KONSEP DASAR WiFiTELKOM Training CenterBandung 2005

Perbedaan Wired vs WLAN

Wireless LANs: KARAKTERISTIKTIPEInfrastructure basedAdhocKEUNTUNGANFlexible deploymentMinimal wiring difficultiesMore robust against disasters (earthquake etc)Historic buildings, conferences, trade shows,KERUGIANLow bandwidth compared to wired networks (1-10 Mbit/s)Proprietary solutionsNeed to follow wireless spectrum regulations

WIRED VS WLAN

Wired vs Wireless

WiredWirelessInstalasiRelative lebih sulitLebih mudahFleksibilitasTerbatasLebih fleksibelCostLebih murah Lebih mahalPerformanceSangat bagusbagusMaintenanceCukup besarLebih kecilSecurityCukup bagusCukup bagusMobilityTerbatas (tidak memungkinkan)Mendukung (jarak 100 m dari AP)

PERSAMAAN WIRED DAN WIRELESSIf both A and C sense the channel to be idle at the same time, they send at the same time.Collision can be detected at sender in Ethernet.Half-duplex radios in wireless cannot detect collision at sender.ABCABCEthernet LANWireless LAN

*Presentation_ID 2000, Cisco Systems, Inc. SPEKTRUM WiFi

ISM Unlicensed Frequency BandsExtremelyLowVeryLowLowMediumHighVeryHighUltraHighSuperHighInfraredVisibleLightUltra-violetX-RaysAudioAM BroadcastShort Wave RadioFM BroadcastTelevisionInfrared wireless LANCellular (840MHz)NPCS (1.9GHz)

Spread Spectrum Approaches

Direct Sequence Frequency Hopping

Frequency2.4 GHz2.4835 GHzTimeFrequency2.4 GHz2.4835 GHzFrequency HoppingDirect SequenceDS vs. FH: Ketahanan Terhadap InterferensiFH system hops around interferenceLost packets are re-transmitted on next hopData may be decoded from redundant bitsCan move to an alternate channel to avoid interferenceChannel 1Channel 3Channel 2

Frequency Hopping79 Channels, 1 MHz EachChanges frequency (Hops) at least every 0.4 secondsSynchronized hopping requiredFrequency2.400 GHz2.483 GHzTime123456789

ALOKASI FREKUENSI WLAN

Scalability FH VS DS

Wireless Capacity per Cell

1.6Mbps FH, 2 Mbps FH, 2 Mbps DS, 11Mbps DS

Possible Cell Capacity of Co-Located Access Points

This chart illustrates the potential data rate capacity in a cell employing multiple co-located APs. In the DSSS case, each AP provides 2 Mbps over the air data rate capacity up to 3 APs. This provides a maximum capacity of 6 Mbps per cell. Adding any more APs will not provide any more capacity. In fact, if you added more than 3 APs you would lose capacity. This is because any AP after 3 interferes with the other APs.

In the FHSS case, the analysis is much more complex. If you remember the last chart on FH, recall the illustration of each hop generating interference with the adjacent channels causing 5 channels to be interfered with. The most optimistic case would be that only 3 channels are interfered with. If this was the case, then the top line will show that if you were to stack 26 APs in a cell you could reach a capacity of 13.5 Mbps. Although the chart cuts of the data points of adding more APs, this line would progress down in capacity as more APs are added. The more practical and realistic case for a FHSS system would be recognizing that 5 channels were effected per hop. In this case you can see that when you co-locate 16 APs you will achieve a maximum cell capacity of 8 Mbps.

As you can see from this example, the DSSS system can provide more capacity up to 6 Mbps using only 3 APs. For 6 Mbps, an FHSS will require 8 APs. Using the more realistic curve, the FHSS can provide 2 Mbps more capacity per cell by adding 8 more APs. In conclusion, DSSS is a more optimum choice when you need only up to 6 Mbps per cell capacity. I am not aware of any WLAN installations that need more than this today. If they did, FHSS could be deployed, although at a higher cost.

Distribusi kanal berdasarkan ETSIChannel numberTop of channelCenter frequencyBottom of channel

Distribusi Kanal berdasarkan FCC

Kanal 802.11b Perbandingan Teknologi WLAN (14) 22 MHz wide channels (11 under FCC/ISTC) 3 non-overlapping channels (1, 6,11)

Distribusi Kanal Global

Komponen/elemen Wi-Fi

KOMPONEN WLANAccess Point (sentral WLAN)AP dapat difungsikan sebagai Bridge, Point to Point atau Point to MultiPoint. Komponen ini sebagai interface antara station satu dengan lainnya yang tersambung secara wireless. Disamping itu AP merupakan jembatan penghubung ke jaringan wired LAN yang sudah ada.Card WiFi (untuk dipasang di station)NIC wireless LAN dipasang di sisi station dapat berupa PCMCIA card, USB card atau PCI card.StationStation yang dimaksud di sini dapat berupa PC (desktop), notebook atau PDA yang telah dilengkapi dengan interface WLAN.Asesories

CONTOH PERANGKAT WLAN

CPE WIRELESS LAN

STANDARD WIFI DAN GENERIKNYA

Klasifikasi WirelessWAN WAN-MAN MANPico-Cell MAN-LAN PAN LAN-PAN 0km~50km~2km~10mPersonal Operating SpaceCourtesy of IEEE 802.15, Jan. 2001WPANBluetoothWLANIEEE802.11HyperLanWWANGSM/ GPRS / CDMAWMANIEEE802.16

W-LANAMerupakan asosiasi edukasi bersifat non profitMisi : Mengedukasi pasar mengenai Wireless LANMenyediakan informasi tentang aplikasi, issue dan trend Wireless LAN.Merupakan sumber informasi bagi customer, industry, press dan analystsAnggota : 32 perusahaan

WECADibentuk pada tahun 1999Mengintroduksi Wi-Fi (Wireless Fidelity) sebagai nama populer dari Wireless LAN IEEE 802.11bMisi : Mengetes dan memberikan sertifikasi interoperability bagi produk-produk Wi-FiMempromosikan Wi-Fi sebagai standard global Wireless LANAnggota : 157 perusahaanLaboratorium testing di USA dan UK, selanjutnya akan dibuka di Tokyo dan Singapura mengingat 45% produk Wi-Fi berasal dari Asia

ISU INTEROPERABILITYWECA mengumumkan pada pertengahan 2001 bahwa 93 jenis produk W-LAN telah melewati test sertifikasi Wi-FiContoh peroduk yang telah memperoleh sertifikasi Wi-Fi : Cisco, Cabletron, 3 Com, Fujitsu, Avaya, NEC, Nokia, Lucent, Siemens, Samsung, Flexuscom, Zixel, Xircom, Compaq, NestComm, Proxim, Symbol Technology, etcSertifikasi IEEE 802.11a / Wi-Fi5 oleh WECA dimulai pada September 2002

PENGEMBANGAN STANDARWECA mulai melakukan sertifikasi interoperability terhadap produk IEEE 802.11a / Wi-Fi5 pada September 2002Organisasi IEEE sedang mengembangkan standard baru disebut IEEE 802.11g untuk wireless LAN kecepatan tinggi berbasis OFDM yang bekerja pada frekuensi 2,4 GHz

Generik IEEE 802.11

StandardsDescriptions802.11cImproves interoperability802.11dMultiple Regulatory Domains (Improve Roaming; New country)802.11eQuality of Service (QoS); prioritizing voice or video 802.11fInter-Access Point Protocol (IAPP)802.11hSupports measuring and managing the 5-GHz radio signals in 802.11a 802.11iEnhanced Security (repairs WEP weakness)802.11jExtensions for Japan 802.11kPassing specific radio frequency health and management data to higher-level management apps.

Generik IEEE 802.11

StandardsBand (GHz)Raw Throughput802.112.42Mbps (Legacy)802.11a554Mbps802.11b2.411Mbps 802.11g2.454Mbps802.11n??100 Mbps

SEJARAH : 802.11 Legacy1997: Standard AwalNama Standard : IEEE 802.11-1997Updated: IEEE 802.11-1999 Starting Point untuk Standard-based WLAN Untuk 2 Mbps: Direct sequence Spread Spectrum (DSSS) modulationUntuk 1-2 Mbps Frequency Hopping Spread Spectrum (FHSS)Keduanya menggunakan ISM band 2.4 GHz

KARAKTERISTIK 802.11 (1)

802.11a802.11b802.11gFrekuensi5 GHz2,4 GHz2,4 GHz

Data rate54 Mbps11 Mbps54 MbpsModulasiOFDMCCKOFDM/CCKSecurityWEP (WPA)WEP (WPA)WEP (WPA),11iAvailable bandwidth300 MHz83,5 MHz83,5 MHzData Rate Per Channel6,9,12,18,24,36, 48,54 Mbps1,2,5,11 Mbps1, 2, 5.5, 6, 9, 11, 12, 18, 24, 36, 48, 54 Mbs SecurityWEP (WPA)WEP (WPA)WEP (WPA), 11iKompatibilitasTidak kompatibel bmatureKompatiel bCoverage25-50 m30-75 m30-75 m

Jumlah non overlapping channel833Harga Lebih mahal (sedikit vendor)Murah Agak mahal

KARAKTERISTIK 802.11 (2)Maximum throughput

Max Link RateTheoritical Max TCP RateThoeritical MaxUDP Rate802.11b11 Mbps5,9 Mbps7,1 Mps802.11g54 Mbps24,4 Mbps30,5 Mbps802.11a54 Mbps24,4 Mbps30,5 Mbps

KARAKTERISTIK 802.11b802.11b-1999Range 50 100 m. (depends on obstacles)Omnidirectial antennaIndoor / Outdoor / Point-to-point (high-gain external antennas)Max throughput of 11 Mbit/s (5.5, 2,1 Mbps)Attenuation: Metal, Thick walls, Water, etc.ISM Band 2.4 GHz; DSSS; CSMA/CA14 overlapping ch. (Different ch.for different countries)3 simultaneously ch. (such as 1, 6, and 11) Proprietary speed extension "802.11b+" (22, 33 and 44 Mbit/s)Kompatible dengan standard asli 802.11 DSSS.Area coverage lebih luas dapat digunakan untuk ruangan terbuka, semi terbuka atau pun bersekatBersifat cost effective dengan harga yang rendah dan coverage yang luasSudah banyak diimplementasikan sehingga memungkinkan roaming antar zona W-LANInteroperability memungkinkan implementasi dengan produk yang bervariasi (multi vendor)

KARAKTERISTIK 802.11a2001 (802.11a-1999) Max throughput of 54 Mbps (Normally around 20 Mbps)ISM Band 5 GHz (FCC may open more spectrum)Mempunyai lebih banyak non-overlapping channel (12 nonoverlapping channels)8 dedicated to indoor4 to point to point Not widely deployed (US. / Japan)802.11b popularityLess range / More attenuationLack of roll back compatibility (now support a,b,and g)In Europe considering HiperLan2Dapat digunakan komplemen jaringan 802.11bPotensi Interferensi lebih sedikit (5 GHz)Tidak kompatible dengan standar sebelumnya (802.11b)Bandwidth besar dengan area coverage terbatas, sesuai untuk ruangan dengan tingkat kepadatan user yang tinggiDapat digunakan untuk aplikasi dengan bandwidth tinggi spt video stream, ftp dllPenambahan jumlah Access Point untuk memperbesar coverage

KARAKTERISTIK 802.11g3rd quarter 2003ISM Band 2.4 GHz Max throughput of 54 Mbps (Net 24.7 Mbps)Dual-band / Tri-mode supporting a, b, and gA single wireless card / Access point Kompatibel dengan 802.11bTransfer data lebih besar dibanding 802.11b Dengan speed 802.11a dapat menjangkau coverage yang lebih luasLebih cepat dibandingkan dengan 802.11b (54Mb vs 11Mb) Support 802.11 i

KELEBIHAN & KEKURANGAN 802.11a

KelebihanSpektrum lebih besar dibanding 802.11bDapat digunakan dikomplemen jaringan 802.11bBandwidth yang lebih besar (54 Mb)Potensi Interferensi lebih sedikit (5 GHz)Mempunyai lebih banyak non-overlapping channel

KelemahanArea jangkauan sempit Tidak kompatible dengan stadard sebelumnya

KELEBIHAN & KEKURANGAN 802.11bKelebihan:ReliableJangkauan luas Mudah diintegrasikan dengan jaringan yang Menggunakan kabel.Kompatible dengan standard asli 802.11 DSSS.Kekurangan:Kecepatan lebih rendah (11 Mbps)

KELEBIHAN & KEKURANGAN 802.11gKelebihan Kompatibel dengan 802.11b Transfer data lebih besar dibanding 802.11b Jangkauan lebih besar dibanding 802.11a Lebih cepat dibandingkan dengan 802.11b (24Mb vs 11Mb)

Kekurangan Frekuensi crowded

Data rates and RangeSource: Proxim

PERBANDINGAN COVERAGE

WLAN GoalKomplemen wired LANsDua Alasan Utama :Mendukung mobilitas user & Peningkatan produktifitasFleksibilitas dalam instalasi pada situasi perkabelan yang sulit

Topologi Wireless LAN

APA ITU WIRELESS LAN Wireless LAN adalah sistem jaringan komputer dan shared network equipment lainnya yang memungkinkan untuk saling terhubung dan berkomunikasi tanpa melalui media transmisi kabel.

Apakah Wireless LAN?Berkaitan dgn:Lokal, bukan area luasDalam gedung atau area kampus utk pengguna mobileBeberapa km utk point-to-point (LAN to LAN)Radio atau infraredTidak perlu ijinPengguna memiliki perangkatnya (tidak ada biaya pemakaian)Tidak terkait dgn:Seluler teleponPagerCDMA

DEFINISIWireless LAN menggunakan gelombang radio electromagnetic untuk berkomunikasi dari suatu tempat ke tempat yang lain dalam model :Peer to Peer (Ad Hoc)Client Server Umumnya diimplementasikan sebagai jaringan Extension atau Alternative dari jaringan Wired LANFrekuensi ISM (Industrial, Scientific and Medical) frequency bands - no licensing required902-928 MHz, 2400-2483.5 MHz, 5725-5850 MHz

PERTANYAAN UMUM WLAN

TANYA JAWAB Seberapa cepat?Maximum datarateTypical throughput 11/54 MB5.5/27 MBSeberapa jauh ?OutdoorsIndoors3 km100 m Seberapa banyak?Maximum clients per APTypical clients per AP AP dalam satu lokasi 2048Sama dengan ethernet3 (b)

2 Implementasi berbeda Wireless LANWireless NetworkingKoneksitas pengguna bergerakWireless Bridging Koneksitas LAN - LAN

Local Area Network (LAN)

Topologi LAN

Topologi Repeater Wireless

Topologi Wireless LAN

Topologi Sistem RedudansiWireless ClientsLAN BackboneChannel 1Channel 6

Topologi Peer to PeerKonfigurasi Peer to Peer(Ad Hoc mode)Wireless ClientsWireless CellModem

Seting KanalContoh Site Survey kanalChannel 1Channel 6Channel 11Channel 1Channel 6Channel 11Channel 11Channel 1Channel 6Channel 11

Cakupan Access Point & Kecepatan Data

Implentasi Multi-rate Contoh Site Survey Bandwidth

Arsitektur Micro selular

Microcellular ArchitectureRoaming

WIRELESS MESHTransit Link (TL) @ 5 GHzMenggunakan 802.11aAccess Link (AL) @ 2.4 GHzMenggunakan 802.11bAPCoverage Access Link (AL) dari AP

Keuntungan & Kerugian

Kelebihan WLAN vs WiredPlug and play : dapat digunakan secara langsungMeningkatkan produktivitas and Layanan (Mobility): Akses informasi secara Real-Time Dapat mengakses darimana pun dalam area organisasi/ kantorKecepatan instalasi : dibandingkan penggelaran jaringan kabel yang membutuhkan waktu yang lamaFlexibel : Dapat digelar dimana saja bahkan di tempat dimana kabel tidak mungkin diimplementasikanReduksi biaya : Dalam kasus pengembangan, pemindahan maupun perubahan konfigurasi LAN

MENGATASI KERUMITAN INSTALASI KABEL

MENGATASI KERUMITAN INSTALASI KABEL

KERUGIAN WLAN

Low bandwidth dibanding dengan jaringan kabel Frekuensi bebas Isu keamananHarga awal lebih mahal

Terima kasih

*Wired LANs require that users locate in one place and stay thereWLANs are an extension to the wired LAN networkWLANs can be an overlay to or substitute for traditional wired LAN networks

With Cisco Wireless LANs, portable PC users can:Move freely around a facility Enjoy real time access to the wired LAN, at wired Ethernet speedsAccess ALL the resources of wired LANs

**There are three unlicensed bands - 900 MHz, 2.4 GHz, and 5.7 GHz within the Industry, Medical and Scientific FrequencyThis presentation focuses on 2.4 GHz because our products use those bands today and it adheres to the IEEE 802.11b standard. The 5.7 GHz band is promising for future products and we are actively pursuing projects in that area. Recently, the FCC also opened up the 5.2 GHz band for unlicensed use by high speed data communications devices. 5.2 GHz is the same band that is used for the ETSI HYPERLAN specification in Europe.A nearby neighbor of the 900 MHz band is the cellular phone system. This helped the early development of the WLAN industry in the 900 MHz band because of the availability of low cost small RF components in that band. 2.4GHz has a neighbor in the PCS system. That helps with component costs too.There are no such neighbors for the 5 GHz band. The WLAN industry will have to driver the development of low cost components for 5GHz on our own. We think this means practical, cost effective, PCMCIA products in the 5 GHz band are a few years away. The other downside to 5GHz is the poor range performance as compared to 2.4GHz.*

The deciding factor is price/performance.

DS generally delivers higher performance in range and throughput.

*DS muscles through the interference, whereas FH hops around the interference. A DS system can also bet set to a different channel to avoid the interference altogether.

Many cordless phones today are starting to operate in the 2.4 GHz band using FH technology. The FH phone is far more likely to experience interference from the DS system than vice versa.

*With Frequency Hopping, the FCC requires the use of 75 different channels before repeating the use of any one channel.The maximum time on any one frequency is 400mS in any 30 second period.802.11 has defined 26 hopping patterns in three different sets. These 26 patterns are designed to have minimum interference with each other. These patterns are called orthogonal patterns.If interference appears on a frequency, any data for that frequency is impaired, and will be retransmitted on the next frequency.

*DS evenly inclines to a maximum of 3 Access Points per Cell Area.Using 2 Mbps technology, a FH product will outperform a DS product operating at 2MB in a scalability test. However, with the ability to have 11Mbps products in the same cell, you can obtain 33 Mbps of datarate. FH curves up and peaks with 15 systems allowing a maximum data rate of 24 Mbps. After that point is reached, there are more collisions that occur on the RF which brings down the overall effective data rate. This is very similar to adding more stations to an already fully utilized shared Ethernet network. More collisions occur, and throughput actually goes down.**3*The MOST Common questions: How fast, how far and how many!Note that we separate the Sales term of datarate and the technical term throughput. Who really cares if the datarate is 1.6Mb but you only get 500KB throughput? There are systems out there that are NOT 802.11, with datarates at 1.6Mb but with throughput of only 500kb. That is a whopping 31% efficiency of the RF spectrum! Others claim 3Mb, but find that only works to about 30 ft. At the maximum rated distance they get a total of perhaps 300Kbps throughput!The questions to ask is: What is the throughput of the system at the MAXIMUM rated distance? With Cisco, ALL of our ratings are AT the maximum distance, unless specifically stated for a lower rate!How Many? That is a question that can only be answered by the customer and the integrator together. While the Cisco AP will allow 2048 associations with EACH AP in the system, the limiting factor is the applications. If the system is used for minimal usage (e-mail, net cruising etc.) then perhaps 50 users per AP can work fine. For high data applications, the 340 acts like a wired 10MB Ethernet segment! ******In*******