C hears B; C does not transmit; but C transmission would not interfere with A reception

– In the range of the sender; out of the range of the receiver

• Capture à D captures A– receiver can receive from two senders– receiver can receive from two senders

– A and D transmit simultaneously to B; but signal from D much higher than that from A

A CB

D


Alhoa, S-Alhoa, CSMA

♦ Alhoa ß Efficiency of 18 %if station has a packet to transmit

u transmits the packet

u waits confirmation from receiver (ACK)

u if confirmation does not arrive in round trip time, the station

computes random backofftime à retransmits packet

♦ Slotted Alhoa ß Efficiency of 37 %stations transmit just at the beginning of each time slot

♦ Carrier Sense Multiple Access (CSMA) ß Efficiency of 54 %– station listens the carrier before it sends the packet

– If medium busy à station defers its transmission

♦ ACK required for Alhoa, S-Alhoa and CSMA


CSMA/CD – Not Used in Wireless

♦ CDMA/Collision Detection ß Efficiency < 80%– station monitors de medium (carrier sense)

u medium free à transmits the packet

u medium busy à waits until medium is free à transmits packet

u if, during a round trip time, detects a collision

à station aborts transmission and stresses collision à station aborts transmission and stresses collision

(no ACK packet)

♦ Problems of CDMA/CD in wireless networksCarrier sensing

carrier sensing difficult for hidden terminal

Collision detection

near-end interference makes simultaneous transmission and reception difficult


To think about?

♦ How to minimize collision in a wireless medium?


CSMA with Collision Avoidance (CSMA/CA)

S2

DIFS

S1DATA

DIFS S2-bo

DATA

S3

DIFS S3-bo

S3-bo-e S3-bo-r

DIFSS3-bo-r

DATA

- Packet arrivalDATA

- Transmission of DATA DIFS - Time interval DIFS S2-bo - Backoff time, station 2

- Elapsed backoff time, station 3S3-bo-e S3-bo-r

- Remaining backoff time, station 3


CSMA with Collision Avoidance (CSMA/CA)

♦ Station with a packet to transmit monitors the channel activity until an idle period equal to a Distributed Inter-Frame Space (DIFS) has been observed

♦ If the medium is sensed busy a random backoff interval is selected. The backoff time counter is decremented as long as the selected. The backoff time counter is decremented as long as the channel is sensed idle, stopped when a transmission is detected on the channel, and reactivated when the channel is sensed idle again for more than a DIFS. The station transmits when the backoff time reaches 0

♦ To avoid channel capture, a station must wait a random backoff time between two consecutive packet transmissions, even if the medium is sensed idle in the DIFS time


CSMA/CA – ACK Required

DIFS

S1

SIFS

DATA

ACK

SIFS

ACK

AP

S2

ACK

DIFS S2-Backoff

DATA

ACK


- Transmission of DATA DIFS - Time interval DIFS


CSMA/CA – ACK Required

♦ CSMA/CA does not rely on the capability of the stations to detect a collision by hearing their own transmission

♦ A positive acknowledgement is transmitted by the destination station to signal the successful packet transmission

♦ In order to allow an immediate response, the acknowledgement is transmitted ♦ In order to allow an immediate response, the acknowledgement is transmitted following the received packet, after a Short Inter-Frame Space (SIFS)

♦ If the transmitting station does not receive the acknowledge within a specified ACK timeout, or it detects the transmission of a different packet on the channel, it reschedules the packet transmission according to the previous backoff rules.

♦ Efficiency of CSMA/CA depends strongly of the number of competing stations. An efficiency of 60% is commonly found


To Think About

♦ How to enable hidden terminals to sense the carrier?

Hidden node àààà C is hidden to A

A CB

D


RTS-CTS Mechanism

DIFS

S1

SIFS

DATARTS

SIFS

SIFS

AP

S2

DIFS S2-bo

DATA


- Transmission of DATA DIFS - Time interval DIFS

CTS ACK


RTS-CTS Mechanism

♦ For some scenarios where long packets are used or the probability of hidden terminals is not irrelevant, the efficiency of CSMA/CA can be further improved with a Request To Send (RTS) - Clear to Send (CTS) mechanism

♦ The basic concept is that a sender station sends a short RTS message to the receiver station. When the receiver gets a RTS from the sender, it polls the sender by sending a short CTS message. The sender then sends its packet to the receiver. After correctly receiving the packet, the receiver sends a positive acknowledgement (ACK) to the senderreceiving the packet, the receiver sends a positive acknowledgement (ACK) to the sender

♦ This mechanism is particularly useful to transmit large packets. The listening of the RTS or the CTS messages enable the stations in range respectively of the sender or receiver that a big packet is about to be transmitted. Usually both the RTS and the CTS contain information about the number of slots required to transmit the 4 packets. Using this information the other stations refrain themselves to transmit packets, thus avoiding collisions and increasing the system efficiency.

♦ SIFS are used before the transmission of CTS, Data, and ACK

♦ In optimum conditions the RTS-CTS mechanism may add an efficiency gain of about 15%


Guaranteed Access Control

♦ Polling

» AP manages stations access to the medium

» Channel tested first using a control handshake


Fundamental NetworkingFundamental Networking






» Transmission

» Wireless data links and medium access control» Wireless data links and medium access control

» Networking


» Research issues


» …


♦ What networking concepts shall I have present from previous courses?

♦ What are the differences between L2 and L3 networks?

♦ What is a tunnel? What is a virtual network? Why are they relevant?♦ What is a tunnel? What is a virtual network? Why are they relevant?

♦ What are the differences between IPv4 and IPv6?


Switching: Circuits, Virtual Circuits, Datagram


Circuit Switching

♦ Technologies: ISDN: Basic Rate Access, E1 Ł time slots for 64 kbit/s channels

♦ Path defined during call establishment, based on the called number

♦ Switching

» Exchange of time slots

» In time and in space

» Inputs required to be synchronised


Virtual Circuit Switching

♦ Technologies: ATM, MPLS

♦ Path

» defined during the virtual circuit establishment

» Defined as a set of nodes, ports, labels

♦ Switching

» Cells, packets

» Exchange of labels» Exchange of labels

Tabela de translação de

portas / canais virtuais

1

M

a

t

1

N

2

t

Entrada

M

abc

yzc

1N2

21N

kh

m

nng

Saída

1

Porta CV Porta CV

comutação

espacial

comutação

de etiqueta

b c c

y c z y

controlo de

comutação

g h

n

k kn

m

g

cabeçalho

dados

a, b, c, ... indicador de canal virtual

b a


Packet Switching

♦ Technologies: Ethernet, IP

♦ Path defined by packet destination address


To Think About

♦ Suppose terminal a moves from port 2 to port 1

» What needs to be done so that terminal a can continue receiving packets?


L2 Networking – Frame Formats

Ethernet

7x 10101010 10101011

Protocolo=IP

PPPBit stuffing – 5 1s seguidos ŁŁŁŁ emissor introduz 0


L2 Networking - Bridge

♦ Interconnects

» 2 LAN technologies

» 2 segments of the same technology

♦ Bridge builds forwarding tables automatically Ł Address learning

Source Address of received frame is associated to a bridge input portŁ station reachable trough that portŁ station reachable trough that port

♦ Frame forwarding

» When a frame is received, its Destination Address is analysed– If address is associated to a port à frame forwarded to that port

– If not à frame transmitted through all the ports but the input port


L2 Networking - Single Tree Required

• Ethernet frame

– No hop-count

– Could loop forever in a L2 mis-configured network

– Same for broadcast packet

• Layer 2 network

– Tree topology

– Single path between every pair of stations

• Spanning Tree (ST) Protocol

– Running in bridges

– Helps building the spanning tree

– Blocks ports


Ethernet Switch

The computer attached to a port gets the illusion to have

» its own LAN segment

» its LAN segment bridged to all the other segments


Virtual LANs

♦ One bridge/switch simulates multiple LANs / broadcast domains

♦ One LAN may be extended to other bridges

w xw

y

VLAN 100

VLAN 200

B1

x

z

VLAN 100

VLAN 200

B2

[da=broadcast; sa=x; data]

[da=broadcast; sa=x; vlanid=100; data]

[da=broadcast; sa=x; data]


L3 Networking – Packet Formats

Version HLen TOS Length

Ident Flags Offset

TTL Protocol Checksum

SourceAddr

0 4 8 16 19 31

Version Traffic Class Flow Label

Payload Lengtht Next Header Hop Limit

SourceAddr (4 words)

0 4 8 16 24 31

SourceAddr

DestinationAddr

Options (variable)Pad

(variable)

Data

DestinationAddr (4 words)

Options (variable number)

Data

IPv4 IPv6


L3 Networking – Router

3ª generation router


L3 Networking – Multiple Trees …

♦ Every router

» finds the shortest path to the other routers and their attached networks

» Calculates its Shortest Path Tree (SPT)

♦ Routing protocol

» Runs in routers» Runs in routers

» Helps routers build their SPT

» RIP, OSPF, BGP

Destination Cost NextHop

A 1 A

C 1 C

D 2 C

E 2 A

F 2 A

G 3 A

B’s routing view

D

G

A

F

E

B

C


TCP

♦ Point to connection between a client and a server; port-to-port

♦ Reliable, flow control Sender

Data (SequenceNum)

Acknowledgment +AdvertisedWindow

Receiver

♦ Congestion control

AdvertisedWindow


Multimedia Traffic - Taxonomy

Applications

Elastic Real time (variation of the packet end-to-end delay)

Intolerant Tolerant

Nonadaptive Adaptive

Delay adaptiveRate adaptive

(packet loss)

(application reaction to packet loss)

(type of reaction)


RTP+RTCP/UDP

♦ Multimedia traffic

♦ Application-Level Framing

♦ Data Packets (RTP)

» sequence number

» timestamp (app defines “tick”)» timestamp (app defines “tick”)

» transported as UDP packets

♦ Control Packets (RTCP)

» sent periodically

» report loss rate (fraction of packets received since last report)

» report measured jitter


Traditional TCP/IP Communications Stack

IETF IP address

based

switching

T1

IP

TCP

APP

T1 | T2 T2 | T3

IP

T3 | T4

IP

T5

IP

TCP

APP

host bridge router router host

T4 | T5

bridge

IEEE MAC address

based

switching


Tunnel IP-in-IP

T1

IP

TCP

APP

T1 | T2 T2 | T3

IP

T3 | T4 T5

IP

TCP

APP

H1 bridge R1 R2 Server

T4 | T5

bridge

IP IP

IP

outer IP header inner IP header data

DA= 2nd IP address of R2SA= 2nd IP address of H1

TTLIP identification

IP-in-IP IP checksumflags fragment offset

lengthTOSver. IHL

DA= ServerSA=H1

TTLIP identification

lay. 4 prot. IP checksumflags fragment offset

lengthTOSver. IHL

TCP/UDP/ ... payload


Tunnel PPP over IP (E.g PPTP)

T1

IP

TCP

APP

T1 | T2 T2 | T3

IP

T3 | T4 T5

IP

TCP

APP

H1 bridge R1 R2 Server

T4 | T5

bridge

IP IP

IP

PPP

GREGRE

PPP

» GRE – virtual point-to-point link

– encapsulates a variety of

network layer protocols

– routers at remote points

– over an IP network

» PPP adequate for – Authentication

– Transporting IP packets


PPP over Ethernet

- In an ADSL router/modem the protocols of Host PC and ADSL modem are combined in a single network element


IPv6IPv6


The Need of a New IP

♦ IPv4– Small addressing space (32 bits)

– Non-continuous usage

– Some solutions used to overcome these problems

private networks (NAT), classless networks (CDIR)

♦ IETF developed new IP version: IPv6– Same principles of IPv4

– Many improvements

– Header re-defined

♦ IPv6 may be relevant for mobile communications


IPv6 – Improvements

» 128 bit addresses (16 octets, 8 shorts ). No classes

» Better QoS support (flow label)

» Native security functions (peer authentication, data encryption)

» Autoconfiguration (Plug-n-play)

» Routing

» Multicast


♦ 8 x 16 bit, hexadecimal. Separated by :

47CD : 1234 : 3200 : 0000 : 0000 : 4325 : B792 : 0428

♦ Compressed format: FF01:0:0:0:0:0:0:43 àààà FF01::43

Address Representation

♦ Compatibility with IPv4: 0:0:0:0:0:0:13.1.68.3 or ::13.1.68.3

♦ Loopback address: ::1

♦ Network prefix described by / , same as IPv4

» FEDC:BA98:7600::/40 àààà network prefix = 40 bits


Reserved Addresses

Allocation Prefix Fraction of(binary) Address Space

----------------------------------- -------- -------- -----Unassigned 0000 0000 1/256Unassigned 0000 0001 1/256Reserved for NSAP Allocation 0000 001 1/128Unassigned 0000 01 1/64Unassigned 0000 1 1/32Unassigned 0001 1/16Unassigned 0001 1/16Global Unicast 001 1/8 Unassigned 010 1/8Unassigned 011 1/8Unassigned 100 1/8Unassigned 101 1/8Unassigned 110 1/8Unassigned 1110 1/16Unassigned 1111 0 1/32Unassigned 1111 10 1/64Unassigned 1111 110 1/128Unassigned 1111 1110 0 1/512Link-Local Unicast Addresses 1111 1110 10 1/1024Site-Local Unicast Addresses 1111 1110 11 1/1024Multicast Addresses 1111 1111 1/256


Adresses –

Link-Local, Site-Local, Global Unicast, Anycast

» Link-Local

– Used for communication between hosts in the same LAN /link

– Address built from MAC address

– Routers do not foward packets having Link-Local destination addresses

» Site-Local

– Not used anymore– Not used anymore

» Global Unicast

– Global addresses

– Address: network prefix + computer identifier

– Structured prefixes

Network aggregation; less entries in the router forwarding tables

» Anycast

– Group address; packet is received by any (only one) member of the group

» Multicast

– Group address; packet received by all the members of the group


Headers IPv4 and IPv6

Version HLen TOS Length

Ident Flags Offset

TTL Protocol Checksum

SourceAddr

0 4 8 16 19 31




0 4 8 16 24 31

SourceAddr

DestinationAddr

Options (variable)Pad

(variable)

Data



Data

IPv4 IPv6


IPv6 Header

♦ Flow label à identifies packet flow

» QoS, resource reservation

» Packets receive same service

♦ Payload length




0 4 8 16 24 31

♦ Payload length

» Header not included

♦ Hop limit = TTL (v4)

♦ Next header

» Identifies next header/extension

♦ Options à included as extension headers



Data


Extension Headers

IPv6 HeaderNext Header = TCP

TCP header + data

Routing HeaderNext Header = TCP

TCP header + dataIPv6 HeaderNext Header = Routing

IPv6 HeaderNext Header = Routing

Routing HeaderNext Header = Fragment

Fragment HeaderNext Header = TCP

Fragment of

TCP header + data

IPv6 Hop-by-hop TCPDestination Routing Fragment Authenticate. ESP


Extension Headers

» Hop-by-hop

additional information, inspected by every node traversed by the packet

Other header are inspected only at the destination or at pre-defined nodes

» Destination: Information for the destination node» Destination: Information for the destination node

» Routing: List of nodes to be visited by the packet

» Fragmentation: Made by the source; it shall find MPU

» Authentication: Authentication (signature) of packet header

» ESP: Data encryption


Routing Header -

Pacote sent from S to D, through I1, I2, I3As the packet travels from S to I1:

Source Address = S Hdr Ext Len = 6Destination Address = I1 Segments Left = 3

Address[1] = I2Address[2] = I3Address[3] = D

As the packet travels from I1 to I2:

Source Address = S Hdr Ext Len = 6Destination Address = I2 Segments Left = 2Destination Address = I2 Segments Left = 2


As the packet travels from I2 to I3:

Source Address = S Hdr Ext Len = 6Destination Address = I3 Segments Left = 1


As the packet travels from I3 to D:

Source Address = S Hdr Ext Len = 6Destination Address = D Segments Left = 0

Address[1] = I1Address[2] = I2Address[3] = I3

List of visited

nodes


Configuration examples in Linux

tux13:~# /sbin/ifconfig eth0 inet6 add 2000:0:0:1:: 1/64tux13:~# ifconfig eth0eth0 Link encap:Ethernet HWaddr 00:C0:DF:08:D 5:99

inet addr:172.16.1.13 Bcast:172.16.1.255 Mask:255 .255.255.0inet6 addr: 2000:0:0:1::1/64 Scope:Globalinet6 addr: fe80::2c0:dfff:fe08:d599/10 Scope:LinkUP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1RX packets:81403 errors:0 dropped:0 overruns:0 fram e:0TX packets:2429 errors:0 dropped:0 overruns:0 carri er:0TX packets:2429 errors:0 dropped:0 overruns:0 carri er:0collisions:0 txqueuelen:100RX bytes:4981344 (4.7 MiB) TX bytes:260692 (254.5 KiB)Interrupt:5

tux13:~# /sbin/route -A inet6 add 2000::/3 gw 2000 :0:0:1::aatux13:~# route -A inet6Kernel IPv6 routing tableDestination NextHop Flags M etric Ref Use Iface::1/128 :: U 0 0 0 lo2000:0:0:1::1/128 :: U 0 0 0 lo2000:0:0:1::/64 :: UA 2 56 0 0 eth02000::/3 2000:0:0:1::aa UG 1 0 0 eth0 fe80::2c0:dfff:fe08:d599/128 :: U 0 0 0 lofe80::/10 :: UA 2 56 0 0 eth0ff00::/8 :: UA 2 56 0 0 eth0::/0 :: UDA 2 56 0 0 eth0


Identifier IEEE EUI-64

Method to create a IEEE EUI-64 identifier from an I EEE 48bit MAC identifier. This is to insert two octets, with hexadecimal valu es of 0xFF and 0xFE, in the middle of the 48 bit MAC (between the compan y_id and vendor supplied id). For example, the 48 bit IEEE MAC with global scope:

|0 1|1 3|3 4 ||0 5|6 1|2 7 |+----------------+----------------+---------------- + |cccccc0gcccccccc|ccccccccmmmmmmmm|mmmmmmmmmmmmmmmm||cccccc0gcccccccc|ccccccccmmmmmmmm|mmmmmmmmmmmmmmmm|+----------------+----------------+---------------- + 00:C0:DF:08:D5:99

where "c" are the bits of the assigned company_id, "0" is the value of the universal/local bit to indicate global scope, "g" i s individual/group bit, and "m" are the bits of the manufacturer-selected e xtension identifier. The interface identifier would be of the form:

|0 1|1 3|3 4 |4 6||0 5|6 1|2 7 |8 3|+----------------+----------------+---------------- +----------------+|cccccc1gcccccccc|cccccccc11111111|11111110mmmmmmmm |mmmmmmmmmmmmmmmm|+----------------+----------------+---------------- +----------------+

fe80::2c0:dfff:fe08:d599


Protocolo Neighbor Discovery (ND)

♦ IPv6 node uses ND for

» Find other nodes in the same link /LAN

» Find a node MAC address

ND substitutes ARP

» Find router(s) in its network

» Mantaining information about neighbour nodes

♦ ND similar to the IPv4 functions

» ARP IPv4

» ICMP Router Discovery

» ICMP Redirect


ND Messages

» ICMP messages (over IP); using Link Local addresses

» Neighbor Solicitation

Sent by a host to obtain MAC address of a neighbour / to verify its presence

» Neighbor Advertisement: Answer to the request» Neighbor Advertisement: Answer to the request

» Router Advertisement

Information about the network prefix; periodic or under request

Sent by router to IP address Link Local multicast

» Router Solicitation: host solicits from router a Router Advertisment message

» Redirect: Used by a router to inform na host about the best route to a destination


IPv6 Address Configuration


Packet Transmission


Mobility ManagementMobility Management






» Transmission


» Networking


» Research issues


» …


♦ What are the key management concepts?

♦ What functionality is associated to Mobility Management?


Handoff

♦ Transference of a call, or session, to a new cell / service-area

♦ Caused by radio link degradation (ç terminal movement)

or to re-distribute traffic

T

switch

AP

TAP

1

2

1

2

Terminal

Mobility


Other Terms Used

♦ (Terminal) Mobility types

» Macro-mobility: between organizations

» Micro-mobility: in the same organization

♦ Handover types♦ Handover types

» Vertical handover: between different technologies

» Horizontal handover: same technology, same organization


Macro Mobilility (e.g. Mobile IP)

Internet

Home

Corresponding

host

Same route

Organization 1 Organization 2

Mobile

node

Mobile

node


Micro-Mobility (e.g. Mobile IP)

Internet

Home

Corresponding

host

Same route

Organization 1 Organization 2

Mobile

node

Mobile

node


Mobility Management

♦ Mobility management

» Enables network to be aware of terminal location

» Maintains the route/connection to the terminal when it moves

♦ Mobility management Ł 2 functions– Location management

– Handoff management


Location Management

♦ Location registration/update♦ Location registration/update

» Terminal informs network about its current access point; regularly

» Network updates terminal location

♦ New Call/Session/Data delivery

» When a new Call/Session/Data arrives to terminal’s home network

network requested to find the terminal location,

by querying location databases (or by paging the terminal)

location

database


Handoff Management

♦ Maintains terminal connection/routes when terminal moves

♦ Initiation: need for handoff identified

♦ New connection/route generation

» Resources found for the handoff connection– In Network-Controlled Handoff (NCHO) à the network finds the resources

– In Mobile-Controlled Handoff (MCHO) à terminal finds resources, network approves

» Routing operations performed

♦ Data-flow control: delivery of data from old to new paths, maintaining QoS


To Think About

1. How can I manage mobility at IP layer?


Mobility Management

• Handled at multiple layers

– Data Link: 3GPP, IEEE networks

– Network: Mobile IP, HIP

– Transport: Mobile TCP Network

Transport

Application

Qu

ali

ty o

f S

ervi

ce

– Application: SIP

• Security and QoS

– Affect Mobility Management

• How to avoid new authentication at every new AP?

• How to guarantee that radio resources are available at the new AP?

Physical

Data link

Mo

bil

ity

Sec

uri

ty

Mu

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ast

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f S

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To Think About

♦ How does Skype manage computer mobility?


Research IssuesResearch Issues






» Transmission


» Networking


» Research issues


» …


Classes of Research Topics

• Basic connectivity

Network

Applications

Qu

ali

ty o

f S

ervi

ce

• Management planes

– Mobility

– Security

– Multicast

– Quality of Service

Network

Wireless Link

Mo

bil

ity

Sec

uri

ty

Mu

ltic

ast

Qu

ali

ty o

f S

ervi

ce


Research Topics – Basic Connectivity

Wireless link

» Cognitive radio

» Intelligent modulation/code

» Multi-radio resource management

Network

Wireless Link

Applications

Mo

bil

ity

Sec

uri

ty

Mu

ltic

ast

Qu

ali

ty o

f S

ervi

ce

» Multi-radio resource management

» Optimal radio usage based on neighbours information

» Software defined radio

» Multi-hop mac protocols

» MAC for multi-channel protocols

» Combination of access techniques (increase used of SDMA)


Research Topics – Basic Connectivity

Networking

» Auto-configuration

» Multi-homing

» Mesh networks

» Congestion avoidance

Network

Wireless Link

Applications

Mo

bil

ity

Sec

uri

ty

Mu

ltic

ast

Qu

ali

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f S

ervi

ce

» Congestion avoidance

» Bio-inspired routing paradigms

» Un-planned wireless networks

» Networks growing organically

» Very large networks

» Adequate support of demanding applications: peer-to-peer and mà n

» Networks driven by applications (sensor like networks)

» Networks more aware of radio conditions (cognitive like networks)

Wireless Link

Mo

bil

ity

Sec

uri

ty

Mu

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ast

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f S

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ce


Research Topics – Management Planes

♦ Moving networks

♦ Multi-layer mobility management

♦ Fast authentication techniques

♦ Multilayer security techniques

Network

Wireless Link

Applications

Mo

bil

ity

Sec

uri

ty

Mu

ltic

ast

Qu

ali

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f S

ervi

ce

♦ Multi-layer multicast management

♦ Mà N communications, P2P over wireless networks

♦ Mobility and security

♦ Mobility and QoS

♦ Secure multicast

♦ Multicast with QoS

Wireless Link

Mo

bil

ity

Sec

uri

ty

Mu

ltic

ast

Qu

ali

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f S

ervi

ce


Papers to Review

♦ Ajay Chandra, V. Gummalla, and John O. Limb, “Wireless

Medium Access Control Protocols”, IEEE Communications

Surveys , Second Quarter 2000

♦ Fotis Foukalas, Vangelis Gazis, and Nancy Alonistioti, “Cross-

Layer Design Proposals for Wireless Mobile Networks: a Survey Layer Design Proposals for Wireless Mobile Networks: a Survey

and Taxonomy”, IEEE Communications Surveys & Tutorials, 1st

Quarter 2008

♦ Provide a 2-page summary

» of one of the above papers

» in 2 weeks,

» by email to [email protected]

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