Wireless Ip2

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NOKIA wireless_ip98.ppt / 07.11.1998 / MOv page: 1

Wireless IP Marko Ovaska

1998

Introduction to the Wireless IP

Basic concepts

MOWGLI

WAP



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Levels of analysis in this presentation

Principles, Requirements•wireless environment

Protocols•MOWGLI, WAP protocols

Specifications, RFCs, draft specs•Wireless LAN: IEEE 802.11, (MobileIP), WAP, Mowgli

Products•Wireless local network

Markets•wireless LANs



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Wireless IP

• Wireless environment• networks

• mobility

• Internet protocol in wireless environment

• Non-tcp/ip solutions

• Mowgli• WAP



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Wireless Networking

• Wireless networking is the basic obstacle to be solved for the mobilecomputing

• Wireless media has different characteristics than the current wirednetworks

• Data networking protocols are optimized for the current wired networks

• The protocols are not efficient in the wireless environments

• Wireless network can be categorized to:

• Wireless LAN’s

• IEEE 802.11

• Wireless WAN’s

• GSM, GPRS, CDPD, CDMA, PHS, DoCoMo, Ricochet

• Microcell

• Bluetooth


http://slidepdf.com/reader/full/wireless-ip2 5/34©


Wireless Network• The wireless network properties differ from the wireline one

• latency

• 802.11: round-trip 2 msnormal tcp buffer size: 8KB, some W-WAN’s latency*bandwidth exceeds

this

• GSM: 0.7 s with one byte packet

extra kilo adds round trip time 0.6 seconds per kilo

• tcp throughput is related to latency: high latency, low throughput

• interactive applications suffer from long latency times

• jitter

• error rate

• non-transparency data connection in GSM offers less than 10-8 bit error rate

however this results in highly variable transmission delays

• example: 10Mbs LAN has an average of below 10 -9 bit error rate

• throughput: wireless networks could be characterized "thin”

• unexpected disconnections

• will the underlying protocol support recovery?




Mobility

• The mobile wireless networking architecture

• a wireless mobile device (mobile node)• a wireless link

• a base station (access point)

• a wireline link and landline internet

• Wireless mobile device

• a laptop, cellular phone, personal communicator

• different communication needs: office workstation vs cellular phone vs pager

• transmission: packet data vs circuit switched

• level of mobility

• travels from home network to foreign network

• full mobility, roaming from network to network

• Wireless link can consist of several hops• Base station is an intermediating agent

• connects the mobile device to wirelined world, acts as a proxy




Wireless components

Mobile node

Internet

(HER, MGBR)




Typical IP network architecture

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ACCESS ROUTER

ACCESS SERVER

PSTN/ISDN, (PR)ADSL

GSM

SWITCH/ROUTER

(BOR,MRR)

EDGE ROUTER

(MRR, HER, MGBR)

Mobile nodeInternet

(HER, MGBR)




Internet Protocol

• Internet protocols are optimized for megabit per second wireline connections

• Wireless networking solutions• unrelated to IP

• WAP, Mowgli, SNOOP

• solutions on the top of the IP

• MobileIP, optimized IP and TCP, modified TCP

• researched:

• LEO and GEO satellite links

• IP packets checksum might not be strong enough

• PPP has 16-bit CRC

• IP is end-to-end protocol

• designed to operate in a rather homogenous network




IP cont.

• Purely IP based wireless internet

• Link layer enchangements:• forward error correction

• retransmissions

• improved error detection

• MobileIP solves the addressing and routing problem

• Path MTU discovery helps to set more optimized end-to-end

• TCP might be heavy solution to tackle the wireless problem

• lightweight mobile devices: communication needs versus protocol overhead

• Compatibility is a strong need




TCP/IP cont.

• TCP optimization

• slow start termination/modification

• how will the networks congestion propagate, if slow start is abandoned?

• Increased initial sending window

• TCP header compression

• IP payload compression

• some or most of the data is already compressed

• files transferred over ftp, published pictures in web

• fast retransmit and fast recovery

• multiple ACKs notify the sender to adjust the send window and initiate fastretransmissions of the lost packet

• scheduling in TCP

• fairness: fair queuing, class-based queues

• throughput




Wireless LAN

• Wireless LAN specified in IEEE 802.11 spec

• Guarantees multi hardware vendor interoperability• Main features:

• Robust

• Data acknowledgement, RTS/CTS, data fragmentation

• Multi channel roaming. Allows multiple cells resulting in higher capasitity

• Power management

• Automatic rate selection from 1Mbps to 2Mbps

• Security WEP (wired equivalent privacy)



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Wireless LAN architecture

• Cell consists of work stations and an access point

• Access points are interconnected via distribution system (ethernet)

• The interconnected network forms an extended service set

• Portal connects different 802 based LAN’s



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• MAC similar to IEEE 802.3 (Ethernet)

• Offers common access to three physical layer interfaces• Direct Sequence Spread Spectrum

• Frequency Hopping Spread Spectrum

• Infrared

Medium access control layer

DSSSPHY

FHSSPHY

IRPHY



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• MAC features

• message fragmentation

• CSMA/CD with acknowledgement

• less impact for lost messages

• handles interference

• exponential random backoff after successfulsending, in collision and retransmission

• RTS/CTS protocol• permission to send

• DSSS physical layer features

• 2 Mbps raw data rate with a fallback to 1 Mbps

• 2.4 GHz band

• US - 11 overlapping channels

• ETS - 13 overlapping channels

• Japan - 1 channel

data

ack



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• Station joins a cell

• find a cell: beacon frame oractive probe request

• authentication

• association

• Wireless distribution system

• wireless bridges

• Automatic rate selection1Mbps / 2Mbps

• Multi channel roaming

• Roaming from cell to cell:

• not in the specification!

•Synchronization

• beacon frames

• frequency hopping

• power saving



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• Frame formats

• MAC frame

• header 30 octets

• data 0 to 2321 octets

• crc 4 octets

• ACK frame

• header 10 octets

• crc 4 octets

Frame

control

Duration

/ ID

Address

1

Address

2

Address

3

Sequence

control

Address

4

Frame

bodyCRC

Framecontrol

Duration RA CRC



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Wireless LAN, prices

Card Price $

Aironet Arlan655, ISA, 2Mbps 813Aironet Arlan690, PCMCIA, 2Mbps 654

BreezeCom PCMCIA, 2Mbps 814

Lucent Wavelan ISA, 2Mbps 545

Lucent Wavelan PCMCIA, 2Mbps 495

Access Point Price $

Aironet Arlan630, 2Mbps 1800

BreezeCOM, 3Mbps 2100Lucent WavePOINT II, 2Mbps 900

Bridges

Aironet wireless bridge, 4Mbps 3600

Aironet wireless bridge, 2Mbps 2100

BreezeCOM wireless bridge 2800 to 3300

Lucent WavePOINT II (ethernet towireless)

1300

Wireless linksBreezeLink 2Mbps, up to 50 km 5400



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MOWGLI

• Mowgli is a research project to connect a mobile office workstation to theinternet

• University of Helsinki’s CS department

• funding by Nokia, Digital, Sonera and Ministry of Education

• The mobile node is connected via a wireless link to the internet/office network

• the link is GSM non-transparent data connection

• Architecture:• Mobile node

• Wireless link

• Mobile-Connection host (MCH)

• Fixed host



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Mowgli architecture



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Mowgli

• Mowgli preserves the socket interface

• tcp/ip is replaced

• socket interface is modified: wireless environment related extensions

• Mowgli data channel service (MDCS)

• bidirectional data channel

• streamed and message channels (similar to tcp and udp)

• 256 simultaneous channels

• independent per channel flow control

• priorities

• handles disconnections

• closing if idle, reconnections

• The MDCS properties are Mowgli socket API’s QoS services



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Mowgli performance

• Measurements:

• One 100 Kb file transferred, times in seconds

From fixed host to mobile

node

From mobile node to fixed

host

Net-

work

Proto-

colMean Min Med Max Mean Min Med Max

MDCP 108,8 107,8 108,5 110,2 108,4 108,3 108,4 108,6LAN

TCP 139,2 116,6 143,1 168,2 126,3 114,4 114,7 160,5

MDCP 109,2 107,5 108,5 116,9 109,2 107,1 108,5 115,7WAN

TCP 171,9 117,6 154,6 252,7 231,2 121,4 152,6 497,1

From fixed host to mobile

node

From mobile node to fixed

host

Net-

work

Proto-

colMean Min Med Max Mean Min Med Max

MDCP 326,4 320,8 326,2 330,4 331,5 315,8 324,2 494,3LAN

TCP 513,8 413,3 495,4 591,4 344,8 299,7 325,9 490,9

MDCP 328,5 254,6 325,6 385,2 339,7 307,4 324,1 584,8WAN

TCP 362,9 251,0 364,1 480,0 388,9 253,0 358,9 759,9

• Three 100 Kb file transferred concurrently, times in seconds



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Wireless Application Protocol

• Wireless Application Protocol (WAP) is developed by WAP Forum

• WAP Forum is multivendor

• grounded by Ericsson, Motorola, Nokia and Unwired Planet

• First WAP specification 1.0 was released April 1998

• the work groups carry on to include a broader representation

• WAP is aimed to

• bring Internet content to wireless mobile device

• create a global wireless protocol specification to work across different networks

• The WAP model resembles WWW-model



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WAP Model

• The WAP model resembles WWW-model

• The WAP Gateway contains the protocol conversion services

• gateway has internet protocol specific WAP proxies



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WAP defines

• WAP defines

• micro-browser, similar to web browser

• scripting (WMLScript), similar to JavaScript

• telephony support

• formalized interfaces for different content types

• business cards, calendar events etc.

• telecommunication stack

• transport• security

• session



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WAP network



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WAP architecture

• The WAP protocol stack replaces tcp/ip in mobile devices

• The WDP unifies the different bearer properties

• WDP and the bearernetworks handle roaming

• WDP has bearer specificprofiles

• WTLS is similar to SSL

• denial-of-serviceprotection

• WSP offers two interfaces

• stream data (TCP)

• datagram (UDP)

WAP WDP



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WAP: WDP

• Two different WDP bearer specifications:

• WDP over GSM circuit switched data connection

WAP WDP t



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WAP: WDP cont.

• WDP over GPRS

WAP WTA



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WAP: WTA

• The WTA (wireless telephony application) allows telephony functionality in themobile device

• calling, incoming call, voice mail

• WTA interface contains subspecifications for different networks

• for example: GSM, PDC, IS-136

• Examples of the WTA interface:

<WML>

<FORM> <DO TYPE=“ACCEPT” TASK=”GO”

URL=”wtai:cc/mc;$(N)”/>

Enter phone number:

<INPUT TYPE=”TEXT” KEY=”N”/>

</FORM>

</WML>

WAP WTA



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WAP: WTA

<WML>

<COMMON>

<SCRIPT>

function checkNumber(N) {

if (Lang.isInt(N))

WTAI.makeCall(N);

else

Dialog.alert(“Bad phonenumber”);

}

</SCRIPT> </COMMON>

<FORM>

<DO TYPE=”ACCEPT” TASK=”GO”

URL=”wtai:cc/mc;$(N)”/>

Enter phone number:

<INPUT TYPE=”TEXT” KEY=”N”/>

</FORM>

</WML>

M k t



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Markets

• The broadband future of online services and Internet access in Europe(Datamonitor, 1997)

Households (000) 1996 1997 1998 1999 2000 2001

33,6 kb/s and below 2 625 4 715 7 239 8 050 7 100 5 200

56 kb/s + (analogue) 872 3 363 8 175 13 950 20 000ISDN 375 872 1 749 2 725 3 450 3 800

Cable modems 116 485 1 262 2 408 4 000

XDSL 87 396 1 001 1 889 3 000

Digital sat./ wireless 29 135 348 733 1 200

Other broadband 18 84 238 469 800

Total 3 000 6 709 13 451 21 799 29 999 38 000

Markets



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Markets

• Worldwide LAN switch market split by technology, 1995-2001 (Datamonitor,07/97)

USD millions 1995 1996 1997 1998 1999 2000 2001

ATM 140 340 650 1 020 1 340 1 700 2 000

10Mbps

Ethernet

1 080 2 480 3 430 4 150 4 370 4 400 4 450

100Mbps

Ethernet

80 240 610 1 350 2 700 3 900 5 100

Gigabit

Ethernet

0 0 50 200 450 950 1 700

Token ring 100 260 450 600 600 550 450

IP / L3

switching

0 0 60 200 420 800 1 150

Other 100 200 330 400 450 400 350

Total 1 500 3 520 5 580 7 920 10 330 12 700 15 200

Markets



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Markets

0

200

400

600

800

1000

1200

1996 2000

M i l l i o n s o f U s e r s

Internet UsersCellular Subscribers

Exchange Lines

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