Chapter 2 Wireless Modes Technologies

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Chapter 2Wireless Modes Technologies

• Dr Lami Kaya

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WLAN Modes and Topologies

• Wireless networks can be configured to operate in
  two major modes
• Ad-hoc
• Infrastructure
• In most cases WLANS are configured to operate in
  infrastructure mode

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WLAN Modlari veTopolojileri

• Kablosuz aglar iki ana modda çalismak için
  yapilandirilabilir
• Ad-hoc
• Infrastructure
• Pek çok durumda WLAN lar infrastructure mod unda
  çalistirilir

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Wireless Network Structure
Basic Service Set BSS
Independent BSS
Infrastructure BSS
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Kablosuz Ag Yapisi
Basic Service Set BSS
Independent (bagimsiz) BSS
Infrastructure BSS
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Ad-hoc (roaming) Mode

• Allow devices to communicate directly with each
  other
• Devices can move about within the network and can
  connect with whatever wireless devices that are
  within its range
• no base stations
• nodes can only transmit to other nodes within
  coverage
• nodes organize themselves into a network

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Ad-hoc (gezici) Mode

• Cihazlarin direk olarak birbirleriyle iletisimine
  imkan saglar
• Cihazlar ag içerisinde hareket edebilir ve kendi
  kapsama alaninda olan herhangi bir araca
  baglanabilir
• Baz istasyonu yoktur
• Node (dügüm) ler sadece kapsama alanindaki diger
  nodelar ile haberlesir
• Nodelar ag içinde kendi kendilerine organize
  olurlar

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Mobile Ad-hoc Network (MANET)

• A MANET, sometimes called a mobile mesh network,
  is a self-configuring network of mobile devices
  connected by wireless links
• Each device in a MANET is free to move
  independently in any direction
• Each must forward traffic unrelated to its own
  use,
• and therefore be a router
• The primary challenge in building a MANET is
  equipping each device to continuously maintain
  the information required to properly route
  traffic.

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Mobile Ad-hoc Network (MANET)

• Bir MANET, bazen mobil mesh network olarak ifade
  edilir, kablosuz baglanti araciligiyla baglanti
  saglanmis bir kendinden-konfigüre edilen
  tasinabilir araçtir.
• MANET deki her araç, herhangi bir yöne örgürce
  hareket etmekte serbesttir.
• Her biri kendi kullanimina alakasiz olan trafigi
  de iletmek zorundadir,
• Yani router gibi olur
• The primary challenge in building a MANET is
  equipping each device to continuously maintain
  the information required to properly route
  traffic.

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Mobile Ad-hoc Network (MANET)

• Nodes in mobile ad-hoc network are free to move
  and organize themselves in an arbitrary fashion.
• Each user is free to roam about while
  communication with others.
• The path between each pair of the users may have
  multiple links and the radio between them can be
  heterogeneous
• This allows an association of various links to be
  a part of the same network.
• Mobile ad-hoc networks can turn the dream of
  getting connected "anywhere and at any time" into
  reality

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Mobile Ad-hoc Network (MANET)

• Mobil ad-hoc aglarda nod lar hareket etmede ve
  kendilerini organize etmede serbesttir.
• Her kullanici, digerleriyle iletisim kurarken
  gezinmede özgürdür.
• Her kullanici ikilisinin arasindaki yol çok
  yönlüdür ve aralarindaki ortam heterojendir
• Bu çesitli baglantilarin birlesimi, ayni bir agin
  parçalari olmasina imkan saglar.
• Mobile ad-hoc networks herhangi bir yerde
  herhangi bir zamanda baglanti kurulabilmesi
  demektir.

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Wireless Ad-hoc Protocols

• In ad-hoc networks, nodes do not start out
  familiar with the topology of their networks
• instead, they have to discover it
• The basic idea is that a new node may announce
  its presence and should listen for announcements
  broadcast by its neighbours
• Each node learns about nodes nearby and how to
  reach them, and may announce that it, too, can
  reach them

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Wireless Ad-hoc Protocols

• In ad-hoc network lerde node lar kendi
  aglarindaki topoloji bilgisi ile çalismaya
  baglamazlar
• Bunun yerine topolojiyi kesif ederler
• Ana mantik su sekildedir yeni bir nod kendi
  varligini digerlerine bildirmeli ve kendi
  komsularinin bildirimlerini dinlemelidir
• Her nod yakinindaki nodlari ve onlara nasil
  ulasilacagini ögrenir ve digerlerine bildirir.

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Wireless Ad-hoc Protocols

• Wireless ad-hoc routing protocols can be
  classified into two major categories
• Pro-active (table-driven) routing
• Reactive (on-demand) routing
• Some examples of ad-hoc protocols
• Ad-hoc on-demand distance vector (AODV)
• Destination sequenced distance vector (DSDV)
• Dynamic MANET on-demand (DYMO)
• Dynamic source routing (DSR)
• Optimized link state routing protocol (OLSR)

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Wireless Ad-hoc Protocols

• Wireless ad-hoc routing protocol leri iki ana
  kategoride siniflandirilabilir
• Pro-active (table-driven) routing
• Reactive (on-demand) routing
• Bazi ad-hoc protocol leri
• Ad-hoc on-demand distance vector (AODV)
• Destination sequenced distance vector (DSDV)
• Dynamic MANET on-demand (DYMO)
• Dynamic source routing (DSR)
• Optimized link state routing protocol (OLSR)

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Infrastructure Mode Wireless Networks

• In an infrastructure WLAN, the wireless stations
  usually remain in a relatively fixed location or
  area

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Infrastructure Modunda Kablosuz Aglar

• infrastructure WLAN da, kablosuz istasyonlar
  genellikle sabit yer ve alan da kalirlar

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Basic Service Set (BSS)

• Single cell
• With Access Point (AP) ? BSS
• Without AP ( ad-hoc) ? IBSS
• BSS terminals AP A set of signaling rules

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Basic Service Set (BSS)

• Tek hücre
• Access Point ile (AP) ? BSS
• AP olmadan ( ad-hoc) ? IBSS
• BSS terminaller AP sinyal kurallari kümesi

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WLAN Roaming

• In multi-cell WLAN networks that comprise a
  number of AP, users or stations can roam freely
  once they have been authenticated and associated
  to the wireless network.
• This means station can pass in/out of range of
  the various WLAN cells, searching and associating
  with the strongest RF signal as they move across
  the multi-cell network
• WLAN roaming has two general types
• Seamless roaming
• More commonly associated with cellular phones
• Nomadic roaming
• Used with WLAN devices

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WLAN Roaming(yer degistirme)

• Serbest olarak hareket eden birden fazla AP,
  kullanici ve istasyondan olusan multi-cell WLAN
  aglar da, kimlik dogrulama yapilmasi ve kablosuz
  ag ile baglanti saglanmasi gerekir.
• Istasyonlar multi-cell networkler arasinda
  hareket ederken istasyon birden fazla WLAN
  alaninin içine girip çikabilir, arayabilir ve en
  güçlü RF sinyali ile birlestirilebilir.
• WLAN roaming iki genel tiptedir
• Seamless(kesintisiz) roaming
• Genel olarak cep telefonlari ile alakalidir
• Nomadic(göçebe) roaming
• WLAN araçlari ile kullanilir

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802.11 Roaming

• Roaming on an 802.11 uses a break before make
  sequence
• Breaks a roaming devices existing AP link before
  establishing with a new AP
• From an 802.11 perspective, WLAN roaming consists
  of four distinct steps
• Disassociation
• Search
• Re-association
• Authentication
• Consider the affect of break before make on
• TCP transmission
• UDP transmission

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802.11 Roaming

• 802.11 de yerdegistirme break before make dizi
  kullanir
• Yeni bir AP ile baglanti yapilamadan önce,
  yerdegistiren aracin mevcut AP baglantisi
  kesilir.
• 802.11 de, WLAN roaming 4 ayri basamaktan olusur
• Disassociation (baglantiyi koparma)
• Search (arama)
• Re-association (tekrar baglantiya geçme)
• Authentication (kimlik dogrulama)
• break before make isleminin
• TCP transmission
• UDP transmission
• ürezine etkileri

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Extended Service Set (ESS)
Backbone Structure
AP
AP

• Multiple APs form what is known as ESS
• AP s periodically transmit beacons
• Wireless terminals scan and discover
• Authentication and association
• Adjacent AP s use different radio channels

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Extended Service Set (ESS)
Omurga yapisi
AP
AP

• Birden fazla AP den olusan format ESS olarak
  bilinir
• AP ler periyodik olarak beacon lari iletir
• Wireless terminalleri tarar ve anlamaya çalisir
• Kimlik dogrulama ve baglanti
• Komsu AP ler farkli radyo kanallari kullanir

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WLAN Roaming Configuration

• WLAN devices are able to roam within an ESS (the
  same domain) without the need for changing their
  IP configuration
• Because WLAN roaming occurs at layer 2
• If a WLAN device roam across several domains, its
  IP configuration must be updated
• This means any upper-layer activity, such as
  application-driven sessions must be dropped

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WLAN Roaming Konfigürasyonu

• WLAN araçlari kendi IP konfigürasyonunu
  degistirmeden, bir ESS de yerdegistirme
  yetenegine sahiptir.
• Çünkü WLAN roaming Katman 2 de olur
• Eger bir WLAN araci farkli domainlerde hareket
  ederse, IP konfigürasyonu update edilmek
  zorundadir
• This means any upper-layer activity, such as
  application-driven sessions must be dropped

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Personal Area Network (PAN)

• A PAN is a computer network used for
  communication among computer devices (cell phones
  and PDAs) built around a personal operating space
  (POS)
• This is commonly defined to range 1-10 m
• A PAN can be constructed around a person, while
  he/she standing still or in motion
• The advantage of a PAN is its capability to
  automatically detect and link to any device that
  falls within the POS in a seamless and
  transparent way.

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Personal Area Network (PAN)

• PAN bir personal operating space (POS) de
  kurulmus bilgisayar araçlari arasinda(cep tel ve
  PDA)ki iletisim için kullanilan bir bilgisayar
  agidir.
• 1-10 m alaninda genellikle tanimlidir
• PAN bir hareket eden veya sabit duran kisi
  etrafinda insa edilebilir.
• PAN in avantaji, otomatik tanima(detect) yetenegi
  ve bir POS a düsen herhangi bir araca seamless ve
  transparent yolla baglanti saglar.

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Personal Area Network (PAN)

• Wireless PANs typically use cable replacement
  technologies, such as
• Bluetooth
• Infrared Data Association (IrDA)
• ZigBee,
• Radio Frequency Identification (RFID)
• A PAN can be also be constructed using wireline
  bus structures, such as
• USB
• IEEE 1394 (FireWire)

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Personal Area Network (PAN)

• Wireless PANs tipik olarak kablo yerine
  kullanilan teknolijiler kullanir
• Bluetooth
• Infrared Data Association (IrDA)
• ZigBee,
• Radio Frequency Identification (RFID)
• PAN kablo yollu yapilar kullanilarak
  olusturulabilir
• USB
• IEEE 1394 (FireWire)

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Hot Spots

• A hotspot is a physical location that offers
  internet access over a wireless LAN through the
  use of a shared internet connection and a single
  router
• Hotspots are often found at restaurants, train
  stations, fuel stations airports, libraries,
  hotels, hospitals, coffee shops, stores,
  supermarkets and other public places.
• Many universities, schools, military bases ,
  parks and campgrounds have wireless networks in
  large area.
• The public can use a laptop, WiFi phone, or other
  suitable portable device to access the wireless
  connection

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Hot Spots

• hotspot paylasilan bir internet baglantisini ve
  tek bir router i kullanan bir kablosuz LAN
  üzerinden internete erisim saglayan fiziksel bir
  konumdur.
• Hotspots genelde restaurant lar tren
  istanyonlari, benzin istasyonlari, kütüphane,
  havaalani, otal, hastane, kafe, süpermarket ve
  diger halka açik alanlarda bulunabilir.
• Pek çok üniversite, okul, askeri üsler, parklar
  ve kamp alanlari genis alanda kablosuz aglara
  sahiptir.
• Halk laptop, WiFi telefon ve diger uygun
  araçlarla kablosuz erisim saglayabilir

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Wireless Network Media

• Network media are the physical communication
  links used to connect nodes on a network
• Every network uses at least one form of network
  medium
• Copper
• Fiber-optic
• Air (RF signals, satellite)

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Wireless Network Ortami

• Ag ortami, bir ag daki nod lari baglamakta
  kullanilan fiziksel iletisim baglaridir
• Her ag, en az bir sekilde ag ortami kullanir
• Copper (bakir kablo)
• Fiber-optic
• Air (RF signals, satellite) (hava)

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Radio Frequency (RF)

• Radio frequency (RF) radiation is a subset of
  electromagnetic radiation with
• a wavelength range of 100km to 1mm,
• a frequency range of 300 Hz to 3000 GHz
• This range of electromagnetic radiation
  constitutes the radio spectrum and corresponds to
  the frequency of alternating current electrical
  signals used to produce and detect radio waves.
• RF can refer to electromagnetic oscillations
• either electrical circuits or radiation through
  air and space
• Like other subsets of electromagnetic radiation,
  RF travels at the speed of light.

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Radyo Frekansi(RF)

• Radio frequency (RF) yayilimi
• 100km ile 1mm arasinda dalga boyu(wavelength),
• 300 Hz to 3000 GHz arasinda frekans
• ile elektromanyetik yayilimin bir alt kümesidir
• Bu araliklardaki elektro manyetik yayilim radio
  spectrum u olusturu ve radyo dalgalarini üretme
  ve tespit etmekte kullanilan frekans degismini
  ifade eder.
• RF eketromanyetik salinimlar olarak ifade edilir
• Hava ve uzayda yayilim veya elektrik devresi
• Diger elektromanyetik yayilimlar gibi, RF isik
  hizinda hareket eder.

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RF Spectrum