Wireless Standards and Implementation

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Transcript of Wireless Standards and Implementation

SOI Asia IT workshop 2005

Wireless Network OperationMasafumi OE, PhD [email protected] NAOJ

Introduce myselfMy name is Masafumi OE. Im senior researcher in NAOJ.NAOJ: National Astronomical Observatory of Japan Astronomical Research institute is founded by the government.

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Introduce myselfWhy the astronomer does teach on this workshop?Im network professional researcher.Operate the entire of NAOJ network.

When I was belonging to NAIST, I had a employment opportunity that NAOJ is requesting a researcher of Network area to WIDE Project.

NAOJ Facility location MAP

MIzusawa

Nobeyama Norikura Okayama CHILI MItaka

OKINAWA HAWAII,US

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Subaru Telescope8.2m Primary Mirror located on the summit of Mauna Kea, a dormant volcano on the Big Island of Hawaii. The air is only 60% as thick as at sea level. =>The summit of Mauna Kea is one of the best astronomical observing sites in the world

Introduce yourselfYour name and etc.. Your ability and experience of a wireless. Your aim on this WS.

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QuizTest your knowledge about wireless technologies. TIME LIMIT is 30MIN.

Your aim

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GoalParticipants acquire new experience by absorbing my lecture.You practice to construct a wireless site. I hope to construct and operate a good wireless site.

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Outline of the workshopDAY1Introduction of 802.11 Basic usage and configuration of Cisco Aironet access point

DAY2Advanced configuration Designing of a wireless site

DAY3PracticeConstruct a wireless site on this site.

DAY1selfintroduce/milestone Introduction of 802.11 11:00 - 12:30 Introduction of 802.11 (2) Install and Initial setup Cisco-APs 13:30 - 15:00 Basic configuration (1) 15:30 - 17:00 Basic configuration (2)MAY BE RESCADULE ON OUR PROGRESS.

9:00 - 10:30

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DAY1 11:00-12:30Introduction of 802.11

Current state of wireless usageEverything connects with wireless!Notebook computer Personal Digital Assistant (PDA) Printer Wireless network printer HP PSC2710 Media player Handheld gaming system etc. Network Media player have built-in wireless device. Handheld Gaming system Buffalo PC-P3LWG Nintendo DS

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Background of this trendWhy is wireless installed in any equipment?This reason as follows. Decrease price of wireless devices by mass production.At 1997,PC-card type wireless NIC was $10000/unit. It have no interoperability with other makers wireless products.

Nowwireless PC-card based on 802.11b/g is only $30.

It is able to install wireless device to consumer gaming machines due to low priced wireless chipset.Nintendo DS is $150, PSP by Sony is $200.

Background of this trend(2)Miniaturization of wireless devices.SD card type IEEE802.11b wireless NIC By SanDISK

Wireless functions packaged to one chip IC.(Not including RF unit)

It becomes easy to develop built-in wireless devices. Various size (type) of NIC released.

ONLY 2.4cm

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Background of this trend(3)System technology for mobility by manufacturersIntel Centrino mobile technology.It is a mobile platform configured from of Pentium M, Intel 855 chipset and Intel Pro/wireless network connection.

Wireless built-in notebook PC was popularized.

Background of this trend(4)Enrich Hotspot service at public areas.ISP provides Hotspot service, that is wireless connectivity service at public areas. In Japan, many ISP provide hotspot services at airports, railway stations,STARBACKS, McDonalds, etc. Lufthansa provide in-flight internet service FlyNet by Connection by Boeing.

Hotspot service providers in Japan

->we can make full use of wireless devices at public area.

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Background of this trend(5)Wireless release us from a tangled wire world.In a house, there are a variety of network capable equipment, such as PC, printer, broadband routers, etc.

-> Wireless is able to easy layout of network devices.It is not restricted by the length of the cable.

->Wire instillation is required to take a lot of time and money to equip.

Technology overview of wirelsssAbout 802.11 specifications

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History of 802.11 standardizationIEEE 802.11 commission is working for standardization of wireless network. IEEE approved 802.11 at 97Has Infrared (IR) and 2.4GHz-band (microwave) as link carrier. has 1Mbps mode and 2Mbps mode as link speed.

802.11On 2.4Ghz-band, 802.11 has two types of spectrum spread method.FH-SS, Frequency Hopping - Spectrum Spread.Fault tolerance is high, transmission rate is slow. Bluetooth use FHSS.

DS-SS, Direct Sequence - Spectrum Spread.Fault tolerance is low, transmission rate is fast.

2.4GHz is ISM band.ISM: Industry Science Medical band can be used without the radio license.Example) Microwave cooker, Cordless phone

Regulation for ISM-band MAY be different in each country.

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FHSS on 802.11Spread-spectrum signals are highly resistant to noise and interference. b: Actual bandwidthHopping Hopping T i m e Hopping Radio frequency

DS-SSSenderAdd PN-Sequence

Receiver

spread-spectrum transmissions

De-Spread

SpreadDecode the digital data from the spectrum

Generate a spectrum from digital data

Spread the spectrum with pseudo noise

De-spread the spread spectrum with pseudo noise

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802.11b was on stage.IEEE approved 802.11b at 99 It is CCK that is extension of 802.11 DSSS.Added 5.5Mbps and 11Mbps as link speed.11b has the function of dynamically changing link speed to 1, 2, 5.5 and 11Mbps.The speed is depending on a radio signal condition.

About IEEE802.11a(1)IEEE approved 802.11a at 1999, too.Product released at 01. Manufactures released after successful of 802.11b.

802.11a use 5GHz-band5Ghz is ISM band.Regulation for ISM-band MAY be different in each country.

5GHz-band may have some effect by rain and snow. 5Ghz of straightness is higher than 2.4GHz of it.S/N rate is low on furnitures shadow.

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About IEEE802.11a(2)Link speed is 54Mbps.802.11a use OFDM (Orthogonal Frequency Division Multiplexing) as modulation. OFDM is able to use a radio bandwidth in efficiently than DSSS in 802.11b. Merit of OFDM is strong in phasing and the multi-pass.

TDMATime Division Multiple Access

TIME

Frequency

Ex) 2G Mobile phone

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FDMAFrequency Division Multiple Access

TIME

Frequency

Ex) AM Radio

Spectrum of FDMASignal Level Frequency bandwidth

Frequency

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Orthogonal-FDMSignal Level OFDMDistributes the data over a large number of carriers that are spaced apart at precise frequencies. This spacing provides the "orthogonally" in this technique

Frequency bandwidth

Frequency

About IEEE802.11a(3)Usage limitation of 802.11a is different each country.In Japan, Permitted frequency from 5.15GHz to 5.25GHz without a license and also indoor use only.Because 802.11a interferes in weather observation system, AMEDAS, that use 5GHz-band.

In US, permitted 5.155.25GHz, 5.255.35GHz and 5.7255.825GHz-band.US has three times of radio band range than Japan.

Country localized products fit each countrys law.Japan localized 11a card cant associate with US localized access point.

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About IEEE802.11a(4)Usage limitation of 802.11a is different each country.In Japan, Permitted frequency from 5.15GHz to 5.25GHz without a license and also indoor use only.Because 802.11a interferes in weather observation system, AMEDAS, that use 5GHz-band.

In US, permitted 5.155.25GHz, 5.25 5.35GHz and 5.7255.825GHz-band.US has three times of radio band range than Japan.

About IEEE802.11gFirst product was released at 03.Manufacturers release products while IEEE is finalizing specification of 802.11g from draft.

11g uses same frequency band as 11b.2.4Ghz-band.

Link speed is up to 54Mbps.11g use OFDM / PBCC(=Packet Binary Convolution Code) / OFDM-CCK as modulation.

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Compatibility with 11b(1)11b and 11g use same 2.4GHz-band with different modulation architecture.11b cant recognized 11gs OFDM frame.OFDM

11g client 11b client AP 11b cant recognize OFDM frame.

DATA Collision DATACCK

Start sending datas.

Compatibility with 11b(2)11g use OFDM-CCK modulation to avoid framing collisions between 11b and 11g. OFDM-CCK is send CTS (Clear to send) frame with CCK modulation before OFDM modulation and ACK frame after send.802.11b clients recognize CTS frame and stop to send data until receiving ACK.

The performance decreases when both of 11g client and 11b client exist in same area because OFDM-CCK has more overhead than OFDM.CCK

11g client 11b client AP

CTS

OFDM

DATACCK

Stop sending data

ACKOVERHEAD OVERHEAD

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ChannelsChannels and available frequency on 11a/b/g are different each country.Channel availability of NIC is different by selling region of product. We should pay attention for participant's country.

802.11b Channels

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Channel ID (x: permitted)

permitted on Mar 2005.

802.11g Channels

Not match channels with other countries

802.11a

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Three operation modeIEEE802.11 has three operation mode.Infrastructure mode ad-hoc mode Repeater mode

Infrastructure modeNode associate with AP as client. Client communicate via access point(AP). AP works as bridge. This mode is usually used in wireless network.

AP

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Ad-hoc modeA node commutates other node without AP. No AP is required

Repeater mode(1)Connects between LAN and LAN via AP.AP

AP

ro ad

Bldg A

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